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Dive into the research topics where Si-Young Chang is active.

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Featured researches published by Si-Young Chang.


Journal of Alloys and Compounds | 2003

Effect of ECAP on microstructure and mechanical properties of a commercial 6061 Al alloy produced by powder metallurgy

Si-Young Chang; Ki-Seung Lee; Seung-Hoe Choi; Dong Hyuk Shin

Abstract The 6061 (Al–1.01 wt% Mg–1.07 wt% Si) Al alloy was fabricated by powder metallurgy, and then subjected to equal channel angular pressing. The microstructure and mechanical properties such as microhardness and tensile properties of the equal channel angular pressed P/M 6061 Al alloy were investigated. The P/M 6061 Al alloy had an initial grain size of approximately 20 μm. After two pressings at 373 K using route A, the sample revealed microstructure of subgrain bands with a length of ∼0.8 μm and a width of ∼0.3 μm. The subgrain bands became larger above 1 μm in length and width after two pressings at 573 K. An equiaxed ultra-fine grained structure with the mean grain size of ∼0.5 μm was obtained after four repetitive equal channel angular pressings at 473 K using route A and C. The microhardness of P/M 6061 Al alloys was drastically increased from about 40 to 80 Hv by two repetitive pressings at 373 K. However, the microhardness decreased with increasing the pressing temperature. The tensile strength of 6061Al alloy before the equal channel angular pressing was 95 MPa, whereas it increased to both 248 MPa after two pressings at 373 K and 130 MPa after four pressings at 473 K, which was superior to that of a commercial 6061-O Al alloy.


Metals and Materials | 1998

Semi-solid squeeze casting of ignition-proof mg-ca-zr system alloys

Si-Young Chang; Jung-Chul Choi

The production method of the near-net shape molded Mg-Ca-Zr alloys by the devised semi-solid squeeze casting was established and the fabrication factors for sound products were also investigated. The Mg-Ca-Zr alloys having an ignition-proof property and very fine spherical structure provide high production safety and good fluidity for quality near-net shape products in semi-solid state processing. The orifice with a diameter of 30 mm and a plunger speed of 80 mm/s contribute successfully to infiltrate the semi-solid state prema-terial into the designed mold perfectly within the limited infiltration time. The tensile strengths and elongations of the ignition-proof Mg-Ca-Zr and Mg-Zn-Ca-Zr alloys are improved by applying the high pressure of 100 MPa, indicating that pressure more than 100 MPa is also an important fabrication factor.


Metals and Materials | 1998

The effect of thermal cycling on the mechanical properties of sic whisker reinforced magnesium alloy-based composites

Si-Young Chang; Akihiko Kamio

The effect of thermal cyclings on mechanical properties at room and some elevated temperatures of SiC whisker-reinforced magnesium-matrix composites produced by squeeze casting and hot extrusion are clarified. Subsequent thermal cycling produces internal stress at the matrix/SiC whisker interfaces causing fatigue. The mechanical properties of composites are more influenced by the low thermal cycling of 298 K— 77 K than the high thermal cycling 673 K—298 K. The high thermal cycling of 673 K—298 K has only a slight affect on such mechanical properties as tensile strength and proof stress at temperatures lower than 473 K. However, at 473 K and 573 K, the thermal cyclings there almost no influence on the mechanical properties of SiC whisker reinforced AE42 alloy-matrix composites.


Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science | 2002

Low-temperature superplastic behavior of a submicrometer-grained 5083 Al alloy fabricated by severe plastic deformation

Kyung-Tae Park; Duck-Young Hwang; Si-Young Chang; Dong Hyuk Shin


Materials Transactions | 2004

Improvement of Mechanical Characteristics in Severely Plastic deformed Mg Alloys

Si-Young Chang; Sang-Woong Lee; Kae Myung Kang; Shigeharu Kamado; Yo Kojima


Journal of Alloys and Compounds | 2005

Tensile deformation characteristics of a nano-structured 5083 Al alloy

Si-Young Chang; Byong-Du Ahn; Sung-Kil Hong; Shigeharu Kamado; Yo Kojima; Dong Hyuk Shin


Materials Transactions Jim | 1997

Mechanical properties and structure of ignition-proof Mg-Ca-Zr alloys produced by squeeze casting

Si-Young Chang; Hiroyasu Tezuka; Akihiko Kamio


Materials Transactions | 1997

Mechanical Properties and Fracture Process of SiC w /Mg Composites Produced by Squeeze Casting and Extrusion

Si-Young Chang; Hiroyasu Tezuka; Akihiko Kamio


Materials Transactions | 2002

Effect of equal channel angular pressing on the distribution of reinforcements in the discontinuous metal matrix composites

Si-Young Chang; Ki-Seung Lee; Seung Kyun Ryu; Kyung-Tae Park; Dong Hyuk Shin


International Journal of Cast Metals Research | 1998

Ignition prevention of magnesium by simultaneous addition of calcium and zirconium

Si-Young Chang; Muneo Matsushita; Hiroyasu Tezuka; Akihiko Kamio

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Akihiko Kamio

Tokyo Institute of Technology

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Hiroyasu Tezuka

Tokyo Institute of Technology

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Kyung-Tae Park

Hanbat National University

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Shigeharu Kamado

Nagaoka University of Technology

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Yo Kojima

Nagaoka University of Technology

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Atsushi Fukatsu

Tokyo Institute of Technology

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Sung-Kil Hong

Tokyo Institute of Technology

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