Pocket book of steelwww.corusautomotive.com

Corus AutomotiveIARC BuildingUniversity of WarwickCoventryCV4 7AL

t: +44 (0) 2476 241 200

Corus Automotive

Your complete reference guide to steel in the automotive industry

Care has been taken to ensure that this information is accurate, but Corus Group plc, and its subsidiaries, does not accept responsibility or liability for errors or information which is found to be misleading.

Copyright 2007Corus UK Limited

Foreword

by Philippe Varin, Chief Executive of CorusI am delighted to welcome you to this ‘Pocket book of steel’ and hope that you will find it packed with useful information on the role and importance of steel in the automotive industry.

Since Corus was formed in 1999, we have been providing customers and others across the industry with knowledge and information about our products, services and technologies. This pocket book is the latest step in presenting steel’s credentials to a challenging market sector. It describes the issues that drive Corus to develop purpose-designed automotive steels for lightweight, durable, high-quality and cost-effective automotive body structures, power-train components, chassis frames and many other vehicle applications. It also provides background on how steel is processed for its wide range of applications and the steel technologies that are essential for modern car making.

Our hope in producing this book is that it will not just inform, but provide a basis for deeper and more sustainable dialogue and understanding between us. With around 16 per cent of our total turnover coming from the automotive sector – more than €2bn – we are committed to our automotive customers, who trust us to deliver ‘Value in steel’.

Contents

Corus in automotive

Steel: the basicsSteel in carsThe multi-materials carSteelmakingChemical compositionsCharacteristicsSteel typesFrom steelworks to assembly line

Automotive industry issuesDrivers for changeThe history of the carSafetyEnvironmentWeight and cost reductionQuality and service

Corus in action: Case studies

Steel R&D technologies

Looking to the future

About Corus

Glossary

5

4-7

8-2310-1112-1314-15161718-1920-23

24-4124-2526-2728-3132-3536-3940-41

42-47

48-53

54-57

58-59

60-63

Corus in automotiveWorking in partnership – making a difference

With 16 per cent of our business in the automotive sector, Corus is committed to this industry. Corus combines its materials knowledge, automotive engineering expertise and manufacturing-process innovation to offer its customers unique solutions. We help customers to produce cost-effective, lighter weight, higher quality vehicles.

Corus works in partnership with customers, offering advanced technology and hands-on help at pre-development, design engineering and production stages. This helps facilitate improvements in the design, manufacture and durability of cars, enhancing their appearance, performance and end-of-life recyclability.

We understand the industry challengesBe it changes in emissions, safety performance legislation, the contemporary needs of car designers, or pushing the boundaries of material performance, we share knowledge and respond to the challenges of our automotive customers. Our aim is to help customers get the best value from every gram of steel they buy from us.

By listening to customers, attending key European automotive forums and through focused market analysis, our specialists keep abreast of industry trends and look for opportunities to bring a new competitiveness or performance edge to automotive manufacturing through the specification and application of steel.

We listen, and we respondSometimes, specific adjustments to material specifications are needed to enhance the manufacturability and performance of specialised components. Corus supports new and ongoing vehicle and product development programmes, working with customers to develop tailored specifications for their needs, and giving advice on the selection of steel fit for task.

When Xtrac approached Corus asking for gear steels with better impact resistance, machinability and carburising qualities, Corus offered to adjust the standard chemistry of its Hy-Tuf product, improving its chemical tolerances and cleanness. The resulting XMO materials enabled Xtrac to make narrower gears that can run at higher temperatures, requiring smaller oil-coolers and thereby improving the aerodynamics of the vehicle.

Corus in Automotive: Working in partnership

6 7

When Ford was looking for ways to improve the crash performance and lightness of its latest Galaxy model, Corus was ready with its High Strength Steels and the advanced automotive engineering services needed to implement them in body structures.

Just as the automotive industry was moving to eliminate hexavalent chromium commonly used in the production of adhesive coated metals, Corus was ready with Envirobond™ – an alternative adhesive coating process for metal trim parts.

When Mitsubishi wanted help to improve press-shop performance on its five-door Colt model, Corus was ready with a unique portable measurement and analysis system, PHAST™ and In-Form™, which helped NedCar to improve capability in its bodyside stamping process.

When Corus was asked for steels with better machinability by Wigpool – a supplier of machined parts to motorcycle manufacturer Triumph – Corus worked with the company to select Hitenspeed 65, a material that delivered machinability improvements to a factor of three, but with no loss of strength performance.

Find out more: www.corusautomotive.com

Making a difference

“Our customers get value from every gram of steel they buy from us”

Corus in Automotive: Making a difference

8 9

We innovateOur customers don’t just buy our metal, they buy the thinking and innovation that have gone into the development, distribution and technology needed to deploy that metal for its most effective use – ‘intelligent metal’.

One example of this is the Corus-Vegter materials model, for which data is made freely available on the internet for engineers studying how to form complex 3D parts from 2D blanks. This advanced data model bridges the gap in knowledge between how traditional steels stretch as they are pressed in a press shop, and how the particular properties of Advanced High Strength Steels modify this behaviour.

Years of research and development have resulted in a model that is used directly inside the industry standard PAM-STAMP™ forming analysis software package. It is an innovation that improves the accuracy of simulated virtual prototypes. Improved confidence

in this process permits engineers to develop parts by computer simulation long before hardware prototypes are made, benefiting original equipment manufacturers (OEMs) and their Tier suppliers. The model is easy to download from the Corus automotive website.

We make a differenceCorus realises that building long-term relationships with customers is key to our success. Our customers know that by involving Corus early in their new product development cycles, substantial savings can be made when their product eventually goes into production.

We deliverTo make cars efficiently it is vital that supplies of parts and materials are delivered to OEMs and their Tier suppliers on time. Consistent quality, integrated supply chains and timely supply are all critical factors that need to be satisfied.

To meet these needs, Corus has its own distribution network, including numerous pre-production capabilities at service centres around the world for de-coiling and blanking sheet steel.

When BMW wanted to use extra-thick sheet steel bodysides for its new Mini Cabriolet (compensating for the lack of roof), Corus was ready with a large-bed press blanking line, capable of pressing out blanks up to the required 3mm thickness. The Wednesfield Automotive Service Centre that supplied these blanks boasts a comprehensive line-up of dedicated automotive processing facilities. A range of automotive customers, including Land Rover, benefit from the full-bodyside-capable 400 and 600-tonne blanking

lines, and a Tailor Welded Blank facility to create blanks for door and body-structure parts.

With all Corus service centres accredited to TS16949 quality standards, automotive component makers are enjoying the benefits of significant Corus investment. Corus distribution and service centres are sited throughout Europe. More recently, Corus Distribution has been responding to the gradual eastward migration of automotive manufacturing, setting up a service centre near Gyor in Hungary at the end of 2006.

Find out more: www.corusautomotive.comFind out more: www.corusautomotive.com/vegter

Did you know?In the UK alone, Corus makes over 21,000 strip steel deliveries a year to automotive customers, most of it via the rail network.

Steel – the basicsSteel - the basics

10 11

Steel is a very special material. With the addition of tiny amounts of other elements, iron can be transformed into a versatile engineering metal capable of withstanding extreme gearbox pressures or the immense forces in a car crash.

Page 10-11

Page 12-13

Page 14-15

Page 16

Page 17

Page 18-19

Page 20-23

Did you know?Steel is the most widely recycled engineering material in the world. It can be recycled over and over again without loss of properties.

In this sectionThe following pages illustrate some of the basic facts about carbon steel and how its versatility enables it to be used throughout automotive manufacturing and endlessly recycled into new products.

Steel in carsIllustrating the versatility of steel and the types of components and applications it is used for in cars.

The multi-materials carComparing steel’s physical properties with those of other materials used in the manufacture of a passenger car.

SteelmakingDescribing how steel is made using one of two main production methods, outlining the benefits of each.

Chemical compositionsExplaining how the chemical composition of steel affects its strength and other properties.

CharacteristicsDescribing how the different characteristics of steel are used to best advantage in automotive manufacturing.

Steel typesExplaining the differences between types of steel and what they mean for automotive manufacturing.

From steelworks to car plantOutlining the processes that transform steel into myriad automotive components.

Steel in cars

Thick section strip and tube for structural reinforcements and seat structures

Engineering services to prove out materials selection and engineering solutions.

Deep drawing quality for surface appearance

Electroplated strip for brake and fuel lines, and electrical parts

Gear steels tuned for machinability and hardenability

Steel tubes for hydroformed subframes and other chassis parts

Ultra-clean steels for precision parts, eg. diesel injectors

Alloy steel rod for high-temperature applications, eg. engine valves

Services to make and weld blanks for vehicle structural parts.

R&D services to assist selection of materials for formability and weldability.

High-grade wire rod drawn into tyre cord

Ultra High Strength Steels for ‘B’ pillars

Advanced High Strength Steels for lighter vehicle structures

Billets for suspension and engine part forgings

Aluminium-coated strip for exhausts

Steel accounts for more than 50 per cent of the weight of an average passenger car. The major applications are shown here.

High Strength Steels for crash performance

Deep drawing quality steels for complex shapes

Bake-hardenable steel for door skins and bonnets

Spring steels for suspension components

Electrical steels for starter motors and alternators

Steel - the basics: Steel in cars

12 13

Find out more: www.corusautomotive.com/en/products

Steel for chassis bolts and rivets

The multi-materials car

A car is built from many different materials, although the main structure – known as the Body In White (BIW) – is usually made of steel pressings welded together to form a strong and stiff frame. This method of construction accounts for 99.9 per cent of all the cars produced in the world. The remaining 0.1 per cent are mostly constructed with an aluminium BIW, while a very small number (less than 0.01 per cent) are constructed from carbon-fibre composite (see Fig. 2 opposite).

