수평식 연속주조법에 의한 순 Al 및 Al-5wt%Si 합금 주괴제조시 주조변수에 관한 고찰

김상동,조형호,김명한 ( Sang Dong Kim,Hyung Ho Jo,Myung Han Kim ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.6

N/A The effect of casting variables for making pure Al and Al-5wt%Si alloy rods free from any surface and inside defects was studied by adopting the horizontal continuous casting method with heated mold. The rods were cast under the casting conditions such as the mold temperature of 670∼690℃, water flow rate of 0.2∼0.6ℓ/min, and rod diameter of 4∼8㎜, when the melt temperature and mold to cooler distance was fixed at 700℃ and 20㎜, respectively. The results represented that the casting speed for good quality rod increased as the water flow rate increased, whereas, the casting speed decreased as the rod diameter or mold temperature increased. The statistical analysis of 2³factorial design was also applied and the results represented that the averaged optimum casting speed for pure Al(302㎜/min) was higher than that of Al-5wt%Si alloy(273㎜/min) resulting from the difference of superheat applied. The effect of rod diameter on the optimum casting speed was the highest for pure Al as well as Al-5wt%Si alloy. The effect of water flow rate and mold temperature on the optimum casting speed was in decreasing order.

연속주조법에 의한 Sn-38%Pb 공정합금의 초소성특성

송태석,조형호,최재하,지태구,김명한 ( Tae Seok Song,Hyung Ho Jo,Jae Ha Choi,Tae Gu Ji,Myung Han Kim ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.3

N/A The 8㎜ dia: Sn-38%Pb eutectic alloy rods were produced by use of the horizontal continuous casting process with the heated mold and chill cast process. The cast rods were rolled into 2.0∼0.5㎜ thick plates and structural and mechanical properties were examined. The results revealed that the plates produced by the continuous casting process with the heated mold show much higher superplasticity at ambient temperature (1550% elongation at 0.5㎜ thick plate and 0.5㎜/min strain rate) than the plates procured by chill cast process (630% elongation). Such a high superplasticity of the continuous cast plates is due to the high-quality plates free from any inside and surface defects with fine and uniform distribution of eutectic phases.

수평식 연속주조법에 제조된 무산소동의 방향성 응고에 관한 연구

김명한,이유재,조형호 ( Myung Han Kim,You Jae Lee,Hyung Ho Jo ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.6

N/A The horizontal continuous casting process with the heated mold was applied to obtain the unidirectionally solidified rods(4∼8㎜ dia.) of pure copper with good surface quality. The results could be summarized as follows. 1. The unidirectional solidification of pure copper rods with good surface(mirror surface) quality could be obtained by placing the S/L interface inside the heated mold cavity even though the cast copper rods were covered with thin copper oxide layer. 2. The casting speed for 4mm dia. rods with mirror surfaces was affected significantly by the mold-cooler distance rather than the cooling flow rate when other casting conditions were fixed. 3. The casting speed was the main factor affecting the oxidation of copper during the continuous casting and the thickness of copper oxide layer decreased almost linearly as the casting speed increased.

연속주조법에 의한 Al-11.3wt%Si 합금의 미세조직 변화에 미치는 Ti 및 Sr 의 영향

정찬회,김명한,조형호 ( Chan Hoi Jung,Myung Han Kim,Hyung Ho Jo ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.5

N/A The horizontal continuous casting process with the heated mold has been applied to study the effect of grain refiner or modifier such as Ti or Sr, respectively, in Al-11.3wt%Si alloy. The results represented that the addition of 0.02%Sr or 0.2∼0.4%Ti promoted the directionality of primary α dendrite, whereas the addition of 0.6%Ti suppressed the directionality. Also, the addition of 0.02%Sr suppressed the occurrence of feathery grains, while the addition of 0.2%Ti promoted the occurrence of feathery grain. The addition of Ti over 0.4% suppressed the occurrence of feathery grain, resulting from the in creasing grain-refining effect. The addition of Ti also increased the coarsening effect of eutectic silicon phase in Al-11.3%Si alloy.

Squeeze Casting 에 의한 Al-SiCp 복합재료의 제조에 있어서 가압력의 영향

문정탁,김명한,조형호 ( Jeong Tak Moon,Myung Han Kim,Hyung Ho Jo ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.1

N/A The Al-SiC_p composite was fabricated by the liquid mixing and squeeze casting method. The effects of squeezing pressure in the fabrication of the Al-SiC_p composite were studied by analysing microstructure and mechanical properties. The results could be summarized as follows; 1) The tensile strength and hardness of Al-SiC_p composite were increased as the squeezing pressure was increased. However, the elongation and amount of wear were decreased as the squeezing pressure was increased. 2) When the high squeezing pressure at the high molten temperature was applied in fabrication, the mechanical properties of Al-SiC_p composite were declined, which resulted from the deterioration of SiC_p particles in the matrix alloy. 3) The wear mechanism at the matrix alloy only was changed from adhesive wear to oxidation wear and from oxidation wear to fusion wear. However, the Al-SiC_p composite represented sliding wear mechanism resulting from the sliding action of SiC_p particles in the matrix alloy.

가열주형 연속주조시 발생되는 줄무늬 결함에 관한 연구

안기성,송태석,지태구,조형호,김명한 ( Ki Sung An,Tae Seck Song,Tae Gu Ji,Hyung Ho Jo,Myung Han Kim ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.2

N/A The striations parallel to the casting direction are the characteristic defects occurring during the unidirectional solidification of nonferrous metals such as pure Al and Sn. It has been known that the defects affect the recrystallization temperature as well as the mechanical and electrical properties of Al. However, it has not been still known about the effect of casting factors such as the casting speed, rod diameter of cast metals, and alloying elements on the occurrence of striations. In the present study, these casting factors affecting the occurrence of striation were investigated by adopting the quantitative examination of striations. Also, the relation between striation defects and feathery grain, which are very similar to the striation defects, was studied.

