The Experts below are selected from a list of 480 Experts worldwide ranked by ideXlab platform
Sung Soo Park - One of the best experts on this subject based on the ideXlab platform.
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improved corrosion resistance of mg 8sn 1zn 1al alloy subjected to low temperature Indirect Extrusion
Corrosion Science, 2018Co-Authors: Soo-min Baek, Jeong Su Kang, Hyungjoon Shin, Sung Soo ParkAbstract:Abstract We report that the corrosion resistance of Mg–8Sn–1Zn–1Al alloy is significantly improved by the application of a low-temperature Indirect Extrusion process utilizing artificial cooling. It was found that the corrosion rates, measured by immersion tests in 0.6 M NaCl solution at 25 °C, are 27.5 and 246.7 mm y−1 for the alloys extruded with and without artificial cooling, respectively. The remarkably improved corrosion resistance is mainly attributed to the reduced nobility of cathodic Al5Fe2 particles, which results in retarded microgalvanic corrosion in the corrosive condition. Metallurgical factors affecting the electrochemical nobility of Al5Fe2 particles are discussed.
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Improved corrosion resistance of Mg–8Sn–1Zn–1Al alloy subjected to low-temperature Indirect Extrusion
Corrosion Science, 2018Co-Authors: Soo-min Baek, Jeong Su Kang, Hyungjoon Shin, Sung Soo ParkAbstract:Abstract We report that the corrosion resistance of Mg–8Sn–1Zn–1Al alloy is significantly improved by the application of a low-temperature Indirect Extrusion process utilizing artificial cooling. It was found that the corrosion rates, measured by immersion tests in 0.6 M NaCl solution at 25 °C, are 27.5 and 246.7 mm y−1 for the alloys extruded with and without artificial cooling, respectively. The remarkably improved corrosion resistance is mainly attributed to the reduced nobility of cathodic Al5Fe2 particles, which results in retarded microgalvanic corrosion in the corrosive condition. Metallurgical factors affecting the electrochemical nobility of Al5Fe2 particles are discussed.
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High-strain-rate superplasticity of fine-grained Mg–6Zn–0.5Zr alloy subjected to low-temperature Indirect Extrusion
Scripta Materialia, 2017Co-Authors: Sung Soo ParkAbstract:Abstract A commercial Mg–6Zn–0.5Zr alloy was subjected to low-temperature Indirect Extrusion for grain refinement and the tensile properties of the extruded alloy at 250 °C were investigated. After Extrusion, the alloy showed finely recrystallized grains with an average size of 1.6 μm. High-strain-rate superplasticity was observed in the fine-grained alloy, which exhibited a tensile elongation of up to 800% at a strain rate of 0.01 s−1. Experimental results demonstrating the occurrence of grain boundary sliding during the high-strain-rate superplastic deformation are presented.
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high strain rate superplasticity of fine grained mg 6zn 0 5zr alloy subjected to low temperature Indirect Extrusion
Scripta Materialia, 2017Co-Authors: Sung Soo ParkAbstract:Abstract A commercial Mg–6Zn–0.5Zr alloy was subjected to low-temperature Indirect Extrusion for grain refinement and the tensile properties of the extruded alloy at 250 °C were investigated. After Extrusion, the alloy showed finely recrystallized grains with an average size of 1.6 μm. High-strain-rate superplasticity was observed in the fine-grained alloy, which exhibited a tensile elongation of up to 800% at a strain rate of 0.01 s−1. Experimental results demonstrating the occurrence of grain boundary sliding during the high-strain-rate superplastic deformation are presented.
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Enhanced strength and plasticity of Mg–6Zn–0.5Zr alloy by low-temperature Indirect Extrusion
Journal of Alloys and Compounds, 2017Co-Authors: Soo-min Baek, Sung Soo ParkAbstract:Abstract The microstructure and tensile properties of Mg–6Zn–0.5Zr alloy processed by low-temperature Indirect Extrusion utilizing artificial cooling were investigated. Remarkable grain refinement was obtained by the application of artificial cooling, resulting in an increase in the yield strength of as much as 53 MPa at room temperature, as compared to the case (245 MPa) of Indirect Extrusion without artificial cooling. Besides this, the fine-grained alloy was found to have superplastic properties at elevated temperature, revealing tensile elongations of 720–810% at 200 °C at strain rates of 2 × 10 −4 –1 × 10 −3 s −1 . Mechanisms responsible for the high strength and superplastic properties are discussed.
