Numerical Simulation and Experimental Study on Heat Treatment Process of U20Mn Bainite Rail

In order to better optimize the heat treatment process of bainite rail, the mathematical model of the heat treatment process of U20Mn new bainite rail is established by using DEFORM software, and verified by experiments. The results show that, during the cooling process, the rail head tread is in the form of back temperature slow cooling, and the rail center is in the form of direct slow cooling; after heat treatment, the bainite transformation of the rail head tread and the rail bottom edge is the least and the hardness is the highest; the center of the rail head and rail bottom have the slowest cooling speed, the largest amount of bainite transformation, and the lowest hardness. With the increase of the depth from the tread, the rail hardness first decreases and then increases. The relationship between the rail head hardness and the microstructure transformation is fitted: hardness = 48.969 − 0.0897 × f ( B )= 39.988 + 0.0961 × f ( M ), and the accuracy of the simulation results is verified by metallographic experiments and the color metallographic method, providing technical support for the further development of the high strength and toughness of heat-treated bainite rail.