Study of regularities of structural-phase transformations during thermocyclic treatment of tool steels

Abstract Movement of carbon atoms to dislocations reduces the specific volume of the martensite phase, which, in turn, affects the general level of volumetric changes that occur as a result of phase transformations during quenching. The measurements carried out on samples of steel ShX15 showed that the minimum increase in geometric dimensions is observed. Intermediate tempering and re-quenching do not change this pattern. At the same temperature, for this steel grade, the minimum degree of martensite tetragonality was recorded. This study has shown that to obtain a high level of final properties of tool steel, the most optimal is to obtain a substructure with a high level of defectiveness of the crystal structure of steel. It was found that the use of thermal cycling treatment contributes to an increase in the level of defectiveness of the crystal structure. It was also found that the use of aqueous solutions of polymers as a quenching medium makes it possible to obtain a cooling rate less than in oil quenching, which helps to reduce the level of quenching stresses.

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