Conditions for Retrogression Forming Aluminum AA7075-T6 Sheet

Combining the retrogression heat treatment with simultaneous warm forming provides an opportunity to significantly increase the formability of high-strength aluminum alloys while subsequently regaining peak-aged strength through a single reaging heat treatment. This new technological approach is termed retrogression forming. Forming conditions suitable to the retrogression forming of an AA7075-T6 sheet material are examined through elevated-temperature tensile tests. Temperatures from 180 to 220 °C are investigated. Strain rate sensitivity and reduction in area increase with increasing temperature. Elongation to rupture increases with decreasing strain rate. An elongation to rupture of 35% was measured at 200 °C for a true strain rate of 3.2 × 10−3 s−1. While higher temperatures and slower forming rates encourage the behaviors associated with good formability, these must be balanced with the ability to reage to high strength after forming. Recommendations for designing and implementing retrogression forming of AA7075-T6 sheet are presented.