<p>The structure and properties of chromium-nickel austenitic steel with surface layer modified with silicon during surfacing of powder silicon carbide by a beam of relativistic electrons released into air atmosphere are studied. It is shown that the process of electron beam heating yields a structure consisting a silicon-alloyed austenitic matrix, complex chromium carbides (Cr, Fe)₇C₃ with a chiefly dendritic structure, and silicon carbides Si₅C₃ in the surface layers up to 2800 μm thick. The solid solution strengthening and the presence of the carbides promote increase in the microhardness of the modified steel layer to 10 GPa, which is four times higher than the hardness of the base metal. The heat resistance of the austenitic steel with the modified layer is twice higher than that of the base metal at 850°C.</p>