OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 2 2022 a b Fig. 6. XRD-pattern of the steel surface after aluminizing: a – St3; b – 3Cr2W8V a b Fig. 7. Distribution of boron and aluminum over the layer thickness on the steels after boriding (a) and aluminizing (b) respectively Figure 6, a shows the XRD pattern after the aluminizing of St3 steel, where Al5Fe2, Na3AlF6 and Al2O3 phases were established on the surface, while Al5Fe2, Na3AlF6 and Al2O3 were identifi ed on the surface of 3Cr2W8V steel. The EDS analysis determined B and Al in the diffusion layer and transition zones. Figures 7, a and 7, b show B and Al distribution over the both steels, respectively. As it is seen on the graphs, boriding under the same conditions resulted in a slightly higher boron content (by 1–2 %) in the diffusion layer on St3 steel compared to the alloy steel. Boron content is inversely proportional to the layer thickness on both steels (Fig. 7, a). A similar picture is observed during aluminizing of the studied samples. The aluminum content was higher by 2–7 % on St3 steel compared to the alloy steel depending on the layer thickness (Fig. 7, b). It was established that the aluminum content was 3–5 % higher in the local extrema than in other areas of the layer on 3Cr2W8V steel. Conclusion Based on the study, it was found that at a process temperature of 900 °C and a holding time of 2 hours after boriding, iron borides are formed on the surface of both steels. At the same time, both FeB and Fe2B iron borides were revealed by XRD on St3 steel and a single Fe2B phase was found on 3Cr2W8V steel.
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