回归时间对7150铝合金力学性能与组织的影响  

Influence of Retrogression Time on Mechanical Properties and Microstructure of 7150 Aluminum Alloy

作　　者：张研 邓运来 范世通[2] 龙涛[2] ZHANG Yan;DENG Yun-lai;FAN Shi-tong;LONG Tao(Light Alloy Research Institute,Central South University,Changsha 410083,China;School of Materials Science andEngineering,Central South University,Changsha 410083,China)

机构地区：[1]中南大学轻合金研究院,长沙410083 [2]中南大学材料科学与工程学院,长沙410083

出　　处：《材料工程》2018年第12期131-136,共6页Journal of Materials Engineering

基　　金：国家重点基础研究发展计划(2012CB619500);国家重点研发计划(2016YFB0300901);国家自然科学基金(51375503);广西重大专项计划(14122001-5)

摘　　要：采用硬度、常温拉伸、恒载荷拉伸、剥落腐蚀及透射电镜等方法研究回归时效时间对7150-T77铝合金性能和组织的影响。结果表明:随回归时效时间的延长,晶内η′相先回溶再重新析出η相,并不断粗化,导致合金最终力学性能先升高后降低,η′相回溶与η相析出的临界时间为30min,此时合金最终力学性能最高;晶界η相不断粗化且不连续,大幅提高合金的抗腐蚀性能;再时效阶段存在硬度峰值,且回归时效时间越长,达到硬度峰值时间越短。对比实验表明,较优的T77制度为105℃/17h+190℃/30min+120℃/23h,其抗拉强度(σb)、屈服强度(σ0.2)和伸长率(δ)分别为608,544MPa和10.4%,剥落腐蚀评级为EA级,恒载荷实验中抗拉强度和伸长率损失分别为4.9%和5.0%。The influence of the retrogression time on properties and microstructure of 7150-T77 aluminum alloy was studied by hardness testing, tensile property testing, exfoliation corrosion test and TEM. Results indicate that the matrix precipitated η′ phase re-dissolves first, and then η phase re-precipitates and becomes coarsened with the extending of retrogression time. The ultimate mechanical properties increase first then decrease as retrogression time increases. The critical time of the η′ phase re-dissolution and the η phase precipitation is 30min, At this point, alloys have the highest ultimate mechanical properties, and the grain boundary precipitated η phase becomes coarsened and discontinuous, leading to lower mechanical properties and better corrosion resistance, peak hardness exists at re-aging stage. With the retrogression time extending, the time for the alloy to reach the peak hardness becomes shorter. Optimal T77 aging treatment is 105℃/17h＋190℃/30min＋120℃/23h. With this treatment, the ultimate tensile strength （ σ b ）, yield strength （ σ 0.2 ） and elongation （ δ ） are 608,544MPa and 10.4%, respectively, the exfoliation corrosion test gets EA level, the σ b and δ loss in constant loading tensile testing is 4.9% and 5.0%, respectively.

关 键 词：7150铝合金 三级时效 回归时间 力学性能 微观组织 

分 类 号：TG146.21[一般工业技术—材料科学与工程]