Copper Alloys
Copper-based alloys are generally known as brass or bronze. They provide the highest mechanical properties of any of the more common die casting alloys. Brasses have high strength and toughness, good wear resistance and excellent corrosion resistance. Dimensional stability is excellent. Of the various brass die casting alloys available, alloy Z30A is used for the majority of die casting applications.
Table 4:
COMPOSITION AND PROPERTIES OF COPPER ALLOY FOR DIE CASTING
|
ASTM DESIGNATION (Commercial) |
Z30A (858) |
ZS331A (879) |
ZS144A (878) |
|
Composition (1) |
|||
|
Copper, per cent |
57.0 min. |
63.0 to 67.0 |
80 to 83 |
|
Silicon, per cent |
0.25 max. |
0.75 to 1.25 |
3.75 to 4.25 |
|
Lead, max., per cent |
1.50 |
0.25 |
0.15 |
|
Tin, max., per cent |
1.50 |
0.255 |
0.25 |
|
Manganese, max., per cent |
0.25 |
0.15 |
0.15 |
|
Aluminum, max., per cent |
0.25 |
0.15 |
0.15 |
|
Iron, max., per cent |
0.50 |
0.15 |
0.15 |
|
Magnesium, max., per cent |
ó |
ó |
0.01 |
|
Other elements, max., per cent |
0.50 |
0.50 |
0.25 |
|
Zinc, per cent |
30.0 min. |
Remainder |
Remainder |
|
PROPERTIES AND CONSTANTS (2) |
|||
|
Tensile Strength, (ksi) |
55 |
70 |
85 |
|
Tensile Yield Strength 0.2% offset (ksi) |
30 |
35 |
50 |
|
Elongation, (% in 2 in.) |
15 |
25 |
25 |
|
Impact Strength, Charpy. (ft. lb.) |
40 |
50 |
70 |
|
Hardness, (HRB) |
55-60 |
68-72 |
85-90 |
|
Modulus of Elasticity (x 106 psi) |
15 |
15 |
20 |