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Volume 1 Publication Information and Contributors Properties and Selection: Irons, Steels, and High-Performance Alloys was published in 1990 as Volume 1 of the 10th Edition Metals Handbo

ASM INTERNATIONAL ®

The Materials Information Company

Volume 1 Publication Information and Contributors

Properties and Selection: Irons, Steels, and High-Performance Alloys was published in 1990 as Volume 1 of the 10th Edition Metals Handbook With the second printing (1993), the series title was changed to ASM Handbook The Volume

was prepared under the direction of the ASM International Handbook Committee

Authors and Reviewers

• LAMET UFRGS

• G Aggen Allegheny Ludlum Steel Division Allegheny Ludlum Corporation

• Frank W Akstens Industrial Fasteners Institute

• C Michael Allen Adjelian Allen Rubeli Ltd

• H.S Avery Consultant

• P Babu Caterpillar, Inc

• Alan M Bayer Teledyne Vasco

• Felix Bello The WEFA Group

• S.P Bhat Inland Steel Company

• M Blair Steel Founders' Society of America

• Bruce Boardman Deere and Company Technical Center

• Kurt W Boehm Nucor Steel

• Francis W Boulger Battelle-Columbus Laboratories (retired)

• Greg K Bouse Howmet Corporation

• John L Bowles North American Wire Products Corporation

• J.D Boyd Metallurgical Engineering Department Queen's University

• B.L Bramfitt Bethlehem Steel Corporation

• Richard W Bratt Consultant

• W.D Brentnall Solar Turbines

• C.R Brinkman Oak Ridge National Laboratory

• Edward J Bueche USS/Kobe Steel Company

• Harold Burrier, Jr. The Timken Company

• Anthony Cammarata Mineral Commodities Division U.S Bureau of Mines

• A.P Cantwell LTV Steel Company

• M Carlucci Lorlea Steels

• Harry Charalambu Carr & Donald Associates

• Joseph B Conway Mar-Test Inc

• W Couts Wyman-Gordon Company

• Wil Danesi Garrett Processing Division Allied-Signal Aerospace Company

• John W Davis McDonnell Douglas

• R.J Dawson Deloro Stellite, Inc

• Terry A DeBold Carpenter Technology Corporation

• James Dimitrious Pfauter-Maag Cutting Tools

• Douglas V Doanne Consulting Metallurgist

• Mehmet Doner Allison Gas Turbine Division

• Henry Dormitzer Wyman-Gordon Company

• Allan B Dove Consultant (deceased)

• Don P.J Duchesne Adjelian Allen Rubeli Ltd

• Gary L Erickson Cannon-Muskegon Corporation

• Walter Facer American Spring Wire Company

• Brownell N Ferry LTV Steel Company

• F.B Fletcher Lukens Steel Company

• E.M Foley Deloro Stellite, Inc

• R.D Forrest Division Fonderie Pechinery Electrometallurgie

• James Fox Charter Rolling Division Charter Manufacturing Company, Inc

• Edwin F Frederick Bar, Rod and Wire Division Bethlehem Steel Corporation

• James Gialamas USS/Kobe Steel Company

• Jeffery C Gibeling University of California at Davis

• Wayne Gismondi Union Drawn Steel Co., Ltd

• R.J Glodowski Armco, Inc

• Loren Godfrey Associated Spring Barnes Group, Inc

• Alan T Gorton Atlantic Steel Company

• W.G Granzow Research & Technology Armco, Inc

• David Gray Teledyne CAE

• Malcolm Gray Microalloying International, Inc

• Richard B Gundlach Climax Research Services

• I Gupta Inland Steel Company

• R.I.L Guthrie McGill Metals Processing Center McGill University

• P.C Hagopian Stelco Fastener and Forging Company

• J.M Hambright Inland Bar and Structural Division Inland Steel Company

• K Harris Cannon-Muskegon Corporation

• Hans J Heine Foundry Management & Technology

• W.E Heitmann Inland Steel Company

• T.A HeussLTV Steel Bar Division LTV Steel Company

• Thomas Hill Speedsteel of New Jersey, Inc

• M Hoetzl Surface Combustion, Inc

• Peter B Hopper Milford Products Corporation

• J.P Hrusovsky The Timken Company

• David Hudok Weirton Steel Corporation

• S Ibarra Amoco Corporation

• J.E Indacochea Department of Civil Engineering, Mechanics, and Metallurgy University of Illinois at Chicago

