Parametric Optimization, Slurry Erosion, and Characterization of 3D Printed Metallic Specimens of Steel 1.2709 and 1.4542

Abstract This study presents a comprehensive investigation of process optimization and performance evaluation of Steel 1.2709 and Steel 1.4542 made from Selective Laser Melted (SLM) method. A Central Composite Face-Centered Design (CCFD) based on Response Surface Methodology (RSM) was employed to assess the effect of laser power (200-400 W) and scanning speed (800-1200 mm/s) on ultimate tensile strength (UTS) and impact toughness. Based on regression modeling and numerical optimization, the optimal parameter combination was determined as 234.80 W laser power and 912.52 mm/s scanning speed, which yielded superior mechanical performance for both steels. However, 1.2709 steel outperformed as compared to 1.4542 steel across all conditions. Fractographic analysis via SEM revealed ductile fracture modes in Steel 1.2709, while Steel 1.4542 exhibited ductile-brittle failure with intergranular cracking. Furthermore, slurry erosion behavior was examined under varying impact angles (30°, 60° and 90°) and erodent particle sizes (100-300 µm). Steel 1.2709 exhibited reduced erosion loss (i.e., 19.6 mg) relative to Steel 1.4542 (i.e., 23.2 mg), owing to its enhanced microstructural integrity and strain accommodation capabilities. Post-erosion SEM analysis confirmed distinct wear mechanisms, majorly plastic ploughing in 1.2709 and brittle pitting in 1.4542.