ME 215 – Engineering Materials I

Chapter 1

Engineering Materials (Part I)Engineering Materials (Part I)

D A T l B dM h i l E i i Dr. A. Tolga Bozdanawww.gantep.edu.tr/~bozdana

Mechanical EngineeringUniversity of Gaziantep

Introduction

Materials used in engineering applications cover a wide rangefrom simple daily uses (e.g. pencils, spoons) to most complex andp y ( g p , p ) pextreme cases (e.g. space shuttles, biomedical purposes).

Properties of such materials are of joint interest to the metallurgist,the material scientist and the engineerthe material scientist, and the engineer.

Compared with material scientist and metallurgist engineer doesCompared with material scientist and metallurgist, engineer doesnot require deep understanding of the subject, but needs to knowwhich properties are important in different circumstances andwhich properties are important in different circumstances andwhat limitations he could be faced with.

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Engineering Materials

Metals and Alloys Non-metals

Ferrous (iron based) Metals Naturals: Wood Granite etcFerrous (iron based) Metals

Cast Iron (%C > 2):Gray White Ductile Malleable High alloy

Naturals: Wood, Granite, etc.

ArtificialsGray, White, Ductile, Malleable, High alloy

Steel (%C < 2):Plain Carbon steels Alloy steels

Polymers:Rubber, Thermoplastics, Thermosets

Non-ferrous (iron free) Metals

Plain Carbon steels, Alloy steelsCeramics:Glass, Cermets

Heavy Metals:Copper, Chromium, Lead, etc.

Composites:Metal matrix composites,Ceramic matrix composites

Light Metals:Titanium, Beryllium, etc.

Ceramic matrix composites,Polymer matrix composites

Refractory (High Temp.) Metals:Tungsten, Molybdenum, etc.

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Precious Metals:Gold, Silver, etc.

Metals vs. Artificials

Metals are used to be the main engineering materials preferredby mechanical engineers for centuries.y g

The main reasons for this were their existence in nature, easyprocessing and also their relatively more load carrying capacity.

However, artificial materials took place in many applicationsdue to their advantages such as better insulation, heat resistanceand weight saving.

Therefore, many different materials were found or derived fromother materials for certain advantages in different applicationsother materials for certain advantages in different applications.

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Ferrous Metals

Ferrous metals are classified as cast irons (with > 2% C) andsteels (with < 2% C).( )

They are the most widely used materials in many engineeringapplications.

Steel, in particular, has many versions (alloys) with differentadvantages for different applications.

Steel can serve in applications varying from simple machineconstruction to extreme load bearing (carrying) applications andfrom simple springy (elastic) deflection applications to very hightemperature resistant or corrosion resistant applications.

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Steel Making

Steels are made by removing excess C and other impurities of pigiron by “oxidation” process followed by “deoxidation” process,y p y p ,and addition of C and other alloying elements to the required level.

Oxidation is carried out by blowing air or oxygen through moltenpig iron in either of following furnaces:pig iron in either of following furnaces:

1. Bessemer-Thomas Furnace2. Siemens-Martin (Open Heart) Furnace3. Basic Oxygen Furnaceyg4. Electric Furnace

Steels can contain up to 2% Carbon (C), 1% Manganese (Mn),0 5% Silicon (Si) 0 05% Sulfur (S) and 0 05% Phosphorus (P)

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0.5% Silicon (Si), 0.05% Sulfur (S) and 0.05% Phosphorus (P).

Steel Making Flowline (AISI Flow Sheet)The pig iron is eithertransformed into castiron or converted into

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steels by a secondaryprocess.

The product of blast furnace iscalled pig iron (i.e. impure iron)containing too much C, Mn, P,

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Iron is found in nature as iron ore which consist of iron oxides, carbonates and sulphides and gaunge.

co ta g too uc C, , ,S and Si.

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Iron is obtained by reduction of iron oxides with carbon (i.e. coke) in the blast furnace.

