Investigation of the boost correction in determining structures –property correlation of cold metal transfer arc welded 18/8 stainless steel joints

Abstract

Cold metal transfer arc welding (CMTAW) is a low-heat-input and low-spatter process. In the current work, the influence of Boost correction (0, 2, and 4) on the welded joints of 18/8 stainless steel was studied. The micrographs revealed the formation of δ-ferrite (lathy and skeletal) and austenite phase in the weld zone. Depending on the influence of boost correction (BC) and its associated heat input, lathy ferrite formation varied. However, the heat-affected zone (HAZ) was found to be negligible, and all the welded joints exhibited a defect-free structure. The volumetric fraction, grain size, and texture of austenite and ferrite formed in the fusion zone were estimated and analyzed using electron backscattered diffraction (EBSD). The presence of metal carbides at the boundaries and intragranular region of grains was observed under a scanning electron microscope (SEM). The BC:2 showed higher hardness of 198 ± 2 HV, tensile strength 640 ± 10 Mpa, and lower elongation 45.7 ± 6% than BC = 0,4. The formation of a higher volume fraction of δ-ferrite at the fusion zone, finer grains, and weak texture resulted in higher strength and hardness of BC: 2 as compared to BC: 0 and BC:4.