FERROUS AND

NON-FERROUS ALLOYS

Alloys

Ferrous(Iron based )

Non-ferrous(No-iron content)

Engineering Materials

Metals

Ferrous

Iron

Steel

Pig iron

Cast iron

Wrought iron

Non-Ferrous

Copper & Alloys

Aluminium

Zinc

Tin

LeadNon-Metals

Rubber

Plastics

Resin

FERROUS METALS AND ALLOYS

What is a ‘ferrous metal’ or ‘ferrous alloy’? It is simply a metal or alloy that contains Iron

(the element ferrous) as the base (starting) metal.

26th element Iron or Ferrous 55.85 Atomic Mass

GENERAL CATEGORIES OF FERROUS METALS AND ALLOYS

Carbon and alloy steelsStainless steel Tool and Die steelCast IronsCast Steels

**Ferrous tools first appear about 4000 to3000 BC, made from meteoritic iron.

Real ironworking started in about 1100 BCin Asia Minor, and started the Iron Age.

PRODUCTION OF IRON AND STEEL

RAW MATERIALS FOR PRODUCTION

Iron Ore

Limestone ----------

Coke

IRON ORE

Abundant, makes up 5% of earth’s crust Is not found in ‘free state’, must be found in rocks

and oxides, hence Iron ore. After mining, the ore is crushed and the iron is

separated, then made into pellets, balls orbriquettes using binders, such as water.

The pellets are typically 65% iron, and about 1” indiameter.

COKE

Coke is formed by heating coal to 2100*F (1150 C),then cooling it in quenching towers.

You need more than Iron? Why coke isused…1. Generates high heat, needed in order forchemical reactions in ironmaking to take place.2. Produces CO (carbon monoxide) which reduces

iron-oxide to Iron.

LASTLY, LIMESTONE

Limestone (calcium carbonate) is used to removeimpurities.

When the metal is melted, limestone combines withimpurities and floats to the top of the metal, formingslag.

The slag can then be removed, purifying the iron.

Ferrous alloys

Steels (C% is <2.1)

Cast irons (C% is >2.1)

Ferrous alloys can be broadly classified into 2groups:

1. Steels (C% is <2.1)2. Cast iron (C% is >2.1-6.67)Steels have carbon in the combined form

(austenite, cementite etc.)Cast irons have carbon in the free form as

graphite These ferrous alloys are not only iron and

carbon alloys, few other alloying elements arealso added for special properties

STEELS

Steels can be classified in many ways, the basic classification of steel according to:

Types of steel based upon deoxidization process Carbon content Grade Method of manufacture Applications Standard institutions

CARBON STEELS

Low alloy

Low carbon

High carbon

High alloy

Tool Stainless

Medium carbon

LOW CARBON STEEL

These steels contain less than about 0.25 wt% C These unresponsive to heat treatment because of

very less amount of martensite Can be strengthened by cold work Microstructures consist of ferrite and pearlite

constituents these alloys are relatively soft and weakbut have outstanding ductility and toughness; inaddition, they are machinable, weldable, and, of allsteels, are the least expensive to produce

ApplicationsBridges, towers, support columns in high-rise

buildings, and pressure vessels

MEDIUM CARBON STEEL

These steels have 0-25 – 0.6 wt% C It is stronger than low carbon steel but less

tougher than it These alloys may be heat-treated by

austenizing, quenching, and then tempering toimprove their mechanical properties

These steels are often called machinery steelsApplications These are used for making camshafts,

connecting rods, gears, piston rods, etc.

HIGH CARBON STEELS These steels have 0.6 – 2.1 wt% C These are mainly tool steels They have very good hardness and wear

resistance values The tool and die steels are high-carbon alloys,

usually containing chromium, vanadium,tungsten, and molybdenum.

These alloying elements combine with carbonto form very hard and wear resistant carbidecompounds (e.g., Cr23C6, V4C3, and WC

These steels are utilized as cutting tools anddies for forming and shaping materials, as wellas in knives, razors, hacksaw blades, springs,and high-strength wire

HIGH ALLOY STEELS

Alloying elements are added to steel for many purposes:

i. To improve strengthii. To increase the hardenabilityiii. To improve wear and abrasion resistanceiv. To improve oxidation and corrosion

resistancev. To increase high temperature resistance vi. To increasing the toughness with retaining

strength

EFFECT OF ALLOYING ELEMENTS ON STEEL

Elements which tend to form carbides:Chromium, Tungsten, Titanium, Vanadium,Molybdenum, Manganese etc.

Elements which tend to graphitize carbon: theseelements are added to oppose the formation ofcarbides and they stabilize the carbon to occurin its free form as graphite. E.g.: Si, Co, Al, Ni etc.

