Zhang Ci, Ran Minrui, Wang Yao, Zheng Wenyue
National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083, China.
South China Branch of National Petroleum and Natural Gas Pipe Network Group, Guangzhou 510620, China.
Materials (Basel). 2022 Jun 21;15(13):4372. doi: 10.3390/ma15134372.
The corrosion and stress corrosion cracking (SCC) behaviors of 20#, X60, and X80 pipeline steels in a near-neutral pH environment were investigated by means of electrochemical measurement, immersion test, and interrupted slow strain rate tensile (SSRT) test. The propensity for SCC, as indicated by the stress threshold value for crack initiation, was found to be dependent on the type of steel microstructure. Cracks were initiated in the high-strength steel X80 at a stress less than its yield strength, whereas in the other lower-grade steels, the initiation of cracks occurred after the yielding point. The threshold stress of SCC initiation in the near-neutral pH environment for 20#, X60, and X80 steels were 130.64% σ, 106.79% σ, and 86.92% σ, respectively. The SCC of 20# and X60 were characterized by the formation of transgranular and intergranular cracks, while X80 steel was only by transgranular cracking. The occurrence of corrosion had a great effect on crack initiation and the growth at the later stage. The latter involved hydrogen effects. A correlation between SCC sensitivity and the yield strength of the steel has been identified.
通过电化学测量、浸泡试验和间断慢应变速率拉伸（SSRT）试验，研究了20#、X60和X80管线钢在近中性pH环境中的腐蚀和应力腐蚀开裂（SCC）行为。由裂纹萌生应力阈值表示的SCC倾向被发现取决于钢的微观结构类型。高强度钢X80在应力小于其屈服强度时就开始产生裂纹，而在其他低等级钢中，裂纹在屈服点之后才开始萌生。20#、X60和X80钢在近中性pH环境中SCC萌生的阈值应力分别为130.64%σ、106.79%σ和86.92%σ。20#和X60的SCC特征是穿晶裂纹和沿晶裂纹的形成，而X80钢仅为穿晶开裂。腐蚀的发生对裂纹萌生以及后期的扩展有很大影响。后期扩展涉及氢效应。已确定SCC敏感性与钢的屈服强度之间存在相关性。
