Numerical Simulation Of Temperature Field During Casting Steel Quenching Process And Prediction Of Microstructure And Performance

Steel casting quenching process is a complex process which with temperature changes,organizational change and stress and strain, it is an important method to improve theperformance of steel casting after moulding by casting. The quenching process directly decidethe performance of steel casting whether meet the requirements. But adopts experimentalmethod to determine the appropriate correctness of steel quenching process, need a lot ofmanpower and material resources and time cost. And every experiment can only study a steelcasting quenching process with a particular component under specific process. Therefore,using the numerical simulation to caculate the temperature changes of steel castingquenching process, predict microstructure and performance and discuss the influence ofdifferent quenching process on the microstructure and mechanical properties of steelcasting and to seek the most appropriate way of steel quenching process has veryimportant practical significance.This thesis firstly studied the heat transfer principle in the process of steel quenchingprocess. Based on the heat conduction equation, a three dimensional mathematical model isestablished for the temperature field. This mathematical model consider the latent heat of steelcasting quenching process, the change of heat transfer coefficient of different cooling mediumand physical parameters of steel casting. Finite difference method is used to develop thecomputer program for calculating the temperature field of steel casting quenching process.One prediction method the Maynier’s model for forcasting the microstructure andmechanical properties of steel casting is put forward. Developed the system for thenumerical simulation of steel casting quenching process and prediction of microstructureand mechanical properties.Secondly, focusing on the ladder parts case study, the systematic analysis of influence ofthermal physical parameters of steel casting and the change of heat transfer coefficient ofdifferent cooling medium to the temperature field and microstructure and mechanical properties of steel casting after quenching are discussed. Importantly anlysisd thetemperature field and prediction results when steel casting cooling in the water, L-AN22total loss system oil and10%NaCl aqueous solution. The analysis results are conform tothe describtion of cooling capacity of three kinds cooling medium referred in otherthesis.Lastly, focusing on the brake wheel of crane case study, analysised the temperaturefield and the distribution of martensite, bainite, ferrite-pearlite and hardness in brake wheelafter quenching in water, oil, and water-cooling then oil quenching. We can known fromthe results that water-cooling then oil quenching not only can improve the hardness ofbrake wheel surface, but also can ensure that toughness of the center of brake wheel.