Limestone is usually added into the blast furnace to remove gaunge (i.e. SiO2 as calcium silicate slags).

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Steel Finishing Flowline (AISI Flow Sheet)

The steels in the form6of slabs, blooms andbillets are formed intoplates, coils and sheetsas well as tubes barsas well as tubes, barsand rods, and variousstructural shapes.

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Plain Carbon SteelsThis is the first group of steels in which C is the significant alloying addition. Theycontain up to 1.5% C and also 1.65% Mn (max), 0.6% Si (max), 0.6% Cu (max).

A. Low Carbon Steels

A1. Dead-soft mild steels: < 0.15% C. Very soft, easily fabricated by cold forming0 5% C y , y y gand welding. Used in construction where strength is not very important.

A2. Mild steels: 0.15 - 0.30% C. Also known as “structural steels”. Used forstructure, structure and machine applications, structural shapes like I-beams,channels, angles etc.

B. Medium Carbon Steels: 0.30 - 0.60% C. Having combined properties of strength,toughness and wear resistance. Used for crankshafts, axles, railway wheels, gears.

C. High Carbon Steels: 0.30 - 1.5% C. With low ductility. Used for high speed steels(HSS) wire production etc(HSS), wire production, etc.

D. Free Machining Carbon Steels: Specially developed for fast and economic

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machining. Machinability of plain carbon steels is improved by addition of someelements such as Pb (lead), S, P, Te (tellurium), Se (selenium), and Bi (bismuth).

Alloy SteelsThis is the second group of steels which contain modest amount of alloyingelements. They usually contain more than 1.65% Mn, 0.60% Si and 0.60% Cu.

They can be heat treated to improve some mechanical properties. They havethrough hardenable grades, carburizing grades, and nitriding grades.

The alloying elements to be added into alloy steels may:

Form solid solution or intermetalic compounds in steelForm solid solution or intermetalic compounds in steel.

Alter the temperature at which phase transformations occur.

Alter the solubility of C in different phases of ironAlter the solubility of C in different phases of iron.

Alter the rate of transformation of austenite to its decomposition products(i.e. the solution of cementite into austenite upon heating).( p g)

Decrease the softening on tempering.

Nearly all alloying elements dissolve in both ferrite and austenite, and increasestrength and hardenability of steels. Non-metalic inclusions (such as oxides

d l hid ) d idi d i h ll S l hid d

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and sulphides) are deoxidizers and grain growth controllers. Sulphides andnitrides increase hardness.

Effects of Alloying ElementsManganese (Mn): (1.65-2.1%) increases strength, hardenability, corrosion resistance.

Titanium (Ti): increases yield point and weldability.

Chromium (Cr): increases hardness, hardenability, wear resistance, corrosion resistance.

Wolfram or Tungsten (W): increases hardness and tensile strength.

( ) , y, ,

Molybdenum (Mo): used with Mn & Cr to increase hardenability, tensile, creep strength.

Vanadium (V): increases hardenabilityVanadium (V): increases hardenability.

Nickel (Ni): increases strength, shock resistance, corrosion resistance, heat resistancewhile lowers critical temp for heat treatmentwhile lowers critical temp. for heat treatment.

Carbon (C): increases hardness & tensile strength, decreases forging & welding properties.

Phosphorus (P): (0.03-0.05%) harmful (make steel brittle and prevent hot/cold forming).

Sulfur (S): (0.025-0.05%) harmful (make steel brittle and prevent hot/cold forming).

Aluminium (Al): promotes nitriding properties.

Silicon (Si): (0 6 2 2%) raises critical temp for heat treatment and increases resilience

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Silicon (Si): (0.6-2.2%) raises critical temp. for heat treatment and increases resilience.

Elemental Copper (Cu) & Lead (Pb): increase machinability.

Alaşım Elementlerinin Çeliklerin Özelliklerine Etkileri

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High Alloy SteelsThey are specially produced for specific purposes by using certain alloying elements.

