steel heat treatment handboook-metalluurgy and technologies

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Preface

The first edition of the Steel Heat Treatment Handbook was initially released in 1997. The

objective of that book was to provide the reader with well-referenced information on the

subjects covered with sufficient depth and breadth to serve as either an advanced under-

graduate or graduate level text on heat treatment or as a continuing handbook reference for

the designer or practicing engineer. However, since the initial release of the first edition of the

Steel Heat Treatment Handbook, there have been various advancements in the field that

needed to be addressed to assure up-to-date coverage of the topic. This text, Steel Heat

Treatment: Metallurgy and Technologies, is part of a revision of the earlier text. Some of the

chapters in this text are updated revisions of the earlier book and others are completely new

chapters or revisions. These chapters include:

Chapter 1. Steel Nomenclature (Revision)

Chapter 2. Classification and Mechanisms of Steel Transformations (New Chapter)

Chapter 3. Fundamental Concepts in Steel Heat Treatment (Minor Revisions)

Chapter 4. Effects of Alloying Elements on the Heat Treatment of Steel (Minor Revisions)

Chapter 5. Hardenability (Minor Revisions)

Chapter 6. Steel Heat Treatment (Minor Revisions)

Chapter 7. Heat Treatment with Gaseous Atmospheres (Revision)

Chapter 8. Nitriding Techniques, Ferritic Nitrocarburizing, and Austenitic Nitrocarburiz-

ing Techniques and Methods (Revision)

Chapter 9. Quenching and Quenching Technology (Revision)

Chapter 10. Distortion of Heat-Treated Components (New Chapter)

Chapter 11. Tool Steels (New Chapter)

Chapter 12. Stainless Steel Heat Treatment (New Chapter)

Chapter 13. Heat Treatment of Powder Metallurgy Steel Components (New Chapter)

Approximately a third of the book is new and a third of the book is significantly revised

versus the first edition of the Steel Heat Treatment Handbook. This new text is current with

respect to heat treatment technology at this point at the beginning of the 21st century and is

considerably broader in coverage but with the same depth and thoroughness that character-

ized the first edition.

Unfortunately, my close friend, colleague and mentor, Dr. Maurice A.H. Howes, who

helped to bring the first edition of Steel Heat Treatment Handbook into fruition was unable to

assist in the preparation of this second edition. However, I have endeavored to keep the same

consistency and rigor of coverage as well as be true to the original vision that we had for this

text as a way of serving the heat treatment industry so that this book will be a value resource

to the reader in the future.

George E. Totten, Ph.D., FASM

Portland State University

Portland, Oregon

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Editor

George E. Totten, Ph.D. is president of G.E. Totten & Associates, LLC in Seattle, Washing-

ton and a visiting professor of materials science at Portland State University. He is coeditor of

a number of books including Steel Heat Treatment Handbook, Handbook of Aluminum,

Handbook of Hydraulic Fluid Technology, Mechanical Tribology, and Surface Modification

and Mechanisms (all titles of CRC Press), as well as the author or coauthor of over 400

technical papers, patents, and books on lubrication, hydraulics, and thermal processing. He is

a Fellow of ASM International, SAE International, and the International Federation for

Heat Treatment and Surface Engineering (IFHTSE), and a member of other professional

organizations including ACS, ASME, and ASTM. He formerly served as president of

IFHTSE. He earned B.S. and M.S. degrees from Fairleigh Dickinson University, Teaneck,

New Jersey and a Ph.D. degree from New York University, New York.

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Contributors

S.S. Babu

Edison Welding Institute

Columbus, Ohio

Elhachmi Essadiqi

CANMET, Materials Technology

Laboratory

Ottawa, ON, Canada

Johann Grosch

Institut fuer Werkstofftechnik

Technische Universitaet

Berlin, Germany

Bozidar Liscic

Faculty of Mechanical Engineering and

Naval Architecture

University of Zabreb

Zabreb, Croatia

Guoquan Liu

Beijing University of Science and Technology

Beijing, China

Michiharu Narazaki

Utsunomiya University

Utsunomiya, Japan

Arnold R. Ness

Bradley University

Peoria, Illinois

Joseph W. Newkirk

University of Missouri-Rolla,

Rolla, Missouri

Angelo Fernando Padilha

University of Sao Paulo

Sao Paulo, Brazil

Ronald Lesley Plaut

University of Sao Paulo

Sao Paulo, Brazil

David Pye

Pye Metallurgical Consulting, Inc.

Meadville, Pennsylvania

Paulo Rangel Rios

Fluminense Federal University

V. Redonda, Brazil

Anil Kumar Sinha

AKS Associates

Fort Wayne, Indiana

Anton Stich

Technical University of Munich

Munich, Germany

Alexey V. Sverdlin

Bradley University

Peoria, Illinois

Hans M. Tensi

Technical University of Munich

Munich, Germany

Sanjay N. Thakur

Hazen Powder Parts, LLC

Hazen, Arkansas

George E. Totten

Portland State University

Portland, Oregon

Chengjian Wu

Beijing University of Science and Technology

Beijing, China

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Contents

Chapter 1 Steel Nomenclature .............................................................................................1

Anil Kumar Sinha, Chengjian Wu, and Guoquan Liu

Chapter 2 Classification and Mechanisms of Steel Transformation .................................91

S.S. Babu

Chapter 3 Fundamental Concepts in Steel Heat Treatment ............................................ 121

Alexey V. Sverdlin and Arnold R. Ness

Chapter 4 Effects of Alloying Elements on the Heat Treatment of Steel ........................ 165

Alexey V. Sverdlin and Arnold R. Ness

Chapter 5 Hardenability ..................................................................................................213

Bozidar Liscic

Chapter 6 Steel Heat Treatment ......................................................................................277

Bozidar Liscic

Chapter 7 Heat Treatment with Gaseous Atmospheres...................................................415

Johann Grosch

Chapter 8 Nitriding Techniques, Ferritic Nitrocarburizing, and

Austenitic Nitrocarburizing Techniques and Methods ................................... 475

David Pye

Chapter 9 Quenching and Quenching Technology ..........................................................539

Hans M. Tensi, Anton Stich, and George E. Totten

Chapter 10 Distortion of Heat-Treated Components ...................................................... 607

Michiharu Narazaki and George E. Totten

Chapter 11 Tool Steels .....................................................................................................651

Elhachmi Essadiqi

Chapter 12 Stainless Steel Heat Treatment ...................................................................... 695

Angelo Fernando Padilha, Ronald Lesley Plaut, and Paulo Rangel Rios

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Chapter 13 Heat Treatment of Powder Metallurgy Steel Components ...........................741

Joseph W. Newkirk and Sanjay N. Thakur

Appendices

Appendix 1 Common Conversion Constants ................................................................ 789

Appendix 2 Temperature Conversion Table .................................................................. 791

Appendix 3 Volume Conversion Table .......................................................................... 801

Appendix 4 Hardness Conversion Tables: Hardened Steel and Hard Alloys ................ 803

Appendix 5 Recommended MIL 6875 Specification Steel Heat

Treatment Conditions ................................................................................805

Appendix 6 Colors of Hardening and Tempering Heats ...............................................815

Appendix 7 Weight Tables for Steel Bars ......................................................................817

Index...................................................................................................................................821

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1 Steel NomenclatureAnil Kumar Sinha, Chengjian Wu, and Guoquan Liu

CONTENTS

1.1 Introduction .................................................................................................................. 2

1.2 Effects of Alloying Elements......................................................................................... 2

1.2.1 Carbon.............................................................................................................. 3

1.2.2 Manganese ........................................................................................................ 3

1.2.3 Silicon ............................................................................................................... 4

1.2.4 Phosphorus ....................................................................................................... 4

1.2.5 Sulfur ................................................................................................................ 4

1.2.6 Aluminum......................................................................................................... 5

1.2.7 Nitrogen............................................................................................................ 5

1.2.8 Chromium......................................................................................................... 5

1.2.9 Nickel................................................................................................................ 5

1.2.10 Molybdenum..................................................................................................... 5

1.2.11 Tungsten ........................................................................................................... 6

1.2.12 Vanadium ......................................................................................................... 6

1.2.13 Niobium and Tantalum .................................................................................... 6

1.2.14 Titanium ........................................................................................................... 6

1.2.15 Rare Earth Metals ............................................................................................ 7

1.2.16 Cobalt ............................................................................................................... 7

