Deformation Prediction of a Heavy Hydro Turbine Blade During the Casting Process with Consideration of Martensitic Transformation

Abstract

Heavy hydro turbine castings are made of martensitic stainless steel, which undergoes martensitic transformation during the casting process. Therefore, both residual stress and deformation are affected not only by uneven cooling but also by martensitic transformation. In this paper, a coupled thermo-martensitic phase transformation–stress model was established and it was implemented by further development with ABAQUS, which also incorporated the thermal and mechanical boundaries, and the contact pair between the casting and mold. The system was applied to the analysis of a heavy hydro blade casting. Results of stress, displacement, and martensite phase fraction were obtained. It is found that martensitic transformation has a significant effect on the stress and deformation results. The displacement in the normal direction of local areas was calculated to represent deformation in the x, y, and z directions. The deformation of the blade casting occurred mainly at the two thin corners with 18 and 22 mm in opposite tendency. The simulated results were compared with the measured machining allowance, and they are basically in agreement.