Intensive riser cooling of a turbine blade steel casting after solidification

Abstract

To improve the production efficiency and reduce residual stress and deformation, a new method-Post Solidification Intensive Riser Cooling (PSIRC) was proposed for heavy steel castings. Risers are cooled by forced air from its top surface as the solidification of a casting finishes, so, the risers are turned into cooling passages during the cooling process of a casting with contrast to their function of feeding passages during the solidification process. This method was applied to a hydro turbine blade with 0.9 ton melt. Its cooling speed increased apparently meanwhile with improved temperature distribution uniformity and the hot spot was pushed almost to the casting bottom. The cooling efficiency was improved 40% before shakeout and its residual stress was reduced meanwhile.