A Tool Steels: clean (no inclusion) steels produced in electric furnaces They usuallyA. Tool Steels: clean (no inclusion) steels produced in electric furnaces. They usuallycontain Cr, V, W, Mo or Co besides C, Mn, Si. They have wear resistance, hightoughness and high hot hardness. These steels are used mainly in tools and dies.g g y

B. Stainless Steels: contain 10.5% Cr (min). They have high strength, hardness,corrosion resistance and abrasion resistance Addition of higher amo nt of Cr and Nicorrosion resistance and abrasion resistance. Addition of higher amount of Cr and Niimproves corrosion resistance.

C. High Strength Steels: developed for specific high strength applications and usedfor weight saving in constructions.

D. High Strength Low Alloy (HSLA) Steels: specially developed for improvingmechanical properties and corrosion resistance while benefitting from weight saving.p p g g g

E. Iron Based Super Alloys: cheaper than Co and Ni based super alloys, and usedfor high temperature applications Super alloys are usually used at temperatures

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for high temperature applications. Super alloys are usually used at temperaturesfrom 540 to 1090 ºC. Iron based super alloys are used at lower end of this range.

Cast Iron

Cast iron is a “four-element alloy” containing iron, carbon (2 - 4%),silicon and manganese. Some grades may contain additionalg g yalloying elements.

Cast iron contains large amount of carbon in the form of Fe3C(cementite). This composition is not stable and decomposes under( ) p pcertain conditions: Fe3C → 3Fe + C

According to this breakdown of cementite, cast irons are classified:

Gray CIGray CIDuctile CIWhit CIWhite CIMalleable CI

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High alloy CI

Types of Cast IronGray CI:

It gives gray fracture surface.g g y

Widely used in engineering applications.

In manufacture cementite separetes into graphite and austenite or ferriteIn manufacture, cementite separetes into graphite and austenite or ferriteby controlling the alloy composition and cooling rates.

M t CI “h t t id ll ” t i i 2 5 4% CMost gray CI are “hypoeutectoid alloys” containing 2.5 - 4% C.

Individual grades depend upon the amount of graphite distribution patternand structure of iron around it.

Ductile (Nodular) CI:Ductile (Nodular) CI:It is alloyed with magnesium which precipitates out carbon in the form ofsmall spheres This improves some mechanical properties of gray CIsmall spheres. This improves some mechanical properties of gray CI.

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Types of Cast IronWhite CI:

Produced by “chilling” preventing graphite carbon from precipitating out.y g p g g p p p g

Either gray CI or ductile CI can be chilled to produce a white surface.

Most of carbon is combined with iron as iron carbide (cementite) which isMost of carbon is combined with iron as iron carbide (cementite) which isa very hard material. Grades of white CI depend on the amount ofcementite in the surrounding structurecementite in the surrounding structure.

Malleable CI:Malleable CI:White CI is converted to malleable condition by two-stage heat treatment.

Malleable CI differs from others in the shape of contained graphiteMalleable CI differs from others in the shape of contained graphiteexisting as tempered carbon nodules as compared with graphite flakes ingray CI and true carbon spheroids in ductile CIgray CI and true carbon spheroids in ductile CI.

Two basic types are ferritic and pearlitic. The third type (martensitic) ispearlitic or ferritic grade that has been heat treated and transformed to

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pearlitic or ferritic grade that has been heat treated and transformed tomartensitic structure.

Types of Cast IronHigh Alloy CI:

They are ductile, gray or white CI containing over 3% alloy content.y , g y g y

They are usually produced in specialized foundries, and their propertiesare significantly different from unalloyed CIare significantly different from unalloyed CI.

Selection of the proper alloy for a casting is difficult since properties ofthe finished part depend strongly upon size and shape of the partthe finished part depend strongly upon size and shape of the part.This is very important to bear in mind when deciding on casting process.

