高温短时固溶处理对超高强Al-Zn-Mg-Cu合金锻件组织与性能的影响

Effect of high-temperature short-time solution treatment on microstructure and properties of ultra-high strength Al-Zn-Mg-Cu alloy forging

采用光学显微镜、扫描电镜和拉伸试验机研究了高温短时固溶处理温度(475~480℃)与时间(0~7 min)对高合金化Al-Zn-Mg-Cu合金锻件组织与性能的影响。结果表明,高温短时固溶处理可有效提高时效态Al-Zn-Mg-Cu合金锻件的抗拉强度及断后伸长率。随着温度或时间的增加,晶界粗大残留第二相逐渐回溶至铝基体,当温度过高或时间过长时,等轴状晶粒发生粗化,组织发生过烧现象。经对比分析并结合实际生产状况,确定最适合的高温短时固溶处理制度为475℃×3 min。采用此制度时锻件45°方向抗拉强度最低,为685 MPa, LT向断后伸长率最低,为4.7%。

Effect of high-temperature short-time solution treatment(temperature of 475-480 ℃ and time of 0-7 min) on microstructure and properties of high alloying Al-Zn-Mg-Cu alloy forging was studied by means of optical microscope, scanning electron microscope and room temperature tensile test. The results show that high-temperature short-time solution treatment can effectively improve the tensile strength and elongation of as-aged Al-Zn-Mg-Cu alloy forging. With the increase of temperature or time, the coarse retained second phase at the grain boundary gradually dissolves back into the aluminum matrix. When the temperature is too high or the time is too long, the equiaxed grains coarsen and the microstructure burns over. Through comparative analysis and combined with the actual production situation, it is determined that the most suitable high-temperature short-time solution treatment is 475 ℃ for 3 min, under which the minimum tensile strength of the forging is 680 MPa in the 45° direction and the lowest elongation is 4.7% in LT direction.