1.2.17 Copper .............................................................................................................. 7

1.2.18 Boron................................................................................................................ 7

1.2.19 Zirconium ......................................................................................................... 8

1.2.20 Lead.................................................................................................................. 8

1.2.21 Tin .................................................................................................................... 8

1.2.22 Antimony.......................................................................................................... 8

1.2.23 Calcium............................................................................................................. 8

1.3 Classification of Steels .................................................................................................. 8

1.3.1 Types of Steels Based on Deoxidation Practice.................................................. 9

1.3.1.1 Killed Steels.......................................................................................... 9

1.3.1.2 Semikilled Steels ................................................................................. 10

1.3.1.3 Rimmed Steels.................................................................................... 10

1.3.1.4 Capped Steels ..................................................................................... 11

1.3.2 Quality Descriptors and Classifications............................................................ 11

1.3.3 Classification of Steel Based on Chemical Composition .................................. 13

1.3.3.1 Carbon and CarbonManganese Steels ............................................. 13

1.3.3.2 Low-Alloy Steels ................................................................................ 17

1.3.3.3 High-Strength Low-Alloy Steels ........................................................ 24

1.3.3.4 Tool Steels.......................................................................................... 27

1.3.3.5 Stainless Steels.................................................................................... 33

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1

1.3.3.6 Maraging Steels.................................................................................. 44

1.4 Designations for Steels................................................................................................ 45

1.4.1 SAE-AISI Designations.................................................................................... 46

1.4.1.1 Carbon and Alloy Steels .................................................................... 46

1.4.1.2 HSLA Steels ....................................................................................... 47

1.4.1.3 Formerly Listed SAE Steels ............................................................... 47

1.4.2 UNS Designations ............................................................................................ 47

1.5 Specifications for Steels............................................................................................... 50

1.5.1 ASTM (ASME) Specifications ......................................................................... 50

1.5.2 AMS Specifications .......................................................................................... 51

1.5.3 Military and Federal Specifications.................................................................. 51

1.5.4 API Specifications ............................................................................................ 54

1.5.5 ANSI Specifications.......................................................................................... 66

1.5.6 AWS Specifications .......................................................................................... 66

1.6 International Specifications and Designations............................................................ 66

1.6.1 ISO Designations.............................................................................................. 66

1.6.1.1 The Designation for Steels with Yield Strength ................................. 66

1.6.1.2 The Designation for Steels with Chemical Composition.................... 84

1.6.2 GB Designations (State Standards of China) ................................................... 85

1.6.3 DIN Standards ................................................................................................. 86

1.6.4 JIS Standards.................................................................................................... 86

1.6.5 BS Standards .................................................................................................... 86

1.6.6 AFNOR Standards........................................................................................... 86

References ........................................................................................................................... 87

1.1 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) yieldstrength with excellent ductility to in excess of 1400 MPa yield stress with fracture toughness

up to 100 MPa m2, and (4) associated microstructures produced by solid-state phase trans-formations by varying the cooling rate from the austenitic condition [4].

This chapter describes the effects of alloying elements on the properties and characteristics

of steels, reviews the various systems used to classify steels, and provides extensive tabular

data relating to the designation of steels.

1.2 EFFECTS OF ALLOYING ELEMENTS

Steels contain alloying elements and impurities that must be associated with austenite, ferrite,

and cementite. The combined effects of alloying elements and heat treatment produce an

enormous variety of microstructures and properties. Given the limited scope of this chapter, it

*This figure varies slightly depending on the source. It is commonly taken as 2.11wt% [1] or 2.06wt% [2], while it is

calculated thermodynamically as 2.14wt% [3].


2 Steel Heat Treatment: Metallurgy and Technologies

would be difficult to include a detailed survey of the effects of alloying elements on the iron

carbon equilibrium diagram, allotropic transformations, and forming of new phases. This

complicated subject, which lies in the domain of ferrous physical metallurgy, has been

reviewed extensively in Chapter 2 of this handbook and elsewhere in the literature [4,5,812].

In this section, the effects of various elements on steelmaking (deoxidation) practices and

steel characteristics will be briefly outlined. It should be noted that the effects of a single

alloying element on either practice or characteristics is modified by the influence of other

elements. The interaction of alloying elements must be considered [5].

According to the effect on matrix, alloying elements can be divided into two categories:

1. By expending the g-field, and encouraging the formation of austenite, such as Ni, Co,Mn, Cu, C, and N (these elements are called austenite stabilizers)

2. By contracting the g-field, and encouraging the formation of ferrite, such as Si, Cr, W,Mo, P, Al, Sn, Sb, As, Zr, Nb, B, S, and Ce (these elements are called ferrite

stabilizers)

Alloying elements can be divided into two categories according to the interaction with

carbon in steel:

1. Carbide-forming elements, such as Mn, Cr, Mo, W, V, Nb, Ti, and Zr. They go into

solid solution in cementite at low concentrations. At higher concentrations, they form

more stable alloy carbides, though Mn only dissolves in cementite.

2. Noncarbide-forming elements, such as Ni, Co, Cu, Si, P, and Al. They are free from

carbide in steels, and normally found in the matrix [5,11,12].

To simplify the discussion, the effects of various alloying elements listed below are

summarized separately.

1.2.1 CARBON

The amount of carbon (C) required in the finished steel limits the type of steel that can be made.

As the C content of rimmed steels increases, surface quality deteriorates. Killed steels in the

approximate range of 0.150.30% C may have poorer surface quality and require special

processing to attain surface quality comparable to steels with higher or lower C contents.

Carbon has a moderate tendency for macrosegregation during solidification, and it is

often more significant than that of any other alloying elements. Carbon has a strong tendency

to segregate at the defects in steels (such as grain boundaries and dislocations). Carbide-

forming elements may interact with carbon and form alloy carbides. Carbon is the main

hardening element in all steels except the austenitic precipitation hardening (PH) stainless

steels, managing steels, and interstitial-free (IF) steels. The strengthening effect of C in steels

consists of solid solution strengthening and carbide dispersion strengthening. As the C

content in steel increases, strength increases, but ductility and weldability decrease [4,5].

1.2.2 MANGANESE

Manganese (Mn) is present in virtually all steels in amounts of 0.30% or more [13]. Manga-

nese is essentially a deoxidizer and a desulfurizer [14]. It has a lesser tendency for macro-

segregation than any of the common elements. Steels above 0.60% Mn cannot be readily

rimmed. Manganese is beneficial to surface quality in all carbon ranges (with the exception of

extremely low-carbon rimmed steels) and reduction in the risk of red-shortness. Manganese

favorably affects forgeability and weldability.


Steel Nomenclature 3

Manganese is a weak carbide former, only dissolving in cementite, and forms alloying

cementite in steels [5]. Manganese is an austenite former as a result of the open g-phase field.Large quantities (>2% Mn) result in an increased tendency toward cracking and distortionduring quenching [4,5,15]. The presence of alloying element Mn in steels enhances the

impurities such as P, Sn, Sb, and As segregating to grain boundaries and induces temper

embrittlement [5].

1.2.3 SILICON

Silicon (Si) is one of the principal deoxidizers used in steelmaking; therefore, silicon content

also determines the type of steel produced. Killed carbon steels may contain Si up to a

maximum of 0.60%. Semikilled steels may contain moderate amounts of Si. For example,

in rimmed steel, the Si content is generally less than 0.10%.

Silicon dissolves completely in ferrite, when silicon content is below 0.30%, increasing its

strength without greatly decreasing ductility. Beyond 0.40% Si, a marked decrease in ductility

is noticed in plain carbon steels [4].

If combined with Mn or Mo, silicon may produce greater hardenability of steels [5]. Due

to the addition of Si, stress corrosion can be eliminated in CrNi austenitic steels. In heat-

treated steels, Si is an important alloy element, and increases hardenability, wear resistance,

elastic limit and yield strength, and scale resistance in heat-resistant steels [5,15]. Si is a

noncarbide former, and free from cementite or carbides; it dissolves in martensite and retards

the decomposition of alloying martensite up to 3008C.

1.2.4 PHOSPHORUS

Phosphorus (P) segregates during solidification, but to a lesser extent than C and S. Phos-

phorus dissolves in ferrite and increases the strength of steels. As the amount of P increases,

the ductility and impact toughness of steels decrease, and raises the cold-shortness [4,5].

