Determination of Mechanical Characteristics Plasma Hardened Wheel Steel

Abstract

A technique for measuring the mechanical properties of plasma-hardened wheel steel with nanoindentation is applied. The purpose of the work is to demonstrate and substantiate the serious differences between the mechanical properties and behavior of materials in nano-volumes from those obtained in traditional macroscopic tests. The features of measuring mechanical properties – hardness, Young’s modulus, elastic recovery – affecting the wear resistance of the surface layers of the material are given. Measurement of the physic mechanical properties of the material makes it possible to evaluate and select the optimal technology for surface modification by surface plasma hardening. It is noticed that the objectivity of determining the hardness, elastic modulus, elastic recovery and flow stress depends on the parameters of the measuring equipment used and strict adherence to the requirements for the imprint depth depending on the thickness of the hardened layer. The studies carried out on wheel steel samples from the rim and from the ridge of a railway wheel subjected to surface plasma hardening under the same conditions. The HV and H of the wheel rim are greater than the corresponding values of the flange, and the young modulus of the wheel flange, on the contrary, is greater for the flange.