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연속주조압연으로 제조한 Stainless 강판의 조직 및 기계적 성질
조성석 忠南大學校 産業技術硏究所 1986 산업기술연구논문집 Vol.1 No.1
Using the twin-roller type melt-quenching technique the effects of pouring temperatures on the microstructures and mechanical properties of stainless steel have been investigated. The melt-rolled stainless steel strips have the columnar(surface) and equiaxed grains(center) which became finer with increasing pouring temperature. But the hardness of these steels, which is about 295DPN, remains almost unchanged with grain size refinement. Hardness and ultimate tensile strength increased with increasing heat treatment temperature.
Ni基 超合金 Waspaloy의 再結晶에 미치는 初期 r' 크기의 영향(1)
조성석 충남대학교 공업교육연구소 1984 論文集 Vol.7 No.1
The effects of initial r'-size on the recrystallization behaviour of waspaloy have been studied by transmission electron microscopy. The deformed structure of I hour -aged specimen has more homogeneous and fine intersecting slip lines than that of 24 hour-aged specimen. These lead to the increase in sites of nucleation and the growth rate of the recrystallization front. Bypassing of migrating front due to high deformation accelerates the recrystallization of Waspaloy.
급냉응고한 오스테나이트계 스테인레스강의 조직 및 인장 성질에 미치는 조성의 영향
조성석,오명석 대한금속재료학회(대한금속학회) 1987 대한금속·재료학회지 Vol.25 No.12
Using a twin-roller type melt-quenching technique we investigated the effect of chemical composition on the microstructure and tensile properties of austenitic stainless steels. For three austenitic stainless steels, 0.5㎜ thick sheets were produced. For Cr-eq./Ni-eq.< 1.35, solidification typically takes place by primary austenite formation whereas if the ratio is greater than 1.35, primary ferrite formation is the solidification mode. As the Cr-eq./Ni-eq. ratio increases, the cooling rate of melt-quenched austenitic stainless steels slighlly decreases. In a melt-quenched AISI 304 (Cr-eq./Ni-eq. ratio: 1.7), the ferrite to austenite transformation was suppressed, resulting in residual ferrite. Secondary dendrite arm spacing of melt-quenched austenitic stainless steels was about 2-3㎛ . After heat treatment, the tensile properties of the melt-quenched stainless steels are bettor than those of conventional austenitic stainless steels.
조성석,강영곤,김상무 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.9
In this study, aluminum powders were sintered to porous aluminum plate, and the sound absorbing characteristics and mechanical properties was investigated. The difference of thermal expansion coefficient between aluminum and alumina was used in sintering aluminum powder and in order to increase sintering property of aluminum powder, Al-8%Si powder was mixed as a binding material. The cross section of sintered plate was obserbed with optical microscope and EDAX. The result showed that silicon was mainly distributed near the neck between sintered aluminum powders. and Al-8%Si alloy powder worked as a binding material. The result of measurement of sound absorbing coefficient showed resonator type characteristics by increasing the thickness and density of sintered plate and maximum sound absorbing coefficient was transfered to lower frequency by increasing air space of the back side of sound absorbing plate. Tensile strength of the sound absorbing plate was increased to 31∼37㎏/㎠ by increasing density.
알루미늄 6063 기지를 이용한 분말 소결판의 제조와 흡음 기구에 관한 연구
조성석,강영곤,김상무 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.12
Aluminum 6063 and Al-8wt%Si powders were produced by centrifugal atomization and mixing. They were sintered under pressure in N₂ atmosphere to make porous sound absorbing plate. The micromorphology of powder and sintered plate was observed by SEM and optical microscope. It is found that Si is thoroughly dispersed in the matrix (Al 6063 powders) of the plate. For the sound absorbing coefficient measurement, impedance tube method was applied. The relation between sound absorbing coefficient, density of sintered plate, volume and distribution of porosity was investigated. Sound absorbing effect through the influence of binder which leads to the constructive variation of porosity was also investigated.
조성석,구자명,김학동 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.9
The magnetic properties and the structure of high silicon steel sheets (3wt%-6.5wt%Si) prepared by the twin roller-quenching method were investigated. The columnar grains about 5-7㎛ in diameter were observed in the as-prepared sheets and the columnar grains grew from the surface to the center part of the sheet. In the as-prepared sheet, the coercive force was 1.05 Oe for the 6.5 wt%Si-Fe sheet, and the average mag netic iron loss W_(15/50) and W_(10/50) of the sheets having the coercive force of 1.05 Oe was 1.50 W/㎏ and 0.46W/㎏ respectively.