• 한국해양공학회지
• /
• 제14권1호
• /
• pp.44-51
• /
• 2000

Safety and integrity are required for reactor pressure vessels because they are operated in high temperature. There are single specimen method multiple specimen method and load ratio analysis method which used as evaluation of safety and integrity for reactor pressure vessels. In this study the fracture resistance curve(J-R curve) elastic-plastic fracture toughness($J_{IC}$) and material tearing modulus ($T_{mat}$) of SA 508 class 3 alloy steel used as reactor pressure vessel steel are measured and evaluated at room temperature 20$0^{\circ}C$ and 30$0^{\circ}C$ according to unloading compliance method and load ration analysis method. And then the comparison with experimental $J_{IC}$ and theoretical$J_{IC}$ by local fracture strain is managed.

• 대한기계학회논문집
• /
• 제8권5호
• /
• pp.469-475
• /
• 1984

본 연구에서는 구조물 경량화재료로서 변형거동이 현저히 다른 마르텐사이트 와 페라이트로 이루어진 복합조직강의 파괴인성에 관한 기본적 자료를 얻기 위하여 이 강을 모델재로서 준비하고 균열선단에서의 미시파괴기구 및 JSME Sool의 평가법을 이 용한 파괴인성에 대하여 검토하였다.

• 한국안전학회지
• /
• 제16권4호
• /
• pp.14-21
• /
• 2001

SG-365 steel is an important material End used for manufacturing a pressure vessel and gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the unloading compliance method according to the ASTM E8l3-97 and E1152-97 method on the smooth and side groove In specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the $J_{IC}$. Because it is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides. it improves the accuracy of toughness values, decreases the scattering of them and crack tunneling effect and shear lip by the side groove.

• 대한기계학회논문집A
• /
• 제30권10호
• /
• pp.1173-1178
• /
• 2006

In a primary reactor cooling system(RCS), a dissimilar weld zone exists between cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and $330^{\circ}C$, while no effect is observed in SA508 cl.3. The specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at $430^{\circ}C$, respectively. The specimens for elastic-plastic fracture toughness tests are according to the process in the thermal notch is created in the heat affected zone(HAZ) of CF8M and deposited zone. From the experiments, the $J_{IC}$ value notched in HAZ of CF8M presented a rapid decrease up to 300 hours at $430^{\circ}C$ and slowly decreased according to the process in the thermal aging time. Also, the $J_{IC}$ value presented a lower value than that of the CF8M base metal. And, the $J_{IC}$ of the deposited zone presented the lowest value of all other cases.

• 한국안전학회지
• /
• 제12권3호
• /
• pp.45-51
• /
• 1997

To evaluate the elastic-plastic fracture toughness by this modified offset method, the origin of J-R curve is set with drawing the blunting line on the maximum point of the negative crack growth and R curve is modified by adding the blunting factor of the experimented point on the R curve. The elastic-plastic fracture toughness $J_{IC]$ of A5083-H112 material by the modified offset method we 44kN/m on the smooth CT specimens.

• Journal of Welding and Joining
• /
• 제5권2호
• /
• pp.44-52
• /
• 1987

The fracture toughness, $J_{IC}$ of high frequency electric resistance welded steel pipe for smooth and side-grooved CT specimen was evaluated by unloading compliance method. The crack growth, .${\delta}a$ was obtained from the equation of Donald and Saxena & Hudak, and $J_{IC}$ was determined from the curve of J-${\delta}a$ relations. The crack growth on the experiment using unloading compliance method is underestimated as compared with ${\delta}a$ measured directly by the SEM, so the reliability of $J_{IC}$ from saxena & Hudak equation is large than that from Donald. The $J_{IC}$ value of side-grooved CT Specimen is estimated less than that of smooth, and this is the effect of the side-groove, the shear-lip of crack tip and the reduction of crack tunnelling phenomena.

