http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Keisaku Ogi (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
서성문,이재현,Hirofumi Miyahara,Keisaku Ogi,김인수,조창용 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.3
The solidification grain structure and texture evolutions during single crystal (SX) casting of the advanced Ni-base superalloy CMSX-4 have been investigated. In order to understand the development of the solidification grain structure, SX casting experiments were carried out with a specially designed grain selector in a Bridgman directional solidification (DS) furnace. In addition to casting trials, the SX casting process was simulated by a 3-D cellular automaton-finite element (CAFE) model. The predicted solidification grain structure and the texture evolutions were validated by comparison with the microstructural observation and the electron back scattered diffraction (EBSD) results. It was shown that the overall grain structure, crystallographic texture evolution, and the location where the final selection of the single crystal occurs can be predicted well by the present CAFE model. The axial texture evolution of the single crystal was found to be significantly influenced by the grain density at the chill surface. The CAFE predictions also revealed that the geometry of the grain selector plays a significant role in the final selection of the single crystal.
-
Influence of Microstructures on Mechanical Properties of Al-Si-Cu-Mg Cast Alloys
Kang, Hyo Gyoung,Choi, Chang Ock,Ogi, Keisaku 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.1
A commercial Al-Si-Cu base alloy (JIS AC4B) and the similar compositions of pure alloys with 0 to 0.7%Fe were solidified at the cooling rate of 2.7 to 14.4K/s. Tensile tests and quantitative microstructure analysis were performed on the as cast specimens and T_6specimens. Tensile strength (бB) increased as the microstructure became finer. бB rose linearly with decreasing of secondary dendrite arm spacing(DAS) of primary α , while the modification of eutectic Si with Sr had a smaller effect. The crack propagated along dendrite arms and the fracture surface exhibited a structure whose coarseness was close to DAS. Fe-rich intermetallic compounds took the acicular and chinese script type shapes. Higher cooling rate and more Sr addition promoted the crystallization of chinese type one. The Fe-rich compounds decreased the elongation, though they tended to raise the yield strength. TEM analysis revealed that the aging process was influenced by eutectic Si and minor elements, however the these phenomena may have little influence on tensile properties.
-
Kang, Hyo-Gyoung,Choi, Chang-Ock,Ogi, Keisaku 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.2
TEM analysis was applied to the investigation on age hardening processes of a commercial JIS ACAB alloy and the similar compositions of pure N-Si-Cu and Al-Si-Cu-Mg cast alloys. A series of alloy specimens were solution treated at 773K for l0hr and subsequently aged at 433K and 473K for l0min to 10⁴min. The typical hardness-aging time relations are obtained on each alloy specimen. The maximum hardness of specimen aged at 433K becomes larger from Hv95 to Hv152 as the Mg content of alloy increases from 0 to 0.43mass%. TEM reveals many dislocations around eutectic Si particles, which should be introduced into aphase during quenching from solution treatment emperature, because of the difference in the thermal expansion coefficient between α-natrix and eutectic Si. The formation of GP Zone is suppressed and the precipitation of θ' is promoted in the ternary 4-Si-Cu alloy, which contains higher density of dislocations. Many tiny particles of Mn-rich compound precipitate in the α matrix of solution-treated. AC4B alloy, which decrease the Cu content of a phase and the age-hardening ability of the alloy.
-
Kang, Hyo-Gyoung,Choi, Chang-Ock,Ogi, Keisaku 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.2
The effects of cooling rate and additions of Sr and Ti-B on microstructural features such as grain size, dendrite arm spacing, morphologies of eutectic silicon and iron rich compound were investigated for the Al-6.55%Si-2.78% Cu-0.59%Fe-0.38%Mg-0.34%Mn alloy of ACAB type. This alloy solidified in the order of primary α, a+a-AlFeMnSi compound eutectic, α+Sieutectic, α+β-AlFeMnSi. a +Si+Mg₂Si and α+Si+Al₂Cu eutectic. The grain size, dendrite arm spacing, the size of eutectic silicon particles and the length of needle like β-AlFeMnSi decreased with increasing the cooling rate, and they were in linear relations on logarithmic scales. Addition of small amount of Ti-B remarkably refined grain size while it practically unaffected the other solidification structures At the cooling rate of 2.73K/s, 14.38K/s and 108.08K/s, the eutectic silicon crystals fully modified by adding Sr more than 60ppm, 20ppm and 5ppm, respectively. Addition of Sr and higher cooling rate tended to modify the needle like iron rich compounds to Chinese script type one. DSC analysis revealed that the Sr modification was accompanied by the characteristic changes in cooling curve.
-
Seo, Seong-Moon,Kim, In-Soo,Jo, Chang-Yong,Ogi, Keisaku Elsevier 2007 Materials science & engineering. properties, micro Vol.449 No.-
<P><B>Abstract</B></P><P>A three-dimensional cellular automaton (CA) model has been coupled with finite-element (FE) heat flow calculation to predict the solidification grain structures in a Ni-base superalloy. In the present CA–FE model, Gaussian distribution of nucleation sites was adopted and the Kurz–Giovanola–Trivedi model was extended to multi-component alloys to account for the growth kinetics of the dendrite tip. In particular, for describing the Gaussian distribution of nucleation sites at the mold surface, an empirical relationship between the nucleation density at the surface and the initial cooling time of the melt was proposed and applied to the input parameter in the model. The predicted grain structures were validated at various casting conditions by comparison with the experimental micrographs obtained with cylindrical shaped castings. The CA–FE model was also applied to the complex shaped turbine blade casting and the computed grain structure of turbine blade airfoil was compared with the experimental micrograph.</P>
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