Phosphorus has a very strong tendency to segregate at the grain boundaries, and causes

the temper embrittlement of alloying steels, especially in Mn, Cr, MnSi, CrNi, and CrMn

steels. Phosphorus also increases the hardenability and retards the decomposition of

martensite-like Si in steels [5]. High P content is often specified in low-carbon free-machining

steels to improve machinability. In low-alloy structural steels containing ~0.1% C, P increases

strength and atmospheric corrosion resistance. In austenitic CrNi steels, the addition of P

can cause precipitation effects and an increase in yield points [15]. In strong oxidizing agent, P

causes grain boundary corrosion in austenitic stainless steels after solid solution treatment as

a result of the segregation of P at grain boundaries [5].

1.2.5 SULFUR

Increased amounts of sulfur (S) can cause red- or hot-shortness due to the low-melting sulfide

eutectics surrounding the grain in reticular fashion [15,16]. Sulfur has a detrimental effect on

transverse ductility, notch impact toughness, weldability, and surface quality (particularly in

the lower carbon and lower manganese steels), but has a slight effect on longitudinal

mechanical properties.

Sulfur has a very strong tendency to segregate at grain boundaries and causes reduction of

hot ductility in alloy steels. However, sulfur in the range of 0.080.33% is intentionally added

to free-machining steels for increased machinability [5,17] .

Sulfur improves the fatigue life of bearing steels [18], because (1) the thermal

coefficient on MnS inclusion is higher than that of matrix, but the thermal coefficient of

oxide inclusions is lower than that of matrix, (2) MnS inclusions coat or cover oxides (such as



alumina, silicate, and spinel), thereby reducing the tensile stresses in the surrounding matrix

[5,10,19].

1.2.6 ALUMINUM

Aluminum (Al) is widely used as a deoxidizer and a grain refiner [9]. As Al forms very hard

nitrides with nitrogen, it is usually an alloying element in nitriding steels. It increases scaling

resistance and is therefore often added to heat-resistant steels and alloys. In precipitation-

hardening stainless steels, Al can be used as an alloying element, causing precipitation-

hardening reaction. Aluminum is also used in maraging steels. Aluminum increases the

corrosion resistance in low-carbon corrosion-resisting steels. Of all the alloying elements, Al

is one of the most effective elements in controlling grain growth prior to quenching.

Aluminum has the drawback of a tendency to promote graphitization.

1.2.7 NITROGEN

Nitrogen (N) is one of the important elements in expanded g-field group. It can expand andstabilize the austenitic structure, and partly substitute Ni in austenitic steels. If the nitride-

forming elements V, Nb, and Ti are added to high-strength low-alloy (HSLA) steels, fine

nitrides and carbonitrides will form during controlled rolling and controlled cooling. Nitro-

gen can be used as an alloying element in microalloying steels or austenitic stainless steels,

causing precipitation or solid solution strengthening [5]. Nitrogen induces strain aging,

quench aging, and blue brittleness in low-carbon steels.

1.2.8 CHROMIUM

Chromium (Cr) is a medium carbide former. In the low Cr/C ratio range, only alloyed cementite

(Fe,Cr)3C forms. If the Cr/C ratio rises, chromium carbides (Cr,Fe)7C3 or (Cr,Fe)23C6 or both,

would appear. Chromium increases hardenability, corrosion and oxidation resistance of steels,

improves high-temperature strength and high-pressure hydrogenation properties, and enhances

abrasion resistance in high-carbon grades. Chromium carbides are hard and wear-resistant and

increase the edge-holding quality. Complex chromiumiron carbides slowly go into solution in

austenite; therefore, a longer time at temperature is necessary to allow solution to take place

before quenching is accomplished [5,6,14]. Chromium is the most important alloying element in

steels. The addition of Cr in steels enhances the impurities, such as P, Sn, Sb, and As, segregating

to grain boundaries and induces temper embrittlement.

1.2.9 NICKEL

Nickel (Ni) is a noncarbide-forming element in steels. As a result of the open g-phase field, Niis an austenite-forming element [5,11,15]. Nickel raises hardenability. In combination with Ni,

Cr and Mo, it produce greater hardenability, impact toughness, and fatigue resistance in

steels [5,10,11,18]. Nickel dissolving in ferrite improves toughness, decreases FATT50% (8C),even at the subzero temperatures [20]. Nickel raises the corrosion resistance of CrNi

austenitic stainless steels in nonoxidizing acid medium.

1.2.10 MOLYBDENUM

Molybdenum (Mo) is a pronounced carbide former. It dissolves slightly in cementite, while

molybdenum carbides will form when the Mo content in steel is high enough. Molybdenum

can induce secondary hardening during the tempering of quenched steels and improves the

creep strength of low-alloy steels at elevated temperatures.



The addition of Mo produces fine-grained steels, increases hardenability, and improves

fatigue strength. Alloy steels containing 0.200.40% Mo or V display a delayed temper

embrittlement, but cannot eliminate it. Molybdenum increases corrosion resistance and is

used to a great extent in high-alloy Cr ferritic stainless steels and with CrNi austenitic

stainless steels. High Mo contents reduce the stainless steels susceptibility to pitting [5,15].

Molybdenum has a very strong solid solution strengthening in austenitic alloys at elevated

temperatures. Molybdenum is a very important alloying element for alloy steels.

1.2.11 TUNGSTEN

Tungsten (W) is a strong carbide former. The behavior of W is very similar to Mo in steels.

Tungsten slightly dissolves in cementite. As the content of W increases in alloy steels, W forms

very hard, abrasion-resistant carbides, and can induce secondary hardening during the

tempering of quenched steels. It promotes hot strength and red-hardness and thus cutting

ability. It prevents grain growth at high temperature. W and Mo are the main alloying

elements in high-speed steels [5,13]. However, W and Mo impair scaling resistance.

1.2.12 VANADIUM

Vanadium (V) is a very strong carbide former. Very small amounts of V dissolve in cementite.

It dissolves in austenite, strongly increasing hardenability, but the undissolved vanadium

carbides decrease hardenability [5]. Vanadium is a grain refiner, and imparts strength and

toughness. Fine vanadium carbides and nitrides give a strong dispersion hardening effect in

microalloyed steels after controlled rolling and controlled cooling. Vanadium provides a very

strong secondary hardening effect on tempering, therefore it raises hot-hardness and thus

cutting ability in high-speed steels. Vanadium increases fatigue strength and improves notch

sensitivity.

Vanadium increases wear resistance, edge-holding quality, and high-temperature strength.

It is therefore used mainly as an additional alloying element in high-speed, hot-forging, and

creep-resistant steels. It promotes the weldability of heat-treatable steels. The presence of V

retards the rate of tempering embrittlement in Mo-bearing steels.

1.2.13 NIOBIUM AND TANTALUM

Niobium (Nb) and tantalum (Ta) are very strong carbide and nitride formers. Small amounts

of Nb can form fine nitrides or carbonitrides and refine the grains, therefore increasing the

yield strength of steels. Niobium is widely used in microalloying steels to obtain high strength

and good toughness through controlled rolling and controlled cooling practices. A 0.03% Nb

in austenite can increase the yield strength of medium-carbon steel by 150 MPa. Niobium-

containing nonquenched and tempered steels, including microalloyed medium-carbon steels

and low-carbon bainite (martensite) steels, offer a greatly improved combination of strength

and toughness. Niobium is a stabilizer in CrNi austenitic steels to eliminate intergranular

corrosion.

1.2.14 TITANIUM

Titanium (Ti) is a very strong carbide and nitride former. The effects of Ti are similar to those

of Nb and V, but titanium carbides and nitrides are more stable than those of Nb and V. It is

widely used in austenitic stainless steels as a carbide former for stabilization to eliminate

intergranular corrosion. By the addition of Ti, intermetallic compounds are formed in

maraging steels, causing age hardening. Titanium increases creep rupture strength through

formation of special nitrides and tends significantly to segregation and banding [15].



Ti, Nb, and V are effective grain inhibitors because their nitrides and carbides are quite

stable and difficult to dissolve in austenite. If Ti, Nb, and V dissolve in austenite, the

hardenability of alloy steels may increase strongly due to the presence of Mn and Cr in steels.

Mn and Cr decrease the stability of Ti-, Nb-, and V-carbides in steels [5].

