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83-2679- 1933 1

NBSIR 83-2679-1 01)

Technical Aspects of

Critical Materials Use

by the Steel Industry

Volume I: Summary Report

Center for Materials Science

National Bureau of Standards

U.S. Department of Commerce

NBSIR 83-2679-1

Technical Aspects of

Critical Materials Use

by the Steel Industry

Volume I: Summary Report

WATIOI'AL bureau

OF STANDARDS

LIBRARY _ QC

I

Robert Mehrabian

John D. McKinley

Bruce W. Steiner

Kirit J. Bhansali

April 1983

U.S. Department of Commerce, Malcolm Baldrige, Secretary

National Bureau of Standards, Ernest Ambler, Director
'
Preface

This report was prepared by the Center for Materials Science (CMS)

for the Department of Commerce as a technical chapter in the Department's

study of "Critical Materials Requirements of the U.S. Steel Industry."

That study resulted from a Commerce Department responsibility under the

"National Materials and Minerals Policy, Research and Development Act

of 1980," (PL 96-479) to "continually identify and assess —(materials

needs) cases as necessary to ensure an adequate and stable supply of

materials to meet national security, economic well being, and industrial

production needs."

This report reviews technical opportunities for research in process

improvement and in alternative materials development that would reduce

U.S. dependency on critical materials.

The advanced technologies reviewed here, in addition to their implications for critical materials conservation, represent trends leading to

better quality and lower cost steel products. Thus, they may also contribute positively to the industry's more immediate concern for improved

markets.

The report draws extensively on material presented at a public

workshop sponsored jointly by the National Bureau of Standards, Bureau

of Mines, and the Army Research Office. The workshop, "Critical Material

Requirements for Steels of the Future; Conservation and Substitution for

Chromium," was held at Vanderbilt University, October 4-7, 1982; it

featured 50 presentations by technical authorities from steel producing

and using industries. The Proceedings of that Workshop are published

as Volume II of this Report.
Contents

VOLUME I: SUMMARY REPORT

EXECUTIVE SUMMARY ix

INTRODUCTION 1

PROCESSING 6

Current Economic Status of the Industry 6

Technical Status of the Three Major Sectors ... 7

Technical Developments in Processing 9

Continuous Casting 9

Primary Melting and Refining Processes ... 10

Real-Time Control 13

Near Net Shape Technology 15

Surface Modification 16

Steel Plant Refractories 18

Import Implications of Advanced Technical

Developments 19

Recycling 20

SUBSTITUTION 23

Chromium Functions in Steel 24

Substitution Options for Chromium in Corrosion

and Oxidation Resistant Stainless Steels ... 24

Substitution Options for Chromium in Structural

Alloy Steels 29

INSTITUTIONAL FACTORS 32

Specifications 32

Qualification 32

Composition of the Natural Defense Stockpile . . 33

Research 34

CRITICAL MATERIALS AND PRODUCTIVITY 37

REFERENCES 39
VOLUME II A: Proceedings of a Public Workshop; "Trends in Critical Materials

Requirements for Steels of the Future; Conservation and

Substitution Technology for Chromium".

Significance of the Workshop

CRITICAL MATERIALS NEEDS FOR FUTURE STEELS AND THE CHALLENGE OF THE

CHROMIUM SITUATION, Allen G. Gray, Workshop Organizer and Chairman;

Vanderbilt University and American Society for Metals. PI

Workshop Keynote Session

INDUSTRIAL LIFE WITHOUT CHROMIUM-TECHNOLOGICAL CHALLENGES, Arden L. Bement, Jr., TRW Inc. P2

POTENTIAL FOR CRITICAL MATERIALS CONSERVATION IN THE INTEGRATED STEEL

INDUSTRY, Gordon H. Geiger, Chase Manhattan Bank. P3

POTENTIAL AREAS FOR CHROMIUM CONSERVATION IN STAINLESS STEELS,

R. A. Lula, Consultant. P4

THE VALUE OF GENERIC TECHNOLOGY: SUBSTITUTION BASED ON

HARDENABILITY, Dale H. Breen, Gear Research Institute. P5

Users' Views on Steels Needed For The Future Technological

Trends on Critical Materials Required For These Steels

TRENDS AND NEEDS FOR FUTURE STEELS IN BUILDINGS AND BRIDGES,

Lewis Brunner, American Institute of Steel Construction. P6

THE MATERIALS USE AND RESEARCH OUTLOOK IN THE RAILWAY INDUSTRY,

William J. Harris, Association of American Railroads. P7

TRENDS AND NEEDS FOR FUTURE AUTOMOTIVE STEELS, George H. Robinson,

General Motors Corporation. P8

CATERPILLAR TRACTOR CO. VIEWS ON STEELS NEEDED FOR FUTURE

APPLICATIONS, Dennis B. O'Neil, Caterpillar Tractor Co. P9

CHEMICAL EQUIPMENT - USER'S VIEWS ON STEELS NEEDED FOR THE FUTURE,

Edward A. Kachik, Materials Technology Institute. P10

ELECTRIC UTILITY VIEW OF THE USE OF CRITICAL METALS IN STEEL,

Robert I. Jaffee, Electric Power Research Institute. Pll

THE USE OF CHROMIUM IN STEELS FOR AEROSPACE, Rod Simenz,

Lockheed-Cal ifornia Co. P12

USER'S VIEWS - OIL COUNTRY USAGE TRENDS IN CRITICAL MATERIALS FOR

STEELS OF THE FUTURE - CHROMIUM, John W. Kochera, Shell Development

Co. P13

v
Impact of Developments in Manufacturing and Process

Controls on Conservation and Recovery of Critical Materials

STAINLESS AND SPECIALTY STEELS AOD, EBR, LR, VAR, VIM, VOD, James

T. Cordy, Universal Cyclops Specialty Steels Co. P14

MINI MILLS-TECHNOLOGICAL INNOVATIONS AND FUTURE ALTERNATIVES,

Peter H. Wright, Chaparral Steel Co. P15

FUTURE RAW-MATERIAL REQUIREMENTS FOR STEEL PLANT REFRACTORIES,

David H. Hubble and K. K. Kappmeyer, U.S. Steel Corp. P16

RECYCLING-PRESENT AND FUTURE: "POTENTIAL FOR CONSERVATION"

Herschel Cutler, Institute of Scrap Iron and Steel. P17

Conservation and Substitution For Chromium in Stainless

Steels for Chemical Use and For Corrosion Resistant Applications

AN OVERVIEW OF THE POTENTIAL FOR CHROMIUM CONSERVATION IN STAINLESS

STEELS FOR CORROSION APPLICATIONS, Gerald L. Houze Jr., Allegheny

Ludlum Steel Corporation. P18

SUMMARY OF STUDIES OF METAL PROPERTIES COUNCIL ON CHROMIUM

CONSERVATION IN STAINLESS STEELS FOR CORROSION APPLICATIONS,

A. 0. Schaefer, Metal Properties Council. P19

CHROMIUM CONSERVATIONS IN STAINLESS STEELS: STATUS OF MPC ACTIVITY,

Jim Heger, Consultant, Metal Properties Council. P20

CHROMIUM SUBSTITUTION PLANNING AT THE AMERICAN STERILIZER COMPANY,

Roy S. Klein, The American Sterilizer Co. P21

ALTERNATES FOR STAINLESS STEELS IN THE CHEMICAL PROCESS INDUSTRIES,

Edward A. Kachik, Materials Technology Institute of Chemical

Processing Industries. P22

OPPORTUNITIES FOR CONSERVATION OF CHROMIUM IN CHEMICAL PROCESS

EQUIPMENT, Robert A. Gaugh, ARMCO Inc. P23

APPROACHES TO CHROMIUM CONSERVATION IN MATERIALS FOR CHEMICAL

PROCESSING INDUSTRIES, Aziz I. Ashpahani , Cabot Corporation. P24

POTENTIODYNAMIC CORROSION BEHAVIOR FOR SEVERAL FE-MN-AL AUSTENITIC

STEELS, Rosie Wang and R. A. Rapp, Ohio State University. P25

VI
VOLUME II B: Proceedings of a Public Workshop; "Trends in Critical Materials

Requirements for Steels of the Future; Conservation and

Substitution Technology for Chromium".

