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采用电化学极化与金相显微镜原位观察相结合的方法,对Q235钢在3%NaCl溶液中腐蚀的初始行为进行了研究。借助原子力显微镜对初始腐蚀的试样观察分析,发现试样在-900 mV(vs SCE)就出现了点蚀,点蚀优先在晶界附近的铁素体上生成。蚀坑长大后,优先沿轧制方向发展,而形成腐蚀沟槽。钢中夹杂没有发生活性溶解,导电性夹杂物作为阴极仅对腐蚀过程起促进作用。
The initial behavior of Q235 steel corrosion in 3% NaCl solution was studied by the combination of electrochemical polarization and metallographic microscope in situ observation. Observed by atomic force microscopy on the specimens of the initial corrosion, it was found that the specimens developed pitting corrosion at -900 mV (vs SCE), with pitting preferentially occurring on the ferrite near the grain boundaries. After the pit grows up, it preferentially develops along the rolling direction and forms the corrosion groove. The inclusions in the steel did not occur active dissolution, conductive inclusions as cathodes only promote the corrosion process.