Surface enhancement of SS304 for high-temperature wear resistance using laser cladded Mo-alloyed stellite 6 coatings

Abstract

Severe wear often limits the high-temperature durability of SS304 components, necessitating the development of surface-engineered solutions. In this investigation, Mo-reinforced Stellite 6 claddings were developed using Laser Directed Energy Deposition (L-DED) to provide enhanced surface protection. Claddings with (3, 6, and 9 wt%) Mo reinforcement enhanced hardness by 2.9, 3.1, and 3.3 times, respectively, compared to the SS304 substrate. This improvement is attributed to Mo-induced solid solution strengthening and the formation of hard intermetallic phases. Dry sliding wear tests were conducted at RT and 600 °C under (10 and 20 N) loads. Wear characterisation of the clads was performed using OM, XRD, FE-SEM, EDX, and Raman spectroscopy. At RT, claddings primarily exhibited abrasive wear with minor plastic deformation. However, at 600 °C, the wear mechanism evolved into a combination of severe adhesive, oxidative, abrasive, and plastic deformation modes, with oxidative wear governing the tribological behavior. Stellite 6 with 9 wt% Mo clads exhibited better tribological performance than the other two variants, owing to the development of oxide glaze layers of Cr<inf>2</inf>O<inf>3</inf>, NiO, CoO<inf>2</inf>, and Co<inf>3</inf>O<inf>4</inf>. Enhanced performance of the claddings is attributed to solid solution strengthening, Cr-rich carbide formation, increased dislocation density, and the L-DED technology enabling refined microstructure and strong metallurgical bonding. These findings highlight the potential for further advancements in Mo-reinforced Stellite 6 L-DED claddings for high-temperature wear applications. © 2025 Elsevier B.V.