Table 1: Zinc Alloying elements and their properties
| Element | Effect |
| Aluminum |
|
| Copper |
|
| Nickel |
|
| Magnesium |
|
Wrought Zinc Alloys
Wrought zinc has chemical characteristics particularly adapted to certain uses, such as dry batteries and photoengraver`s plate, and offers combinations of desirable physical and mechanical properties at relatively low cost. In common with many other metals and alloys, wrought zinc creeps under constant loads that are substantially less than its ultimate strength. The ordinary grades of wrought zinc can be soldered easily by conventional methods.
Zinc gravity casting alloys can be used for general industrial applications where strength, hardness, wear resistance or good pressure tightness is required. Zinc alloys often are employed to replace cast iron because of their similar properties and higher machinability ratings. The good bearing and wear characteristics of zinc alloys permit them to be used for bearing bushings and flanges. Other applications in which zinc alloys have been successfully substituted for cast iron or copper alloys include fuel-handling components, pulleys, electrical fittings and hardware components.
Zinc Casting Alloys
pure Zinc is never used in casting due to it's low strength. It is commonly used as an alloy that is primarily Zinc with alloying elements of Aluminum, Magnesium and Copper as well as other trace impurities. Today, all Zinc alloys supplied by reputable producers are made from primary of virgin Zinc which conforms to the SHG (super high grade) or Zn 1 brand which is quoted in commodity markets worldwide. Zinc of this standard is 99.995% pure and has to conform to international quality specifications.
ZAMAC Zinc Alloys
ASTM B86 casting alloys (as cast)
Table 2: ZAMAC alloy properties
| number | alloy properties |
| ZAMAK-8 | 8% Aluminum and Zinc
|
| ZAMAK 3 | 12% Aluminum and Zinc
|
| ZAMAK | 27% Aluminum and Zinc
|
The current Zinc alloy chemistry specifications originate from around 1935, from research by The New Jersey Zinc Corporation, who introduced the generic name Zamak to zinc alloys.
ZAMAK 2 (#2): This is the strongest and hardest ZAMAK alloy. Generally die cast, it is occasionally employed for gravity casting. ZAMAK 2 is not widely used.
ZAMAK 3 (#3): This is the most used general purpose zinc die casting alloy, providing an excellent combination of strength, ductility and impact strength. It also provides excellent plating and finishing characteristics. This alloy is the designer's first choice for die casting applications.
ZAMAK 5 (#5): ZAMAK 5 should be considered when moderately greater hardness, strength and creep resistance over ZAMAK 3 is required.
ZAMAK 7 (#7): this is a high purity for of ZAMAK 3 with similar mechanical properties. However, ZAMAK 7 has higher ductility (for forming bending operations) and the highest casting fluidity of the ZAMAK family.
Table 3: ZAMAK series alloy composition
| Designation | ZP2 | ZP3 | ZP5 | ZP7 | |
| UNS Alloy Number | Z35541 | Z33520 | Z35531 | Z33523 | |
| ASTM Number | AC43A | AG40A | AC41A | AG40B | |
| Alloy Symbol | ZnAl4Cu3 | ZnAl4 | ZnAl4Cu1 | ||
| Aluminum % | Max. | 4.3 3.5 |
4.3 3.5 |
4.3 3.5 |
4.3 3.5 |
| Min. | |||||
| Copper % | Max. | 3.0 2.5 |
0.25 N/A |
1.25 0.75 |
0.25 N/A |
| Min. | Magnesium % | Max. | 0.050 0.020 |
0.050 0.020 |
0.080 0.030 |
0.020 0.005 |
| Min. | Nickel % | Max. | N/A | N/A | N/A | 0.005 0.020 |
| Min. | |||||
| Iron (Fe) | Max (%) | 0.10 | 0.10 | 0.10 | 0.075 |
| Lead (Pb) | Max (%) | 0.005 | 0.005 | 0.005 | 0.003 |
| Cadmium (Cd) | Max (%) | 0.004 | 0.004 | 0.004 | 0.002 |
| Tin (Sn) | Max (%) | 0.003 | 0.003 | 0.003 | 0.001 |
Zinc-Aluminum alloys (ZA)
ASTM B791 alloys
Table 4: ZA alloy properties
| number | alloy properties |
| ZA-8 | 8% Aluminum and Zinc
|
| ZA-12 | 12% Aluminum and Zinc
|
| ZA-27 | 27% Aluminum and Zinc
|
ZA-8: This should be the first choice when considering die casting the ZA family, due to its cost effective hot chamber castability. ZA-8 provides improved performance characteristics over the ZAMAK alloys. Plating and finishing characteristics are similar. ZA-8 can also be sand or permanent mold cast.
