STRUCTURE-PHASE STATES OF HSS DEPOSITED LAYER AFTER TEMPERING AND ELECTRON BEAM TREATMENT

10.25712/ASTU.1811-1416.2025.02.010

Abstract

The structural-phase states and defect substructure of plasma surfacing with non-current flux-cored wire in the nitrogen medium of R2M9 high-speed steel on the substrate of medium-carbon steel 30HGSA in the initial state, after high-temperature tempering and electron beam treatment were analyzed using scanning and transmission electron microscopy. Electron beam processing was carried out with the following parameters: the energy of accelerated electrons is 18 keV, the energy density of the electron beam is 30 J/cm2, the pulse duration is 50 micro-seconds, the repetition frequency is 0.3 Hz, the number of pulses is 5. The formed deposited layer with a thickness of ~5 mm has a frame-type carbide structure, which is not fractured during subsequent tempering and pulsed elec-tron beams irradiation. Carbides in compositions MC, M6C, M23C6 and M7C3 are present in the initial state after sur-facing and after tempering. After electron beam treatment, the main carbide forming the frame is M6C carbide. Plasma surfacing is accompanied by the formation of martensitic structure; nanosized inclusions of the second phase, having the following compositions: MoC, Mo2C, M6C, were identified along the boundaries and in the vol-ume of martensite crystals. Their relative content is 34 wt. %. in the initial state, 33 wt. % after tempering and 19 wt. % after electron beam treatment.