Assignment Civ 428

8/8/2019 Assignment Civ 428

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Table of Contents

Table of Contents ............................................................................................................................. 1

INTRODUCTION ...........................................................................................................................3

MANUFACTURE PROCESS OF STRUCTURAL STEEL .......................................................... 5Making steel .................................................................................................................................5

The Blast Furnace ........................................................................................................................ 6

Hot Rolled Steel Hot Rolling ....................................................................................................8

EFFECTS OF CHEMISTRY ON STEEL PROPERTIES ............................................................ 13

Carbon ........................................................................................................................................13

Aluminum .................................................................................................................................. 13

Boron ......................................................................................................................................... 14

Chromium .................................................................................................................................. 14

Columbium ................................................................................................................................14

Copper ........................................................................................................................................14

Hydrogen ................................................................................................................................... 15

Manganese .................................................................................................................................15

Molybdenum ..............................................................................................................................15

Nickel .........................................................................................................................................15

Nitrogen .....................................................................................................................................15

Oxygen .......................................................................................................................................15

Phosphorus .................................................................................................................................16

Silicon ........................................................................................................................................ 16

Sulfur ......................................................................................................................................... 16

Titanium .....................................................................................................................................16

Tungsten ....................................................................................................................................16


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Vanadium ...................................................................................................................................16

Maraging steels .......................................................................................................................... 18

THE TYPES OF PROTECTION METHODS FOR STRUCTURAL STEEL .............................19

Fire Protection for Structural Steel ............................................................................................ 19

Cementitious products ...................................................................................................................19

Cementitious products ..........................................................................................................19

Board and casing systems ..............................................................................................................19

Board and casing systems .....................................................................................................19Protection against Corrosion ......................................................................................................20

Coatings ......................................................................................................................................... 20Coatings ................................................................................................................................20

Structural Fasteners ........................................................................................................................21

ASTM, SAE AND ISO GRADE MARKINGS AND MECHANICAL PROPERTIES FOR

STEEL FASTENERS ................................................................................................................23

FASTENER IDENTIFICATION MARKING ..........................................................................27

LIMITATIONS ON USE OF FASTENERS AND WELDS .................................................... 28

Connections and Fasteners for Cold Form Steel .......................................................................29

Usual mechanical fasteners for common applications ...............................................................30

Reference ....................................................................................................................................... 39


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INTRODUCTION

According to the ironcarbon phase diagram [13], all binary FeC alloys containing less than

about 2.11 wt% carbon are classified as steels, and all those containing higher carbon content

are termed cast iron. When alloying elements are added to obtain the desired properties, the

carbon content used to distinguish steels from cast iron would vary from 2.11 wt%.

Steels are the most complex and widely used engineering materials because of (1) the abundance

of iron in the Earths crust, (2) the high melting temperature of iron (15348C), (3) a range of

mechanical properties, such as moderate (200300 MPa) yield strength with excellent ductility to

in excess of 1400 MPa yield stress with fracture toughness up to 100 MPam_2, and (4)

associated microstructures produced by solid-state phase transformations by varying the cooling

rate from the austenitic condition.

Steel has been part of some of the greatest achievements in history: Steel is stronger than iron

and considerably more versatile. From the thinnest surgical needles to immense ships, steel is the

material of choice. It was the "iron horse" and steel rails that helped carve a nation out of the

frontier. Steel is the backbone of bridges, the skeleton of skyscrapers, and the framework for

automobiles. And at the dawn of the 21st century, it's still revolutionizing the way we live. It is

the high-strength, lighter-than-plastic frames for eyeglasses; it's the stronger, more durable frame

in housing; it's the high-tech alloy used in the Space Shuttle's solid fuel rocket and motor cases.

(American Iron and Steel Institute 2002) Yes steel today is in just about everything we use today.

Steel too has changed over the years.

Iron has been a vital material in technology for well over three thousand years. But until the

Industrial Revolution, its mining, smelting, and working were largely done by individuals and

small groups. Known since ancient times, steel is made by alloying iron with carbon to produce

a harder, stronger metal that will take a much keener edge. But steel was very expensive to

manufacture by the primitive methods then available, and its use was largely confined to high-

value specialty products such as swords and precision instruments. (Garraty 1991) Steel

making (in the 18th century) was a laborious and time-consuming process. Flat bars of iron were

laid in a furnace chest, side by side on a bed of charcoal. The bars were the covered with


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charcoal, another layer of iron bars was placed on top of that and the process was repeated until

the chest was full. It was then placed in the furnace, covered with a layer of sand and cooked red-

hot for a week. During this time the carbon from the charcoal was absorbed into the outer layers

of the iron, the carbonized areas forming blisters on the surface of the bars. When the chest was

removed and had cooled down, these blisters were hammered off, and the pieces reheated and

hammered together. The resultant blister steel was brittle and difficult to work. (Burke 1996)

The Blast furnace technique came some time after this. The blast furnace, which consisted of

blowing steam or air through molten iron, had become widely used by the ninetieth century.

