he structure and phase composition of prehardened 38CrNi3MoVN steel subjected to an electron beam treatment have been studied by the metallographic, scanning, and transmission electron microscopy. The e-beam parameters are as follows: the energy of accelerated electrons U ~ 15 keV, the beam current I ~ 60 ?, the current pulse duration t ~ 30 µs, the pulse repetition rate f ~ 1 Hz, the beam diameter in the specimen surface plane D ~ 1.6 cm, and the beam energy density ES ~ 10 J/cm2. The e-beam treatment of the material has been shown to result in a gradient structure whose characteristic feature is a considerable (tenfold) decrease in the average size of martensite crystallites and laths with attended increase in the steel surface layer hardness by a factor of 2.5−3.