• Asjad Jalil The Morgan Construction Company

• William J Jarae Georgetown Steel Corporation

• Lyle R Jenkins Ductile Iron Society

• J.J Jonas McGill Metals Processing Center McGill University

• Robert S Kaplan U.S Bureau of Mines

• Donald M Keane LaSalle Steel Company

• William S Kirk U.S Bureau of Mines

• S.A Kish LTV Steel Company

• R.L Klueh Metals and Ceramics Division Oak Ridge National Laboratory

• G.J.W Kor The Timken Company

• Charles Kortovich PCC Airfoils

• George Krauss Advanced Steel Processing and Products Research Center Colorado School of Mines

• Eugene R Kuch Gardner Denver Division

• J.A Laverick The Timken Company

• M.J Leap The Timken Company

• P.W Lee The Timken Company

• B.F Leighton Canadian Drawn Steel Company

• R.W Leonard USX Corporation

• R.G Lessard Stelpipe Stelco, Inc

• S Liu Center for Welding and Joining Research Colorado School of Mines

• Carl R Loper, Jr. Materials Science & Engineering Department University of Madison

Wisconsin-• Donald G Lordo Townsend Engineered Products

• R.A Lula Consultant

• W.C Mack Babcock & Wilcox Division McDermott Company

• T.P Madvad USS/Kobe Steel Company

• J.K Mahaney, Jr. LTV Steel Company

• C.W Marshall Battelle Memorial Institute

• G.T Matthews The Timken Company

• Gernant E Maurer Special Metals Corporation

• Joseph McAuliffe Lake Erie Screw Corporation

• Thomas J McCaffrey Carpenter Steel Division Carpenter Technology Corporation

• J McClain Danville Division Wyman-Gordon Company

• T.K McCluhan Elkem Metals Company

• D.B McCutcheon Steltech Technical Services Ltd

• Hal L Miller Nelson Wire Company

• K.L Miller The Timken Company

• Frank Minden Lone Star Steel

• Michael Mitchell Rockwell International

• R.W Monroe Steel Founders' Society of America

• Timothy E Moss Inland Bar and Structural Division Inland Steel Company

• Brian Murkey R.B & W Corporation

• T.E Murphy Inland Bar and Structural Division Inland Steel Company

• Janet Nash American Iron and Steel Institute

• Drew V Nelson Mechanical Engineering Department Stanford University

• G.B Olson Northwestern University

• George H Osteen Chaparral Steel

• J Otter Saginaw Division General Motors Corporation

• D.E Overby Stelco Technical Services Ltd

• John F Papp U.S Bureau of Mines

• Y.J Park Amax Research Company

• D.F Paulonis United Technologies

• Leander F Pease III Powder-Tech Associates, Inc

• Thoni V Philip TVP Inc

• Thomas A PhillipsDepartment of the Interior U.S Bureau of Mines

• K.E Pinnow Crucible Research Center Crucible Materials Corporation

• Arnold Plant Samuel G Keywell Company

• Christopher Plummer The WEFA Group

• J.A Pojeta LTV Steel Company

• R Randall Rariton River Steel

• P Repas U.S.S Technical Center USX Corporation

• M.K Repp The Timken Company

• Richard Rice Battelle Memorial Institute

• William L Roberts Consultant

• G.J Roe Bethlehem Steel Corporation

• Kurt Rohrbach Carpenter Technology Corporation

• A.R Rosenfield Battelle Memorial Institute

• James A Rossow Wyman-Gordon Company

• C.P Royer Exxon Production Research Company

• Mamdouh M Salama Conoco Inc

• Norman L Samways Association of Iron and Steel Engineers

• Gregory D Sander Ring Screw Works

• J.A Schmidt Joseph T Ryerson and Sons, Inc

• Michael Schmidt Carpenter Technology Corporation

• W Schuld Seneca Wire & Manufacturing Company

• R.E Schwer Cannon-Muskegon Corporation

• Kay M Shupe Bliss & Laughlin Steel Company

• V.K Sikka Oak Ridge National Laboratory

• Steve Slavonic Teledyne Columbia-Summerill

• Dale L Smith Argonne National Laboratory

• Richard B Smith Western Steel Division Stanadyne, Inc

• Dennis Smyth The Algoma Steel Corporation Ltd