Along came a man by the name Henry Bessemer who would invent a new way to produce steel

using the blast method called the Bessemer process, the most important technique for making

steel in the nineteenth century. (Misa 1995) He first came across this while melting gun metal

down. Bessemer built a crucible with a blow pipe extended into its center. Into the crucible he

poured about 10 pounds of unrefined pig iron and then placed the apparatus into a hot furnace;

after 30 minutes of blowing air into the metal, he found the crude iron had become malleable

iron. This experiment proved air could decarburize pig iron, turning it into a useful product, yet

the furnace surrounding the crucible still consumed copious amounts of fuel. Bessemer's real

insight was to get rid of the furnace entirely. For this he built a four-foot tall, open-mouthed

cylinder with openings, or tuyres, to blow air into the metal from the bottom. (Misa 1995)

Acceptance of the process was slow at first, so that by 1870 the annual output of Bessemer steel

in the United States was a mere 42,000 tons. Production grew rapidly thereafter, rising to 1.2million tons in 1880. The principal application of Bessemer steel in the 19th century was for the

manufacture of railroad rails, which proved far more durable than iron rails. By the 1890s

virtually no more iron rails were being produced.


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MANUFACTURE PROCESS OF STRUCTURAL STEEL

Making steel

Iron and steel are made from iron ore. Iron ores are rocks and minerals from which metallic iron

can be economically extracted. The ores are usually rich in iron oxides and vary in colour from

dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of

magnetite (Fe3O4), hematite (Fe2O3), goethite, limonite or siderite. Hematite is also known as

"natural ore". The rock and minerals containing iron ore is dug from the earth and put into a blast

furnace. Charcoal, made from coal and limestone are put into the furnace with the rock and air is

blasted into it. It gets very hot! The iron ore melts and the liquid iron runs out and cools. It is

now called 'pig iron'.Pig iron is used to make wrought iron for garden furniture, some tools and

horseshoes but most importantly used to make steel.
http://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Mineralhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Iron_oxidehttp://en.wikipedia.org/wiki/Magnetitehttp://en.wikipedia.org/wiki/Haematitehttp://en.wikipedia.org/wiki/Goethitehttp://en.wikipedia.org/wiki/Limonitehttp://en.wikipedia.org/wiki/Sideritehttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Mineralhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Iron_oxidehttp://en.wikipedia.org/wiki/Magnetitehttp://en.wikipedia.org/wiki/Haematitehttp://en.wikipedia.org/wiki/Goethitehttp://en.wikipedia.org/wiki/Limonitehttp://en.wikipedia.org/wiki/Siderite


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The Blast Furnace


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Steel is made from pig iron. Steel is iron that has most of the impurities removed. Steel also has

a consistent concentration of carbon throughout (0.5 to 1.5 percent). Impurities like silica,

phosphorous and sulfur weaken steel tremendously, so they must be eliminated. The advantage

of steel over iron is greatly improved strength.

The open-hearth furnace is one way to create steel from pig iron. The pig iron, limestone and

iron ore go into an open-hearth furnace. It is heated to about 1,600 degrees F (871 degrees C).

The limestone and ore form a slag that floats on the surface. Impurities, including carbon, are

oxidized and float out of the iron into the slag. When the carbon content is right, you have carbon

steel.

Another way to create steel from pig iron is the Bessemer process, which involves the oxidation

of the impurities in the pig iron by blowing air through the molten iron in a Bessemer converter.

The heat of oxidation raises the temperature and keeps the iron molten. As the air passes through

the molten pig iron, impurities unite with the oxygen to form oxides. Carbon monoxide burns off

and the other impurities form slag.

However, most modern steel plants use what's called a basic oxygen furnace to create steel. The

advantage is speed, as the process is roughly 10 times faster than the open-hearth furnace. In

these furnaces, high-purity oxygen blows through the molten pig iron, lowering carbon, silicon,

manganese and phosphorous levels. The addition of chemical cleaning agents called fluxes helpto reduce the sulfur and phosphorous levels.

At this stage other elements can be added to achieve different properties for example manganese

to increase strength and resistance to wear, or molybdenum to improve strength and resistance to

heat creating whats known as an alloy steel. To make an alloy steel, the basic steel is put into a

huge container called a ladle, and the other elements are added. For example, the addition of 10

to 30 percent chromium creates stainless steel, which is very resistant to rust.


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The molten steel is cast into basic shapes of different sizes and cooled. Next up is a process

called rolling. The steel is passed between two rollers that flatten and lengthen it, much as pie

dough is shaped by a rolling pin. If the steel is "hot rolled," heated to a temperature of about

1200 degrees Celsius, its much more able to withstand stress without cracking or breaking. If

the steel is "cold rolled," rolled at room temperature, it makes the steel thinner and smoother,

and gives it a shiny finish. Sometimes both processes are used.

