• 한국압력기기공학회 논문집
• /
• 제14권1호
• /
• pp.1-7
• /
• 2018

Materials in nuclear power plants can be embrittled by neutron irradiation. According to existing studies, the effect of the material property by irradiation embrittlement can be approximately simulated by cold working (pre-strain). In this study, finite element damage analysis method using the stress-modified fracture strain model is proposed to predict J-Resistance curves of irradiated SUS316 stainless steel. Experimental data of pre-strained SUS316 stainless steel material are obtained from literature and the damage model is determined by simulating the tensile and fracture toughness tests. In order to consider damage caused by the pre-strain, a pre-strain constant is newly introduced. Experimental J-Resistance curves for various degrees of pre-strain are well predicted.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.78-83
• /
• 2003

The aim of this study is to investigate the effect of hydrogen embrittlement od Zr-2.5Nb CANDU pressure tube. The test were performed at three hydrogen contents for transverse tensile and CCT specimens while the test temperatures were changed (RT to 300$^{\circ}C$). The specimens were directly machined from the tube retaining original curvature using electric discharge machine. Both the transverse tensile and the fracture toughness tests showed the hydrogen embrittlement clearly at RT but this phenomenon was disappeared while the test temperature arrived over 250$^{\circ}C$. From the fracture toughness test, it was found that fracture toughness dJ/da was increased up to 200$^{\circ}C$ and then decreased.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.131-136
• /
• 2003

CF8M cast austenitic stainless steel is used for several components such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. In this study, three kinds of the aged CF8M specimen were prepared using an artificially simulated aging method. The objective of this study is to summarize the method of estimating ferrite contents, Charpy impact energy and J-R curve, and to evaluate the thermal embrittlement of the CF8M cast austenitic stainless steel piping used in the domestic nuclear power plants.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1174-1179
• /
• 2003

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. This study shows that ferrite content can be predicted by use of the artificial neural network. The neural network has trained learning data of chemical components and ferrite contents using backpropagation learning process. The predicted results of the ferrite content using trained neural network are in good agreement with experimental ones.

• Journal of Welding and Joining
• /
• 제8권3호
• /
• pp.39-52
• /
• 1990

The research is to insure the soundness of the stainless steel overlaid weld metal(21/4Cr-IMo steel + SUS 309L) for a pressure vessel application. Detail studies were conducted for the PWHT influence on the micrstructure and intergranular corrosion characteristics of the overlaid weld metal as well as initiation of hydrogen embrittlement crack(or Disbonding) when welded metal are exposed to the hydrogen atmosphere. Hydrogen was experimentally charged to the overlaid weld metal in order to study PWHT effect on the susceptibility of hydrogen embrittlement crack. The results of this research are as follows: 1. At the bond region, austenite grain of the stainless steel side became coarsed and Cr23C6 type carbide was precipitated at the coarsed austenitic grain boundaries. Intergranular Corrosion width(by Straiss test) increased with increasing PWHT temperature and PWHT time.

• 비파괴검사학회지
• /
• 제19권2호
• /
• pp.129-144
• /
• 1999

플랜트와 같은 장치산업은 내구성 구조물이므로 사용중에 열화가 발생하는 것은 필연적이다. 특히 고온, 고압의 부식환경하에서 사용되는 설비는 손상이 심하므로 가동중에 돌발적인 고장이 발생하여 플랜트의 가동을 중지하거나 파손사고가 일어나 생산손실은 물론 경우에 따라서는 안전사고의 발생, 환경오염 등 사회적인 문제를 일으키므로 이들 설비의 경년열화 실체를 충분히 이해하고 대책을 수립하는 것은 대단히 중요하다. 따라서 본고에서는 장치산업에서 발생하는 열화현상(재료의 연화, 경화 및 취화, 크리프, 피로, 부식, 마모 등)중 손상의 주류를 이루는 연화, 경화 및 취화, 크리프 피로에 대하여 기본적인 손상기구(damage mechanism)와 비파괴적 진단 및 평가 방법에 주안점을 두어, 현재 국내의 각종 플랜트 진단에 실용화된 기술을 해설하여 이 분야에 종사하는 관계자 여러분의 이해에 조금이라도 기여코자 한다.

• Journal of Welding and Joining
• /
• 제3권2호
• /
• pp.35-41
• /
• 1985

The fracture toughness of subcritical HAZ in the hot strained weldments of two structural steels(SB 41 and SA 537) has been investigated by COD test method and metallurgical study. The obtained results are summarized as follows; 1. The hot straining embitterment of subcritical HAZ depends on the hot straining amounts of notch tip, and the transition temperature( $T_{tr}$ ) increases with the accumulated hot straining amounts(.SIGMA. vertical bar .delta.$_{t}$vertical bar). 2. The fracture toughness of subcritical HAZ depends on materials and microstructure. The transition temperature( $T_{tr}$ ) of subcritical HAZ in SB 41 is almost same as that of parent material, however in SA 537 the temperature is higher than that of parent and lower than that of transformed HAZ. 3. The subcritical HAZ in SA 537 shows a higher toughness at small amounts of hot straining (.SIGMA. vertical bar .delta. $_{t}$vertical bar<0.3mm).mm).

• 대한기계학회논문집A
• /
• 제28권4호
• /
• pp.460-466
• /
• 2004

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. This study shows that ferrite content can be predicted by use of the artificial neural network. The neural network has trained teaming data of chemical components and ferrite contents using backpropagation learning process. The predicted results of the ferrite content using trained neural network are in good agreement with experimental ones.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1998년도 특별강연 및 추계학술발표 개요집
• /
• pp.292-294
• /
• 1998

• Nuclear Engineering and Technology
• /
• 제20권3호
• /
• pp.203-213
• /
• 1988