Experimental investigation of microstructure and mechanical properties of 904L super austenitic stainless steel fabricated by CMT-WAAM

Cold metal transfer wire arc additive manufacturing has emerged as a viable additive manufacturing technique for fabricating large scale components from corrosion-resistant alloys with minimal distortion. In this study, 904L super austenitic stainless steel was deposited using cold metal transfer wire arc additive manufacturing and its quantitative microstructural evolution and mechanical behavior were systematically compared with the base metal. The as-deposited wall exhibited a fully austenitic microstructure with 99.7% γ-phase and negligible secondary phases. Electron backscatter diffraction (EBSD) analysis revealed grain coarsening in the deposit, with the average grain size increasing from 24.27 ± 15.91 μm in the base metal to 39.25 ± 101.84 μm in the wire arc additive manufacturing wall. A pronounced crystallographic texture was also observed with the texture intensity increasing from 2.53 to 17.07 attributable to directional solidification and epitaxial grain growth during layer-wise deposition. The horizontal specimens attained an ultimate tensile strength of 641 ± 23 MPa, a yield strength of 302 ± 14 MPa, and an elongation of 42.4 ± 2%. Microhardness was the highest in the bottom region of the deposit at 202.41 ± 11 HV, compared to 167.2 ± 4 HV for the base metal. The findings show that cold metal transfer wire arc additive manufacturing can produce 904L components with controlled microstructures and superior mechanical performance compared to conventional base metal.