1.2.15 RARE EARTH METALS

Rare earth metals (REMs) constitute the IIIB group of 17 elements in the periodic table. They are

scandium (Sc) of the fourth period, yttrium (Y) of the fifth period, and the lanthanides of the sixth

period, which include the elements, lanthanum (La), cerium (Ce), praseodymium (Pr), neodym-

ium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb),

dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm; Tu), ytterbium (Yb), and lutecium

(or lutecium, Lu). Their chemical and physical properties are similar. They generally coexist and

are difficult to separate in ore beneficiation and metal extraction so they are usually supplied as a

mixture and used in various mixture states in metallurgical industries. REMs are strong deox-

idizers and desulfurizers, and they also react with the low-melting elements, such as antimony

(Sb), tin (Sn), arsenic (As), and phosphorus (P), forming high-melting compounds and prevent-

ing them from causing the red-shortness and temper embrittlement [21,22]. The effects of REM

on shape control and modification of inclusions would improve transversal plasticity and

toughness, hot ductility, fatigue strength, and machinability. REMs tend strongly to segregate

at the grain boundaries and increase the hardenability of steels [21,23].

1.2.16 COBALT

Cobalt (Co) is a noncarbide former in steels. It decreases hardenability of carbon steels, but

by addition of Cr, it increases hardenability of CrMo alloy steels. Cobalt raises the marten-

sitic transformation temperature of Ms (8C) and decreases the amount of retained austenite inalloy steels. Cobalt promotes the precipitation hardening [5]. It inhibits grain growth at

high temperature and significantly improves the retention of temper and high-temperature

strength, resulting in an increase in tool life. The use of Co is generally restricted to high-speed

steels, hot-forming tool steels, maraging steels, and creep-resistant and high-temperature

materials [13,15].

1.2.17 COPPER

Copper (Cu) addition has a moderate tendency to segregate. Above 0.30% Cu can cause

precipitation hardening. It increases hardenability. If Cu is present in appreciable amounts,

it is detrimental to hot-working operations. It is detrimental to surface quality and exaggerates

the surface defects inherent in resulfurized steels. However, Cu improves the atmospheric

corrosion resistance (when in excess of 0.20%) and the tensile properties in alloy and low-alloy

steels, and reportedly helps the adhesion of paint [6,14]. In austenitic stainless steels, a Cu

content above 1% results in improved resistance to H2SO4 and HCl and stress corrosion [5,15].

1.2.18 BORON

Boron (B), in very small amounts (0.00050.0035%), has a starting effect on the hardenability

of steels due to the strong tendency to segregate at grain boundaries. The segregation of B in

steels is a nonequilibrium segregation. It also improves the hardenability of other alloying

elements. It is used as a very economical substitute for some of the more expensive elements.

The beneficial effects of B are only apparent with lower- and medium-carbon steels, with no

real increase in hardenability above 0.6% C [14]. The weldability of boron-alloyed steels is

another reason for their use. However, large amounts of B result in brittle, unworkable steels.



1.2.19 ZIRCONIUM

Zirconium (Zr) is added to killed HSLA steels to obtain improvement in inclusion charac-

teristics, particularly sulfide inclusions, where modifications of inclusion shape improve

ductility in transverse bending. It increases the life of heat-conducting materials. It is also a

strong carbide former and produces a contracted austenite phase field [5,15].

1.2.20 LEAD

Lead (Pb) is sometimes added (in the range of 0.20.5%) to carbon and alloy steels through

mechanical dispersion during teeming to improve machinability.

1.2.21 TIN

Tin (Sn) in relatively small amounts is harmful to steels. It hasavery strong tendency to segregate

at grain boundaries and induces temper embrittlement in alloy steels. It has a detrimental effect

on the surface quality of continuous cast billets containing small amounts of Cu [24]. Small

amountsofSnandCualsodecrease thehotductilityof steels in theaustenite ferrite region [25].

1.2.22 ANTIMONY

Antimony (Sb) has a strong tendency to segregate during the freezing process, and has a

detrimental effect on the surface quality of continuous cast billets. It also has a very strong

tendency to segregate at grain boundaries and cause temper embrittlement in alloy steels.

1.2.23 CALCIUM

Calcium (Ca) is a strong deoxidizer; silicocalcium is used usually in steelmaking. The combin-

ation of Ca, Al, and Si forms low-melting oxides in steelmaking, and improves machinability.

1.3 CLASSIFICATION OF STEELS

Steels can be classified by different systems depending on [4,6,8]:

1. Compositions, such as carbon (or nonalloy), low-alloy, and alloy steels

2. Manufacturing methods, such as converter, electric furnace, or electroslag remelting

methods

3. Application or main characteristic, such as structural, tool, stainless steel, or heat-

resistant steels

4. Finishing methods, such as hot rolling, cold rolling, casting, or controlled rolling and

controlled cooling

5. Product shape, such as bar, plate, strip, tubing, or structural shape

6. Oxidation practice employed, such as rimmed, killed, semikilled, and capped steels

7. Microstructure, such as ferritic, pearlitic, martensitic, and austenitic (Figure 1.1)

8. Required strength level, as specified in the American Society for Testing and Materials

(ASTM) standards

9. Heat treatment, such as annealing, quenching and tempering, air cooling (normaliza-

tion), and thermomechanical processing

10. Quality descriptors and classifications, such as forging quality and commercial quality

Among the above classification systems, chemical composition is the most widely used basis

for designation and is given due emphasis in this chapter. Classification systems based on

oxidation practice, application, and quality descriptors are also briefly discussed.



1.3.1 TYPES OF STEELS BASED ON DEOXIDATION PRACTICE

Steels, when cast into ingots, can be classified into four types according to the deoxidation

practice or, alternatively, by the amount of gas evolved during solidification. These four types

are called killed, semikilled, capped, and rimmed steels [6,8].

1.3.1.1 Killed Steels

Killed steel is a type of steel from which there is practically no evolution of gas during solidifi-

cation of the ingot after pouring, because of the complete deoxidation, and formation of pipe in

the upper central portion of the ingot, which is later cut off and discarded. All alloy steels, most

Classification bycommercial name

or application

Ferrous alloys

Steel

Plain carbonsteel

Low-carbonsteel

(0.5% C)

Low- and medium-alloy steel

10% alloyingelements

High-alloysteel

>10% alloyingelements

Corrosionresistant

Heatresistant

Wearresistant Duplex

structure

Austeniticferritic

Precipitationhardened

Austenitic

Bainitic

Martensitic

Pearlitic

Ferriticpearlitic

Classificationby structure

Alloys withouteutectic

(

low-alloy steels, andmanycarbon steels areusuallykilled.The continuous castingbillets are also

killed. The essential quality criterion is soundness [2628]. Killed steel is characterized by a

homogeneous structure and even distribution of chemical compositions and properties.

Killed steel is produced by the use of a deoxidizer such as Al and a ferroalloy of Mn or Si;

However, calcium silicide and other special deoxidizers are sometimes used.

1.3.1.2 Semikilled Steels

Gas evolution is not completely suppressed by deoxidizing additions in semikilled steel,

because it is partially deoxidized. There is a greater degree of gas evolution than in killed

steel, but less than in capped or rimmed steel. An ingot skin of considerable thickness is

formed before the beginning of gas evolution. A correctly deoxidized semikilled steel ingot

does not have a pipe but does have well-scattered large blow holes in the top-center half of the

ingot; however, the blow holes weld shut during rolling of the ingot. Semikilled steels

generally have a carbon content in the range of 0.150.30%. They find a wide range of uses

in structural shapes, skelp, and pipe applications. The main features of semikilled steels are

UJ variable degrees of uniformity in composition, which are intermediate between those of

killed and rimmed steels and less segregation than rimmed steel, and (2) a pronounced

tendency for positive chemical segregation at the top center of the ingot (Figure 1.2).

1.3.1.3 Rimmed Steels

Rimmed steel is characterized by a great degree of gas evolution during solidification in the

mold and a marked difference in chemical composition across the section and from the top to

the bottom of the ingot (Figure 1.2). These result in the formation of an outer ingot skin or

rim of relatively pure iron and an inner liquid (core) portion of the ingot with higher

concentrations of alloying and residual elements, especially C, N, S, and P, having lower

melting temperature. The higher purity zone at the surface is preserved during rolling [28].

Rimmed ingots are best suited for the manufacture of many products, such as plates, sheets,

wires, tubes, and shapes, where good surface or ductility is required [28].

