30079_04.pdf

CHAPTER 4

COPPER AND ITS ALLOYS

Howard Mendenhall

OHn Brass

East Alton, Illinois

Robert F. Schmidt

Colonial Metals

Columbia, Pennsylvania

4.1 COPPER

4.2.1 Introduction

4.1.1 Composition of Commercial

Copper

4.2.2 Selection of Alloy

4.2.3 Fabrication

4.1.2 Hardening Copper

4.2.4 Mechanical and Physical

Properties

4.1.3 Corrosion

4.1.4 Fabrication

4.2.5 Special Alloys

4.2 SAND-CAST COPPER-BASE

ALLOYS

4.1 COPPER

Howard Mendenhall

4.1.1 Composition of Commercial Copper

Specifications for copper, generally accepted by industry, are the ASTM standard specifications. These

also cover silver-bearing copper. (See Table 1)

Low-resistance copper, used for electrical purposes, may be electrolytically or fire refined. It is

required to have a content of copper plus silver not less than 99.90%. Maximum permissible resis-

tivities in international ohms (meter, gram) are: copper wire bars, 0.15328; ingots and ingot bars,

0.15694.

Mechanical Properties of Copper

Cold Rolled

Annealed

or Drawn

Cast

Tensile strength

psi

30,000-40,000

32,000-60,000

20,000-30,000

MPa

210-280

220-400

140-210

Elongation in 2 in.

25-40%

2-35%

25-45%

Reduction of area

40-60%

2-4%

—

Rockwell F hardness

65 max

54-100

—

Rockwell 3OT hardness

31 max

18-70

—

Mechanical Engineers' Handbook, 2nd ed., Edited by Myer Kutz.

Physical Properties of Copper

0.323 lb/in. 3

1981 0 F

0.0000094/ 0 F

8.94 g/cm 3

1083 0 C

0.0000170/ 0 C

Density

Melting point

Coefficient of linear

thermal expansion

(68-212 0 F)

(20-10O 0 C)

(68-392 0 F)

(20-20O 0 C)

0.0000097/ 0 F

0.0000174/ 0 C

(68-572 0 F)

(20-30O 0 C)

0.0000099/ 0 F

0.0000178/ 0 C

1 A in. /ft

226 Btu/ft 2 /ft/hr/°F

at 68 0 F

10.3 ohms (circular mil/ft)

at 68 0 F

0.023 ohms/°F

at 68 0 F

Pattern shrinkage

Thermal conductivity

398 W/m/°C

at 27 0 C

1.71 microhm/cm

at 2O 0 C

0.0068/ 0 C

at 2O 0 C

0.386 J/g/°C

at 2O 0 C

Diamagnetic

Selectively reflecting

119,30OMPa

Electric resistivity

Temperature coefficient

of electric resistivity

Specific heat

Magnetic property

Optional property

Young's modulus

17,300,000 psi

ASTM Specification B216-78, Fire-Refined Copper for Wrought Products and Alloys, calls for

the following analysis: Cu + Ag, min 99.88%; As, max 0.012%; Sb, max 0.003%; Se + Te, max

0.025%; Ni, max 0.05%; Bi, max 0.003%; Pb, max 0.004%.

Oxygen-free high-conductivity copper is a highly ductile material, made under conditions that

prevent the entrance of oxygen and the formation of copper oxide. It is utilized in deep-drawing,

spinning, and edge-bending operations, and in welding, brazing, and other hot-working operations

where embrittlement must be avoided. It has the same conductivity and tensile properties as tough

pitch electrolytic copper.

Deoxidized copper containing silver has been utilized to increase softening resistance of copper.

It does not affect oxygen level. A number of elements that reduce oxygen in copper, such as Zr, Cr,

B, P, can also provide some softening resistance.

4.1.2 Hardening Copper

There are three methods for hardening copper: grain-size control, cold working, or alloying. When

copper is hardened with tin, silicon, or aluminum, it generally is called bronze; when hardened with

zinc, it is called brass.

4.1.3 Corrosion

Copper is resistant to the action of seawater and to atmospheric corrosion. It is not resistant to the

common acids, and is unsatisfactory in service with ammonia and with most compounds of sulfur.

Manufacturers should be consulted in regard to its use under corrosive conditions.

