Pulsed multi-stage electron beam processing as a method for modifying details made of hypereutectic silumin

Abstract

Hypereutectic silumin is a lightweight, corrosion-resistant, inexpensive alloy with a low coefficient of thermal expansion. This material is a promising material for the production of parts for the mechanical engineering and aerospace industries. The primary silicon crystals present in the structure reduce plasticity and make it impossible to use this alloy without additional alloying with expensive additives. The paper proposes a method for modifying the surface layer of hypereutectic silumin using a pulsed electron beam of submillisecond duration (SOLO, ISE SB RAS) in a single vacuum cycle with multiple treatments with a stepwise decrease in the energy density of the electron beam according to the scheme (50+30+15+10) J/cm2 (0.3 s-1, 150 μs, 3 imp., 0.02 Pa). The use of the stepwise processing mode allows, by gradually reducing the volume of the melt bath, to significantly (by 4.5 times, relative to the samples processed in the mode of 50 J/cm2, 0.3 s-1, 150 μs, 3 imp., 0.02 Pa) reduce the level of roughness (Ra) of the irradiated surface of the sample with a modified layer thickness of up to 160 μm. The friction coefficient of step-modified samples decreased by 13%, the wear parameter – by 4.4 times relative to silumin in the initial state. The use of the proposed modification mode will increase the service life of products made of hypereutectic silumin.