Enhanced Wear and Oxidation Resistance of AISI 316L Stainless Steel via Slurry and Hot-Dip Aluminizing Assisted by Rapid Induction Heating

This study investigates the wear and high-temperature oxidation behavior of AISI 316L stainless steel (SS) subjected to two distinct aluminizing processes, hot-dip aluminizing (HDA) and slurry aluminizing (SA), both followed by rapid induction heating. The objective was to assess the efficiency of short-time induction heating as a diffusion treatment and to compare the resulting structural and functional properties of the coatings. Microstructural characterization was carried out by using SEM, XRD, and EBSD, while mechanical and tribological properties were evaluated by nanoindentation and wear testing. The HDA coating exhibited a uniform outer morphology, whereas the SA coating developed a lamellar structure due to localized thermal gradients during induction heating. Despite these morphological differences, both coatings consisted of Fe₂Al₅, FeAl, and α-Fe (Al) phases. The SA coating demonstrated a higher surface hardness (13.2 GPa vs 10.8 GPa for HDA) and a lower coefficient of friction (0.40 vs 0.52), resulting in a markedly lower wear rate (3.2 × 10⁻⁵ mm³/N·m vs 6.5 × 10⁻⁵ mm³/N·m). Isothermal oxidation at 1000 °C for 24 and 96 h revealed that both coatings transformed toward a protective α-Fe (Al) matrix with a continuous Al₂O₃ scale. However, the coating thickness increased more significantly in SA samples from 35 to 400 μm after 96 h compared to 230 μm for HDA, indicating superior Al diffusion kinetics in the SA process. Overall, the SA process combined with rapid induction heating exhibited superior wear resistance compared to the HDA route, whereas the HDA process combined with the same thermal treatment demonstrated enhanced oxidation resistance relative to the SA.