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用慢应变速率拉伸测试、金相(OM)、扫描电镜(SEM)及透射电镜(TEM)分析等方法研究了Al-3.88Cu-1.18Mg-0.31Mn铝合金在T6时效状态下的应力腐蚀开裂(SCC)行为。结果表明:随着时效时间的延长,合金的应力腐蚀开裂敏感性逐渐降低。合金应力腐蚀与晶间腐蚀具有正相关性,其本质是晶界与晶内存在电位差,形成电偶腐蚀,在应力作用下,导致晶界连续腐蚀。在时效过程中,晶界S’(S)相由连续分布逐渐转变为断续分布,晶内析出相由GPB区逐渐转变为S’(S)相,并形成PFZ。这样的微观组织转变使合金应力腐蚀开裂敏感性随着时效的进行逐渐降低。
The stress corrosion of Al-3.88Cu-1.18Mg-0.31Mn aluminum alloy under T6 aging was studied by slow strain rate tensile test, OM, SEM and TEM. Cracking (SCC) behavior. The results show that with the aging time, the susceptibility to stress corrosion cracking of the alloy gradually decreases. There is a positive correlation between stress corrosion and intergranular corrosion. The essence is the potential difference between the grain boundary and the crystal to form galvanic corrosion, which leads to continuous grain boundary corrosion under the stress. During the aging process, the grain boundary S ’(S) phase gradually changes from a continuous distribution to a discontinuous distribution, and the precipitates in the grain gradually transform from GPB to S’ (S) phase and form PFZ. Such a microstructure change makes the stress corrosion cracking resistance of the alloy gradually decrease with aging.