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논문 : 수치해석 ; 원형빌렛 DC주조몰드에서 이동자장에 의한 자기장, 유동장 및 온도장의 수치해석
정순효 ( S. H. Chung ),조영환 ( Y. W. Cho ),심재동 ( J. D. Shim ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
The electromagnetic stirring of molten metal in the continuous casting mold is one of the most effective tools to decrease various casting defects such as macrosegregation, center cracks, and to homogenize the grain structure of the ingots. For DC casting of large diameter aluminium billets, it is important to control molten metal flow and heat transfer in order to prevent the formation of center cracks and macrosegregation. A circular inductor with minimum height producing travelling magnetic field in vertical direction has been designed with the help of a 3D numerical simulation program. The electromagnetic field, fluid and heat flows have been analysed by the numerical calculation and physical model experiment. The results of calculation agreed very well with those of experiment. It has been found that the downward stirring near the mold wall seems more efficient to homogenize the melt than the upward stirring. An optimized inductor design for stirring aluminium melt in the DC casting mold of 240 mm inner diameter have been proposed based on the result of the numerical calculation.
저탄소 2% Mn 강 및 2% Mn-Nb-V 강의 냉간압연후(冷間壓延後)의 시효처리효과 : Ⅱ. Splitting 현상
맹선재,강찬형,현도빈,정순효 대한금속재료학회(대한금속학회) 1982 대한금속·재료학회지 Vol.20 No.10
Splitting behavior of tensile specimens of low carbon 2% Mn steel and 2% Mn-Nb-V steel that had been cold rolled and aging treated were studied. The occurrence of splitting depends on steel composition, degree of cold reduction and aging treatment conditions. The susceptibility to splitting is closely related to the weakness of ferrite grain boundaries This weakness is attributed to elongation of the ferrite grains in the direction of cold rolling and also to precipitation and growth of carbides at the grain boundaries during the aging treatment.
티타늄 용해용 Cold crucible 의 설계 및 용해실험 연구
김경태,조영환,정순효,심재동,오영주 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.4
The design of a laboratory cold crucible for melting titanium and its alloys has been optimized using both the numerical simulation and the physical model experiment with tin. The electromagnetic field and magnetic pressure distribution in the cold crucible were calculated using a three dimensional finite element method. Temperature of the molten tin and titanium was measured under various electric power input and with different melt weight. The shape of the melt free surface, total melt surface area, soft-contacting area, and the Joule heating rate were also calculated. With the help of the heat transfer equation, overall heat transfer coefficient at the interface between the melt and the cold crucible was determined. With changing electric power input, stable and/or unstable melting states have occurred sequentially. Only in the stable melting state, superheating of tin and titanium, about. 70-100 K above the their melting temperatures was achieved. Overall heat transfer coefficient for tin and titanium were estimated as 3500 and 800 V/㎡K, respectively.