steel heat treatment metallurgy and technologies 2nd ed g totten crc 2007 ww potx

ß 2006 by Taylor & Francis Group, LLC.
ß 2006 by Taylor & Francis Group, LLC.
ß 2006 by Taylor & Francis Group, LLC.
ß 2006 by Taylor & Francis Group, LLC.
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-Treat ed Components (New Chapter)
Chapter 11. Tool Steels (New Chapter)
Chapter 12. Stainless Steel Heat Treatm ent (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
ß 2006 by Taylor & Francis Group, LLC.
ß 2006 by Taylor & Francis Group, LLC.
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,andSurface Modification
and Mechanisms (all titles of CRC Press), as well as the author or coauthor of over 400
technical papers, patents, and books on lubri cation, 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.
ß 2006 by Taylor & Francis Group, LLC.
ß 2006 by Taylor & Francis Group, LLC.
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
Boz
ˇ
idar Lis
ˇ
c
ˇ
ic
´
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
ß 2006 by Taylor & Francis Group, LLC.
ß 2006 by Taylor & Francis Group, LLC.
Contents
Chapter 1 Steel Nomenclature
Anil Kumar Sinha, Chengjian Wu, and Guoquan Liu
Chapter 2 Classification and Mechan isms of Steel Transfor mation
S.S. Babu
Chapter 3 Fundamental Concepts in Steel Heat Treatment
Alexey V. Sverdlin and Arnold R. Ness
Chapter 4 Effects of Alloying Elements on the Heat Treatment of Steel
Alexey V. Sverdlin and Arnold R. Ness
Chapter 5 Hardenability
Boz
ˇ
idar Lis
ˇ
c
ˇ
ic
´
Chapter 6 Steel Heat Treatment
Boz
ˇ

idar Lis
ˇ
c
ˇ
ic
´
Chapter 7 Heat Treatment with Gaseous Atmospheres
Johann Grosch
Chapter 8 Nitriding Techniques, Ferritic Nitrocarburizing, and
Austenitic Nitrocarburizing Techniques and Methods
David Pye
Chapter 9 Quenching and Quenching Technology
Hans M. Tensi, Anton Stich, and George E. Totten
Chapter 10 Distortion of Heat-Treated Components
Michiharu Narazaki and George E. Totten
Chapter 11 Tool Steels
Elhachmi Essadiqi
Chapter 12 Stainless Steel Heat Treatment
Angelo Fernando Padilha, Ronald Lesley Plaut, and Paulo Rangel Rios
ß 2006 by Taylor & Francis Group, LLC.
Chapter 13 Heat Treatment of Powder Metallurgy Steel Components
Joseph W. Newkirk and Sanjay N. Thakur
Appendices
Appendix 1 Com mon Conversion Constants
Appendix 2 Temperature Conversion Table
Appendix 3 Vol ume Conversion Table
Appendix 4 Hardness Conversion Tables: Hardened Steel and Hard Alloys
Appendix 5 Recommended MIL 6875 Specification Steel Heat
Treatment Conditions
Appendix 6 Col ors of Hardening and Tempering Heats

Appendix 7 Weight Tables for Steel Bars
ß 2006 by Taylor & Francis Group, LLC.
1
Steel Nomenclature
Anil 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 Carbon–Manganese 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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1.3.3.6 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 Chem ical 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 iron–carbon phase diagram [1–3], all binary Fe–C 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 Earth’s crust, (2) the high melting temperature of iron
(15348C), (3) a range of mechanical properties, such as moderate (200–300 MPa) yield
strength with excellent ductility to in excess of 1400 MPa yield stress with fracture toughness
up to 100 MPa m
À2
, 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 alloy ing elements and impurities that must be associated with austenite, ferrite,
and cementite. The combined effects of alloying elements and heat treatment produc e 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 2.11 wt% [1] or 2.06 wt% [2], while it is

calculated thermodynamically as 2.14 wt% [3].
ß 2006 by Taylor & Francis Group, LLC.
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, ha s been
revie wed extens ively in Chapt er 2 of this handb ook an d elsewh ere in the literat ure [4,5 ,8–12].
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 stabili zers)
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 lis ted 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 0.15–0.30% 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 dislo cations). Carbide-
forming elements may interact with carbon and form alloy carbide s. 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 virtuall y 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.
ß 2006 by Taylor & Francis Group, LLC.
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 distortion
during 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 Cr–Ni 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, Mn–Si, Cr–Ni, and Cr–Mn
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 Cr–Ni 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 0.08–0.33% 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
ß 2006 by Taylor & Francis Group, LLC.
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 react ion. Aluminum is also used in maraging steels. Alum inum 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 and
stabilize 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)
3
C forms. If the Cr/C ratio rises, chromium carbides (Cr,Fe)
7
C
3
or (Cr,Fe)