Table 1: Alternative materials - potential weight saving vs cost

steel aluminium magnesium % weight reduction % cost increase (kg) (kg) (kg) (part) (vehicle) (part)

Bonnet 14.8 8.3 N/A 44 0.48 300 (assembly)

Body in 285 218 N/A 23.5 3.90 250 white(BIW)

Door 15.7 9.5 N/A 39 0.40 275(assembly)

IP Beam 11.4 N/A 6.3 45 0.33 350(instrumentpanel support)

examplevehicle mass

of 1700kg

examplevehicle mass

of 1350kg

examplevehicle mass

of 1550kg

examplevehicle mass

of 1550kg

Carbon fibre

Aluminium

Steel

Source: SMMT 2001 report

Annual production (x 1000 units)

Vehi

cle

pric

e E

uro

(x10

00)

Fig. 2 Vehicle production vs vehicle price vs market share

Steel - the basics: The multi-materials car

14 15

steel 56% iron 12%

plastics 11%

Fig. 1

aluminium 6% rubber 4%glass 3%

others 8%

The material properties of steel (with its wide range of yield strength combined with high modulus) together with ease of manufacture and low cost, mean that steel-intensive vehicles have by far the largest share of the market. The high cost of alternative materials such as aluminium or composites mean that steel’s position as the first-choice material is secure.

The BIW of a vehicle accounts for 20 per cent of the vehicle mass. The weight of the closures (doors, bonnet and boot/rear hatch), chassis (suspension parts) and driveline bring the total amount of steel and other ferrous metals to more than 60 per cent (see Fig. 1).

In recent years, the amount of ferrous metal has declined, mostly driven by manufacturers replacing iron with aluminium for engine castings. The percentage of sheet steel per car has also dropped, mainly due to:• Higher levels of equipment, trim and soundproofing.• More aluminium used in wheels and suspension parts.• More moulded plastics, especially under the bonnet.

The environmental and economic requirements for reduced fuel consumption have also led to an increase in the use of lightweight materials for components that bolt on to a conventional steel vehicle, but at a cost: see Table 1 opposite.

Did you know?The human body contains 4.2g of iron, enough to make a piece of car door 27mm x 27mm.

A brief guide to the materials that make up the cars of today.

Fig. 1

8%

6%4% 3%

11%

12%

56%

<0.01%

<0.1%

>99.9%

Source of Fig. 2 and Table 1: Corus

Steelmaking

Here we explain the principal commercial methods for making steel: Basic Oxygen Steelmaking (BOS) and the Electric Arc Furnace (EAF).

Steel - the basics: Steelmaking

16 17

Since BOS relies on a supply of liquid iron from a blast furnace, we must first describe iron making. Iron ore (iron oxides), coke and limestone are fed into a blast furnace where they are heated to around 15000 C. At this temperature carbon monoxide is formed by the reactions of coke and limestone with furnace gases. The lime now acts as a fluxing agent, removing impurities in the form of a slag which floats on

top of the iron. Carbon monoxide reacts with iron ore to give molton iron, which collects at the bottom of the furnace. The resulting carbon-rich ‘pig iron’ is then poured off and transported to the BOS plant.

Basic Oxygen SteelmakingIn the BOS process, steel is made by blowing oxygen into liquid iron using a water-cooled lance. Oxygen reacts with excess carbon and other impurities, which are released as gases. This exothermic reaction takes place under alkaline conditions (i.e. ‘basic’), with the rise in temperature controlled to some extent by the addition of scrap steel.

A steelworks that makes steel by this route and shares a site with a blast furnace for the provision of liquid iron is known as an ‘integrated’ steelworks.

The BOS process is used where large volumes of similar steel types are required. It is the most common route for making formable strip steels for car bodyshells and ultra-clean steels with low residuals for products such as tyre cord and valve springs.

These steels have low levels of trace elements, which make them ideal for forming into body panels and other thin-section, deep-drawn parts.

Electric Arc Furnace steelmakingThe Electric Arc Furnace (EAF) process is simpler and more flexible. The process uses electric current to produce a high-temperature arc inside a furnace containing scrap steel. One furnace can be used to produce smaller batches of a wider variety of steel types than the BOS process.

While the feedstock for the BOS process is molten pig iron, for the EAF process it is almost 100 per cent steel scrap – resulting in steel being the most recycled engineering material in the world.

The EAF process is preferred for making specialist steels such as heat-treatable forging billets, high-temperature alloys and stainless steels.

Secondary steelmakingThe steel from either BOS or EAF then goes through a series of operations while still liquid, which can include vacuum degassing, argon stirring and the addition of other metallic alloying elements by powder injection. Fine tuning of the steel chemistry in this way allows the steelmaker to produce thousands of grades of steel from the same basic composition. The steel is then poured by a continuous-casting process to form a range of thickness known as slabs, blooms or billets.

Further processingBillets may be supplied directly to forgers for hot forging components such as crankshafts, camshafts and connecting rods, or hot rolled into sections for reinforcement brackets and door hinges.

However, most steel for automotive use is supplied in the form of sheet, ranging in thickness from 0.5mm to 4mm, in widths up to two metres. This sheet is produced by hot rolling a slab, with the resultant oxide surface being removed by ‘pickling’ in an acid bath. For optimum mechanical properties and control of surface finish, most automotive sheet steel is cold rolled. A corrosion-preventing metallic coating, usually zinc based, is then applied by electro or hot-dip galvanizing. Cold-rolled sheet requires heat treatment (annealing) that is often carried out within the coating process, before a final cold roll (temper rolling).

Sheet steel is rolled into coils weighing up to 20 tonnes for shipment by road or rail.

Find out more: www.corusgroup.com/en/responsibility

Blast furnace

Electric arc furnace

Chemical compositionsAlloying elements are added to steel to create the desired strength and formability properties for specific automotive components.

Steel for automotive purposes is made up of iron (generally more than 99 per cent) and a range of other alloying elements, the most important of which is carbon.

Under a microscope, at x1000 magnification it can be seen that steel is actually made up of tiny crystals known as grains. These grains of steel are formed when liquid steel cools to a solid, the atoms of iron within each grain, aligning in a precise crystalline array. The size, shape and composition of these grains has a major effect on the strength and formability of the steel.

A carbon atom is smaller than an iron atom, and provides a strengthening mechanism by sitting between the iron atoms, preventing the rows of atoms sliding over one another. At carbon levels below 0.001 per cent, the steel is known as interstitial free (IF) and therefore has a low yield strength.

Other alloying elements, such as phosphorous or vanadium, have larger atoms that strengthen by substitution for an iron atom. This is known as solid-solution strengthening. Steel manufacturers combine this with other techniques to produce steel with an optimum balance of properties.

Characteristics

Steel offers an impressive range of properties to meet the demands of every automotive application.

Iron atoms Interstitial atoms (carbon, nitrogen)

Substitutional atom (eg. phosphorous, vanadium)

Steel grade DP600 through microscope at x1000 magnification

Steel - the basics: Chemical compositions Steel - the basics: Characteristics

18 19

Find out more: www.corusgroup.com/en/responsibility

Steel for use in automotive applications ranges from the most formable grades with a low yield strength of 140 N/mm² to ultra-high-strength tyre-cord steel with a strength of 2,500 N/mm².

Some grades have specialised processing for a specific end use, such as super-clean steels for use in fuel injection systems and forging grades for crankshafts, camshafts and connecting rods. Grades specific to connecting rods, for example, can be deliberately fracture split as part of the manufacturing process.

A key requirement for sheet steel intended for use in automotive pressings is that it is formable, so that it can be stretched without undue thinning in a press to form complex shapes. Softer grades of steel, having low yield strength, tend to be highly formable but lack the strength needed for the main load-bearing members of a vehicle.Higher-strength steel parts may be more difficult to form, since they do not stretch so readily, but offer potential for weight reduction.

Above: Automotive crankshaft hot forged from a steel billet. Component shown is from an in-line six-cylinder engine.

Below: A tailgate inner pressing

Source of diagrams above and below: Corus

Fig. 4 below illustrates the properties of three different grades of sheet steel, and identifies where in a vehicle structure they are most likely to be found.

Ultra High Strength Steels, for safety-critical parts, especially

for maintaining a passenger survival space in crash events

High Strength Steels with a good balance of

strength, formability, energy absorption and durability

Steels with excellent formability, eg. for deep drawing

As well as solid-solution strengthening, steel manufacturers can use a range of techniques to make higher-performance steels. These techniques include grain refinement, work hardening, precipitation hardening and heat treatment.

Using these techniques, sheet steels can be developed with the ideal combination of formability and strength for specific automotive applications.

For example, Fig. 3 below demonstrates the range of formability (elongation) and yield strength for a wide range of automotive sheet steel types.

(Yield strength is defined as the point at which the steel begins to permanently stretch or deform.)

Steel types

Table 2: Steel types

Type Description

IF

BH

HSLA

CMn

DP

Boron

TRIP

MART

TWIP

Interstitial Free

Bake Hardening

High Strength - Low Alloy

Carbon Manganese

Dual Phase

Boron steel

Transformation Induced

Plasticity

Martensitic

Twinning Induced Plasticity

Strength range

Ultra High StrengthSteel

High StrengthSteel

Formable steel

Each ellipse below represents the grades available within each steel type or ‘family’. The name for each family – see Table 2 – reflects the method by which the steel achieves its formability or strength.

Steel - the basics: Steel types

20 21

600

Elongation %

Str

ess

N/m

m2

10 20 30 40 50 Elongation %

Yie

ld s

tren

gth

N/m

m2

Steel grades fall into a number of general types, each suitable for different categories of component in a car.

The highest strength steel shown here has a yield strength (at point X) of 800N/mm² – roughly equal to eight tonnes per square centimetre.

(X)

Fig. 3 Types of sheet steel

Fig. 4 Application of types of sheet steel

Source of diagrams Fig. 3 and Fig. 4: Corus

From steelworks to assembly line

Did you know?The highest strength steel in everyday use is the cold-drawn wire used for piano wire and tyre cord – a 12mm diameter cable made from this wire is strong enough to lift a 30-tonne truck.

Steel - the basics: From steelworks to assembly line

22 23

A range of secondary processes is used to give a steel component its final properties and shape.

Heat treatmentHeat treatment alters the mechanical properties of metal, improving ductility or strength or a combination of both.

Annealing at around 6000 C is used to remove the work hardening that results from cold rolling – creating a softer, more formable steel.

