强化固溶对Al-Zn-Mg-Cu合金力学性能和断裂行为的影响

EFFECT OF PROMOTIVELY-SOLUTIONIZING HEAT TREATMENT ON THE MECHANICAL PROPERTIES AND FRACTURE BEHAVIOR OF Al-Zn-Mg-Cu ALLOYS

研究了强化固溶对提高７０７５和７０５５铝合金力学性能的效果。结果表明，逐步升温固溶处理可使最终固溶温度超过多相共晶温度而不产生过烧组织，提高残余可溶结晶相的固溶程度和合金力学性能。强化固溶的７０７５和７０５５合金的抗拉强度分别达到６６０和７５０ＭＰａ；且延伸率保持约１０％．一般固溶７０５５合金的强度仅与强化固溶７０７５合金的强度相当。断口分析显示，两种合金的断裂属晶内韧窝断裂与沿晶断裂的混合断裂。强化固溶后，残余结晶相引起的晶内韧窝断裂减少。

The effects of promotively-solutionizing of soluble remaining constituent phases on the microstructure and mechanical properties of 7075 and 7055 alloys were studied. The results show that the temperature-incremental solutionizing heat treatment can make the solutionizing temperature limit higher than the multi-phase eutectic temperature without the formation of overheated structure, and effectively promote the solutionizing and improve the mechanical properties of 7075 and 7055 alloys. By promotively-solutionizing, the ultimate tensile strengths of 7075 and 7055 alloys can rise to 660 MPa and 750 MPa respectively, with remaining elongation of about 10%. Fractography demonstrates that the fractures of 7075 and 7055 alloys are all in transgranular/intergranular mixed mode. By promotively-solutionizing, the transgranular dimpled rupture initiated from remaining constituents decreases, and intergranular rupture increases.