Experimental investigations and parametric effects on depositions of super duplex stainless steel in wire arc additive manufacturing

Identification of suitable processing conditions is essential for successful fabrication of engineering components of any material by wire arc additive manufacturing (WAAM). Objectives of this article are to determine optimal process parameters for deposition of super duplex stainless steel (SDSS) ER2594 in gas metal arc welding (GMAW)-based WAAM using response surface methodology (RSM) and characterisation of the deposited materials. The developed RSM-based models of deposition geometry in terms of bead width and bead height, and deposition rate based on experimental data showed higher values of width, height and deposition rate for increasing voltage and wire feed speed due to higher heat input onto the tip of wire and decreasing torch travel speed and gas flow rate. Results of tensile tests of the deposited SDSS exhibited increase of mechanical properties like yield strength, ultimate tensile strength and elongation by 28.8%, 14.3% and 84%, respectively, compared to that of the cast SDSS material. Microstructural characterisations of the deposited SDSS wall using SEM exhibited a typically higher ratio of austenite to ferrite phases (77:23) with oriented columnar dendritic structure compared to that of the base material (50:50). Pre-heating of the substrate could enhance the deposited bead size with higher width due to higher energy available for melting and spreading of the beads.