Thermal stresses computation under high–current pulsed radiation of AISI M2 tool steel

Abstract

Surface modification of metallic materials and alloys with concentrated energy flows (powerful electron beams and ion plasma flow, laser beams) has been widely used in various fields of manufacturing. The aim of physical and mechanical properties modification is to improve the performance of the critical parts fabricated from modified materials. The mentioned energy impacts give rise to radiation, thermal and mechanical effects causing the changes in morphology, microstructure, elemental and phase composition of the surface layers, which in turn may lead to hardness, wear corrosion resistance and red hardness increasing of modified materials. However, as experimental investigations are shown, in some cases irradiation promotes the crystal defects’ occurrence and often non-uniform heating leads to the cracks’ formation in the surface layers. Thus, selection of incident electrons energy, its current density and pulse duration, taking into account the thermal stress state, is an actual problem of modern radiation technologies. This paper provides a numerical solution of differential equations in partial derivatives for the temperature fields’ computation as well as radial and axial thermal stresses distribution in R6M5 (AISI M2) high-speed steel exposed to medium-energy (up to 400 keV) high–current (up to 1 kA/cm2) pulsed (up to 1 μs) electron beam radiation. The obtained results can be useful in the optimal modes selection of tool steels and products at surface radiation treatment and evaluation of their service life.