磁场辅助CMT焊接X80管线钢焊缝的显微组织和力学性能

Microstructure and Mechanical Properties of X80 Pipeline Steel Welded Joint by Magnetic Field Assisted CMT Welding

研究了纵向交变磁场辅助CMT焊接X80管线钢焊缝的显微组织和力学性能。使用光学显微镜和扫描电子显微镜对焊缝的显微组织及晶粒取向进行分析,使用万能试验机和冲击试验机对焊缝的力学性能进行检测。结果表明,加入磁场后,焊缝组织由回火马氏体向针状铁素体和粒状贝氏体转变,焊缝组织细化,焊缝的抗拉强度、冲击韧性提高。由于磁场对熔池金属的搅拌作用,焊缝中粗大的柱状晶组织被打碎,作为异质形核点,促进了针状铁素体形核,细化了晶粒,提高了焊缝的力学性能。

The microstructure and mechanical properties of X80 pipeline steel welds by magnetic field-assisted cold metal transfer(CMT)welding were studied.The microstructure and grain orientation were analyzed by optical microscopy(OM)and scanning electron microscopy(SEM).The mechanical properties of the weld were tested by using universal testing machine,Vickers hardness tester and impact testing machine.The results show that after adding magnetic field,the weld microstructure transforms from tempered martensite to acicular ferrite and granular bainite,the weld structure is refined and the tensile strength and impact toughness of the weld are increased.Due to the stirring effect of the magnetic field on the molten pool metal,the coarse columnar crystal structure in the weld is broken,as heterogeneous nucleation point,it promotes the needle ferrite nucleation,and the grains are refined and the mechanical properties of the weld are improved.