强化固溶对7055铝合金力学性能和断裂行为的影响

The effect of promotively-solutionizing treatment on the mechanical properties and fracture of ultra high strength 7055 aluminum alloys

残余可溶结晶相颗粒是制约高强度铝合金力学性能的重要因素 .作者通过改变固溶热处理条件并结合金相组织观察和断口分析研究了强化固溶对提高 70 5 5铝合金力学性能的作用 .结果表明 :采取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 70 5 5合金的屈服强度和抗拉强度分别达 715MPa和 75 0MPa,且延伸率约为 10 % ;微量元素Zr比Cr更有利于提高 70 5 5合金的力学性能 ,且在强化固溶条件下 ,提高效果更加明显 .通过断口分析显示 ,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 remaining constitute particles deteriorate the comprehensive properties of high strength aluminum alloys. The effects of promotively solutionizing of soluble remaining constituent phases on the microstructure and mechanical properties of 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 7055 alloys. By promotively solutionizing, the yield strength and ultimate tensile strength of 7055 alloy can rise to 715 MPa and 750 MPa respectively, remaining about 10% elongation. Zr addition is more beneficial to the strength of 7055 alloy than Cr. Fractography demonstrates that the fracture of 7055 alloys is in transgranular/intergranular mixed mode. By promotively solutionizing, the transgranular dimpled rupture initiated from remaining constituents decreases , and intergranular rupture increases. [