Abstract: Taking the pre-aged 7075 aluminum alloy sheet as experimental material, the uniaxial tension, tension-unloading, tension-compression and U-bending springback tests were conducted at room temperature and -196 °C. Combined with finite element simulation, the deformation and springback behavior at cryogenic temperature were analyzed. The results show that the pre-aged 7075 aluminum alloy exhibits the dual enhancement effect of enhanced elongation and hardening ability in uniaxial tension at cryogenic temperature. During tension-unloading tests, the cryogenic elastic modulus decays faster with strain. The early yielding and transient behavior are more prominent during tension-compression tests, which means the Bauschinger effect is enhanced at cryogenic temperature. Moreover, the cryogenic springback of the U-bending specimen is slightly larger than that at room temperature. Considering the difference between forward and reverse hardening, the initial Y-U model was modified with different hardening coefficients in forward and reverse loading. At cryogenic temperature, the modified Y-U model could both describe tension-compression curve better and have higher prediction accuracy for the springback of U-bending specimen.

Key words: cryogenic deformation, 7075 aluminum alloy, Bauschinger effect, hardening model, springback prediction