가열주형식 연속주조법에 의한 Al-Si 합금의 응고조직에 관한 연구

김원태,문정탁,김명한,조형호 ( Won Tae Kim,Jeong Tak Moon,Myung Han Kim,Hyung Ho Jo ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.5

N/A The horizontal continuous casting method with the heated mold was applied to study the solidification structures of the pure Al and Al-0.5wt%Si and Al-1.0wt%Si alloy rods. The results could be summarized as follows: 1. The S/L interface structures of pure Al represented the hexagonal cells at the casting speed of 590 and 350㎜/min, respectively. However, the hexagonal cells became irregular as the casting speed and(or) Si amount increased. 2. The striation increased as the Si amount and casting speed increased and was found to result from the occurrence of growth twin crystals by XRD analysis. 3. The striation did not affect the mechanical and electrical property of the drawn wire from the casted rod. This means the striation is not a serious defect which has to consider in the production of micro-sized fine wire in the drawing process.

Sn-Zn합금의 주조조건과 응고특성

송태석 ( Tae Seok Song ),김명한 ( Myung Han Kim ),조형호 ( Hyung Ho Jo ),지태구 ( Tae Gu Ji ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.6

3000계 알루미늄 합금에서 형성되는 금속간화합물과 압출성에 미치는 Mn의 영향

金明漢,曺亨鎬,李甲鎬 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.8

The effect of Mn contents in 3000 aluminum alloys on formation of intermetallic compounds and extrusion pressure was investigated. The eutectic intermetallic compounds α-Al(Fe, Mn) Si were precipitated when Mn was added in the range of 0.3-1.5 wt.% in 3000 aluminum alloys. The concentration of Mn in the eutectic intermetallic compounds was increased with the increase of Mn addition. Also, the primary intermetallic compound of Al_6(Fe, Mn), which Mn atoms were replaced completely by Si atoms, was precipitated in the addition of 1.5 wt.% Mn. The TEM analysis represents that the eutectic intermetallic compounds have bee structures and primary intermetallic compounds has rhombohedral structure. The amounts of intermetallic compounds were increased with the amounts of precipitated compounds, resulting in the increase of yield stress as well as extrusion pressure.

A7003 합금의 환경친화적 압출공정을 위한 Mg조성 및 공정비교 연구

조훈,조형호,한명근,김영직 한국전과정평가학회 2002 한국전과정평가학회지 Vol.4 No.1

최근 수송기계 경량화 추세에 부응하여 door impact beam, seat side rail 및 hood support와 같은 자동차 부품등에 Al-Mg-Zn계 중경질 A7003 합금소재의 적용이 검토되고 있는 실정이다. 그러나 이들 합금소재의 적용을 위해서는 제품의 용도와 특성을 만족함과 동시에 압출성이 높은 합금소재의 개발이 선행되어야 한다. 본 연구에서는 A7003 합금소재의 압출성을 향상시키기 위하여 합금원소 첨가량이 미세조직, 압출성 및 기계적 특성에 미치는 영향을 조사하였다. Mg조성 제어에 의해 기계적 강도의 저하없이 A7003 합금의 압출성을 향상시킬 수 있었다. 또한 MLCA 기법을 적용하여 A7003 합금중의 Mg 첨가량 및 빌렛가열공정 변화에 따른 에너지 소비량 및 환경오염부하물질 배출량을 산정하였다. A7003 합금중 Mg의 첨가량을 제어하여도 압출재 생산에 소요되는 에너지의 소비량은 거의 같음을 확인하였으며 CO₂와 같은 대기오염물질을 저감시키기 위해서는 유도가열에 의한 빌렛가열공정의 적용이 가장 효과적임을 알 수 있었다. A7003 alloy has characteristics of their excellent weldability, high corrosion resistance and superior plastic working however the broadening of application for the alloy has been hampered by the lower extrudability associated by Mg content. For improvement of extrudability and enhanced recovery efficiency during Al scrap recycling, it has been generally practiced to reduce Mg content in A7003 alloy. Therefore, it is necessary to investigate the influence of Mg content on mechanical strength and extrudability of A7003 alloy. For efficient material processing which has small amounts, material life cycle assessment(MLCA) is evaluated. The quantitative analysis of energy requirements and CO₂ emission for production of A7003 extruded bar are estimated with different Mg content and billet pre-heating process (heating source by light oil or LPG). In particular, the estimation of energy requirements was performed within shipping and gating range (except the mining and extraction stages) to investigate the influence of the variables on energy requirements and CO₂ emission in detail. As Mg content increased, the flow stress and the extrusion pressure for A7003 alloy increased. It has been thought that an increment in extrusion pressure with increasing Mg content is caused by the solid solution hardening of Mg atoms in the matrix and increment in volume fraction of intermetallic compound, Mg2Si. The extrudability and the tensile strength are equal to, or above that of conventional A7003 alloy even the content of Mg varied from 1.1wt.% to 0.5wt.%.alloy. This means that minimizing the content of Mg in A7003 alloy can enhance recovery efficiency during Al scrap recycling. It can be quoted that rather than Mg content energy source for billet heating is a prime factor to determine the atmospheric CO₂ emission.