Conservation and Substitution For Chromium in

Stainless Steels and Alloys For Heat Resistant Application

OUTLOOK FOR CONSERVATION OF CHROMIUM IN SUPERALLOYS, John K. Tien,

Juan M. Sanchez, and Robert N. Jarrett, Center for Strategic

Materials, Columbia University. P26

DEVELOPMENT OF 9 CR-1 MO STEEL, Vinod K. Sikka, Oak Ridge National

Laboratory. P27

SILICON-MOLYBDENIUM DUCTILE IRON FOR ELEVATED TEMPERATURE SERVICE

TO CONSERVE CHROMIUM, Jan Janowak, Climax Molybdenum Co. P28

THE 1982 STATUS REPORT OF MN-AL-FE STEELS AS REPLACEMENT FOR

STAINLESS IN HEAT RESISTING AND CRYOGENIC APPLICATIONS,

Samir K. Banerji, Foote Minerals Co. P29

Conservation and Substitution For Chromium

in Carburizing, Heat Treatable Steels and Bearing Steels

THE DEVELOPMENT OF NEW ALLOYS TO REPLACE CHROMIUM IN CARBURIZING

STEELS FOR GEARS AND SHAFTS-, Carl J. Keith and V. K. Sharma,

International Harvester Co. P30

CHROMIUM-FREE STEELS FOR CARBURIZING, George T. Eldis, D. E.

Diesburg, and H. N. Lander Climax Molybdenum Co. P31

RARE EARTH BORON STEEL (25-Mn-Ti-B) GEARS REPORT FROM NANCHANG

GEAR PLANT, BEIJING, CHINA, Presented by Dale H. Breen and Allen G.

Gray. P32

POTENTIAL FOR SELECTIVE HARDENING BY INDUCTION IN CHROMIUM-FREE

STEELS, Peter A. Hassell, Ajax Magnethermic Corp. P33

BEARING STEELS OF THE 52100 TYPE WITH REDUCED CHROMIUM, Chester F. Jatczak, The Timken Co. P34

Conservation and Substitution For Chromium in Structural

Alloy, High Strength, and High Strength Low Alloy Steels

AN OVERVIEW OF CONSERVATION AND SUBSTITUTION FOR CHROMIUM IN

STRUCTURAL ALLOY, HSLA AND ULTRA HIGH STRENGTH STEELS, Robert T.

Ault, Republic Steel Corporation. P35

ALTERNATIVE COMPOSITIONS FOR FUTURE HSLA STEELS, Brian L. Jones,

Niobium Products Co. P36

vii
Potential For Advanced Technologies in Chromium

Conservation-Coating Systems And Surface Modification

Technology; Ceramics, Composites And Intermetal 1 ics

OPPORTUNITIES FOR SURFACE MODIFICATION TECHNOLOGY IN CONSERVATION OF

CHROMIUM, Peter G. Moore, Naval Research Laboratory. P37

SALT BATH TREATING AS AN ALTERNATIVE FOR CHROMIUM PLATING,

William G. Wood, Kolene Co. P38

CLAD METALS: MATERIAL CONSERVATION THROUGH DESIGN FOR CORROSION

CONTROL AND HIGH PERFORMANCE, James T. Skelly, Texas Instruments,

Inc. P39

POTENTIAL FOR POLYMER CONCRETE TO CONSERVE ALLOYS IN ENGINEERING

APPLICATIONS, Jack J. Fontana, Brookhaven National Laboratory. P40

ELECTROLESS NICKEL AS A SUBSTITUTE FOR CHROMIUM PLATING IN

INDUSTRIAL APPLICATIONS, Ronald N. Duncan, Elnic Inc. P41

DEVELOPMENT OF DUCTILE POLYCRYSTALLINE NKAL FOR HIGH TEMPERATURE

APPLICATIONS, C.T. Liu and C.C. Koch, OakJ Ridge National Laboratory. P42

INJECTION MOLDING CERAMIC PARTS FOR HIGH TEMPERATURE APPLICATIONS,

Beebhas C. Mutsuddy and Dinesh K. Shetty, Battel le-Columbus

Laboratories. P43

Information Stockpile - Summary of Comments

DEVELOPING AN INFORMATION STOCKPILE TO AID IN SUBSTITUTION

PREPAREDNESS, Robert T. Nash, Vanderbilt University. P44
EXECUTIVE SUMMARY

The present review of critical materials requirements in the

American steel industry is particularly timely because of the severe

depression being felt in the sale of steel, caused by the current

world-wide recession, and compounded by increasingly strong competition

from abroad. This competition is viewed as an unusually severe challenge

because it is based on capital-intensive advanced processing technologies,

which American companies now find difficult to finance. For the U.S.

industry, the key to a strong competitive position is better performance,

superior product quality, and reduced costs. These in turn will be

achieved through technical developments in processing and in innovative

materials. The nature and direction of the advances in these two technical areas will influence strongly the industry's future materials

requirements.

Processing trends will affect demand for all raw materials, but

differ in detail among the three major sectors of the industry: specialty

producers, mini mills, and integrated mills. The specialty steel

sector has stayed relatively competitive through technolgical leadership.

The mini mill sector has remained relatively healthy through use of

advanced technology, much of it developed abroad, and by careful limitation of product lines and proximity to materials and customers. Integrated

mills have increased their use of advanced continuous casting technology

to 22%, but foreign competition is much farther along the road to

optimal implementation of continuous production.

In addition to completion of the move to continuous casting, a

move to fully automated, real-time controlled ladle metallurgy will

increase productivity and quality control in the integrated sector.

Moreover, the increasing emphasis on the production of "clean steels"

IX
has the potential to decrease our need for imported materials while at the

same time increasing the performance of our steels and therefore our competitiveness in world markets. These "clean steels" depend on sophisticated

processing to achieve desired properties rather than on large quantities

of alloying elements. The broader application of near net shape and

surface modification technologies is expected to have similar effects.

Some advanced processing technologies such as the argon oxygen

decarburization process increase the relative attractiveness of South

African ferrochrome over more expensive types from other parts of the

world. The resulting increased dependence on South African ferrochrome

will be modified, however, by lower overall demand due to a decreasing

requirement for chromite refractories and a decreased need for chromium

in a broad spectrum of advanced materials.

Use of recycled materials is one factor in the success of the mini

mills. There is substantial room for increased use of recycled materials

in integrated production.

Raw materials for which the American steel industry does not have

North American supplies commercially available are chromium, manganese,

columbium, and cobalt. These are therefore the materials for which

alternatives are particularly important.

In the steel industry, cobalt is used primarily for tool steels,

for which non-cobalt-containing alloys are commercially available.

Substitutes for columbium and manganese have also been identified,

although they are not so economical as the alloys containing columbium

and manganese. Moreover, the quantities of manganese required are such

that substitution of a substantial fraction would disrupt the markets

for the alternatives. Because chromium is so inexpensive and provides a

x
variety of special functions in steels, cost effective alternatives to

chromium have not been proven for many of its uses. A number of opportunities exist, however.

Chromium is used primarily in two types of steels. The largest

single use of chromium is in stainless steels, to which chromium imparts

corrosion resistance, oxidation resistance, and stabilization of the

austenitic structure. Chromium is used also in structural steels, to

which chromium imparts strength, especially in high temperature applications, fatigue resistance, especially in ultrahigh strength steels, and

hardenabi 1 ity.

Although no other element is known to produce corrosion resistance

comparable to that imparted by chromium, the chromium content of the

most widely used stainless steels, austenitic stainless steels, can be

reduced without impairing corrosion resistance in many applications for

which the traditional 18 percent is unnecessary. Use of duplex steels

with large amounts of chromium may actually reduce chromium use by

permitting substantially smaller amounts of these high strength steels

to replace the traditional types. Near net shape and coating technologies

can also reduce the amounts of chromium required.

For many specific appi cations of these materials, other materials

without chromium are commercialy available or apppear feasible. For

air oxidation at high temperature chromium may be replaceable by aluminum,

although processing is extremely difficult. In structural applications,

chromium-free grades are commercially available, and computerized

models for new alloy design are currently available. Non steel alternatives such as titanium, tantalum, glass, and plastics also provide

potential alternatives in some applications.

xi
Although a number of technical alternatives are either commercially

available or are believed to offer real promise, several institutional

barriers impede their exploitation. In some cases the current levels

of imported constituents are no longer required because of changes in

processing technology but continue to be used because specifications

have not have not yet been modified. In other cases, elaborate qualification procedures discourage experimentation with alternatives. The

utility of the chrome ore in the National Defense Stockpile is dropping

rapidly as our ability to process this raw material is lost to less

expensive foreign suppliers in South Africa. Finally, the realization

of the promise of a number of the alternative technologies will require

research and development to verify performance and to establish costeffective production.

XI 1
INTRODUCTION

In the present economic climate featuring weak markets, active

foreign competition, and expensive capital, financial survival is the

immediate concern of much of the U.S. steel industry; technical issues

including critical materials needs seem less urgent. At the same time,

competitive strength is closely correlated with the use of modern

technology, to achieve better performance, superior product quality,

and reduced cost. These are being achieved through technical developments

in processing and new materials. The nature and direction of advances

in these two technical areas will influence strongly the industry's

future raw material requirements. This Summary Report identifies the opportunities in advanced processing and alternative materials that are likely

to be the most important factors in the future of U.S. steel industry

and for the raw materials required in the production of steel.

A wide range of materials is used in steel making because steels

with a wide variety of properties and many engineering uses are demanded.