• G.R Speich Department of Metallurgical Engineering Illinois Institute of Technology

• Thomas Spry Commonwealth Edition

• W Stasko Crucible Materials Corporation Crucible Research Center

• Doru M Stefanescu The University of Alabama

• Joseph R Stephens Lewis Research Center National Aeronautics and Space Administration

• P.A Stine General Electric Company

• N.S Stoloff Rensselaer Polytechnic Institute

• John R Stubbles LTV Steel Company

• D.K Subramanyam Ergenics, Inc

• A.E Swansiger ABC Rail Corporation

• R.W Swindeman Oak Ridge National Laboratory

• N Tepovich Connecticut Steel

• Millicent H Thomas LTV Steel Company

• Geoff Tither Niobium Products Company, Inc

• George F Vander Voort Carpenter Technology Corporation

• Elgin Van Meter Empire-Detroit Steel Division Cyclops Corporation

• Krishna M Vedula Materials Science & Engineering Department Case Western Reserve University

• G.M Waid The Timken Company

• Charles F Walton Consultant

• Lee R Walton Latrobe Steel Company

• Yung-Shih Wang Exxon Production Research Company

• S.D Wasko Allegheny Ludlum Steel Division Allegheny Ludlum Corporation

• J.R Weeks Brookhaven National Laboratory

• Charles V White GMI Engineering and Management Institute

• Alexander D Wilson Lukens Steel Company

• Peter H Wright Chaparral Steel Company

• B Yalamanchili North Star Steel Texas Company

• Z Zimerman Bethlehem Steel Corporation

Foreword

For nearly 70 years the Metals Handbook has been one of the most widely read and respected sources of information on

the subject of metals Launched in 1923 as a single volume, it has remained a durable reference work, with each succeeding edition demonstrating a continuing upward trend in growth, in subject coverage, and in reader acceptance As

we enter the final decade of the 20th century, the ever-quickening pace of modern life has forced an increasing demand

for timely and accurate technical information Such a demand was the impetus for this, the 10th Edition of Metals Handbook

Since the publication of Volume 1 of the 9th Edition in 1978, there have been significant technological advances in the field of metallurgy The goal of the present volume is to document these advances as they pertain to the properties and selection of cast irons, steels, and superalloys A companion volume on properties and selection of nonferrous alloys, special-purpose materials, and pure metals will be published this autumn Projected volumes in the 10th Edition will present expanded coverage on processing and fabrication of metals; testing, inspection, and failure analysis; microstructural analysis and materials characterization; and corrosion and wear phenomena (the latter a subject area new

to the Handbook series)

During the 12 years it took to complete the 17 volumes of the 9th Edition, the high standards for technical reliability and

comprehensiveness for which Metals Handbook is internationally known were retained Through the collective efforts of

the ASM Handbook Committee, the editorial staff of the Handbook, and nearly 200 contributors from industry, research

organizations, government establishments, and educational institutions, Volume 1 of the 10th Edition continues this legacy of excellence

first in the new 10th Edition series of Metals Handbook to present such data

Like the technology it documents, the Metals Handbook is also evolving To be truly effective and valid as a reference

work, each Edition of the Handbook must have its own identity To merely repeat information, or to simply make superficial cosmetic changes, would be self-defeating As such, utmost care and thought were brought to the task of planning the 10th Edition by both the ASM Handbook Committee and the Editorial Staff