Di Zhang - One of the best experts on this subject based on the ideXlab platform.
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Effect of Extrusion dies angle on the microstructure and properties of (TiB+TiC)/Ti6Al4V in situ titanium matrix composite
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Guangfa Huang, Weijie Lu, Liqiang Wang, Di ZhangAbstract:Abstract Forged 5 vol% (TiB+TiC)/Ti6Al4V titanium matrix composite billets with a heterogeneous reinforced structure was successfully hot Indirect extruded with different dies angle (θ=45°, 60° and 75°) at 1303 K. The dies angle was found to work as one key factor to change the microstructures and mechanical properties. Detail investigation on the microstructural evolution revealed that the significant grain refinement was obtained after Extrusion due to dynamic recrystallization, the fully dynamic recrystallization takes place during Indirect Extrusion at dies angle 75°. In situ TiB and TiC reinforcements were also significantly refined by the Indirect Extrusion process, while highly developed preferred orientation of TiB short fibers along Extrusion direction. Meanwhile, the mechanical properties showed that the ultimate tensile strength, yield strength and elongation exhibited a simultaneous increase after the Indirect Extrusion, especially on the ductility of the materials. The strength was slightly improved but not too much by hot Extrusion. However, both tensile strength and elongation to fracture were reduced as the Extrusion dies angle enlarged from 45° to 75°. Higher strength and elongation were obtained with optimal dies angle 45°, confirmed by matrix refinement, dynamical recrystallization and the optimal aspect ratio of TiB short fibers. Therefore, the optimal hot Extrusion with the Extrusion dies angle should be controlled less than 60°.
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effect of Extrusion dies angle on the microstructure and properties of tib tic ti6al4v in situ titanium matrix composite
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Guangfa Huang, Weijie Lu, Liqiang Wang, Di ZhangAbstract:Abstract Forged 5 vol% (TiB+TiC)/Ti6Al4V titanium matrix composite billets with a heterogeneous reinforced structure was successfully hot Indirect extruded with different dies angle (θ=45°, 60° and 75°) at 1303 K. The dies angle was found to work as one key factor to change the microstructures and mechanical properties. Detail investigation on the microstructural evolution revealed that the significant grain refinement was obtained after Extrusion due to dynamic recrystallization, the fully dynamic recrystallization takes place during Indirect Extrusion at dies angle 75°. In situ TiB and TiC reinforcements were also significantly refined by the Indirect Extrusion process, while highly developed preferred orientation of TiB short fibers along Extrusion direction. Meanwhile, the mechanical properties showed that the ultimate tensile strength, yield strength and elongation exhibited a simultaneous increase after the Indirect Extrusion, especially on the ductility of the materials. The strength was slightly improved but not too much by hot Extrusion. However, both tensile strength and elongation to fracture were reduced as the Extrusion dies angle enlarged from 45° to 75°. Higher strength and elongation were obtained with optimal dies angle 45°, confirmed by matrix refinement, dynamical recrystallization and the optimal aspect ratio of TiB short fibers. Therefore, the optimal hot Extrusion with the Extrusion dies angle should be controlled less than 60°.
Sung Hyuk Park - One of the best experts on this subject based on the ideXlab platform.