Substantial quantities of manganese, chromium, molybdenum, nickel,

tungsten, columbium, boron, silicon, vanadium, aluminum, and titanium

are used in current steel technology for alloying. Tin and zinc are

used as well for coating. These materials are "critical" in the sense

that they are essential to the production of certain types of steel (using

existing processes) and in the sense that changes in the availability of

some would affect profoundly the cost structure and product mix of the

steel industry and of the industries that use steel. The sudden necessity

to use unfamiliar materials would inject uncertainty and jeopardize performance in affected industries and defense planning.

However, not all of these materials are "strategic" in the sense

that supplies are highly uncertain. Molybdenum, boron, silicon, and

1
vanadium are produced commercially in the United States although

40 percent of the vanadium used is imported. For aluminum there are

commercial domestic bauxite sources as well as major commercial sources

in Jamaica. Domestic titanium ores are utilized for titanium dioxide

production.

The American Iron and Steel Institute (AISI) identifies the

following alloying materials used for steel production as those on

which the U.S. is most seriously import dependent: chromium, manganese,

cobalt, nickel, and tungsten^:

Chromi urn is used in structural and specialty steels where it

imparts hardenabi 1 ity , corrosion resistance, oxidation resistance, and

high temperature strength.

Manganese is used in the processing of all steels for deoxidation,

desulfurization, or control of carbide and sulfide morphology. In the

finished steel it provides toughness, strength hardenabi 1 ity , and

hardness.

Cobalt is used primarily in tool steels and in some high strength

steels; it contributes to high temperature strength and increases

carbide tool life by acting as a binder.

Nickel increases hardenabi 1 ity and improves strength and toughness

in specialty steels; nickel establishes the austenitic structure in

high chrome steels; it is added with chromium to increase corrosion or

oxidation resistance and high temperature strength.

Tungsten is used in tool steels to stabilize carbides; it develops

high temperature hardness, contributes to creep strength, and increases

hardenabi 1 ity.

In addition to the five elements listed above, columbium is 100 percent imported, primarily as ferrocol umbium for steel production. It is

2
used in high strength low alloy steels as a strengthening agent, in

austenitic stainless steels as a carbide stabilizer and in carbon

steels.

For these elements the probability for total supply disruption

varies significantly. Nickel and tungsten are now obtained from large

domestic and Canadian sources. Two thirds of U.S. columbium demand is

currently supplied by Brazil, which has sources of high grade low cost

ore capable of supplying 70 percent or more of world demand through the

year 2000. There are also domestic sources now inactive that could be

reopened in the event of a price rise. About 90 percent of U.S. cobalt

demand is now supplied by imports mainly from Zaire and Zambia. For

cobalt two formerly commercial domestic sources are available that

could be developed in an emergency. Manganese is almost totally imported;

manganese sources are distributed world-wide including potentially

significant reserves in Mexico and large commercially developed high

grade sources in Africa, Australia, Brazil, and India. Finally, chromium

is not available in the western hemisphere, and a centralization of

2 supply in southern Africa is projected after the turn of the century .

In summary, current sources for columbium, cobalt, chromium, and manganese

are all foreign, and for the first three of these, the sources are highly

local ized.

The American Iron and Steel Institute classifies steels into four

groups according to maj'or alloying element content as follows:

o Carbon Steels : Properties for these steels are determined

primarily by carbon content; these steels always contain

manganese (up to 1.65 percent) and usually minor amounts of

sulfur, silicon, and phosphorus. These are high volume

3
steels with diverse uses in plate, castings, tubing, wire

products, structural shapes, strip, and rails,

o Alloy Steels : Alloy steels are those that contain more than

1.65 percent manganese, 0.6 percent silicon, 0.6 percent

copper or other specified elements. An important subgroup,

high strength low alloy (HSLA) steels, contain minor but

important amounts of one or more of the following elements:

manganese, silicon, copper, vanadium, zirconium, nickel,

columbium, titanium, and chromium. Alloy steels are used

primarily for structural applications,

o Stainless and Heat Resisting Steels : These steels contain

chromium and often nickel in concentrations as high as 30 percent;

high volume grades contain 18 percent chromium, and 8 percent

nickel. Stainless steels are used for special or structural

applications requiring corrosion resistance, oxidation resistance, and/or high temperature strength. Large amounts are

also used for decorative and functional applications such as

automobile wheel covers and trim, kitchen sinks and flatware,

o Tool Steels : These steels contain substantial amounts of

cobalt, tungsten, molybdenum, and some chromium. They are

used for operations requiring hardness and wear resistance.

As noted above, the development of technology in two particular

areas, processing and innovative materials, can greatly affect future

raw materials requirements for steel production. Technological changes

in processing that will affect materials requirements are discussed in

the next section. Potential alternative materials are reviewed following

4
that. Resulting institutional questions are summarized next. Finally,

the relationship between materials requirements and industrial productivity is reviewed.

Cobalt substitution and conservation was addressed in a 1981

Workshop at NBS on aerospace industry materials. In order to obtain

recent information on important developments and trends in chromium

conservation since the mid 1970s, when its use was reviewed comprehen3 sively , the National Bureau of Standards in concert with the Bureau of

Mines and the Army Research Office, organized a public workshop at

Vanderbilt University in October 1982. This workshop, "Trends in

Critical Materials Requirements for Steels of the Future; Conservation

and Substitution Technology for Chromium," provided important verification of many technical trends already evident at the time of the National

Materials Advisory Board study.

5
PROCESSING

Current Economic Status of the Industry

Rapid changes that are now taking place in steel technology improve

both performance and yields. This innovation will therefore affect

profoundly the requirements for all raw materials. However, an analysis

of the technological opportunities presented to the steel industry must

recognize that the current financial climate of the industry is extremely

4-7

serious . The survival of large segments of the U.S. steel industry

is felt to be at stake. The implementation of known technological

opportunities and the definition of new technical approaches that will

improve future productivity are recognized as essential to the future

of the industry, but are now seen as hostage to the introduction of new

capital in the integrated steel industry.

Current slackness in demand for steel is a worldwide phenomenon.

It derives in part from the general recession, but is more ominous than

the status of other sectors because of overcapacity for steel production

in the world as a whole. The resulting concern in the U.S. steel

industry for its markets is compounded by the increasing pace of technoO

logical developments in recent years and the current inability of the

U.S. steel industry to finance the capital investment required to

exploit these developments threatens to further weaken the U.S. international competitive position.

A review of materials requirements of the industry and associated

technical opportunities must take into account the overwhelming importance

to the industry of this question of survival. The current competitive

6
position of the industry and the world economic climate severely limit

the nature and timing of action that can be beneficial. However, this

review of the technological trends of the industry as it faces the

necessity for major investments in capital equipment is particularly

timely precisely because of the choices in technology that are now

available, and that must be faced and anticipated as the industry girds

itself for the future.

Technical Status of the Three Major Sectors

The steel industry can be divided into three major sectors for the

purposes of this analysis: the large integrated mills, the mini mills,

and the specialty steel sector.

The integrated mills produce the bulk of the steels made in the

U.S. Carbon and low alloy steels, which constitute the largest volume

of steel production, are made primarily in plants that individually

produce in excess of two million tons annually. This heavily capitalized

sector of the industry faces the greatest challenge in modernization in

order to improve its international competitive position. This challenge

is exacerbated by a general shift in the market toward alloy steels.

As already noted, a primary concern with respect to the integrated

mill sector is its current inability to finance the development and

acquisition of efficient production technology for traditional steels

5 and for advanced low alloy steels . In planning for the modernization

of production technology through capital investment, the industry needs

to anticipate changes in demand for alloy steels. Of particular importance in anticipating future markets is recently increased understanding

7
and control of processing technology, which enables producers to achieve

properties through specialized processing rather than through the

addition of relatively large quantities of alloying elements. For

example, the growth in demand for HSLA steels is likely to continue as

9 demand for these steels spreads into areas such as automobiles .

The mini mill sector concentrates on a small range of products

from among carbon and low alloy steels which are made in mills individually producing less than one million tons annually. By thus restricting

the product range and the relatively low level of capitalization required,

and through low transportation costs made possible by utilization of

locally generated scrap and marketing in the vicinity of the plant, the

mini mill sector has remained profitable even through the current

recession^. Although mini mills have achieved success by concentrating

on relatively high volume, low cost steels, the success of these mills

is traceable in part also to the introduction of innovative processing

technology. In this case however, in contrast to the specialty steel

industry, the technology has not been developed by the producers themselves. Much that is used in fact comes from abroad. The importance

of potential foreign competition for markets in this sector is mitigated

by the dominance of transportation costs in the relatively low cost

product. The manufacturing technology of the mini mills is continuing

to develop rapidly"^.

