Determining a Retrogression Heat Treatment to Apply During Warm Forming of a High Strength Aluminum AA7075 Sheet Material

摘要

Combining retrogression heat treatment with simultaneous warm forming provides an opportunity to significantly increase the formability of high-strength aluminum alloy AA7075-T6 sheet material while subsequently regaining nearly peak-aged strength through a single reaging treatment. This new technological approach to forming high-strength aluminum alloy sheet is termed retrogression forming. Times and temperatures suitable to the retrogression forming of AA7075-T6 sheet material are examined. Differential scanning calorimetry is used to determine the activation energy associated with precipitate dissolution during retrogression. Heat treating experiments determine the changes in hardness during retrogression as a function of temperature and time. The concept of temperature-compensated time is used to construct a master curve that predicts appropriate retrogression forming conditions.