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通过对X80管线钢进行固体渗碳模拟焊接接头区域的Fe_3C和退化珠光体组织,采用扫描Kelvin探针(SKP)、扫描振动参比电极(SVP)和局部电化学交流阻抗谱(LEIS)结合浸泡实验分析了Fe_3C和珠光体对铁素体钢表面电化学性能以及在鹰潭土壤模拟溶液中的局部腐蚀发生规律的影响.结果表明,退化珠光体组织在空气(湿度为40%,温度为22℃)中的腐蚀电位低于贝氏体铁素体,并且随着Fe3C含量的增加,腐蚀电位降低;渗碳试样在鹰潭模拟溶液中发生局部腐蚀,中心铁素体区为整个材料电偶腐蚀的阴极,退化珠光体和退化珠光体/贝氏体铁素体区为阳极,随着Fe3C含量的增加,阳极溶解电流密度增大;模拟溶液各离子含量成倍增加后,退化珠光体的阳极电流密度升高,电化学交流阻抗值降低,局部腐蚀效应增大.
X80 pipeline steel was subjected to solid carburizing to simulate the Fe_3C and degenerate pearlite in the welded joint region. The microstructures were characterized by scanning Kelvin probe (SKP), scanning vibration reference electrode (SVP) and local electrochemical impedance spectroscopy (LEIS) The effects of Fe_3C and pearlite on the electrochemical properties of ferritic steel and the local corrosion in the simulated solution from Yingtan soil were analyzed experimentally.The results showed that the degradation of pearlite in air (humidity 40%, temperature 22 ℃ ) Was lower than that of bainitic ferrite, and the corrosion potential decreased with the increase of Fe3C content. The carburized samples were locally corroded in the Yingtan simulated solution and the central ferrite region was the galvanic corrosion of the whole material Of the cathode, degenerate pearlite and degenerate pearlite / bainitic ferrite region as the anode, with the increase of Fe3C content, the anodic dissolution current density increases; the ion concentration of simulated solution doubled, the degeneration of pearlite anode The current density increases, the electrochemical AC impedance decreases, the local corrosion effect increases.