Investigation of high-temperature wear behaviour of Mo-alloyed SS316 laser claddings deposited by LDED for heat exchanger tubes

Abstract

Pronounced surface degradation due to high-temperature wear remains a significant challenge for SS304-based components, particularly in heat exchanger tubes that endure harsh loading conditions. SS316 and Mo-reinforced composite claddings (10 and 20 wt%) were developed on SS304 substrate through laser direct energy deposition (LDED) to enhance high-temperature wear resistance. This research evaluated the high-temperature wear performance of these composite claddings using ball-on-flat tribological testing under applied loads of 10 and 20 N at 400°C. Microstructural evolution, wear mechanisms, and oxide formation were comprehensively analyzed using FE-SEM, XRD, EDS, and Raman spectroscopy, while surface topography was assessed with 3D non-contact profilometry. Compared to SS316 clads, the SS316 with 10 wt% Mo clads exhibited increased hardness and facilitated the formation of stable oxide films, leading to a shift from severe adhesive wear to a more stable oxidative wear mechanism. The development of protective glaze layers, including Fe<inf>2</inf>O<inf>3</inf>, Fe<inf>3</inf>O<inf>4</inf>, and MoO<inf>3</inf> in the SS316+20 wt% Mo composite clads resulted in reduced plastic deformation, yielding smoother wear scars and lower wear rates. The SS316 + 20 wt% Mo composite clads demonstrated enhanced wear resistance, achieving a 60 % reduction in wear rate compared to SS316 clads and a 29 % improvement over the SS316+10 wt% Mo composite clads. This study highlights the potential of Mo-reinforced SS316 claddings deposited via LDED for high-temperature industrial applications. © 2025 The Authors