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사형주조한 마그네슘합금 주물의 기계적 성질에 미치는 주조조건의 영향에 관한 연구
한윤성,천병욱,김홍범,최창옥 ( Yun Sung Han,Byung Wook Cheon,Hong Bum Kim,Chang Ock Choi ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.1
N/A The effects of casting conditions on the mechanical properties of sand cast magnesium alloy have been investigated by using various fluxes and pouring temperatures. The magnesium alloy castings has been performed : 1) magnesium alloy melt treated with flux 1 or 2 has been poured into the sand mold mixed with flux 3, at 700 or 750℃ and 2) magnesium alloy melt treated with flux 1 or 2 has been superheated at 900℃ for 15 minutes and cooled down to 700 or 750℃, followed by being poured into the sand mold with flux 3. The magnesium alloy castings at 700℃ shows a clean surface compared to that castings at 750℃, and moreover, the use of flux 3 prevented the oxidation and burning of the castings surface. The magnesium alloy castings at 750℃ contains more oxides around the grain boundries and more micro-shrinkage around the primary α-Mg dendrite compared to the magnesium alloy castings at 700℃. Grain boundaries were more fine in case of superheat treatment to 900℃. Also T4-treated magnesium alloy after superheating showed fine secondary dendrite arm spacing. The highest tensile strength, yield strength, elongation and hardness were shown in cast of pouring 700℃ following addition of flux 1 and 3, after superheating to 900℃, and these values were increased when T4 heat treatment was conducted as well.
고 Mn 강 주강품의 내마모성에 미치는 Ni 첨가의 영향에 관한 연구
이영훈,천병욱,김성한,최창옥 ( Young Hun Lee,Byung Wook Cheon,Sung Han Kim,Chang Ock Choi ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.2
N/A This study has been performed in increase the wear resistance characteristic and the mechanical properties of high Mn steel castings with an addition of Ni to 1∼4% range. The initial structure of plastic cememtite has been possible to transform perfect austenite with watertoughening treatment. Increasing Ni content, the most wear loss has shown that ore has crushed until 100㎏ and decreased with increasing ore amount at ascast, the similar tendency has shown at heat treatment. Chang of hardness has shown high values that ore has been crushed until 300㎏, both as cast and treatment added 2%Ni.
오스템퍼드구상흑연주철의 잔류오스테나이트 조직에 미치는 합금원소 및 열처리온도의 영향에 관한 연구
김덕률,천병욱,김창규,최창옥 ( Deog Ryul Kim,Byung Wook Cheon,Chang Gue Kim,Chang Ock Choi ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.1
N/A Retained austenite in matrix of austempered ductile iron has been well-known as a parameter in controlling mechanical properties, but investigation to obtain quantitative relationship with mechanical properties lack. Therefore, this study executed austempering treatment at various temperatures on ductile iron alloyed with Mo, Ni, Cu. In consequence, microstructure of retained austenite transformed coarse, and quantity increased according as austempering temperature increased. After heat-treatment, microstructure of specimen alloyed with Ni was fine, and toughness improved. At austempering temperature up to 400℃, carbide precipitation started in retained austenite. In consequence, afforded cause of hardness increase, a lot of increase did not arise for coarse structure.
AC4C 합금의 기계적 성질에 미치는 주조조건과 열처리의 영향에 관한 연구
강효경,천병욱,최창옥 ( Hyo Gyoung Kang,Byung Wook Cheon,Chang Ock Choi ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.5
N/A AC4C alloy casts in the metallic mold, zircon sand mold, silica sand mold and shell mold with the pouring temperatures of 680, 710 and 740℃ have been investigated. The tensile strength, elongation and hardness of AC4C alloy castings have been influenced by the kind of molds used. The mechanical properties in zircon sand mold castings were greater than those in other sand mold castings, but were inferior to the properties in metallic mold castings. Eutectic Si particle size and DAS were increased in the order of metallic mold, ziron sand mold, silica sand mold and shell mold. Also, they were increased with the increase of pouring temperatures. DAS, eutectic Si particle size and grain size decreased with the increase of mechanical properties as the cooling rate increased. The eutectic Si particle size and DAS of AC4C alloy castings after T6 treatment were decreased in as-cast. The variation of eutectic Si particle size has been effected on the tensile strength, elongation and fractured surface.
금형주조한 Al-10%Si 합금의 응고조직과 기계적 성질에 미치는 금형의 냉각효과에 관한 연구
이동윤,천병욱,최창옥 ( Dong Youn Lee,Byung Wook Cheon,Chang Ock Choi ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.2
N/A This study has been focused on the influence of the metallic mold cooling effects on the solidification structures and the mechanical properties for Al-10%Si alloy castings by the variation of pouring temperatures, metallic mold temperatures and Cooling part of metallic mold. The dendrite arm spacing of Al-10%Si alloy was decreased with increasing cooling rate. In case of bottom cooling of metallic mold, DAS was appeared to be 20-22㎛ and in the middle cooling, it was increased to 36-40㎛. The DAS decreased proportionally with(cooling rate)^(-3/2) at pouring temperatures 680℃ and (cooling rate)^(-½) at pouring temperature 760℃, but it was proportionally increased to(local solidification time)^(½-⅓) at pouring temperature 680℃ and 760℃. The maximum tensile strength of Al-10%Si alloy casting was obtained in case of bottom cooling of mold at pouring temperature 680℃ and metallic mold temperature 320℃.
