Pressure Die Casting Zinc Alloys
|Publication Date:||1 June 2016|
This material specification applies to zinc alloys for use in high pressure die cast automotive applications and other allied industries. Zinc die casting alloys are specified by chemical composition. The alloys indicated represent common materials for identical product requirements across GM worldwide.
Material Description. Zinc base casting alloys use aluminum and copper as the primary alloying elements with small amounts of magnesium added to minimize susceptibility to intergranular corrosion. The alloying elements determine the primary phases that give the material its mechanical and physical properties. The primary phases that are formed (see 3.3) results in three distinct alloy groups which are described in Table A1 in Appendix A. High pressure zinc die castings are also characterized by excellent castability and wear properties. Zinc alloy castings are to be made from ingots that meet the requirements of the global specification for Zinc Alloy Ingots for High Pressure Die Casting, GMW3344.
Symbols. Not applicable.
Applicability. Because of their higher density, zinc alloy castings are less widely used in automotive applications than they were historically. They still do have a place, however, where intricate castability and high strength coincide. Typical applications and alloy selection criteria for major subsystems are provided in Table B1 in Appendix B. Zinc alloys are capable of being die cast with complex details, close tolerances and thin walls, thus making them attractive for many automotive applications. Both Zamak and ZA alloys are used for decorative and non-structural applications and, in some cases, the ZA alloys are also used for structural components. ACuZinc is a patented family of zinc casting alloys developed by General Motors. The ACuZinc alloys have higher strength and hardness and better creep and wear properties than the Zamak and ZA alloys. This makes them suitable for a variety of applications where the Zamak and ZA alloys are unsuitable.
Remarks. Table A1 in Appendix A contains a cross reference between GMW3341 alloy grades and their respective commercial alloy designations, American and European standards and is presented for reference only. GMW3341 requirements may differ from those in other specifications. Cross referenced alloys are not interchangeable with their GMW3341 counterpart.