Reducing the susceptibility of alloys, particularly aluminium alloys, to stress corrosion cracking

摘要: A method is described of thermally treating the 7,000 series aluminum alloys that have been subjected to a solution heat treatment at high temperature and then an ageing lower temperature, thereby hardening alloy but likewise producing therein susceptibility stress-corrosion cracking. The novel comprises steps (1) subjecting retrogression for short period time above age-hardening below (2) subsequently re-ageing substantially longer alloy. This reduces cracking while retaining its original strength.