Austenite stabilizers: these elements raise theperitectic point, increase the austenite range,and stabilize the austenite. E.g. Mn, Ni, Co, Cu

EFFECTS OF ELEMENTS ON STEELS Boron: Improves hardenability without the loss of (or

even with some improvement in) machinability andformability.

Calcium: Deoxidizes steels, improves toughness, andmay improve formability and machinability.

Carbon: improves hardenability, strength, hardness,and wear resistance; it reduces ductility, weldability,and toughness.

Cerium: controls the shape of inclusions and improvestoughness in high-strength low alloy steels; it deoxidizessteels.

Chromium: improves toughness, hardenability wearand corrosion resistance, and high-temperaturestrength; it increases the depth of the hardnesspenetration resulting from heat treatment by promotingcarburization.

Cobalt: improves strength and hardness at elevatedtemperatures.

EFFECTS OF ELEMENTS ON STEELS Copper: improves resistance to atmospheric corrosion

and, to a lesser extent, increases strength with little lossin ductility; it adversely affects the hot-workingcharacteristics and surface quality.

Lead: improves machinability; it causes liquid-metalembrittlement.

Magnesium: has the same effects as cerium. Manganese: improves hardenability, strength,

abrasion resistance, and machinability; it deoxidizesthe molten steel, reduce shot shortness, anddecreases weldability.

Molybdenum: improves hardenability, wearresistance, toughness, elevated-temperature strength,creep resistance, and hardness; it minimizes temperembrittlement.

EFFECTS OF ELEMENTS ON STEELS

Nickel: improves strength, toughness, and corrosionresistance; it improves hardenability.

Niobium (columbium): imparts fineness of grain sizeand improves strength and impact toughness; itlowers transition temperature and may decreasehardenability.

Phosphorus: improves strength, hardenability,corrosion resistance, and machinability; it severelyreduces ductility and toughness.

Selenium: improves machinability. Silicon: improves strength, hardness, corrosion

resistance, and electrical conductivity; it decreasesmagnetic-hysteresis loss, machinability, and coldformability.

Sulphur: Improves machinability when combined withmanganese; it lowers impact strength and ductility andimpairs surface quality and weldability. But decreasesthe high temperature strength.

Tantalum: has effects similar to those of niobium. Tellurium: improves machinability, formability, and

toughness. Titanium: improves hardenability; it deoxidizes steels. Tungsten: has the same effects as cobalt. Vanadium: improves strength, toughness, abrasion

resistance, and hardness at elevated temperatures; itinhibits grain growth during heat treatment.

Zirconium: has the same effects as cerium

IMPORTANT ALLOY STEELS

Tool steelsStainless steelsHSLA steelsMaraging steels

STAINLESS STEELS Excellent corrosion resistance Contain 12 to 30% Chromium

Cr oxidizes easily and forms a thin continuous layer of oxide that prevents further oxidation of the metal

Cr is a ferrite stabilizer

Austenite is restricted to a small region of the phase diagram

As this steels cannot be stained easily, it is called ss

Ferritic Stainless Steels are essentially Fe-Cr Alloys Ferrite phase (bcc structure) Inexpensive, high strength

An alloy steel containing a minimum of 12% chromium & additional nickel, manganese, and molybdenum alloy elements

Resistance to heat, oxidation & corrosion

Does not stain, corrode or rust as ordinary steel, but not stain-proof

Stainless Steel

FERROUS METALS

Austenitic Stainless Steels Nickel is an austenite stabilizer. The addition of both Cr and Ni results in the

austenite (g, fcc) phase being retained to roomtemperature

The austenite phase is very formable (fcc structure) Ni makes these alloys expensive

C-0.03 to 0.15% Mn-2 t0 10%Si-1 to 2% Cr-16 to 26%Ni- 3.5 to 22%

Martensitic Stainless Steels Have both Cr and C There is more Cr than in ferritic SS

since Cr tends to form Cr23C6, whichremoves available Cr for corrosionprotection

Can be heat treated to high strength

C-0.1 to 1.5% Mn-1 %Si-1 % Cr-12 to 25%Ni- 3.5 to 22%

STAINLESS STEELS

The reason for the name stainless is due tothe fact that in the presence of oxygen, thesteel develops a thin, hard, adherent film ofchromium. Even if the surface is scratched, the protective

film is rebuilt through passivation. For passivation to occur there needs to be a minimum

chromium content of 10% to 12% by weight.

