Increasing the Wear Resistance of Engineering Parts Using Thermal Cycling Treatment

The article discusses the features of structure formation during thermal cycling treatment of hypoeutectoid structural steels 20, 40X and 65G. The process of thermal cycling treatment with heating without phase recrystallization and with complete phase recrystallization has been studied. Thermal cyclic treatment without phase recrystallization forms residual thermal stresses, causing an increase in the density of dislocations, the development of the initial stages of recrystallization. The maximum level of residual stresses is formed after 5 cycles. Thermal cyclic treatment with complete phase recrystallization leads to the development of recrystallization processes of varying intensity on the surface in the core of the steel sample. After 4 cycles, a collective recrystallization is possible on the surface with obtaining a grain size difference. In the core, the processes of polygonization and “recrystallization in place” take place. So for the 2nd cycle of TCT at 700 °C the average broadening of the X-ray line was only 8.72, for a similar process at 400 °C it was already 9.45. By the fifth cycle, at all TCT temperatures, the residual stresses and the resulting broadening of the X-ray line increase.

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