Retrogression and reaging — aluminum alloy AA7012

Retrogression and reaging (RRA) is of interest to the automotive industry for manufacturing components of high-strength aluminum alloys. This study describes obtaining the retrogression and reaging curve for the aluminum alloy AA7012-T6 (Al–Zn–Mg–Cu) — UNS A97012. The RRA heat treatment consists of two stages: the first stage is retrogression, which was carried out on samples in the T6 hardening condition for a time ranging from 5 s to 4 h at different temperatures: 180 °C, 210 °C, and 240 °C. The second stage, reaging, was conducted at 120 °C for 24 h (process parameters for obtaining the T6 temper). The RRA curve was obtained by measuring hardness Vickers (HV). The samples were also evaluated for electrical conductivity (%IACS — International Annealed Copper Standard). The best response for the RRA curve was obtained with retrogression at 180 °C/1 h and reaging at 120 °C for 24 h. The increase in hardness (HV) obtained with RRA 180 °C/1 h and reaged at 120 °C/24 h was 19%.