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ACuZinc 5 and ACuZinc 10 belong to a family of new, high-performance ternary zinc-copper-aluminum alloys which are suitable for manufacturing net shape die castings. The GM-patented ACuZinc die castings have superior wear and creep properties compared to similarly manufactured Zamak 3 and ZA alloy commercial die castings. These improved alloys offer opportunities for designers interested in achieving significant performance advantages, and the potential for extending the use of net shape zinc die castings to structural applications at elevated temperatures where creep, wear and/or strength had previously been an issue.

ACuZinc™ 5, a GM-patented, high-performance ternary zinc-copper-aluminum alloy which is suitable for manufacturing net shape die castings, plays a vital role in the success of new automotive parts and systems. The new parts were designed to meet the auto industry's higher load and safety specifications. The superior mechanical properties of ACuZinc™ make it suitable for structural applications where commercial zinc die casting alloys have been found to be inadequate. From a business viewpoint, ACuZinc™ can help in penetrating new markets by competing for cast iron, powder metal and brass applications. ACuZinc is a registered GM trademark.

High strength steels, such as the dual phase steels and high strength, low alloy steels, offer potential for wheel weight reduction but have been used sparingly, in part, because of a special problem that is unique to wheel rim fabrication. Compared to plain carbon steel, these steels have a higher tendency for weld related neck formation during rim fabrication and this contributes to a higher production scrap rate. This paper investigates mechanical property and microstructural changes produced in the flash butt welded, heat affected zone of one commercially available dual phase steel. Heating conditions most likely to increase the tendency for localized necking are identified. Micro-structural phenomena that might be responsible for the problem are discussed and plausible solutions are suggested.

Automotive component weight can often be reduced by replacing plain carbon steel with thinner high strength steel. However, the poor formability of the latter steels has, in part, restricted their use. GM 980X has far better formability than conventional SAE 980X, high-strength low-alloy (HSLA) steels and can develop the strength of the SAE 980X steels in the formed part. This paper discusses the performance of GM 980X steel in various wheel rim and disc forming trials and in component fatigue tests conducted with the objective of meeting the established performance requirements of plain carbon steel wheels with lighter weight HSLA wheels. Results suggest that GM 980X can be a viable substitute for plain carbon steel in wheels with weight savings as high as 25%.

The joining of metals by welding results in unavoidable heating of adjacent material causing the formation of a weld heat affected zone (HAZ). Deformation of the weld zone as during automotive wheel rim fabrication is reported to develop a non-uniform strain distribution in the weld HAZ of high strength steels. This can lead to the formation of a localized neck in the HAZ and hence, a higher production scrap rate in these steels compared to plain carbon steel. This report examines the mechanical property changes that occur in the weld HAZ of three commercial high strength steels and a plain carbon steel. These mechanical property changes are explained in terms of the phase transformations that occur on heating the steels during welding, and the explanations provide insight into potential solutions for reducing the tendency for post-weld, deformation-induced necking during automotive rim fabrication.

The mechanical properties of GM 980X, a unique high strength low alloy steel with formability better than that of SAE 950X steels and the strength of SAE 980X steel in the formed component, are reviewed and the microstructure which produces these properties is described. A brief comparison is made between GM 980X and other steels with similar microstructures. The superior formability and weight saving potential of GM 980X has been demonstrated in various component trials. Some potential automotive applications are listed and a few forming trials and qualification tests to validate component strength are described.

Substituting high strength low alloy (HSLA) steels for plain carbon steel in strength limited automotive components could reduce weight and conserve steel. However, the poor formability of these steels has, in part, restricted their use in automotive applications. This paper discusses a simple treatment which transforms some commercially available 980X steels into a product with the following desirable mechanical properties: (a) Yield strength of 950X steels in the as-treated condition but equal to that of 980X steels after 2-3% deformation, (b) Tensile strength of 980X steels, (c) Superior formability, equal to or better than that of 950X steel in hot rolled gages, i.e., thicker than ∼2 mm (0.075″), and approaching that of plain carbon steel in cold rolled gages. This material, named GM 980X, could significantly increase the use of 980X steels in automotive applications.