The effect of Cu, Zn, and Bi additions on the high-temperature deformation behavior of A1-3.0Mg alloys
Fine-grained aluminum AA5083 has been used in General Motors (GM) Corporation's proprietary manufacturing process, quick-plastic forming, a derivative of superplastic forming. The high magnesium content in AA5083 provides solid-solution strengthening and is necessary in obtaining required postformed strength. However, the high magnesium content makes processing difficult due to the large forces and high power required during rolling. This report studies an aluminum with a lower magnesium content, 3.0wt.% Mg, with copper and zinc additions for age-hardening and bismuth additions for tribological reasons. The six alloys analyzed for this investigation, a reference alloy (Al-3.30Mg-0.72Mn), a copper-containing alloy, a zinc-containing alloy, a copperand zinc-containing alloy and two bismuth-containing alloys, were cast and processed into sheet material. Differential scanning calorimetry (DSC) and electrical conductivity experiments were conducted to determine optimum heat treatments prior to rolling. Particle-size distribution analysis was performed at each processing step to track particle-size distribution evolution during processing. The mechanical behavior of these materials was characterized using elongation-to-failure (EF) tests and strain-rate-change (SRC) test coupled with grain size measurements. Results from this analysis are encouraging for more detailed studies.