Papers by Author: Hong Sun Park

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Authors: Hong Sun Park, Hyung Ick Kim, Yong Huh, Moon Young Kim, Sang Yeol Park, Jae Mean Koo, Chang Sung Seok
Abstract: The Ni-based superalloy Inconel 718 (IN-718) was developed in the 1950s and is currently used for several critical gas turbine components due to its good balance of mechanical properties. Because of its stable mechanical properties at high temperature, the alloy is used for turbine bolts. The mechanical properties of in-service facilities are required to maintain safety operation in power plants. Ultrasonic tests, tensile tests and hardness tests were performed to evaluate the degree of the material degradation of Inconel 718. The mechanical properties decreased as degraded, but the longitudinal velocity of the ultrasonic signal increased. Also, the microstructure of the degraded Inconel 718 was to study the relationship between the result from ultrasonic test and the results from destructive methods.
Authors: Hyung Ick Kim, Hong Sun Park, Bong Kook Bae, Young Min Lee, Chang Sung Seok, Moon Young Kim
Abstract: The Ni-based superalloy GTD-111DS has been widely used as the material of the first stage blade of gas turbine. But there are little data available on the microstructure and mechanical property. The strength and ductility of GTD-111DS decrease more rapidly due to the acceleration of its microstructure degradation under high temperature. The results of study showed that the shape of γ' did not change with increased aging time but the amount and volume fraction of the deposition of secondary γ' increased and secondary γ' grew among primary γ'. Also there was difference of yield strength and tensile strength in room temperature according to heat treatment and collecting region.
Authors: Hyung Ick Kim, Hong Sun Park, Jae Mean Koo, Sung Ho Yang, Moon Young Kim, Chang Sung Seok
Abstract: The advancement in superalloys permits the hot gas path components to operate for thousands of hours under severe centrifugal, thermal and vibratory stresses. The blade of a gas turbine must withstand the most severe condition combined of temperature, stress, and environment. After a long operation, the damaged blades of a gas turbine used are welded for build-up and repaired. We analyzed and compared the mechanical properties of GMAW(Gas Metal Arc Welding), a manual welding method, a laser cladding method, and an automatic welding method under research and development.
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