Effect of GMAW-Spray transfer mode on the weld microstructure of an AISI 445 stainless steel.

The current research study analyzes the influence of short circuit (GMAW-SC) and spray (GMAW-Spray) transfer mode on the microstructure of a 445 ferritic stainless steel. The amount of δ-ferrite in the fusion zone (FZ) was determinant according to the transfer mode in the GMAW welding process. An increase of the heat input (HI) by spray transfer allows to obtain a decrease of δ-ferrite. In contrast, the short-circuit transfer mode shows an increase of 30%. Additionally, the ferritic-austenitic system studied exhibits microstructural differences in the distribution and morphology of the microconstituents depending on the transfer mode employed. The diffusive phenomena of Cr, Ni and Fe are similar regardless of the transfer mode employed. Finally, the short-circuit transfer mode produced a favorable microstructural condition with reduced HI and a homogeneous distribution of δ-ferrite in the weld bead avoiding zones of excessive grain growth in the FZ compromising the integrity of the joint.