http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
니켈계 합금 용접부의 미세조직 및 기계적 특성에 대한 장기 열적 시효의 영향
유승창,함준혁,김지현,Yoo, Seung Chang,Ham, Junhyuk,Kim, Ji Hyun 한국압력기기공학회 2016 한국압력기기공학회 논문집 Vol.12 No.1
To investigate the effect of long-term thermal aging on the microstructural and mechanical characteristics of weldment made of nickel base alloy and its weld metal, an accelerated heat treatment was applied to simulate the process of long-term thermal aging in the operating condition of nuclear power plant. A representative nickel-based weldment with Alloy 600 and Alloy 182 was fabricated and heat-treated at $400^{\circ}C$ for 1,713 h and 3,427 h to simulate the thermal aging for the period equivalent to 15 and 30 years in operating pressurized water reactors, respectively. The microstructural and mechanical characteristics were analyzed by using optical microscopy, scanning electron microscopy and Vickers microhardness measurement. Changes were observed in precipitation behavior and microhardness of each specimen, and these changes were mainly attributed to the change in precipitated morphology and residual stress across the weld during the thermal aging process.
Alloy 600의 PWSCC에 미치는 열적 시효 및 삼축 응력의 영향
유승창(Seung Chang Yoo),김종성(Jong Sung Kim),황일순(Il Soon Hwang),김지현(Ji Hyun Kim) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
In this study, the effects of triaxial stress was investigated in terms of primary water stress corrosion susceptibility. Thermally aged Alloy 600 specimens were prepared via accelerated heat treatment at 400 ℃ which is one of the highest temperature which will not cause the formation of excessive carbides or precipitates which will not be formed at nuclear power plant primary circuit environment. Triaxial stress was then applied by making round notch at the surface of round tensile specimen. The crack initiation time ere measured in-situ by direct current potential drop method during slow strain rate test at primary water condition. At the notched specimen, cracks were mainly observed at the region where shear stress is focused. Also, the stair shape of fracture surface was observed, which might cause by enhanced localized plasticity and multiple number of activated slip system under triaxial stress state.
삼축 응력이 인가된 Alloy 600의 일차수 응력부식균열 거동에 대한 연구
유승창(Seung Chang Yoo),최경준(Kyoung Joon Choi),김지수(Ji-Soo Kim),최병호(Byoung Ho Choi),김윤재(Yun-jae Kim),김종성(Jong Sung Kim),김지현(Ji Hyun Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In this study, the effects of triaxial stress was investigated in terms of primary water stress corrosion susceptibility. Thermally aged Alloy 600 specimens were prepared via accelerated heat treatment at 400 °C which is one of the highest temperature which will not cause the formation of excessive carbides or precipitates which will not be formed at nuclear power plant primary circuit environment. Triaxial stress was then applied by making round notch at the surface of round tensile specimen. The crack initiation time ere measured in-situ by direct current potential drop method during slow strain rate test at primary water condition. At the notched specimen, cracks were mainly observed at the region where shear stress is focused. Also the stair shape of fracture surface was observed, which might cause by enhanced localized plasticity and multiple number of activated slip system under triaxial stress state.
원전 이종금속 용접부의 장기 열적 시효에 따른 미세조직 및 기계적 특성변화에 관한 고찰
최경준,유승창,김지현,Choi, Kyoung Joon,Yoo, Seung Chang,Kim, Ji Hyun 한국압력기기공학회 2014 한국압력기기공학회 논문집 Vol.10 No.1
In this study, the metallurgical analysis and mechanical property measurement have been performed to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at $450^{\circ}C$ for 2,750 hours. The microstructural characterization was conducted mainly near in a weld root region by using optical microscopy, scanning electron microscopy, transmission electron microscopy. And the mechanical properties were measured with Vickers microhardness test and nanoindentation method. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. Type-II boundaries were found in weld side of DMW and the hardness was the highest at the narrow zone between Type-II boundary and fusion boundary.
Alloy 182 PWSCC 개시저항성에 대한 열적시효와 냉간가공의 영향
박재필(Jae Phil Park),유승창(Seung Chang Yoo),김지현(Ji Hyun Kim),반치범(Chi Bum Bahn) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
We investigated the effect of thermal aging and cold working on the primary water stress corrosion cracking susceptibility of Alloy 182 weld. To simulate 15 and 30 years of equivalent plant operating condition, an accelerated heat treatment at 400℃ was performed. A cold rolling with 20% of thickness reduction was performed for the cold-worked condition. After the heat treatment and cold rolling, tensile test and U-bend specimens were fabricated from a weld deposited parent specimen. At room temperature tensile test, it was shown that the tensile strength increased for both the thermally aged and cold worked specimens and the elongation decreased for the cold worked specimens. The PWSCC initiation test indicated that the PWSCC susceptibility for Alloy 182 was decreased until 15 years of thermal aging, and then increased thereafter. For the case of cold worked specimens, high susceptibility of PWSCC initiation was observed.