Simulation of structure formation in the Fe–C–Cr–Ni–Si surfacing materials

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The paper investigates the formation of equilibrium phase state in the surfacing materials 300Cr25Ni3Si3 and 500Cr40Ni40Si2BZr, obtained by electric arc surfacing that employs powder tapes PL AN-101 and PL AN-111. This makes it possible to determine the relationship between chemical composition of the tape and the structure of the formed coating. To examine the patterns of phase transformations during crystallization, we applied thermodynamic simulation using the "Thermo-Calc Software". Phase diagrams of the system Fe-Cr-Ni-Si-C were constructed and analyzed; it was established that the alloys in equilibrium belong to the hypereutectic alloys. Their crystallization starts with the formation of primary carbides М7С3 with a hexagonal lattice and ends with the eutectic transformation "Liquid ® Austenite + М7С3". The alloy 500Cr40Ni40Si2BZr at a temperature below 1,081 °C undergoes carbide transformations М7С3«М3С2. In the alloy 300Cr25Ni3Si3, austenite partially transforms into ferrite in a temperature range below 830 °C. At 600 °C, the alloys consist of the following phases: the alloy 300Cr25Ni3Si3 ‒ austenite, ferrite, and carbide М7С3; the alloy 500Cr40Ni40Si2BZr ‒ austenite and carbides М7С3 and M3C2. It was established that the molar fraction of carbides in the alloy 500Cr40Ni40Si2BZr is considerably higher than that in the alloy 300Cr25Ni3Si3 (56 mol. % and 41 mol. %, respectively). We analyzed a change in the volumetric fraction and phase chemical composition of the alloys depending on temperature. The data obtained make it possible to predict the behavior of alloys under specific operating conditions.

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