抄録
Creep deformation should be considered in the thermal deformation analysis of castings because the casting process includes a high-temperature region. For this reason, the thermal deformation of castings should be predicted by the so-called “elasto-plastic-creep FEM analysis.” However, this method is rarely applied for prediction as the pre-experiments take considerable time because the material constants for the analysis must be determined through long creep tests, under at least three stress conditions and at more than three temperatures, in addition to tensile tests.
To solve this problem, this paper describes an experimental method called “tension-strain maintenance test” that can estimate the material constants for elasto-plastic-creep analysis efficiently. The method was applied to SCS13 stainless cast steel, and the characteristics of its deformation at five temperatures were evaluated. Based on the evaluation results, the material constants of an elasto-plastic-creep model used for thermal deformation FEM analysis were determined, and using these material constants, elasto-plastic-creep FEM analysis was conducted to predict the thermal deformation of SCS13 generated in the cooling process of casting. The analysis results were compared with the results of ordinary elasto-plastic FEM analysis, and it was found that elasto-plastic FEM analysis may not be able to predict the thermal deformation of castings precisely. These results suggest that elasto-plastic-creep FEM analysis is better for predicting the thermal deformation of castings.
