| FENG Shuo,DING Tengwei,LI Na,CAI Shengyang,WANG Limei,QIAO Yang,WANG Xiangyu.Effect of Cryogenic Treatment on Bearing Steel and Grinding Surface Quality[J],54(9):248-259 |
| Effect of Cryogenic Treatment on Bearing Steel and Grinding Surface Quality |
| Received:September 10, 2024 Revised:January 23, 2025 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2025.09.021 |
| KeyWord:grinding processing residual stress cryogenic treatment microstructure carbide dislocation density |
| Author | Institution |
| FENG Shuo |
School of Mechanical Engineering, University of Jinan, Jinan , China |
| DING Tengwei |
School of Mechanical Engineering, University of Jinan, Jinan , China |
| LI Na |
School of Intelligent Manufacturing and Control Engineering, Qilu Institute of Technology, Jinan , China |
| CAI Shengyang |
Shandong UXG Bearing Manufacturing Co., Ltd., Shandong Liaocheng , China |
| WANG Limei |
School of Mechanical Engineering, University of Jinan, Jinan , China |
| QIAO Yang |
School of Mechanical Engineering, University of Jinan, Jinan , China |
| WANG Xiangyu |
School of Mechanical Engineering, University of Jinan, Jinan , China |
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| Abstract: |
| The deformation caused by the release of residual stress from the workpiece is an important factor leading to the service life reduction or even scrapping of bearings. According to the precision requirements of thin-walled bearings, a method is proposed to reduce the residual stress in bearing steel by grinding assisted by low-temperature treatment. The GCr15 bearing steel specimens in the annealed state are subject to quenching + tempering (QT), quenching + tempering + cryogenic treatment (QTC), and quenching + cryogenic treatment + tempering (QCT) in three different heat treatments, and the bearing steel after the three different treatments are selected for the grinding processing test. The hardness, microstructure, residual stress and phase composition of the materials of different treated specimens are tested with a microhardness tester, a scanning electron microscope, a residual stress tester and an X-ray diffractometer. After the specimens are treated by QTC, the diffuse distribution of carbides as well as the percentage of fine carbides increase, the dislocation density within the specimens increases, and the residual stresses increases, in which the percentage of 0.2-0.4 μm fine carbides within the specimens of QTC-12 h increases by 12.55%. After the specimens are treated by QCT, the hardness of the specimens increases slightly, the austenite content and the dislocation density within the material decrease, and the residual stress within the QCT-6 h specimens is relieved, and the residual stress decreases by 30.62%. The influence of the residual stress in the direction of grinding feed is as follows:feed rate > grinding depth > heat treatment process > wheel velocity. For the influence of the residual stress perpendicular to the grinding feed direction, it is as follows:grinding depth > feed rate > heat treatment process > wheel velocity. The QTC treatment or QCT treatment on the specimen before grinding has a certain effect on the surface residual stress, and the effect of the two types of heat treatment varies greatly under different grinding parameters. The surface compressive stress of the QTC-treated specimen increases rapidly when the depth of grinding is 0.05 mm, and the surface residual stress of the specimen is relatively reduced when the feed rate is 0.6 m/min, the depth of grinding is 0.05 mm, and the wheel line speed is 25 m/s. The residual stress on the surface of the QCT treated specimens increases and then decreases slowly when the depth of grinding increases, and the residual stress on the surface of the specimens is small and there are no obvious organizational defects when the feed rate is 0.6 m/min, the depth of grinding is 0.01 mm, and the speed of the grinding wheel line is 25 m/s. At a grinding depth of 0.07 mm and above, microcracks appear on the surface of the QTC-treated specimens after grinding, and obvious burn marks appear on the surface of the QCT-treated specimens. Cryogenic treatment before and after tempering is beneficial to the bearing steel to improve the hardness and reduce the internal residual austenite content. Tempering after cryogenic treatment can reduce the residual stress caused by cryogenic treatment and make the workpiece have better dimensional stability. Specimens subject to cryogenic treatment after tempering show a lower residual stress on the surface as the grinding depth increases, which is more conducive to the control of the residual stress after grinding. This study provides a new idea to improve the residual stress of materials after grinding processing. |
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