Study On The Optimization Of Computer Simulation For The Quenching Process Of Several Steels

Based on the theories of thermodynamics and phase transformation, by using the Finite Element Method and the model of P.Maynier phase transformation and quenching hardness, calculations are carried out to simulate the quenching process of large-scale P20 steel mould, T8 steel and 45 steel with the shape of rectangle and cylinder respectively. This article puts emphasis on predicting the three-dimensional fields of transient quenching temperature, phase change and hardness of the try mentioned above. In order to verify the results of numerical calculation, some measures are made such as testing the fields of temperature and hardness, comparing with pertinent published data and observing the microstructure.In the model of this article, the nonlinear characteristic of physical property coefficients and the changes of surface convective heat tranfer coefficient are taken into account comprehensively. The effects of latent heat induced by microstructural transformation are also considered by coupling with temperature fields. On the platform of Finite Element Code--ANSYS, a calculating program are designed according to the quenching conditions of try. The cooling velocity of node at the point of 700℃ has a great influence on the following simulation of microstructure and hardness fields. So the data educed from ANSYS software is treated by the mathematic method of least-square fragmented curve-fitting and differential coefficient on the basis of Excel software. To get an accurate and steady result and save the computing time, several effective methods are employed to reduce the interferences, such as refinning the element on the surface of the model and changing the time substep. The calculating results of cooling temperature fields, microstructural transformation and hardness fields are in agreement with the measured ones well, which indicates that the model and calculating program can correctly predict the 3-D nonlinear and transient temperature fields of work pieces with complex shape.The contents of computer simulation on temperature fields, microstructure fields and properties in quenching process of work pieces are large and complex, there are a lot of problems to be solved. This article lays a foundation for the future research in this area. With the development of Finite Element theory and the perfecting of physical property coefficients, the simulation results will be in agreement with pratice better.