Engineering Physics Annotation << Back ELECTRON-BEAM SURFACE MODIFICATION CARBON STEEL A.V. IONINA The mechanisms of hardening of the surface layers of carbon steel 45 after combined treatment, which consists in electroexplosive boron aluminizing, aluminizing steel 45 together with silicon carbide, and subsequent EPO, are revealed. A signifi cant increase in microhardness by 7 and 6 times and wear resistance by 2.5 and 1.7 times, respectively, was found. Wear resistance in dry conditions showed sliding after electroexplosive boron aluminizing and EPO by a maximum of 43 times, and with electroexplosive aluminizing with silicon carbide - by 12 times. It is shown that a multiphase structure is formed along the depth of the alloying zone of steel 45 after combined treatment, represented by martensite crystals of packet and lamellar morphology, interlayers of retained austenite, ferrite grains and subgrains, austenite cells, SiC particles of submicron sizes and nanoparticles of complex composition Al4SiC4, precipitates of particles of second phases composition AlB12, AlFe4, Fe3Si. Surface hardening is achieved due to the formation of a finely dispersed nonequilibrium structure containing hardening phases. Electron-beam action leads to leveling of the relief, healing of microcracks and improvement of functional properties. Keywords: surface hardening, electro-explosive alloying, structure, dislocation substructure, hardening mechanisms, microhardness. DOI: 10.25791/infizik.12.2022.1302 Pp. 17-27.