Copper-Base Alloys Harold T. Michels Copper Development Assn., Inc., New York
C
ast copper alloys are known for their polished to a high luster, and plating, versatility. They are used in a wide soldering, brazing and welding also range of applications, such as plumbing are routinely performed; fixtures, ship propellers, power plant • large alloy choice, since several alwater impellers, and bushing and bearing loys may be suitable candidates for sleeves, because they are easily cast, have a any given application depending long history of successful use, are readily upon design loads and corrosivity available from a multitude of sources, can of the environment; achieve a range of physical and mechani• comparable costs to other metals due cal properties, and are easily machined, to their high yield, low machining costs brazed, soldered, polished or plated. and little requirement for surface coatFollowing is a list of physical and meings, such as paint. chanical properties common to cast copUsing Copper Alloys per alloys. Although not every property is Cast copper alloys are identified by applicable to every alloy, this range, which the Unified Numbering System (UNS) occurs in unique combinations, isn’t found in which each alloy is assigned a number in any other alloy group: ranging from C80000 to C99999 (Table • good corrosion resistance, which con1). From a metallurgical viewpoint, many tributes to its durability and long-term cast copper alloys are single-phase solid cost-effectiveness; solutions in which the alloying elements • favorable mechanical properties ranging such as zinc, tin and nickel, are substituted from pure copper, which is soft and ducfor copper in the copper matrix. Examples tile, to manganese-bronze, which rivals This CDA-955 aluminum-bronze jam nut of cast single-phase solution alloys are red the mechanical properties of quenched used in a drilling apparatus was produced brass, which contains up to 6% zinc and and tempered steel. In addition, almost via the permanent mold casting process. 2% tin, copper-nickel, which contains up to all copper alloys retain their mechanical 10% nickel, and tin-bronze, which contains properties, including impact toughness, mended feeds and speeds with proper up to 8% tin and 4% zinc. at low temperatures; tooling; As the alloy content increases, a second • high thermal and electrical conduc• ease of post-casting processing, as phase may form. In the case of brass, when tivity, which is greater than any metal good surface finish and high tolerthe zinc content is increased, a hard second except silver. Although the conductivity ance control is readily achieved. In phase (called beta) forms with the copperof copper drops when alloyed, copper addition, many cast copper alloys are rich matrix. This phase is found alloys with low conductivity still in yellow brass, which contains conduct both heat and electricup to 41% zinc. In addition, this ity better than other corrosionphase impairs room temperature resistant materials; ductility but increases elevated • bio-fouling resistance, as coptemperature ductility. per inhibits marine organism growth. Although this property Role of Lead (unique to copper) decreases Lead is commonly added to upon alloying, it is retained at a many cast copper alloys. Because useful level in many alloys, such of the low solubility of lead in as copper-nickel; • low friction and wear rates, copper, true alloying does not such as with the high-leaded occur to any measurable detin-bronzes, which are cast gree. During the solidification into sleeve bearings and exhibit of castings, some constituents lower wear rates than steel; in a given alloy form crystals • good castability, as all copper alat higher temperatures relative loys can be sand cast and many to others, resulting in tree-like can be centrifugal, continuous, structures called dendrites. The permanent mold and diecast; small spaces between the den• good machinability, as leaded drites can interconnect to form copper alloys are free-cutting micropores. This microporosity at high machining speeds, and is a consequence of the solidifimany unleaded alloys, such as cation process. The role of lead nickel-aluminum bronze, are Shown above is a nickel-aluminum bronze sailboat winch. This is to seal these intradendritic readily machinable at recom- alloy is especially desirable for fluid moving applications. pores. This results in a pressure-
36
ENGINEERED CASTING SOLUTIONS
2006 CASTING SOURCE DIRECTORY
This 1.5 meter valve for a municipal water works was produced in no-lead brass via green sand molding.
