Q345R钢焊缝区大气腐蚀行为研究

Study on Atmospheric Corrosion Behavior of Q345R Steel Weld Zone

研究了储罐钢Q345R钢焊缝区的大气腐蚀特征,并通过极化曲线和交流阻抗技术对比分析了热影响区、焊缝和母材的腐蚀行为,结合扫描电子显微镜、激光拉曼光谱仪对样品表面腐蚀微观结构和组成进行表征。研究结果揭示:母材的腐蚀敏感性最大,焊缝区较热影响区相比更耐蚀。腐蚀倾向与显微组织存在一定关系,焊缝区的显微组织为粒状贝氏体与针状铁素体,因该区域组织细化明显降低该区域的腐蚀敏感性,同时因焊接工艺使焊缝处几乎成为无孔区,母材处存在的微孔隙会导致母材具有更高的腐蚀速率。

The atmospheric corrosion characteristics of the weld zone of storage tank steel Q345R are studied,and the corrosion behaviors of the heat affected zone,weld and base metal are analyzed by polarization curve and AC impedance technique.The surface corrosion microstructure and compositions of the samples are characterized by scanning electron microscope and laser Raman spectrometer.The results show that the base metal has the greatest corrosion susceptibility,and the weld zone is more resistant to corrosion than the heat-affected zone.There is some relationship between the corrosion tendency and the microstructure.The microstructure of the weld zone consists of granular bainite and acicular ferrite,and the refinement of the microstructure of this zone can obviously reduce its corrosion susceptibility.The welding process makes the weld almost a non-porous area;therefore,the base metal with micropores has a higher corrosion rate.