Nikulchenko I. Influence of non-metallic inclusions on structure formation and strengthening of surface layer with increased mechanical properties under laser treatment

The peculiarities of melting of nonmetallic inclusions and interphase inclusion-matrix boundaries were established, as well as the formation of "satellite" particles under laser action. The peculiarities of the structure of inclusions after high-speed solidification are shown. The peculiarities of the formation of zones of contact interaction in the steel matrix and in the surface layers of nonmetallic inclusions under laser treatment were studied. It was established the peculiarities of transformation of the inclusion-matrix boundaries is associated with heterogenization of their structure. New factors that determine the influence of nonmetallic inclusions on the strengthening of steels under laser action are established. It was shown that laser treatment allows to reduce their average size and contamination of steel. The effect of deformation modes and laser treatment on the initiation of cracks near inclusions during deformation was established. The effect of the structure of the microcomposite zones of saturation of the steel matrix on the spreading of cracks from inclusions, related to their inhibition, was investigated. The possibility of local strengthening of the railway wheels scrap zone was shown, when it is possible to obtain a bainitic structure of a laser-hardened layer. Key words: laser treatment, steel, nonmetallic inclusions, interface nonmetallic inclusion - steel matrix boundaries, melting, dissolution, gradient and microcomposite formations, cracks, plastic deformation.