Quenching (rapid cooling) of steel from a temperature of around 7500 C results in the formation of (very hard) martensite.

Bake-hardening (BH) steels gain additional strength as the pressed components (such as outer panels and closures) go through the paint oven after painting.

CoatingsCoil-applied coatings (i.e. applied at the steelworks) for automotive use are generally metallic and based on zinc, aluminium, copper and tin. Zinc coatings are used to enhance corrosion resistance, while other

BlankingSteel strip leaves the steelworks in the form of coils. The process of de-coiling and cutting the strip into shapes ready for pressing into three-dimensional components is known as blanking.

Blanks of different thicknesses, grades or coatings can be welded together. These Tailor Welded Blanks (TWBs) are typically used for parts that need additional strength and stiffness in applications such as door inners, reinforcing the areas where hinges and locks are attached.

metal coatings can enhance wear resistance and electrical conductivity or promote adhesion.

It is now possible for a vehicle manufacturer to offer 30-year anti-perforation warranties due to the combined performance of coil-applied metallic coatings and paint-shop applied organic coatings.

Forming Press forming converts flat sheet steel into the three-dimensional shapes used to generate complex parts and box sections in a car’s body in white (BIW). Sheet steel blanks are inserted into a press, the outer edge of the sheet is clamped and the sheet stamped between a male and a female die. To obtain a deep section requires extra metal, which is pulled from the clamped region; the part is then described as ‘drawn’. Very deep shapes, such as door inners or spare-wheel wells, are ‘deep drawn’ and require the most formable grades of steel. The higher-strength steel used in modern cars requires presses with higher press forces.

Press Hardening, also known as die-quenching, is similar to press forming, but in the press-hardening process the steel is first heated to 9500 C and simultaneously pressed and quenched in the die to produce a very strong martensitic steel.

Roll forming is a process where sheet metal is progressively folded to shape through a series of rollers.

Did you know?A 283mm x 230mm bloom measuring four metres long can be rolled into a coil of rod measuring up to 11 km long (for 5.5mm diameter rod) and weighing 2.2 tonnes.

24 25

From steelworks to assembly line

Steel - the basics: From steelworks to assembly line

The resulting profiles are used for seat rails and chassis rails for trucks.

Hydroforming can be used to form tube or sheet steel. In tube hydroforming, a tube is filled with fluid and pressurised. The tube then expands to match the shape of an external die. Chassis frames, subframes and instrument panel support beams are examples of hydroformable parts.

ForgingEngine parts such as camshafts, crankshafts and piston connecting rods are examples of parts made by forging. In the forging process, a steel billet is first heated in a furnace. The red-hot billet is then transferred to a press where it is progressively stamped into shape between two dies. The steel forging produced is close to the final part shape and therefore requires little machining. The flow of material in the forging process results in a preferred grain structure, enhancing both toughness and fatigue performance.

JoiningCommonly used joining techniques in automotive assembly include spot welding, laser welding, hybrid welding, arc welding, adhesive bonding, mechanical joining and brazing. Efficient and reliable joining is a critical technology in the assembly of automotive structures, and the quality of joins can greatly affect the durability of the finished product. Joining of dissimilar metals (eg. steel to aluminium) is an emerging technology, as carmakers tune weight distribution to enhance a vehicle’s handling or stability.

MachiningAs well as forgings, steel in the form of rod, bar and tube is machined to produce a wide range of powertrain and suspension components, such as gear shafts, stub axles and constant-velocity joints. Typical machining operations are cutting, milling, boring and grinding. Grinding provides the high surface finish required for the longevity of plain bearings and oil seals.

Free-cutting engineering steels are designed to enable the rapid removal of metal during machining, and to prolong tool life.

Surface treatmentWear resistance of bearing surfaces or cylinder bores can be increased by a number of chemical, thermal and mechanical methods. One popular method is nitriding – where a heated component is immersed in nitrogen-rich fluid. The atoms of nitrogen that diffuse into the surface of the steel increase surface hardness without causing embrittlement.

A mechanical method, such as shot peening (hammering with metal beads), leaves residual compressive stresses in the surface of the component, which considerably improves fatigue performance.

Find out more: www.corusautomotive.com/hydroforming Find out more: www.corusautomotive.com/publications

Fracture splittingConnecting rod ‘big ends’ are bolted together to produce a strong and stiff circular housing for the big end bearing shells. These big ends can be made by fracture splitting using a grade of steel that, under the right conditions, breaks cleanly to provide precision-matching surfaces. This method reduces the number of further machining operations and is a good example of material choice enabling lean manufacturing.

2011 2012 2013 2014 2015

27

2006 2007 2008 2009 2010

26

Drivers for change

Automotive industry issues: Drivers for change

Automotive industry issues

Steelmakers need to work closely with carmakers to develop advanced materials that respond to the issues that drive the automotive industry.

In this sectionThis section explains how materials suppliers like Corus are changing to help carmakers through the development of new products – helping them to meet the challenges they face in the areas of:• Safety• Environment• Weight and cost reduction• Quality and service

Legislative changesThe diagram below shows the timetable for some of the anticipated global legislation that is driving change in the industry. This legislation covers:• Occupant safety – making cars safer for their passengers.• Pedestrian safety – increasing the chances of survival for pedestrians hit by cars. • Emissions – meeting legislative targets. • End of Life Vehicle Directive (ELVD) – reducing landfill by recovery and reuse of vehicle mass (85 per cent by 2006, 95 per cent by 2015).

The main drivers of change in the global automotive industry are:

• Marketing & brand management - for product differentiation and image• Cost reduction - improving development & production processes and introducing new technology.• Legislation - the need to meet rising safety, emissions and environmental challenges• Feature content - to satisfy increasing consumer expectations

For steelmakers, satisfying the demands created by these drivers means developing new materials and more efficient processes. It also means building a good working knowledge of the industries that their materials are supplied into. The natural consequence is that steelmakers must maintain constant

dialogue with carmakers, and work collaboratively with them.

Carmakers are acutely aware that good and early selection of materials is essential to the integrity of a vehicle’s structure and the effectiveness of manufacturing processes. The combination of these demands and the constant pressure to bring cars to market faster, means that steelmakers like Corus are taking an increasingly active role in recommending the optimum steels for particular engineering applications.

All participants in the vehicle design process now accept that the cost of developing new platforms is mostly committed before designs are fixed and any tooling metal is cut. This increases the reliance on ever more accurate computer simulation methods.

2011

Pub

licat

ion

of E

urop

ean

cras

h

com

pat

ibili

ty le

gisl

atio

n?

2012

New

veh

icle

tar

get

120g

/km

CO

2

(n

ew c

ycle

)

2013

Com

put

er s

imul

atio

n to

sup

ple

men

t te

stin

g fo

r le

gisl

ativ

e

ass

essm

ent?

2013

Leg

isla

tion

chan

ges

due

to

har

mon

isat

ion?

2015

95%

per

veh

icle

mas

s re

used

/

rec

over

ed, 8

5% p

er v

ehic

le m

ass

reu

sed

/rec

ycle

d

2006

Car

man

ufac

ture

rs w

ill a

chie

ve

w

aste

rec

over

y ta

rget

of 8

5%

2006

Gra

nula

ted

tyr

es b

anne

d fr

om

la

ndfil

l20

07 C

ost

free

tak

e-b

ack,

all

vehi

cles

01/

2007

85%

reu

se/r

ecyc

le20

07 U

pgr

ade

FMV

SS

208

incr

ease

d

im

pac

t sp

eed

(mid

-siz

ed d

umm

y)

2008

New

veh

icle

tar

get

140g

/km

CO

2

(n

ew c

ycle

) 20

08 F

MV

SS

202

rear

imp

act

head

r

estr

aint

2009

Rev

ised

FM

VS

S21

4 (s

ide

imp

act)

-

new

dum

mie

s, p

ole

test

2010

Ped

estr

ian

Pro

tect

ion

Dire

ctiv

e

200

3/10

2/E

C: P

hase

II20

10 U

pgr

ade

to F

MV

SS

216

incr

ease

d

r

oof c

rush

load

2010

“E

uro

5” e

mis

sion

s: d

iese

l

par

ticul

ates

80%

red

uctio

n, p

etro

l

NO

x &

HC

25%

red

uctio

n20

10 N

CA

P t

o b

egin

tes

ting

activ

e

saf

ety

syst

ems

for

colli

sion

avo

idan

ce

Dates and targets below are subject to continual revision.

Ford model

T

Renault Laguna

BMW 5/6 series

Green issues

Safety/product liability issues

Increased use of higher strength steels &improvements in design optimisation techniques

Lotus Elise

1960 1970 1980 1990 2000 2010

1965

Com

pul

sory

fitt

ing

of fr

ont

seat

bel

ts (E

U)

1968

Com

pul

sory

fitt

ing

of fr

ont

seat

bel

ts (U

S)

1973

Sta

tic s

ide

crus

h te

st (U

S)

1974

Firs

t ai

r b

ags

fitte

d

1975

Firs

t fu

lly g

alva

nise

d s

teel

bod

y19

78 S

tart

of U

S N

CA

P19

78 F

irst

fully

rob

otis

ed b

ody

asse

mb

ly 19

80s

Sta

rt o

f use

of F

inite

Ele

men

t

Ana

lysi

s &

Com

put

er A

ided

Des

ign

1996

Firs

t b

ond

ed s

truc

ture

1997

Sta

rt o

f Eur

opea

n N

ew C

ar A

sses

smen

t

Pro

gram

me.

Pub

lic a

war

enes

s of

saf

ety

issu

es20

01 F

irst

car

to a

chie

ve 5

sta

r N

CA

P20

03 F

irst

alum

iniu

m/s

teel

hyb

rid b

ody

29

Dodge

LanciaLambda

CitroenTraction Avant

Volkswagen Beetle

PanhardDyna Z

Advancements in steelquality & pressing

techniques

Start of transportation for the masses

Oilshortages

Fiat 500Topolino

Mini

Citroen 2 CV

Morris Minor

Porsche 911

Fiat Ritmo/Strada

1910 1920 1930 1940 1950 1960

1910

Sta

rt o

f mas

s p

rod

uctio

n

1914

Firs

t m

ass-

pro

duc

ed a

ll-st

eel b

ody

1920

Hyd

raul

ic b

raki

ng w

as in

trod

uced

.