Rolling can produce many final shapes, as well. The most common are flat sheets and the

narrower flat strips, but this process can also turn out structural beams and a variety of bars. Wire

needs more work: Its made by drawing a round bar through a series of smaller and smaller holes

called dies. For some intended uses, theres additional processing, but basically this is it. The

finished steel can be sent off to a customer who will build a bridge, manufacture cookware, or

make millions of paper clipswhatever the particular steel was designed to do best.

Hot Rolled Steel Hot Rolling

Most structural sections used by architects and engineers are formed by hot-rolling in a

range of standard sizes.

White hot slabs of cast steel are sent into the rolling mill and are passed through sets of rollers

which gradually change the profile into the familiar 'I' and 'H' sections. These are produced in a

wide range of section sizes. These are known as universal beams and columns, identified by


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serial size and mass per unit length. Each serial size corresponds to a different set of roller sizes.

Changes in mass per unit length are achieved by increasing the thickness of the flanges during

rolling.

Hot Rolled Steel Shapes

During the production of special steel profiles by hot rolling the input billet or slab is formed into

lengths up to 70 m using two oppositely rotating cylindrical rolls. The hot rolled steel shapes of

this forming technique are used in a multitude of industrial applications. Hot rolled special pro-

files offer innovative solutions whether it be for automotive, materials handling, railroad or

thicker flange and web thickness structural steel shapes use. Finished hot rolled steel shapes are

roller straightened and sheared into production lengths or sawn into fixed lengths according to

customer wishes.

Targeted strengthening of highly stressed areas of component parts

Best mechanical properties through uninterrupted grain orientation

Best shape properties and fitting accuracy by maintenance of the tightest tolerances

Hot extruding Extruded Steel Shapes Steel Extrusions

Extruded Stainless Steel

Stainless Steel Extrusions

During hot extrusion a round steel billet is pre-heated and, after leaving the furnace, is pushed

through a forming die into a profile bar using a ram with an extrusion force of 2,200 ton.Hot

extrusion offers substantial advantages in comparison to hot rolling forging or machining. Hot

extrusion can be used to make complex profile shapes even using metals which are difficult to

form. In addition, small lot sizes can be produced economically. Hot extruded profiles offer the

benefit of:

Different material thicknesses within one profile cross-section

The possibility to use in highly sensitive areas, where the special profiles must withstand

specific demands of temperature, pressure, aggressive media or hygienic requirements

Seamless structure of solid and hollow section


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Cold-formed members are normally manufactured by one of two processes. These are:

(a) Roll forming;

(b) Folding

(c) press braking.

Roll forming consists of feeding a continuous steel strip through a series of opposing rolls to

progressively deform the steel plastically to form the desired shape. Each pair of rolls produces a

fixed amount of deformation in a sequence of type shown in Figure 5a. In this example, a section

is formed. Each pair of opposing rolls is called a stage as shown in Figure 5. In general, the more

complex the cross-sectional shape, the greater the number of stages required. In the case of cold-

formed rectangular hollow sections, the rolls initially form the section into a circular section and a

weld is applied between the opposing edges of the strip before final rolling (called sizing) into a

square or rectangular shape.

Figures 6, a and b, shows two industrial roll forming lines for long products profiles and sheeting,

respectively.

Fig. 5: Stages in roll forming a simple section (Rhodes, 1992)


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Fig. 6: Industrial roll forming lines

A significant limitation of roll forming is the time taken to change rolls for a different size sections.

Consequently, adjustable rolls are often used which allows a rapid change to a different section width

or depth.

Folding is the simplest process, in which specimens of short lengths and of simple geometry is

produced from a sheet of material by folding a series of bends (see Figure 7). This process has verylimited application.

Fig. 8: Forming steps in press braking process

Fig. 7: Forming of folding


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Press-braking is more widely used, and a greater variety of cross-sectional forms can be produced by

this process. Here a section is formed from a length of strip by pressing the strip between shaped dies

to form the profile shape (see Figure 8). Usually each bend is formed separately. The set up of a

typical brake press is illustrated in Figure 8. This process also has limitations on the profiled

geometry which can be formed, and, often more importantly, on the lengths of sections which can be

produced. Press-braking is normally restricted to sections of length less than 5 m although press

brakes capable of production 8 m long members are in use in industry. Roll forming is usually used

to produce sections where very large quantities of a given shape are required. The initial tooling costs

are high but the subsequent labour content is low. Brake pressing is normally used for low volume

production where a variety of shapes are required and the roll forming tooling costs cannot be

justified.


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EFFECTS OF CHEMISTRY ON STEEL PROPERTIES

Chemical composition determines many characteristics of steels important in construction

applications. Some of the chemicals present in commercial steels are a consequence of the

steelmaking process. Other chemicals may be added deliberately by the producers to achieve

specific objectives. Specifications therefore usually require producers to report the chemical

composition of the steels.

