Study on the magnetic property response mechanism of Cr4Mo4v bearing steel under grinding burn

To address the challenge of detecting and quantifying grinding burns in bearing steel, this work reveals the regulation mechanism of burn-induced microstructural evolution on the macroscopic magnetic properties of Cr4Mo4V steel. Specimens with graded burn severities were prepared by tuning grinding parameters, and systematically characterized via X-ray diffraction (XRD), electron backscatter diffraction (EBSD), magnetic force microscopy (MFM) and vibrating sample magnetometry (VSM). The results show that with increasing burn severity, the deformed grain fraction, dislocation density, internal stress and <111> hard-magnetic texture in the surface layer rise continuously. Magnetic domains evolve from lamellar structures to fine disordered maze domains with strengthened domain wall pinning. Macroscopically, the material presents notable magnetic hardening: saturation magnetization and remanence decrease, while coercivity increases monotonically, forming a clear quantitative mapping with burn severity. This study clarifies the microscopic mechanism of magnetization variation induced by grinding burns, and provides essential theoretical and experimental support for magnetic non-destructive testing (MNDT) of high-end bearing grinding quality.