The specialty steel industry, which produces not only stainless

steels and tool steels but also superalloys, has remained relatively

profitable through leadership in innovation that makes it technically

competitive worldwide. This sector is of particular importance in a

review of imported materials requirements of the industry because the

8
production of stainless steel alone consumes more than half of all of

the chromium used in the U.S. economy.

The technical leadership of the specialty steel industry has been

achieved and maintained through the development and introduction into

practice of a series of processing technology breakthroughs, which in

turn have stimulated the development of a wide range of steels serving

other high technology industries^.

Thus, change in technology is central to the competitive status of

all three steel industry sectors. The changes differ in the three

sectors, but in no case are they due to uncertainty over raw materials

supplies. However, investment choices to ensure that the steel industry

be competitive world-wide must be made during a period when supply

uncertainties need to be anticipated.

Technical Developments in Processing

As already noted, innovation in processing will affect strongly

both the performance of steel and the yields in its production. This

innovation will therefore affect future raw material requirements in

the industry, especially the requirements for non-ferrous additives.

Continuous Casting

Continuous casting has been introduced in all major sectors of the

steel industry. It offers improved quality over previous processing

technology: better homogeneity, beneficial inclusion morphology and

distribution, and better surface quality. At the same time it offers

substantial cost advantages through reduced cropping, energy consumption^,

9
and for some production the elimination of the blooming mill. Yield

11-13 improvement varies with steel grade from 10 to 20 percent .

Domestic production by continuous casting has increased as a

proportion of total production, from 9 percent in 1975 to 22 percent in

1981^. Most of the bar and rod production is continuous cast today

5 13 along with a substantial fraction of the "flat" production ’

. Large

structural pieces are not continuously cast. The use of continuous

14 casting is growing and is expected to penetrate 45 percent of the

industry by 1990. However, in 1981 Japan and Europe already produced

71 and 45 percent of their steels, respectively, by continuous casting.

The severe challenge presented by foreign steel is ascribed in part to

their advances in this area. The success of the mini mill sector of

the U.S. production is due in part to the fact that it uses continuous

casting exclusively, thereby achieving an increase in yield over ingot

practice of 18 percent'^.

The use of continuous casting technology by the specialty steel

sector is considered to be fully competitive with the practices of

foreign producers^. Use of this technology has been credited with an

improvement for chromium yield in stainless steel of 10 to 15 percent

when used in conjunction with the argon-oxygen decarburization (AOD)

process'^ Both the improved performance of the resulting product

and the improvements in yield lower requirements for raw materials.

Primary Melting and Refining Processes

Specific properties in steels have traditionally been established

by the incorporation of alloying elements. Common alloys contain such

elements at a level of 2% to 4%. The most widely used stainless steels

10
contain about 18% chromium. In order to achieve unusual properties,

the metallurgist may add even larger quantities of chromium. For

example, special alloys such as some special welding electrodes contain

30% chromium and 9% nickel.

Recent developments in duplex processing, separate electric furnace

melting and ladle refining in particular AOD, have significantly improved

the manufacture of stainless steel. It is difficult to decarburize by

oxidation without also oxidizing the chromium. The traditional way to

handle this challenge is to decarburize low chromium melts and then

bring the chromium composition up to its final value by the addition of

expensive low-carbon ferrochrome. In addition, decarburization must be

performed at high temperatures in order to minimize but not eliminate

substantial losses of chromium due to oxidation. Modern refining

options such as AOD lower the carbon monoxide partial pressure by

blowing varying proportions of argon-oxygen mixtures. The throughput

of argon removes the carbon monoxide reaction product and permits

continued oxidation of the carbon at lower tempratures in the presence

of the final amount of chromium. The economic benefits from duplexing

processes include use of lower cost raw materials (e.g., high carbon

ferrochromium) , improved chromium recovery, and lower processing costs

through lower processing temperatures.

Utilization of vacuum refining exploits the pressure dependence of

the carbon oxidation reaction and thus also permits lower decarburization

temperatures. The result is simultaneous lower carbon content, and

reduction of chromium loss. Conventional electric furnace melting and

oxygen blowing results in chromium losses of between 10 and 15 percent.

Vacuum-oxygen decarburization (VOD) reduces the chromium loss to 6 percent.

11
Furthermore, the use of either VOD or AOD improves the final properties

of the steels due to their lower gas and impurity contents.

The trend in the production of low alloy construction steels

containing chromium is also toward duplex vacuum refining systems.

Chromium losses of 7 to 10 percent encountered in conventional processing

can be reduced to less than 4 percent.

Recently developed duplex processes, are much more cost effective

than previous processes. New duplex processes allow large-scale removal

of impurities and the subsequent, precise addition of other costly

elements rather than the addition of large quantities of costly alloying

elements to "tie up" high levels of impurities. Process advances have

also helped the development of new alloys such as HSLA steels for the

transportation industry. The need to lighten vehicles in order to save

energy has led to a strong demand for weight reduction and a corrolary

strong demand for these higher quality and higher strength- to-weight

steels. Concern for the high consumption of energy in processing has

added a strong desire to eliminate the energy-expensive elaborate heat

14 12

treatment in fabrication. HSLA steels and other clean steels

successfully provide the needed increased strength without such heat

treatment.

Thus sophisticated processing is being used to produce cost competitive steels that do not require large amounts of alloying elements and

elaborate heat treatment. The success of this approach is based on

achieving an understanding of the specific influence of the various

fabrication process variables on steel microstructures and a detailed

prediction of the properties of steels based upon the microstructures

thus produced. This approach has resulted in the design of new steels

12
with properties superior to those traditionally achieved through the

use of large alloy additions'^.

In duplex steelmaking the achievement of microstructure in high

temperature alloys requires the introduction of special melting and

remelting techniques. Among these are vacuum induction melting (VIM)

and secondary remelting operations such as vacuum arc remelting (VAR)

and electroslag remelting (ESR). The vacuum techniques remove trace

elements that have a high vapor pressure while the refining processes

in, for example, ESR reduce sulfur to very low levels. Fine grain

structure and segregate spacing, which are necessary to the achievement

of the desired high strength and workability, are also achieved in

these processes by use of high cooling rates during solidification.

While these processes reduce impurities to very low levels, they permit

maximum alloy conservation and narrow ranges of composition variations,

hence optimum properties.

The result of this succession of sophisticated melting and refining

steps is the production of steels with reduced losses of critical

alloying elements, and steels with competitive or superior properties.

These properties are achieved, moreover, with a sufficiently low alloy

9 11

content to be cost competitive with traditional steels ’

Real-Time Control

Part of the challenge faced by the U.S. steel industry is the

desire by its customers for improved quality control. Materials problems

18

in the construction of major bridges are an example of this challenge .

A recent study by the National Bureau of Standards and Battel le Columbus

on the national costs of fracture19 identifies the economic... benefits in

13
reducing the range of property variability in structural materials

through processing improvements and tighter quality control. This

would result in more efficient use of construction materials and

therefore a saving in raw materials, including strategic supplies.

This study also notes the importance of non-destructive evaluation and

real-time control during processing for achieving the needed improvement

in variability.

Continuous casting and ladle metallurgy offer the chance to achieve

the improved quality desired^. However, in order to realize this

improvement in fact, closer control of processing will also be necessary,

9 especially for casting, rolling, and annealing . With real-time control,

the more uniform chemical composition, hardenabil ity , toughness, and

surface quality that must be achieved for steels in general, and for

high strength steels in particular, can be produced. Although the

acceptable "window" in properties is constantly being made smaller,

productivity can actually be improved simultaneously through this

control^. Increased productivity will follow not only from the

improved and more consistent properties but also from higher yields

through improved dimensional control and minimization of the remaking

15

of heats , and from more efficient utilization of the energy required

8 14

in heating furnaces ’. Requirements for all raw materials including

chromium will be reduced correspondingly.

The use of dynamic control has already been widely adopted in the

basic-oxygen steel making technology. Here it has lowered oxidation

losses. The computer control of alloy additions is also receiving

increased emphasis^.

The American Iron and Steel Institute and its member companies

have recognized the importance of real-time control in achieving increased

14
productivity. They have noted that the development of sensors was

essential to achieving such active control. Four groups of sensors

were identified to be of primary importance: (1) automatic detection

of porosity; (2) on-line inspection of defects; (3) rapid in-process

chemical analysis of the molten metal, and (4) rapid measurement of the

temperature distribution within a solid or solidifying body of hot

steel. These sensor needs were described to interested scientists and

engineers in a Workshop held at the National Bureau of Standards in

20 July, 1982 . Programs to address these needs are now being developed

by the American Iron and Steel Institute.

Near Net Shape Technology

The production of parts by powder metallurgy minimizes material

and energy utilization^. Moreover, by use of powder formed by rapid

solidification, alloys with special microstructures and therefore with

properties not possible by means of conventional metallurgical techniques

can be made through powder metallurgy.