During the pouring of a heat of steel, producers take samples of the molten steel for chemical

analysis. These heat analyses are usually supplemented by product analyses taken from drillings

or millings of blooms, billets, or finished products. ASTM specifications contain maximum and

minimum limits on chemicals reported in the heat and product analyses, which may differ

slightly.

Principal effects of the elements more commonly found in carbon and low-alloy steels are

discussed below. Bear in mind, however, that the effects of two or more of these chemicals when

used in combination may differ from those when each alone is present. Note also that variations

in chemical composition to obtain specific combinations of properties in a steel usually increase

cost, because it becomes more expensive to make, roll, and fabricate.

Carbon

Carbon is the principal strengthening element in carbon and low-alloy steels. In general, each

0.01% increase in carbon content increases the yield point about 0.5 ksi. This, however, is

accompanied by increase in hardness and reduction in ductility, notch toughness, and

weldability, raising of the transition temperatures, and greater susceptibility to aging. Hence

limits on carbon content of structural steels are desirable. Generally, the maximum permitted in

structural steels is 0.30% or less, depending on the other chemicals present and the weldability

and notch toughness desired.

AluminumAluminum, when added to silicon-killed steel, lowers the transition temperature and increases

notch toughness. If sufficient aluminum is used, up to about 0.20%, it reduces the transition

temperature even when silicon is not present. However, the larger additions of aluminum make it

difficult to obtain desired finishes on rolled plate. Drastic deoxidation of molten steels with


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HydrogenHydrogen, which may be absorbed during steelmaking, embrittles steels. Ductility will improve

with aging at room temperature as the hydrogen diffuses out of the steel, faster from thin sections

than from thick. When hydrogen content exceeds 0.0005%, flaking, internal cracks or bursts,

may occur when the steel cools after rolling, especially in thick sections. In carbon steels, flakingmay be prevented by slow cooling after rolling, to permit the hydrogen to diffuse out of the steel.

Manganese

Manganese increases strength, hardenability, fatigue limit, notch toughness, and corrosion

resistance. It lowers the ductility and fracture transition temperatures. It hinders aging. Also, it

counteracts hot shortness due to sulfur. For this last purpose, the manganese content should be

three to eight times the sulfur content, depending on the type of steel. However, manganese

reduces weldability.

Molybdenum

Molybdenum increases yield strength, hardenability, abrasion resistance, and corrosion

-resistance. It also improves weldability. However, it has an adverse effect on toughness and

transition temperature. With small amounts of molybdenum, low-alloy steels have higher creep

strength than carbon steels and are used where higher strength is needed for elevatedtemperature

service.

NickelNickel increases strength, hardenability, notch toughness, and corrosion resistance. It is an

important constituent of stainless steels. It lowers the ductility and fracture transition

temperatures, and it reduces weldability.

Nitrogen

Nitrogen increases strength, but it may cause aging. It also raises the ductility and fracturetransition temperatures.

OxygenOxygen, like nitrogen, may be a cause of aging. Also, oxygen decreases ductility and notch

toughness.


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PhosphorusPhosphorus increases strength, fatigue limit, and hardenability, but it decreases ductility and

weldability and raises the ductility transition temperature. Additions of aluminum, however,

improve the notch toughness of phosphorus-bearing steels. Phosphorus improves the corrosion

resistance of steel and works very effectively together with small amounts of copper toward thisresult.

Silicon

Silicon increases strength, notch toughness, and hardenability. It lowers the ductility transition

temperature, but it also reduces weldability. Silicon often is used as a deoxidizer in steelmaking.

Sulfur

Sulfur, which enters during the steelmaking process, can cause hot shortness. This results from

iron sulfide inclusions, which soften and may rupture when heated. Also, the inclusions may lead

to brittle failure by providing stress raisers from which fractures can initiate. And high sulfur

contents may cause porosity and hot cracking in welding unless special precautions are taken.

Addition of manganese, however, can counteract hot shortness. It forms manganese sulfide,

which is more refractory than iron sulfide. Nevertheless, it usually is desirable to keep sulfur

content below 0.05%

TitaniumTitanium increases creep and rupture strength and abrasion resistance. It plays an important role

in preventing aging. It sometimes is used as a deoxidizer in steelmaking (see Art. 1.24) and

grain-growth inhibitor.

Tungsten

Tungsten increases creep and rupture strength, hardenability and abrasion resistance. It is used

in steels for elevated-temperature service.

VanadiumVanadium, in amounts up to about 0.12%, increases rupture and creep strength without

impairing weldability or notch toughness. It also increases hardenability and abrasion resistance.


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Vanadium sometimes is used as a deoxidizer in steelmaking (see Art. 1.24) and grain growth

inhibitor.

In practice, carbon content is limited so as not to impair ductility, notch toughness, and

weldability. To obtain high strength, therefore, resort is had to other strengthening agents that

improve these desirable properties or at least do not impair them as much as carbon. Often, the

better these properties are required to be at high strengths, the more costly the steels are likely to

be.

