Microstructure transformations and improving wear resistance of austenitic stainless steel additively fabricated by arc-based DED process

Abstract

In this study, austenitic stainless steel (ASS) was additively fabricated by an arc-based direct energy deposition (DED) technique. Macrostructure, microstructure, mechanical characteristics at different spatial orientations (0°, 90°, and 45°), and wear characteristics were evaluated at the deposited structure top, middle, and bottom regions. Results show that austenite (γ) and delta-ferrite (δ) phases make up most of the microstructure of additively fabricated SS316LSi steel. Within γ matrix, δ phase is dispersed both (within and along) grain boundaries, exhibiting a fine vermicular morphology. The bottom, middle, and top regions of WAAM deposited ASS exhibit similar values to those of wrought SS316L in the tensile and impact test findings. Notably, a drop in hardness values is observed as build height increases. During SEM examinations of fractured surfaces from tensile specimen, closed dimples were observed, indicating good ductility of as-built structure. Wear test findings show signs of mild oxidation and usual adhesive wear. By depositing a mechanically mixed composite layer, an increase in the oxidation percentage was discovered to facilitate healing of worn surfaces. The findings of this study will help in design, production and renovation of products/components that are prone to wear. WAAM-deposited ASS has remarkable strength and ability to withstand impacts; it can be used in the production of armour plates for defence applications, mainly military vehicles and aircraft.