1923

Firs

t m

onoc

oque

bod

y st

ruct

ure

1933

Firs

t m

ass-

pro

duc

ed m

onoc

oque

1940

Firs

t fo

ur w

heel

driv

e m

ulti-

pur

pos

e

vehi

cle

1954

Firs

t m

ass-

pro

duc

ed a

lum

iniu

m

m

onoc

oque

1958

Firs

t E

urop

ean

cras

h re

gula

tion

Automotive industry issues: History of the car

28

This timeline demonstrates how changes in legislation, technology and the market in the automotive industry have driven material development and application.

The history of the carSteel became the material of choice as soon as mass production and moving production lines dramatically lowered the cost of vehicle manufacture in the early

20th century. The challenge for steelmakers has been to keep pace with the ever increasing rate of technological change in this dynamic industry.

Austin 7

Jaguar E-Type

VW Golf

Range Rover

Willys Jeep

Chevrolet Corvair

Renault Espace

Citroen DS

Toyota Prius

31

Safety in side impact is a key automotive design requirement, covered by extensive legislation and consumer testing in each of the major world markets.

steel, and there is little scope for reducing the number of parts.

Lower-strength steel structures can also be used but are more difficult to engineer to achieve the desired performance. Thicker gauges and more parts are required, leading to heavier vehicles with less internal packaging space.

The ideal material for side-impact protection would be a low-cost, high-strength grade that can be formed, joined and coated easily. Corus continues to develop their products towards this goal. In the meantime, vehicle designers are using their expertise to find solutions that still give the desired performance.

Safety for side impact

The basic principles of side-impact design require the control of vehicle intrusion, intrusion profile and intrusion rate. This is typically achieved using a strong B-pillar structure which pivots around the connection with the roof and deflects more at the base, while avoiding collapse in the middle.

Manufacturers employ a number of strategies for achieving the desired performance, ranging from using High Strength Steels and fewer parts to using lower strength grades but with more parts and thicker gauges. A good illustration is the extent to which press-hardened boron steel is used in B-pillar structures.

Boron steel parts offer very high strength and are hot-formed, which enables complex shapes to be made, facilitating a reduction in the number of parts required. The disadvantages are high forming costs, slow process times and more complex joining and coating.

High Strength Steel parts offer an alternative to boron steel. These steel grades also provide good performance and are cold pressed, giving faster production times. Forming and joining are more demanding than with conventional

Safety for vehicle occupants

Most new cars now achieve a five-star rating for Euro-NCAP (European New Car Assessment Programme) performance in protecting vehicle occupants from collisions. In future, further stars may be awarded for other test cases, such as rear impact, roll over or crash compatibility.

The increasing array of crash-test scenarios will require more sophisticated crash structures that take account of a wider range of potential accidents.

To meet the changing requirements placed upon a vehicle to protect its occupants, there have been many innovations in passive safety devices such as air-bags, knee-bolsters and anti-submarining seats. Together these life-saving devices work to protect occupants if they are unfortunate enough to be involved in an accident.

The body structure of modern vehicles has developed from the simple crumple-zone approach of the 1980s to become a sophisticated load and energy management device, providing not only for day-to-day in-service performance, but also for the extreme conditions of a crash event.

As well as contributing to the manufacture of these components, Corus assists vehicle manufacturers and their suppliers in developing materials and application technologies that reduce cost while meeting the increasing demands for safety in ever-shorter development times.

Automotive industry issues: Safety

By using its computer simulation expertise to predict the effects of these changing requirements upon the vehicle structure, Corus is able to define the best materials, manufacturing and assembly methods.

It is anticipated that the increased confidence in virtual testing – as engineering analysis models become more sophisticated – will lead to crash testing of only the worst-case scenarios.

30

Image courtesy of Essex County Fire & Rescue Service

Safety at the roadside

In addition to the demands of vehicle safety, Corus is keen to help improve safety on the roadside by developing ever-more advanced vehicle-restraint systems.

The first of a new set of six parts of standard EN1317 was released in 2004 by the European Commission. This consolidated the previously disparate standards for roadside safety fences and bridge parapets, also known as vehicle restraints. The other parts of the standard will come into force by 2010. Corus is a key contributor to the technical debate that will ensure the new standards address the safety issues on our roads.

Corus has been a vehicle-restraint system manufacturer for more than 40 years, testing and producing the safety fences and bridge parapets that have become a familiar sight on our major road networks. Corus applies its computer-simulation technology to solve the complex problems of redirecting errant vehicles from high-energy collisions with roadside obstructions. The fruit

of this work is a series of products that are already contributing to safer roads.

The Corus portfolio includes products ranging from motorway safety barriers to high-containment bridge parapets.

33

Find out more: www.corusconstruction.com/saferoads

Automotive industry issues: Safety

32

Safety for pedestriansIn the European Union, around 8,000 pedestrians and cyclists are killed and around 300,000 are injured each year in road traffic accidents. In October 2005, the European Union enforced Phase I legislation (2003/102/EC) aiming to minimise pedestrian injuries.

design requirements, is extremely challenging.

Advanced computer simulation capabilities and detailed materials knowledge have enabled Corus to work with OEMs and their Tier suppliers to develop new concepts for vehicle bonnets, wings and bumpers that satisfy these requirements

Phase II legislation is being discussed at the European Commission and should be confirmed in the near future. Initial texts are suggesting more stringent safety targets with an enforcement date of 2010. It is expected that pedestrian safety design will continue to be a significant requirement, being incorporated into new model types very early in the vehicle programme.

Corus is investigating the technological requirements to meet this more demanding legislation.

Vehicles now have to be more compliant to pedestrians and meet legislative impact criteria, protecting leg and head in simulated collisions.

Phase I of the legislation is already posing major challenges for vehicle manufacturers. Pedestrian safety has a significant influence on styling, under-bonnet packaging and structure crushability. Vehicle bonnets, fronts and bumpers must now deform at lower loads over longer distances, requiring additional package space and revised components. Achieving this space and stiffness at the same time as making the vehicle aesthetically pleasing and considering all other

An innovative Corus bumper solution that protects pedestrians’ legs

Table 3: Evaluation of a clutch pedal

Design Advantages Disadvantages Piece Mass cost (euro) (kg)

Steel pressing

Aluminium alloy

High mass, moderate tooling cost, poor NVH

2.81 0.58Recyclable, low parts cost, stiff, robust

Steel fabrication

3.51 0.30Poor recycling, high parts cost, low stiffness, not robust

Low mass, good for complex shapes, good NVH

Plastic injection moulding

2.20 0.39High mass, high tooling cost, not suited to complex shapes

Recyclable, low parts cost, robust, stiff

4.20 0.36High parts cost, poor NVH (noise, vibration and harshness)

Recyclable, low mass, low tooling cost, robust, good for complex shapes

Did you know?Analysis shows that if just 25 key components were converted back to steel from plastics, it would increase vehicle recyclability by five per cent.

35

Wonder material More than 400 million tonnes of steel is recycled globally every year. It is the most widely recycled engineering material in the world. Around 40 per cent of the world’s production of ‘new’ steel is made from steel recyclate. Like water, steel can be recycled over and over again without performance degradation.

End of Life Vehicle Directive (ELVD)

The use of steel for an increasing range of components is helping carmakers to improve vehicle recyclability and meet the demands of legislation.

Carmakers have a real challenge on their hands. In an effort to reduce landfill, the End of Life Vehicle Directive (ELVD) legislation states that from early 2007, 85 per cent of the mass of any new car sold in the EU must be recycled or reused. By the end of 2015 this target rises to 95 per cent.

Corus is working to maximise the benefit of recycling steel, using its materials and engineering expertise.

Advances in steel technology over recent years mean that components like fuel tanks, pedals, engine covers, fluid reservoirs and front-end structures can now revert cost-effectively from plastics back to steel to improve recyclability. Research shows that if just 25 components

Automotive industry issues: Environment

in a modern car were to revert from plastic to steel, it could increase the vehicle’s recyclability by five per cent.

When it comes to car components, sustainability involves finding more cost-effective ways of using recyclable steel. A recent vehicle engineering study by Corus on designs for a clutch pedal in aluminium, plastic and steel demonstrates that improving recyclability need not have an adverse effect on cost or performance (see Table 3 opposite). Carmakers will increasingly need this type of support from materials suppliers as the ELVD legislation comes into force.

34

Find our more: http://ec.europa.eu/environment/waste/elv_index.htm

Source of Table 3: Corus

Ultra Low CO2 Steelmaking (ULCOS)

The steel industry accounts for six per cent of all man-made CO2 emissions and is therefore in the frontline of efforts to combat global warming.

Although typical CO2 emissions per tonne of steel are now around 50 per cent lower than 40 years ago, more needs to be done. This requires both a short-term effort on incremental reduction and a long-term strategy to find innovative ways to reduce carbon gas emissions.

This effort is being spearheaded by the European steelmakers who have launched the Ultra-Low Carbon Steelmaking programme (ULCOS), which is examining a range of radical technologies to reduce the steel industry’s emissions. In addition to the European steel companies, consortium members include other industries, universities and research institutes who bring a fresh perspective to the issues faced by steelmakers.

37

Corus is a major partner in ULCOS whose short to medium term emphasis is on reducing emissions incrementally, wherever this can be achieved in a cost-effective way.

Although more than 80 per cent of emissions from Corus’s integrated steelworks are irreducible process emissions, the combustion-related CO2 emissions are closely linked with energy use. In recent years, Corus has been successful in significantly reducing the amount of energy used to make each tonne of steel. The restructuring of UK operations, which involved rationalising steelmaking activities from six sites in 2001 to four at the end of 2005, has played a substantial part in this.

Find our more: www.corusgroup.com/en/responsibility/environment/

Sustainable solutions

Hexavalent chromium is commonly used in the production of adhesive-coated metals. Corus has developed a unique hexavalent chromium-free adhesive-coated metal called Envirobond™, for use in a wide range of automotive applications.

