The effect of two specific solution heat treatment procedures on the corrosion and stress corrosion cracking (SCC) susceptibility of an as-rolled Al-Zn-Mg-Cu alloy was investigated. It is shown that for a stepped solution treatment with a final temperature of 495°C, the SCC resistance of subsequently retrogressed and re-aged (RRA) samples is remarkably improved compared with that of samples solution-treated at a stationary temperature of 475°C. Since the investigated alloy is probably only partially homogenized or cooled with a very slow industrial cooling rate after homogenization, the mechanistic aspects of this are related to the dissolution of Al2CuMg and the Cu content in the grain boundary precipitates after the RRA treatment.

Subject
Test methods, Intergranular stress corrosion cracking, Precipitates, Dissolution, Copper alloys, Cracking resistance, Sodium chloride solution, Immersion, Corrosion resistance, Aluminum alloys, Grain boundary, Stress corrosion cracking, Samples
Keywords:
7xxx series, aluminum, corrosion, solution heat treatment, stress corrosion cracking
© 2012 NACE International
2012
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