Thin-wall debit effect on creep properties of single crystal superalloys

Abstract

The thin-wall effect of single crystal superalloys refers to the phenomenon that when the thickness of the sample and the part is less than 1 mm，the lasting life is reduced， the creep rate is increased and other mechanical properties are significantly attenuated. With the development of the internal cooling structure of advanced aero-engine single crystal blade parts， the structural thickness of some areas decreases， making it a typical thin-walled structure. Thus， it is of great engineering significance to consider the thin-wall effect in the thin-wall region during the design and manufacture of blades. Creep performance is one of the most important properties of superalloys for turbine blade application. This paper summarizes the thin-wall effect in creep performance of the superalloys as well as some advanced experimental equipment in the study of thin-wall effect. Research on thin-wall debit effect of superalloys can be divided into two categories，one is the cause of thin-wall debit，including the relative enhancement of oxidation，more significance in anisotropy，changes in microstructure and the initiation or growth of defects，and the factors that influence the thin-wall debit effect including experimental conditions（temperature，stress，etc.），the processing methods（casting， machining）， geometric shape （rectangular cross-section， ring cross-section， film cooling holes）. Research on thin-wall debit effect is within the scope of engineering application，as a part of “component level/analog component level” in “building block” verification and evaluation technology，thin-wall debit effect research under service environment or near-service environment conditions is more valuable for application. For this purpose，a variety of advanced experimental equipment platforms have been developed to simulate one or several coupled service conditions（high temperature，high pressure，corrosion/erosion，centrifugal loading） of the blade in the engine. Future research on thin-wall effects should be carried out under conditions closer to actual service conditions by preparing specimens according to the actual blade manufacturing process and conducting experiments on the equipment that simulates the service environment.

Keywords

• single crystal superalloys
• thin-wall debit effect
• thin section effect
• creep
• service condition