The technology of producing rimmed steels limits the maximum content of C and Mn, and

the steel does not retain any significant amount of highly oxidizable elements such as Al, Si, or

Ti. Rimmed steels are cheaper than killed or semikilled steels for only a small addition of

deoxidizer is required and is formed without top scrap.

1 2 3 4 5 6 7 8

Killed Semikilled Capped Rimmed

FIGURE 1.2 Eight typical conditions of commercial steel ingots, cast in identical bottle-top molds, inrelation to the degree of suppression of gas evolution. The dotted line denotes the height to which the

steel originally was poured in each ingot mold. Based on the carbon, and more significantly, the oxygen

content of the steel, the ingot structures range from that of a completely killed ingot (No. 1) to that of a

violently rimmed ingot (No. 8). (From W.D. Landford and H.E. McGannon, Eds., The Making,

Shaping, and Treating of Steel, 10th ed., U.S. Steel, Pittsburgh, PA, 1985.)



1.3.1.4 Capped Steels

Capped steel is a type of steel with characteristics similar to those of a rimmed steel but to a

degree intermediate between that of rimmed and semikilled steels. Less deoxidizer is used to

produce a capped ingot than to produce a semikilled ingot [29]. This induces a controlled

rimming action when the ingot is cast. The gas entrapped during solidification is excess of that

required to counteract normal shrinkage, resulting in a tendency for the steel to rise in the mold.

Capping is a variation of rimmed steel practice. The capping operation confines the time

of gas evolution and prevents the formation of an excessive number of gas voids within the

ingot. The capped ingot process is usually applied to steels with carbon contents greater than

0.15% that are used for sheet, strip, tin plate, skelp, wire, and bars.

Mechanically capped steel is poured into bottle-top molds using a heavy cast iron cap to

seal the top of the ingot and to stop the rimming action [29]. Chemically capped steel is cast in

open-top molds. The capping is accomplished by the addition of Al or ferrosilicon to the top

of the ingot, causing the steel at the top surface to solidify rapidly. The top portion of the

ingot is cropped and discarded.

1.3.2 QUALITY DESCRIPTORS AND CLASSIFICATIONS

Quality descriptors are names applied to various steel products to indicate that a particular

product possesses certain characteristics that make it especially well suited for specific applica-

tions or fabrication processes. The quality designations and descriptors for various carbon steel

products and alloy steel plates are listed in Table 1.1. Forging quality and cold extrusion quality

descriptors for carbon steels are self-explanatory. However, others are not explicit; for example,

merchant quality hot-rolled carbon steel bars are made for noncritical applications requiring

modest strength and mild bending or forming but not requiring forging or heat-treating oper-

ations. The quality classification for one steel commodity is not necessarily extended to subse-

quent productsmade from the same commodity; for example, standard quality cold-finished bars

are produced from special quality hot-rolled carbon steel bars. Alloy steel plate qualities are

described by structural, drawing, cold working, pressure vessel, and aircraft qualities [27].

The various physical and mechanical characteristics indicated by a quality descriptor result

from the combined effects of several factors such as (1) the degree of internal soundness, (2) the

relative uniformity of chemical composition, (3) the number, size, and distribution of non-

metallic inclusions, (4) the relative freedom from harmful surface imperfections, (5) extensive

testing during manufacture, (6) the size of the discard cropped from the ingot, and (7) hard-

enability requirements. Control of these factors during manufacture is essential to achieve mill

products with the desired characteristics. The degree of control over these and other related

factors is another segment of information conveyed by the quality descriptor.

Some, but not all, of the basic quality descriptors may be modified by one or more

additional requirements as may be appropriate, namely macroetch test, special discard,

restricted chemical composition, maximum incidental (residual) alloying elements, austenitic

grain size, and special hardenability. These limitations could be applied forging quality alloy

steel bars but not to merchant quality bars.

Understanding the various quality descriptors is difficult because most of the prerequisites

for qualifying steel for a specific descriptor are subjective. Only limitations on chemical

composition ranges, residual alloying elements, nonmetallic inclusion count, austenitic grain

size, and special hardenability are quantifiable. The subjective evaluation of the other attributes

depends on the experience and the skill of the individuals who make the evaluation. Although

the use of these subjective quality descriptors might appear impractical and imprecise, steel

products made to meet the requirements of a specific quality descriptor can be relied upon to

have those characteristics necessary for that product to be used in the suggested application or

fabrication operation [6].



TABLE 1.1Quality Descriptionsa of Carbon and Alloy Steels

Carbon Steels Alloy Steels

Semifinished for forging Hot-rolled sheets Mill products Alloy steel plates

Forging quality

Special hardenability

Special internal

soundness

Nonmetallic inclusion

requirement

Special surface

Carbon steel structural

sections

Structural quality

Carbon steel plates

Regular quality

Structural quality

Cold-drawing quality

Cold-pressing quality

Cold-flanging quality

Forging quality

Pressure vessel quality

Hot-rolled carbon steel

bars

Merchant quality

Special quality


Special internal

soundness


requirement

Special surface

Scrapless nut quality

Axle shaft quality

Cold extrusion quality

Cold-heading and cold-

forging quality

Cold-finished carbon steel

bars

Standard quality


Special internal

soundness


requirement

Special surface

Cold-heading and cold-

forging quality

Cold extrusion quality

Commercial quality

Drawing quality

Drawing quality special

killed

Structural quality

Cold-rolled sheets

Commercial quality

Drawing quality


killed

Structural quality

Porcelain enameling sheets

Commercial quality

Drawing quality


killed

Long terne sheets

Commercial quality

Drawing quality


killed

Structural quality

Galvanized sheets

Commercial quality

Drawing quality


killed

Lock-forming quality

Electrolytic zinc coated

sheets

Commercial quality

Drawing quality


killed

Structural quality

Hot-rolled strip

Commercial quality

Drawing quality


killed

Structural quality

Cold-rolled strip

Specific quality

descriptions are not

Specific quality

descriptions are not

applicable to tin mill

products

Carbon steel wire

Industrial quality wire

Cold extrusion wires

Heading, forging, and

roll-threading wires

Mechanical spring wires

Upholstery spring

construction wires

Welding wire

Carbon steel flut wire

Stitching wire

Stapling wire

Carbon steel pipe

Structural tubing

Line pipe

Oil country tubular goods

Steel specialty tubular

products

Pressure tubing

Mechanical tubing

Aircraft tubing

Hot-rolled carbon steel

wire rods

Industrial quality

Rods for

manufacture of

wire intended for

electric welded chain

Rods for heading,

forging, and roll-

threading wire

Rods for lock washer

wire

Rods for scrapless nut

wire

Rods for upholstery

spring wire

Rods for welding wire

Drawing quality

Pressure vessel quality

Structural quality

Aircraft physical quality

Hot-rolled alloy steel bars

Regular quality

Aircraft quality or steel

subject to magnetic

particle inspection

Axle shaft quality

Bearing quality

Cold-heading quality

Special cold-heading

quality

Rifle barrel quality,

gun quality, shell or

A.P. shot quality

Alloy steel wire

Aircraft quality

Bearing quality

Special surface quality

Cold-finished alloy steel

bars

Regular quality

Aircraft quality or

steel subject to

magnetic particle

inspection

Axle shaft quality

Bearing shaft quality

Cold-heading quality

Special cold-heading

quality

Rifle barrel quality,

gun quality, shell or

A.P. shot quality

Line pipe

Oil country tubular goods

Steel specialty tubular

goods

Pressure tubing

Mechanical tubing

Stainless and heat-

resisting pipe,

pressure



1.3.3 CLASSIFICATION OF STEEL BASED ON CHEMICAL COMPOSITION

1.3.3.1 Carbon and CarbonManganese Steels

In addition to carbon, plain carbon steels contain the following other elements: Mn up to

1.65%, S up to 0.05%, P up to 0.04%, Si up to 0.60%, and Cu up to 0.60%. The effects of each

of these elements in plain carbon steels have been summarized in Section 1.2.

Carbon steel can be classified according to various deoxidation processes (see Section 1.3.1).

Deoxidation practice and steelmaking process will have an effect on the characteristics and

properties of the steel (see Section 1.2). However, variations in C content have the greatest effect

on mechanical properties, with C additions leading to increased hardness and strength. As such,

carbon steels are generally grouped according to their C content. In general, carbon steels contain

up to 2% total alloying elements and can be subdivided into low-carbon, medium-carbon, high-

carbon, and ultrahigh-carbon (UHC) steels; each of these designations is discussed below.

