阵列参比电极法研究316不锈钢焊缝腐蚀行为

Corrosion Behaviors of 316 Stainless Steel Weldment Studied by Array Reference Electrodes

应用自行建立的阵列参比电极技术,原位测量316不锈钢焊接样品在12%FeCl3溶液中腐蚀电位分布.同时借助电化学极化曲线、交流阻抗技术和扫描Kelvin探针对316不锈钢焊缝腐蚀进行跟踪检测.结果表明,经焊接的316不锈钢样品在12%FeCl3溶液中,最初时刻焊缝区发生优先腐蚀,而在母材区保持钝化状态;随着浸泡时间延长,焊缝区电位不断负移,局部腐蚀加剧,并达到最大值;浸泡45 min,母材局部位发生电位负移,并出现腐蚀.扫描Kelvin探针(SKP)和金相观察的结果表明,焊缝有较高的腐蚀敏感性;金属焊接过程材料组织和成分的变化是导致316不锈钢焊接样品发生局部腐蚀的主要原因.

The array reference electrodes were developed to in situ measure the potential distributions of the welded 316 stainless steel.The images of potencial distribution were interpreted based on the results from metallographic analysis,polarization curve,EIS and volta potential imaging.It was indicated that the weld zone of metal suffered preferential corrosion when exposed to an agressive environment due to the distinct changes of structure and composition during the welding process.With time prolonging,the corrosion potential of the welding zone was negatively shifted to a maximum value,and then declined gradually.After 45 min immersion,the corrosion development from welding zone to the matrix was observed.The results of array reference electrodes is consistent with that of scanning Kelvin probe in which the welding zone exhibited higher corrosion susceptibility than the matrix.