생형사의 성질에 미치는 유기 점결제 중자사의 영향에 관한 연구
문재숙,천병욱,김종철,최창옥 ( Jae Sook Moon,Byung Wook Cheon,Jong Cheol Kim,Chang Ock Choi ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.2
N/A This study has been carried out to investigate the properties of green sand as system sand containing various organic core sand, such as Shell core, Cold Box core and Pep Set core sand. The permeability of the system sand containing Pep Set core sand was decreased, but increased from containing 5wt.% core sand. The compressive strength and the surface stability index were increased up to containing 5wt.% core sand, but decreased with containing more than 5wt.% core sand. The compactability index was increased with the ratio of core sands. In case of the system sand containing Cold Box core sand, the permeability and the compressive strength were increased with the ratio of core sands, and the surface stability index and the compactability index was a little increased with the ratio of core sands. In case of the system sand containing Shell core sand, the permeability and the compressive strength were a little decreased with the ratio of core sands, and the surface stability index and the compactability index was a little increased with the ratio of core sands. The bonded force of the system sand mixed with core sands were poor and the grain surface was rough. The loss of ignition of system sand containing shell core sand were more than it with others, it has been found that the system sands containing organic core sands have to reclaim for using molding sand. (Received December 31, 1997)
오스템퍼링 처리한 C/V 흑연 주철의 마모에 미치는 잔류 오스테나이트량의 영향에 관한 연구
주도재,김홍범,천병욱,최창옥 ( Do Jae Joo,Hong Beom Kim,Byung Wook Cheon,Chang Ock Choi ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.4
N/A C/V graphite iron has superior tensile strength, toughness and ductility than grey iron, and better castability than ductile iron. The retained austenite content of C/V graphite iron by austempering treatment affects on the mechanical properties such as ductility, hardness, wear properties and machinability. C/V graphite iron alloyed with Cu and Mo were carried out on the austenitizing at 900˚C for 1 hour, and the austempering at 240∼400˚C for 1 hr. And then the mechanical and wear properties of austempered C/V graphite iron have been investigated by the retained austenite content. In consequence, the retained austenite content was found to be 18.2% in austempering temperature at 240˚C, and was increased 39.2% at 400˚C. Tensile strength and hardness of austempered C/V graphite iron were decreased as the retained austenite content increased, but elongation was increased. The rolling wear loss were increased as the retained austenite content increased. The wear surface of as-cast became to be rough. The microstructure of austempered C/V graphite iron was became to be acicular ausferrite in austempering at 240˚C, and feathery ausferrite at 400˚C. (Received December 31, 1997)
구상흑연주철의 내마모성에 미치는 Sb 및 Sn 의 영향에 관한 연구
권영훈,김창규,김복석,김성한,천병욱,최창옥 ( Young Hoon Kwon,Chang Gyu Kim,Buk Suk Kim,Sung Han Kim,Byung Wook Cheon,Chang Ock Choi ) 한국주조공학회 1991 한국주조공학회지 Vol.11 No.6
N/A The effect of 0.01∼0.10% Sb and Sn on the wear resistance of ductile cast iron was investigated. The hardness was increased with Sb to 0.10%, but the elongation and the impact value were decreased. The tensile strength was increased with up to 0.05% Sb, however decreased with 0.05%∼0.10% Sb. The hardness and the tensile strength were increased and the elongation was decreased with up to 0.10% Sn. The nodularity of graphite was decreased with above 0.08% Sb however Sn had no effect on that. When the maximum compressive stress was low (42㎏.f/㎟), the weigth loss was decreased with increased hardness and when that was high (54㎏.f/㎟ and 65㎏.f/㎟), the weight loss did not depend upon the hardness. The pearlite stabilization with Sb and Sn increased with the wear resistance of ductile cast iron.
부산 , 경남지역 주강 공장의 CO2 주형 고사의 발생실태와 재생에 관한 연구
최준오(Jun Oh Choi),김민섭(Min Seop Kim),최인석(In Seok Choi),천병욱(Byung Wook Cheon),최창옥(Chang Ock Choi) 한국주조공학회 2002 한국주조공학회지 Vol.22 No.3
N/A According to the investigation of waste CO_2 molding sand in the 15 steel foundries in Busan and Gyeong area, about 1 ton of waste CO_2 molding sand per ton of steel castings production was produced In order to reduce amount of Na_2O, Loss of Boiling (L.O.B), Loss of Ignition (L.O.I), Conductivity and PH which are present in the waste CO_2 molding sand below the reclamation effect, more than 50% of elimination for reclamation was required. It was found that the waste CO_2 molding sand does not contain a harmful component designated by industrial waste materials. Reclamation of the waste CO_2 molding sand was practically achieved by an abrasive-dry reclamation process. According to bench time of the sodium silicate-bonded CO_2 molding sand, reduction of compressive strength and surface stability index(S.S.I) become slowdown. Therefore, the reclaimed sand could be allowed the reuse of molding sand in CO_2 molding process including core sand.