Gray CI Ductile CI White CI Malleable CI

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Gray CI Ductile CI White CI Malleable CI

Designation of Steels

There are various standardization bodies for steels:

1 American (AISI & ASTM)1. American (AISI & ASTM)2. German (DIN)3 T ki h (TS & MKE)3. Turkish (TS & MKE)4. British (BS)5. Euronorm

Steels are usually designated by the criteria of:

Process of manufactureMethod of deoxidationChemical compositionMechanical properties

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Mechanical properties

Designation by Process of ManufactureThe purification of pig iron into steel is accomplished by followingmethods (the last two are the most widely used processes):

1. Basic Thomas or acid Bessemer converter2. Open heart furnace3. Electric furnace4. Basic oxygen furnace

The prefixes are used to designate steels produced by above methods:

Turkish and DIN standards

T – Thomas converter

American (AISI) standards

A – Basic open hearth alloy TOM

––

Thomas converterOxygen converterOpen hearth furnace

ABC

––

Basic open hearth alloyAcid Bessemer carbonBasic open hearth carbon M

EI

––

Open hearth furnaceElectric arc furnaceInduction furnace

CDE

––

Basic open hearth carbonAcid open hearth carbonElectric arc furnace alloy

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I – Induction furnaceEX

––

Electric arc furnace alloyComposition varies from normal limits

Designation by Method of DeoxidationIn steel making process, the primary reaction is the combination of carbonand oxygen to form a gas. If the oxygen is not removed prior to or duringcasting (by the addition of ferro-silicon or some other deoxidizer), thengaseous products continue to evolve during solidification. This will causenon-uniformity in microstructure of the steel. Proper control of the amountof gas evolved during solidification determines the type of steel.

Based on type of deoxidation, the steels are classified as below andd i t d b th l tt fidesignated by the letter prefixes:

Type TS DIN

Rimmed K U

Semi-killed Sy HSemi killed Sy H

Killed S R

S i ll kill d RR

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Specially killed – RR

Designation by Method of DeoxidationKilled steels are completely deoxidized steels (i.e. no formation of carbonmonoxide). Aluminum and silicon may be added to combine chemically withthe oxygen removing most of it from liquid steel Ingots and castings of killedthe oxygen, removing most of it from liquid steel. Ingots and castings of killedsteels have homogeneous structure and no gas porosity (blowholes).Therefore, killed steels are recommended for hot forging, carburizing, piercingTherefore, killed steels are recommended for hot forging, carburizing, piercingand heat-treating applications where maximum uniformity is required.

S ( )Semi-killed (capped) steels are incompletely deoxidized steels containing someexcess oxygen, which forms carbon monoxide during last stages of solidification.These steels have relatively less uniform properties and composition due toThese steels have relatively less uniform properties and composition due tosegregation (i.e. nonuniform variation in internal characteristics that results whenvarious alloying elements redistribute themselves during solidification).y g g )

For rimmed steels (with less than 0.25% C and 0.60% Mn), oxygen in the formof carbon mono ide e ol es q ickl thro gho t the solidification process Ingotsof carbon monoxide evolves quickly throughout the solidification process. Ingotsof rimmed steels are characterized by practically carbon-free surface withconsiderable quantity of blowholes. The outer skin of these steels is very

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considerable quantity of blowholes. The outer skin of these steels is veryductile, hence they are often specified for cold-forming applications.

Designation by Chemical CompositionFollowing steel groups are designated by their chemical compositions:

1. Plain carbon steels1. Plain carbon steels2. Alloy steels3 T l t l3. Tool steels4. Stainless steels5. HSLA steels6. Super alloys

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Designation of Plain Carbon SteelsThe general designation for plain carbon steels (which have only carbon as alloyingelement) is CiXX where “XX/100” is carbon percentage and “i” refers to grade ofcontrol of some alloying elements and some mechanical propertiescontrol of some alloying elements and some mechanical properties.

