Narrow gap multi-pass laser welding with 52M/308L double wires filler addition for SA508/316L dissimilar metals

Recently, considerable effort has been directed at the development of laser welding with wire filler addition as an alternative manufacture technique for the substantial productivity gains it would offer to the nuclear pressure vessels fabrication. However, single wire filler such as 52M and 308 L addition is difficult to take into account many properties such as the strength, toughness and resistance to stress corrosion cracking at the same time. In this work we evaluate the feasibility of applying 52 M/308 L dissimilar double wires filler addition for the multipass narrow gap laser welding (NGLW) of SA508/316 L dissimilar metals. The objectives of this paper is to regulate the microstructure of the welded joint by adjusting the ratio of the 52 M/308 L double wires filler. The results showed that welded joints without crack and lack-of-fusion were acquired. An excellent comprehensive property welded joint with relative high hardness and low residual stresses is acquired when the 52 M/308 L double wires proportion was 75 %:25 %. The results also indicated that a certain proportion of 308 L stainless steel wire filler addition was conducive to reducing the microhardness of the welded joint. However, when that ratio of the 308 L wire was up to 75 %, harmful element S was obtained in the precipitation zone, which might reduce the mechanical properties of the welded joints.