FERROUS METALS

Stainless Steel

APPLICATION:

- Exterior Wall Finishes

- Interior Wall Finishes

- Railings

- Signage

- Doors & Windows

- Hardware

A group of low-carbon steels containing less than 2% alloys in a chemical composition specifically developed for increase strength, ductility, & resistance to corrosionMuch stronger & tougher than ordinary carbon steelCharacteristicsHigh yield strengthGood weldabilityCorrosion resistanceOnly limited ductility & virtually no hardability

HSLA (High-Strength Low-Alloy) Steel or (Micro alloyed steels)

FERROUS METALS

FERROUS METALS

HSLA Steel

0.20% cu is usually added to improve corrosion resistance

APPLICATION:

- Reinforcement for Pre-stressed Concrete

- High-strength Bolts

- Special Structural Steel

- Cables for Elevators

-Bridge towers,trains

-Pressure vessels etc

Maraging Steels Are Low Carbon, highly Alloyed Steels.These are very high strength materialsthat can be hardened to obtain tensile strengths up to 1900 Mpa.

MARAGING STEELS

compositionNi-18%Co-7%

Small amounts of other elements

CharacrertersticsVery high tensile and impact strength Tough with high strength Suitable for surface hardening by nitriding.Can be weld

CAST IRONS Fe-C alloys with 2-4%C 1-3% Si is added to improve cast ability Phase diagram shows graphite rather than Fe3C since C

may be present in the form of both graphite andcementite.

Temperatures and compositions are different from the Fe-Fe3C diagram

Features: Low melting temperature (1153ºC to 1400ºC) Low shrinkage Easily machinable Low impact resistance Low ductility

TYPES OF CAST IRON

CAST IRON

GRAY CAST RON

WHITE CAST IRON

NODULAR CAST IRON

MALLEABLE CAST IRON

TYPES OF CAST IRON

Also called spheroidallGraphite

OrDuctile cast

iron

C=2.5 -4% c

C=1.8to –

3.2 % c

GRAY CAST IRON Gray cast iron, named because its fracture has a gray

appearance

Produce by slow cooling.

Structure : Graphite in the form of flakes.

Properties :

> Advantages : Self-lubricate.

> Disadvantages : Negligible ductility, weak in tension.

Usage : Gear box, head stock, bearing bracket.

Figure 1. Graphite Flakes in Gray Cast iron

Figure 2. Photomicrograph of Gray Cast iron

GRAY CAST IRONGray Gray ironiron 2.5-4% Carbon graphite flakes weak & brittle under tension stronger under compression Excellent vibrational dampening wear resistant High fluidity Used for pressure vessels, clutch plates, base

structure for machines

WHITE CAST IRON Is called white cast iron because of the white crystalline

appearance of the fracture surface.

Produce by rapid cooling.

Structure : Iron carbide

Properties :

> Advantages : Very hard (difficult to machine), abrasion resistance.

> Disadvantages : Brittle.

o Usage : Extrusion dies, ball mills.

Figure 1. Photomicrograph of White Cast Iron

White iron<1wt% Si so harder but brittle

1.8-3.2% Carbon

more cementite

Fe3C-light phase, Pearlite dark phaseFracture surface – whitish surface

MALLEABLE CAST IRON Is called malleable cast iron because of latin words

‘malleus’ meaning ‘can be hammered’.

Produce by annealing white cast iron at 900˚C for 50hrs.

Structure : Graphite exists as clusters or rossetes.

Properties :

> Advantages : High ductility, strength and shock resistance.

> Disadvantages : NA

o Usage : Transmission gears, connecting rods.

Figure 1. Malleable Cast Iron

Malleable iron

heat treat at 800-900ºCgraphite in rosettesmore ductile

TypesFerritic malleable ironPearlitic malleable iron

NODULAR CAST IRON

Is called nodular cast iron because of graphite is in a nodular or spheroid form.

Produce when gray cast iron with small amounts of magnesium and cerium which nodulates the graphite.

Structure : Graphite in a nodular form.

Properties :

> Advantages : High strength and high ductility.

> Disadvantages : NA

Usage : Piston, crankshaft.

DUCTILE IRON (SG)

Ductile iron (SG) add Mg or Ce graphite in nodules not flakes matrix often pearlite - better

ductility

NONFERROUS ALLOYS

Non Ferrous Alloys

• Al Alloys

-lower r: 2.7g/cm3

-Cu, Mg, Si, Mn, Zn additions -solid sol. or precip.

strengthened (struct. aircraft parts & packaging)

• Mg Alloys-very low r: 1.7g/cm3

-ignites easily -aircraft, missiles

• Refractory metals-high melting T-Nb, Mo, W, Ta

• Noble metals-Ag, Au, Pt -oxid./corr. resistant

• Ti Alloys-lower r: 4.5g/cm3

vs 7.9 for steel-reactive at high T-space applic.

