Investigation on Material's Fatigue Property Variation Among Different Regions of Directional Solidification Turbine Blades—Part II: Fatigue Tests on Bladelike Specimens

Abstract

Part I of this investigation is mainly focused on fatigue tests of full scale turbine blades, based on the observation of the phenomena that some directional solidification (DS) blades do not fracture at their maximum stress region, and it has been revealed that there exists material's fatigue property variation among different regions of DS blades. For more indepth and quantitative study on the fatigue property variation, Part II of this investigation designs and fabricates four types of DS bladelike specimens (including platform, shroud, body, and rootlike specimens), which imitate the geometry, microstructure, and stress features of a full scale turbine blade on its four typical regions, to conduct the low cycle fatigue (LCF) tests. Test results show that the bodylike specimen has the best fatigue performance, and under the same stress state, the fatigue life of root, shroud, and platformlike specimens are 29.1%, 28.5%, and 13.7% of the bodylike specimen, respectively. The large material's fatigue property variation among different regions of DS blades should be considered in future blade life design.