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采用电化学极化手段和慢应变速率拉伸试验,结合扫描电镜观察合金断口形貌,研究了外加电位对7A52铝合金应力腐蚀开裂敏感性的影响。研究结果表明:合金在3.5%NaCl溶液中的应力腐蚀开裂敏感性与外加电位有强烈的相关性,开裂敏感性在外加电位为-0.95 V时最低,外加电位起到阴极保护的作用;在外加电位为-1 V时有所升高,但仍然低于开路电位条件下的敏感性;在-1.1 V时最高,应力腐蚀过程以氢脆为主;在-1.2 V时又有所降低,阴极析出的氢以气态逸出而降低应力腐蚀开裂敏感性。
The effects of applied potential on the stress corrosion cracking resistance of 7A52 aluminum alloy were studied by means of electrochemical polarization and slow strain rate tensile test combined with scanning electron microscopy. The results show that there is a strong correlation between the stress corrosion cracking susceptibility and the applied potential in 3.5% NaCl solution. The dehiscence sensitivity is lowest when the applied potential is -0.95 V, and the applied potential plays the role of cathodic protection. The potential increased at -1 V, but still lower than that under open-circuit potential. At -1.1 V, the stress corrosion process was dominated by hydrogen embrittlement and decreased at -1.2 V. The cathode Precipitated hydrogen escapes in the gaseous state to reduce stress corrosion cracking susceptibility.