Investigating the Tribological Performance of Laser Powder Bed Fusion-Manufactured Maraging Steel through Advanced Post-Processing Techniques

Laser Powder Bed Fusion (LPBF) facilitates the production of high-strength maraging steel components with intricate geometries; however, inherent surface roughness (∼6.125 μm) and suboptimal tribological performance restrict their application in wear-critical contexts. This study introduces an innovative approach that synergistically combines sandblasting and vibratory polishing to enhance surface integrity and wear behavior. Post-processing resulted in a 54% reduction in surface roughness (Ra = 2.809 μm) and a 4.1% increase in microhardness (481 HV). Tribological evaluations under dry, machine oil (MO), and soybean oil (SO) lubrication demonstrated that vibratory polishing decreased wear by 76.5% (263.02 × 10−9 mm3/Nm) and friction by 62.6% (μ = 0.247) under dry sliding conditions. MO lubrication on polished surfaces achieved near-hydrodynamic conditions, resulting in ultra-low wear (4.87 × 10−9 mm3/Nm) and friction (μ = 0.036). Notably, soybean oil, a sustainable bio-lubricant, exhibited performance comparable to MO (wear factor: 4.17 × 10−9 mm3/Nm), underscoring its potential for eco-tribological systems. FE-SEM analysis confirmed a transition from severe abrasive wear (as-built) to mild adhesive wear (post-processed), directly correlating surface topography with lubrication regime dominance. This research establishes vibratory polishing as a pivotal enabler for hydrodynamic lubrication in LPBF components, thereby unlocking their potential in aerospace, automotive, and precision tooling industries where wear resistance is critical for operational longevity.