High copper alloys (more than 95.1% copper) are unique in that they combine high strength with high thermal and electrical conductivity. Chromium-Copper (C81400 to 81540)—Containing up to 1.5% chromium, the strength of these alloys is twice that of pure copper, but its electrical conductivity is 80% of pure copper. Applications include welding clamps and high-strength electrical connectors. Cop p e r- B e r y l l i u m ( C 8 2 0 0 0 t o C82800)—These alloys contain 0.352.85% beryllium as the major alloying element and are age- or precipitationhardened. They achieve high strength due to the precipitation of a fine second phase during heat treatment. Copper beryllium alloys either achieve high conductivity at moderate strength or moderate conductivity at high strength.
tight casting, which is important for fluid handling applications. Lead also allows the machining of castings to be performed at higher speeds without the aid of coolants because it acts as a lubricant for cutting tool edges and promotes the formation of small, discontinuous chips that can be cleared easily. This results in improved machined surface finishes. Lead also plays a role in providing lubricity during service, as in cast copper bearings and bushings. Lead does not have an adverse effect on strength unless present in high concentrations, but it does reduce ductility. Although lead-containing copper alloys can be soldered and brazed, they cannot be welded. Following is a list of the various cast copper alloy families and their property strengths.
Coppers Coppers (C80100 to 81200)—These alloys are pure copper (99.7% minimum) with traces of silver (for annealing resis-
Brasses tance) or phosphorus (a de-oxidizer for welding). These alloys are used in high thermal and electrical conductivity applications, such as electrical connectors. High Coppers (C81400 to C82800)—
The brasses (C83300 to C85800 and C89320 to C89940) are the most common casting alloys and are made of copper and zinc. Red Brass (C83300 to 83810)—The red brasses are alloys of zinc (1-12%) and tin
Table 1. Properties and Applications of Cast Copper-Base Alloys UNS Numbers
Properties
Applications
Coppers
Alloy Family
C80100 to C81200
soft, ductile, high electrical and thermal conductivity, good corrosion resistance, moderate strength
electrical connectors, hot metal handling
High Copper
C81400 to C82800
unique combination of high strength and thermal and electrical conductivity, high hardness, wear and fatigue resistance, corrosion resistance
electrical contacts, clamps, welding gear, bearings, molds for plastics
Red Brass
C83300 to C83810
high aqueous and atmospheric corrosion resistance, moderate strength and electrical conductivity
valves, pumps, plumbing and boat hardware, pipe fittings, terminal ends for electric cables
Semi-Red Brass
C84200 to C84800
moderate corrosion resistance and strength
low-pressure water valves, plumbing, hardware, pipe fittings, faucets
Yellow Brass
C85200 to C85800
pleasant yellow color, easily polished, lower corrosion resistance
decorative hardware, architectural trim, plumbing fixtures, bushings, fittings
Copper-Bismuth & SeBiLOY
C89320 to C89940
lubricity, good machinability without lead, meets potable water standards
bearings and bushings, plumbing fixtures, valves and fittings for potable water, food processing
Manganese Bronze
C86100 to C86800
high strength (as cast), good wear resistance, moderate corrosion resistance
