Influence of steel masses and quenchants on mechanical properties of steel

Increasing demands of users for insurance of the prescribed mechanical properties and working order of machine parts require a search of the relations between the composition and microstructure and knowledge of microhardness and residual stress present, based on good knowledge of the quenching process. This paper presents results regarding cooling intensities of some oils of domestic production and of polymer water solutions. Numerous microhardness measurements on heat-treated steel specimens with different masses were made. The variation in microhardness in the axial direction differs considerably from the expected variation in microhardness after quenching in 10% polymeric water solution as well as after oil quenching. It is estimated that the differences in variations of microhardness throughout the height of the cylindrical specimen are due mainly to the circumstances in the workpiece and quenchant in the boundary layer. Numerous microhardness measurements provided important information on various masses of steel when using different quenching agents.