Application of Combined W-Temper and Cold Forming Technology to High-Strength Aluminum Alloy Automotive Parts

In this study, a room temperature forming process for high-strength aluminum alloys was investigated. To overcome the low formability of the peak-aged 7075 aluminum alloy (7075-T6) at room temperature, the sheet metal was subjected to solution heat treatment followed by rapid quenching. Mechanical tests, including uniaxial and balanced biaxial tension tests, were performed, and the Nakajima test was conducted to evaluate the formability of the sheet metal. On the basis of the plastic deformation behavior, finite element models including the plastic yielding and strain hardening laws were constructed. The proposed forming process incorporating the W-temper heat treatment was successfully applied to a realistic automotive part, which could not be manufactured by conventional room temperature forming without prior heat treatment. The numerical accuracies among various plasticity models were evaluated from a comparison of the thickness profiles. In addition, the paint-bake process was applied to the automotive component to evaluate the strength recovery.