第二级固溶温度对7050铝合金组织和性能的影响

Influence of the second stage solution temperature on microstructure and properties of aluminum alloy 7050

为了研究双级固溶、双级时效处理下的固溶温度对7050铝合金的影响,采用常温拉伸、晶间腐蚀等方法研究了双级固溶、双级时效热处理制度下第二级固溶温度对7050铝合金组织和性能的影响。结果表明,随着第二级固溶温度的升高合金晶粒尺寸逐渐长大,残余第二相不断固溶。495℃时的S相基本固溶,残余第二相体积分数为0.19%,晶粒尺寸较小,合金屈服强度R_(eL)为655 MPa,抗拉强度R_m为694 MPa,伸长率A_(50 mm)为14.40%,综合力学性能最好。温度过高时合金发生过烧,性能减弱。晶间腐蚀从合金外部晶界开始向内部扩展,耐晶间腐蚀性能随着残余第二相的逐渐固溶而增强。

In order to research the influence of solid solution temperature on aluminum alloy 7050 under two-stage solution and two-stage aging, the effect of the second levels solid solution temperature on microstructure and properties of aluminum alloy 7050 with two-stage so- lution and two-stage aging heat treatment was studied by tensile test and intergranular corrosion. The results show that the grain size of the alloy increases gradually with the increase of the second levels solid solution temperature, and solid solution of the second phase contin- ues. At temperature of 495℃, the S plase is solid soluted basically, volume fraction of the residual second phase particles is 0. 19% , and grain size is smaller with alloy ReL （yield strength） is 655 MPa, Rm （ tensile strength） is 694 MPa, A50mm （elongation） is 14. 40% , which shows the best comprehensive performance. When the temperature is too high, alloy performance weakens because of the over burn- ing. The beginning of intergranular corrosion extends from the outer grain boundary of alloy to inner of the grain, and the corrosion resistance of the alloy increases with the decrease of the residual second phase.