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

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.