Designation C % Designated byC 10 0 07 0 13 DIN TS

* The letters “k” and “m” designate howclosely P and S content are controlledC 10 0.07 – 0.13 DIN, TS

Ck 10* 0.07 – 0.13 DIN, TSCm 35* 0 32 – 0 39 DIN TS

closely P and S content are controlled.The letter “f” specifies a steel suitablefor superficial hardening, and “q”

ifi t l f ld t iCm 35 0.32 0.39 DIN, TSCf 35* 0.32 – 0.39 DIN, TSCq 35* 0.32 – 0.39 DIN, TS

specifies a steel for cold extrusion.

** These designations have no inferenceto carbon content “En” designation isq

CC 10 0.05 – 0.15 AFNOR (France)S 10 C 0.08 – 0.13 JIS (Japan)

to carbon content. “En” designation isreplaced by the new “BS” designation(e.g. a steel (0.16-0.24% C) designated

S )A 12 0.08 – 0.16 GOST (Russia)En 2C** 0.18 – 0.23 BS (British)1225** 0 08 SIS (S d )

as “En 3” is now “BS 070M20”).

*** “St” is the old DIN designation that istill d i T k f t l1225** 0.08 SIS (Sweden)

1010*** 0.08 – 0.13 AISI, SAE (USA)Ç1060*** 0 55 0 64 MKE (Turkey)

still used in Turkey for some steelproducts (e.g. “16.61” is cementationsteel with 0.16% C). For AISI and MKE,

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Ç1060 0.55 – 0.64 MKE (Turkey)St C 16.61*** 0.10 – 0.18 DIN (German)

the numeral “1” stands for carbon steeland “10” designates plain carbon steel.

Designation of Alloy SteelsIn Turkey, mainly DIN and AISI designations are used. In DIN designation,multiplication factors are used for the content of alloying elements:

Factor for Co, Cr, Mn, Ni, Si, W = x 4Factor for Al, Cu, Mo, Ti, V = x 10

Steel Average Percentage If Al (0 1%) Cu (0 25%) Mn (0 8%) Si

Factor for C, N, P, S = x 100

Steel Average Percentage14 NiCr 10 0.14% C, 2.5% Ni15 CrNi 6 0 15% C 1 5% Cr

If Al (0.1%), Cu (0.25%), Mn (0.8%), Si(0.5%) and Ti (0.1%) are not exceeded,such as steel is considered unalloyed.

15 CrNi 6 0.15% C, 1.5% Cr13 Cr 2 0.13% C, 0.5% Cr16 MnCrS 5 0.16% C, 1.25% Mn

Low alloy steels contain not more than 5%of alloy elements. When alloy contents16 MnCrS 5 0.16% C, 1.25% Mn

20 MoCr 4 0.20% C, 0.4% Mo39 CrMoV 13 9 0.39% C, 3.25% Cr, 0.9% Mo

exceed 5% (i.e. high alloy steels), thesemultiplication factors are not used(except for carbon) Instead the letter39 CrMoV 13 9 0.39% C, 3.25% Cr, 0.9% Mo

9 S 20 0.09% C, 0.2% SX120 Mn 12 1.20% C, 12% Mn

(except for carbon). Instead, the letter“X” is put in front of carbon contentindicating that the number(s) at the end of

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,X12 CrNi 18 9 0.12% C, 18% Cr, 9% Ni designation specify the alloy content.

Designation of Alloy SteelsAISI (SAE) and MKE designations use 4-digit numbers: “XXXX”

Th fi t t di it i di t th ll l ifi ti d th l t tThe first two digits indicate the alloy classification, and the last two(and in special cases, three) digits give the carbon content (x100).See next page for complete tableSee next page for complete table.

For instance plain carbon steels is denoted by the basic numeral 10For instance, plain carbon steels is denoted by the basic numeral 10.Thus, “Steel 1030” indicates a plain carbon steel containing 0.30% C.

