Study on removal of residual stress of 7A60 aluminium alloy by liquid nitrogen cryogenic technology

7A60 aluminium alloy obtained high strength and toughness through solution strengthening, at the same time, it also produced serious quenching residual stress. This paper introduces a residual stress relief technology-liquid nitrogen cryogenic treatment technology. In order to verify the effectiveness of this technology, take 7A60 aluminium alloy was an example, the technological route of cryogenic treatment was worked out and the comparative test was carried out. Then the surface residual stress, physical and chemical properties, limit speed and processing tests of 7A60 aluminium alloy were carried out, and then compared with the blank without cryogenic treatment. The experimental results show that cryogenic treatment can effectively reduce the peak residual stress of 7A60 aluminum alloy, and make the distribution of residual stress more uniform, thus effectively controlling the processing deformation of thin-walled parts. At the same time, cryogenic treatment has no effect on the mechanical properties, chemical composition, microstructures, hardness, limit speed and so on. (authors)