OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 4 2022 Results and their discussion The studied samples’ microstructure after various heat treatment modes is shown in Figure 1. The figure shows a comparison of the obtained microphotographs of samples (left side) with microphotographs characterizing the reference image for identification from the atlas of microstructures (right side). The letter F denotes the ferritic phase; P – perlite; M – martensite. Fig. 1. The structure of the samples obtained by analysis in the SIAMS 800 software and hardware complex in comparison with micrographs from the atlas of microstructures: a – water quenching; b – tempering at 200 °С; c – tempering at 650 °С а b c One of the main indicators of the steel mechanical properties is its hardness. It has a correlation with the ultimate strength [15]. Although, according to the literature, the steel in question is not subjected to a quenching process, the properties obtained on such steel differ significantly from the original properties. The hardness value given in Table 2, obtained on the samples under study, is an average of five measurements. Ta b l e 2 Hardness of the 09Mn2Si steel samples Heat treatment HV20 Water quenching 1515.86 Tempering at 200 oС; air cooling 1761.02 Tempering at 350 oС; air cooling 1558.48 Tempering at 500 oС; air cooling 858.52 Tempering at 650 oС; air cooling 516.3
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