In some cases, capital letter prefixes or suffixes are added to designatethe type of process or hardenability. Some examples for the prefixes are:

C1020 (C: for basic open heart carbon)B1112 (B: for acid bessemer carbon)( )A3140 (A: for basic open hearth alloy)E52100 (E: for electric arc furnace alloy)

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E52100 (E: for electric arc furnace alloy)

Designation of Alloy SteelsCarbon Steels 1xxx Molybdenum Steels 4xxx

Plain Carbon 10xx Carbon-Molybdenum 40xx

Free Cutting 11xx Chromium-Molybdenum 41xx

Free Cutting “Leaded” 12Lxx * Chromium-Nickel-Molybdenum 43xx

M St l 13 Ni k l M l bd (1 75% Ni) 46Manganese Steels 13 xx Nickel-Molybdenum (1.75% Ni) 46xx

Nickel Steels 2xxx Nickel-Molybdenum (3.50% Ni) 48xx

3 50% Ni 23xx Chromium Steels 5xxx3.50% Ni 23xx Chromium Steels 5xxx5.00% Ni 25xx Low Chromium 51xx

Nickel-Chromium Steels 3xxx Medium Chromium 52xxc e C o u Stee s 3 ed u C o u 5

1.25% Ni, 0.60% Cr 31xx Corrosion and Heat Resistant 51xx

1.75% Ni, 1.00% Cr 32xx Chromium-Vanadium Steels 6xxx3.50% Ni, 1.50% Cr 33xx 1.00% Cr 61xx

Tungsten Steels 7xxx(x) ** Silicon-Manganese Steels 9xxxChromium-Nickel-Molybdenum 86xx, 87xx 2.00% Si 92xx* The letter “L” (as in 12L13 steel) signifies a free cutting steel to which lead is added to improve machinability.

Likewise, the letter “B” (e.g. 81B45) signifies a minimum of 0.0005% boron added for hardenability.

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Likewise, the letter B (e.g. 81B45) signifies a minimum of 0.0005% boron added for hardenability.The steels to meet certain hardenability requirement are designated by suffix “H” (e.g. 8637H, 94B15H, etc.)

** Used for certain tungsten alloys by SAE and MKE, such as 7245, 72100 and 71660.

Designation of Tool SteelsThese steels are divided into four broad groups as follows:

Group German Turkishp

1 Carbon Tool Steels Unalloyed Carbon Tool Steels

2 High-Speed Steels Alloyed Tool Steels2 High Speed Steels Alloyed Tool Steels

3 Cold Work Tool Steels Cold Work Tool Steels

4 Hot Work Tool Steels Hot Work Tool Steels4 Hot Work Tool Steels Hot Work Tool Steels

Group 1: Carbon Tool SteelsGroup 1: Carbon Tool SteelsDesignation of carbon tool steels is the same as that of carbon steels. The onlydifference is that a quality symbol follows the usual designation.difference is that a quality symbol follows the usual designation.

The quality symbol is "W" (W1, W2, W3) denoting an increase in the quality inthe order of special, extra, best quality. The symbol “WS” denotes a specialp q y y ppurpose tool steel (also used by Asil Çelik).

Some examples are: C125WS (1.25% C with special quality), C110W2, C60W3.

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p ( p q y)

Designations by MKE and AISI are: Ç1090, Ç10100, Ç10115, etc.

Designation of Tool SteelsGroup 2: High Speed Steels

They are designated as: “S xx-yy-zz-uu” where “S” denotes high speed steel,“xx-yy-zz-uu” is content of W-Mo-V- Co using no multiplication factors:“S 10-4-3-10” means 10% W, 4% Mo, 3% V, 10% Co

“S 18 0 1” 18% W 0% M 1% V 0% C“S 18-0-1” means 18% W, 0% Mo, 1% V, 0% Co

Group 3 & 4: Cold & Hot Work Tool Steels

They are designated according to the designation of alloy.

