Influence of dispersed particles of tungsten carbide on the microstructure of 12Kh18N10T steel obtained by centrifugal casting

Abstract

The development of new technologies in various industries, such as fast neuron reactors, require a new level of operational properties from steels and raise the issues of resistance to neutron radiation, radiation swelling, embrittlement and creep, and the level of residual activation. The principal way to increase these properties is to adjust the chemical composition, and rearrange the crystal structure of the metal. The authors propose to achieve this by introducing finely dispersed particles into the melt and controlled by them to “reinforce” the crystal lattice, grinding the metal structure. During the work, using the FactSage software package, thermodynamic modeling of the interaction of dispersed particles with a 18Х18Н10T steel melt was carried out, showing that the particles will interact with the metal melt, which can lead to their complete dissociation, and at the next stage of crystallization, regardless of the degree of dissolution of tungsten carbide, the formation of carbide phases based on titanium carbide with an FSS structure, as well as a carbide phase based on chromium carbide with the formula M23C3, will become. According to the simulation parameters, experiments were conducted, experimental blanks with different contents of the introduced tungsten carbide were obtained, and heat treatment was carried out. The study of microstructures showed that the introduced particles of tungsten carbide completely dissociate when interacting with a metal melt and contribute to an increase in ferrite in the microstructure of the workpiece. Studies of microhardness confi rmed the significant effect of the introduced carbide on the properties of the material: the maximum values of microhardness are achieved at a high concentration of refractory particles in the areas of their maximum concentration (outer edge of the workpieces). Carrying out heat treatment reduces microhardness, while aligning the gradient of properties with the volume of castings. This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation within the framework of the federal target program under Agreement No. 075-15-2019-1711 (internal number 05.608.21.0276) dated December 04, 2019 (unique project identifier RFMEFI60819X0276).