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Influence of retrogression and reaging (RRA) heat treatment on microstructure, mechanical and chemi-cal behaviour of an Al-Zn-Mg alloy

2002; De Gruyter; Volume: 2; Linguagem: Inglês

2083-4799

Andrzej Zieliński, M. Warmuzek, А. Газда, E. Jezierska, J. Chrzanowski,

Metal Forming Simulation Techniques

The Al-Zn-Mg alloy of the T6 temper alone or followed by the retrogression and Reaging heat treatment was investigated. The mechanical properties were determined with the slow strain rate test in air or substitute sea water environments, and fracture energy, elongation and RA calculated. The fracture faces after the tensile tests were examined with the SEM. The microstructure and dislocation network were examined with the TEM. The heat treatment affected the investigated features: alloy subject only to the T6 temper demonstrated the best mechanical properties and the highest susceptibility to stress corrosion cracking. The increase in retrogression temperature and decrease in retrogression time positively influenced the resistance to SCC. The observed effects were explained by change in microstructure which caused changes in hydrogen diffusion and trapping, and then initiation and propagation of cracks..