Relations between oxidative wear and Cr content of steels

► Dry sliding wear mechanism and behavior depend on the role of tribo-oxides, which closely related with the chromium content of steels. ► Trace tribo-oxides reduced wear to some extent in adhesive wear. ► A small amount of tribo-oxides reached about 10 μm on contacting asperities and lead to mild oxidative wear. ► Cr-strengthened adhesion power of tribo-oxides and matrix result in high elevated-temperature wear resistance. Dry sliding wear tests at 25–400 °C were performed for 45, 4Cr5MoSiV1 and 3Cr13 steels; the relations between oxidative wear and Cr content of steels were explored. The low and medium-Cr steels had a substantially lower wear rate and increasing tendency than the high-Cr steel at 25–200 °C, but the contrary case occurred at 400 °C. With an increase of ambient temperature, the wear rate of the low and medium-Cr steels first decreased, then increased and reached the lowest value at 200 °C, while the wear rate of the high-Cr steel decreased monotonously with the lowest value at 400 °C. At 25 °C, trace tribo-oxides reduced wear to some extent in adhesive-dominated wear for the low and medium-Cr steels. At 200 °C, a small amount of tribo-oxides formed and reached a thickness of 10 μm on contacting asperities in the low and medium-Cr steels, thus oxidative mild wear prevailed. At 400 °C, a great amount of tribo-oxides appeared in the low and medium-Cr steels; unexpectedly, the high-Cr steel had more tribo-oxides than the low or medium-Cr steels in some cases. Its high wear resistance may be attributed to Cr-strengthened adhesion power of tribo-oxides and matrix.