Surface Microstructure Refinement and Mechanical Properties of GCr15 Steels Improved During Ultrasonic Surface Rolling Processing

Abstract

In this paper, ultrasonic surface rolling processing (USRP) was used to strengthen GCr15-bearing steel. A finite element three-dimensional model of USRP was established to analyze the residual compressive stress and equivalent plastic strain distribution on the bearing steel surface. The microstructure, hardness, surface roughness, and corrosion resistance before and after USRP treatment were characterized by SEM, EBSD, X-ray diffraction (XRD), and electrochemical techniques. Results indicated that USRP treatment can significantly improve the material's surface microstructure and residual compressive stress distribution and obtain a plastic strain layer of about 60μm. After USRP treatment, the Kernel Average Misorientation (KAM) increased, and the dislocation activity was more intensive, resulting in aggregation near grain boundaries, and the percentage of LAGBs increased to 38.8%. Under the combined effect of surface grain refinement, residual compressive stress, and high glossy surface, the self-corrosion current density is reduced by two orders of magnitude, and the corrosion resistance is significantly improved. This investigation suggests a solution to the bearing failure problem and has implications for understanding the deformation mechanism of ultrasonic surface rolling processing.

Effect of Rare Earth Y on Microstructure and Mechanical Properties of High-Carbon Chromium Bearing Steel

“…Besides, high-purity bearing steel is developed [18,19]. The process of low alkaline slag refining combined with vacuum carbon deoxidation can achieve TiN inclusion control and improve the cleanliness of GCr15 bearing steel [20], and methods such as ultrasonic shot peening [21][22][23] and ultrasonic rolling [24] are used to form gradient nanostructured surface layers on bearing steel, which can effectively improve the surface hardness and wear resistance of the steel, and also refine the lath martensite to obtain better mechanical properties. Studies have also been carried out on oxides, sulphides and other non-metallic inclusions in bearing steel [25], as these inclusions can act as stress sources leading to cleavage cracking and significantly affect mechanical properties [26].…”