23
C
6
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 chromium–iron 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, Ni
is an austeni te-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 FATT
50%
(8C),
even at the subzero temperatures [20]. Nickel raises the corrosion resistance of Cr–Ni
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 harden ing during the tempering of quenched steels and improves the
creep strength of low-alloy steels at elevated temperatures.
ß 2006 by Taylor & Francis Group, LLC.
The addition of Mo produces fine-grained steels, increases hardenability, and improves
fatigue strength. Alloy steels containing 0.20–0.40% 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 Cr–Ni austenitic
stainless steels. High Mo co ntents reduce the stainless steel’s 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 impar ts 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 qua lity, 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 an d 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 Cr–Ni 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].
ß 2006 by Taylor & Francis Group, LLC.
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 Cr–Mo alloy steels. Cobalt raises the marten-
sitic transformation temperature of M
s
(8C) and decreases the amount of retained austenite in
alloy 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 ope rations. 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 H
2
SO
4
and HCl and stress corrosion [5,15].
1.2.18 BORON
Boron (B), in very small amounts (0.0005–0.0035%), 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.
ß 2006 by Taylor & Francis Group, LLC.
1.2.19 Z IRCONIUM
Zircon ium (Zr) is add ed to killed HSLA steel s to obtain impr ovement in inclus ion charac-
teristi cs, pa rticular ly su lfide inclus ions, wher e modif ications of inclus ion shap e impro ve
duc tility in trans verse be nding. It increa ses the life of he at-cond ucting mate rials. It is also a
strong carbide form er and produ ces a contrac ted austenite phase field [5,15].
1.2.20 L EAD
Lea d (Pb) is sometime s added (in the range of 0.2–0.5 %) to carbon and alloy steels through
mechan ical disper sion during teem ing to impr ove machin ability.
1.2.21 T IN
Tin (Sn ) in relative ly small amounts is harmful to steels. It ha s a very strong tenden cy to segreg ate
at grain bounda ries and induces tempe r embritt lement in alloy steels. It has a detri mental effect
on the surfa ce qua lity of con tinuous cast billets co ntaining small amounts of Cu [24]. Small
amoun ts of Sn a nd Cu also de crease the hot duc tility of steels in the austenite þ ferrite region [25].
1.2.22 A NTIMONY
Antimo ny (Sb) has a strong tendency to segreg ate during the freez ing pro cess, and has a
detri mental effect on the surfa ce qua lity of con tinuous cast bill ets. It also has a very strong
tenden cy to segreg ate at grain bounda ries an d cause tempe r embri ttlement in alloy steels.
1.2.23 C ALCIUM
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
Steel s can be class ified by different systems de pending on [4,6 ,8]:
1. Comp ositions, suc h as carbon (or nonalloy ), low -alloy, an d alloy steels
2. Manufact uring methods , such as convert er, electric furnace , or electrosl ag remelti ng
methods
3. Applicati on or main charact eristic, such as structural , tool, stainles s steel, or he at-
resistant steels

4. Finishin g 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. Micros tructure, such as ferr itic, pearli tic, mart ensitic, and austeniti c (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 forgi ng 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.
ß 2006 by Taylor & Francis Group, LLC.
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 by
commercial name
or application
Ferrous alloys
Steel
Plain carbon
steel
Low-carbon

steel
(<0.2% C)
Medium-carbon
steel
(0.2
−5% C)
High-carbon
steel
(>0.5% C)
Low- and medium-
alloy steel
≤10% alloying
elements
High-alloy
steel
>10% alloying
elements
Corrosion
resistant
Heat
resistant
Wear
resistant
Duplex
structure
Austenitic−
ferritic
Precipitation
hardened
Austenitic

Bainitic
Martensitic
Pearlitic
Ferritic
−pearlitic
Classification
by structure
Alloys without
eutectic
(<2% C on Fe
−C
diagram)
Ferritic
FIGURE 1.1 Classification of steels. (Courtesy of D.M. Stefanescu, University of Alabama, Tuscaloosa,
AL. Slightly modified by the present authors.)
ß 2006 by Taylor & Francis Group, LLC.
low-alloy steels, and many carbon steels are usually killed. The continuous casting billets are also
killed. The essential quality criterion is soundness [26–28]. 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 wel l-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 0.15–0.30%. 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 segreg ation 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.
12345678
Killed Semikilled Capped Rimmed
FIGURE 1.2 Eight typical conditions of commercial steel ingots, cast in identical bottle-top molds, in
relation 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.)
ß 2006 by Taylor & Francis Group, LLC.
1.3.1 .4 Cappe d Steels
Capped steel is a type of steel wi th charact eristic s sim ilar to those of a rimmed steel but to a
degree inter media te between that of rim med and semik illed steel s. Less deoxidi zer is used to
produ ce a capped ingot than to prod uce a semik illed ingot [29]. This induces a control led
rimming acti on when the ingot is cast. The gas entrappe d during soli dificatio n is ex cess of that

