Process optimization and mechanical characterization of GMAW-based WAAM fabricated 80N1 HSLA steel

The current work involves inclusive examination of process parameter optimization and their effect on bead geometry, microstructure, and mechanical characterizations of 80N1 high-strength low-alloy (HSLA) steel processes through gas metal arc welding (GMAW)-based wire arc additive manufacturing (WAAM). The influence of WAAM variables, wire feed speed, voltage, and travel speed were investigated on bead height, and bead width responses using the Box–Behnken design (BBD) approach. A multi-objective optimization was carried out to obtain optimized set of WAAM variables. A multi-walled component was successfully fabricated at the optimized conditions and subjected to detailed microstructural and mechanical characterization. The microstructure revealed a predominantly dendritic morphology across the top, middle, and bottom regions, with comparable morphological features observed along the build direction. However, the optical micrographs do not permit definitive identification of phase constituents, thermal history, or metallurgical bonding. Tensile testing showed improved mechanical performance compared to the base 80N1 HSLA wire, with average values of 541 ± 16.12 MPa (YS), 636.67 ± 15.56 MPa (UTS), and 29.93 ± 1.75% elongation. Microhardness exhibited a gradual variation from 222.61 ± 7.11 HV (bottom) to 251.46 ± 8.65 HV (top), which was associated with the differences in the observed microstructural morphology along the build direction. The results demonstrate that the optimized GMAW-based WAAM parameters produced a multi-layer structure with comparatively consistent mechanical properties across the examined regions. The study establishes a robust correlation among the process parameters, bead morphology, microstructure, and mechanical performance, confirming the potential of WAAM for producing high-performance HSLA steel components for industrial applications.