GRADIENT-LAYERED STRUCTURE FORMED ON THE SURFACE OF THE WHEEL STEEL DURING PLASMA QUENCHING
DOI:
https://doi.org/10.47100/herald.v1i2.84Keywords:
wheel steel, plasma quenching, transformation, gradient-layered structure, austenite, martensite, wear resistance, microhardness, mechanical properties of steel, depth of hardening.Abstract
The paper presents the mechanism and kinetics of structure formation along the cross section of the hardened zone during surface plasma quenching of wheel steel. The relevance and prospects of using plasma surface treatment of metal materials based on the treatment of solid-rolled wheels with a plasma jet are shown. In the process of such processing, the formation of the structure and properties of the material occurs in its thin surface layer up to 1-3 mm thick with the same chemical composition, structure and properties of the Central (axial) zone. When analyzing the microstructure based on a thermokinetic diagram and the distribution of microhardness, the development of a diffusive martensite transformation, which leads to the formation of needle-like martensite, is
established. The formation of a gradient-layered structure in the surface layer of plasma-hardened wheel steel has been studied, which has allowed to exclude the formation of a sharp border from martensite structures to troost-martensite and mixed plate structures. This factor, as it turned out, increases the contact fatigue strength of wheel steel and contributes to its crack resistance.
