Structure Features And Wear Resistance Of Layers, Formed By Ni-Based Self-Fluxing Alloy Combined With Boron By Electron Beam, Revealed In The Air Atmosphere

Introduction. The formation of protective layers on working surfaces of machine parts comprised of chromium-nickel austenitic steels is an effective way to increase its reliability and durability. Ni-base self-fluxing alloys are widely used in order to create wear resistant coatings. The possibility of increasing the set of properties of Ni-Cr-Si-B alloys by adding reinforcing compounds to its matrix or by synthesizing reinforcing phases directly in the process of forming a protective layer is a significant interest of domestic and foreign scientists. The literature does not provide the information on the formation of protective layers on the surface of austenitic steels using cladding by relativistic electron beams of a Ni-Cr-Si-B alloy in combination with hardening additives. Aim of the current work is to increase the tribotechnical properties of the surface layers of steel workpieces via air-revealed electron beam cladding of a Ni-Cr-Si-B alloy in combination with amorphous boron taken in different weight ratios. The proportion of amorphous boron in the powder mixture is 5, 10, and 15 wt. % respectively. The structural features of the cladded layers are investigated by using the following research methods: optical metallography (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron microprobe analysis (EMPA). The properties of the surface hardened materials are determined by microhardness investigations and wear resistance during friction against fixed abrasive particles and under conditions of hydroabrasive treatment. Results and discussion. The material produced during cladding of a Ni-Cr-Si-B alloy in combination with 15 wt. % boron is characterized by the maximum microhardness (1000 HV) and wear resistance under various wear conditions. The main structural factor providing an effective increase in the operational characteristics is the formation Fe2B, (Cr, Fe)B borides. It is shown that during Ni-Cr-Si-B alloy +15 wt. % boron cladding precipitation compounds are characterized by phase heterogeneity. The inner part of the two-phase complex particles is CrB2 around which (Fe, Cr)2B is released.