焊接方法对X90管线钢焊接接头性能的影响

目前,关于焊接方法对X90管线钢焊接接头组织性能的影响相关报道较少。采用手工电弧焊(SMAW)、熔化极气体保护焊(GMAW)、埋弧焊(SAW)3种焊接方法对X90管线钢进行对接焊。利用金相显微镜(OM)、扫描电镜(SEM)及能谱仪(EDS)对焊接接头及冲击断口进行显微组织及成分分析,分析了焊接方法对X90管线钢焊接接头组织性能的影响规律。结果表明:焊缝区组织主要为粒状贝氏体和针状铁素体;SMAW粗晶区组织主要为多边形铁素体、粒状贝氏体及M/A组织,GMAW和SAW粗晶区组织主要为粗大的铁素体、粒状贝氏体及板条贝氏体;3种焊接接头硬度分布趋势一致,盖面层硬度最高;SMAW、GMAW和SAW焊接接头抗拉强度依次为714,771,790 MPa,断后伸长率依次为23.3%,22.9%,20.0%;SAW与GMAW熔合线处20℃冲击吸收功比SMAW高约40 J,断裂机制为微孔聚集型,在韧窝底部有金属碳化物粒子析出。

Effect of Welding Methods on Properties of Welded Joint of X90 Pipeline Steel

x90 pipeline steel was butt welded by three methods:manual electric arc welding (SMAW),gas metal arc welding (GMAW) and submerged-arc welding (SAW).The microstructure and composition of the welding joint and fracture were examined by optical microscope (OM),scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS),and the influence rule of SMAW,GMAW and SAW on microstructure and properties of X90 pipeline steel was analyzed.Results showed that the microstructure of the weld zone was mainly granular bainite and acicular ferrite.The coarse grain heat affected zone (CGHAZ) of SMAW was polygonal ferrite,granular bainite and M/A,while those of GMAW and SAW were mainly coarse ferrite,granular bainite and lath bainite.All three kinds of welded joint had similar hardness distribution tendency,and the hardness of cover surface layer was always the highest.The tensile strengths of SMAW,GMAW and SAW welding joints were 714,771,790 M Pa,respectively.The percentage elongations after fracture were 23.3 ％,22.9 ％,20.0 ％,respectively.Impact absorption powers at 20 ℃ of SAW and GMAW on the fusion line were higher than that of the SMAW by about 40 J.Besides,the fracture mechanism was micro pore aggregation type,and metal carbide particles were precipitated in the bottom of the dimple.