샤피 V - 노치 충격 하중-변위 곡선의 균열정지하중을 이용한 원자로압력용기강의 파괴인성 예측

박정용; 김주학; 이윤규; 홍준화; Jeong-Yong Park; Joo-Hag Kim; Yun-Kyu Lee; Jun-Hwa Hong

Korean Journal of Materials Research, Vol.10, No.4, 305-311, April, 2000

Fracture Toughness Prediction of RPV Steels Using Crack Arrest Load of Load-Displacement Curve in Charpy V - Notch Impact Test

박정용, 김주학, 이윤규, 홍준화

한국원자력연구소 원자력재료기술개발팀

Jeong-Yong Park, Joo-Hag Kim, Yun-Kyu Lee, and Jun-Hwa Hong

Nuclear Materials Technology Development Team, Korea Atomic Energy Research Institute, Taejeon 305-353, Korea

초록

샤피 V-노치 충격 하중-변위 곡선으로부터 얻은 균열정지하중을 이용하여 원자로압력용기강의 균열정지파괴인성( K Ia )을 예측할 수 있는 방법을 모색하고 그 타당성을 고찰하였다. 샤피충격 하중-변위 곡선으로부터 얻은 균열정지하중값의 변화는 특성온도로 보정된 지수함수의 형태로 잘 표현될 수 있었다. 특성온도 T Pa=2kN 은 실험적인 무연성천이온도( T NDT ) 및 T 41J 과 높은 상관성을 나타냈으며, 원자로압력용기강의 균열정지파괴인성을 표현하는 새로운 특성온도로 사용할 수 있을 것으로 판단되었다. 또한 균열정지하중값의 변화는 파면으로부터 측정된 안정균열길이의 변화와 매우 높은 상관성을 나타내었다. 따라서 무딘 노치를 갖는 시편에 대한 계장화샤피충격시험을 통하여 균열정지하중 및 안정균열길이를 측정하믈써 비교적 정확하게 원자로압력용기강에 대한 하한값의 파괴인성치( K Ia )를 평가하는 것이 가능한 것으로 판단되었다.

toughness of nuclear reactor pressure vessel (RPV) steels (ASME SA508 Cl.3). The temperature dependence of the crack arrest load was well described by the type of exponential function characterized by an index temperature at which the crack arrest load is 2kN. The specific index temperature, which also well correlated with T NDT andT 41J is expected to be representative index temperature characterizing the crack arrest fracture toughness of RPV steels. Also, the crack arrest load correlated well with the stable crack length measured from the fracture surface. From the measurements of the crack arrest load and the stable crack length, the lower bound fracture toughness, K Ia of RPV steels could be predicted with sufficient accuracy.

Keywords:RPV steels;fracture toughness;crack arrest load

[References]

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[1] Iskander SK, Nanstad RK, Sokolov MA, McCabe DE, Hutton JT, Thomas DL, Nanstad RK(ed.), Hamilton ML(ed.), Garner FA(ed.), Kumar AS(ed.), ASTM STP 1325, ASME, 204 (1999)

[2] Fabry A, Van Walle E, Van de Velde J, Chaouadi R, Puzzolante JL, Van Ransbeeck T, Verstrepen A, Van Walle E(ed.), Mechanical Engineering Publication, 59 (1996)

[3] Schindler HJ, Varga Tm Njo DH, Prantl G, International Symposium on Materials Ageing and Component Life Extension, 1367 (1995)

[4] Bohme W, Van Walle E(ed.), Mechanical Engineering Publication, 1 (1996)

[5] ASTM Standard E-33/ 1994 (1994)

[6] Ireland DR, et al., ETI Technical Report 75-43, EPRI (1975)

[7] ASTM Standard E-636/ 1983 (1983)

[8] Kim JH, Kim H, Chi SH, Hong JH, Jung IS, Hong HS, Proc. of the 3rd Symp. on Integrity Evaluation Technique of Nuclear Components, KINS, 1 (1996)

[9] Kim H, Kim JH, Chi SH, Hong JH, Journal of the Korean Society of Mechanical Engineers, 21(1), 93 (1997)

[10] Nanstad RK, et al., ASTM STP 1248, 111 (1995)

[11] ASTM Standard E-399/ 1994 (1994)

[12] Srawley JE, International Journal of Fracture Mechanics, 12(6), 475 (1976)