4.1.4 Fabrication

Copper may be hot forged, hot or cold rolled, hot extruded, hot pierced, and drawn, stamped, or spun

cold. It can be silver-soldered, brazed, and welded. For brazing in reducing atmosphere or for welding

by the oxyacetylene torch or electric arc, deoxidized copper will give more satisfactory joints than

electrolytic or silver bearing copper. High-temperature exposure of copper containing oxygen, in

reducing atmosphere, leads to decomposition of copper oxide and formation of steam with resulting

embrittlement. Copper is annealed from 480 to 140O 0 F, depending on the properties desired. Ordinary

commercial annealing is done in the neighborhood of UOO 0 F. Inert or reducing atmospheres give

best surface quality; however, high temperature annealing of oxygen-containing coppers in reducing

atmosphere can cause embrittlement. Copper may be electrodeposited from the alkaline cyanide

solution, or from the acid sulfate solution.

4.2 SAND-CAST COPPER-BASE ALLOYS

Robert K Schmidt

4.2.1 Introduction

The information required for selection of cast copper-base alloys for various types of applications

can be found in Table 4.1. The principal data required by engineers and designers for castings made

of copper-base alloys are given in Table 4.2. A cross-reference chart is shown in Table 4.3 for quick

reference in locating the specifications applying to these alloys. Additional information in regard to

Table 4.1 Application for Copper-Base Alloys

Alloy

Number

C85200

C83600

C85400

C97400

C86200

C95400

C85200

C93200

C93800

C93700

C91300

C91000

C86300

C95400

C93700

C93800

C91300

C87200

C83600

C92200

C84400

C84800

C85200

C95400

Uses

Andirons

Architectural trim

Types of Alloys

Leaded yellow brass

Leaded red brass

Leaded yellow brass

Leaded nickel silver

Manganese bronze

Aluminum bronze

Leaded yellow brass

High-leaded tin bronze

Ball bearing races

Bearings, high speed,

low load

Bearings, low speed,

heavy load

Tin bronze

Manganese bronze

Aluminum bronze

High-leaded tin bronze

Bearings, medium

speed

Bells

Tin bronze

Silicon bronze

Leaded red brass

Leaded tin bronze

Leaded semired brass

Carburetors

Cocks and faucets

Leaded yellow brass

Aluminum bronze

Corrosion resistance to

acids

Leaded nickel bronze

Silicon bronze

Nickel aluminum

bronze

Leaded red brass

Leaded semired brass

Leaded red brass

Silicon bronze

Aluminum bronze

Leaded semired brass

Leaded nickel bronze

C97600

C87200

C95800

alkalies

seawater

C83600

C84400

C83300

C87200

C95400

C84400

C97600

C97800

C90700

C91600

C95400

C83600

C86200

C95300

C86300

C90300

C83600

C95400

C87200

C95400

C86500

C86200

C95800

C86500

C97800

C85200

water

Electrical hardware

Fittings

Food-handling equipment

Gears

Tin bronze

Aluminum bronze

Leaded red brass

Manganese bronze

Aluminum bronze

Manganese bronze

Tin bronze

Leaded red brass

Aluminum bronze

Silicon brass

Aluminum bronze

Manganese bronze

General hardware

Gun mounts

High-strength alloy

Impellers

Landing gear parts

Lever arms

Marine castings and

fittings

Aluminum bronze

Manganese bronze

Leaded nickel bronze

Leaded yellow brass

Marine propellers

Musical instruments

Ornamental bronze

Table 4.1 (Continued)

Alloy

Number

C95300

C90500

C91300

C84400

C84800

C90300

C93800

C95800

C92200

C92300

C92200

C92600

C83600

C84400

C97800

Uses

Pickling baskets

Piston rings

Types of Alloys

Aluminum bronze

Tin bronze

Plumbing fixtures

Leaded semired brass

Pump bodies

Tin bronze

Leaded tin bronze

Aluminum bronze

Leaded tin bronze

Steam fittings and

valves

Valves, high pressure

Leaded tin bronze

Valves, low pressures

Leaded red brass

Leaded semired brass

Leaded nickel bronze

Valve seats for elevated

temperature

Valve stems

Silicon brass

Silicon bronze

High-leaded tin bronze

C87500

C87200

C93700

C93800

C90700

C86500

All

grades

C87200

C95300

C95500

Wear parts

Weldability

Tin bronze

Manganese bronze

Aluminum bronze

Silicon bronze

Aluminum bronze

Welding jaws

Wormwheels

special alloys, such as high conductivity copper, chromium-copper, and beryllium copper, is covered

in Section 4.2.5.

