STRUCTURE AND PROPERTIES OF HIGH SPEED MOLYBDENUM STEEL SURFACING

10.25712/ASTU.1811-1416.2025.03.002

Abstract

Using methods of modern physical materials science (optical, scanning electron microscopy, micro-hardness measurement), the structural-phase states and properties of plasma surfacing with current-carrying flux-cored wire in a nitrogen environment of high-speed molybdenum steel type M10 on a substrate of medium-carbon steel 30 KhGSA were studied. The formed layer is ~10 mm thick. It has a polycrystalline dendritic structure. Map-ping methods revealed the localization of molybdenum, chromium, aluminum, and silicon in the structure of the sur-facing. Using the point-by-point X-ray spectral microanalysis method, it was shown that carbon, nitrogen and oxy-gen are present in areas of the material enriched with aluminum atoms. This leads to the formation of oxycarboni-trides of submicron size, randomly located. The relative content of all surfacing elements, excluding carbon, oxygen and manganese, decreases as one approaches the surfacing-substrate contact zone. The constructed microhardness profile revealed its significant dependence on the distance to the substrate. The surface layer with a thickness of ~1 mm has the maximum microhardness (average value 5.60 GPa). As one moves away from the surface, the micro-hardness decreases sharply, approaching the microhardness of the substrate. The average microhardness of the sur-facing is ~1.8 times higher than the microhardness of 30KhGSA steel (substrate).