DIN and ASİL Çelik uses the same designation as explained previously:“40NiMo10 8” means 0.40% C, 2.5% Ni, 0.8% Mo

MKE uses basic AISI designation for alloy steels, and tools steels are classifiedinto groups by the AISI. All these groups of tool steels and the correspondingd i ti h i tdesignations are shown in next page.

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Designation of Tool Steels (AISI designation by MKE)

Cold WorkType W (water hardening) Commercial (W1xx), Extra (W2xx), Standard (W3xx), Special (W4, W5, W6, W7)

Type O (oil hardening) O1 O2 O6 O7Type O (oil hardening) O1, O2, O6, O7

Type A (air hardening) A2, A3, A4, A5, A6, A7, A8, A9, A10

Type D (air hardening) D1, D2, D3, D4, D5, D6, D7

Hot WorkType H (chromium grades) H1 - H19

(tungsten grades) H20 - H39

(molybdenum grades) H40 - H59

Hi h S dHigh SpeedType T (tungsten grades) T1, T2, T3, T4, T5, T6, T7, T8, T9, T15

Type M (molybdenum grades) M1, M2, M3-1, M3-2, M4, M6, M7, M8, M10, M15, M30, M33, M34, M35, M36, M41, M42, M43, M44, M46, M47, M50

Shock Resisting (Type S) S1, S2, S3, S4, S5, S6, S7

Special Purpose

Type P (mould steels) P1, P2, P3, P4, P5, P6, P20, P21

T L (l ll t l ) L1 L2 L3 L4 L5 L6 L7

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Type L (low alloy steels) L1, L2, L3, L4, L5, L6, L7

Type F (carbon-tungsten alloy) F1, F2, F3

Designation of Stainless SteelsThese are widely used family of chromium alloys (min. 10.5% Cr), and they areknown for their corrosion resistance.

DIN designation is the same as alloy steels: “X40 Cr 13”, “X12 CrNi 18 8”, “X20Cr 13” are DIN designations of three types of stainless steel produced by MKECr 13 are DIN designations of three types of stainless steel produced by MKE.MKE's own designation of these steels is based on the basic SAE system:“Ç51440”, “Ç3915”, “Ç51420” in the same order.

AISI classifies wrought stainless steels into four groups based on metallurgicalt t d d i ti i il t ll t l t iti (30201 30316structure, and designations are similar to alloy steels: austenitic (30201, 30316,

30347, so on); ferritic (405, 430, 442, 446, 51405 and 51430); martensitic(same as ferritic designation), and precipitation hardening (630 to 605).( g ), p p g ( )

Cast stainless steels are considered as another group. DIN designation of caststainless steels is the same as that of the alloy steels only to be preceeded bythe letter G to indicate casting: G-X12Cr 14, G-X10CrNi 18 8, G-NiMo 30,G X2NiCrMoCuN 25 20 etc

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G-X2NiCrMoCuN 25 20, etc.

Designation of HSLA Steels

Steels of very high strength are usually proprietary, and hence they arenot specified by the standard designations.p y g

However, there are some special designations or trade names. ASTMclassifies these steels into 6 groups based on their chemical compositionand mechanical properties. SAE specifies 12 grades with emphasis onmechanical properties.

Followings are the examples of typical SAE and ASTM designations:

Specification Condition

Followings are the examples of typical SAE and ASTM designations:

SAE J410 C, ASTM A607 Semi-killed or killed

ASTM A606 (Type 2 and 4) Improved corrosion resistance

ASTM 715 (sheet), ASTM A656 (plate) Inclusion controlled, improved formability, killed

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Designation of Super Alloys

Super alloys are designated by AISI 600 series with the specifications ofhigh temperature and high strength:

I. 601-604 : Martensitic low alloy

II. 610-613 : Martensitic second hardening

III. 614-619 : Martensitic chromium steels (616 is equivalent to X20CrMoWV 12 1)

IV. 630-635 : Semiaustenitic and martensitic precipitation hardening stainless steels

V 650-653 : Austenitic steels strengthened by cold/hot workV. 650-653 : Austenitic steels strengthened by cold/hot work

VI. 660-665 : Austenitic super alloys (some of German equivalents are classifiedunder “Aviation Standard”; e.g. No. 1.4944 for 660 and 1.4974 for 661); g )

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Designation by Mechanical PropertiesSteels for general structural purposes are designated by mechanical propertiesby DIN, EURONORM and KARABÜK Demir Çelik (Turkey).