• Cu Alloys

Brass: Zn is subst. impurity(costume jewelry, coins, corrosion resistant)Bronze : Sn, Al, Si, Ni are subst. impurity (bushings, landing gear)Cu-Be: precip. hardened for strength

NON – FERROUS METAL.

Non-Ferrous Metals:Non-ferrous metals are metals that do not have any iron in them at all. This means that Non-ferrous metals are not attracted to a magnet and they also do not rust in the same way when exposed to moisture. Typical Non-ferrous metals include copper, aluminium (coke cans), tin and zinc.

Examples:1. Aluminium.2. Copper.3. Zinc.4. Tin.5. Lead.6. Silver.7. Gold.8. Magnesium.

Lead

TinZinc

NON – FERROUS METAL.

Metal Type.

Aluminium.It tends to be light in colour although it can be polished to a mirror like appearance. It is very light in weight.

Metal Uses.

Used for saucepans, cooking foil, window frames, ladders, expensive bicycles.

Melting Point.

660°C

NON – FERROUS METAL.

Metal Type.

Copper.It is a ductile and malleable metal. It is often red / brown in colour. It is a very good conductor of heat and electricity.

Metal Uses.

Used for plumbing, electric components, cookware and roof coverings.

Melting Point.

1084°C

IMPORTANT COPPER ALLOYS ARE

Brasses (copper-zinc alloys)Bronzes (copper- tin alloys)Gun-metals( copper-tin –zinc alloys)Cupro nickels ( alloys)

Lead mat add to improve castability

And machineability

NON – FERROUS METAL.

Metal Type.

Zinc.It is very resistant to corrosion from moisture. However zinc is a very weak metal and is used mainly for coating steel.

Metal Uses.

Used as a coating on screws, steel buckets etc It is also used to galvanize steel.

Melting Point.

419°C

NON – FERROUS METAL.

Metal Type.

Tin.It is a very ductile and very malleable metal. It is resistant to corrosion from moisture. It is bright silver in appearance. Tinplate is steel with a tin coating.

Metal Uses.

Used as a coating on food cans, beer cans. Used as whistles, tin foil and soldering.

Melting Point.

231°C

NON – FERROUS METAL.

Metal Type.

Lead.It is a soft, malleable metal. It is also counted as one of the heavy metals. Lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air.

Metal Uses.

Used for roof flashing. Also used for batteries and for X-ray protection. Lead is used for its weight in many ways.

Melting Point.

327°C

NON – FERROUS METAL.

Metal Type.

Silver.A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. The metal occurs naturally in its pure, free form.

Metal Uses.

Used for jewelry and high quality cutlery. Also used for currency coins and sports trophies. Used in mirrors as a reflective metal.

Melting Point.

961°C

NON – FERROUS METAL.

Metal Type.

Gold.Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Gold resists attacks by individual acids It won't tarnish, discolor, crumble, or be affected by most solvents.

Metal Uses.

Used mainly for jewelry. Also used in computers as a conductor. Used for its reflective powers to protect satellites.

Melting Point.

1337°C

NON – FERROUS METAL.

Metal Type.

Magnesium.Magnesium is a fairly strong, silvery-white, light-weight metal (one third lighter than aluminum) that slightly tarnishes when exposed to air. In a powder, this metal heats and ignites when exposed to moisture and burns with a white flame.

Metal Uses.

Magnesium is used in pyrotechnic (i.e. fireworks). It is alloyed with other metals to make them lighter and more easily welded.

Melting Point.

648°C

NON – FERROUS METAL ALLOYS.

Non-Ferrous Metal Alloys:Non-ferrous metal alloys are metals that are a mixture of two or more metals. The main ones in everyday use are,

Brass.Bronze.Solder.

Heating metals in a furnace to form an alloy.

NON – FERROUS METAL ALLOYS.

Metal Type.

Brass.Brass is a mixture of copper and zinc. Copper is the main component, and brass is usually classified as a copper alloy. The color of brass varies from a dark reddish brown to a light silvery yellow. Brass is stronger and harder than copper, but not as strong or hard as steel. It is easy to form into various shapes, a good conductor of heat, and generally resistant to corrosion from salt water.

Metal Uses.

Brass is used to make water fittings, screws, radiators, musical instruments, and cartridge casings for firearms.

Melting Point.

940°C

NON – FERROUS METAL ALLOYS.

Metal Type.

Bronze.Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is a hard and brittle metal. It has a very high resistance to corrosion.

Metal Uses.

Used for ship propellers and underwater fittings. Also used for statues and medals.

Melting Point.

950°C

REVISION WORK/METALS.