Ni-Mo-Cr계 저합금강의 천이온도영역에서의 파괴인성에 미치는 Ni 및 Cr 함량의 영향 (Effects of Ni and Cr Contents on the Fracture Toughness of Ni-Mo-Cr Low Alloy Steels in the Transition Temperature Region)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 47권 / 9호 / 533 ~ 541페이지
· 저자명 : 이기형, 박상규, 김민철, 이봉상, 위당문

초록

Materials used for a reactor pressure vessel(RPV) are required high strength and toughness, which
determine the safety margin and life of a reactor. Ni-Mo-Cr low alloy steel shows better mechanical properties
than existing RPV steels due to higher Ni and Cr contents compared to the existing RPV steels. The present
study focuses on effects of Ni, Cr contents on the cleavage fracture toughness of Ni-Mo-Cr low alloy steels
in the transition temperature region. The fracture toughness was characterized by a 3-point bend test of
precracked Charpy V-notch(PCVN) specimens based on ASTM E1921-08. The test results indicated that the
fracture toughness was considerably improved with an increase of Ni and Cr contents. Especially, control of
Cr content was more effective in improving fracture toughness than manipulating Ni content, though Charpy
impact toughness was changed more extensively by adjusting Ni content. These differences between changes
in the fracture toughness and that in the impact toughness were derived from microstructural features, such
as martensite lath size and carbide precipitation behavior.

영어초록

Materials used for a reactor pressure vessel(RPV) are required high strength and toughness, which
determine the safety margin and life of a reactor. Ni-Mo-Cr low alloy steel shows better mechanical properties
than existing RPV steels due to higher Ni and Cr contents compared to the existing RPV steels. The present
study focuses on effects of Ni, Cr contents on the cleavage fracture toughness of Ni-Mo-Cr low alloy steels
in the transition temperature region. The fracture toughness was characterized by a 3-point bend test of
precracked Charpy V-notch(PCVN) specimens based on ASTM E1921-08. The test results indicated that the
fracture toughness was considerably improved with an increase of Ni and Cr contents. Especially, control of
Cr content was more effective in improving fracture toughness than manipulating Ni content, though Charpy
impact toughness was changed more extensively by adjusting Ni content. These differences between changes
in the fracture toughness and that in the impact toughness were derived from microstructural features, such
as martensite lath size and carbide precipitation behavior.

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