| HUANG Shu-lin,YANG Yi,YANG Gang,LAN Qiao.Study on forming mechanism of penetrating cracks in Cr12MoV Guide roller[J],45(3):141-145,157 |
| Study on forming mechanism of penetrating cracks in Cr12MoV Guide roller |
| Received:December 24, 2015 Revised:March 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.03.023 |
| KeyWord:Through cracks Cr12MoV Guide roller Failure mechanism Elements segregation Numerical simulation |
| Author | Institution |
| HUANG Shu-lin |
School of Manufacturing Science and Engineering, Sichuan University, Chengdu , China |
| YANG Yi |
School of Manufacturing Science and Engineering, Sichuan University, Chengdu , China |
| YANG Gang |
School of Manufacturing Science and Engineering, Sichuan University, Chengdu , China |
| LAN Qiao |
School of Manufacturing Science and Engineering, Sichuan University, Chengdu , China |
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| Abstract: |
| Objective To analysis the reason of through cracks germination and Extended of guide roller. Methods By adopting the scanning electron microscope and energy spectrum to analyze the microscopic images and chemical composition of cracks origin and propagation area of through cracks，using a combination of the X-ray diffract meter and Vickers hardness tester to research the types and hardness of the internal carbides, and using numerical simulation to analyze the stress condition during crack propagation, the crack origin causes and propagation mechanism of the through cracks of the Cr12MoV guide roller are analyzed. Results Research shows that elements segregation is the main reason for the through cracks initiation of the Cr12MoV guide roller. As the the two elements in near surface, oxygen and chromium, are significantly higher than the crack propagation region, the guide roller can be easily separated under the action of internal stress, which forms the cracks in the near surface, and becomes cracks origin. The eutectic carbide of high hardness is the main reason for the crack propagation in Cr12MoV guide roller, the eutectic carbide is mainly (Fe, Cr)7C3 type of blocky-shaped particle, the hardness is 1327 HV, which produces quantities of micro-cracks around. Those micro-cracks are interconnected, form a mesh, divide the body, and then form the through cracks under the action of external force. Extended finite element method (XFEM) is carried out on the simulation of through cracks and the analysis of crack propagation stress. The results find out that stress of the crack-tip is the maximum, the stress curve is a sharp decrease at first, then a parabolic and reaches the vertex of parabolic when the radial thickness of guide roller has just reached their maximum. The stress of the top and bottom surface of guide roller is minimal. Conclusion The results show that the alloy elements and eutectic carbides in the guide roller have a great influence on the crack initiation and propagation, and the crack propagation stress field is directly related to the initial crack position and the size of the guide roller. |
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