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This paper describes the tensile creep and microstructure of Mg-Al-Ca-based ACX magnesium alloys being developed for powertrain applications. Important creep parameters, i.e., secondary creep rate and creep strength, for the new alloys are reported. Tensile creep properties of the newly developed ACX alloys are significantly better than those of AE42 alloy, which is the benchmark creep-resistant magnesium die casting alloy. Creep mechanisms for different temperature/stress regimes are proposed. A new intermetallic phase, (Mg,Al)2Ca, was identified in the microstructure of the ACX alloys, and is proposed to be responsible for the improved creep resistance of the alloys.

In this paper, the mechanical properties, structural performance and mass saving potential of wrought magnesium alloys are compared to several major automotive materials: mild steel, advanced high-strength steel, cast and wrought aluminum, cast magnesium, plastics and fiber-reinforced composites. Manufacturing processes including welding and joining of magnesium extrusions and sheet products are critically reviewed. The current and potential applications of wrought magnesium alloys in automotive interior, body and chassis areas are discussed. Technical challenges and research opportunities for these applications are identified.

Aluminum tube hydroforming offers further mass savings and performance improvement compared to solid stampings and castings. This paper reports the formability of 6063-T4 extruded tubes and 5754 seam-welded tubes. Tensile and fatigue properties of the hydroformed sections are investigated. The results also show that despite its lower yield strength (but higher ultimate tensile strength and ductility), the hydroformed 5754 alloy has higher fatigue resistance than the 6063-T7 material.