Influence of the energy electron beam exposure regimes on the structure and mechanical properties of composite coatings

A surface density of the introduced energy is important parameter of the nonvacuum electron-beam cladding, which depends on the beam current and the sample travel velocity. The paper presents the results of a study of heat input under electron beam exposure on the structure and properties of the obtained composite coatings. Surfacing modes are considered, in which the beam current was 25 and 40 mA, and the samples velocity varied within 0.5-2.0 cm/s. Based on the studies, it was revealed that with increasing specific power of the electron beam, the coating thickness, dendrite grain size and microhardness increase, and the volume fraction of the eutectic decreases. It has been shown that with low heat input an austenitic-martensitic structure is formed, the arrangement of carbides is observed in the eutectic and in the martensite needles. In the case of large heat input, an austenitic structure with a eutectic carbide network is formed. The martensitic structure is formed only along the “coating - substrate” interface as a result of intense heat removal deep into the substrate material.

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