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ZL12

Aluminium Zinc Foundry Alloy ZL8

This alloy conforms to EN 1774 1997

Chemical Composition

  %   %   %
 Aluminium  10.8-11.5  Copper  0.5-1.2  Magnesium  0.02-0.03
 Zinc  Remainder        
 Impurities          
 Iron  0.05 max  Lead  0.005  Cadmium  0.005 max
 Tin  0.002 max  Silicon  0.05 max    

 

Mechanical Properties of Aluminium Zinc ZL8

 

Sand Casting

Gravity Die Casting

Tensile Strength (N/mm2)

276-310

345-380

Elongation (%)

3-4

4-7

Brinell Hardness

105-125

105-125

Impact Strength at 20°c (J)

5.4-10.8

17.6

Strength at elevated temperatures

Due to its low melting temperature this alloy is not recommended for components whose service exceeds 100°C. In addition reference should be made to ZL8 mechanical properties at elevated temperatures and the alloy's creep properties for continually stressed components.

Physical Properties of Aluminium Zinc ZL8

 

 

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 aluminium zinc 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 a zinc diecasting requiring substantial or difficult machining.

Corrosion Resistance

A diecasting in this alloy possess 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 diecasting 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 a short freezing range and excellent fluidity during diecasting, this alloy is ideal for thin wall components. These cover a whole range of applications from functional components, (because of its good tensile strength, hardness and pressure tightness), to decorative thin wall components (because of its ease of electro-plating and painting). THe mechanical properties shown above are for pressure diecast components but this alloy can also be gravity diecast.

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