焊接气孔对ENi620镍基焊条熔敷金属显微组织的影响

Effect of Welding Pore on Microstructure of Weld Metal of ENi620 Ni-based Electrode

针对LNG储罐用镍基焊条国产化过程中气孔缺陷对熔敷金属的元素分布与组织形貌的影响,采用金相显微镜、扫描电镜及X射线衍射设备获得气孔在熔敷金属中的形貌照片、气孔内壁的元素分布和主要物相图谱。结果表明,气孔通过改变其周围晶粒的生长方向与晶粒尺寸,从而影响熔敷金属微观组织;气孔内壁存在球状颗粒,主要由Fe、C、O及Ni等合金元素组成;气孔通过影响元素的偏聚而影响晶粒的元素组成,在气孔周围析出细小的奥氏体相晶粒。根据各表征结果,推测熔敷金属中的气孔类型最有可能为CO气孔。

In view of the influence of pore defects on the elemental distribution and microstructure of weld metal in the process of localization of nickel-based electrode for LNG storage tank,metallographic microscope,scanning electron microscope and X-ray diffraction equipment were used to obtain morphology photos of pores in weld metal,elemental distribution and main phase maps of inner wall of pores.The results show that pores affect the microstructure of weld metal by changing the growth direction and size of grains around the pores.Spherical particles exist in the inner wall of pores,which are mainly composed of Fe,C,O and Ni elements.Pores affect the chemical composition of grains by affecting the segregation of elements,and fine austenite grains precipitate around the pores.Based on all the experimental characterization,it is presumed that the pore type in weld metal is most likely CO pores.