“St xx y” is the DIN designation where “xx” is tensile strength and “y” is quality“St xx-y” is the DIN designation where “xx” is tensile strength and “y” is qualitygrade number denoting maximum contents of P and S:

Symbol Maximum ContentSymbol Maximum ContentUSt 37-1 (rimmed), RSt 37-1 (killed) 0.2% C, 0.07% P, 0.05% SUSt 37-2 (rimmed), RSt 37-2 (killed) 0.17-018% C, 0.05% P, 0.05% S( ), ( )St 37-3 (RR specially killed) 0.17% C, 0.045% P, 0.045% SUSt 42-1, RSt 42-1 0.25% C, 0.08% P, 0.05% SUSt 42-2, RSt 42-2 0.23-0.25% C, 0.05% P, 0.05% SSt 42-3 0.23% C, 0.045% P, 0.045% SRSt 46-2 0.2% C, 0.05% P, 0.05% SSt 46-3 0.2% C, 0.045% P, 0.045% S

In Euronorm; Fe is substituted for symbol St,the letters (A-D) are used instead of qualitynumbers (1 3) and the yield strength is used

DIN EuronormUSt 34-1 Fe 34-A

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numbers (1-3) and the yield strength is usedinstead of tensile strength:

RSt 34-2 Fe 34-B3FNSt 37-3 Fe 37-C3FN

Designation of Cast IronsIt is not possible to specify cast iron by a standard chemical analysis. A singleanalysis of cast iron can produce entirely different types of iron, depending uponf d ti h d i f ti ll f hi h i fl li tfoundry practice, shape and size of casting; all of which influence cooling rate.Thus, iron is usually specified by mechanical properties.

Designation of Gray CI:It is designated by its tensile

Standard DesignationTS 1111 (T ki h) DDL XX (k / )It is designated by its tensile

strength. Some examples ofstandards and corresponding

TS 1111 (Turkish) DDL – XX (kg/mm2)

DIN 1691 (German) GL – XX (kg/mm2)

ASTM A48 (A i ) Cl XX (lb/i 2 1000)designations are shown (“xx”is the tensile strength):

ASTM A48 (American) Class – XX (lb/in2 x 1000)

BS 1452 (British) Grade – XX (MPa)

Designation of White CI:

Unlike gray CI, there are no specifications for white CI.

Symbols of “DDB” and “GGW” are used to designate white iron in short form by

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TS and DIN, respectively.

Designation of Cast Irons

Designation of Ductile (Nodular) CI:It is designated by three-letter abbreviation followed by its tensile strength (“xx” ing y y g (kg/mm2) such as “DDK-XX” in TS 1111 and “GGG-XX” in DIN 1693.

ASTM designation (A339-55 and A396-58) of a typical alloy is: “xx-yy-zz” where“xx” is the minimum tensile strength (in psi), “yy” is the minimum yield strength(in psi), and “zz” is the percentage of elongation over 20 inches gauge.

Designation of Malleable CI:It is designated as “DDTS-xx” and “DDTB-xx” in TS 1111 and “GTS-xx” and“GTW-xx” in DIN 1692 where “xx” is the minimum tensile strength.

ASTM d i ti i b d 5 di it t “ ” h “ ” lti li dASTM designation is based on 5-digit system: “xxxyy” where “xxx” multipliedby 100 is the yield strength (in psi) and “yy” is % elongation over 2 inches gaugelength (e.g. “32510” means Sy = 32500 psi with 10% elongation).g ( g y p g )

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