时效工艺对1933铝合金锻件腐蚀性能的影响

Effects of aging treatment on corrosion properties of 1933 aluminum alloy forging

采用金相显微镜(OM)、透射电镜(TEM)、慢应变速率拉伸(SSRT)、双悬臂梁实验(DCB)、晶间腐蚀实验和剥落腐蚀实验研究时效工艺对1933铝合金锻件抗应力腐蚀(SCC)、抗晶间腐蚀(IGC)和抗剥落腐蚀(EC)性能的影响。结果表明:在T6(120℃,24 h)时效状态下,1933铝合金锻件的应力腐蚀敏感性最强,应力腐蚀临界应力强度因子KISCC仅为8.95 MPa.m1/2。经(110℃,6 h)+(160℃,8 h)和(110℃,12 h)+(170℃,8 h)双级时效后,KISCC分别上升至23.84和27.56 MPa.m1/2,锻件的抗应力腐蚀性能显著提高。而经(110℃,12 h)+(180℃,6 h)时效后,抗应力腐蚀性能的提高伴随着较大幅度的强度损失和塑性损失。锻件在各时效状态下,晶间腐蚀形式为点蚀,具有良好的抗晶间腐蚀性能。同时,锻件具有良好的抗剥落腐蚀性能。T6时效时,锻件的剥蚀等级为EC级;经双级时效后,其剥蚀等级均在EA+级以上。

The effects of aging treatment on the stress corrosion cracking resistance,intergranular corrosion（EC） resistance and exfoliation corrosion resistance of 1933 aluminum alloy forging were investigated by means of optimal microscopy（OM）,transmission electron microscopy（TEM）,slow strain rate testing（SSRT）,double-cantilever-beam（DCB） experiment,intergranular corrosion（IGC） and EC experiments.The results show that the 1933 aluminum alloy forging under T6（120 ℃,24 h） aging treatment reveals the strongest stress corrosion cracking sensitivity and the critical stress intensity factor KISCC is only 8.95 MPa-m1/2.After aging treatment at（110 ℃,6 h）＋（160 ℃,8 h） and（110 ℃,12 H）＋（170 ℃,8 h）,KISCC is elevated to 23.84 and 27.56 MPa-m1/2,respectively,which indicates higher stress corrosion cracking resistance.Accompanying the improvement of stress corrosion resistance,the strength loss and plasticity loss decrease sharply when the forging is aging-treated at（110 ℃,12 h）＋（180 ℃,6 h）.The forging has excellent intergranular corrosion resistance under all aging treatments and the forms of corrosion are all pit corrosion.Meanwhile,the exfoliation corrosion resistance of the forging is also very good.The level of exfoliation corrosion is EC when the forging is under T6 aging treatment.After duplex aging,the level of exfoliation corrosion for the forging is EA＋.