Based on SEM observations and the XRD analysis, the evolution of the structure and phase composition of the plasma-surfaced 1.3355 steel is investigated in three states, namely after plasma surfacing, after high-temperature tempering, and after high-temperature tempering and electron beam processing. Plasma surfacing provides the formation of the layer with such major phases as the BCC α-Fe-based solid solution and M6C (Fe3W3C–Fe4W2C) carbides. It is found that the carbide network formed in the material structure is the main hardening phase of the plasma-surfaced layer. It is shown that plasma surfacing is accompanied by decomposition of the α-Fe-based solid solution with the generation of nanosized carbide particles in the grain volume.