【摘要】 采用光学显微镜(OA)、扫描电镜(SEM)、透射电镜(TEM)等手段和电化学、浸蚀、慢应变速率拉伸(SSRT)等测试方法,研究不同固溶热处理制度对7050铝合金板材微观组织和腐蚀性能的影响。结果表明:单级固溶将η(MgZn2)相完全溶入Al基体中,而S(Al2CuMg)相仍然大量存在,固溶度低,时效后晶内析出密度低;双级固溶使S相部分溶解,合金晶粒长大,再结晶分数高;逐级固溶使η和S相完全溶解,合金充分回复,时效后晶内析出密度高,再结晶分数低;不同固溶+T6时效态合金的抗应力腐蚀性能从大到小依次为逐级固溶>双级固溶>单级固溶。更多还原

【Abstract】 The effects of different solution heat treatments on the microstructure and corrosion resistance of 7050 Al alloy hot-rolled plate were investigated by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscope(TEM),electrochemical measurements,immersion corrosion tests and slow strain rate techniques(SSRT).The results show that η(MgZn2) phase is fully dissolved into Al matrix after the single-step solution heat treatment,while S(Al2CuMg) phase isn′t dissolved at all.As a result,the supersaturation degree of the alloy is low and the precipitation density of second phase in the Al matrix after aging treatment is small.Through the two-step solution treatment,S phase is partially dissolved and the size of recrystallization grains in the alloys grows larger resulting in the increase of recrystallization volume fraction.By treating with step-to-step solution,η and S phase are completely dissolved into the matrix contributing to the high precipitation density in the Al matrix after aging treatment.Meanwhile,the alloy with low recrystallization fraction is obtained because of full recovery.The resistance to stress corrosion cracking(SCC) for the samples with solution and aging treatments decreases in the order: step-to-step solution > two-step solution > single-solution.更多还原