Zinc Alloys
Zinc-based alloys are the easiest for die casting. Ductility is high and impact strength is excellent, making these alloys suitable for a wide range of products. Zinc die casting provides thin walls and excellent surface smoothness making preparation for plating and painting relatively easy.
It is essential that only high purity (99.99 + 0/0) zinc metal be used in the formulation of alloys. Low limits on lead, tin and cadmium ensure the long-term integrity of the alloy’s strength and dimensional stability.
Table 2:
COMPOSITION AND PROPERTIES OF ZINC DIE CASTING ALLOYS
|
DESIGNATIONS COMPOSITION (in percent max. unless shown as range for die castings) … for ingots |
ZAMAK 2 |
ZAMAK 3 |
ZAMAK 5 |
ZAMAK 7 |
ZA-8 |
ZA-12 |
ZA-27 |
|
Aluminum |
3.7-4.3 |
3.5-4.3 |
3.5-4.3 |
3.5-4.3 |
8.0-8.8 |
10.5-11.5 |
25.0-28.0 |
|
Copper |
2.6-3.3 |
0.25 |
0.75-1.25 |
0.25 |
0.8-1.3 |
0.5-1.25 |
2.0-2.5 |
|
Magnesium |
0.02-0.06 |
0.02-0.05 |
0.03-0.08 |
0.005-0.020 |
0.015-0.030 |
0.015-030 |
.010-.020 |
|
Iron |
0.05 |
0.1 |
0.1 |
0.075 |
0.1 |
0.075 |
0.1 |
|
Lead |
0.005 |
0.005 |
0.005 |
0.003 |
0.004 |
0.004 |
0.004 |
|
Cadmium |
0.004 |
0.004 |
0.004 |
0.002 |
0.003 |
0.003 |
0.003 |
|
Tin |
0.002 |
0.003 |
0.003 |
0.001 |
0.002 |
0.002 |
0.002 |
|
Nickel |
0 |
0 |
0 |
0.005-0.020 |
0 |
0 |
0 |
|
Zinc |
Bal. |
Bal. |
Bal. |
Bal. |
Bal. |
Bal. |
Bal. |
| PROPERTIES (see notes) | |||||||
|
Ultimate tensile strength (ksi) |
52 |
40 |
48 |
41 |
54 |
58.5 |
61 |
|
Tensile yield strength (ksi) |
41 |
32 |
39 |
32 |
42 |
46 |
53 |
|
Elongation (% in 2″ (55 mm)) |
7 |
10 |
7 |
13 |
10-Jun |
7-Apr |
3-Jan |
|
Hardness (HB) |
100 |
82 |
91 |
80 |
95-110 |
95-115 |
105-125 |
|
Shear strength (ksi) |
46 |
31 |
38 |
0 |
35 |
37 |
42 |
|
Charpy impact strength (ft. lb.óunnotched) |
35 |
43 |
48 |
43 |
31 |
21 |
3 |
|
Fatigue strength (ksi) (limit @ 500 million cycles) |
8.5 |
6.9 |
8.2 |
0 |
7.5 |
15 |
25 |
|
Density (lb./in.3) |
0.24 |
0.24 |
0.24 |
0.247 |
0.227 |
0.218 |
0.181 |
|
Melting range (oF) |
715-734 |
718-728 |
717-727 |
718-728 |
707-759 |
710-810 |
708-903 |
|
Specific heat (Btu/lb.oF) |
0.1 |
0.1 |
0.1 |
0.1 |
0.104 |
0.107 |
0.125 |
|
Coefficient of thermal expansion (in./in./oF) |
15.4 |
15.2 |
15.2 |
15.2 |
12.9 |
13.4 |
14.4 |
|
Thermal conductivity (Btu/fthr.oF) |
60.5 |
65.3 |
62.9 |
65.3 |
66.3 |
67.1 |
72.5 |
|
Electrical conductivity (% IACS) |
25.0 |
27 |
26 |
27 |
27.7 |
28.3 |
29.7 |
|
Modulus of elasticity (106 psi) |
0 |
0 |
0 |
0 |
10.2 |
10.3 |
10.3 |
|
Die shrinkage (in./in.) |
0.007 |
0.007 |
0.007 |
0.007 |
0.007 |
0.0075 |
0.008 |
