A study on the numerical simulation of thermal stress during the solidification of shaped castings

In order to study the development of thermal stress and to predict the hot tearing and residual stress of shaped casting, two models were used to carry out the stress analysis of the two stages of solidification. The rheological model [H]–[H|N]–[N|S] was used for the quasi-solid zone while the thermo-elasto-plastic model was used for the period after solidification. Coupling the thermal analysis based on the finite different method with the stress analysis based on the finite element method, a FDM/FEM integrated system of thermal stresses analysis during the solidification process was developed. After experimental verification, the system was put into practical application. The analysis results during the quasi-solid zone show that the visco-plastic strain is an important factor for the occurrence of hot tearing. The hot tearing of a case steel casting and the residual stresses and deformation of a hydro-turbine blade steel casting were analyzed and predicted using the system. The simulation and the practical results were basically in agreement.