Effects of the tribo-oxide and matrix on dry sliding wear characteristics and mechanisms of a cast steel

The dry sliding wear tests were performed at the ambient temperature range of 25–400 °C on a pin-on-disc configuration for a cast steel with various tempered microstructures. The effects of the tribo-oxide and matrix on the dry sliding wear behaviors were investigated and wear mechanisms were explored. The wear behaviors and wear mechanisms of the steel were found to be closely related with the tribo-oxide and matrix. With an increase in the ambient temperature and load, the amount of tribo-oxides increased, but the subsurface matrix softened for high-hardness microstructure and workhardened for low-hardness microstructure. Tribo-oxides reduced wear on a prerequisite that matrix retained certain strength to support tribo-oxide layer, otherwise they did not provide the protection against wear. For the tempered martensite and tempered troostite, trace or a small amount of tribo-oxides would relatively reduce the wear rate of adhesive wear. A small amount of tribo-oxides formed at 200 °C totally prevented intermetallic contact, mild oxidative wear prevailed. However, as the matrix was soft (tempered sorbite) or softened at elevated-temperature, tribo-oxides could not reduce wear; the oxidative wear was beyond mild oxidative wear, even the plastic extrusion wear prevailed.