Mild-to-severe wear transition and transition region of oxidative wear in steels

Dry sliding tests for steels were performed in air under the test temperature at 400 °C and the loads of 50–250 N. The wear behavior and characteristics were focused on to explore their general characters in severe conditions. The wear behavior of various steels presented a common wear regular pattern; a mild-to-severe wear transition occurred with an increase of the load. Because oxidative wear prevailed, this was suggested to call the mild-to-severe wear transition of oxidative wear. More importantly, a transition region in the oxidative wear was found to exist and corresponded to the different-extent plastic deformation of the subsurface substrate. Through reviewing the past research, the mild-to-severe wear transition of oxidative wear was noticed to be a popular phenomenon in dry sliding wear of severe conditions, particularly elevated-temperature. This transition (region) with oxidative-wear characteristics was considered to the essence of wear failure in severe conditions, which was a physical and chemical process including oxidation, thermally softening and plastic deformation of worn surfaces and subsurfaces. And the wear characteristics in the transition region were revealed.