Study on electron beam weld joints between pure vanadium and SUS316L stainless steel

The mechanical and metallographical properties of the electron beam weld joints between pure vanadium (V) and SUS316L austenitic stainless steel and the effect of post-welding heat treatment (PWHT) at 873 and 1273 K for 1 h on these properties were investigated. The electron beam was shifted by 0.2 mm (EB02S), 0.4 mm (EB04S), and 0.6 mm (EB06S) on the SUS316L side. No significant defects (e.g., pores, macro-cracks, or micro-cracks) were observed in the as-welded EB02S and EB04S joints, whereas a non-welded region was formed in the as-welded EB06S joint. Much higher hardness was observed in the weld metal (WM) of the as-welded EB02S and EB04S joints than in the base metals (BMs), which might be attributed to solution hardening. A significant increment in the hardness of the WM of EB02S joint occurred due to the PWHT at 873 and 1273 K, which might be attributed to solution hardening and formation of Ni₂V₃ and NiV₃ precipitates. Almost no change in the hardness due to the PWHT at 873 and 1273 K occurred in the WM of the EB04S joint. The interlayer was formed at the edge of the WM of the V side only in the post-welding heat-treated EB04S joint. The interlayer showed much higher hardness than the BMs and WM, which might be attributable to solution hardening, formation of σ phase of the Fe-V system, and formation of Ni₂V₃ and NiV₃ precipitates.