Cryogenic formability of a solution-treated aluminum alloy sheet at low temperatures

In this paper, the analysis of the necking and limit strains of a solution-treated aluminum alloy sheet at extreme low temperatures is performed using a newly-designed test apparatus equipped with the digital image correlation (DIC) device. The forming limit diagram (FLD) and forming limit stress diagram (FLSD) ductile fracture models were used to predict the drawing limit and fracture resistance capacity of an Al-Cu-Mn alloy sheet under complex stress at room temperature (RT) and -160 degrees C. It was found that the FLD0 value at -196 degrees C increased to 0.32 as compared to 0.23 at RT. The Al-Cu-Mn alloy sheets at -160 degrees C and -196 degrees C were found to have significantly higher limit strains than those at RT. The drawing height and limit major strain at the round corner of the cryogenic deep-drawn cups were found to be increased by 21.3 % and 9.7 %, respectively, as compared to those at RT. Moreover, a larger necking amount and higher fracture resistance of the Al-Cu-Mn alloy sheet could be achieved during cryogenic deformations. The obtained cryogenic FLDs and FLSDs can be used to accurately predict the damage evolution and failure occurrence for the forming of complex-shaped aluminum alloy components at low temperatures.