Numerical simulation of flow, temperature and phase fields in U71Mn rail-head quenching process

Li Gongfa, Liu Jia, Jiang Guozhang, Kong Jianyi, Xie Liangxi, Xiao Wentao, Zhang Yikun, Cheng Fuwei

COMPUTER MODELLING & NEW TECHNOLOGIES 2014 18(1) 61-70

College of Machinery and Automation，Wuhan University of Science and Technology, 430081, China

With the sustainable and fast development of Chinese economy, the volume of railway freight was increasing, and which promoted the train load and speed continue improving, in order to meet the needs of high speed and over loading trains’ running, heavy and seamless steel rail has increasingly widely used Heat-treatment was emphasized for its important role to qualify the products of heavy rail. And air-cooling quenching was one of the widely used heating process methods. Air-jet is a very vital instrument in quenching by air-cooling. At present, the international community has been widely used air-cooled quenching, most quenching production lines of domestic converted into wind cold quenching line. It is necessary to simulate the inner and outer flow-field of air-jet. In this paper, by means of computational fluid dynamics soft system Fluent to establish the geometric model of heavy rail, analysis the distribution of the internal and external flow field about air-jet centre cross section and the three sections were in parallel with it. Then through setting surface heat transfer coefficient of air-cooling, numerical simulation of temperature field in the cooling process of heavy rail. Finally, the phase changing temperature of steel U71Mn was got based on its CCT curves. With the cooling curves of several key points, the cooling rate at phase transition point was calculated. By comparing with every microstructure’s critical cooling rate, the final cooling microstructure was predicted. Relative tests showed that the prediction was reasonable. It is significantly valuable for parameters’ selection in heavy rail’s technical operation.