Microstructure and properties of an Al-Zn-Mg-Cu alloy pre-stretched plate under various ageing conditions
来源期刊：Rare Metals2008年第6期
论文作者：DONG Xiaoruia and LI Zhihuib a College of Mechatronic Engineering, North University of China, Taiyuan , China b State Key Laboratory for Fabrication and Processing of Nonferrous Metals, General Research Institute for Nonferrous Metals, Beijing , China
文章页码：652 - 656
摘 要：The microstructures after various ageing treatments and their relation to the strength, fracture toughness, and corrosion behavior of an Al-Zn-Mg-Cu alloy pre-stretched plate were investigated. The results show that retrogression and reaging （RRA） treatment led to a combina- tion of high strength and stress corrosion cracking （SCC） resistance of the alloy. The TEM microstructure of the RRA-treated alloy is a dis- tribution of very fine precipitates in the aluminum matrix grains, similar to that obtained under T6 condition, and the distribution of coarse η MgZn2 precipitates on the grain boundaries similar to that obtained by T7 temper. SEM observations revealed that most of the intergranular fracture characteristics were present on the fracture surface of both the T6 and RRA-treated specimens. On the contrary, the fractographs of the T7 treated specimens mainly consisted of dimple-type ductile transgranular fracture with minor intergranular cracking.
DONG Xiaoruia and LI Zhihuib a College of Mechatronic Engineering, North University of China, Taiyuan 030051, China b State Key Laboratory for Fabrication and Processing of Nonferrous Metals, General Research Institute for Nonferrous Metals, Beijing 100088, China
摘 要：The microstructures after various ageing treatments and their relation to the strength, fracture toughness, and corrosion behavior of an Al-Zn-Mg-Cu alloy pre-stretched plate were investigated. The results show that retrogression and reaging （RRA） treatment led to a combina- tion of high strength and stress corrosion cracking （SCC） resistance of the alloy. The TEM microstructure of the RRA-treated alloy is a dis- tribution of very fine precipitates in the aluminum matrix grains, similar to that obtained under T6 condition, and the distribution of coarse η MgZn2 precipitates on the grain boundaries similar to that obtained by T7 temper. SEM observations revealed that most of the intergranular fracture characteristics were present on the fracture surface of both the T6 and RRA-treated specimens. On the contrary, the fractographs of the T7 treated specimens mainly consisted of dimple-type ductile transgranular fracture with minor intergranular cracking.
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