To ensure that the 10th Edition continued the tradition of quality associated with the Handbook, it was agreed that it was necessary to:

• Determine which subjects (articles) not included in previous Handbooks needed to be added to the 10th Edition

• Determine which previously published articles needed only to be revised and/or expanded

• Determine which previously published articles needed to be completely rewritten

• Determine which areas needed to be de-emphasized

• Identify and eliminate obsolete data

The next step was to determine how the subject of properties selection should be addressed in the 10th Edition Considering the information explosion that has taken place during the past 30 years, the single-volume approach used for Volume 1 of the 8th Edition (published in 1961) was not considered feasible For the 9th Edition, three separate volumes

on properties and selection were published from 1978 to 1980 This approach, however, was considered somewhat fragmented, particularly in regard to steels: carbon and low-alloy steels were covered in Volume 1, whereas tools steels, austenitic manganese steels, and stainless steels were described in Volume 3 After considering the various options, it was decided that the most logical and user-friendly approach would be to publish two comprehensive volumes on properties and selection In the present volume, emphasis has been placed on cast irons, carbon and low-alloy steels, and high-performance alloys such as stainless steels and superalloys A companion volume on properties and selection of nonferrous alloys and special-purpose materials will follow (see Table 1 for an abbreviated table of contents)

Table 1 Abbreviated table of contents for Volume 2, 10th Edition, Metals Handbook

Specific Metals and Alloys

Wrought Aluminum and Aluminum Alloys

Cast Aluminum Alloys

Aluminum-Lithium Alloys

Aluminum P/M Alloys

Wrought Copper and Copper Alloys

Cast Copper Alloys

Copper P/M Products

Nickel and Nickel Alloys

Beryllium-Copper and Beryllium-Nickel Alloys

Cobalt and Cobalt Alloys

Magnesium and Magnesium Alloys

Tin and Tin Alloys

Zinc and Zinc Alloys

Lead and Lead Alloys

Refractory Metals and Alloys

Wrought Titanium and Titanium Alloys

Cast Titanium Alloys

Titanium P/M Alloys

Zirconium and Hafnium

Uranium and Uranium Alloys

Beryllium

Precious Metals

Rare Earth Metals

Germanium and Germanium Compounds

Gallium and Gallium Compounds

Indium and Bismuth

Special-Purpose Materials

Soft Magnetic Materials

Permanent Magnet Materials

Metallic Glasses

Superconducting Materials

Electrical Resistance Alloys

Electric Contact Materials

Thermocouple Materials

Low Expansion Alloys

Shape-Memory Alloys

Materials For Sliding Bearings

Metal-Matrix Composite Materials

Ordered Intermetallics

Cemented Carbides

Cermets

Superabrasives and Ultrahard Tool Materials

Structural Ceramics

Pure Metals

Preparation and Characterization of Pure Metals

Properties of Pure Metals

Special Engineering Topics

Recycling of Nonferrous Alloys

Toxicity of Metals

Principal Sections

Volume 1 has been organized into seven major sections:

• Cast Irons

• Carbon and Low-Alloy Steels

• Hardenability of Carbon and Low-Alloy Steels

• Fabrication Characteristics of Carbon and Low-Alloy Steels

• Service Characteristics of Carbon and Low-Alloy Steels

• Specialty Steels and Heat-Resistant Alloys

• Special Engineering Topics

Of the 53 articles contained in these sections, 14 are new, 10 were completely rewritten, and the remaining articles have been substantially revised A review of the content of the major sections is given below; highlighted are differences between the present volume and its 9th Edition predecessor Table 2 summarizes the content of the principal sections

Table 2 Summary of contents for Volume 1, 10th Edition, Metals Handbook

articles

Pages Figures (a) Tables (b) References

Carbon and Low-Allow Steels 21 344 298 266 230

Hardenability of Carbon and Low-Alloy Steels 3 122 210 178 28

Fabrication Characteristics of Carbon and Low-Alloy Steels 4 44 56 10 85

Service Characteristics of Carbon and Low-Alloy Steels 6 140 219 22 567

Specialty Steels and Heat-Resistant Alloys 11 252 249 163 358

Special Engineering Topics 2 27 29 11 50

(a) Total number of figure captions; some figures may include more than one illustration

