Warm Forming and Paint Bake Response of AW-7xxx Sheet in Various Tempers

Abstract

In this paper, we have investigated AW-7921 in various tempers - specifically under aged T4P1-and T4P2-tempers, naturally aged T4 and peak-aged T6-tempers - for their warm formability at 230°C and paint baking response through one step and five step paint baking treatments. It was found that warm formability depends on dynamic recovery and dissolution of precipitates. However, the response to paint baking was dependent on the stability of the precipitates against coarsening. Of the tempers investigated the T4-temper exhibited the best combination of formability and paint baking response. This study also indicated that we can achieve much better performance in the warm forming processing chain by optimization of the temper and paint baking heat treatment procedure.