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利用动电位极化技术、慢应变速率拉伸试验(SSRT)以及扫描电镜(SEM)等方法研究了大港土壤环境中硫酸盐还原菌(SRB)对X80钢应力腐蚀开裂行为的影响及作用机理。结果表明:与无菌条件下相比,大港土壤模拟溶液中SRB的存在促进了X80管线钢的阳极溶解过程,诱发了金属的点蚀行为,增大了应力腐蚀开裂的机率。大港溶液中SRB数量越多,试样的点蚀电位越低,X80钢的应力腐蚀敏感性越大。当SRB生长4 d时,其菌量最大,此时试样断口形貌仍表现为韧性断裂特征;在SRB不同生长阶段下大港土壤模拟溶液中X80管线钢的应力腐蚀开裂机理为阳极溶解机制。
The effects of sulfate reducing bacteria (SRB) on the stress corrosion cracking behavior of X80 steel in the soil environment of Dagang were studied by using potentiodynamic polarization, slow strain rate tensile test (SSRT) and scanning electron microscopy (SEM). The results showed that the presence of SRB in soil simulated solution promoted the anodic dissolution process of X80 pipeline steel and induced the pitting corrosion of metal and increased the probability of stress corrosion cracking. The greater the amount of SRB in Dagang solution, the lower the pitting potential of the sample, the greater the stress corrosion susceptibility of X80 steel. When SRB was grown for 4 days, its strain was the largest. At this time, the fracture surface morphology of the SRB still showed ductile fracture. The mechanism of stress corrosion cracking of X80 pipeline steel was anodic dissolution mechanism in different growth stages of SRB.