The microstructure and corrosion behavior of friction stir (FS) welded API X-60 pipeline steel were investigated. Three FS welds were successfully fabricated under various welding conditions using a tungsten carbide-base tool. It was found that the microstructure and corrosion performance of the welds were strongly affected by welding parameters. A thermal history study of the welds showed that all stir zones heated up to the temperature of the ferrite–austenite region. Electron backscatter diffraction (EBSD) characterizations revealed that a significant grain refinement in the stir zones was accompanied by the formation of low angle grain boundaries. The kernel average misorientation analyses showed that the amount of residual strain and dislocation density were increased after welding. The corrosion assessments using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements showed that the welds exhibited superior corrosion resistance than that of the base metal. There results were confirmed according to the immersion tests.

研究了搅拌摩擦焊（API）API X-60管线钢的组织和腐蚀行为。使用碳化钨基工具在不同的焊接条件下成功地制造了3个FS焊缝。结果发现，焊接参数对焊缝的组织和腐蚀性能影响很大。焊缝的热历史研究表明，所有搅拌区都加热到铁素体-奥氏体区域的温度。电子背散射衍射（EBSD）表征表明，搅拌区的晶粒细化伴随着低角度晶界的形成。核平均取向错误分析表明，焊接后残余应变的量和位错密度都增加了。使用电位动力学极化和电化学阻抗谱（EIS）测量进行的腐蚀评估表明，焊缝比基础金属具有更好的耐腐蚀性。根据浸没测试证实了结果。