Attempts have been made to relate chemical composition to weldability by expressing the

relative influence of chemical content in terms ofcarbon equivalent. One widely used formula,

which is a supplementary requirement in ASTM A6 for structural steels, is

where C _ carbon content, %

Mn _ manganese content, %

Cr _ chromium content, %

Mo _ molybdenum, %V _ vanadium, %

Ni _ nickel content, %

Cu _ copper, %

Carbon equivalent is related to the maximum rate at which a weld and adjacent plate may be

cooled after welding, without underbead cracking occurring. The higher the carbon equivalent,

the lower will be the allowable cooling rate. Also, use of low-hydrogen welding electrodes and

preheating becomes more important with increasing carbon equivalent. (Structural

Welding CodeSteel, American Welding Society, Miami, Fla.)

Though carbon provides high strength in steels economically, it is not a necessary ingredient.

Very high strength steels are available that contain so little carbon that they are considered

carbon-free.


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Maraging steelsMaraging steels, carbon-free iron-nickel martensites, develop yield strengths from 150 to 300

ksi, depending on alloying composition. As pointed out in Art. 1.20, iron-carbon martensite is

hard and brittle after quenching and becomes softer and more ductile when tempered. In contrast,

maraging steels are relatively soft and ductile initially but become hard, strong, and tough whenaged. They are fabricated while ductile and later strengthened by an aging treatment. These steels

have high resistance to corrosion, including stresscorrosion cracking.

(W. T. Lankford, Jr., ed., The Making, Shaping and Treating of Steel, Association of Iron

and Steel Engineers, Pittsburgh, Pa.)


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THE TYPES OF PROTECTION METHODS FOR

STRUCTURAL STEEL

Fire Protection for Structural SteelThere are three generic types of fire protection for structural steel:

Cementitious products

Board and casing systems

Intumescent coatings

Cementitious products

Cementitious products based on gypsum or Portland cement binders are normally applied by low

pressure spray techniques to the profile of the steel section to be protected. These materials

contain low density aggregates and rheological aids to help the application characteristics. Fire

protection is provided to the steel by these materials in two ways, the first being the cooling

effect as the trapped moisture (physically and chemically bound) evaporates as the temperature

of the surrounding fire increases. Once all the moisture has turned to steam the product then

behaves as a thermal insulation material. Low density mineral and synthetic aggregates are used

in these products since they are efficient in allowing the steam to escape, while denser materialsmight impede its progress and cause the product to spall.

Board and casing systems

Board and casing systems use materials such as ceramic wool, mineral wool, fire resistant

plasterboard, calcium silicate and vermiculite to provide fire protection to steel. These products

provide fire protection in much the same way as the cementitious products and are dry fixed

around the steel using clip, pin, noggin and screw systems.

Intumescent coatings

Intumescent coatings derive their name from the Latin verb tumescere, which means to begin to

swell. In a fire situation, these thin film products swell up to form a char which protects the steel,

thanks to its insulating properties. Using various types of industrial coating equipment, these

materials are applied as a thin film and are often available with a range of topcoats in different


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colours so that the designer can achieve his or her aesthetic needs as well as those of fire

protection on visible steel. Intumescent coatings are particularly effective for steel that requires

up to 90 minutes protection.

Protection against Corrosion

Coatings

Structural components are typically coated to provide a first line of defense against corrosion.

Commonly used coatings include conversion, hot melt wax, electrocoat, metallic, organic,

autodeposition and powder.

Phosphate conversion coatings are employed to enhance paint adhesion, thereby indirectly

enhancing corrosion resistance.Hot melt wax coatings are used extensively on underbody structural components to provide

corrosion protection, and are usually applied through a dipping process.

Electrocoating orE-coating is a process in which electrically charged particles are deposited

out of a water suspension to coat a conductive part. The process requires a coating tank in which

the part is completely immersed. E-coat is widely used to protect underbody structural

components from corrosion. Metallic coatings such as zinc, zinc-iron and aluminum are applied

to steel components to inhibit corrosion, using the electroplating, mechanical plating, electroless

or hot dipping process.

Many underbody structural components are manufactured from sheet steel with a metallic

coating. The steel mills supply hot or cold rolled sheet in coil form with metallic coatings applied

by either electroplating or hot dipping. Organic, autodeposition and powder coatings are also

available to protect underbody structural components.

An organic coating such as paint is a cost effective corrosion protection method. It prevents, or

retards, the transfer of electrochemical charge from the corrosive solution to the metal beneath

the coating.

Autodeposition is a waterborne process that relies on chemical reactions to achieve deposition.

A mildly acidic latex bath attacks a steel part immersed in it. Iron ions are released and react

with the latex in solution causing a deposition or coating on the surface of the steel part.

A powder coating is achieved by applying a dry powder to a part. The part is then heated, fusing

the powder into a smooth, continuous film.


