After solution treatment, 7075 aluminum plates were quenched by immersion and spraying separately, then treated by pre-stretching process. Residual stresses of immerging quenched plates and spraying quenched plates, as well as stresses of corresponding pre-stretched plates were measured with crack compliance method.
The influence of different quenching techniques on residual stress developing and redistributing after pre-stretching of 7075 aluminum alloy plate were studied. The results show that the faster the quenching speed, the larger the residual stress of aluminum alloy thick-plate. The compressive stress and tensile stress of immerging quenched plates are 61% and 73.6% larger than those of spraying quenched plates, respectively, and after pre-stretching process, the residual stress decreases to the range of -20-20 MPa, which satisfies the machining requirement. Furthermore, for these stretching ratios of 1.8%, 2.2% and 2.5%, the differences of the residual stress relieving effect are quite small.