Annealing of flexible-rolled Al–5.5 wt%Mg alloy sheets for auto body application

Tailor rolled blanks (TRB) of Al–5.5 wt%Mg alloy were fabricated by flexible rolling process, the thickness reduction of thin parts did not exceed 50%. In order to optimize heat treatment condition for increasing formability of TRB sheets, annealing treatment of the sheet having different rolling rate was conducted at the temperature range of 350–450 °C for 1 h. The microstructure and tensile properties of the sheets were evaluated and the formability of the sheets was investigated by evaluating plastic anisotropy (R) and punch stretching test. The Al–5.5 wt%Mg alloy sheets annealed at 400 °C for 60 min showed high strain hardening and low plastic anisotropy at the whole range of reduction rate (0–45%).