Introduction

CARBON AND ALLOY STEELS, the most widely used metallic material, account for more than 80 million tons, or approximately 98% of the annual steel production in the United States (Table 1). Steels are a popular material of choice because they can be manufactured relatively inexpensively in large quantities to very precise specifications. They also provide a wide range of mechanical properties, from moderate yield strength levels (200 to 300 MPa, or 30 to 40 ksi) with excellent ductility to yield strengths exceeding 1400 MPa (200 ksi) with fracture toughness levels as high as 110 MPa 4m (100 ksi ).

Table 1 Net shipment of U.S. steel mill products--all grades

Steel products

1992

1991

Tons (a)

%

Tons (a)

%

Ingots and steel for castings

215

0.3

244

0.3

Blooms, slabs, billets

2,255

2.7

2,305

2.9

Wire rods

4,511

5.5

4,366

5.5

Structural shapes ( > 75 mm, or 3 in.)

5,081

6.2

5,245

6.7

Steel piling

454

0.6

430

0.5

Plates (cut lengths)

4,362

5.3

4,275

5.4

Plates (in coils)

2,740

3.3

2,667

3.4

Rails

Standard (over 27 kg, or 60 lb)

435

0.5

382

0.5

All other

5

0.0

16

0.0

Railroad accessories

122

0.1

89

0.1

Bars

Hot rolled

5,806

7.1

5,431

6.9

Bar-size light shapes

1,119

1.4

1,157

1.5

Reinforcing

4,781

5.8

4,859

6.2

Cold finished

1,458

1.8

1,341

1.7

Tool steel

64

0.1

51

0.1

Pipe and tubing

Standard pipe

1,062

1.3

970

1.2

Oil country goods

979

1.2

1,077

1.4

Line

1,110

1.3

1,439

1.8

Mechanical

790

1.0

744

0.9

Pressure

48

0.1

49

0.1

Structural

142

0.2

151

0.2

Pipe for piling

35

0.0

24

0.0

Stainless

32

0.0

34

0.0

Wire-drawn

900

1.1

865

1.1

Black plate

230

0.3

249

0.3

Tin plate

2,715

3.3

2,754

3.5

Tin-free steel

904

1.1

964

1.2

Tin-coated sheets

78

0.1

74

0.1

Sheets

Hot rolled

13,361

1.62

13,161

16.7

Cold rolled

12,692

15.4

11,532

14.6

Sheets and strip

Galvanized-hot dipped

8,199

10.0

6,910

8.8

Electrolytic

2,390

2.9

2,099

2.7

All other metallic coated

1,348

1.6

1,146

1.5

Electrical

436

0.5

458

0.6

Strip

Hot rolled

550

0.7

533

0.7

Cold rolled

832

1.0

755

1.0

Total Steel Mill Products

82,241

100.0

78,846

100.0

Carbon

76,625

93.2

73,480

93.2

Stainless

1,514

1.8

1,449

1.8

Alloy (other than stainless)

4,101

5.0

3,917

5.0

Source: American Iron and Steel Institute

(a) Thousands of net tons.

Following a brief review of the classification of steels, this article will review the following:

• Cleaning methods

• Finishing methods

• Conversion coatings

• Hot dip coating processes

• Electrogalvanizing

• Electroplating

• Metal cladding

• Organic coatings

• Zinc-rich coatings

• Porcelain enameling

• Thermal spraying

• Hardfacing

• Vapor deposited coatings

• Surface modification

• Surface hardening via heat treatment

Emphasis will be placed on the most commonly used methods for surface engineering of steels. No attempt is made at providing detailed information on any given process as this can be found in the cited articles found throughout this Volume. In terms of the coating, surface modification, and surface hardening processes described, the resulting property improvements (corrosion and/or wear resistance) will be stressed rather than the details of the process itself (equipment, plating bath compositions, process controls, etc.). Information on the surface engineering of stainless steels, tool steels, maraging steels, electrical steels, and ferrous powder metallurgy alloys can be found in the articles "Surface Engineering of Stainless Steels" and "Surface Engineering of Specialty Steels" which immediately follow in this Section of the Handbook.

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