The Research On Prediction Of Microstructure And Performance During Casting Steel Solidification And Heat Treatment Process

The steel casting is widely used in the mechanical parts, the quality of the steel casting determines the performance and life of the mechanical parts, and its quality is determined by the microstructure and performance. Therefore, in order to obtain high quality steel, microstructure should be reasonably controlled. At present, casting and heat treatment are important technology to control microstructure. Studying the relationship of casting and heat treatment process and microstructure, the numerical simulation method is a hot spot. Previous numerical simulation method is mainly studying casting process or heat treatment process, separately. As-cast microstructure and performance is the final microstructure and mechanical performance of steel casting. Numerical simulation of heat treatment process is separated from the initial state of steel. Therefore, using the numerical simulation of casting solidification process combined with heat treatment process, that will be more close to the actual situation, which ensure that the simulation results accord with the actual result. In this paper, research work is as follows:Firstly, putting forward the method of predicting the microstructure and performance of steel casting, this method is on the basis of numerical simulation's results of the three dimensional temperature field. Mainly dividing into two steps: the Gaussian continuous nucleation model is used to predict nucleation number, and derive the casting grain size. Based on software of JMatPro, database of microstructure and performance is established. Using the technology of data quick search and the assignment of grid can get the microstructure and performance of the whole casting.Secondly, using the mapping technology to combine the casting solidification process and heat treatment process, the steel casting as-cast microstructure is regarded as the initial microstructure of the heat treatment. The principle of superposition is to discrete continuous heating or cooling process for several tiny isothermal phase. The curves of TTA and TTT are used to calculate the incubation period of phase transformation and phase transition. And the weighted average method for single-phase hardness is applied to calculate steel casting hardness.Finally, through the actual steel casting experiment, heat treatment experiment, the metallographic analysis and hardness test, the results show that, the method of forecasting microstructure and performance of steel casting solidification and heat treatment process can accurately and reliably predicts distribution of microstructure and performance. And, the forecast system of microstructure and performance of steel casting solidification and heat treatment process is applied to the frame of steel casting, showing that the method can provide guidance for practical production.