EBSD Analysis of 316L Stainless Steel Weldment on Fusion Reactor Vacuum Vessel

The nonuniformity of microstructure and properties of welded joints of thick plate are abroad attention by people in the field of nuclear industry manufacturing. In this paper, through-thickness microstructure of electron beam welded 50 mm 316L stainless steel was investigated by the electron backscatter diffraction (EBSD) technique, including the texture evolution, grain size, orientation difference angle distribution, and Taylor factor distribution of fusion zone (FZ), heat affected zone (HAZ) and base metal (BM) in welded joint. The microstructure of the 316L stainless steel was austenite matrix with dispersed delta-ferrite. The FZ was mainly composed of columnar dendrites. The texture of the austenite columnar crystals in FZ with < 001 > fiber texture was paralleled to RD. The grains at the bottom of the weld were finer, but the kernel average misorientation (KAM) value and microhardness were higher. There has been an increase in the proportion of the substructure grains, but a reduction in the Taylor factor of the FZ after welding.