Experimental research contains the impact of changing the quenching medium, tempering temperatures and the number of tempering cycles on the tool steel D2. The purpose of this research was to determine the optimal parameters of heat treatment to achieve the desired hardness of the material with regard to some other mechanical properties of the steel.
In the experimental part, we prepared a series of samples of tool steel D2, which were quenched with two different quenching media, and then tempered several times at different temperatures. After each heat treatment step, the hardness of the samples was measured using the Rockwell C method. At the end of the heat treatment, the samples’ internal residual stress levels were measured using the X-ray diffraction method and the differences in the microstructure were analysed under an optical microscope.
We found that the optimal tempering temperature is 550 °C, as the hardness of the steel decreases during tempering at higher temperatures, and its mechanical properties will thus be resistant to changes during further use up to 550 °C.
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