These microstructures and their concomitant lower segregation can

result in improvements in fracture toughness, corrosion, wear and

oxidation resistance. These properties are of particular interest for

14 alloy steels, tool steels, and stainless steels , high alloy bearings,

2 tools and dies, and jet engine discs . The resulting alloys have

15 improved hot workability and have led to new concepts in alloy design .

Powder metallurgy has received considerable attention both in industrial

research for application in special areas and in government programs

supporting long range basic investigations.

15
The results of these efforts to date have been alloys that have

2 15 already reduced the need for chromium somewhat ’

; further possibilities are foreseen both for the reduction of the fraction of chromium

contained and for the reduction of scrap in fabrication. Other powder

metallurgy techniques are also affecting the balance among various

fabrication technologies. For example, some sintered iron powder parts

9

may replace forged steel in automobiles .

Surface Modification

Three of the principal uses for chromium in steels are resistance

to corrosion, oxidation, and wear. Because these characteristics depend

on surface related properties, surface modification may serve well as a

chromium conservation measure in areas where these properties are

important. Moreover, surface modification can offer distinct advantages.

One is the growing ability to treat surfaces of objects in order to

give them special microstructures not achievable in the bulk at all or

perhaps only by the sacrifice of other desirable properties. Surface

modification thus is not to be viewed just as a substitute but rather

as a processing option. Among the performance advantages are the

2 . . extension of the life of tools and other parts . Particularly promising

options include: cladding and lining, weld overlaying and hardfacing,

21-22

thermal spray coating, surface impregnation such as ion implantation,

23 directed high energy (laser and electron) beam processing , and chemical

and physical vapor deposition.

From the perspective of the steel industry as a whole, surface

modification plays two distinct roles. First, it may be part of the

processing in the steel mill and therefore is to be examined in the

16
context of changing processing technology in the steel industry.

Second, surfaces may also be treated "down stream" by industries that

purchase steel from the steel industry and utilize it in products. The

steel industry has an interest in such technology to the extent that it

modifies anticipated demand for steel of certain types or to the extent

that such later processing will affect requirements for the steel

produced, such as type of surface finish.

13 Improved surface quality can result from bottom forming of ingots

Coatings on the steel produced by the steel industry are also expected

to play a more visible role in product demand. For example, the use of

precoated and galvanized steel will affect demand for bare hot and cold

14 rolled steel . Other special products within the steel industry that

are attracting attention are zinc-aluminum coated sheet steel and

14 nickel-zmc electroplated steel strip . Since high strength steels

are as susceptible to corrosion as are other steels, but are more

vulnerable because of their reduced gage, coatings for these steels are

particularly important. For steels in general, not only is the performance of the material in the final product a factor, but improved

corrosion protection at down stream manufacturing facilities has been

5 identified as an area of concern .

"Down stream" surface modification is growing in importance as the

range of alternatives and the special properties that can be achieved

24

advance rapidly. Among these areas are the electroless nickel process

15 25 11 26 cladding ’

, chromizing, and nitriding ’

. Cladding could affect

chromium utilization either in the form of stainless cladding on base

steels, which could reduce but not eliminate the demand for stainless

steels and the chromium that they contain, or through tantalum,

17
. 27 . zirconium , or titanium cladding, which would eliminate the use of

chromium altogether.

Steel Plant Refractories

Significant shifts have been noted in refractory usage in the

steel industry. These trends are expected to continue in the future

and are due to changes in steel processing, improved steel quality

requirements and the use of more severe environments in the production

of steel. The total refractory usage in steel has declined from 65 to

70 percent of the total refractory consumption in the U.S. in the

28

1960s and 1970s to approximately 50 to 55 percent today . In general,

lower refractory consumption is attributed to improved service life and

the use of sophisticated processing of raw materials. A brief look at

refractory usage in modern ironmaking, steelmaking, refining, and casting

reflects the changing demand for refractories both domestic and imported.

The larger modern blast furnaces with higher operating temperatures

and better process control require more dependable, longer life, refractories containing high-alumina (for which we are import dependent),

silicon carbide, and graphite materials. Reduction in use of refractories

in the face of the more severe environments present in the modern blast

furnaces is traceable to a number of factors. Use of furnace cooling

has grown. Tighter combustion and slag composition controls, gas

cleaning, and the avoidance of other contamination have played a role

as wel 1

.

Open hearth furnaces formerly required a continuing supply of

chromite refractories for use in an environment that made for a

severely limited lifetime. Recent emphasis on basic-oxygen steelmaking

18
has reduced both the overall refractory consumption and changed the mix

of the refractories used. Again, better refractories, slag-composition

control by dolomite, and improved process control have increased refractory

lifetime. Furthermore, the basic-oxygen steelmaking refractories are

based on periclase (domestically produced from brine or seawater) with

carbon from pitch or amorphous sources. These changes have reduced the

steel industry requirements for chrome-ore refractories.

In electric furnace steel making, the trends are again toward

extensive use of water-cooled panels, and the remaining refractories

are based on periclase with graphite and carbon. Usage of refractories

in the AOD furnaces is also declining due to improved materials and

blowing practices. Both dolomite (with excellent quality deposits in

the U.S) and periclase-chrome are used. In the event of a chromite

shortage, dolomite could become the exclusive refractory used in AOD.

Improved refractories are also used in ladles, tundish and flow

control systems. Fireclay and fireclay-graphite in ladles are being

replaced by high-alumina or basic (dolomite, periclase-chrome, periclasecarbon) refractories in order to improve steel cleanliness. This

29 bauxite is imported because domestic bauxite is unsatisfactory for

the production of the high purity material required in these steels .

Tundish and tundish flow control systems in continuous casting use

high-alumina liners and periclase consumable liners. The important

trend here is to control formation of Al^O^ inclusions, by reduction of

silica, which can plug passages as well as adversely affect properties.

19
Import Implications of Advanced Technical Developments

The increased performance and yields common to the technologies

described above will tend to lower dependence on imports generally.

One concrete example of the magnitude of the changes that can be expected

is the drop in the fraction of refractories used in the United States

that is required by the steel industry. This drop of up to 20% is a

measure of the suddenness with which such technological changes can occur

when economically attractive technical opportunities appear.

Countering this trend, however, is a trend toward alloy steels.

Another rapid change in import demand, but in the opposite direction,

is that for South African high-carbon ferrochromium. The argon-oxygen

decarburization process has increased the ability of steel makers to

use this high-carbon ferrochromium. Simultaneously, the increase in

transportation and energy refining costs have made the processing of

2 31 ferrochromium in southern Africa more cost effective ’

. The result

has been an increase in the southern Africa's share of the world market

2

in ferrochromium from 15% to 37% between 1970 and 1979 . Although

this dependence on a localized ferrochromium source is not expected to

2 continue to increase further in the near future , the prognosis over a

period of 25 to 50 years is that the entire world will be dependent for

. 32

its chromium entirely on southern Africa .

The final balance between the decreased dependence by the steel

industry on imported chromium generally, and the increased dependence

on southern Africa specifically, is not quantitatively clear at this

point. What is clear is that an increase in the availability of technical

options will necessarily become more important as the dominance of a

single supply region in the ferrochromium market increases.

20
Recycling

The use of recycling in the steel industry varies widely from

sector to sector. Mini mills use scrap exclusively as their source of

starting material* . However, the fraction of raw materials requirements

supplied by scrap for the integrated mills in 1981 was substantially

12

less than half, or 48 million tons . Since plants both in the U.S.

and in West Germany have operated on charges made up completely of

scrap, utilization of scrap in this country could double, in principle.

Increased use will be facilitated by increased capability for electric

furnace melting.

The extent of the use of scrap depends on action at two distinct

points in the materials cycle. The first is the generation of "prompt"

scrap in the production process, either in the "home" plant or elsewhere.

The second is the return of "obsolete" scrap to the producer after use

by the consumer.

The extent of recycling of "home" scrap can be completely an

internal matter in an individual company. The economic utilization of

this "home" scrap is frequently facilitated by the establishment of a

system for segregation of the scrap close to its generation. By such

segregation, reprocessing costs may be made much lower than those

required if scrap from a number of sources either "prompt" or "obsolete"

is mixed. There is therefore typically an "induction period" for the

establishment of more effective utilization of home scrap. However,

this system is at the discretion of the local plant management.

Current utilization of home scrap by the steel industry varies

strongly according to the type of steel produced. There are two major

factors in this variation, the amount of scrap generated in the process,

21
and the requirements imposed by purchasers, who may demand that only

virgin material be used. Recycling of home stainless steel scrap

2 recovers only nine percent of total demand , largely because relatively

little scrap is generated in production. Recycling of home scrap in

the production of aircraft engines recovers only 60 percent of the much

larger fraction of superalloy scrap produced. As the yield of processing

technologies increases, the amount of scrap available will fall off.

For example, the improvements that are foreseen in the basic-oxygen

furnace yields suggest that this technology will no longer be self

12 sufficient in the production of home scrap and will be able to utilize

prompt scrap from other sources.