As a group, carbon steels constitute the most frequently used steel. Table 1.2 lists various

grades of standard carbon and low-alloy steels with the Society of Automotive Engineers and

American Iron and Steel Institute (SAE-AISI) designations. Table 1.3 shows some represen-

tative standard carbon steel compositions with SAE-AISI and the corresponding Unified

Numbering System (UNS) designations [6,8,30].

Low-carbon steels contain up to 0.25% C. The largest category of this class is flat-rolled

products (sheet or strip), usually in the cold-rolled or subcritical annealed condition and

usually with final temper-rolling treatment. The carbon content for high formability and high

drawability steels is very low (

TA

BLE

1.2

SAE-

AIS

ID

esig

nat

ion

Syst

emfo

rC

arbon

and

Low

-Alloy

Stee

ls

Num

e ra l

sa n

d

Dig

its

Ty p

eof

S te e

la n

dN

om

ina l

Alloy

Conte

nt

(%)

Num

e ra l

sa n

d

Dig

its

Ty p

eof

S te e

la n

dN

om

ina l

All

oy

Conte

nt

(%)

Num

e ra l

sa n

dD

igit

s

Ty p

eof

S te e

la n

dN

om

ina l

Alloy

Conte

nt

(%)

Car b

on

s te e

lsN

icke l

c h

r om

ium

m

oly

bde n

um

s te e

lsC

hr o

miu

m(b

e ar ing)s t

e els

10xxa

. ... .

.. .

.Pla

inca

rbon

(Mn

1.0

0m

ax)

11xx

. ... .

.. .

.R

esulfurize

d

12xx

. ... .

.. .

.R

esulfurize

dand

rephosp

horize

d

15xx

. ... .

.. .

.Pla

inca

rbon

(max

Mn

range:

1.0

01.6

5)

Manganes

est

eels

13xx

. ... .

.. .

.M

n1.7

5

Nic

kel

stee

ls

23xx

.....

...

.N

i3.5

0

25xx

.....

...

.N

i5.0

0

Nic

kel

ch

rom

ium

stee

ls

31xx

.....

...

.N

i1.2

5;C

r0.6

5and

0.8

0

32xx

.....

...

.N

i1.7

5;C

r1.0

7

33xx

.....

...

.N

i3.5

0;C

r1.5

0and

1.5

7

34xx

.....

...

.N

i3.0

0;C

r0.7

7

Moly

bden

um

stee

ls

40xx

.....

...

.M

o0.2

0and

0.2

5

44xx

.....

...

.M

o0.4

0and

0.5

2

Chro

miu

mm

oly

bden

um

stee

ls

41xx

.....

...

.C

r0.5

0,0.8

0,and

0.9

5;M

o0.1

2,0.2

0,

0.2

5,and

0.3

0

43xx

. ... .

.. .

.N

i1.8

2;C

r0.5

0and

0.8

0;

Mo

0.2

5

43BV

xx

Ni1.8

2;C

r0.5

0;M

o0.1

2and

0.2

5;V

0.0

3m

in

47xx

. ... .

.. .

.N

i1.0

5;C

r0.4

5;M

o0.2

0and

0.3

5

81xx

. ... .

.. .

.N

i0.3

0;C

r0.4

0;M

o0.1

2

86xx

.....

...

.N

i0.5

5;C

r0.5

0;M

o0.2

0

87xx

.....

...

.N

i0.5

5;C

r0.5

0;M

o0.2

5

88xx

.....

...

.N

i0.5

5;C

r0.5

0;M

o0.3

5

93xx

.....

...

.N

i3.2

5;C

r1.2

0;M

o0.1

2

94xx

.....

...

.N

i0.4

5;C

r0.4

0;M

o0.1

2

97xx

.....

...

.N

i0.5

5;C

r0.2

0;M

o0.2

0

98xx

.....

...

.N

i1.0

0;C

r0.8

0;M

o0.2

5

Nic

kel

m

oly

bden

um

stee

ls

46xx

.....

...

.N

i0.8

5and

1.8

2;M

o0.2

0and

0.2

5

48xx

.....

...

.N

i3.5

0;M

o0.2

5

Chro

miu

mst

eels

50xx

.....

...

.C

r0.2

7,0.4

0,0.5

0,and

0.6

5

51xx

.....

...

.C

r0.8

0,0.8

7,0.9

2,0.9

5,1.0

0,and

1.0

5

50xxx. .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

.Cr

0.5

0

51xxx. .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

. Cr

1.0

2m

inC

1.0

0

52xxx. .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

.Cr

1.4

5

Chro

miu

mva

nadiu

mst

eels

61xx

. ... .

.. .

.. .

.. .

.. .

.. .

.. .

.. .

.C

r0.6

0,0.8

0,and

0.9

5;

V0.1

0and

0.1

5m

inT

ungst

ench

rom

ium

stee

l

72xx

.....

...

...

...

...

...

...

...

.W

1.7

5;C

r0.7

5

Silic

onm

anganes

est

eels

92xx

.....

...

...

...

...

...

...

...

.Si1.4

0and

2.0

0;M

n

0.6

5,0.8

2,and

0.8

5;

Cr

0and

0.6

5H

igh-s

tren

gth

low

-alloy

stee

ls

9xx

.....

...

...

...

...

...

...

...

.V

arious

SA

Egra

des

Boro

nst

eels

xxB

xx

.....

...

...

...

...

...

...

...

.Bden

ote

sboro

nst

eel

Lea

ded

stee

ls

xxL

xx

.....

...

...

...

...

...

...

...

.Lden

ote

sle

aded

stee

l

aT

he

xx

inth

ela

sttw

odig

its

ofth

ese

des

ignations

indic

ate

sth

atth

eca

rbon

conte

nt(in

hundre

dth

sofa

per

cent)

isto

be

inse

rted

.

Sourc

e:Fro

mC

ourt

esy

ofA

SM

Inte

rnational,

Mate

rials

Park

,O

H.W

ith

per

mission.

)



TABLE 1.3Standard Carbon Steel Compositions with SAE-AISI and Corresponding UNS Designations

Plain Carbon Steel (Nonresulfurized, 1.0% Mn Max)a

UNS SAE-AISICast or Heat Chemical Ranges and Limits (%)a

Number Number C Mn P max S max

G10060 1006 0.08 max 0.45 max 0.040 0.050

G10080 1008 0.10 max 0.50 max 0.040 0.050

G10090 1009 0.15 max 0.60 max 0.040 0.050

G10100 1010 0.080.13 0.300.60 0.040 0.050

G10120 1012 0.100.15 0.300.60 0.040 0.050

G10150 1015 0.120.18 0.300.60 0.040 0.050

G10160 1016 0.120.18 0.600.90 0.040 0.050

G10170 1017 0.140.20 0.300.60 0.040 0.050

G10180 1018 0.140.20 0.600.90 0.040 0.050

G10190 1019 0.140.20 0.701.00 0.040 0.050

G10200 1020 0.170.23 0.300.60 0.040 0.050

G10210 1021 0.170.23 0.600.90 0.040 0.050

G10220 1022 0.170.23 0.701.00 0.040 0.050

G10230 1023 0.190.25 0.300.60 0.040 0.050

G10250 1025 0.220.28 0.300.60 0.040 0.050

G10260 1026 0.220.28 0.600.90 0.040 0.050

G10300 1030 0.270.34 0.600.90 0.040 0.050

G10330 1033 0.290.36 0.701.00 0.040 0.050

G10350 1035 0.310.38 0.600.90 0.040 0.050

G10370 1037 0.310.38 0.701.00 0.040 0.050

G10380 1038 0.340.42 0.600.90 0.040 0.050

G10390 1039 0.360.44 0.701.00 0.040 0.050

G10400 1040 0.360.44 0.600.90 0.040 0.050

G10420 1042 0.390.47 0.600.90 0.040 0.050

G10430 1043 0.390.47 0.701.00 0.040 0.050

G10450 1045 0.420.50 0.600.90 0.040 0.050

G10490 1049 0.450.53 0.600.90 0.040 0.050

G10500 1050 0.470.55 0.600.90 0.040 0.050

G10550 1055 0.520.60 0.600.90 0.040 0.050

G10600 1060 0.550.66 0.600.90 0.040 0.050

G10640 1064 0.590.70 0.500.80 0.040 0.050

G10650 1065 0.590.70 0.600.90 0.040 0.050

G10700 1070 0.650.76 0.600.90 0.040 0.050

G10740 1074 0.690.80 0.500.80 0.040 0.050

G10750 1075 0.690.80 0.400.70 0.040 0.050

G10780 1078 0.720.86 0.300.60 0.040 0.050

G10800 1080 0.740.88 0.600.90 0.040 0.050

G10840 1084 0.800.94 0.600.90 0.040 0.050

G10850 1085 0.800.94 0.701.00 0.040 0.050

G10860 1086 0.800.94 0.300.50 0.040 0.050

G10900 1090 0.840.98 0.600.90 0.040 0.050

G10950 1095 0.901.04 0.300.50 0.040 0.050

Continued



TABLE 1.3 (Continued)Standard Carbon Steel Compositions with SAE-AISI and Corresponding UNS Designations

