摘要
采用光学显微镜(OM)和电化学测试等方法研究了X90管线钢及其焊缝的显微组织和在不同温度近中性模拟土壤溶液中电化学腐蚀行为,分析了温度对其电化学腐蚀行为的影响。结果表明:X90管线钢母材的显微组织为粒状贝氏体和少量多边形铁素体,焊缝的显微组织为针状铁素体和少量粒状贝氏体;随着测试温度的升高,母材和焊缝的开路电位向负方向移动,材料的热力学稳定性下降,腐蚀倾向增加;母材和焊缝的极化曲线具有阳极溶解特征,无明显的钝化区,随着测试温度的升高,母材和焊缝的腐蚀电流密度增大,极化电阻减小,耐蚀性下降;在相同测试温度下,焊缝的腐蚀速率大于母材的,说明焊缝的耐蚀性较差;在测试环境中,X90管线钢的腐蚀过程主要受阴极扩散控制。
The microstructure and electrochemical corrosion behavior of X90 pipeline steel and its weld in near neutral simulated soil solution were investigated by optical microscopy(OM)and electrochemical testing at different temperatures.The effects of temperature on electrochemical corrosion behavior were analyzed.The results show that the microstructure of the base metal of X90 pipeline steel consisted of granular bainite and a small amount of polygonal ferrite,the microstructure of the weld consisted of acicular ferrite and a small amount of granular bainite.With the increase of temperature,the open circuit potentials of the base metal and weld shifted negatively,the thermodynamic stability decreased,and the corrosion tendency increased for the materials.The polarization curves of the metal base and weld displayed typical characteristic of anodic dissolution without remarkable passivation region.With the increase of temperature,the corrosion current densities of the base metal and weld increased,the polarization resistance decreased,and the corrosion resistance decreased.At the same temperature the corrosion rate of the weld was higher than that of the base metal,so the weld had worse corrosion resistance.The corrosion of X90 pipeline steel was controlled by cathodic diffusion process in the test environment.
作者
梁锟
雒设计
徐飞
LIANG Kun;LUO Sheji;XU Fei(Architecture Zabor University of Shaanxi Province,Xi’an 710068,China;School of Materials Science and Engineering,Xi′an Shiyou University,Xi’an 710065,China;Downhole Technology Service Branch of CNPC Bohai Drilling Engineering Limited Company,Tianjin 300283,China)
出处
《腐蚀与防护》
CAS
北大核心
2020年第8期23-27,69,共6页
Corrosion & Protection
关键词
X90管线钢
焊缝
温度
电化学腐蚀
耐蚀性
X90pipeline steel
weld
temperature
electrochemical corrosion
corrosion resistance