The areas that have been identified as primary candidates for

increased attention in recycling are fume, dust, and slag generation in

5 addition to improved segregation . The Bureau of Mines is developing

2 technology to facilitate this recovery .

The challenge in increasing the recycling of obsolete scrap is

perhaps greater. A major hurdle in meeting this challenge is the

12 establishment of a collection mechanism . Another hurdle is the

assignment of the substantial risk involved. The extent of recycling of

both types has proved to be highly sensitive to the price of competing

raw materials.

22
SUBSTITUTION

This section addresses substitution as a means of conserving

critical materials used in steel making. As noted above U.S. supplies

of chromium, manganese, cobalt, and columbium are of major importance

to the steel industry and are not commercially available from domestic

sources.

33

For columbium, there are already alternatives , including vanadium

and molybdenum for high strength low alloy steels, and titanium and

tantalum in stainless steel. However, some of these may involve a cost

34

or performance penalty .

Cobalt use in steels is primarily in tool steels and represents

less than 10 percent of U.S. cobalt consumption. Two cobalt-free tool

steels are commercially available. These are based on a powder process

35 involving hot isostatic pressing . This and other substitution

options for cobalt were reviewed in a public workshop on aerospace

material s^.

For manganese in steel, a number of technically feasible alternatives are known including nickel, molybdenum, and chromium. However,

the very large amounts of material required to substitute for the 15 lbs

of manganese required per ton of raw steel would disrupt the supply and

37 delivery patterns of alternative alloying elements .

Chromium use in steel represents over 60 percent of U.S. demand for

chromium. Within the industry, use is concentrated in alloy and stainless

steels. Stainless and alloys steels account for about 1 and 10 percent,

respectively, of total U.S. steel production, and yet these sectors alone

consume 250,000 to 300,000 short tons of chromium per year. Because of

23
its availability and low cost, research in chromium alternatives has not

been pursued as thoroughly as for other alloying elements. However, a

number of substitutes exist. This section reviews alternatives to chromium

in steel, both available technologies and opportunities for new alternatives.

Chromium Functions in Steel

Chromium is used in stainless steels to impart corrosion resistance,

. 32 oxidation resistance and to contribute to stabilization of austenite .

Chromium is required also for strength in structural steels, especially in

high temperature applications; for high fatigue resistance in ultrahigh

38 strength steels and for hardenabi 1 i ty . Chromium provides these

properties inexpensively. Based on a long history of experimentation

and evaluation chromium is therefore frequently the cost effective

choice where any of these properties or a combination of them are

required. However, for many applications other materials without

chromium are either commercially available or appear feasible. For

32

corrosion resistance, no element is known to be comparable to chromium .

However, chromium content in austenitic stainless steels can be reduced

below the traditional 18 percent without impairing corrosion resistance

in many applications.

Substitution Options for Chromium in Corrosion and Oxidation

Resistant Stainless Steels

Stainless steels for corrosion and oxidation resistance represent

the largest single use of chromium, about 50 percent of U.S. demand for

chromium and 70 percent of the chromium used in steel. One stainless

24
steel grade alone, type 304, accounts for approximately 40 percent of

total U.S. chromium consumption. Important uses of stainless steels

are in the automotive (exhaust systems) and aircraft (ducting and

tubing) industries. Stainless steels are also used throughout the

construction, mining, and manufacturing sectors; major critical uses

are in equipment for chemical processing, for oil exploration and

drilling, and for electric power (coal and nuclear) generation. For

oil country tubular goods which are used in high pressure, high temperature environments including exposure to sulphur, the use of chromium

39

steels is increasing . Although austenitic stainless steels contain

18 percent or more chromium, for corrosion resistance, passivity is

achieved with 12 percent chromium and for most applications this amount

will provide adequate corrosion resistance. Chemical industry applica-

. . 32 tions may be exceptions . The function of chromium in these steels as

an austenite stabilizer can be performed as well by manganese so that

in an emergency the chromium content of replacement steels could be

reduced to 12 percent or lower. Such changes demand careful evaluation

40

of the service requirements for the particular applications . For

example, austenitic steels with 14 percent as opposed to the traditional

18 percent chromium have oxidation resistance and adequate strength for

1400 °F service^. A 9Cr-lMo steel modified by small additions of Nb

and V is being tested as a replacement for 18Cr steels in steam power

21 42-43

plant heat exchangers ’. New higher strength duplex stainless

steels and higher corrosion resistance (superferritic) steels can lower

total chromium demand by requiring 50 percent reduced cross-section

40 sizes although their chromium levels are higher .

Replacement of chromium in stainless steel with aluminum and/or

silicon is considered feasible in some oxidation resistant applications

25
26 in absence of such corrosive compounds as . Sometimes development

of these new alloys is facilitated by development of new technologies

• 44 such as rapid solidification processing (RSP) . An example of this is

a series of new Fe

3

Al plus dispersoid rapidly solidified alloys which

have significantly improved cyclic oxidation resistance at 1100 °C

. 45 compared with AISI 347 stainless steel and Haynes 188 alloy . In another

project aluminum steels (Fe-8Al-6Mo) are being developed which have

demonstrated high temperature air oxidation resistance superior to that

32 of type 304 stainless . The cost of these alternative alloys however

is likely to remain higher than the cost of stainless steel.

Some research has been undertaken on the intermetal 1 ic nickel

aluminides as possible substitutes for austenitic high chromium steels

in structural applications for elevated temperature, corrosive/oxidizing

environments. These materials are currently not promising because of

great difficulty in processing although progress has been reported in

46 reducing the inherent brittleness of Ni^Al by microadditions of boron .

Need for further work on the low ductility of the intermetal 1 ics would

be required in order to utilize their high temperature strength and

chemical stability for chromium conserving applications.

Silicon added to iron or nickel also imparts excellent resistance

to aqueous corrosion; the alloys are brittle however and commercially

available only as casting. Exploitation of silicon alloys as a more

general corrosion resistant substitute requires research to improve

their mechanical properties^

Development of new alloys without chromium is also underway:

Iron-manganese-aluminum alloys are being developed to substitute for

austenitic Ni-Cr stainless grades in heat resistant applications at

moderate temperatures and corrosion resistant applications in some

26
47 environments . Although they are brittle, they have already been used

48 successfully in furnace and ocean environment . Nickel-copper and

nickel-molybdenum alloys may also be used with some sacrifice of

21 mechanical properties and corrosion resistance . Silicon-molybdenum

ductile iron has performed more effectively than high chromium steels

in high temperature corrosive-erosive environments such as furnace

49

grates and exhaust manifolds .

Other alternatives to stainless steels in some corrosive environments

are nickel, titanium, tantalum, ceramics and glass, and electroless

nickel coatings. These are used now wherever they are economically

attractive. Plastics and composites (e.g., fiber reinforced plastics)

may possibly provide options to replace some stainless steel in corrosion

resistant chemical processing equipment. The elimination of problems

inhibiting wider use of plastics and composites is seen as one fruitful

27 research area .

As previously noted, cladding and coating are important options

for reduction of chromium use where its primary function is to provide

23 40 surface protection from corrosion, oxidation, and/or wear ’

. The

25 technology for cladding stainless steel is well established , and

since it has been demonstrated to reduce chromium requirements by 10 to

20 percent in currently economical applications it is an important

conservation option for chromium. A substantial fraction of the stainless

steel plate market (up to 200,000 tons), could be replaced by clad

3 plate, saving the order of 30,000 tons of chromium per year .

Other successful examples of this approach that could reduce

chromium demand and in some cases improve corrosion, wear and fatigue

24 26

performance are electroless nickel and nitriding . They are widely

27
used now where cost effective and could be used more widely for wear

and corrosion protection if chromium were unavailable.

Electrodeposition can be adapted to surface alloy coatings. It

allows application of relatively large amounts of material to the

surface and can be accomplished at room temperatures without affecting

previous heat treatments of the substrate. An important variant of

electrodeposition, pulsed electrodeposition uses a pulsed dc current

typically a square wave form and produces dense, unusually fine-grained

or amorphous deposits of high purity.

Alloying elements may be diffused into the metal by applying a

powder to the surface at elevated temperatures. For example, it is

estimated that "chromized steel sheet", 0.002" thick 25 percent chromium,

diffusion bonded coating on low carbon sheet steel may be used as a low

chromium alternative to ferritic stainless steel in special applications.

Ion implantation, a relatively new technique for surface treatment

of metals, is a low temperature process that is easily controlled

through electrical signals and is applicable to all elements. With ion

implantation new metallurgical phases can be produced, including amorphous

or glassy phases. It is now limited to applications where thin coatings

are acceptable.

