STUDY ON DISSIMILAR-MATERIAL WELDING WITH VANADIUM AND AUSTENITIC STAINLESS STEEL

The hardness distribution and the effect of post welding heat treatment (PWHT) at 600 degrees C and 1000 degrees C for 1 h and aging heat treatment at 600 degrees C for 1000 h in the dissimilar-material electron beam weld (EBW) joint with pure-V and SUS316L, austenitic stainless steel were investigated. The electron beam was positioned just on the butt joint (EB00), shifted by 0.2 mm (EB02) and 0.4 mm (EB04) on the pure-V side. The EBW joint was distinguished into the base metal of V (V-BM) weld metal (WM), interlayer at the edge of the WM of SUS316L side (IL) and base metal of SUS316L (SUS316L-BM). The IL was observed only in the EB02 and EB04 joints. The formation of macro-pore was observed in the EB04 joint. Much higher hardness was observed at the WM and IL of the as-welded EB00 and EB02 joints than the other regions of them. The hardness change in the WM was relatively small due to the PWHT at 600 degrees C up to 1 h, whereas significant increment was observed due to the PWHT at 1000 degrees C for 1 h regardless of the EB position. The hardness of the IL after the PWHT at 600 degrees C was almost twice higher than that of the as-welded one, which showed slightly further increment at 1000 degrees C. Rapid increment of the hardness due to the aging at 600 degrees C for 1-10 h and slightly further increment of it due to the aging for 100-500 h occurred in the WM of the EB00 joint.