gears, bolts, valve stems, marine fittings, propellers
Silicon Bronze & Silicon Brass
C87300 to C87800
moderate strength, high corrosion resistance, low melting point
bearings, gears, valve stems, intricate pump and valve components, boat propellers
Tin Bronze
C90200 to C91700
good corrosion resistance, ductility and wear resistance, reasonable strength, low friction coefficient vs. steel
bearings, piston rings, seal rings, valve fittings, gears, hydraulic and high-pressure steam parts, bells
Leaded and HighLeaded Tin Bronze
C92200 to C94500
improved machinability and pressure tightness relative to tin bronzes, improved lubricity
similar to tin bronzes plus sleeve bearings
Nickel-Tin Bronze
C94700 to C94900
moderate strength, good corrosion and wear resistance
bearings, gears, nozzles, wear guides, valve and pump components, machinery parts, motion translation devices
Aluminum Bronze
C95200 to C95900
high strength, good corrosion, erosion-corrosion and cavitation resistance, good galling resistance hooks and baskets
propellers, pump impellers, pump and valve parts, bearings, wear rings, marine hardware, pickling
Copper-Nickels
C96200 to C96950
excellent seawater corrosion resistance, bio-fouling resistance, stress corrosion cracking resistance in ammonia, high strength
marine equipment including pump components, impellers, valves, ship tailshaft sleeves, pipes, pipe fillings
Nickel Silvers
C97300 to 97800
good aqueous corrosion resistance, high castability, moderate strength, pleasant silver luster architectural trim, musical instrument valves
valves, fittings, hardware for food and beverage handling, seals and labyrinth rings in steam turbines,
Leaded Coppers
C98200 to C98840
corrosion resistance of copper with favorable lubricity and low friction, high conductivity
auto main and connecting rod bearings
good thermal conductivity, oxidation resistance and thermal fatigue resistance, high hot hardness
glassmaking molds, plate glass rolls, marine hardware
Special AlloysIncramet 800
2006 CASTING SOURCE DIRECTORY
ENGINEERED CASTING SOLUTIONS
37
This 6-in. brass frame was cast to hold a rheostat and gear mechanism that supplies power to a locomotive’s speed controller. By converting from a steel fabrication to a copper casting, the component needs no plating, and machining decreased substantially.
(0.2-6.5%) and may contain lead (0.5-7%). In red brass, lead is present to promote pressure tightness in service and to facilitate free machining during manufacturing. The red color is due to low zinc content. The highest volume red brass alloy (C83600) has been used commercially for hundreds of years and accounts for more tonnage than any other alloy. Semi-Red Brass (C84200 to C84800)— Semi-red brass has higher zinc content than the red brasses, which reduces corrosion resistance, lowers raw material costs and lightens the color (but has little effect on strength). Because of their outstanding aqueous corrosion resistance, red
brass and semi-red brass often are used in plumbing fittings, such as unions, valves and water meters. Yellow Brass (C85200 to C85800)—
The yellow brasses are lower in cost than the red brasses because their zinc content is higher (20-41%). In addition, they have good castability, with some alloys being permanent mold or diecast. Yellow brass has a pleasant yellow color that can be polished to a high luster. Copper-Bismuth and SeBiLOYS (C89320 to C89940)—The copper-bismuth and selenium-bismuth (SeBiLOY) alloys are low-lead brass alloys that are used in food process and potable water applications. The three SeBiLOY alloys
