Two-stage double peaks ageing and its effect on stress corrosion cracking susceptibility of Al-Zn-Mg alloy
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2018年第7期
论文作者：Y.L.Wang H.C.Jiang Z.M.Li D.S.Yan D.Zhang L.J.Rong
文章页码：1250 - 1257
摘 要：Different artificial two-stage ageing behaviors and their effect on stress corrosion cracking（SCC） susceptibility of Al-Zn-Mg alloy have been investigated. The experimental results show that two hardness peaks present on the second-stage ageing-hardening curve when the first-stage ageing is dealt with comparatively lower temperature than the conventional one. The first peak is caused by dispersive and evenly distributed G.P. zones, while η’ phases and coarsened G.P. zones contribute to the second peak. Tensile strength of experimental alloy raises 9.6%（33.2 MPa） and SCC susceptibility decreases 38.9% by applying the second peak ageing regime instead of conventional T73. Al-Zn-Mg alloy obtains high strength and SCC resistance due to its finely dispersive matrix precipitates（MPts）, coarsened and discontinuous grain boundary precipitates（GBPs）, as well as the narrow precipitate free zone（PFZ） in the second peak ageing condition.
Y.L.Wang1,2，H.C.Jiang1，Z.M.Li1，D.S.Yan1，D.Zhang1,2，L.J.Rong1
1. CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences2. School of Materials Science and Engineering, University of Science and Technology of China
摘 要：Different artificial two-stage ageing behaviors and their effect on stress corrosion cracking（SCC） susceptibility of Al-Zn-Mg alloy have been investigated. The experimental results show that two hardness peaks present on the second-stage ageing-hardening curve when the first-stage ageing is dealt with comparatively lower temperature than the conventional one. The first peak is caused by dispersive and evenly distributed G.P. zones, while η’ phases and coarsened G.P. zones contribute to the second peak. Tensile strength of experimental alloy raises 9.6%（33.2 MPa） and SCC susceptibility decreases 38.9% by applying the second peak ageing regime instead of conventional T73. Al-Zn-Mg alloy obtains high strength and SCC resistance due to its finely dispersive matrix precipitates（MPts）, coarsened and discontinuous grain boundary precipitates（GBPs）, as well as the narrow precipitate free zone（PFZ） in the second peak ageing condition.
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