Research of surface microstructure of the steel 40CrNiMo after EDM

Abstract

Abstract The aim of the work is to study the influence of modes of electrical discharge machining, on the microstructure and microhardness of the treated surface of thermally hardened steel 40CrNiMo. To fulfill the task, a sample was made of hardened steel 40CrNiMo. The sample was processed in various modes of electrical discharge machining. Microsections were made from the obtained sample. Metallographic and microdurometric analysis was carried out. The study of the microstructure showed that no clearly defined altered layer was detected in all processing modes. The study of microhardness showed that near the surface of the studied samples there is a drop in the level of microhardness. This phenomenon is caused by tempering during the surface heating during processing. The heat-affected zone does not exceed 1.2 mm, and is minimal under high-performance modes.