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This paper investigates surface state after turning of the high tempered bearing steel 100Cr6 with a hardness of 40 HRC. White layer (WL) thickness and its microhardness, as well as surface roughness, are investigated as a function of tool flank wear <i>VB</i> as well as cutting speed <i>v_c</i>. The mechanical and thermal load of the machined surface were analysed in order to provide a deeper insight into their superimposing contribution. Cutting energy expressed in terms of cutting force was analyses as that consumed for chip formation <i>F</i><i>_γ</i> and consumed in the flank wear land <i>F</i><i>_α</i>. It was found that the mechanical energy expressed in terms of the shear components of the <i>F</i><i>_α</i> grows with <i>VB</i>, converts to the heat and strongly affects the thickness of the re-hardened layer. Furthermore, the superimposing contribution of the heat generation and its duration in the <i>VB</i> region should also be taken into account. It was also found that the influence of <i>VB</i> predominates over the variable cutting speed.