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강의 연속주조시 Mold Oscillation에 따른 Flux층 내의 동적 압력변화 해석
박태호 ( Park Tae Ho ),김지훈 ( Kim Ji Hun ),최주 ( Choe Ju ),예병준 ( Ye Byeong Jun ) 한국주조공학회 2004 한국주조공학회지 Vol.24 No.1
N/A The pressure of the mold flux acting on the meniscus shell was investigated through the coupling analysis of heat transfer in the mold and fluid flow in the flux caused by the mold oscillation. Finite element method was employed to solve the conservation equation associated with appropriate boundary conditions. As reported by previous workers. the axial pressure is positive on the negative strip time and negative on the positive strip time. A maximum pressure is predicted toward the top of the meniscus shell which has the thin shell arid a maxirnuni value is in proportion to the relative mold oscillation velocity. The relative mold oscillation velocity was changed by the effect of meniscus level fluctuation. Therefore the pressure of the mold flux acting o n the menisctis shell was different each cycle ofthe mold oscillation due to the irregularity of relative mold oscillation velocity
강의 연속주조시 Mold Oscillation에 따른 Meniscus 초기 응고 해석
박태호 ( Park Tae Ho ),김지훈 ( Kim Ji Hun ),최주 ( Choe Ju ),예병준 ( Ye Byeong Jun ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.6
N/A Numerical models on the formation of oscillation marks have been developed for the decrement of casting surface defects. However it has not yet been reported that the effect of mold oscillation on the solidification of meniscus shell. The present study on the formation of meniscus shell has been conducted by coupling analysis of heat transfer in the mold and fluid flow in the flux caused by the mold oscillation. Finite element method was employed to solve the conservation equation associated with appropriate boundary conditions. Initial solidification started from the curved meniscus and proceeded along the meniscus shape. Solidification of the steel shell at the meniscus was proceeded under the iteration of solidification delay of the shell tip on the positive strip time and rapid solidification on the negative strip time.
연속주조된 강재 슬래브 표면의 Oscillation Mark 형성에 관한 평가
박태호 ( Park Tae Ho ),김지훈 ( Kim Ji Hun ),최주 ( Choe Ju ),예병준 ( Ye Byeong Jun ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.5
N/A In early solidification during the continuous casting of steel slabs, the formation of oscillation marks on the surface of slabs was mainly affected by carbon contents and casting conditions. The control of oscillation mark is required for the HCR(Hot Charged Rolling) process because the deep oscillation marks seriously deteriorate the surface qualities of steel slabs. The metallographic study has revealed that the oscillation mark can be classified principally according to the presence or absence of a small `subsurface hook` and the depth of the oscillation marks in the subsurface structure at the basis of individual oscillation marks. The subsurface hook of oscillation marks was either straight or curved. When the amount of overflow was small and the subsurface hook was formed in the top of oscillation marks, the subsurface hook was straight and the oscillation mark was shallow. The oscillation marks without subsurface hook have small early solidification shell and were formed wide. The actual negative strip time(t_(N)) was changed by the effect of meniscus level fluctuation Therefore irregular early solidification shell and oscillation mark were formed.
최주,이종근,최승주 대한금속재료학회(대한금속학회) 1981 대한금속·재료학회지 Vol.19 No.7
Trials were made to develop gamma prime precipitation hardened nickel-base superalloys which have both excellent creep rupture strength and hot corrosion resistance. The factors which influence high temperature characteristics were expressed a function of alloy composition by means of multiple regression analysis. Setting certain conditions on the factors, alloy composition was calculated with use of the computer. The alloys developed by this method are proved to be excellent in creep rupture strength and sulfidation resistance.