ELVD legislation demands that carmakers remove harmful substances from vehicles, including hexavalent chromium, lead, mercury and cadmium.

Envirobond™ provides an alternative for components where pre-applied reactivatable adhesives are required, such as weather strips for door linings, sunroofs, bonnets, boots, body side mouldings, brake shims and interior trims. Envirobond™ is capable of meeting the stringent quality requirements demanded by the industry, without any loss of corrosion or adhesion performance. It can be used on a full range of metal substrates for bonding to plastics and rubbers in many automotive applications.

36

Automotive industry issues: Environment

Find our more: www.corusgroup.com/en/responsibility/environment/

Going the extra mileIn recent years, improvements in the selection of raw materials – and better process controls – mean that primary steelmaking by-products now meet strict quality standards. As a result, these by-products are being used as secondary materials in sectors such as cement and chemicals manufacture. This results in non-renewable primary raw materials being conserved.

A good example is blast-furnace slag, a by-product from the production of pig iron in a blast furnace. For years this was considered as waste and ended up in landfill. Corus has optimised its iron-making processes and invested in granulation facilities to generate tightly specified slag products, which are now used as a valuable secondary raw material in the cement industry. This approach helps to conserve non-renewable resources such as limestone, and significantly reduces emissions of CO2.

Table 4: Output from previous VA/VE studies

Vehicle Corus task Saving potential Approx saving/year

£70/vehicle £14mVA/VE Light van

£20/vehicle £3mVA/VE B segment

£30/vehicle £3.6mVA 4x4 chassis

£10/vehicle £2.5mVA C segment

£30/vehicle & 16kg £22.5mVA C segment

£10/vehicle & 10kg £1.5mVA/VE D segment

150kg N/A VA MPV

£50/vehicle & 9kg £7.5mVA C segment

39

Fewer parts mean lower costBy combining their knowledge of Advanced High Strength Steels (AHSS) and automotive engineering, Corus engineers are constantly looking for new applications that will reduce cost and weight for automotive customers.

Weight and cost reductionMore than 25 per cent of all European emissions of CO2 result from the use of transport. One of the ways to reduce fuel consumption and CO2 emissions is to reduce the weight of vehicles.

Automotive industry issues: Weight and cost reduction

38

Door inner

Integrated DP800 reinforcement

Door outer

Corus Automotive has developed a proven approach for reducing cost and weight of both existing and new prototype vehicles, called VA/VE (Value Analysis/ Value Engineering).

The value analysis part of this approach systematically evaluates the gauge, grade and coatings of vehicle body and chassis components, to identify materials-based cost and weight reduction opportunities.

The value engineering part of the process identifies design change

opportunities to reduce tooling and other manufacturing costs, while maintaining or enhancing structural performance.

Using this approach, customers are assured of the optimum deployment of materials to achieve required performances at the lowest practical cost. Some examples of the output from previous VA/VE studies are shown in Table 4 below.

Corus recognises the need for cost-effective, lightweight solutions that do not compromise performance. For this reason, the company strives to use its extensive materials knowledge to develop ideas for extracting the maximum benefit out of the steel used.

As part of its efforts, Corus has developed a one-piece AHSS door concept. The design integrates the intrusion beam, waist rail, lock and hinge reinforcements into a one-piece panel manufactured from DP800-grade steel. The reduced gauge gives a weight saving of 0.65kg/door, while maintaining the equivalent side-impact performance of the conventional design.

Did you know?A Smart Fortwo weighs more than a 1974 Mark I Golf.

Corus Automotive engineers working on a VA/VE subframe study

Source of Table 4: Corus

41

Table 5: Breakdown of 40 years of weight increases (700kg)

Contribution Outcome Comments to weight increase (%)

Latest Polo is the same size as the 1974 Golf

30Longer, wider and taller Vehicle size

Vehicle stiffness contributes to the ‘quality’ feel

25Improved Noise, Vibration, Harshness (NVH) and handling

Vehicle stiffness

EuroNCAP has raised consumer awareness

Safer and moredurable

Vehicle strength

The biggest recognisable change in vehicle quality

15Air Conditioning, NVH, seats

Comfort/refinement

Safety cell improve-ment is included in vehicle strength

5Airbags, pre-tensioners

Occupant safety

The average car now contains more than 20 electric motors

13In car entertainment, electrical

Features/equipment

Includes fuel systems, powertrain and driveline.

17Acceleration, handling and brakesPerformance

Bigger, thicker, exhausts now include catalysts

5Noxious emissions reduced by two orders of magnitude

Emissions

Use of plastics

Use of HSS/AHSS

Plastics and rubber now account for 15% of a vehicle mass

Rapidly increasing over the past five years

Many materials (aluminium, zinc, wood, steel) have been replaced by plastic

Now accounts for over 50% of BIW and closures

(-) 5

(-)5

Total 100

40

Vehicle weight – in decline at last?

Automotive industry issues: Weight and cost reduction

For an average-sized car driven 14,000 miles (22,000 km) in a year, four tonnes of CO2 are emitted. Lighter vehicles mean lower fuel consumption – and trends finally seem to be moving in the right direction. Vehicle weight has been increasing steadily over the last 40 years, as typified by the ‘average’ C segment car (see Fig. 5). Cars in this segment have been getting heavier by five to ten per cent at every model change, mostly driven by safety, stiffness and increased equipment levels. Table 5 shows how this weight increase (of 700kg) breaks down.

The weight increase by segment is compounded by fashion trends – people carriers, 4x4s and performance expectations. The popularity of these larger vehicles has slowed the rate of reduction of CO2 levels.

Vehicle weight – the good news• Social and economic pressures are now reversing the trend toward large vehicles.• Most cars are now achieving 5 stars in the Euro-NCAP tests.• Larger cars (especially in the luxury ‘E’ segment) are levelling out on size and weight.• In the C and D segments the rate of increase of vehicle weight is slowing and looks likely to reverse in the next five to ten years• The European Commission plan to ensure a new car average of 120g CO2/km by 2012 will result in strong competition and weight reduction in the high-volume B and C segments.

Find out more: www.acea.be/node

Cost effective lightweighting by the use of Advanced High Strength Steels (AHSS) will allow vehicle manufacturers to reverse model on model weight increases without recourse to expensive or environmentally unsound solutions.

The successful introduction of AHSS by European steelmakers, demonstrating material performance and supplier support through Early Vendor Involvement (EVI) and innovation, will ensure steel remains the first choice material for automotive structures for the foreseeable future.

Fig. 5 Weight increase year by year C segment car

Source of Table 5: Corus

Diagram courtesy of Thatcham

43

Services to support engineering, design and production quality Carmakers are increasingly seeking access to in-depth materials knowledge to assist in the selection of cost-effective materials, and to ensure a smooth transition from the design and development stages of carmaking into full production.

That’s why the Corus team of design and engineering specialists (mostly recruited from the automotive industry) work with their carmaker customers to select materials and find ways to efficiently manufacture vehicle structures and components at the lowest weight and cost.

High-technology engineering analysis capabilities are used to, for example, review fatigue performance of proposed parts, including advanced methods to assure fatigue performance in critical seam and spot-welded joints. Technical help services like this, when applied early in the concept and design stages of car development, can demonstrate the business case for a wide range of components, including body

structures, chassis and suspension parts, hydroformed sub-frame parts and driveline components. Corus Technical Services also offer press shop support – bringing many years of experience to bear in helping to troubleshoot and ensure that mass-production presses turn out components of acceptable and consistent quality.

Corus Automotive Service Centres offer a range of pre-production services to make 1D and 2D tailor-welded blanks, using CO2 laser welding cells. Corus also uses specialised lasers which deliver intense light via fibre-optic cables, meaning that complex curved welds are possible.

Find out more: www.corusautomotive.com/en/products/engineering_services/

Quality and serviceEvery automotive component made from steel is designed and built to deliver a reliable and predictable service life. Steel’s mechanical properties of strength, cleanness and surface finish must be reliable if carmakers are to create their products cost effectively.

Manufacturing qualityAs soon as decisions are made about which steel grades to produce, product quality becomes a priority. Careful selection of raw materials, steelmaking process and refinement and finishing processes all improve the quality of Corus steel products. Corus mills take great care to ensure that the dimensional, surface finish, strength and mechanical properties of every steel product that leaves its plants are within required tolerances.

Distribution qualityOnce steel products have been made, it is essential that their hard-won quality is not compromised during the delivery process. One example of the way Corus controls

Automotive industry issues: Quality and service

the delivery quality of its steel is in its wire rod mill. Wire rod is used to manufacture an incredible range of automotive components including tyre reinforcement cord, valve springs, headrest supports, air bag and seatbelt wire and windscreen-wiper components. Scratches on the surface of the rod can cause it to break during wire drawing, creating unacceptable production downtimes. As part of a £14m investment in its rod mill, Corus has introduced a state-of-the-art automated warehouse. Here, coils are protected from damage by storage in individual compartments, and manual handling is virtually eliminated. The results have been instant, with incidences of damaged rod dramatically reduced.

42

Image courtesy of Xtrac

Consistent delivery of high-quality material and service

Corus materials and vehicle engineering expertise have helped to deliver weight and cost benefits to UK-based manufacturer LDV.

LDV approached Corus to undertake a number of studies to help identify weight-reduction and vehicle-assembly improvements prior to the launch of its new MAXUS range of light commercial vehicles. Corus was able to offer the support of its Automotive Engineering Group, based in Coventry, which specialises in developing innovative vehicle-engineering solutions using the latest thinking in materials and manufacturing technologies.

Corus carried out gauge optimisation studies to help identify weight-saving opportunities, while maintaining the vehicle’s body stiffness and performance characteristics. The studies resulted in a 15kg per vehicle weight saving, without detriment to the robust body and chassis structural targets for MAXUS. This was no easy task, as MAXUS is 20 per cent stiffer than the company’s existing range.

45

Clearly, the ideal time to employ this unique approach is before vehicle launch, so that savings can be introduced before capital expenditure for production tooling has begun.

