A Study on the Effect of Microcast and Skull Centrifugal Cast on Microstructure and Mechanical Properties of IN-713LC Superalloy

摘要

The IN-713LC superalloy employed in this study was prepared by microcast and skull centrifugal cast processes, and then cast as standard test bars with different grain size. The bars were followed by HIP treatment. Thus, the effects of microcast and centrifugal cast on microstructures and mechanical properties of IN-713LC superalloy were investigated. The results showed that the microcast and centrifugal cast processes have refined the grain size of the test bars and the grain size of the fine grain were about 65 μm and 25 μm by microcast and centrifugal cast, respectively. From the microstructue observing results, it is known that the carbides morphology is refined and spheroidized, when the grain sizes of test bars are refined. Besides, HIP treatment eliminated micro-shrinkage porosity in the castings and improved mechanical behavior. After the test bars treated by HIP, the area fraction of microporosities in the centrifugal cast fine grain specimen could be eliminated from 7.7% to 0.8%. The tensile strength and the elongation also increased to 1328 MPa and 18.1% after HIP. For a creep-tested under 927 ℃/158 MPa, the creep life for the ultra-fine grain specimen (25 μm), obtained by centrifugal cast was higher than that the fine grain specimen (90 μ m) obtained by microcast process. In this study, the mechanical properties of the IN-713LC superalloy were significantly improved by microcast and centrifugal cast process. Besides, the HIP procedure could eliminate the detrimental effects on mechanical properties of microshrinkage porosity in the fine-grain castings.