Table 2. Typical Properties of Commonly Used Copper-Base Casting Alloys (as published in “Casting Copper-Base Alloys” by AFS) Nominal Chemical Analysis (%) UNS Alloy Number Name
Cu
C81100 Copper
100
C82500 Beryllium copper
97
Sn
Pb
Zn
Fe Al
Tensile Properties Others
2Be, 1Co
YS (ksi)
Elon. (%)
Elon. 0.001 0.01 (psi in. set in. set x106)
Bhn Impact* Fatigue** Spec. Thermal Electrical (ft lb) strength gravity cond.% cond. % (ksi) of copper IACS
28
4
45
17
40
80
40
20
18
150
C83450 Leaded red brass
88
2.5
2
6.5
37
15
34
C83600
85
5
5
5
38
16.5
34
C83800
83
4
5
7
36
16
30
1 Ni
Compression Strength
UTS (ksi)
12
10
14
55
14
18
65
C-11
63
1-8
12
C84400 Leaded semired brass
81
3
7
9
34
14
27
10
C84800
76
2.5
6.5
15
38
14.9
37
15
C-45
16
58
C-12
100
100
8.3
30
20
13
8.8
11
8.8
18
15
8.7
18
15.2
8.7
18
16.6
8.8
18
16.5
55 13
8.9
11
20
C85200 Leaded yellow brass
72
1
3
24
38
13
40
13
9
46
8.5
21
18.6
C85400
67
1
3
29
34
12
35
13
9
55
8.5
23
19.6
C85700
61
1
1
37
52
18
50
22
21.8
C86200 Mn bronze
64
26
3
4
3 Mn
94
48
22
15
50
C86300
62
25
3
6
4 Mn
120
69
16
14
71
C86400
58
38
1
1
0.5 Mn
69
26
23
13
23
C86500
58
39
1
1
0.5 Mn
72
30
37
15
24
C87200 Silicon bronze
92
4
4 Si
60
25
40
17
19
C87500 Silicon brass
82
14
4 Si
67
32
20
15
27
1
0.3
77 97 35 43
8.4 180
I-12
235
C-14
88
I-30
130
C-30
87
I-30
120
C-32
22
80
I-10
13
70
C-14
C90300 Tin bronze
88
10
2
48
21
36
15
C90500
88
8
4
47
20
38
15
C92200 Leaded tin bronze
88
6
1.5
4.5
42
18
43
13
15
64
C-19
C92300
87
8
1
4
44
18
35
14
10
70
I-14
C92600
87
13
70
I-9
13
10
1
2
44
20
32
14
C93200 High-leaded tin 83
7
7
3
40
18
35
15
C93500 Bronze
85
5
9
1
35
17
30
12
C93700
80
10
10
39
18
30
1218 22
C93800
78
7
15
34
17
30
10
C94300
70
5
25
27
14
20
11
18
67 13
60 65
25 21
11
16 I-8
C-11 13
9.0
15
61
I-5
10
13
55
I-5
7.9
9
7.4
7.7
9
7.7
8.2
22
19.3
8.3
22
21.5
8.3
7
6.1
8.3
7
6.5
8.7
19
10.9
8.7
19
12.4
8.7
18
13.8
8.8
18
12.3
8.8
13
10.8
8.9
15
12.4
8.9
17
14.9
12
10.0
9.2
13
11.6
9.4
16
9.0
C95200 Al bronze
88
3
9
82
27
40
17
28
125
I-40
23
7.5
13
12.2
C95300
89
1
10
77
28
21
16
20
140
I-30
22
7.5
16
15.1
C95400
86
4
10
90
35
15
18
160
I-15
30
7.5
15
13.0
C95500
81
4
11
4 Ni
102
43
11
19
195
C-9
32
7.5
11
8.9
C95800
81.5
4
9
4.5Ni, 1Mn
96
38
25
19
48
160
C-15
30Ni, 1Nb
70
40
25
21
140
C-78 18
C96400 Cupronickel 30% 67
1
35
31
7.5
11
8.9
8
8.9
8.9
C97300 Leaded nickel
57
2
9
20
12 Ni
39
17
35
16
60
8.9
7
6.5
C97400 Silver
60
3
5
16
16 Ni
40
17
30
16
65
8.9
7
5.4
C97600
64
4
4
8
20 Ni
48
26
22
19
C97800
66
5
2
2
25 Ni
58
33
15
19
*I-Izod C-Charpy
**endurance limit—100 million cycles
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ENGINEERED CASTING SOLUTIONS
24
31
80 130
C-11
15
8.9
6
5.0
8.9
6
4.6
2006 CASTING SOURCE DIRECTORY
were developed to minimize lead leaching into potable water and to replicate the high machinability and pressure tightness of leaded brass. This is realized by substituting selenium and bismuth for lead. SeBiLoy I and II are red brasses and SeBiLOY III is a yellow brass.
chloride and dilute acids. Applications are varied and include propellers and valves, pickling hooks, pickling baskets and wear rings. The aluminum bronze alloys that contain nickel are desirable for fluid-moving applications, such as pump impellers, because of superior erosion, corrosion and cavitation resistance.