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Structural Fasteners

There is currently a myriad of structural fasteners available, each developed for specific

applications. For structural applications where only snug-tightened bolted joints are required,

low-strength ASTM A307 bolts are permitted, but typically considered only for secondary

members or low-load applications. High-strength bolts such as ASTM A325 and A490 are the

more common choice. There are four pretensioning methods of bolt installation sanctioned by

the RCSC specification turn-of-the-nut, calibrated wrench, twist-off-type tension-control bolt,

and direct-tension-indicator. For pretensioned and slip-critical bolted joints, one will need to

considerASTM A325 and A490 high strength bolts, or alternatively, F1852 and F2280 tension-

control bolt assemblies. IfASTM A325 orA490 high-strength bolts are used in pretensioned and

slip critical joints, one can choose turn-of-the nut or calibrated wrench, or decide to use ASTM

F959 direct-tension-indicator washers to determine that the minimum level of installation

pretension has been provided. In all cases, the pre-installation verification requirements of the

RCSC specification must be followed. The newest addition to the structural bolting family is

ASTM F2280, which is a tension-control bolt with a material strength equivalent to an ASTM

A490 high-strength bolt. One should never confuse structural bolts with anchor rods, or

improperly use one when the other is required. AISC changed the term anchor bolt to anchor

rod about 17 years ago to highlight the differences between bolts used in steel-to-steel

connections and those used in anchoring steel-to-concrete. The design and installation

parameters are quite different for each. Structural bolt lengths are usually available in lengths of

8 in. or less, which is typically insufficient for proper embedment development length as an

anchor rod. When thinking about column anchorage, one should remember that ASTM F1554

Grade 36 is the preferred material specification for anchor rods. It contains the same chemical

and structural properties as ASTM A36 rod, but includes two important aspects: color coding

and inclusion in the ASTM F1554 anchor rod standard. ASTM F1554 is an umbrella anchor

rod standard, as it establishes the process, threading, coatings, dimensions, and tolerances for

anchor rods. No other ASTM Standard for rod material establishes these important requirements.

ASTM F1554 includes a Grade 55, which can be ordered to Supplementary Requirement S1,

which ensures weldability. There is also a Grade 105 for high-strength applications, which is a

heat-treated material; hence, it cannot be ordered to Supplementary Requirement S1 to ensure

weldability. It should be noted that threaded rods are typically used for tension-only bracing or


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ASTM, SAE AND ISO GRADE MARKINGS ANDMECHANICAL PROPERTIES FOR STEEL FASTENERS

IdentificationGrade Mark

SpecificationFastener

DescriptionMaterial

NominalSize

Range(in.)

Mechanical Properties

Proof

Load(psi)

Yield

StrengthMin (psi)

Tensile

StrengthMin (psi)

