Structural-Phase Statesand Properties of Plasma Surfacing With High-Speed Steel in a Nitrogen Environment

Using the methods of modern physical materials science, studies of the structural-phase states and properties of plasma surfacing from high-speed steel R18Yu in a protective alloying environment of nitrogen were carried out. The main element of the structure of the deposited word is grains, the size of which is 7.0 –22.5 microns. It has been shown that plasma surfacing with a non-current-carrying flux-cored wire leads to the formation of a layer, the main phases of which are α-Fe and carbides of composition M6C (M = Fe, W), which form a frame mesh represented by two morphologically different types in the form extended layers and areas with a eutectoid-type structure. The inclusion of the carbide phase does not contain a dislocation sub-structure and is characterized by the presence of flexural extinction contours, which indicates elastic stresses of the surfacing material. The scalar density of chaotically distributed dislocations in α-Fe grains is 2.2∙1010cm–2,and in the network dislocation substructure 1.2∙1011cm–2. Using transmission electron microscopy, particles of vanadium carbide of composition V4C3with needle-like morphology were identified in the volume of grains. The crystal lattice parameter (a = 2.888 Å), the size of coherent scattering regions (44 nm) and the carbon concentration in the α-Fe solid solution (0.286 wt.%) were assessed. The microhardness of the deposited layer is 4.7 GPa, the wear parameter is 8.9∙10–6mm3/N∙m, the thorn coefficient is 0.7.