Qiu Jiajia, Zhang Min, Tan Zhunli, Gao Guhui, Bai Bingzhe
School of Mechanical, Electronic and Control Engineering, Materials Science and Engineering Research Center, Beijing Jiaotong University, Beijing 100044, China.
Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Materials (Basel). 2019 Sep 20;12(19):3061. doi: 10.3390/ma12193061.
A bainite/martensite multiphase rail is treated by the controlled-cooling process with different finish-cooling temperatures. The simulated temperature-time curves of the position of 5 mm and 15 mm below the rail tread (P5 and P15) express different trends. P5 has greater impact toughness and lower tensile strength than P15. Microstructural characterization was carried out by conducting scanning electron microscopy, X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy. The greater tensile strength is due to the dispersed ε-carbides hindering the movement of dislocations. The greater impact toughness is attributed to the filmy retained austenite and the smaller effective grain with high-angle boundary. Finite element modeling (FEM) and microstructural characterization reasonably explain the changes of mechanical properties. The present work provides experimental and theoretical guidance for the development of rail with excellent mechanical properties.
贝氏体/马氏体多相钢轨通过不同终冷温度的控制冷却工艺进行处理。钢轨踏面以下5mm和15mm位置（P5和P15）的模拟温度-时间曲线呈现出不同的趋势。P5比P15具有更高的冲击韧性和更低的抗拉强度。通过扫描电子显微镜、X射线衍射、电子背散射衍射和透射电子显微镜进行微观结构表征。较高的抗拉强度归因于弥散分布的ε-碳化物阻碍位错运动。较高的冲击韧性归因于薄膜状残余奥氏体和具有高角度边界的较小有效晶粒。有限元建模（FEM）和微观结构表征合理地解释了力学性能的变化。本工作为开发具有优异力学性能的钢轨提供了实验和理论指导。
