Surface hardening of steels by high-energy electron beams of microsecond duration

The regularities of the surface hardening and the peculiarities of the transformations in a carbon steel (0.7 % C) quenched from melt under the action of an electron beam of electron energy 160–170 keV, pulse duration 20–200 µs. and power density 10⁶−10⁷ W/cm² have been studied based on heat calculations, X-ray crystal analysis and transmission electron microscopy. It has been found that maximum hardening is achieved for a pulse duration of about 40 µs. The nonmonotonic character of this dependence is accounted for by the fact that the pulse duration strongly affects the phase composition and morphology of fast-quenched steel.