OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 1 2023 Fig. 4. EDS of 40-Cr steel after CDS by the formation of chromium carbides diffusing from the process medium, in this case, from a fusible liquid metal solution. Also, despite the fact that during CDA, the diffusion of the chromium alloying element depends on the elemental composition of the steels being coated, the chromium content on the surface has approximately the same percentage. The chromium concentration on the surface of St3 steel is 66.8 %; on the surface of steel 40-Cr – 64.22 %; on the surface of steel 20-Cr13 – 62.54 %; on the surface of steel 40-Cr13 – 63.18 %; steel 12-Cr18-Ni10-Ti – 64.77 %. This is due to approximately the same carbon concentration in the surface layers of the steels being coated due to the fact that it was subjected to preliminary carburizing under the same conditions. This also explains the reduced chromium content on the surface of the coatings. There is no effect of the composition of steel after CDA on the total thickness of the diffusion-alloyed coating. The total thickness of the coatings formed on all the steels lies in the range from 17 to 17.5 μm. Conclusions 1. It is established that the coatings formed by the process of DSLMMS differ significantly from the coatings obtained by CDA. Under the same chromizing modes, multilayer coatings are formed in the DSLMMS and CDA processes, at least the base layer and transition layers, however, the elemental-phase composition, the concentration distribution of alloying elements in the coatings being formed are different. 2. CDA leaded to the formation of coatings of a much greater thickness than DSLMMS. There is no influence of the composition of the steel being coated on the overall thickness of the diffusion-alloyed coating. 3. The chromium concentration in the surface layers of the coating after DSLMMS is quite large for diffusion coatings, and lies, depending on the composition of the steel being coated, in the range from 96.9 to 91.1 % Cr. After CDA, the Cr concentration on the surface of the coating is much less and ranges from 66.8 to 62.54 %. After the CDA, under the same conditions, the elemental composition and concentration distribution of elements in the formed coatings are determined both by the elemental composition of the alloyed steel and by a significant increase in the carbon concentration in the surface layers of the steels being coated from 2.4 % carbon obtained on steel 40-Cr13 to 0.7 % carbon obtained on austenitic steel 12-Cr18-Ni10-Ti.
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