In this paper the development of hardness and microstructure in the near-surface region during wear loading is investigated. The investigations were carried out by using nanoindentation and SEM on the cross-sections of samples subjected to wear. Steels with approx. 1 - 1,2 wt.% C, 1.5 wt.% Si, approx. 2- 4 wt.% Mn and approx. 0.5 wt.% Cr were used as sample material.

The depth profiles of hardness and microstructure is presented and discussed in view of the wear resistance of those steels. It is shown that a transformed layer forms directly below the surface during wear loading. This layer is about 2 µm thick and exhibits hardness values up to 13 GPa. The microstructure below this transformed layer is characterized by the appearance of sliding bands. This slip-band-region extends approximately to a depth of 10 µm. Within this region the hardness drops to approx. 9 GPa. At about 100 µm the hardness decreases further, to about 5 GPa. The correlation between hardness and microstructure is further discussed in the paper.