Assessment of the effect of the steels structure dispersion on its magnetic and mechanical properties

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 4 2021 Fig. 3. Histogram of the percentage distribution of grains by points for micro-sections of heat-treated samples made of 15KhSND steel by grain size [20] where f i – is the proportion of grains with a certain severity, %; f max – is the proportion of grains that oc- cupy the maximum part on the cross-section, %; Z i – is the grain severity; Z max – is the grain severity that occupies the maximum part on the cross-section. Results and discussion The values of the uneven-grained factor obtained in the study [20] are shown in Figure 4. It can be noted that the highest value in the magnitude of the uneven-grained factor is observed in a sample tempered at temperature of 200 o C. This is due to the beginning of the process of violation of the coherence of the lattice of martensite and cementite [22–24], as a result of the beginning of carbon separation processes [24, 25]. During these processes, a region with a carbon-depleted phase with low hardness is formed in the material, as well as a new phase in the form of ferrite and cementite. The fragmentation of the martensite phase oc- curs, which leads to an increase in the number of grains with a higher severity. Fig. 4. Change in the value of the factor of different grain size F z for samples made of 15KhSND steel with different heat treatment [20]