(b) Does not include unnumbered in-text tables or tables that are part of figures

Cast irons are described in six articles The introductory article on "Classification and Basic Metallurgy of Cast Irons"

was completely rewritten for the 10th Edition The article on "Compacted Graphite Iron" is new to the Handbook Both of these contributions were authored by D.M Stefanescu (The University of Alabama), who served as Chairman of Volume

15, Casting, of the 9th Edition The remaining four articles contain new information on materials (for example,

austempered ductile iron) and testing (for example, dynamic tear testing)

Carbon and Low-Alloy Steels Key additions to this section include articles that explain the relationships among

processing (both melt and rolling processes), microstructures, and properties of steels Of particular note is the article by

G Krauss (Colorado School of Mines) on pages 126 to 139 and the various articles on high-strength low-alloy steels Other highlights include an extensive tabular compilation that cross-references SAE-AISI steels to their international counterparts (see the article "Classification and Designation of Steels") and an article on "Bearing Steels" that compares both case-hardened and through-hardened bearing materials

Hardenability of Carbon and Low-Alloy Steels Following articles that introduce H-steels and describe

hardenability concepts, including test procedures to determine the hardening response of steels, a comprehensive collection of hardenability curves is presented Both English and metric hardenability curves are provided for some 86 steels

Fabrication Characteristics Sheet formability, forgeability, machinability, and weldability are described next The

article on bulk formability, which emphasizes recent studies on HSLA forging steels, is new to the Handbook series The material on weldability was completely rewritten and occupies nearly four times the space allotted in the 9th Edition

Service Characteristics The influence of various in-service environments on the properties of steels is one of the

most widely studied subjects in metallurgy Among the topics described in this section are elevated-temperature creep properties, low-temperature fracture toughness, fatigue properties, and impact toughness A new article also describes the deleterious effect of neutron irradiation on alloy and stainless steels Of critical importance to this section, however, is the definitive treatise on "Embrittlement of Steels" written by G.F Vander Voort (Carpenter Technology Corporation) Featuring more than 75 graphs and 372 references, this 48-page article explores the causes and effects of both thermal and environmental degradation on a wide variety of steels Compared with the 9th Edition on the same subject, this represents

a nearly tenfold increase in coverage

Specialty Steels and Heat-Resistant Alloys Eleven articles on wrought, cast, and powder metallurgy materials

for specialty and/or high-performance applications make up this section Alloy development and selection criteria as related to corrosion-resistant and heat-resistant steels and superalloys are well documented More than 100 pages are devoted to stainless steels, while three new articles have been written on superalloys including one on newly developed directionally solidified and single-crystal nickel-base alloys used for aerospace engine applications

Special Engineering Topics The final section examines two subjects that are becoming increasingly important to the

engineering community: (1) the availability and supply of strategic materials, such as chromium and cobalt, used in

stainless steel and superalloy production, and (2) the current efforts to recycle highly alloyed materials Both of these subjects are new to the Handbook series A second article on recycling of nonferrous alloys will be published in Volume 2

of the 10th Edition

Acknowledgments

Successful completion of this Handbook required the cooperation and talents of literally hundreds of professional men and women In terms of the book's technical content, we are indebted to the authors, reviewers, and miscellaneous contributors-some 200 strong-upon whose collective experience and knowledge rests the accuracy and authority of the volume Thanks are also due to the ASM Handbook Committee and its capable Chairman, Dennis D Huffman (The Timken Company) The ideas and suggestions provided by members of the committee proved invaluable during the two years of planning required for the 10th edition Lastly, we would like to acknowledge the efforts of those companies who have worked closely with ASM's editorial and production staff on this and many other Handbook volumes Our thanks go

to Byrd Data Imaging for their tireless efforts in maintaining a demanding typesetting schedule, to Rand McNally & company for the care and quality brought to printing the Handbook, and to Precision Graphics, Don O Tech, Accurate Art, and HaDel Studio for their attention to detail during preparation of Handbook artwork Their combined efforts have resulted in a significant and lasting contribution to the metals industry

