Morphology, properties and stress-strain state of carburized gear made of steel 12KhN3A after high-frequency currents quenching

Abstract

The results of the study of the effect of cementation with subsequent induction quenching by high-frequency currents on the physical properties of a gear made of 12HN3A steel are presented, the influence of technological factors (temperature and time) on the cementation layer is studied. The study was carried out using a well-known pasty carbonatesoot carburetor and in a pasty carburetor with composition optimization through the synthesis of a di-ammonium salt of 2-monoethanolamine and citric acid, in terms of carbon saturation activity of steel not inferior to melts of cyanide salts. The structure and chemical composition of 12HN3A steel before and after cementation were studied. In the course of the work, the following mode of chemical-thermal treatment of 12HN3A steel was used: cementation due to exposure to highfrequency currents temperature T = 960 °C, medium — air; induction hardening due to exposure to high-frequency currents temperature T = 860 °C, medium — aqueous solution, tempering low temperature T = 190 °C, medium — aqueous a solution that provides an increase in the margin coefficient for fatigue strength to 86.1 MPa and yield strength to 820 MPa while maintaining a sufficient level of plastic properties. The stress-strain state of a gear wheel made of 12HN3A steel is estimated before and after cementation of its working surfaces with subsequent induction hardening by high-frequency currents.