Bronzes Bronze is an imprecise term. It originally referred to alloys in which tin was the major alloying element. Under the UNS system, the term bronze (C86100 to 87800, C90200 to C95900) applies to a broad class of alloys in which the principal alloying element is neither zinc nor nickel. Nevertheless, bronze is the common name for a number of alloys that contain little, if any, tin. Manganese-Bronze (C86100 to C86800)—Manganese-bronze, which contains zinc (22-42%) as the major alloying element, is among the strongest cast copper alloys and is used for gears, bolts and valve stems. Where economically feasible, aluminum-bronze replaces manganese-bronze because it offers high strength in combination with better corrosion resistance. Silicon-Bronze and Silicon-Brass (C87300 to C87800)—Silicon-bronze and silicon-brass are alloys of zinc and silicon that have low melting points and high fluidity, which favor permanent mold and diecasting. Because of its low lead content, silicon-bronze often is a replacement for leaded plumbing brasses, but its limited machinability inhibits use in high-volume potable water systems. It is currently being used as a substitute for semi-red brass in immersed pumps. Tin-Bronze (C90200 to C91700)—Tinbronze is an alloy of copper and tin with good aqueous corrosion-resistance. Additional attributes include high strength, good wear resistance and a low friction coefficient compared to steel. This accounts for its use in bearings, piston rings and gear parts. Leaded Tin-Bronze (C92200 to C92900)—These alloys are a tin-bronze containing 0.3-6% lead. Leaded tin-bronze offers the additional advantage of free cutting. High-Leaded Tin Bronze (C93100 to C94500)—This is a tin-bronze containing 2-34% lead. High-leaded tinbronze is used in sleeve bearings and bushings because the additional
Other Alloys
Nickel-aluminum bronze (shown cast as an impeller) often is specified for fluid handling equipment used in aggressive environments, such as seawater.
lead provides improved lubricity. Nickel-Tin-Bronze (C94700 to C94900)—This is a tin-bronze containing 4-6% nickel. Nickel-tin-bronze is a versatile alloy that has the good wear resistance and corrosion resistance found in tinbronzes with improved strength. Nickeltin-bronze is used in many applications including bearings, gears, wear guides, and pump and valve components, and in motion and translation devices, such as shift forks and circuit breaker parts. Aluminum-Bronze (C95200 to C95900)—Aluminum-bronze has a complex metallurgical structure that imparts both strength and oxidization resistance due to the formation of alumina-rich protective films. These alloys are wearresistant and exhibit good casting and welding characteristics. Their corrosion resistance is superior in seawater,
This adapter used on a control head of a power pallet truck is made from yellow brass. Converted from a fabrication of 13 components, this casting helped reduce cost savings by 25% and achieve required strength properties to fight wear and tear.
2006 CASTING SOURCE DIRECTORY
Copper-Nickel (C96200 to 96950)— These alloys are simple solid solutions of nickel in copper without lead. The copper-nickel alloys have excellent corrosion resistance in seawater, high strength and ease of manufacturing. Their various applications include pumps, valves, ship tail shaft sleeves and other marine applications. Nickel-Silver (C97300 to C97800)— The presence of nickel accounts for these alloys’ silver luster. These alloys, which do not contain silver, offer good corrosion resistance, ease of castability and good machinability. Despite their high degree of alloying, these alloys are simple solid solutions. Major uses include hardware for food processing, seals, architectural trim and musical instrument valves. Leaded-Coppers (C98200 to C98840)— These are essentially pure copper or high-copper alloys containing lead. The leaded-coppers offer the moderate corrosion resistance and high conductivity of the copper alloys, in addition to the lubricity and low friction characteristics of high-leaded bronzes. Special Alloys (C99300 to C99750)— These are alloys with unique characteristics, such as Incrament 800 (C99300), which has high oxidation resistance due to aluminum, good thermal fatigue resistance and high hot hardness. This alloy was developed for glass processing including glassmaking molds and plate glass rolls.
Design for Manufacturing The choice of alloy and casting method (sand, permanent mold, die or investment casting) determines the mechanical and physical properties, section size, wall thickness and surface finish that can be achieved. Each alloy and casting process combination results in a different set of properties. If metalcasting facility and design engineers can work together on the “raw” or ideal component, all options will be considered early in the design process, resulting in a design and component that take advantage of the versatility that ECS copper alloys offer. ENGINEERED CASTING SOLUTIONS
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