Influence of retrogression temperature and time on the mechanical properties and exfoliation corrosion behavior of aluminium alloy AA7150

By Jin-feng Li, Nick Birbilis, Chengbo Li, Z. Jia, B. Cai, Zi-Qiao Zheng. 2009

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Abstract The tensile properties, exfoliation corrosion behavior and microstructures of the retrogression and re-aging (RRA) treated aluminum (Al) alloy AA7150 were studied. AA7150 was retrogressed at different temperatures (175 °C, 185 °C and 195 °C) for various times. It is found that as the hardness of the retrogressed AA7150 approaches the near-peak condition, the corresponding RRA treated AA7150 possesses good exfoliation corrosion resistance without strength loss. By retrogressing at 175 °C, the retrogression time can be extended to 3 h, the RRA treated AA7150 possesses a strength as high as that of conventional AA7150-T6, and its exfoliation corrosion resistance is in the vicinity to that of AA7150-T73. This enhanced exfoliation corrosion resistance was associated with the more separated η precipitates at the grain boundary. AA7150-T6 is mainly strengthened by fine GP zones with high number density, while the intra-grain micro-structure of AA7150-RRA retrogressed at 175 °C for 3 h is characterized by relatively coarse η′ precipitates.

Subfields: Aerospace Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/446073bfdcca920d51f26a953c51aa9ae0c93c66