The latter two approaches may be used separately or in combination

with surface melting, usually by laser or high energy electron beams to

23

produce new alloys or to reduce concentration gradients near the surface

For special applications such as power turbines requiring high

temperature strength, erosion and corrosion resistance, and machine

tools requiring hardness and wear resistance, silicon based ceramics

are potential alternatives to chromium containing steels and superalloys.

28
The key problems are brittleness and fracture susceptibility; these may

be solved by sophisticated design combined with successful research

leading to microstructure/processing advances.

Substitution Options for Chromium in Structural Alloy Steels

Chromium is also used extensively as an alloying element to provide

hardenabil ity in a wide variety of steel grades. Altogether this use

3 50-51

accounts for about 20 percent of U.S. chromium consumption ’

Other alloying elements such as manganese and molybdenum are even more

effective hardenabi 1 ity agents, and in many instances appropriate

commercial alternatives are already well developed"^ For many heat

treatable steel applications, chromium free or low chromium alloys are

commercially available. Other potential replacements are in development.

Computerized models are being used to identify optimum alloy compositions

for specific applications where individual alloy element composition is .... .38,50,52 guided by cost * *

.

Carburizing steels for high temperature applications requiring

case hardness and toughness may contain up to 5 percent chromium.

However, the precise role chromium plays is not known and chromium free

alternatives have not been identified. Based on successful development

of alternatives for lower temperature service, prospects for developing

52 chromium free carburizing steels are very promising .

For high carbon steels (AISI 52100) used for ball bearings, alternatives have been developed with chromium content reduced from 1.45

percent to 0.5 percent. These have received wide customer acceptance

41

in bearing applications .

29
Industrial research and development efforts have led to modified

"commercial bar" alloys with no chromium and with suitable heat treatment

38 characteristics and mechanical properties . Chromium-free steels are

also commercially available in structural plate and abrasion resistant

plate categories. In addition, computer models for predicting hardenability, properties, and heat treatment requirements are now available

to facilitate development of new alloys such as weathering steels.

These are being applied, for example, in a Bureau of Mines supported

project to develop two chromium-free steels as cost effective replacements for two AISI-SAE standard alloy series (8600 and 4100). These

alloys are construction grades containing 0.8 to 1.1 percent and

0.4 to 0.6 percent chromium, respectively, and account for approximately

50-51

10 percent of the total U.S. chromium consumption

HSLA steels have been used to meet a combination of strength,

. 43 toughness, and weldability requirements for pipeline service and for

fuel saving weight reductions in the transportation industry. The

strength of these steels does not depend on traditional hardenabi 1 ity

approaches and the majority do not contain chromium^. They constitute

a new class of steels with good strength, toughness, and formability.

This has been achieved as a result of applying advances in understanding

of processing/microstructure/property relationships; i.e., by using

micro additions (less than 0.1 percent of key alloying elements) and

controlled thermomechanical treatments'^. The use of these steels may

53

be expanded to supplant chromium-containing heat treatable steels .

For most structural steel grades chromium-free substitutes are

available or substitution technology appears adequate. Indeed, such

2

changes are already being made in the automotive industry . Two

exceptions are pressure vessel plate steels and ultrahigh strength

30
steels. Annual U.S. consumption of ASTM A- 387 steel grades used for

pressure vessels, boilers, and heat exchangers is 8000 to 9000 tons.

The common grades contain either 1.25 percent or 2.5 percent chromium

which is required for high temperature strength, toughness, and resistance to hydrogen and elevated temperatures. There are no known chromium

free substitutes. Ultrahigh strength steels used for aircraft landing

gear all contain 0.8 to 1.00 percent chromium; no chromium free alternatives with adequate strength and fatigue resistance are known. For

chromium conservation in both of these areas research is required..

38

None is currently underway .

31
INSTITUTIONAL FACTORS

Sped fi cations

Steel spedfications--formal ized agreements on compositional

limits, reached by independent standards organizations, trade associations or professional societies involving sellers and buyers, etc.

may be a practical barrier to materials conservation in certain cases.

Some specifications are imposed to assure properties directly, while

others are associated with particular processing needs. When processes

change some chemical specification can be lowered. A significant

manganese conservation opportunity—possibly capable of saving 25

percent of current consumption—consists in bringing traditional manganese

specifications in standard carbon steels into line with current low

sulfur levels. The practice of using stainless grades with chromium

concentrations up to twice that needed for corrosion resistance in

service was mentioned previously. This problem is avoided generally

when customers specify operational performance, and producers are free

to determine the chemistry appropriate to the specified performance and

5 their processing requirements .

Qua! ification

The use of specific materials for certain areas that are safetyor defense-related is controlled by qualification through testing with

approved procedures that simulate use. Materials used in the nuclear,

power boiler and pressure vessel, and aerospace industries, especially

aircraft engines, are generally covered by such qualification requirements.

32
These qualification tests are generally both lengthy and expensive.

They therefore inevitably tend to discourage innovation in materials

39 use . Manufacturers in areas that cater to the private sector would

sometimes prefer to ease qualification procedures to permit more rapid

and less expensive innovation. Regulations governing qualification in

these areas could usefully be reviewed in order to streamline qualification procedures.

Composition of the National Defense Stockpile

The technological advances described in the foregoing sections of

this chapter are bringing about two pronounced changes in the raw

materials requirements of the steel industry and those industries on

which it depends for supply. These have implications for the National

defense stockpile. The first change is in the general impurity level

of the raw materials used in steel production; the second change is in

the form of chromium imported for ultimate use by the steel industry.

The trend toward clean steels has led to a demand for purer raw

materials. There is a particular desire to avoid unnecessary sulfur.

Materials in the stockpile in general were purchased before these

changed requirements and therefore are known or assumed to be less pure

than what is now used in production.

On the other hand, the duplex processing procedures noted previously

are able to remove such impurities. Where a number of impurities are

present at levels higher than desired, more elaborate processing may be

required than would be necessary for high quality raw materials.

Nevertheless, the stockpile materials are generally believed to be

33
useable with increased processing cost. In the event of a curtailment

in steel raw materials, clean steels could be made via ladle metallurgy

from the materials in the stockpile.

The prognosis for the country's ability to cope with a related

stockpile question is not so bright, however. The rapidly increasing

economic advantages of ferrochrome production in southern Africa are

leading the industrialized countries of Europe, Asia, and the Americas

to shift dramatically the types of material that they are importing.

Ferrochromium imports are replacing the importation of chromite ore.

We are thus losing our ability to process chromite ore into ferrochromium, and our stockpiles of chrome ore are therefore rapidly

2 decreasing in utility for the emergency for which they were designed .

The relative balance of different chromium-containing raw materials

in the national defense stockpile need to be reexamined. Steps to do

so have been initiated by the Department of Commerce in conjunction

with the Federal Emergency Management Agency, the General Services

Administration, the Department of the Interior, and the Department of

Defense.

Research

The technical developments that will affect the use of chromium in

most instances represent opportunities that will require research to

realize. The research required is of two distinct types: short and

long range. The types of technical problems addressed, the motivation

for this activity, and thus the relative roles of private and public

sectors differ markedly in the two cases.

34
Short term research is directed toward immediate problems that

require qui dance from particular research results for rapid application

on the production line. The private sector has an incentive to carry

out materials research where it is needed to improve immediately the

productivity of a production process or utilization by manufacturing

industries. Where pressing needs develop, such as the need for highly

corrosion resistant materials for use in hydrogen sulfide atmospheres, ... . 39 research has been initiated by the private sector . Rapid increase in

the price of a raw material also will create such an incentive, and the

response to the recent rapid increase in cobalt prices confirms this

observation. Cobalt-free commercial alternatives to the use of cobalt

in high speed tool steels were successfully developed and have given

35 performance superior to that provided by cobalt .

However, chromium and manganese are so relatively low in cost that

cost effective alternatives have not been found. The continued low

cost of these materials has not provided a strong incentive to continue

the search for cost-effective alternatives in steel. Since the

possibility of the loss of chromium supplies is relatively remote, the

private sector has not made the investment in a continuing search for

proven alternatives. Should access to chromium be lost suddenly,

severe price and supply dislocations in the steel industry and

industries that use steel would occur as they did in the recent markets

for cobalt. Even in cases where relevant research has been carried

out, it may be proprietary and hence not widely available1 "^. The

Federal Government is the only source of assured support for publicly

available research results that can mitigate in advance severe price

32 fluctuations in the event of a supply loss

35
Investment in the proper long range research can help assure the

achievement of the basic understanding essential to the satisfactory

replacement of imported elements in existing alloys in the long run.

Such research leads to alternatives with superior performance. However,

long-term research is inherently expensive and is usually supported by

Federal funding as well as by funding by industries with a large research

base. Because the commercial incentive for such research is less

immediate and because the benefits are frequently so fundamental that a

single firm alone cannot recover research costs, the rationale for

2 38 43 Federal funding is much stronger here than for short term research ’ ’

Examples of longer-term research that might affect the need for chromium

50

and manganese are the effects of chemical composition on toughness

and the associated effects on toughness of lower levels of sulfur and

oxygen obtainable through ladle metallurgy. The potential for the

52 development of chromium-free carburizing steels is promising . The

replacement of chromium in stainless steel is another area of major

importance.