Free-Cutting (Resulfurized) Carbon Steel Compositionsa

UNS SAE-AISICast or Heat Chemical Ranges and Limits (%)

Number Number C Mn P max S

G11080 1108 0.080.13 0.500.80 0.040 0.080.13

G11100 1110 0.080.13 0.300.60 0.040 0.080.13

G11170 1117 0.140.20 1.001.30 0.040 0.080.13

G11180 1118 0.140.20 1.301.60 0.040 0.080.13

G11370 1137 0.320.39 1.351.65 0.040 0.080.13

G11390 1139 0.350.43 1.351.65 0.040 0.130.20

G11400 1140 0.370.44 0.701.00 0.040 0.080.13

G11410 1141 0.370.45 1.351.65 0.040 0.080.13

G11440 1144 0.400.48 1.351.65 0.040 0.240.33

G11460 1146 0.420.49 0.701.00 0.040 0.080.13

G11S10 1151 0.480.55 0.701.00 0.040 0.080.13

Standard Resulfurized and Rephosphorized Carbon Steelsa

UNS SAE-AISICast or Heat Chemical Ranges and Limits, %(a)

Number Number C max Mn P S Pb

Gl2110 1211 . . . . . . . . . 0.13 0.600.90 0.070.12 0.100.15

G12120 1212 . . . . . . . . . 0.13 0.701.00 0.070.12 0.160.23

G12130 1213 . . . . . . . . . 0.13 0.701.00 0.070.12 0.240.33

G12150 1215 . . . . . . . . . 0.09 0.751.05 0.040.09 0.260.35

G12144 12L14b . . . . . . . . . 0.15 0.851.15 0.040.09 0.260.35 0.150.35

Standard Nonresulfurized Carbon Steels (Over 1.0% Manganese)

UNS SAE-AISICast or Heat Chemical Ranges and Limits, %

Number Number C Mn P max S max

G15130 1513 . . . . . . . . . . . . . . . . . . 0.100.16 1.101.40 0.040 0.050

G15220 1522 . . . . . . . . . . . . . . . . . . 0.180.24 1.101.40 0.040 0.050

G15240 1524 . . . . . . . . . . . . . . . . . . 0.190.25 1.351.65 0.040 0.050

G15260 1526 . . . . . . . . . . . . . . . . . . 0.220.29 1.101.40 0.040 0.050

G15270 1527 . . . . . . . . . . . . . . . . . . 0.220.29 1.201.50 0.040 0.050

G15360 1536 . . . . . . . . . . . . . . . . . . 0.300.37 1.201.50 0.040 0.050

G15410 1541 . . . . . . . . . . . . . . . . . . 0.360.44 1.351.65 0.040 0.050

G15480 1548 . . . . . . . . . . . . . . . . . . 0.440.52 1.101.40 0.040 0.050

G15510 1551 . . . . . . . . . . . . . . . . . . 0.450.56 0.851.15 0.040 0.050

G15520 1552 . . . . . . . . . . . . . . . . . . 0.470.55 1.201.50 0.040 0.050

G15610 1561 . . . . . . . . . . . . . . . . . . 0.550.65 0.751.05 0.040 0.050

G15660 1566 . . . . . . . . . . . . . . . . . . 0.600.71 0.851.15 0.040 0.050

Applicable to semifinished products for forging, hot-rolled and cold-finished bars, wire rods, and seamless tubing.aIt is not common practice to produce the 12xx series of steels to specified limits for silicon because of its adverse effect

on machinability.bContains 0.150.35% lead; other steels listed here can be produced with similar amounts of lead.

Source: From Numbering System, Chemical Composition, 1993 SAE Handbook, Vol. 1, Materials Society of Automotive

Engineers, Warrendale, PA, pp. 1.011.189.



sections containing ~0.25% C, with up to 1.5% Mn and Al are used if improved toughness is

required. When used for stampings, forgings, seamless tubes, and boilerplate, Al addition should

be avoided. An important type of this category is the low-carbon free-cutting steels containing up

to 0.15% C and up to 1.2% Mn, a minimum of Si and up to 0.35% S with or without 0.30% Pb.

These steels are suited for automotive mass production manufacturing methods [4].

Medium-carbon steels containing 0.300.55% C and 0.601.65% Mn are used where

higher mechanical properties are desired. They are usually hardened and strengthened by

heat treatment or by cold work. Low-carbon and manganese steels in this group find wide

applications for certain types of cold-formed parts that need annealing, normalizing, or

quenching and tempering treatment before use. The higher carbon grades are often cold

drawn to specific mechanical properties for use without heat treatment for some applications.

All of these steels can be used for forgings, and their selection is dependent on the section

size and the mechanical properties needed after heat treatment [8]. These grades, generally

produced as killed steels, are used for a wide range of applications that include automobile

parts for body, engines, suspensions, steering, engine torque converter, and transmission [31].

Some Pb or S additions make them free-cutting grades, whereas Al addition produces grain

refinement and improved toughness. In general, steels containing 0.400.60% C are used as

rails, railway wheels, tires, and axles.

High-carbon steels containing 0.551.00% C and 0.300.90% Mn have more restricted

applications than the medium-carbon steels because of higher production cost and poor

formability (or ductility) and weldability. High-carbon steels find applications in the spring

industry (as light and thicker plat springs, laminated springs, and heavier coiled springs), farm

implement industry (as plow beams, plowshares, scraper blades, discs, mowers, knives, and

harrow teeth), and high-strength wires where improved wear characteristics and higher

strength than those attainable with lower carbon grades are needed.

UHC steels are experimental plain carbon steels with 1.02.1% C (1532 vol% cementite)

[3234]. Optimum superplastic elongation has been found at about 1.6% C content [9]. These

steels have the capability of emerging as important technological materials because they

exhibit superplasticity. The superplastic behavior of these materials is attributed to the

structure consisting of uniform distribution of very fine, spherical, discontinuous particles

(0:1---1:5mm diameter) in a very fine-grained ferrite matrix (0:5---2:0mm diameter) that can bereadily achieved by any of the four thermomechanical treatment routes described elsewhere [4].

1.3.3.2 Low-Alloy Steels

Alloy steels may be defined as those steels that owe their improved properties to the presence

of one or more special elements or to the presence of large proportions of elements such as

Mn and Si than are ordinarily present in carbon steels [26]. Alloy steels contain Mn, Si, or Cu

in quantities greater than the maximum limits (e.g., 1.65% Mn, 0.60% Si, and 0.60% Cu) of

carbon steels, or they contain special ranges or minimums of one or more alloying elements.

However, in some countries Mn, Si, or Cu as an alloy element in low-alloy and alloy steels is

only greater than 1.00% Mn, 0.50% Si, or 0.10% Cu [7].

The alloying elements increase the mechanical and fabrication properties. Broadly, alloy

steels can be divided into (1) low-alloy steels containing less than 5 wt% total noncarbon alloy

addition, (2) medium-alloy steels containing 510 wt% total noncarbon alloy addition, and (3)

high-alloy steels with more than 10wt% total noncarbon alloy addition. Table 1.4 lists some

low-alloy steel compositions with SAE-AISI and corresponding UNS designations.

