| XI Yan-jun,LI Xian-zhe,DONG Shu,WU Yong-le.Effect of Wear on Oxidation Behavior of U71Mn at High Temperature[J],50(5):289-294 |
| Effect of Wear on Oxidation Behavior of U71Mn at High Temperature |
| Received:May 17, 2020 Revised:July 23, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2021.05.032 |
| KeyWord:U71Mn high-speed rail high temperature oxidation wear oxide film |
| Author | Institution |
| XI Yan-jun |
Zhongyuan University of Technology, Zhengzhou , China |
| LI Xian-zhe |
Zhongyuan University of Technology, Zhengzhou , China |
| DONG Shu |
Zhongyuan University of Technology, Zhengzhou , China |
| WU Yong-le |
Zhongyuan University of Technology, Zhengzhou , China |
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| Abstract: |
| The high temperature oxidation behavior of U71Mn rail material after wear was studied, and the influence mechanism of high temperature and wear on rail surface damage was discussed. The wear test of materials was carried out with a wear tester, and the oxidation tests were carried out in a heating furnace. The interface of materials was characterized by SEM with energy spectrum, and the phases of oxides were analyzed by XRD. The effect of wear on the surface oxidation properties of U71Mn rail material at high temperature was investigated. The results showed that the amount of wear increases with the increase of load. The weight of the material without wear was obviously increased compared with that of the worn material at 800 ℃ and 900 ℃ for 5 hours. This is because there were scratch cracks on the surface of the material after wear. Oxygen in the air rapidly was adsorbed at the crack tip, diffused into the matrix at the crack tip, and formed oxides, thus reducing the atomic bond energy at the crack front, causing a large area of material surface falling off seriously. This shows that the scratch caused by wheel-rail friction has a great effect on the high-temperature properties of rail materials. The oxide film on the surface of unworn U71Mn was mainly Fe2O3 at 900 ℃ for 5 hours. The oxide film on the surface of material after 500 N wear contained FeO and Fe3O4, while the oxide film on the surface of material after 1000 N wear contained Fe2O3 and Fe3O4 at 900 ℃. The macro-defects on the surface of the material caused by scratch was the oxidation active region, and stable Fe3O4 was formed in a very short time, but the oxidation film grows quickly and unsteadily on the scratch, and part of Fe3O4 falls off, then the exposed part of the substrate was oxidized again to form FeO. The high temperature oxidation resistance of unworn U71Mn rail material is obviously better than that of worn material. Wear can accelerate the material damage at high temperature, and has a certain direction. The scratch of wheel-rail friction seriously affects the phase structure and adhesion of oxide film at high temperature, and thus affects the service life of rail. |
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