Effect of High Magnetic Field in Combination with High-Temperature Tempering on Microstructures and Mechanical Properties of GCr15 Bearing Steel

Abstract

The microstructures and mechanical properties of GCr15 bearing steel after high-temperature tempering with and without a 5 T high magnetic field (HMF) were investigated. It was found that the application of the HMF at the stage of high-temperature tempering slowed down the growth of the tempered sorbite (TS) structures, increased the density of the carbides, and reduced the carbide size and the volume fraction. XRD diffraction patterns showed that the HMF resulted in a higher dislocation density. Hardness testing indicated that the HMF led to an increase in the Vickers hardness in the tempered sample. It is inferred that the change in carbide size stems from the reduction in nucleation barrier in the HMF and the increase in dislocation density originates from the interaction between dislocations and carbides. Additionally, the decrease in diffusivity in the HMF also contributes to the reduction in the size of TS structures and the refinement of carbides. This work demonstrates that high-temperature tempering with an HMF can slow down the growth of TS microstructures in GCr15 bearing steel, control the carbide size, and improve Vickers hardness, which provides a new heat treatment method to regulate the microstructure and properties of GCr15 bearing steel.