Influence of microstructure on tribologically mixed layers

The purpose of this study is to determine the influence of microstructure on the formation and mechanical stability of tribologically mixed layers acting as a wear reduction factor. To this purpose, AISI 420 steel specimens of different initial microstructure were subjected to annealing, quenching and tempering to 673 K and to quenching and tempering to 943 K under pure sliding conditions. The wear level for each case was evaluated on the basis of the applied load levels and in relation to the morphological features of the underlying surface affected by wear. Also locally stressed field gradients were identified by means of microhardness profiles, which were then correlated with measurements of the resulting plastic subsurface deformations on the basis of the distance to the tribolayer. On the basis of the results, the conditions of formation and mechanical stability, the relations between the mechanical properties of the initial microstructure and the needed level of stress due to the resulting plastic deformation for the tribological layer to act as factor of wear rate reduction were assessed and are herein discussed