Numerical Simulation Of Solidification Process For Large Steel Casting And Optimization Of Parameters

The casting forming of the large steel of ZG0Cr13Ni4Mo and ZG230-450 were studied in this paper, and a database for materials property parameters used in numerical simulation of the large steel casting is built in this study, and the thermo-physical parameters of the two typical materials are got through the experimental measurement. At the same time, an experimental model of the heavy steel casting is designed and the law of variation of the interfacial heat-transfer coefficient with temperature between casting and mold during solidification of the heavy steel casting through anti-calculation with the application of ProCAST with the actual pouring casting. Using the experimental casting, critical values of NIYAMA criterion for shrinkage porosity prediction of the large steel casting of the two typical materials are obtained by the contrast method. Besides, the parameters obtained in the study are applied in the numerical simulation and process optimization for a large frame, and provide accurate parameters for the guidance of the large steel casting production with numerical simulation.The application of database technology in the solidification simulation can significantly improve the accuracy and efficiency of simulation. Based on the Relation Model, a database for materials thermo-physical parameters of the large steel casting the study is built with the database management system ACESS. The database can inquire about the thermo-physical parameters of some commonly used cast steel materials, molded materials, refractory insulation materials in solidification process simulation of the large steel casting as well as the interfacial heat-transfer coefficient between casting and mold and critical values of criterion to predict the shrinkage porosity that are obtained in the present study. Meanwhile, the thermo-physical properties of ZG0Cr13Ni4Mo and ZG230-450 are measured by Laser Flash Method, and the other materials thermo-physical parameters are obtained from the other calculation software and related literature material.A test casting with characterizing size of the large steel casting is designed and cast. The temperature in the casting and mold nearby the typical interfaces during solidification are actually measured, and the interfacial heat-transfer coefficient between the casting and mold in different temperature are calculated by using the anti-calculation module of ProCAST. At the same time, the changing size of gas gap in the interface, and the law of the interfacial heat-transfer coefficient changing with air gap width are investigated in the study. By using the ultrasonic flaw detector, the distribution of shrinkage porosity of test casting made of ZG0Cr13Ni4Mo and ZG230-450 are detected. As compared with the simulation and prediction of ProCAST software, the critical values of NIYAMA Criterion which is used for predicting the shrinkage porosity of the large steel of two steel cast materials are determined.Based on the study above, the temperature of the large frame cast by two kinds of cold iron setting process program are calculated by using the thermo-physical parameter and the interfacial heat-transfer coefficient which have been obtained. Besides, shrinkage of two schemes is predicted by using the critical values which are investigated in the study, and the optimum process scheme is obtained finally.In the present study, the problem of key parameters in simulation and prediction for the large steel has been solved, and the investigation has important theoretical significance for improving the large steel casting production.