碳钢中夹杂物诱发点蚀的规律和特性研究

Law and feature of pitting caused by inclusion in carbon steel

选用5种低碳钢,通过浸泡试验、显微腐蚀试验和极化试验,考察了碳钢在3%NaCl(质量分数,下同)溶液中夹杂物诱发点蚀的规律和特点.结果表明:样品刚浸入溶液时其最初电位高于点蚀电位,钢中一些夹杂物活化,先诱发点蚀;局部活化使钢样的电位迅速下降,当降至点蚀电位之下,未发生点蚀或未充分诱发点蚀的夹杂物受到保护,不再活化;在阳极极化试验中,当钢样的电位极化到点蚀电位或点蚀电位以上,钢中的夹杂物几乎都会活化而诱发点蚀.

Five mild steels are selected, and the pitting initiation features of steels in 3% NaCl solution are studied by means of the immersion test, micro-corrosion test, and polarization test. The results indicate that the initial potential of specimens immersed into the solution is higher than their pitting potential (E_(b)), therefore some inclusions becomeactive and initiate pitting firstly. The potential of steels drops rapidly because of the activation of local areas on the surface of specimen. When the potential of steels is lower than the pitting potential, the inclusions which don′t initiate pitting or initiate pitting deficiently are protected and don't initiate pitting anymore. In the polarization test, almost all inclusions can be active and initiate pitting when the potential of steels is equal to or higher than the pitting potential.