Zinc Alloy 2 is sometimes referred to as Kirksite and is the only zinc alloy used for gravity casting, mainly for metal forming dies or plastic injection tools. For diecasting, this alloy offers the highest strength and hardness of the family. However, due to the high copper content (3%), changes to the material properties occur with long-term ageing. These changes include slight dimensional growth (0.0014 mm/mm [in/in] after 20 years), lower elongation and reduced impact performance.
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Zinc Alloy 2 is sometimes referred to as Kirksite and is the only zinc alloy used for gravity casting, mainly for metal forming dies or plastic injection tools. For diecasting, this alloy offers the highest strength and hardness of the family. However, due to the high copper content (3%), changes to the material properties occur with long-term ageing. These changes include slight dimensional growth (0.0014 mm/mm [in/in] after 20 years), lower elongation and reduced impact performance.

Although this alloy exhibits excellent casting characteristics, it has seen limited use by diecasters. It does however possess some interesting characteristics that may be of assistance to designers. Its creep performance is rated higher than the other zinc alloys and it maintains higher strength and hardness levels after long-term ageing.

The behaviour of zinc alloys under stress is non-linear and time-temperature dependent on strain-rate, i.e. the ratio of stress to strain is not constant, even at low stresses, and varies with time resulting in continuous plastic flow under constant applied load. Designers of structural components should be aware of the creep limitations of zinc alloys, which do not have a single value for elastic modulus or yield strength. Yield strength (allowable stress) under sustained loading is dependent on the allowable design strain (% elongation) over the required service life. Working values for the elastic modulus and yield strength are important for design purposes.

Standard engineering formulae used for calculating cross-sections of elastic materials must therefore be used with some caution. The value given for Young's modulus in the table below should only be used as a first estimate.

This alloy exhibits excellent damping capacity and vibration attenuation in comparison with aluminium diecasting alloys.