ZA-12: This is the preferred alloy for permanent mold applications, although it can also be cal-chamber die cast with excellent results. It combines low temperature melting efficiency and thin wall capabilities with premium mechanical properties. ZA-12 should be used when switching from cast iron or permanent molded aluminum. ZA-21 can usually be poured directly into molds designed for aluminum and brass.
ZA-27: Components requiring optimum strength, hardness and light weight should be specified using ZA-27. With over double the yield strength of die cast A380 aluminum and 25% lighter than ZAMAK 3, this is definitely the high performance member of the group. ZA-27 also offers excellent bearing properties, comparable to those of aluminum-bronze.
Zinc-Aluminum alloys are generally die cast to form parts with intricate detail. These alloys contain higher aluminum content than standard zinc alloys. They provide high strength, plus high hardness and good bearing properties. Ability to cast thin walled parts and die life are similar to traditional zinc alloys. ZA-8 is recommended for hot chamber die casting, which ZA-12 and ZA-27 must be cast by the cold chamber die casting process. All ZA alloys offer similar creep properties and are superior to standard zinc alloys.
Although the ZA alloys were first introduced for gravity casting (sand and permanent mold), they have expanded into pressure die castings as well as the new, precision graphite-mold process. Important: Alloys ZA-12 and ZA-27 must be cold-chamber die cast; alloy ZA-8 is hot-chamber castable.
- High strength and hardness
- Excellent electrical conductivity
- High thermal conductivity
- Lowest cost raw material
- High dimensional accuracy and stability
- Excellent thin wall capability
- Ability to cold form, which eases joining
- High quality finishing characteristics
- Outstanding corrosion resistance
- Full recyclability
Table 5: ZA series alloying elements
| Designation | ZA8 | ZA12 | ZA27 | GM? | |
| UNS Alloy Number | Z35636 | Z35631 | Z35841 | Z?? | |
| ASTM Number | AC43A | AG40A | AC41A | ?? | |
| Alloy Symbol | |||||
| Aluminum % | Max. | 8.8 8.0 |
11.5 10.5 |
28.0 25.0 |
? ? |
| Min. | |||||
| Copper % | Max. | 1.30 0.80 |
1.20 0.50 |
2.50 2.00 |
? ? |
| Min. | Magnesium % | Max. | 0.030 0.015 |
0.030 0.015 |
0.020 0.010 |
? ? |
| Min. | |||||
| Iron (Fe) | Max (%) | 0.075 | 0.075 | 0.075 | ? |
| Lead (Pb) | Max (%) | 0.006 | 0.006 | 0.006 | ? |
| Cadmium (Cd) | Max (%) | 0.006 | 0.006 | 0.006 | ? |
| Tin (Sn) | Max (%) | 0.003 | 0.003 | 0.006 | ? |
GM proprietary alloy
The third alloy group consists of a single alloy, ACuZinc, which has copper as the primary alloying element. This alloy is patented by General Motors. ACuZinc has superior mechanical properties as compared to the other zinc alloys. It has greater hardness (118 Brinell), tensile strength (59 ksi) and even a higher modulus (14.5x106 psi). But its greatest superiority is in its creep resistance (710 hr. to fracture at 3,600 psi and 300F). It is nearly seven times as creep resistant as the ZA-8 alloy.
Physical properties of Zinc alloys
Table 6: Zinc physical properties
| #3 | #5 | #7 | #2 | ZA-8 | ZA-12 | ZA-27 | |
| Ultimate Tensile Strength: psi x 103 (MPa) | 41 (283) | 48 (328) | 41 (283) | 52 (359) | 54 (374) | 58 (400) | 61 (421) |
| Yield Strength - 0.2% Offset: psi x 103 (MPa) | 32 (221) | 39 (269) | 32 (221) | 41 (283) | 42 (290) | 46 (317) | 55 (379) |
| Elongation: % in 2" | 10 | 7 | 13 | 7 | 6-10 | 4-7 | 1-3 |
| Shear Strength: psi x 103 (MPa) | 31 (214) | 38 (262) | 31 (214) | 46 (317) | 40 (275) | 43 (296) | 47 (325) |
| Hardness: Brinell | 82 | 91 | 80 | 100 | 95-110 | 95-115 | 105-125 |
| Poisson's Ratio | 0.27 | 0.27 | 0.27 | 0.27 | 0.29 | 0.30 | 0.32 |