Heat Treatment for Property Enhancement of Wire Arc Additive Manufactured Stainless Steel

The influence of the different heat inputs and post-deposited heat treatment on the metallurgical and mechanical properties of the GMAW-based WAAM SS316L was investigated. Epitaxial columnar grain growth was observed along the build direction for all three heat inputs. The fine and coarse vermicular δ-ferrite structures were observed in the bottom and middle regions, respectively. The reticular δ-ferrite morphology was observed in the top region due to the absence of remelting or reheating. The presence of δ-ferrite and σ-phases increases with increasing heat input. The higher volume fraction of δ-ferrite and σ-phases results in an increase in anisotropy in metallurgical and mechanical properties. The post-deposition heat treatment at 1050°C for 15 min dissolves the σ-phases and decreases the δ-ferrite volume fraction from 9.35 % to 2.15 % for the lower heat input wall. The complete elimination of σ-phases leads to a decrease in Y.S., UTS, and microhardness values.