Optimization of process parameters of cold metal transfer welding-based wire arc additive manufacturing of super Duplex stainless steel using response surface methodology

Abstract

The parameter selection is essential to achieving the desired bead geometry and minimizing the various defects such as discontinuous weld beads, cracks, porosity, and waviness during the fabrication of wire arc additive manufacturing (WAAM) samples. The purpose of this study is to examine the effect of three input process parameters (current, welding speed, and gas flow rate) at three distinct levels on the properties (weld bead width, bead height, and dilution) of samples fabricated using super Duplex 2507 stainless steel through the cold metal transfer (CMT)–WAAM process using response surface methodology (RSM). To create a design of experiment involving three process parameters, a central composite design (CCD) matrix was utilized, and adequacy was checked by ANOVA analysis. The maximum values for weld bead width and bead height were 6.57 mm and 3.43 mm, respectively; the minimum dilution observed was 31.30%. The predicted optimal input parameters were 190.46 A current, 8.94 mm/s welding speed, and 15 l/min shielding gas flow rate. The results indicated that current was the most influential factor in determining the multiple responses, followed by welding speed and gas flow rate. The microstructures were characterized by optical microscopy, and results indicated that the microstructure of weld bead region consisted of ferrite and austenite. The microhardness of the CMT-based WAAM fabricated samples was also evaluated. This study holds significant potential for the fabrication of stainless-steel additive manufacturing products using a CMT-based arc welding process.