Effect of heat treatment on the microstructure and mechanical properties of cryogenic rolling 2195 Al-Cu-Li alloy

摘要

Cryogenic deformation had been proved to promote the strength and toughness in several kinds of alloys. The microstructure responses and mechanical properties of cryogenic rolling 2195 Al-Cu-Li alloy after heat treatment were investigated systematically in this study. The annealed 2195 Al-Cu-Li alloy plates were subjected to cryogenic rolling to a reduction of 80% at -190 °C, followed by the solid solution at 540 °C for 2 h and aging treatment at 175 °C for different durations. Both the tensile strength and ductility of heat-treated specimen increased compared with the as-rolled sample, while the yield strength of the cryogenic rolling sample was higher anomaly. In addition, the tensile strength, yield strength, and elongation of the heat-treated samples increased firstly and then decreased with the increase of aging time. The number of T_1 phases was initially increased with the aging time extended to 12 h and decreased after the aging duration was increased to 16 h. While the number of θ' gradually decreases with aging time increased. Based on the precipitation kinetics, aging kinetics, and dislocation theory, a physically based model considering the variation of dislocation density and volume fraction of the T_1 phase and aging duration was established in this paper, which is in good agreement with the experimental data. Meanwhile, a strong connection between the dislocation density and fraction of the T_1 phase and aging duration is established.