한국재료학회지 · 한국재료학회

Research Paper

Heat Treatment and Mechanical Property Behavior of 3.5NiCrMoV Steel for Gas Turbine Compressors
가스터빈 압축기용 3.5NiCrMoV 강의 열처리물성 거동

Suseong Kang, Joonghoon Kim, Changwoo Lee, Jaeho Jang, Hyoung Chan Kim, Byung Jun Kim, Sanghoon Noh, Byoungkoo Kim
강수성, 김중훈, 이창우, 장재호, 김형찬, 김병준, 노상훈, 김병구

This study investigates optimization of the heat treatment processes for a 35-ton 3.5NiCrMoV steel forging intended for gas turbine compressor applications. Gas … + READ MORE

This study investigates optimization of the heat treatment processes for a 35-ton 3.5NiCrMoV steel forging intended for gas turbine compressor applications. Gas turbines are critical power generation facilities that operate under extreme conditions, with compressor components enduring temperatures above 500 °C, high-speed rotation, and significant stress. There is an urgent need to develop independent domestic technology for these components, as advanced nations restrict technology transfer. This study proposes replacing expensive imported nickel alloys with 3.5NiCrMoV steel, traditionally used for steam turbine rotors, to reduce costs and ensure supply chain stability. To meet the demanding requirements for higher strength, ductility, and toughness in gas turbine environments, a systematic study on optimizing the heat treatment process was conducted. The methodology involved composition analysis via precision spectroscopy, thermodynamic modeling of phase transformation behavior validated by dilatometer experiments, and CCT curve analysis to determine critical cooling rates for robust bainite phase formation. Heat treatment master curves based on quenching and tempering temperatures were derived to identify candidate conditions, and the resulting tensile, hardness, and impact toughness properties were evaluated. Finally, by analyzing the correlation between microstructure and mechanical properties, an optimized quenching and tempering process for gas turbine compressor applications was established. - COLLAPSE

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27 August 2026
Research Paper

Effect of Si and Cu Addition on Hydrogen Embrittlement of Ferrite-Pearlite Steels
페라이트-펄라이트강의 수소취성에 미치는 Si와 Cu 첨가의 영향

Jaeseok Oh, Yena Hwang, Su-Hwan Choe, Min-Seop Jeong, Seokwoo Ko, Byoungchul Hwang
오재석, 황예나, 최수환, 정민섭, 고석우, 황병철

This study investigated how adding Si and Cu affected the hydrogen embrittlement behavior of ferrite–pearlite steels by correlating microstructural characteristics with fracture … + READ MORE

This study investigated how adding Si and Cu affected the hydrogen embrittlement behavior of ferrite–pearlite steels by correlating microstructural characteristics with fracture behavior and hydrogen trapping behavior. The Base, Si-added, and Cu-added specimens were characterized using microstructural observation, tensile testing, slow strain-rate test (SSRT) under electrochemical hydrogen charging, thermal desorption analysis (TDA), and silver decoration. The Si-added specimen exhibited the smallest ferrite grain size and the lowest pearlite fraction, whereas the Cu-added specimen showed the highest pearlite fraction. Under hydrogen charging, the Si-added specimen exhibited the highest relative notch tensile strength (RNTS), while the Cu-added specimen showed the lowest RNTS. Fractographs and cross-sectional analyses revealed a tearing topography surface (TTS) near the notch region and secondary cracking in pearlite, indicating that cracks preferentially initiated within the pearlite. The Si-added specimen also showed more frequent crack deflection during propagation, suggesting improved resistance to crack propagation. TDA and silver decoration further suggested that ferrite–cementite interfaces in pearlite could be associated with hydrogen trapping. These results indicate that the hydrogen embrittlement behaviors of ferrite–pearlite steels were governed by the combined effects of pearlite-related crack initiation, hydrogen trapping, and crack propagation resistance associated with ferrite grain refinement. - COLLAPSE

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27 August 2026