In recent years, the attention of researches in the field of physical materials science is focused on the study of facing of composite coatings hardened with the particles of carbides, borides and other high solid phases. The principal factor determining the service properties of the faced layers is phase composition of coating materials. In order to make substantiated choice of coating material corresponding to the conditions of their extreme service, high loads and abrasive wear it is necessary to carry out thorough studies of their properties and structure. Structure-phase states and tribological properties of coating faced on Hardox 450 martensite low carbon steel with Fe – C – Cr – Nb – W powder wire and modified by subsequent electron beam processing were studied in the research using methods of modern materials science. The regime of electron beam processing is the following: parameters of electron beam at the first stage – energy density of electron beam in pulse ES = 30 J/cm2, duration of pulses τ = 200 μs, number of pulses N = 20; at the second stage – ES = 30 J/cm2, τ = 50 μs, N = 1. The regimes of irradiation were chosen based on calculation results of temperature field being formed in surface layer of material in one pulse regime irradiation. It is shown that electron beam processing of ~5 mm thick faced layer results in formation of ~20 μm thick modified surface layer with α-Fe and NbC carbide major phases and negligible quantity of Fe3C and Me6C (Fe3W3C) carbides. The principle difference of the surface layer modified by electron beam processing from the unmodified volume of facing is morphology and dimensions inclusions of the second phases. In the facing modified layer inclusions have smaller dimensions and are located in form of thin interlayers along the grain boundaries. In the unmodified facing, basic morphological type of inclusions is particles of faceted shape located chaotically in grain volume. After electron beam processing wear resistance of the faced layer increases in more than 70 times in relation to wear resistance of Hardox 450 steel and friction coefficient decreases significantly (in ~3 times).
ASJC Scopus subject areas
- Materials Science (miscellaneous)
- Metals and Alloys