4.2.2 Selection of Alloy

Table 4.1 is an outline of the various types of allows generally used for the purposes shown. When

specifying a specific alloy for a new application, the foundry or ingot maker should be consulted.

This is particularly important where corrosion resistance is involved or specific mechanical properties

are required. While all copper-base alloys have good general corrosion resistance, specific environ-

ments, especially chemical, can cause corrosive attack or stress corrosion cracking. An example of

this is the stress corrosion cracking that occurs when a manganese bronze alloy (high-strength yellow

brass) is placed under load in certain environments.

The typical and minimum properties shown in Table 4.2 for the various alloys are for room

temperature. The effect of elevated temperature on mechanical properties should be considered for

any given application. The ingot maker or foundry should be consulted for this information.

Since copper-base alloy castings are often used for pressure-tight value and pump parts, caution

should be exercised in alloy selection. In general, when small-sized, thin-wall castings are used, such

as valve bodies with up to 3-in. openings, with all sections up to 1 in., the leaded red brass and

leaded tin bronze alloys should be specified. When heavy-wall valves and pump bodies over 1-in.

thickness are used, the castings should be made of nickel aluminum bronze or 70/30 cupronickel.

These alloy preferences are based on differences in solidification behavior.

4.2.3 Fabrication

All sand-cast copper-base alloys can be machined, although some are far more machinable than

others. The alloys containing lead, such as the leaded red brasses, leaded tin bronzes, and high-leaded

tin bronzes, are very easily machined. On the other hand, aluminum and manganese bronzes do not

machine easily. However, use of carbide tooling, proper tool angles, and coolants permit successful

machining. In regard to weldability, no leaded alloys should be welded. In general, the aluminum

bronzes, silicon bronzes, and a-/3 manganese bronzes can be welded successfully. This also applies

Table 4.2 Sand-Cast Copper-Base Alloys

Mechanical Properties

Impact

Strength

(Izod)

(ft-lb)

Yield

Strength 3

ksi (MPa)

Tensile

Strength 3

ksi (MPa)

Elonga-

tion 3

(%)

Brinell

Hardness

(500 kg)

Electrical

Conductivity

(%, IACS)

Pattern

Skrinkage

(in. /ft)

UNS

Number

Ingot

Number

Nominal Composition (% by Weight)

Cu Sn Pb Zn

Others

C83600

C83800

C84400

C84800

C85200

C85400

C85700

115

120

123

130

400

403

405.2

14 (97)

13 (90)

12 (83)

11 (76)

14 (97)

16(110)

14 (97)

13 (90)

12 (90)

18 (124)

30 (207)

29 (200)

28 (193)

35 (241)

30 (207)

40 (276)

36 (248)

35 (241)

34 (234)

36 (248)

38 (262)

34 (234)

51 (352)

12*

15.2

16.7

16.6

18.6

19.6

21.8

11 X 64

3 Xl 6

7 X 32

37.3

0.3 Al

Zn Fe Al

Others

1 X 4

9 X 3 2

1 1 A

15 /64

180 C

225 C

W5 C

130 C

115 C

C86200

C86300

C86400

C86500

C87200

C87500

423

424

420

421

500

26 3

45 (310)

60 (414)

20 (138)

25 (172)

18 (124)

24 (165)

48 (330)

68 (469)

24 (165)

28 (193)

25 (172)

30 (207)

90 (621)

110(758)

60 (414)

65 (448)

45 (310)

60 (414)

96 (662)

119(821)

65 (448)

71 (490)

58 (400)

65 (462)

32*

7.4

8.0

19.3

20.6

6.1

5.9

6.1

26 3

58 38

0.75

0.25

0.75 Pb

39 1

4 Si

1 Mn, 4 Si

82 14

4 Si

Cu Sn Pb Zn

Others

225

210

245

230

215

315

305

319

C90300

C90500

C92200

C92300

C92600

C93200

C93700

C93800

18 (124)

16(110)

18 (124)

14 (97)

12 (83)

14 (97)

20 (138)

22 (152)

20 (138)

18 (124)

17(117)

16(110)

40 (276)

34 (234)

36 (248)

40 (276)

30 (207)

26 (179)

45 (310)

46 (317)

40 (276)

42 (290)

44 (303)

38 (262)

39 (269)

32 (221)

14*

19*

12.4

10.9

14.3

12.3

10.0

12.4

10.1

11.6

3 X 6

3 /16

3 Xl 6

7 /32

1 Xs

5 /32

88 10

4 1 X 2

6 I 1 X 2

87 10

80 10

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