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通过慢拉伸应力腐蚀试验机、电化学工作站和扫描电子显微镜(SEM)等手段,研究挤压态镁合金AZ31B在pH=2、7和12的NaCl溶液中的应力腐蚀行为。结果表明,随pH值增大,AZ31B静态腐蚀速率和应力腐蚀敏感性均降低,这是由于碱性溶液更有利于Mg(OH)2表面保护膜的形成。应力腐蚀试验中点蚀形成主要裂纹源,拉伸断口分析表明应力腐蚀具有多裂纹源特征,应力加速腐蚀进程,断裂方式属于穿晶解理断裂。
The stress corrosion behavior of extruded magnesium alloy AZ31B in NaCl solution at pH = 2, 7 and 12 was studied by means of slow tensile stress corrosion tester, electrochemical workstation and scanning electron microscope (SEM). The results show that the static corrosion rate and stress corrosion sensitivity of AZ31B decrease with the increase of pH, which is attributed to the fact that alkaline solution is more favorable for the formation of Mg (OH) 2 surface protective film. The main source of cracks is pitting corrosion in stress corrosion test. The analysis of tensile fracture shows that stress corrosion has multi-crack source characteristics, stress accelerates the corrosion process, and the fracture mode belongs to transgranular cleavage fracture.