requir ed to countera ct normal shrinka ge, resul ting in a tendency for the steel to rise in the mold.
Capping is a variation of rimmed steel practi ce. The capping operati on confine s the time
of gas evo lution and preven ts the formati on of a n e xcessive number of gas vo ids within the
ingot. The capp ed ingo t process is us ually applie d to steels wi th carbon con tents greater than
0.15% that are used for sheet, strip, tin plate , skelp, wi re, and bars.
Mechanica lly capped steel is pour ed into bottle-t op molds using a he avy cast iron cap to
seal the top of the ingot and to stop the rim ming actio n [29] . Chemical ly capped steel is cast in
open -top molds . The cap ping is a ccomplished by the a ddition of Al or ferr osilicon to the top
of the ingot, causing the steel at the top surfac e to solidify rapidl y. The top portion of the
ingot is cropped and discar ded.
1.3.2 QUALITY DESCRIPTORS AND C LASSIFICATIONS
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 products made 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].
ß 2006 by Taylor & Francis Group, LLC.
TABLE 1.1
Quality Descriptions
a
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 hardenability
Special internal
soundness
Nonmetallic inclusion
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 hardenability
Special internal
soundness

Nonmetallic inclusion
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
Drawing quality special
killed
Structural quality
Porcelain enameling sheets
Commercial quality
Drawing quality
Drawing quality special
killed
Long terne sheets
Commercial quality
Drawing quality
Drawing quality special
killed
Structural quality
Galvanized sheets
Commercial quality

Drawing quality
Drawing quality special
killed
Lock-forming quality
Electrolytic zinc coated
sheets
Commercial quality
Drawing quality
Drawing quality special
killed
Structural quality
Hot-rolled strip
Commercial quality
Drawing quality
Drawing quality special
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
ß 2006 by Taylor & Francis Group, LLC.
1.3.3 C LASSIFICATION OF S TEEL B ASED ON C HEMICAL C OMPOSITION
1.3.3 .1 Car bon and Carb on–Mangane se Steels
In addition to carb on, plain carbon steels co ntain the foll owing other elem ents: 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 effe cts of each
of these elem ents in plain carbo n steels ha ve be en summ arized in Sectio n 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 , carb on steels con stitute the most frequent ly used steel. Table 1.2 lists various
grades of standar d carbo n and low-al loy steel s wi th the Societ y of Autom otive Engi neers an d
Ame rican Iron an d Steel Insti tute (SAE-AI SI) designa tions . Table 1 .3 shows some repres en-
tative standar d carbon steel comp ositions with SAE-AISI and the corres pondin g Un ified
Number ing System (UN S) designa tions [6,8,30].
Low-carbo n steel s con tain up to 0.25% C. The large st categor y of this class is flat-r olled
produ cts (sheet or strip), usuall y in the cold-r olled or subcri tical annealed conditio n an d
usuall y with final tempe r-rolli ng treatment . The carbo n content for high formab ility an d high
draw ability steels is very low (<0.10% C) wi th up to 0.40% M n. These lowe r carbo n steels are
used in automobi le body pa nels, tin plate s, app liances, a nd wire pr oducts.
The low-car bon steels (0.1 0–0.25 % C) have increa sed strength and hardness an d redu ced
form ability compared to the low est carb on group . They are designa ted as carburi zing or case-
hardening steel s [9]. Selection of these grades for carburizing ap plications depend s on the
nature of the part, the propert ies required , an d the process ing pr actices prefer red. An increa se
of carbon content of the ba se steel resul ts in greater core hardness wi th a given que nch.
How ever, an increa se in Mn increa ses the harden ability of both the core an d the case.
A typica l applic ation for carb urized plain carbon steel is for parts with hard wear-re sistant
surfa ce but without any need for increa sed mechani cal propert ies in the core, e.g., small
shafts, plunges, or highly loaded gearing [8]. Rolled structural steels in the form of plates and
provided in cold-
rolled strip because
this product is largely
produced for specific
and use
tubing, and
mechanical tubing
Aircraft tubing
pipe
a
In the case of certain qualities, P and S are usually finished to lower limits than the specified maximum.

Source: From H. Okamoto, C–Fe, in Binary Alloy Phase Diagrams, 2nd ed., T.B. Massalski, Ed., ASM International,
Materials Park, OH, 1990, pp. 842–848.
TABLE 1.1 (Continued)
Quality Descriptions
a
of Carbon and Alloy Steels
Carbon Steels Alloy Steels
ß 2006 by Taylor & Francis Group, LLC.