取向对含钪2124铝合金抗应力腐蚀开裂行为的影响

Influence of sampling orientation on stress corrosion cracking resistant behavior of 2124 aluminum alloy containing Sc

采用光学显微镜和扫描电镜等研究新型含钪2124铝合金两种不同取向试样在3.5%NaCl(质量分数)溶液中的应力腐蚀开裂行为,并对裂纹尖端形貌和腐蚀形貌进行分析。结果表明:该铝合金在应力腐蚀时首先发生阳极溶解,裂纹尖端晶界处大量聚集的腐蚀产物产生的楔入力和外加应力的共同作用促使预制裂纹在腐蚀介质中进一步沿晶界向纵深方向扩展;两种取向试样在全浸腐蚀时均发生明显的晶间腐蚀,容易发生应力腐蚀开裂;得到了不同取向试样的应力腐蚀裂纹扩展规律及应力腐蚀强度因子门槛值,并探讨取向对应力腐蚀开裂行为的影响。

The stress corrosion cracking behavior of the novel 2124 aluminum alloy containing Sc with different sampling orientations in 3.5%NaCl（mass fraction） solution was studied by optical microscopy and scanning electron microscopy. Furthermore,the morphologies at the crack tip before and after corrosion were analyzed. The results show that the anodic dissolution occurs first during the stress corrosion,and the cooperation of the wedging action incured by the mass of corrosion products gathering at the grain boundaries and the applied stress drives the pre-cracks extending along the grain boundaries to the depth direction further in the corrosive medium. Obvious intergranular corrosion of the samples of the two orientations occurs under the total immersion corrosion and stress corrosion cracking takes places easily. The stress corrosion crack propagation law and the stress corrosion intensity factor threshold of the samples of different orientations are obtained. The effect of the sampling orientation on the stress corrosion cracking behavior was investigated.