Investigation of Microstructure, Crystallographic texture, and improvement of mechanical (Wear, Hardness) properties of Nb modified 312 LSi stainless steel (with addition of 2%Nb) manufactured Via Wire Arc Additive Manufacturing (WAAM)[

Wire Arc Additive Manufacturing (WAAM) has emerged as a cost-effective technique for producing large-scale metallic components with high deposition rates and reduced material waste. However, WAAM-fabricated stainless steels often exhibit microstructural heterogeneity and defects that can limit their mechanical and tribological performance. This study investigates the effect of niobium (Nb) addition (2 wt.%) on the microstructure, crystallographic texture, and mechanical properties of 312LSi stainless steel fabricated via WAAM.

Cubic samples were deposited under three build orientations (0°, 67°, and 90°) with interlayer times of 2 and 5 minutes to evaluate process–structure–property relationships. Detailed microstructural characterization was performed using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) to analyze grain morphology, phase distribution, and crystallographic texture along the build direction.

Mechanical and tribological properties were assessed through hardness measurements and dry sliding wear tests using a pin-on-disk tribometer. The results demonstrate that build orientation significantly influences tribological behavior. The coefficient of friction (COF) ranged from 0.57 to 0.64 for the 0° orientation, while lower values (0.55–0.58) were observed for the 67° orientation, indicating improved wear performance. The addition of Nb contributed to microstructural refinement, enhanced phase stability, and improved resistance to wear.

The findings highlight the combined influence of alloy modification and processing parameters on tailoring the performance of WAAM-fabricated stainless steel. This work demonstrates that Nb addition is an effective approach to enhance microstructural characteristics and tribological performance of 312LSi stainless steel, offering potential for improved reliability in industrial applications.

Keywords: WAAM, 312LSi stainless steel, niobium, EBSD, microstructure, wear, tribology