NoGradeMark

SAE J429Grade 1

Bolts,Screws,

Studs

Low or MediumCarbon Steel

1/4 thru 1-1/2

33,000 36,000

60,000ASTM A307Grades A&B

Low Carbon Steel 1/4 thru 4 -- --

SAE J429Grade 2

Low or MediumCarbon Steel

1/4 thru3/4 Over3/4 to 1-

1/2

55,00033,000

57,00036,000

74,00060,000

NoGradeMark

SAE J429Grade 4

StudsMedium Carbon

Cold Drawn Steel1/4 thru 1-

1/2-- 100,000 115,000

B5

ASTM A193Grade B5

AISI 501

1/4 Thru 4 --

80,000 100,000

B6

ASTM A193Grade B6

AISI 410 85,000 110,000

B7

ASTM A193Grade B7

AISI 4140, 4142,OR 4105

1/4 thru 2-1/2

Over 2-1/2thru 4Over 4thru 7

------

105,00095,00075,000

125,000115,000100,000

B16

ASTM A193Grade B16

CrMoVa Alloy Steel105,00095,00085,000

125,000115,000100,000

B8

ASTM A193Grade B8

AISI 304

1/4 andlarger

-- 30,000 75,000

B8C

ASTM A193Grade B8C

AISI 347

B8M

ASTM A193Grade B8M

AISI 316


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B8T

ASTM A193Grade B8T

Bolts,Screws,

Studs for High-Temperature

Service

AISI 3211/4 andlarger

-- 30,000 75,000

B8

ASTM A193Grade B8

AISI 304Strain Hardened

1/4 thr 3/4Over 3/4

thru 1Over 1

thru 1-1/4Over 1-1/4thru 1-1/2

--------

100,000

80,00065,00050,000

125,000

115,000105,000100,000

B8C

ASTM A193Grade B8C


B8M

ASTM A193Grade B8M


95,00080,00065,00050,000

110,000100,00095,00090,000

B8T

ASTM A193Grade B8T


100,00080,00065,000

50,000

125,000115,000105,000

100,000

L7

ASTM A320Grade L7

Bolts,Screws,

Studs for Low-Temperature

Service

AISI 4140,4142 or 4145

1/4 thru 2-1/2

-- 105,000 125,000L7A

ASTM A320Grade L7A

AISI 4037

L7B

ASTM A320Grade L7B

AISI 4137

L7C

ASTM A320Grade LC7

AISI 8740

L43

ASTM A320Grade L43

AISI 4340 1/4 thru 4 -- 105,000 125,000

B8

ASTM A320Grade B8

Bolts,Screws,

Studs for Low-Temperature

Service

AISI 304

1/4 andlarger

-- 30,000 75,000

B8C

ASTM A320Grade B8C

AISI 347

B8T

ASTM A320Grade B8T

AISI 321


25/39

B8F

ASTM A320Grade B8F

AISI 303or 303Se

B8M

ASTM A320Grade B8M

AISI 316

B8

ASTM A320Grade B8

AISI 304

1/4 thru3/4

Over 3/4thru 1Over 1

thru 1-1/4Over 1-1/4thru 1-1/2

--------

100,00080,00065,0050,00

100,00080,00065,0050,00

B8C

ASTM A320Grade B8C

AISI 347

B8F

ASTM A320Grade B8F

AISI 303or 303Se

B8M

ASTM A320Grade B8M

AISI 316

B8T

ASTM A320Grade B8T

AISI 321

SAE J429Grade 5

Bolts,

Screws,Studs

Medium Carbon

Steel, Quenchedand Tempered

1/4 thru 1Over 1 to

1-1/2

85,00074,000

92,00081,000

120,000105,000

ASTM A449

1/4 thru 1Over 1 to1-1/2

Over 1-1/2thru 3

85,00074,00055,000

92,00081,00058,000

120,000105,00090,000

SAE J429Grade 5.1

Sems

Low or MediumCarbon Steel,Quenched and

Tempered

No. 6thru 3/8

85,000 -- 120,000

SAE J429Grade 5.2

Bolts,Screws,Studs

Low CarbonMartensitic Steel,Quenched and

Tempered

1/4 thru 1 85,000 92,000 120,000

A325

ASTM A325Type 1

High StrengthStructural Bolts

Medium CarbonSteel, Quenchedand Tempered

1/2 thru 11-1/8 thru

1-1/2

85,00074,000

92,00081,000

120,000105,000

A325

ASTM A325Type 2

Low CarbonMartensitic Steel,Quenched and

Tempered

1/2 thru 1 85,000 92,000 120,000


26/39

A325

ASTM A325Type 3

AtmosphericCorrosion

Resisting Steel,Quenched and

Tempered

1/2 thru 11-1/8 thru

1-1/2

85,00074,000

92,00081,000

120,000105,000

BB

ASTM A354

Grade BBBolts,Studs

Alloy Steel,Quenched and

Tempered

1/4 thru 2-1/2

2-3/4 thru4

80,000

75,000

83,000

78,000

105,000

100,000

BC

ASTM A354Grade BC

105,00095,000

109,00099,000

125,000115,000

SAE J429Grade 7

Bolts,Screws,

Medium CarbonAlloy Steel,

Quenched andTempered 4

1/4 thru 1-1/2

105,000 115,000 133,000

SAE J429

Grade 8 Bolts,Screws,Studs

Medium CarbonAlloy Steel,

Quenched andTempered 1/4 thru 1-1/2

120,000 130,000 150,000

ASTM A354Grade BD


Tempered 4

No GradeMark

SAE J429Grade 8.1

Studs

Medium CarbonAlloy or SAE 1041Modified Elevated

TemperatureDrawn Steel

1/4 thru 1-1/2

120,000 130,000 150,000

A490

ASTM A490High Strength

Structural Bolts


Tempered

1/2 thru 1-

1/2

120,000 130,000

150,000min

170,000max

No GradeMark

ISO R898Class 4.6

Bolts,Screws,Studs


All Sizesthru 1-1/2

33,000 36,000 60,000

No GradeMark

ISO R898Class 5.8

55,000 57,000 74,000

8.8

or

88

ISO R898Class 8.8 Alloy Steel,Quenched andTempered

85,000 92,000 120,000


27/39

10.9

or

109

ISO R898Class 10.9

120,000 130,000 150,000

FASTENER IDENTIFICATION MARKING

GradeIdentification

MarkingSpecification Material

Nominal SizeIn.