The Editors

General Information

Officers and Trustees of ASM INTERNATIONAL (1990-1991)

• Klaus M Zwilsky President and Trustee National Materials Advisory Board National Academy

of Sciences

• Stephen M Copley Vice President and Trustee Illinois Institute of Technology

• Richard K Pitler Immediate Past President and Trustee Allegheny Ludlum Corporation

(retired)

• Edward L Langer Secretary and Managing Director ASM INTERNATIONAL

• Robert D Halverstadt Treasurer AIMe Associates

Trustees

• John V Andrews Teledyne Allvac

• Edward R Burrell Inco Alloys International, Inc

• H Joseph Klein Haynes International, Inc

• Kenneth F Packer Packer Engineering, Inc

• Hans Portisch VDM Technologies Corporation

• William E Quist Boeing Commercial Airplanes

• John G Simon General Motors Corporation

• Charles Yaker Howmet Corporation

• Daniel S Zamborsky Consultant

Members of the ASM Handbook Committee (1990-1991)

• Dennis D Huffman (Chairman 1986-; Member 1983-) The Timken Company

• Roger J Austin (1984-) ABARIS

• Roy G Baggerly (1987-) Kenworth Truck Company

• Robert J Barnhurst (1988-) Noranda Research Centre

• Hans Borstell (1988-) Grumman Aircraft Systems

• Gordon Bourland (1988-) LTV Aerospace and Defense Company

• John F Breedis (1989-) Olin Corporation

• Stephen J Burden (1989-) GTE Valenite

• Craig V Darragh (1989-) The Timken Company

• Gerald P Fritzke (1988-) Metallurgical Associates

• J Ernesto Indacochea (1987-) University of Illinois at Chicago

• John B Lambert (1988-) Fansteel Inc

• James C Leslie (1988-) Advanced Composites Products and Technology

• Eli Levy (1987-) The De Havilland Aircraft Company of Canada

• William L Mankins (1989-) Inco Alloys International, Inc

• Arnold R Marder (1987-) Lehigh University

• John E Masters (1988-) American Cyanamid Company

• David V Neff (1986-) Metaullics Systems

• David LeRoy Olson (1982-1988; 1989-) Colorado School of Mines

• Dean E Orr (1988-) Orr Metallurgical Consulting Service, Inc

• Edwin L Rooy (1989-) Aluminum Company of America

• Kenneth P Young (1988-) AMAX Research & Development

Previous Chairmen of the ASM Handbook Committee

D Wheaton

Conversion to Electronic Files

ASM Handbook, Volume 1, Properties and Selection: Irons, Steels, and High-Performance Alloys was converted to

electronic files in 1997 The conversion was based on the Fourth Printing (1995) No substantive changes were made to the content of the Volume, but some minor corrections and clarifications were made as needed

ASM International staff who contributed to the conversion of the Volume included Sally Fahrenholz-Mann, Bonnie Sanders, Scott Henry, Grace Davidson, Randall Boring, Robert Braddock, and Kathleen Dragolich The electronic version was prepared under the direction of William W Scott, Jr., Technical Director, and Michael J DeHaemer, Managing Director

Copyright Information (for Print Volume)

Copyright © 1990 by ASM International

All Rights Reserved

Metals Handbook is a collective effort involving thousands of technical specialists It brings together in one book a wealth

of information from world-wide sources to help scientists, engineers, and technicians solve current and long-range problems

Great care is taken in the compilation and production of this Volume, but it should be made clear that no warranties, express or implied, are given in connection with the accuracy or completeness of this publication, and no responsibility can be taken for any claims that may arise

