Investigation of high-temperature wear behavior of TiN and TiAlN PVD-coated low alloy steel AISI 4140

Purpose AISI 4140 is a versatile, low alloy steel often used in various applications in mechanical systems and manufacturing processes. To mention a few in processes such as friction stir welding tooling and in engine components, temperatures above 700°C coupled with wear. Despite its versatility, it is still susceptible to wear and corrosion. A common method to address this shortcoming is physical vapor deposition (PVD) coating. This study aims to experimentally investigate the wear performance of AISI 4140 PVD coated with titanium nitride (TiN) and titanium aluminum nitride (TiAlN) at room and elevated temperatures. Design/methodology/approach Two sets of three samples were prepared. Where one sample was uncoated AISI 4140, TiN and TiAlN PVD coated, one set was tested at room temperature and the other set at 780°C for comparison purposes. The average coating thicknesses were measured, and the adhesion properties were assessed using a scratch test. Their tribological wear scars were further characterized using scanning electron microscope (SEM) energy-dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), Raman and confocal microscopy, and the results were furnished in the paper. Findings With the scratch test, the first critical load (Lc) on the TiAlN coating was 15% higher than that of the TiN coating. At room temperature, TiN had the highest coefficient at 0.61, while TiAlN was 0.39. After 1,500 s, samples showed run-in and stability. At elevated temperatures, TiAlN started with the highest friction but stabilized later than TiN and uncoated samples, which stabilized after 200 s due to titanium oxide formation. This was due to the formation of an oxidation layer caused by the thermal environment. Hence, the opposite is observed at room temperature. The findings were supported by the Raman, XRD, SEM EDS and areal topography analysis. Originality/value The results presented in the study are valuable to design engineers and researchers anticipating wear in high temperature applications. Therefore, with these results, reasonable, informed decisions can be made about specific design requirements. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2024-0354/