ProofLoad

Stressksi

HardnessRockwell See

NoteMin Max

No Mark

ASTM A563 - Grade 0 Carbon Steel 1/4 thru 1-1/2 69 B55 C32 3,4

ASTM A563 - Grade A Carbon Steel 1/4 thru 1-1/2 90 B68 C32 3,4

ASTM A563 - Grade B Carbon Steel

1/4 thru 1 120

B69 C32 3,4over 1 thru 1-1/2

105

ASTM A563 - Grade C

Carbon SteelMay be

Quenchedand Tampered

1/4 thru 4 144 B78 C38 5

ASTM A563 - Grade C3


Resistant SteelMay be


1/4 thru 4 144 B78 C38 5,9

ASTM A563 - Grade D

Carbon SteelMay be


1/4 thru 4 150 B84 C38 6

ASTM A563 - Grade DHCarbon Steel


1/4 thru 4 175 C24 C38 6

ASTM A563 - GradeDH3


Resistant Steel,Quenched

and Tampered

1/4 thru 4 175 C24 C38 5,9

ASTM A194 - Grade 1 Carbon Steel 1/4 thru 4 130 B70 -- 7

ASTM A194 - Grade 2Medium Carbon

Steel1/4 thru 4 150 159 352 7,8


28/39

ASTM A194 - Grade 2HMedium CarbonSteel, Quenchedand Tempered

1/4 thru 4 175 C24 C38 7

ASTM A194 - Grade2HM


1/4 thru 4 150 159 237 7,8

ASTM A194 - Grade 4

Medium Carbon

Alloy Steel,Quenched

and Tempered

1/4 thru 4 175 C24 C38 7

ASTM A194 - Grade 7

Medium CarbonAlloy Steel,Quenched

and Tempered

1/4 thru 4 175 C24 C38 7

ASTM A194 - Grade 7M

Medium CarbonAlloy Steel,Quenched

and Tempered

1/4 thru 4 150 159 237 7

See Note 1,2 10

LIMITATIONS ON USE OF FASTENERS AND WELDSStructural steel fabricators prefer that job specifications state that shop connections shall be

made with bolts or welds rather than restricting the type of connection that can be used. This

allows the fabricator to make the best use of available equipment and to offer a more competitive

price. For bridges, however, standard specifications restrict fastener choice.

High-strength bolts may be used in either slip-critical or bearing-type connections subject to

various limitations. Bearing-type connections have higher allowable loads and should be used

where permitted. Also, bearing-type connections may be either fully tensioned or snug-tight,

subject to various limitations. Snug-tight bolts are much more economical to install and should

be used where permitted.

Bolted slip-critical connections must be used for bridges where stress reversal may occur or

slippage is undesirable. In bridges, connections subject to computed tension or combined shear

and computed tension must be slip-critical. Bridge construction requires that bearingtype

connections with high-strength bolts be limited to members in compression and secondary

members.

Carbon-steel bolts should not be used in connections subject to fatigue.


29/39

Connections and Fasteners for Cold Form Steel

Because of the wall thinness of cold-formed sections, conventional method for connection used

in steel construction, such as bolting and arc-welding are, of course, available but are generally

less appropriate and emphasis is on special techniques, more suited to thin materials. Long-

standing methods for connecting two elements thin material are blind rivets and self drilling, self

tapping screws. Fired pins are often used to connect thin materials to a ticker supporting

member. More recently, press-joining or clinching technology (Predeschi, 1997) which is very

productive requires no additional components and causes no damage to the galvanising or other

metallic coating. This technology has been taken from the automotive industry, but actually it is

successfully used in building construction. Rosette system is another innovative connectingtechnology (Makelainen P. and Kesti J., 1999), proper to cold-formed steel structures. Therefore,

connection technology of cold-formed steel structures is representing one of their particular

advantages, both in manufacturing and erection process.


30/39

Usual mechanical fasteners for commonapplications


31/39


32/39

19: Bolt head shapes

Fig. 20: Bolted continuous fixation for purlins and side rails


33/39

Fig. 21: Failure modes for bolted connections in shear

Fig. 22: Possible failure modes for bolted connections in tension


34/39

Fig. 23: Thread types for thread-forming screws

Fig. 24: Thread and points of thread-cutting screws


35/39

Fig. 25: Self-drilling screws: a) drill diameter equal to body diameter for thin-to-thick connections; b)drill diameter smaller than body diameter for thin-to-thin connections

Fig. 26: Washers for self-tapping screws: a) metal washer; b) elastomeric washer; c) and d)

elastomeric or vulcanised to metal washer


36/39

Fig. 28: Different types of blind rivets


37/39

Fig. 29: Nut systems


38/39

Five types of powder actuated fasteners

Three types of air driven fasteners

Fig. 30: Shot fired pins


39/39

Reference

George E. Totten. 2004. Steel Heat Treatment- Metallurgy and Technologies. 2nd edition. Taylor

& Francis Production

Michael F. Ashby. 1998. Engineering Materials 1- An lntroduction to their Properties and

Applications. 2nd edition. Butterworth Heinemann Production

Michael G. Goode. 2004. Fire Protection of Structural Steel in High-Rise Buildings. U.S.

Department of Commerce Technology Administration National Institute of Standards and

Technology

Roger L. Brockenbrough. 2001. STRUCTURAL STEEL DESIGNERS HANDBOOK. 3rd

edditon. McGRAW-HILL, INC.

Robert E. Reed-Hill. 1996. Physical Metallurgy Principles. 2nd edition. D. Van Nostrand

Company

Tunnplat. 2001. Hot Rolled Cold Forming Steel. Domex 240 YP. Domec Publication

Documents

Assignment Civ 428