Nothing contained in the Metals Handbook shall be construed as a grant of any right of manufacture, sale, use, or

reproduction, in connection with any method, process, apparatus, product, composition, or system, whether or not covered

by letters patent, copyright, or trademark, and nothing contained in the Metals Handbook shall be construed as a defense

against any alleged infringement of letters patent, copyright, or trademark, or as a defense against liability for such infringement

Comments, criticisms, and suggestions are invited, and should be forwarded to ASM International

Library of Congress Cataloging-in-Publication Data (for Print Volume)

Metals Handbook/Prepared under the direction of the ASM International Handbook Committee _10th ed Includes bibliographies and indexes Contents: v 1 Properties and Selection: Irons, Steels, and High-Performance Alloys

1 Metals Handbooks, manuals, etc I ASM International Handbook Committee II Title: ASM Handbook

TA459.M43 1990 620.1'6 90-115

ISBN 0-87170-377-7 (v.1)

SAN 204-7586

ISBN 0-87170-380-7

Printed in the United States of America

Classification and Basic Metallurgy of Cast Iron

Doru M Stefanescu, The University of Alabama

Classification

Historically, the first classification of cast iron was based on its fracture Two types of iron were initially recognized:

plates; it is the result of metastable solidification (Fe3C eutectic)

• Gray iron: Exhibits a gray fracture surface because fracture occurs along the graphite plates (flakes); it

is the result of stable solidification (Gr eutectic)

With the advent of metallography, and as the body of knowledge pertinent to cast iron increased, other classifications based on microstructural features became possible:

(vermicular) graphite (CG), and temper graphite (TG); temper graphite results from a solid-state reaction (malleabilization)

This classification is seldom used by the floor foundryman The most widely used terminology is the commercial one A first division can be made in two categories:

The correspondence between commercial and microstructural classification, as well as the final processing stage in obtaining common cast irons, is given in Table 1 A classification of cast irons by their commercial names and structure is

also given in the article "Classification of Ferrous Casting Alloys" in Casting, Volume 15 of ASM Handbook, formerly 9th Edition Metals Handbook

Table 1 Classification of cast iron by commercial designation, microstructure, and fracture

Commercial designation Carbon-rich phase Matrix (a) Fracture Final structure after

Gray iron Lamellar graphite P Gray Solidification

Ductile iron Spheroidal graphite F, P, A Silver-gray Solidification or heat treatment

Compacted graphite iron Compacted vermicular graphite F, P Gray Solidification

White iron Fe 3 C P, M White Solidification and heat treatment (b)

Mottled iron Lamellar Gr + Fe 3 C P Mottled Solidification

Malleable iron Temper graphite F, P Silver-gray Heat treatment

Austempered ductile iron Spheroidal graphite At Silver-gray Heat treatment

(a) F, ferrite; P, pearlite; A, austenite; M, martensite; At, austempered (bainite)

(b) White irons are not usually heat treated, except for stress relief and to continue austenite

transformation

Special cast irons differ from the common cast irons mainly in the higher content of alloying elements (>3%), which promote microstructures having special properties for elevated-temperature applications, corrosion resistance, and wear resistance A classification of the main types of special cast irons is shown in Fig 2

Fig 2 Classification of special high-alloy cast irons Source: Ref 1

Reference cited in this section

1 R Elliot, Cast Iron Technology, Butterworths, 1988

Principles of the Metallurgy of Cast Iron

The goal of the metallurgist is to design a process that will produce a structure that will yield the expected mechanical properties This requires knowledge of the structure-properties correlation for the particular alloy under consideration as well as of the factors affecting the structure When discussing the metallurgy of cast iron, the main factors of influence on the structure that one needs to address are:

• Chemical composition

• Cooling rate

• Liquid treatment

• Heat treatment

In addition, the following aspects of combined carbon in cast irons should also be considered:

• In the original cooling or through subsequent heat treatment, a matrix can be internally decarburized or carburized by depositing graphite on existing sites or by dissolving carbon from them

• Depending on the silicon content and the cooling rate, the pearlite in iron can vary in carbon content