36
CRITICAL MATERIALS AND PRODUCTIVITY

The preceding sections of this chapter have described the technical

changes that are taking place in the steel industry. Those parts of

the U.S. industry that have been able to make the necessary investment

in new technology^, have remained relatively competitive. The preceeding

sections have also reviewed the influence that technological changes in

the steel industry and in materials science more broadly are having on

the raw materials requirements of the steel industry. These changes

increase the elasticity of demand for specific raw materials by increasing

54

the number of alternatives .

In some cases such alternatives such as clean steels will be

technically superior and cost-effective at present prices. These will

tend to decrease the demand for imported raw materials both through

improved performance, and through higher yields in processing. In

other cases, alternative technologies will remain either technically

disadvantageous or less cost-effective. Nevertheless, such technologies,

if available, can mitigate any curtailment of supplies or escalation in

priced

The establishment of technical alternatives to current technology

is therefore an important key both to increasing national productivity

55

and to greater independence of foreign raw materials supplies . Technical

alternatives differ from strategic supply options. The other essential

aspects of our comprehensive national strategy, such as stockpiles,

play the role of an insurance policy. They would be critically important

in an emergency, but only then. By contrast, technological alternatives

37
can pay off whether or not a material supply emergency occurs. Indeed,

technical alternatives can make the possibility of such an emergency

less likely.

As detailed in this chapter, the question of critical materials in

the manufacture of iron and steel products has been reviewed from many

angles, including the effect of process technology, recycling and

resource recovery, substitution and various types of new technology.

The main conclusion from this review is that, from a technical viewpoint,

the most potent factor for diminishing critical material problems is a

healthy domestic steel industry pursuing the research and capital

formation required for the introduction of leading technology and

modernization on a continuing basis. This conclusion rests on the fact

that, through the introduction of new technology for processing, for

recycling, and for achieving future requirements in respect to product

properties, the amount of critical materials required can be progressively

reduced through the more discriminating utilization of alloying elements.

The resulting steels will perform better, have more uniform quality,

and will cost less. We anticipate that chromium and manganese, because

of their relatively low cost, will continue to be used and therefore

continue to be the materials of greatest concern to the steel industry.

In many, perhaps most cases, however, alternatives are available, albeit

at substantially higher expense. Changes in cost structure are therefore

far more likely than total loss of material capable of performing

essential functions in our economy. Research, by providing improved

alternatives, can mitigate the possible swings in price and the

severity of loss of supply.

38
REFERENCES

1. American Iron and Steel Institute, "Steel 1981"

2. Bement, Arden L. , "Technical Aspects of Critical Materials Use by

the Steel Industry Vol. II," NBSIR 83-2679-2

3. National Materials Advisory Board Report 335, "Contingency Plans

for Chromium Utilization", 1978

4. Dennis, William E. , Remarks delivered at the Public Workshop,

"Trends in Critical Materials Requirements for Steels of the Future;

Conservation and Substitution Technology for Chromium," Vanderbilt

University, October 4-7, 1982

5. Geiger, Gordon H. , Vol. II this report, see reference 2

6. Richmond, Frank M. , Testimony before the Subcommittee on Oversight

and Investigations, Committee on Energy and Commerce, U.S. House

of Representatives, April 23, 1982

7. Shao, Maria, Wall Street Journal, November 24, 55 (1982)

8. Moore, J. J. , J. Metals, June, 39 (1982)

9. Robinson, George H. , Vol. II this report, see reference 2

10. Wright, Peter H. , Vol II this report, see reference 2

11. O'Neil, Dennis B. , Vol II this report, see reference 2

12. Cutler, Herschel , Vol II this report, see reference 2

13. K. K. Kappmeyer, private communication

14. Chandler, Harry E. , Baxter, Donald F. , & Kruger, Leonard G. , Metal

Progress, January, 220 (1982)

15. Cordy, James T. , Vol II this report, see reference 2

16. March, Eugene A., quoted in Metal Producing, January, 46 (1982)

17. Korchynsky, Michael, Paper delivered at the Public Workshop "Trends

in Critical Materials Requirements for Steels of the Future;

Conservation and Substitution Technology for Chromium," Vanderbilt

University, October 4-7, 1982

18. Brunner, Lewis, Vol II this report, see reference 2

19. National Bureau of Standards & Battel le Columbus Laboratories,

"The Economic Effects of Fracture in the United States," in press,

1982

20. "Process Control Sensors for the Steel Industry," sponsored by the

American Iron and Steel Institute, the Defense Advanced Research

Projects Agency, and the National Bureau of Standards, July 22-28,

1982

21. Asphahani , Aziz I., Vol II this report, see reference 2

22. Gaugh, Robert R. , Vol II this report, see reference 2

23. Moore, Peter G. , Vol II this report, see reference 2

24. Duncan, Ronald N. , Vol II this report, see reference 2

25. Skelly, James T. , Vol II this report, see reference 2

26. Wood, William G. , Vol II this report, see reference 2

27. Kachik, Edward A., Vol II this report, see reference 2

28. Hubble, David E. , & Kappmeyer, K. K. , Vol II this report,

see reference 2

29. Regan, R. J. , Iron Age, 221(10), 30-33 (1978)

30. Joseph, Robert W. , private communication

31. Rawlings, J. W. , Conference sponsored by Business Week and Aviation

Week, October 30, 1981

39
32. Lula, R. A., and Bangaru, R. , Vol II this report, see reference 2

33. National Material Advisory Board Report 391 "Tantalum and Columbium

Supply and Demand Outlook," 1982.

34. U.S. Bureau of Mines, Mineral Commodity Summaries, 1982

35. Haswell, W. T. , "Conservation and Substitution Technology for

Critical Materials, NBSIR 82-2495, Vol. I, Paper No. 16

36. "Conservation and Substitution Options for Critical Materials,"

Vanderbilt University, June 1981

37. National Materials Advisory Board Report 374, "Manganese Reserves and

Resources of the World and Their Industrial Implications," 1981.

38. Ault, R. T. , Vol II this report, see reference 2

39. Kochera, John W. , Vol II this report, see reference 2

40. Houze, Gerald L. , Jr., Vol II this report, see reference 2

41. Jatczak, C. F. , Vol II this report, see reference 2

42. Sikka, Vinod K. , Vol II this report, see reference 2

43. Heger, James J. , Vol II this report, see reference 2

44. Simenz, Rod F. , Vol II this report, see reference 2

45. "Third Conference on Rapid Solidification Processing: Principles

and Technologies," sponsored by the Defense Advanced Research Projects

Agency, the Office of Naval Research, the Army Research Office,

Air Force Wright Aeronautical Laboratory, and the National Bureau of

Standards, December 6-7, 1982

46. Liu, C. T. , and Koch, C. C. , Vol II this report, see reference 2

47. Banerji, Samir K. , Vol II this report, see reference 2

48. Wang, R. , and Rapp, R. A., Vol II this report, see reference 2

49. Janowak, Jay, Vol II this report, see reference 2

50. Breen, Dale H. , Vol II this report, see reference 2

51. Keith, Carl J. , Vol II this report, see reference 2

52. Diesburg, D. E. , Eldis, G. T. , and Lander, H. N. , Vol II this

report, see reference 2

53. Jones, Brian L. , Vol II this report, see reference 2

54. Swager, William, private communication

55. Gray, Allen G. , Vol II this report, see reference 2

40
U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publication Date

SHEET (See instructions) NBSIR 83-2679-1 April 1983

4. TITLE AND SUBTITLE

Technical Aspects of Critical Materials Use by the Steel Industry

Volume I: Summary Report

5. AUTHOR(S)

R. Mehrabian, J. McKinley, B. Steiner and K. Bhansali

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City. State. ZIP)

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bl iography or literature survey, mention it here) This report reviews technical opportunities for research in process

improvement and in alternative materials development that would reduce

U.S. dependency in critical materials.

The advanced technologies reviewed here, in addition to their

implications for critical materials conservation represent trends

leading to better quality, lower cost steel products, and therefore

they may contribute positively to the industry's more immediate

concern for improved markets.

O The Summary Report draws extensively on material presented at a public

workshop sponsored jointly by the National Bureau of Standards, Bureau

of Mines, Army Research Office, and Vanderbilt University. The worksho

"Critical Materials Requirements for Steels of the Future; Conservation

and Substitution for Chromium," was held at Vanderbilt University,

October 4-7, 1982; it featured 44 presentations by technical authoritie

from steel producing and using industries. This material is presented

in Volumes II A, and II B.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Advance coatings; alternative materials; chromium; processing; steel;

strategic materials.

13.

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~31 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

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