Laser-arc hybrid welding of 321 stainless steel: Structure and microhardness of weld metal

Abstract

Laser-arc hybrid welding of 321 stainless steel is performed in order to reveal patterns of weld structure formation. Due to the combined influence of two heat sources during the welding process, it is possible to weld thick sheets in one pass. But when welding thick-walled structures there are difficulties due to the occurrence of defects in the depth of the weld, unstable delivery of additive material to the root of the weld. In this work, 321 stainless steel with a thickness of 10 mm was used, without edge preparation. The additive material corresponded to the chemical composition of the alloy to be welded. Great attention is paid to the uneven distribution of microhardness in the weld metal. It is shown that the microhardness decreases gradually to the root of the weld. Also, the shape of the welded joint obtained by laser-arc hybrid welding was investigated in comparison with microhardness data. An attempt was made to describe the thermal history of the laser-arc hybrid welding process on the basis of microhardness measurements inside the weld.