Tribology of as-received Armox 500T steel under variable dry sliding conditions

This study investigates the dry sliding tribological behavior of as-received Armox 500T steel using a pin-on-disc tribometer across three rotational speeds (350, 400, and 450 RPM) and four applied loads (20, 30, 90, and 120 N). Microstructural characterization confirmed a fine lath martensitic structure with retained austenite, yielding an average Vickers microhardness of 528.64 HV. Volume loss, specific wear rate, coefficient of friction, and surface roughness were evaluated as tribological responses. Rotational speed drove a mild-to-severe wear regime transition and dominated specific wear rate (∼88% ANOVA contribution), while applied load exclusively governed coefficient of friction (COF) (∼99.8%). An inverse relationship between surface roughness and specific wear rate at higher speeds was attributed to thermally induced surface flattening and mechanically mixed layer formation. The Time × Applied Load interaction was the largest contributor to volume loss, confirming the time-dependent nature of material removal. These findings provide practical guidance for avoiding critical speed–load combinations in sliding applications.