The mechanism of increase of the thickness of the zone of thermal effect during pulse-periodic treatment of a target by an electron beam

Based on the results of numerical simulation of temperature fields, the rea sons for the growth of the layer thickness of the zone of thermal effect in a target of 45 steel during pulse-periodic stimulation by a low-energy hig h-current electron beam in the mode of initial melting are analyzed. It is concluded that the growth of thickness of these layers is primarily caused by the spread of the beam energy density from pulse to pulse and by the pre sence of individual pulses with a higher-than-average value of energy densi ty. It is shown that the variation of the thermal properties of steel, whic h occurs during irradiation due to the carbon saturation of the surface reg ion of the target, results in the increase of the thickness of only those l ayers of the zone of thermal effect which are formed in the region of forme r melt. The dependence of the target temperature on the number of irradiati on pulses is measured and calculated numerically. It is demonstrated that t he increase of the target temperature has no noticeable effect on the growt h of the thickness of the zone of thermal effect.