| Rails and turnouts are basic parts in railway system. As the railway industry wordwide is introducing heavier axle loads and higher vehicle speeds, it has become essential to explore the possibility of developing new grades of high strength rail material and frog steel. Since 1980, railroad researchers and manufacturers have begun to study bainitic steel for track, and developed some new bainitic steels for frog and rails.In this paper, we studied the mechanical properties and microstructure of two bainitic steels which we designed for switch and crossing. All steels were made in an vacuum induction furnace to produce about 30kg ingots. After being forged with air cooling, specimens were made for all experiments. The results of tensile and Charpy U notch (CUN) impacts tests showed that the two bainitic steels have higher strength and CUN toughness than that of current premium rail steels. The UTS varys between 1280 and 1337MPa, and the good value for the elongation at fracture of 16% is obtained. The value of CUN toughness is 20J/cm2 and 46J/cm2 respectively. The fracture toughness (K1c) of the second bainitic steel at -20 0C is also noteworthy, which up to 42MPa m1~2. The transmission electron micrograph showed that microstructures of the two bainitic steels consist of ferrite laths and hin films?type of retained austenite. High dislocation density in ferrtie laths were revealed also. Meanwhile, the bainitic basic units were distinguished in ferrite laths. CCT-diagrams of the two bainitic steels have been determined, which showed that the structure of mixed bainite can be obtained in a wide range of cooling rate.At last, conclusion was obtained that the two bainitic steel were applicable to make frog and rail.
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