This is a ternary system, and the carbon content of pearlite can be as low as 0.50% with 2.5% Si

• The conventionally measured hardness of graphitic irons is influenced by the graphite, especially in gray iron Martensite microhardness may be as high as 66 HRC, but measures as low as 54 HRC conventionally in gray iron (58 HRC in ductile)

• The critical temperature of iron is influenced (raised) by silicon content, not carbon content

The following sections in this article discuss some of the basic principles of cast iron metallurgy More detailed descriptions of the metallurgy of cast irons are available in separate articles in this Volume describing certain types of cast

irons The Section "Ferrous Casting Alloys" in Casting, Volume 15 of ASM Handbook, formerly 9th Edition Metals Handbook, also contains more detailed descriptions on the metallurgy of cast irons

Gray Iron (Flake Graphite Iron)

The composition of gray iron must be selected in such a way as to satisfy three basic structural requirements:

• The required graphite shape and distribution

• The carbide-free (chill-free) structure

• The required matrix

For common cast iron, the main elements of the chemical composition are carbon and silicon Figure 3 shows the range of carbon and silicon for common cast irons as compared with steel It is apparent that irons have carbon in excess of the maximum solubility of carbon in austenite, which is shown by the lower dashed line A high carbon content increases the amount of graphite or Fe3C High carbon and silicon contents increase the graphitization potential of the iron as well as its castability

Fig 3 Carbon and silicon composition ranges of common cast irons and steel Source: Ref 2

The combined influence of carbon and silicon on the structure is usually taken into account by the carbon equivalent (CE):

CE = % C + 0.3(% Si)

Additional information on carbon equivalent is available in the article "Thermodynamic Properties of Iron-Base Alloys"

in Casting, Volume 15 of ASM Handbook, formerly 9th Edition Metals Handbook Although increasing the carbon and

silicon contents improves the graphitization potential and therefore decreases the chilling tendency, the strength is adversely affected (Fig 4) This is due to ferrite promotion and the coarsening of pearlite

Fig 4 General influence of carbon equivalent on the tensile strength of gray iron Source: Ref 2

The manganese content varies as a function of the desired matrix Typically, it can be as low as 0.1% for ferritic irons and

as high as 1.2% for pearlitic irons, because manganese is a strong pearlite promoter

From the minor elements, phosphorus and sulfur are the most common and are always present in the composition They can be as high as 0.15% for low-quality iron and are considerably less for high-quality iron, such as ductile iron or compacted graphite iron The effect of sulfur must be balanced by the effect of manganese Without manganese in the iron, undesired iron sulfide (FeS) will form at grain boundaries If the sulfur content is balanced by manganese, manganese sulfide (MnS) will form, which is harmless because it is distributed within the grains The optimum ratio between manganese and sulfur for an FeS-free structure and maximum amount of ferrite is:

a limited number of nuclei Large eutectic cell size and low undercoolings are common in cast irons exhibiting this type

of graphite Type C graphite occurs in hypereutectic irons as a result of solidification with minimum undercooling Type

D graphite is found in hypoeutectic or eutectic irons solidified at rather high cooling rates, while type E graphite is characteristic for strongly hypoeutectic irons Types D and E are both associated with high undercoolings during solidification Not only graphite shape but also graphite size is important, because it is directly related to strength (Fig 7)

Fig 5 Typical flake graphite shapes specified in ASTM A 247 A, uniform distribution, random orientation; B,

rosette groupings; C, kish graphite (superimposed flake sizes, random orientation); D, interdendritic segregation with random orientation; E, interdendritic segregation with preferred orientation

Fig 6 Characteristic cooling curves associated with different flake graphite shapes TE, equilibrium eutectic temperature

Fig 7 Effect of maximum graphite flake length on the tensile strength of gray iron Source: Ref 3

Alloying elements can be added in common cast iron to enhance some mechanical properties They influence both the graphitization potential and the structure and properties of the matrix The main elements are listed below in terms of their graphitization potential:

High positive graphitization potential (decreasing positive potential from top to bottom)