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通过慢应变速率拉伸试验方法,研究了在室温下不同pH值的3.5 mass%NaCl溶液对CLAM钢扩散连接接头应力腐蚀开裂行为的影响。通过光学显微镜对试样的母材和接头处的微观组织进行了观察,并利用扫描电镜对试样断口形貌进行观察与分析,判断试样在不同pH值的3.5 mass%NaCl溶液中的应力腐蚀敏感性大小。通过观察宏观断口发现:无论在酸性、碱性或中性溶液中,试样均在母材部分断裂,且均出现了不同程度的颈缩现象。SSRT结果以及断口形貌分析结果表明:在室温下,CLAM钢在酸性溶液中的应力腐蚀开裂敏感性较大,其应力腐蚀机理为氢致开裂型;在中性溶液中的应力腐蚀开裂敏感性居中,其应力腐蚀机理为阳极溶解和氢致开裂共同作用;在碱性溶液中的应力腐蚀开裂敏感性较小。
The effects of 3.5 mass% NaCl solution at different pH values on the stress corrosion cracking behavior of diffusion bonded joints of CLAM steel were studied by slow strain rate tensile test. The microstructure of the base metal and the joint of the sample was observed by optical microscope. The fracture morphology of the sample was observed and analyzed by scanning electron microscope to determine the stress of the sample in 3.5 mass% NaCl solution with different pH Corrosion sensitivity size. By observing the macroscopic fracture, it was found that the samples were all broken in the base metal in acidic, alkaline or neutral solution, and all showed different degrees of necking. The results of SSRT and the fracture surface analysis show that the stress corrosion cracking of CLAM steel is sensitive to acidic solution at room temperature, and its stress corrosion mechanism is hydrogen induced cracking. In the neutral solution, the stress corrosion cracking Center, the stress corrosion mechanism for the anodic dissolution and hydrogen induced cracking together; in alkaline solution stress corrosion cracking less sensitive.