Study of Strength Properties of a Nitrided Gear Wheel

Abstract

The article investigates the linear static characteristics of a stainless steel gear wheel after thermochemical treatment (nitriding). As a result, the product hardness and wear resistance increase. The experiment has shown that the optimum temperature for the formation of a nitrided case with a hardness of 11 740–12 003 MPa for corrosion-resistant refractory steel 12Kh18N9T is 570–590°C with a nitriding time of 48 h. However, overly high hardness of the nitrided case increases the brittleness of the gear wheel; therefore, deep surface treatment may be required when grinding or polishing. It is shown that, after nitriding, the steel under study has a homogeneous structure with clearly pronounced transition layers; the average thickness of the nitrided case is 60–90 μm. The stress-strain state (SSS) of the product before and after nitriding, which determines the internal stresses and deformation of the wheel tooth, shows that the static characteristics are approximately equal. However, a nitrided wheel has a higher hardness, greater safety margin and less tendency to deform at high loads.