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目前对于阴极极化条件下管线钢发生点蚀的特征和机理研究不多。采用光学显微镜、扫描电子显微镜(SEM)和阴极极化技术,研究了X80钢在3.5%Na Cl溶液中不同阴极极化电位下点腐蚀起始与特征。结果表明:阴极极化条件下,点腐蚀易在非金属夹杂物边缘处萌生并沿基体扩展。当阴极极化电位为-850 m V(vs CSE,下同)和-900 m V时,基体和夹杂物周围均发现有点蚀出现;-1 000 m V时,点蚀仅出现在非金属夹杂物周围;当极化电位提升到-1 200 m V时,试样表面未发现明显腐蚀。
At present, there are not many studies on the characteristics and mechanism of pitting corrosion in pipeline steel under cathodic polarization. The onset and characteristics of pitting corrosion under different cathodic polarization potentials of X80 steel in 3.5% NaCl solution were investigated by optical microscope, scanning electron microscopy (SEM) and cathodic polarization technique. The results show that under the condition of cathodic polarization, pitting corrosion tends to initiate at the edge of non-metallic inclusions and expand along the matrix. When the cathodic polarization potential is -850 mV (vs CSE, the same below) and -900 mV, pitting corrosion is observed around the matrix and inclusions; at -1000 mV, pitting corrosion occurs only in non-metallic inclusions When the polarization potential was raised to -1 200 mV, no obvious corrosion was observed on the sample surface.