Study on Tribological Characteristics of High Entropy High-Speed Steels in Conditions of Dry Friction on Structural Steel

The connection between the entropy of HSS grades and their frictional properties and elastic strength characteristics of surface layers at the microlevel was experimentally confirmed. It was established that the best friction characteristics are connected with a high level of entropy, which apparently can be explained by the peculiarities of forming the third body (build-up layer) and its composition. The growth process of the third body for high entropy HSS flows with a greater speed than its destruction, and the obtained thickness of the third body contributes to the alienation of friction surfaces reducing the strength of adhesive joints and the coefficient of friction. These properties become apparent under conditions when the value of thermomechanical activating effects in the friction zone is of an adequate level. It was established that build-up layers on specimens of high entropy HSS have a greater stability due to their high hardness and low elasticity of surface layers. The authors proposed the process of build-up layer formation during friction for HSS having various entropy levels characterized in the first approximation by the two quantitative indicators: the maximum possible value of build-up layer thickness under specified conditions and the relative rate of build-up layer formation versus destruction. It was assumed that the calculation of entropy values as structurally sensitive characteristics of the tool materials may be used for a priori prediction of the tribological properties of existing and newly developed grades of HSS.