A mechanism of microcrater formation in metallic material irradiated by a low-energy high-current electron beam

Experiments with stainless steel (304L grade) samples exposed to microsecond pulses of high-current low-energy (10–30 keV) electron beam have been performed to determine dependences of the morphology, average diameter, and density of irradiation-induced microcraters on the beam energy density. A mechanism is proposed, according to which the crater formation is caused by radial spreading of the melt from the site of localization of a MnS inclusion under the action of the surface tension gradient caused by overheating of the inclusion. Estimations of the dimensions of microcraters are in satisfactory agreement with experimental data.