Find out more: www.corusautomotive.com/maxus

Expertise optimises con-rod manufactureCarmakers are increasingly turning to companies like Corus to develop innovative solutions that help designers to reduce component weight, improve service life and cut manufacturing costs

44

Smethwick Drop Forge (SDF), the UK’s leading forger of connecting rods for passenger and commercial vehicles, approached Corus for help in developing its con-rods. The company needed to satisfy the ongoing demand from customers for lighter-weight components, improved fatigue performance and reduced machining – taking costs out of the manufacturing process on current production components.

Corus has extensive expertise in computer modelling techniques and in-depth knowledge of the application of different steel grades, which it used to reduce the weight of SDF’s con-rods by up to 15 per cent.

This lighter component design in turn improves engine efficiency and contributes towards meeting stringent environmental legislation. The improved machining responses were delivered without sacrificing the strength or durability of the part.

Corus in actionThe case studies in this section illustrate how Corus combines its materials knowledge, automotive-engineering expertise and manufacturing innovation to offer its customers unique solutions to their specific needs.

Find out more: www.corusautomotive.com/sdf

Corus in action: Case studies

Commenting on the collaboration, Mark Adams, Managing Director SDF, said: “By partnering with Corus and utilising their material knowledge and expertise in computer simulation techniques, we have been able to carry out many iterations in a short space of time to determine optimum con-rod design for our customers.”

Did you know?A steel body panel begins life as a 250mm-thick cast slab, which is then hot rolled to reduce it to a 3mm-thick strip steel. This is then cold rolled to 0.8mm or less.

47

Tubular hydroform components for Discovery 3

Find out more: www.corusautomotive.com/hydroforming

Collaboration cuts cost and weight

looked at opportunities to reduce the gauge, and therefore the weight of the panel, while ensuring that the complex panel shape was feasible to press.

A detailed parts-integration study of the rear-floor panel showed that it was possible to use just one part instead of the originally planned two, allowing Ford to save on tooling, process and manufacturing costs.

By utilising the superior properties of dual-phase steel, it was also possible to down-gauge the heel board and rear cross members from the traditionally specified High Strength Low Alloy (HSLA) grades, while retaining the same side-impact performance.

46

Pre-production studies by Corus enabled Ford to reduce the costs of manufacturing its new Ford Galaxy – at the same time as reducing the vehicle’s weight.

Find out more: www.corusautomotive.com/galaxy

Corus in action: Case studies

With the growing use of high-tech steels in today’s automotive press shops, it is increasingly important for carmakers to fully understand how a material will deform and flow during the pressing process, in order to ensure capability, quality and performance in the finished component.

Working closely with Ford engineers at Merkenich, Germany, a collaborative project was undertaken by Corus on the new Ford Galaxy. This included feasibility, parts-integration and cost and weight reduction studies on the rear floor, rear cross member and heel kick panels.

The study on the rear-floor panel

Precision tubes are delivering cost-effective hydroformed components that improve strength and stiffness while reducing weight.

The Corus precision tubes facility in Zwijndrecht, the Netherlands, is supplying high-quality tubes to specialist German hydroformer Finow Automotive Eberswaldle, based in Berlin. Finow Automotive in turn supplies hydroformed components to Chassis Systems Ltd (CSL), based in Telford, UK, the joint-venture business created by DANA and GKN to produce the chassis for Land Rover’s highly acclaimed Discovery 3.

The demand for lighter components remains a primary driver in the automotive industry. Tube hydroforming is one of the new enabling technologies that has the capacity to deliver cost-effective mass-produced solutions and is

increasingly being used by vehicle manufacturers. Hydroforming can be used by automotive engineers to optimise future car designs with fewer components, helping to increase the strength and stiffness of critical parts, while contributing to reduced vehicle weight and therefore lower fuel consumption and CO2 emissions.

The Corus Tubes Automotive and Engineering business has achieved registration to the new ISO/TS 16949:2002 quality-approval standard. Until recently, car manufacturers had focused on their own quality standards. TS 16949:2002 is a breakthrough because it represents a consensus among most of the world’s largest carmakers and is a starting point in the harmonisation and globalisation of designer-specified standards.

Aimed primarily at Tier One suppliers, TS 16949:2002 is a technical specification developed and supported by vehicle manufacturers in Europe, America and Japan. It will help to define quality system requirements for the global automotive supply chain.

the final cam profile. This saves a considerable amount of time in setting up and processing the camshafts.

Lars Andersson, Corus product manager, said: “This contract demonstrates Corus’s commitment to helping the supply chain enhance productivity and improve component performance.”

Gearing up for spring market

Corus has developed a grade of wire rod suitable for manufacturing the most demanding and quality-critical automotive springs.

49

Find out more: www.corusautomotive.com/springs

Clean steels for critical engine components

High-quality camshaft blanks from Corus save time and boost productivity for Volvo Trucks.

48

Find out more: www.corusautomotive.com/volvo

Corus in action: Case studies

Corus has a contract to supply Volvo Trucks with precision-machined camshaft blanks for use in the manufacture of critical engine components.

Corus supplies the camshaft blanks directly to Volvo Trucks’ manufacturing facility in Skovde, Sweden. The blanks, which have been faced and centred, can be placed directly onto Volvo’s CNC machining cell, which produces

Valve springs are in constant motion when in use, making them one of the most demanding applications for any steel. Valve-spring steel must be super-clean and meet very strict quality criteria. Experience in making other super-clean steels for automotive applications has enabled Corus to meet the significant challenge of manufacturing this premium grade.

Manufacturing valve-spring steel requires low levels of non-metallic inclusions in the surface layers of the steel and tight control over other metallurgical parameters, such as surface cracks and decarburisation. A lengthy development process at Corus, employing carefully controlled casting and rolling techniques, has resulted in the successful production of an automotive spring-grade steel.

This steel is now undergoing rigorous fatigue tests for valve-spring applications. As these trials continue, Corus is in a position to supply material for other critical automotive spring applications, such as clutch, suspension and transmission springs.

51

to bring a new car to market. Therefore, the ability to choose the right materials for the task, based upon reliable engineering analysis and properties data, is critical to an efficient development cycle.

Many aspects of a part’s performance must be considered: How light can it be made? Will it ‘form’ correctly into an accurate shape? Will it split or tear during manufacture? Can it be joined with other parts? Will it corrode? How will it be dismantled at the end of the car’s life? Will it be durable in service? Can one material be substituted for another?

Corus Research, Development and Technology operations offer the in-depth knowledge, experience and facilities needed to provide answers for all of these questions.

Design and engineering Corus Automotive offers advanced technical services to help customers select the right materials. Corus services and expertise in structural performance optimisation for crashworthiness and durability, for example, enable rapid evaluation and characterisation of material properties for proposed or in-service components. Strength and stiffness, fatigue strength, high-speed impact properties, machinability and dent resistance must all be considered.

We use our experimental facilities to characterise materials and performance and generate specific experimental data for use by customers. Extensive use of computer-aided engineering design and analysis methods is made by Corus in areas such as Value-Analysis, Value-Engineering and other advanced methods to prove out a design’s durability, weight, manufacturing feasibility and true cost.

From these activities come new methodologies, such as the development of an integrated weld optimisation tool to improve the placement and length of seam welds on chassis subframes.

Studies such as ‘design for dismantling’ are also carried out to assess how easily materials can be recovered and re-used once the car has reached the end of its life.

Find out more: www.corusautomotive.com/automotive_applications

Steel R&D technologies

Carmaking has a high-technology image for good reason – over the past 100 years, almost every aspect of a car’s function has either been enhanced or newly introduced, in many cases as a result of new materials technologies.

Today’s carmakers and their suppliers face significant technical challenges in proving out the benefits and implementation of the higher performance grades of steel that they have been seeking. R&D expertise and supporting services are essential to optimise the use of the grades and gauges of steel required for existing and new car product lines.

These are all areas in which the best steelmakers are involved, in partnership with their carmaker customers.

A technology commitment Corus invests £75m every year in research and development, looking at materials science, steel-manufacturing technologies and specific application technologies.

Steel R&D technologies

More than 900 researchers and industry experts at facilities in the UK and the Netherlands combine world-class innovation, cutting-edge technology and market knowledge, to offer Corus customers a truly unique combination of materials and application solutions.

Corus collaborates with universities, research institutes and its customers, to deliver innovative steel solutions and services for a constantly changing world.

Optimum materials selectionChoosing the most cost-effective materials and manufacturing processes to make a new car can mean the difference between financial success and failure. Added to these challenges is the constant pressure to reduce the time taken

50

Solutions for a technology-driven marketplace

Top - Standard crash analysis

53

Fig. 7

Bottom - Crash analysis including formed properties in subframe extension

Fig. 6 Simply using the standard factory-coil material properties can introduce inaccuracies in the prediction of intrusion in the subsequent crash analysis. F2C® improves accuracy by including in the crash analysis the predicted forming-induced strength and thickness changes, introduced by the manufacturing steps. This gives more reliable simulation results and provides opportunities to reduce weight.

Fig. 7 This illustrates the differences in predicted intrusion performance of a vehicle front-end structure in a crash, which resulted when the formed properties were/were not included in the crash analysis. These subtle inaccuracies can easily mean the difference between a pass and a fail for the finished car design.

Steel R&D technologies

Steel R&D technologies

52

Applied research expertiseResearchers at Corus RD&T in IJmuiden, the Netherlands, and Rotherham, UK, offer advanced material data models to engineers in car companies who are charged with proving out formability. Tools like this are essential to simulate new design ideas and support decisions about which grades and thicknesses of steel to use in which parts – the virtual prototype. Like every other material, every gram of steel needs to justify its use in the modern car

It is not just the applications for steel sheet that are researched, new steel chemistries for parts that must be highly durable at high temperatures such as engine valve-spring steels or the steels used to make transmission gears are also studied. New steels that are dimensionally stable during carburising (hardening) are just one example of this work.

Technologies for manufacturabilityDeep drawing, bending, roll forming, hydroforming and warm/hot-stamping, are all processes that can change the physical properties of a material. For components to become truly production-feasible, it is essential that carmakers have a solid understanding of how steel will behave as it are formed into shape within the press and other tools.