• 한국해양공학회지
• /
• 제8권2호
• /
• pp.38-46
• /
• 1994

The method of JSME S001-83 and ASTM E813-87 have been adapted for evaluation of the elastic-plastic fracture toughness J sub(IC) of SB41 steel. This SB41 steel have the characteristics of low-stength CT specimens. The test results obtained have been considered and compared on the basis of resulted data from two kinds of methods(JSME S001-83, ASTM E813-87) and two kinds of specimen configurations(smooth, side-grooved). On the basis of results from consideration and comparison, the difficulties for its application were presented in case when the standard ASTM E813-87 method was employed for the measurement of J sub(IC) in SB41 steel. A modified method was applied for measuring J sub(IC) in SB41 steel that it used the blunting line real-measured by experiment instead of the standard blunting line theoretically determined, and the result from that procedure was analyzed and the usefulness of that method was examined and considered.

• 대한기계학회논문집
• /
• 제16권8호
• /
• pp.1421-1428
• /
• 1992

본 연구에서는 실제 고온, 고압용기에 장기 사용하여 재료 특성이 변화된 열 화재와 열화재를 열처리하여 충격치를 회복시킨 회복재의 두 종류의 재료를 사용하여 탄소성 파괴 인성치 J$_{IC}$실험을 수행하여 장기사용에 따른 재질열화에 의한 파괴 인성치의 변화 상태를 검토해 보고, 이를 응용한 수명예측 즉, 3차원 표면 균열을 갖 인 판이 열화된 경우와 건전한 경우를 가정하여 피로 파괴 과정중 파단 특성에 어떤 차이가 일어날까에 대해 연구 검토해 보았다.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2002년도 추계학술대회 논문집
• /
• pp.373-378
• /
• 2002

Metal matrix composites have a great interest in recent years because high specific strength, high specific stiffness characteristics, and application ranges of the composites are extend to variety industry. In this paper, an investigation was performed on the plane strain fracture toughness and slinding wear properties of AC4CH alloy(Al-Si-Mg line) reinforced with 20wt% aluminum borate whisker expect one, which contained a inorganic binder($TiO_2$). the binder led to the formation of strengthen the whisker each other. The test of fracture toughness was using CT(half size) specimen of thickness 12.5mm, width 25mm. and test of slinding wear of using tribo a pin-on-disk machine and lubricant is used without paraffine 8.2CST at room temperature. As results, Fracture toughness $K_{IC}$ is $8.7MPa-m^{05}$ for ABOw/AC4CH, $9.28MPa-m^{05}$ for ABOw/AC4CH added $TiO_2$. but AC4CH alloy was violated the critical stipulated by ASTM standard for valid measurement of $K_{IC}$. In case of, it was performed $J_{IC}$ test instead of $K_{IC}$ based on ASTM E 1820.

• 수산해양기술연구
• /
• 제24권2호
• /
• pp.83-93
• /
• 1988

본 연구에서는 J 적분을 이용하여 두께의 변화에 따른 파괴인성치의 거동을 검토하기 위하여 두께 25mm의 일반구조용 압연강판을 평면가공하여 두께 5, 10, 15, 20, 25mm의 CT 시험편을 제작하였다. 이때 크랙비는 z=0.60인 상태에서 두께를 변화시켜가면서 파괴인성수 J 하(C)와 열단계수 T의 거동을 고찰하였다. 얻어진 결과를 요약하면 다음과 같다. 1) 평면응력 파괴인성치 J 하(C)는 각각의 두께에 대하여 Merkle식에 의한 결과가 가장 높게 나타나고 Rice식, Simpson식, Yoon식의 순서로 나타난다. 2) 평면응력 파괴인성치 J 하(C)는 동일한 J 적분식을 적용하였을 때 두께가 감소함에 따라 증가하였다가 두께 15mm를 기준으로 다시 감소한다. 3) Yoon식을 사용할 경우 평면응력 파괴인성치 J 하(C)와 시험편 두께 B의 상관관계를 무차원화시켜 다음과 같은 실험식을 얻었다. J 하(C)/J 하(IC)=1.7-15.1(B/W)+112.9(B/W) 상(2) -301.3(B/W) 상(3) +260.6(B/W) 상(4) R=0.999 4) 열단계수 T는 각각의 두께에 대하여 Merkle식에 의한 결과가 가장 높게 나타나며, Rice식, Simpson식, Yoon식에 의한 결과의 순으로 나타난다. 5) 열단계수 T는 각각의 단면의 두께에 대하여 동일한 J 적분식을 적용하였을 때 두께의 변화에 따라 거의 일정한 값을 나타내며, 이에 많은 대한 연구 검토가 요망된다