激光冲击对X70管线钢焊缝盐雾腐蚀的影响

利用激光冲击波对X70管线钢焊缝进行了表面改性处理,通过人工气氛盐雾腐蚀试验考察了激光冲击处理前后焊缝的盐雾腐蚀行为.用扫描电镜、能谱分析仪和X射线衍射技术分析了盐雾腐蚀后焊缝表面形貌、腐蚀物的化学元素和物相组成,讨论了激光冲击处理对其腐蚀机理的影响.结果表明,原始状态的X70管线钢焊缝存在残余拉应力,易与腐蚀介质Cl-发生应力腐蚀开裂,且与晶界腐蚀共同作用发生剥落腐蚀;激光冲击处理使得试样内部晶粒细化,表层产生强化层,有利于提高焊缝抗盐雾腐蚀性能.

Effects of laser shock wave on salt spray corrosion of X70 pipeline steel welded lines

The surface of X70 pipeline steel welded line was treated by laser shock wave, and the corrosion performances before and after laser shock processing were analyzed by salt spray corrosion test in artificial atmosphere.The surface morphologies, chemical elements and phase constituent were observed with SEM(scanning electron microscope), EDS(energy dispersive spectrometer) and XRD(X-ray diffraction), respectively, and the effects of laser shock processing on the corrosion mechanism were discussed.The results show that tensile residual stress exists in the surface of X70 pipeline steel welded lines in primitive state, which improves stress corrosion crack with the interaction of corrosive medium Cl^-.Spelling corrosion occurs with the interaction of boundary corrosion.The grain refinements are produced in the welded lines by laser shock processing, and the strengthened layer is formed on the surface, which improves corrosion resistance of the welded lines.