Enabling a smarter use of materialsWith growing use of high-tech steels and greater part complexity, Corus is increasingly called upon to help optimise the production of stamped parts on existing equipment. As virtual-prototype simulation models are now being used to produce products with shorter development times, it is essential to understand the material properties for those critical components that must withstand, for example, in-service crash and durability loads.

Corus has developed the unique and advanced Corus-Vegter material model. When combined with other specialist analysis techniques, including F2C® (Forming to Crash), F2F® (Forming to Fatigue) and F2S® (Forming to Strength), much more accurate crash and durability simulation results can be achieved – enabling a smarter use of the available material and design space. (See Fig. 6 and Fig. 7 opposite).

Find out more: www.corusautomotive.com/technical_papers

True

str

ess

(MP

a)

True strainForming strain

Strength increase

Source of Fig. 6 & Fig. 7: Corus

Fig. 6 Material strength increase due to forming strain

55

Coating technologiesKnowledge and application of surface technology has been used by Corus to improve corrosion resistance, enhance coating performance and engineer the surface appearance of metal parts for many customers over the years.

This expertise enables Corus to design the surface and substrate of its products as an entire system, delivering cost-effective performance enhancement. The company’s knowledge of its customers’ coating processes is a critical factor, enabling Corus to support them in optimising their own processes to achieve the best end-product properties. With the advent of alternative fuels and fuel-cell power generation, this is an area of metals technology that is expected to become increasingly important.

Welding and joining technologiesThe ability to make reliable metal joints is an essential technology in the assembly of a vehicle Body in White. Corus researches most joining techniques used in car manufacturing, from riv-bonding and laser welding for steel to fluxless aluminium laser-brazing. Our researchers also use finite-element modelling to study weld optimisation and the effects of different chemistries and coatings on joinability and post-weld corrosion proofing. Corus can also help its customers with weld-facility implementation.

Find out more: www.corusautomotive.com/automotive_applications

Steel R&D technologies

Steel R&D technologies

54

Technologies for pilot productionCorus has developed advanced tools and techniques to validate and troubleshoot formability (including springback) in stamping, press-tool geometry review and tube-forming feasibility.

To speed this process, Corus has co-developed a portable troubleshooting tool for strain assessment, called Phast™. This is used to understand and visualise how a material flows as it is stamped into physical parts. A second, complementary technology, called In-Form™, uses a state-of-the-art laser device to scan and capture the 3D surface of a part or stamping tool. This enables accurate geometry data from the actual tools that will be used to be fed into a forming simulation model. Together, these tools ensure accurate press performance and low scrap rates once full-scale production begins.

Technologies to enhance finish qualityA great deal of the image projected by a car depends upon the accuracy of part dimensions, the quality of joints and the corrosion-resistance and adhesion properties of its surfaces. New coatings and methods for joining metals have been a key area of Corus research for many years.

Find out more: www.corusautomotive.com/automotive_applications

Did you know?Steel sheet used on the outer panels of a vehicle is around 0.7mm thick – about as thick as a fingernail.

Graduate opportunities

Looking to the future: Graduate opportunities

57

RecruitmentCorus is constantly looking for passionate, dedicated staff to ensure it continues to deliver a world-class service to customers and maintains its cutting-edge research. To this end, Corus recruits personnel at all levels, from engineers to account coordinators and from logistics professionals to graduates. The scope and size of the company allows it to offer interesting, challenging and dynamic careers.

In 2006, 120 graduates in the UK and more than 140 from the Netherlands began their careers with Corus. In the Netherlands, graduates go straight into a permanent role, at the same time taking part in a talent-development programme which offers wider training awareness and career orientation.

Depending on performance, UK graduates can enter a substantive position at any time from six months to two years after their start date. All UK entrants are encouraged to take part in a Corus five-year training plan, on-the-job training, chartership/professional qualifications and to develop a strong relationship with a mentor.

Postgraduate sponsorshipCorus also sponsors approximately 100 postgraduate students per year in a variety of technical and engineering programmes, typically in Engineering, Metallurgy and the Environmental sciences. The majority of these are supported by grants from the Engineering and Physical Sciences Research Council (EPSRC). The two main routes to postgraduate study are engineering doctorate research and industrially supported PhD projects.

ApprenticeshipsCorus apprenticeship schemes lead to vocational and academic qualifications, following study at a local further-education college. Recruits are provided with a first-class training programme and receive an attractive salary or bursary.

Apprentices have the opportunity to achieve senior levels within the company, as well as receiving additional education and training qualifications.

Find out more: www.corusgroup.com/en/careers/recruitment

Looking to the futureThe next generation

As a major supplier to the European automotive industry, Corus recognises the importance of supporting and inspiring the automotive designers and engineers of the future.

Formula StudentCorus frequently sponsors student engineering teams entering the International Formula Student programme.

Formula Student provides the next generation of automotive engineers with a valuable insight into the engineering and project-management processes of taking a race car from design through manufacture and, ultimately, to competition. Students gain access to the latest material, technology and industry techniques. Such engineering experience often proves invaluable after graduation when students enter the automotive and other industries. Some of Europe’s leading student race teams – from the universities of Birmingham, Delft and Warwick – have been supported by Corus in recent years.

Looking to the future: The next generation

56

Find out more: www.corusautomotive.com/en/news/events/

Design showsTo bridge the gap between the disciplines of advanced metal engineering and leading-edge product design, Corus has sponsored the Coventry University Automotive MA Design Show and automotive design projects at the Royal College of Art.

These activities help to create opportunities for future car designers as they meet influential industry figures, potential mentors among today’s carmakers and their contemporaries in the fields of automotive manufacturing and journalism. The possibilities that new materials can offer to the designer are discussed in an open forum with leading industry figures such as Patrick Le Quement of Renault or Peter Horbury of Ford.

59

processes. Individual steel companies then worked directly with their customers to help implement these materials and technologies to deliver real benefits.

Secondly, possibly because so much of the modern world depends on steel, the benefits are easy to underestimate. Formability, strength and ease of joining are significant advantages over competitor materials. The past 15 years have seen the development of stronger steels with improved formability, together with the complementary technologies to process and assemble them within high-volume vehicle manufacturing plants. Computer analysis tools have been developed to model the properties and application of these new steels more accurately, which has given vehicle manufacturers the confidence to implement them in their new designs.

New vehiclesAbove all else, the conflicting demands of consumers, legislators and global competition require cost-effective solutions. The sharpening of emissions legislation will spark a drive for more efficient vehicles. This means that alongside the complexity of powertrain solutions, from hybrids to hydrogen, the search is on for simplicity – de-contenting, integration of electronic systems, miniaturisation of components – to increase occupant space while making vehicles smaller and lighter.

Looking to the future

Looking to the future: Looking to the future

58

With new innovations, technology and steel grades constantly being developed, steel looks set to retain its status as the material of choice for carmakers worldwide.

History can teach us much about what might happen in the future. When the oil crisis struck in 1974 – in the early days of automotive industry globalisation – everyone agreed that cars would have to get lighter. Instead, cars have almost doubled in weight since then, due mainly to increases in size, added features and better safety.

For automotive materials, the introduction of the Audi A8 about 15 years ago was a seminal event that single-handedly opened up the materials debate. Since then, the debate has been about aluminium versus steel. At the time, many viewed aluminium as the material of the future, with steel playing a decreasing role in vehicle design and development. However, today steel still dominates the vehicle structure – so what happened to change the predicted course of events?

CollaborationFirstly, the global steel industry recognised the challenge. It realised that steel was perceived as traditional, rather than a material for the 21st century, and embarked on one of the most successful collaborative development and communications programmes of modern times – the UltraLight Steel Auto Body programme (ULSAB).

This programme, initially launched in 1998, demonstrated and promoted the benefits of existing materials and processes, showing that intelligent use of steel could readily provide cost-effective vehicle weight savings. Subsequent work on closures and suspension systems proved just as positive, as did the final project, Advanced Vehicle Concepts (ULSAB-AVC). This heralded the availability of Advanced High Strength steels and supporting

New processesSteel will play a major role in this shift. We can expect the development of even stronger steels with improved formability to enable more complex panel shapes to be achieved. This will result in parts integration, reducing cost and increasing the value attractiveness of steel. Computer analysis tools will improve, helping to model changes in the mechanical properties of these new steels during panel manufacturing – which is essential for the design process. Modelling of joining processes will improve too, leading to faster, more effective joining technologies.

New materialsWith any prediction of the future, however, there is always the possibility that technology may be introduced that will completely change the course of events. This may enhance the cost-benefit analysis for aluminium, magnesium or composites. However, the steel industry is well advanced with its own breakthrough material – TWIP (Twinning Induced Plasticity) steel. This new breed of steel combines ultra high strength with incredible ductility. It is being developed in the research departments of the steel industry right now, and it will not be long before engineers have the opportunity to incorporate this new steel into their designs. The future is probably closer than we think.

About Corus: Sources of further information

61

Corus AutomotiveSources of further information

You can access more information about Corus and its automotive products and expertise through a number of sources.

Find out more: www.corusautomotive.com

About Corus

Corus is one of the world’s largest steel producers. Its operations are organised into three principal divisions: Strip Products, Long Products and Distribution & Building Systems.

About Corus: Company profile

Corus employs approximately 41,000 people, with the majority based in the UK, the Netherlands and other Western European locations.

StrategyThe company’s strategy is focused on developing a strong and sustainable competitive position for its carbon steel in its Western European markets and improving its exposure to lower-cost, higher-growth regions.

SteelThe Corus Group produces carbon steel at three integrated steelworks in the UK, at Port Talbot, Scunthorpe and Teesside, and at IJmuiden in the Netherlands. Engineering steels are produced in the UK at Rotherham using the electric arc furnace method. Corus also has processing facilities in North America and Europe.

SalesCorus has many sales offices, stockholders, service centres and joint venture or associate arrangements for the distribution and further processing of its steel products. These are supported by various agency agreements. There is an extensive network in the EU,

while outside Europe Corus has sales offices in around 30 countries, supported by a worldwide trading network.

BrandCombining its global expertise with local customer service, Corus offers value, reliability and innovation. The Corus brand represents a mark of quality, loyalty and strength.

