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103 results on '"Kim, Eung-Seon"'

21. A review of low-cycle fatigue of Alloy 617 for use in VHTR components: Experimental outlook

Author

Dewa Rando Tungga, Park Jeong-Hun, Kim Seon-Jin, Kim Woo-Gon, Kim Eung-Seon, Haryadi Gunawan D., and Ekaputra I. M. W.

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

The effect of strain range and temperature on the low-cycle fatigue behaviour and microstructure change during cyclic deformation of Alloy 617 for use in very high temperature gas-cooled reactor components were studied at elevated temperature starting from ambient condition. Increasing the strain range and the temperature was noticed to reduce the fatigue resistance of nickel-based Alloy 617 due to facilitating the transformation behavior of the carbides in the grain interior, precipitates along the grain boundary, and oxidation behavior inducing surface connected precipitates cracking. Initial hardening behavior was observed at room temperature condition during cyclic due to the pile-up dislocation of micro-precipitates. The grain size was also taking a role due to the formation of an obstacle in the matrix. In the high temperature regime, the alloy 617 was found to soften for its entire life due to the fast recovery deformation, proved by its higher plasticity compared with lower temperature. The deformation behavior also showing high environmentally assisted damage. Oxidation behavior was found to become the primary crack initiation, resulting in early intergranular surface cracking.

Published
2018
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34. Effects of Surface Roughness on the Thermal Emissivity of IG-11 Graphite for Nuclear Reactor

Author

Kim Suk Hwan, Seo Seung-Kuk, Kim Hye Sung, Chi Se-Hwan, Roh Jae-Seung, and Kim Eung-Seon

Subjects
Materials science, law, Modeling and Simulation, Metals and Alloys, Emissivity, Surface roughness, Graphite, Nuclear reactor, Composite material, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, law.invention, Nuclear chemistry
Published
2011

35. Nuclear Graphites (II) : Mechanical Properties

Author

Kim Eung-Seon, Choi Woong-Ki, Park Soo-Jin, Chi Se-Hwan, and Kim Byung-Joo

Subjects
Inorganic Chemistry, Materials science, Renewable Energy, Sustainability and the Environment, Process Chemistry and Technology, Organic Chemistry, Metallurgy, Materials Chemistry, Ceramics and Composites, Energy Engineering and Power Technology
Published
2010

36. Influence of Dynamic Strain Aging on Tensile Deformation Behavior Of Alloy 617

Author

Ekaputra, I.M.W., Kim, Woo-Gon, Park, Jae-Young, Kim, Seon-Jin, and Kim, Eung-Seon

Abstract

To investigate the dynamic strain aging (DSA) behavior of Alloy 617, high-temperature tensile tests were carried out with strain rates variations of 10−3/s, 10−4/s, and 10−5/s from 24°C to 950°C. Five flow relationships, Hollomon, Ludwik, Swift, Ludwigson, and Voce, were applied to describe the tensile true stress–strain curves, and the DSA region was defined. In describing the tensile curves, Ludwigson's equation was superior to the other equations, and the DSA region was adequately defined by this equation as plateaus at intermediate temperatures from 200°C to 700°C. It was identified that Alloy 617 is dominated by three types of serrations, known as Types D, A+B, and C. The activation energy values for each serration type were obtained by the Arrhenius equation. By using the obtained activation energy values, the serrated yielding map and the DSA mechanism were drawn and manifested. In addition, the relationship between the tensile strength and strain rate at higher temperatures above 700°C was found to be closely related to the amounts of slip lines. In the scanning electron microscope (SEM) fractographs, there was a significant difference at the low, intermediate, and high temperatures, but almost the same to the three strain rates.

Published
2024
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