Rejuvenation of IN738LC gas-turbine blades using hot isostatic pressing and a series of heat treatments
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DOI 10.1007/s12206-020-1018-2
Journal of Mechanical Science and Technology 34 (11) 2020 Original Article DOI 10.1007/s12206-020-1018-2 Keywords: · Gas turbine · Hot isostatic pressing · Series of heat treatment · Rejuvenation
Rejuvenation of IN738LC gas-turbine blades using hot isostatic pressing and a series of heat treatments Sungho Yang1, Junghan Yun2 and Chang-Sung Seok2 1
Correspondence to: Chang-Sung Seok [email protected]
Citation: Yang, S., Yun, J., Seok, C.-S. (2020). Rejuvenation of IN738LC gas-turbine blades using hot isostatic pressing and a series of heat treatments. Journal of Mechanical Science and Technology 34 (11) (2020) 4605~4611. http://doi.org/10.1007/s12206-020-1018-2
Received February 26th, 2020 Revised
July 9th, 2020
Accepted August 11th, 2020 † Recommended by Editor Chongdu Cho
Graduate School, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 4402 746, Korea, School of Mechanical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 440-746, Korea
Abstract
The maintenance of the gas turbine blades is important because these blades are operated in harsh conditions. Therefore, nickel-based superalloys that offer excellent performances in high-temperature conditions are typically used, and the blades are inspected and replaced based on the manufacturer’s maintenance standards. However, the service life can be extended by refurbishing the blades that have exceeded their warranty life, based on the manufacturer criteria. In this study, 10 rejuvenation conditions that consist of ‘hot isostatic pressing and series of heat treatment’ were applied to the blades that operated in domestic environments and had exceeded their warranty life. First, through microstructure analysis, by comparing the shape of the gamma prime phase according to the change of the full solution temperature, the optimal full solution temperature was selected to be 1200 °C or more and less than 1220 °C. Based on this, the tensile properties according to the presence or absence of HIP process and the detailed heat treatment conditions were evaluated, and the optimal rejuvenation conditions was selected by comparing tensile strength, yield strength, and elongation values. Finally, to verify the selected rejuvenation condition, the creep durability was evaluated, and it was confirmed that the creep life of the used material with a reduced creep life of 40 % compared to the new material was restored similarly to the new material.
1. Introduction
© The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Globally, the proportion of fossil fuels in electricity demand is expected to gradually decrease, and despite the expansion of the proportion of renewable energy to reduce greenhouse-gas (GHG) emissions, electricity production using natural gas is expected to remain at a similar level [1]. The role of power-generation facilities that use natural gas as the fuel is expected to become more important in the future as the a
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