Through process numerical simulation of a heavy hydro turbine blade casting

Abstract

Heavy Hydro turbine castings, made of martensitic stainless steel, of spatially twisted shape, are susceptible to deformation during both casting and heat treatment processes. During production, uneven heating and cooling, phase transformation, stress and stain are responsible for the deformation of castings. However, the current research most focus on casting process or heat treatment process or both but separately, martensitic phase transformation is usually neglected in casting process. In this paper, a coupled thermo-martensitic phase transformation-stress model is established. And it is implemented by secondary development of ABAQUS, which deals the finite element model change and incorporates multi thermal and mechanical boundaries during casting and heat treatment processes as well, such as the contact pair between casting and mold during casting process. The stress analysis of a heavy hydro blade casting was performed by this system. The stress, displacement and phase are obtained. The effect of martensitic phase transformation on the stress and deformation is discussed. The simulated deformation is compared with measured results, and their agreement is improved by the through process simulation.