| CHEN Yu-da,PAN Jin-zhi,LIU Peng-tao,ZHAO Xiu-juan,REN Rui-ming.Effects of Surface Roughness on Bending Fatigue Properties of Motor Train Unit Wheel Steel[J],46(2):172-177 |
| Effects of Surface Roughness on Bending Fatigue Properties of Motor Train Unit Wheel Steel |
| Received:August 29, 2016 Revised:February 20, 2017 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2017.02.028 |
| KeyWord:wheel steel surface roughness bending fatigue stress-life curve |
| Author | Institution |
| CHEN Yu-da |
School of Materials Science and Engineering, Dalian Jiaotong University, Dalian , China |
| PAN Jin-zhi |
School of Materials Science and Engineering, Dalian Jiaotong University, Dalian , China |
| LIU Peng-tao |
School of Materials Science and Engineering, Dalian Jiaotong University, Dalian , China |
| ZHAO Xiu-juan |
School of Materials Science and Engineering, Dalian Jiaotong University, Dalian , China |
| REN Rui-ming |
School of Materials Science and Engineering, Dalian Jiaotong University, Dalian , China |
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| Abstract: |
| The work aims to provide effective guidance for predicting wheel fatigue by analyzing impact of varying degrees of surface damage on fatigue property of wheel steel. Surface residual stress distribution of varying degrees of surface damage samples was measured by using X-ray diffractometer. Fatigue test of varying degrees of surface damage samples was performed by using a bending fatigue test machine. The fracture morphology of samples were analyzed by using SEM. Surface roughness of sample Ra4.1 was about 2~3 times that of sample Ra0.7. Fatigue limit of sample Ra0.7 was 287.5 MPa, and Ra4.1 280 MPa, the former was 2.6% higher. Under the same stress, fatigue life of sample Ra0.7 was at least an order of magnitude higher than that of Ra4.1. The fatigue cracks of Ra0.7 caused by surface machining mark was about 20 μm in depth; while fatigue cracks of Ra4.1 caused by surface pit was about 100 μm in diameter and 40 microns in depth. The larger the surface roughness is, the more serious the surface damage is, and the higher surface residual stress will be. The greater the surface roughness is, the more serious the surface stress concentration is, and the greater the material fatigue property decrease will be. All samples crack due to the surface macroscopic defects of surface damage. The cracks may be present on surface of large surface roughness easily and expand inward rapidly. |
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