Aluminium Zinc Foundry Alloy ZA12
Mechanical Properties of Aluminium Zinc ZA12
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Tensile Strength (N/mm2) |
276-310 |
345-380 |
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Elongation (%) |
3-4 |
4-7 |
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Brinell Hardness |
105-125 |
105-125 |
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Impact Strength at 20°c (J) |
5.4-10.8 |
17.6 |
Strength at elevated temperatures
Due to its low melting temperature ZA12 is not recommended for components whose service temperature exceeds 100°C. Strength will decrease with an increase of temperature from 20°C. In addition reference should be made to ZA12 mechanical properties at elevated temperatures and to the alloy's creep properties for continually stressed components.
Physical Properties Coefficient of Thermal Expansion (per °C @ 20-100°C) 0.0000028 Thermal conductivity (cal/cm2/cm/°C @ 25°C) 0.21 Electrical conductivity (% copper standard @ 20°C) 25 Density (g/cm3) 6.03 Freezing range (°C) approx. 430-380
Machinability
This alloy has excellent machining characteristics, which means fast, efficient machining and long tool life. Therefore, unlike its competing materials, it is an ideal alloy for components requiring substantial or difficult machining.
Corrosion Resistance
Aluminium zinc die casting in this alloy produces good corrosion resistance but weathering will turn the surface grey in colour, therefore, for decorative purposes it should be lacquered, plated or painted, and for more corrosive environments chromating or zinc anodising should be considered.
Anodising
A process for anodising zinc and zinc alloy die casting has been developed and is reported to give excellent resistance to salt water and good resistance to abrasion. The finish is available only in matt light green, grey and brownish tints. The treatment is covered by U.S. Government specification MIL-A-81801.
Application and General Notes
With its excellent mechanical and physical properties aluminium zinc alloy ZA12 has a whole range of potential applications from stressed functional components (because of its high tensile strength, hardness, bearing properties and pressure tightness), to purely decorative thin wall components because of its ease of electro-plating and painting.
A significant advantage of this zinc alloy is that it is non-sparking. This enables its use in hazardous environments such as underground mining and petroleum plants.