重固溶再时效对2040铝合金组织和性能的影响

Effect of re-solution and re-aging on microstructure and properties of 2040 aluminum alloy

在制动产生的高温环境下,飞机轮毂用2040合金性能会逐渐衰减。本文提出一种重固溶再时效的热处理方法用以恢复合金的性能,实现合金的回收再使用。首先,采用热暴露(200℃/100 h)方式来模拟制动过程中轮毂服役的高温环境,使合金失效;其次,设置未进行热暴露处理的合金作为对照,将2组合金一同进行重固溶再时效处理(510℃/1.5 h+165℃/15 h);最后,通过金相显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、电化学和晶间腐蚀等测试方法探究合金组织与性能的变化。研究结果表明:重固溶再时效处理使晶粒略微增大,晶内粗大的强化相消失,Ω相数量增多且分布均匀,失效的合金力学性能(313 MPa)恢复至原始T6态(448 MPa);重固溶处理使部分金属间化合物粒子(Al2Cu相和Al2CuMg相)发生回溶,减少了其周围溶质贫乏的腐蚀敏感区域;无沉淀析出带(PFZ)宽度变窄,减少了腐蚀裂纹扩展的通道。飞机轮毂用2040合金因受热失效后,重固溶再时效处理能够有效恢复合金的力学性能,同时还增强了耐腐蚀能力。

Under the high temperature environment generated by braking,the performance of 2040 alloy for aircraft wheel hub would gradually decay.In this paper,a heat treatment method of re-solution and re-aging was proposed to restore the performance of the alloy and achieve reusing.Firstly,heat exposure(200 ℃/100 h) was used to simulate the high temperature environment of the wheel hub during braking,so that the alloy failed.Secondly,the alloy without heat exposure treatment was set as a control way.The two groups of alloys were treated by re-solution and re-aging(510 ℃/1.5 h+165 ℃/15 h).Finally,the changes of microstructure and properties of the alloy were investigated by optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM),electrochemical and inter-granular corrosion test methods.The results show that the re-solution and re-aging treatment increases the grain size,the coarse strengthening phase in the grain disappears,the uniform distribution of Ω phase appears and the number increases,and the mechanical properties of the failed alloy(313 MPa) are restored to the original T6 state(448 MPa).Through re-solution treatment,the intermetallic compound particles(Al2Cu phase and Al2CuMg phase) in the microstructure are partially re-dissolved,which reduces the corrosion sensitive area with solute-poor.The width of the precipitation free zone(PFZ) becomes narrower,reducing the channel of corrosion crack propagation.In summary,after the failure of 2040 alloy for aircraft hub due to heat,the re-solution and re-aging treatment can effectively restore the mechanical properties of the alloy,and also enhance the corrosion resistance.