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