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가스배관재의 X-선 회절분석과 피로균열거동에 관한 연구
임만배(MAN-BAE LIM),윤한기(HAN-KI YOON),박원조(WON-JO PARK) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.3
This study investigates a relationship between fracture mechanics parameters (Stress Intensity Factor Range: ΔK, Maximum Stress Intensity Factor: Kmax ) and X-ray parameters (residual stress:or, half-value breadth: B) for SG365 steel at elevated temperature up to 300℃. The fatigue crack propagation test were carried out and X-ray diffraction technique according to the direction of crack length was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase at low ΔK region, to reach a maximum value at a certain value of Kmax or ΔK and then to decrease. Residual stress was independent of stress ratio by arrangement of ΔK and half value breadth were independent of the arrangement of Kmax. The equation of orΔK was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.
임만배(MAN-BAE LIM),윤한기(HAN-KI YOON) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.3
The elastic plastic fracture toughness of this material is evaluated by the an unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the material tearing modulus and characterizes the crack tip field under the plane stress and strain. SG-365 steel is observed that J-R curve and Tmat value decrease as 0%, 20%, 30%, and 40%. The 40% side grooved specimen is very useful in estimation of the J<SUB>IC</SUB>. 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 tunneling and shear lip by the side groove. Applicability of tearing modulus(T<SUB>J</SUB>) proposed by paris et al as instability panameter for this meterial is investigated.
X-선 회절에 의한 피로파면거동과 응력세기계수 예측에 관한 연구
임만배(Man-Bae Lim),부명환(Myung-Hawn Boo),조충형(Chung-Hyung Joh),김영석(Young-Suk Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3
This study investigated the effect of stress intensity factor ranges, or ΔK=Kmax-Kmin on residual stress for SG365 steel. The fatigue crack growth rates of the SG365 steels were determined at RT and 300℃ on the compact tension specimen under the ratio of Pmax and Pmin set at 0.1 and 0.5, respectively. To correlate ΔK and residual stress and the FWHM are measured on the fractured surface of the CT specimens using diffraction lines {211} determined by an X-ray residual stress tester. The Residual stress had no clear trend with ΔK but the FWHM had a nice linear relationship with ΔK. Based on the these results, the predictability of ΔK is discussed as a function of the FWHM and residual stress, if any, determined by X-ray diffraction lines.
임만배(MAN-BAE LIM),차귀준(GEE-JUN CHA),윤한기(HAN-KI YOON),공유식(YU-SIK KONG),김정호(JUNG-HO KIM) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.3
SG-365 steel is an important material and used for manufacturing a pressure vessel which the gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the an unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT 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<SUB>IC</SUB>. 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 tunneling and shear lip by the side groove.
SA 508C-3강의 고온에서 J-R Curve 및 Tmat의 평가
임만배(Man-Bae Lim),차귀준(Gee-Jun Cha) 한국해양공학회 1998 韓國海洋工學會誌 Vol.12 No.3
In this study, the J-Resistance Curve and material tearing modulus of SA508-C3 steel, which is one of the used nuclear pressure vessel steel, are measured at room temperature, 200℃ and 300℃ according to load ratio analysis and ASTM E813, ASTM E1152, respectively. It is observed that J-R curve and Tmat value decrease as the temperature level increase. Applicability of T<SUB>j</SUB> proposed by Paris et al as an instability parameter for ductile material is investigated. It is concluded that results are the T<SUB>j</SUB> parameter may be used as a crack instability parameter.
SA508-3재의 제하컴플라이언스법과 하중비해석을 이용한 파괴저항곡선 평가
임만배(Man-Bae Lim),차귀준(Gee-Jun Cha),윤한기(Han-Ki Yoon),안원기(Won-Ki An) 한국해양공학회 1998 韓國海洋工學會誌 Vol.12 No.1
The fracture resistance curve is one of most important and design techniques employed in nuclear pressure vessel structures. This study is to evaluate the J-R curve characteristics for the SA508C-3 by the unloading compliance method and load ratio analysis. The effect of strain aging for the exponential correlation of the J-R curve in this metal are investigated at room temperature, 200℃ and 300℃. The load ratio analysis method can evaluate the J-R curve by using the simple tension load-displacement curve only without the repeat of the unloading and loading. Therefore, the analysis by the proposed load ratio method has a merit, in comparison with the unloading compliance method, which can measure the crack length without the precision measurement equipment.
공유식,임만배,이상필,윤한기,오세규,Kong, Yu-Sik,Lim, Man-Bae,Lee, Sang-Pill,Yoon, Han-Ki,Oh, Sae-Kyoo 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.6
The high temperature creep behavior of heat machine systems such as aircraft engines, boilers and turbines in power plants and nuclear reactor components have been considered as an important and needful fact. There are considerable research results available for the design of high temperature tube materials in power plants. However, few studies on the Initial Strain Method (ISM) capable of securing repair, maintenance, cost loss and life loss have been made. In this method, 3 long time prediction Of high temperature creep characteristics can be dramatically induced through a short time experiment. The purpose of present study is to investigate the high temperature creep lift of Udimet 720, SCM 440-STD61 and 1Cr-0.5Mo steel using the ISM. The creep test was performed at 40$0^{\circ}C$ to $700^{\circ}C$ under a pure loading. In the prediction of creep life for each materials, the equation of ISM was superior of Larson-Miller Parameter(LMP). Especially, the long time prediction of creep life was identified to improve the reliability.
알루미늄 합금의 피로강도향상과 피로특성에 미치는 쇼트피닝 영향
전현배(Hyun-Bae Jeon),임만배(Man-Bae Lim),박원조(Won-Jo Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
The purpose of this study is to investigate the effect of shot peening on the fatigue strength and fatigue life of two kinds of aluminum alloys. The fatigue strength behavior of aluminum alloys were estimated by the stress ratio and shot velocities. The fatigue life and strength increased with increasing the test shot velocity. However, at the shot velocity range between 50㎧ and 70㎧, the compressive residual stress phenomena were observed in test conditions of different shot velocity. The optimal shot velocity is acquired by considering the peak values of the compressive residual stress, dislocations, brittle striation, slip, and fisheye on the fracture surface of test specimen. It was observed from the SEM observation on the deformed specimen that the brittle striation, fisheye were showed in the intergranular fracture structure boundaries at the this velocities. Therefore, fatigue strength and fatigue life would be considered that shot velocity has close relationship with the compressive residual stress.