激光冲击处理后X80焊接接头表面质量对腐蚀性能的影响

Effects of surface qualities on corrosion performances of X80 pipeline steel welded joints by laser shock processing

关键词:  激光冲击波  X80管线钢焊接接头  表面粗糙度  残余应力  残余奥氏体

Key words:  laser shock wave  welded joint of X80 pipeline steel  surface roughness  residual stress  residual austenite

摘要:

利用激光冲击波对X80管线钢焊接接头进行强化处理,用金相显微镜、光学轮廓仪分析激光冲击处理前后金相组织与表面粗糙度,并用应力测试仪测试了激光冲击处理前后残余应力和残余奥氏体的变化,分析了激光冲击波改善焊接接头表面质量的机理.结果表明,激光冲击处理后焊接接头表面晶粒细化,表面粗糙度有所提高;激光冲击处理形成了残余压应力,残余奥氏体向马氏体转化;激光冲击处理后表面粗糙度和残余奥氏体对慢拉伸性能的影响起主要作用,内积功下降3.8%;激光冲击处理后应力腐蚀敏感指数I_SCC由50.94%下降至45.10%,残余压应力和晶粒细化是提高其抗应力腐蚀的主要机制.

Abstract:

The surface of X80 steel pipeline welded joint was processed with laser shock processing (LSP),and the microstructure and roughness of welded joint before and after LSP was analyzed with metallographic microscope and optical profilometer, respectively. The changes of residual stress and residual austenite of welded joint before and after LSP were measured with stress tester,the mechanism of improving the surface qualities of welded joint by LSP was also discussed. The results show that the grain refinement of X80 pipeline steel welded joint is produced by LSP,the surface roughness has increased a little. The compressive residual stress is formed by LSP,and residual austenite is transformed into martensite. The effect of surface roughness and residual austenite by LSP on its tension performances is a main factor,its inner product power decreases 3.8%. The sensitivity index ISCC of stress corrosion of the sample by LSP decreases from 50.94% to 45.10%,the compressive residual stress and refined grain are the main mechanisms of affecting its stress corrosion resistance.