ManufacturingIn 2005 approximately 60 per cent of Corus’s steel production was rolled into hot-rolled coil. Most of the remainder was further processed into sections, plates, engineering steels or wire rod, or sold in semi-finished form.

Approximately 35 per cent of hot-rolled coil was sold without further processing to cold-rolling mills and coating lines, with the remainder transferred to Corus tube mills for the manufacture of welded tubes.

MarketsPrincipal end markets for Corus steel products are the construction, automotive, packaging, mechanical engineering, electrical engineering, metal goods, and oil and gas industries.

60

Company profile

Find out more: www.corusgroup.com

In printemotion magazine is focused on Corus customers in the automotive industry, reaching 15,000 managers and technical specialists twice a year. It includes guest articles discussing trends in the industry that affect the use of steel in car design and engineering, technical developments in materials and manufacturing techniques, and other articles of interest to anyone selecting materials for automotive applications. Back issues of emotion magazine can be found at www.corusautomotive.com/news/emotion_magazine/

If you would like to receive future copies of emotion, please email your details to: emotion@corusgroup.com

OnlineAt www.corusautomotive.com you can find more detailed information about Corus products, services and technology, as well as press releases, data sheets, technical information and further contact details.

63

Elongation The amount of permanent extension in a component under stress, usually described as a percentage of the initial length.ELVD End of Life Vehicle Directive: a European law that requires an increasing percentage of a vehicle to be recyclable. Euro-NCAP European New Car Assessment Program: the European automobile safety organisation providing motoring consumers with an independent assessment of vehicle safety performance. It awards stars for front and side impact performance, as well as pedestrian safety.Exothermic A chemical reaction that gives off heat. For example, the conversion of iron to steel using oxygen generates a large amount of heat. The resultant molten steel is three or four hundred Celsius hotter than molten pig iron.Fracture splitting A specialised manufacturing process in which the precision fracturing of a machined component results in matching, self-locating, surfaces.FEA Finite Element Analysis: a computational method of stress calculation in which the component under load is considered as a large number of small pieces (‘elements’). The FEA software is then able to calculate the stress level in each element, allowing a prediction of deflection or failure.Ferrite See ‘Phase’.Galvanise Coat with zinc, either by electroplating, or (more commonly) by dipping into molten zinc. Since the 1980s, most automotive strip steel has been supplied galvanised for optimal corrosion protection.Grain All steels are polycrystalline – made up of minute crystals known as grains. The size, shape and crystalline alignment of these grains are a key to the performance of steel.Hot rolling Reducing the thickness of strip steel by rolling at elevated temperature, mostly used in thicker gauges for automotive applications.HSLA High Strength Low Alloy: steels that generally contain small amounts of highly effective alloying elements such as titanium, vanadium or niobium in amounts of less than 0.1 per cent.HSS High Strength Steel: steel with yield strength between 220 and 550MPa.Hydroforming The use of pressurised fluid to change the shape of a metal sheet or tube.IF Interstitial Free: steels without the strengthening effect of interstitial elements such as carbon and nitrogen, making them very formable with low strength. These are manufactured by the addition of titanium or niobium, which form compounds with carbon and nitrogen.Interstitial The spaces between atoms are known as interstices. Atoms of carbon and nitrogen that are small enough to fit into these spaces are known as interstitial atoms. They strengthen the steel by preventing layers of atoms sliding past one another.IS Isotropic Steel: strip steel with both chemistry and manufacturing processes specifically designed to give the same mechanical properties in any direction along the length or across the width of the strip.Martensite See ‘Phase’.

Glossary of terms

62

Glossary

AHSS Advanced High Strength Steel: any steel with high levels of both strength and formability.Annealing Heating to and holding at a suitable temperature and then cooling at a suitable rate to remove the effects of work hardening. This facilitates further cold working.Austenite See ‘Phase’.Bainite See ‘Phase’.Bake hardening Steel grades that exhibit an increase in hardness (and therefore strength) when heated to a relatively low temperature, typically in an automotive paint-bake oven. For the bake-hardening mechanism to work the steel has to be work hardened.BIW Body In White: the main structure of a vehicle, usually made of steel pressings welded together to make a strong and stiff frame.Boron steel See PHS.BOS Basic Oxygen Steelmaking: process for converting liquid pig iron into steel, excess carbon being removed by reaction with oxygen. ‘Basic’ here means that the reaction takes place under alkaline conditions.Carburising Surface hardening by diffusion of carbon atoms.CMn Carbon Manganese: steels with carbon and manganese as the principal alloying elements. Mn is the chemical symbol for manganese, not to be confused with Mg (magnesium).Chassis Most cars built before the 1950s were constructed using a separate chassis frame and body. Nowadays, ‘chassis’ refers to the components (subframes, suspension, etc) that connect the BIW to the engine, steering and wheels.Closure A panel attached to the Body In White, such as doors, bonnet and boot. Closures are usually hinged, although some vehicle manufacturers include bolted-on panels, such as front wings.Cold rolling Reducing the thickness of strip steel by rolling at ambient temperature, mostly used in thinner gauges for automotive applications.Continuous casting Non-stop manufacture of steel by pouring liquid steel into a mould, which is a water-cooled copper or ceramic jacket.Drawing A method of forming steel into complex three-dimensional shapes in a press, the metal being pulled (‘drawn’) into the tool where it is stretched into shape.Dual Phase (DP) Steel composed of ferrite and martensite phases. (See ‘Phase’).EAF Electric Arc Furnace: uses electric current to melt scrap steel. The molten steel formulation can then be modified, with alloying elements added as required to produce a wide range of steel grades. Elastic limit The maximum stress to which a material may be subjected and yet return to its original shape and dimensions upon removal of the stress. (See ‘Yield strength’).

65

r-value A measurement of the resistance to thinning of sheet metal during forming processes.Roll forming A process for producing prismatic shapes in steel sheet, the sheet being progressively bent and folded by passing through a series of profiled rollers.Strain The amount a component stretches when a stress is applied. Strain is dimensionless: 100 per cent elongation equals a strain of one.Stress The applied force divided by the cross section of a component, measured in N/m² (= Pascal, Pa). Note: these units are the same as the units for pressure. Indeed, stress may be considered as the pressure applied to a component.Substitutional Large alloying atoms (eg. phosphorus and manganese) take the place of, or substitute, an iron atom – unlike small alloying atoms, which are positioned between the larger iron atoms (see ‘Interstitial’).Tensile strength Also called the ultimate tensile strength (UTS). The stress at which a material breaks.Temper rolling After annealing, strip steel is given enough cold rolling to take it beyond the yield point, resulting in more controllable stretching during subsequent forming processes and a better surface finish.TRB Tailor Rolled Blank: steel sheet cut to a size ready for pressing (i.e. ‘blanked’) where the blank has been rolled to give varying thicknesses along its length.TRIP Transformation Induced Plasticity: steel that contains a small percentage of phases (see ‘Phase’) that change to a harder phase (usually austenite transforming to martensite) during the forming process. The formed steel therefore has a much higher strength.TWB Tailor Welded Blank: steel sheet cut to a size ready for pressing (i.e. ‘blanked’) where the sheet has been welded together from smaller pieces of steel of varying gauge and/or grade.TWIP Twinning Induced Plasticity: steel that has high levels of manganese is austenitic (see ‘Phase’) at ambient temperature. The crystalline structure of austenite results in the occurrence of millions of pairs of crystalline faults known as twins. These twins allow for unusual levels of formability in Ultra High Strength Steel.UHSS Ultra High Strength Steel: any steel grade with a yield strength of 550MPa or greater.Work hardening The increase in the strength of a metal as it is stretched or otherwise formed.Yield strength The stress at which a material will permanently stretch or deform. Below this stress the material will return to its original shape and size once the stress is removed (see ‘Elastic limit’).Yield point The start of yielding in steel may be accompanied by a sudden drop in strength. This is known as the yield point and is undesirable in steel for automotive pressings (see ‘Temper rolling’).

Glossary

64

Mild steel Low-strength steels containing low levels of carbon and insignificant amounts of alloying elements.Modulus The ‘stiffness’ of a material. Calculated by measuring the stress on a test sample and dividing by the strain. Since strain is dimensionless, the unit of modulus is therefore the same as stress (N/m² or Pa). Some examples of moduli: GPa Steel 207 Aluminium 69 Polyethylene 1 Diamond 1000n-value A measurement of the work hardening (strengthening) of metal sheet during a forming process.OEM Original Equipment Manufacturer: in the automotive industry, this refers to a manufacturer of vehicles that provides the original product design and materials for its assembly and manufacture.Pearlite See ‘Phase’.Pig iron Iron direct from the blast furnace, containing high levels of carbon and other impurities. Originally sand-cast into a row of blocks, having the appearance of a sow feeding her piglets – hence ‘pig’ iron.Phase Steel can exist in a number of crystalline forms and combinations of crystalline forms. These are known as ‘phases’. Here are some of the most common:• Austenite: A non-magnetic structure usually found in stainless steels and TWIP steel. • Bainite: Ferrite containing needle shaped iron carbide (Fe3C) crystals – tough and hard.• Ferrite: Iron containing a small amount of carbon in solid solution. The softest form of steel.• Martensite: Excess carbon (‘supersaturated’) results in a distorted crystalline structure and the hardest form of steel.• Pearlite: Alternating layers of ferrite and iron carbide. When viewed under a microscope it has the appearance of mother-of-pearl, hence ‘pearl’ite.PHS Press Hardening Steels (also: hot-formed steel, die-quenched steel, boron steel) a grade of steel that can be processed at high temperature by heating in a furnace and pressing while still hot using a cooled tool. The rapid cooling rate transforms the microstructure to 100 per cent martensite (see ‘Phase’). PHS steels contain boron for optimum hardenability.Pickling An acidic-dip process for removing oxide (‘scale’) from the surface of hot-rolled steel sheet.Rephos Rephosphorised steel: steel that contains phosphor as the main alloying element. Known as Rephos since the high levels of phosphor in pig iron are removed along with other impurities in the BOS process, but phosphor is then added during secondary steelmaking.

Glossary of terms