Low-alloy steels constitute a group of steels that exhibit superior mechanical properties

compared to plain carbon steels as the result of addition of such alloying elements as Ni, Cr,

and Mo. For many low-alloy steels, the main function of the alloying elements is to increase



TA

BLE

1.4

Low

-Alloy

Stee

lC

om

posi

tions

Applica

ble

toB

ille

ts,

Blo

om

s,Sl

abs,

and

Hot-

Rolled

and

Cold

-Fin

ished

Bar

s(S

ligh

tly

Wid

erR

ange

s

of

Com

pos i

tions

Apply

toPla

tes )

UN

S

Num

be r

S AE

Num

be r

Cor r

e spondin

g

AIS

IN

um

be r

L adle

Che m

ica l

Com

pos i

tion

L im

its

(%)a

CM

nP

SSi

Ni

Cr

Mo

V

G13300

1330

1330

0.2

80.3

31.6

01.9

00.0

35

0.0

40

0.1

50.3

5

G13350

1335

1335

0.3

30.3

81.6

01.9

00.0

35

0.0

40

0.1

50.3

5

G13400

1340

1340

0.3

80.4

31.6

01.9

00.0

35

0.0

40

0.1

50.3

5

G13450

1345

1345

0.4

30.4

81.6

01.9

00.0

35

0.0

40

0.1

50.3

5

G40230

4023

4023

0.2

00.2

50.7

00.9

00.0

35

0.0

40

0.1

50.3

5

G40240

4024

4024

0.2

00.2

50.7

00.9

00.0

35

0.0

350.0

50

0.1

50.3

5

0.2

00.3

0

G40270

4027

4027

0.2

50.3

00.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

0

G40280

4028

4028

0.2

50.3

00.7

00.9

00.0

35

0.0

350.0

50

0.1

50.3

5

0.2

00.3

0

G40320

4032

0.3

00.3

50.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

0

G40370

4037

4037

0.3

50.4

00.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

0

G40420

4042

0.4

00.4

50.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

0

G40470

4047

4047

0.4

50.5

00.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

0

G41180

4118

4118

0.1

80.2

30.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.4

00.6

00.0

80.1

5

G41300

4130

4130

0.2

80.3

30.4

00.6

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41350

4135

0.3

30.3

80.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41370

4137

4137

0.3

50.4

00.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41400

4140

4140

0.3

80.4

30.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41420

4142

4142

0.4

00.4

50.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41450

4145

4145

0.4

10.4

80.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41470

4147

4147

0.4

50.5

00.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41500

4150

4150

0.4

80.5

30.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

00.1

50.2

5

G41610

4161

4161

0.5

60.6

40.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

00.2

50.3

5

G43200

4320

4320

0.1

70.2

20.4

50.6

50.0

35

0.0

40

0.1

50.3

51.6

52.0

00.4

00.6

00.2

00.3

0

G43400

4340

4340

0.3

80.4

30.6

00.8

00.0

35

0.0

40

0.1

50.3

51.6

52.0

00.7

00.9

00.2

00.3

0

G43406

E4340

bE

4340

0.3

80.4

30.6

50.8

50.0

25

0.0

25

0.1

50.3

51.6

52.0

00.7

00.9

00.2

00.3

0

G44220

4422

0.2

00.2

50.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.3

50.4

5

G44270

4427

0.2

40.2

90.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.3

50.4

5



G46150

4615

4615

0.1

30.1

80.4

50.6

50.0

35

0.0

40

0.1

50.2

51.6

52.0

0

0.2

00.3

0

G46170

4617

0.1

50.2

00.4

50.6

50.0

35

0.0

40

0.1

50.3

51.6

52.0

0

0.2

00.3

0

G46200

4620

4620

0.1

70.2

20.4

50.6

50.0

35

0.0

40

0.1

50.3

51.6

52.0

0

0.2

00.3

0

G46260

4626

4626

0.2

40.2

90.4

50.6

50.0

35

0.0

40

max

0.1

50.3

50.7

01.0

0

0.1

50.2

5

G47180

4718

4718

0.1

60.2

10.7

00.9

0

0.9

01.2

00.3

50.5

50.3

00.4

0

G47200

4720

4720

0.1

70.2

20.5

00.7

00.0

35

0.0

40

0.1

50.3

50.9

01.2

00.3

50.5

50.1

50.2

5

G48150

4815

4815

0.1

30.1

80.4

00.6

00.0

35

0.0

40

0.1

50.3

53.2

53.7

5

0.2

00.3

0

G48170

4817

4817

0.1

50.2

00.4

00.6

00.0

35

0.0

40

0.1

50.3

53.2

53.7

5

0.2

00.3

0

G48200

4820

4820

0.1

80.2

30.5

00.7

00.0

35

0.0

40

0.1

50.3

53.2

33.7

5

0.2

00.3

0

G50401

50B

40c

0.3

80.4

30.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.4

00.6

0

G50441

50B

44c

50B44

0.4

30.4

80.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.4

00.6

0

G50460

5O

46

0.4

30.4

80.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

5

G50461

50B

46c

50B46

0.4

40.4

90.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.2

00.3

5

G50501

50B

50c

50B50

0.4

80.5

30.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.4

00.6

0

G50600

5060

0.5

60.6

40.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.4

00.6

0

G50601

50B

60c

50B60

0.5

60.6

40.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.4

00.6

0

G51150

5115

0.1

30.1

80.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G51170

5117

5117

0.1

50.2

00.7

01.9

00.0

40

0.0

40

0.1

50.3

5

0.7

00.9

0

G51200

5120

5120

0.1

70.2

20.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G51300

5130

5130

0.2

80.3

30.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

0

G51320

5132

5132

0.3

00.3

50.6

00.8

00.0

35

0.0

40

0.1

50.3

5

0.7

51.0

0

G51350

5135

5135

0.3

30.3

80.6

00.8

00.0

35

0.0

40

0.1

53.3

5

0.8

01.0

5

G51400

5140

5140

0.3

80.4

30.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G51470

5147

5147

0.4

60.5

10.7

00.9

50.0

35

0.0

40

0.1

50.3

5

0.8

51.1

5

G51500

5150

5150

0.4

80.5

30.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G51550

5155

5155

0.5

10.5

90.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G51600

5160

5160

0.5

60.6

40.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G51601

51B

60c

51B60

0.5

60.6

40.7

51.0

00.0

35

0.0

40

0.1

50.3

5

0.7

00.9

0

G50986

50100b

0.9

81.1

00.2

50.4

50.0

25

0.0

25

0.1

50.3

5

0.4

00.6

0

G51986

51100b

E51100

0.9

81.1

00.2

50.4

50.0

25

0.0

25

0.1

50.3

5

0.9

01.1

5

G52986

52100b

E52100

0.9

81.1

00.2

50.4

50.0

25

0.0

25

0.1

50.3

5

1.3

01.6

0

Continued



TA

BLE

1.4

(Conti

nued

)Lo

w-A

lloy

Stee

lC

om

posi

tio

ns

Applica

ble

toB

ille

ts,

Blo

om

s,Sl

abs,

and

Hot-

Rolled

and

Cold

-Fin

ished

Bar

s(S

ligh

tly

Wid

erR

ange

s

of

Com

posi

tio

ns

Apply

toPla

tes)

UN

S

Num

ber

SAE

Num

ber

Corr

espondin

g

AIS

IN

um

ber

Ladle

Chem

ical

Com

posi

tion

Lim

its

(%)a

CM

nP

SSi

Ni

Cr

Mo

V

G61180

6118

6118

0.1

60.2

10.5

00.7

00.0

35

0.0

40

0.1

50.3

5

0.5

00.7

0

0.1

00.1

5

G61500

6150

6150

0.4

80.5

30.7

00.9

00.0

35

0.0

40

0.1

50.3

5

0.8

01.1

0

0.1

5m

in

G81150

8115

8115

0.1

30.1

80.7

00.9

00.0

35

0.0

40

0.1

50.3

50.2

00.4

00.3

00.5

00.0

80.1

5

G81451

81B

45c

81B

45

0.4

30.4

80.7

51.0

00.0

35

0.0

40

0.1

50.3

50.2

00.4

00.3

50.5

50.0

80.1

5

G86150

8615

8615

0.1

30.1

80.7

00.9

00.0

35

0.0

40

0.1

50.3

50.4

00.7

00.4

00.6

00.1

50.2

5

G86170

8617

8617

0.1

50.2

00.7

00.9

00.0

35

0.0

40

0.1

50.3

50.4

00.7

00.4

00.6

00.1

50.2

5

G86200

8620

8620

0.1

80.2

30.7

00.9

00.0

35

0.0

40

0.1

50.3

50.4

00.7

00.4

00.6

00.1

50.2

5

G86220

8622

8622

0.2

00.2

50.7

00.9

00.0

35

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