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high speed Indirect Extrusion of mg sn al zn alloy and its influence on microstructure and mechanical properties
Journal of Alloys and Compounds, 2016Co-Authors: Sung Hyuk Park, Jonghun YoonAbstract:Abstract This investigation into the effect of Indirectly extruding Mg–7Sn–1Al–1Zn (TAZ711) alloy at high exit speeds on the microstructure and tensile properties found no evidence of surface cracking, not even at the maximum speed tested of 27 m/min. This high-speed extrudability is attributed to the relatively high incipient melting temperature of the alloy (535 °C), which results from the formation of a thermally stable Mg 2 Sn phase. All extruded samples exhibited a completely recrystallized (DRXed) structure consisting of coarse DRXed grains with few particles in combination with relatively fine DRXed grains containing numerous fine precipitates. With an increase in Extrusion speed, the total amount of Mg 2 Sn precipitates decreased and the size and quantity of coarse DRXed grains increased due to a rise in temperature during Extrusion. This has the effect of reducing the strength of the extruded alloy through a reduction in precipitation and grain-boundary strengthening, yet the elongation of the extruded alloy remains essentially the same due to a loss of ductility caused by the increase in DRXed grain size.
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die angle dependency of microstructural inhomogeneity in an Indirect extruded az31 magnesium alloy
Journal of Materials Processing Technology, 2015Co-Authors: Hui Yu, Sung Hyuk ParkAbstract:Abstract The variation induced in the microstructural inhomogeneity of AZ31 alloy subjected to Indirect Extrusion was studied using tool steel dies with angles of 30°, 60° and 90°. Finite element modeling (FEM) of this Extrusion process was also carried out to determine the metal flow, temperature evolution and effective strain distribution, which were then correlated with the observed microstructural changes. Although all extruded samples were found to have a bimodal microstructure consisting of equiaxed fine recrystallized (DRXed) grains and elongated coarse unDRXed grains, the inhomogeneity of their microstructural characteristics (i.e., DRX fraction and texture intensity) decreased in cross section with an increase in the die angle. The FEM analysis also demonstrated that a faster metal flow, higher temperature, and larger effective strain are generated in an alloy extruded with a 90° die angle, and that this enhances DRX behavior during Extrusion and ultimately results in a homogeneously DRXed microstructure.
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Improving the tensile strength of Mg–7Sn–1Al–1Zn alloy through artificial cooling during Extrusion
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Sung Hyuk ParkAbstract:Abstract An Mg–7Sn–1Al–1Zn alloy known to have excellent extrudability and superior strength was subjected to artificial cooling during Indirect Extrusion by directly spraying water onto the extruded rod at the die exit. The results obtained revealed that this artificial cooling dramatically reduces the temperature of the deformation zone during Extrusion, thereby creating a finer grain size, an intensified texture and a greater amount of precipitates when compared to Extrusion without artificial cooling. The yield and tensile strength of the extruded alloy is also significantly improved, which is attributed to the effects of grain refinement in combination with an enhanced texture and precipitate hardening.
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Microstructure and Yield Asymmetry Behavior of Indirect-extruded Mg-Sn-Al-Zn Alloys
Transactions of materials processing, 2012Co-Authors: Sung Hyuk ParkAbstract:Abstract Mg-(9-x)Sn-xAl-1Zn (x=1, 2, 3 and 4 wt.%) alloys were subjected to Indirect Extrusion, and the microstructure and mechanical properties of the as-extruded Mg-Sn-Al-Zn (TAZ) alloys were investigated. The TAZ 811 alloy exhibited a finer grain structure than the TAZ 541 alloy due to a larger number of Mg 2 Sn particles, which pinned the grain boundaries and prevented growth of recrystallized grains. The TAZ alloys showed an unusual yield asymmetry behavior. The tension-compression yield asymmetry increased with decreasing average grain size. The TAZ 811 alloy with a small grain size exhibited a larger yield asymmetry than that of the TAZ 541 alloy having a relatively large grain size, which is mainly attributed to the low Al content and large number of second phase particles in the TAZ 811 alloy. Key Words : Magnesium Alloy, Indirect Extrusion, Microstructure, Yield Asymmetry, Particles 1. 서 론 그네슘 마그네슘 합금은 사용 가능한 구조용 소재 중 가장 밀도가 낮은 경량 금속 소재이면서, 높은 비강도, 뛰어난 기계가공성, 진동흡수능, 전자파 차폐성와 같은 우수한 특성으로 인해 자동차 산업 및 전자부품 산업에 주목을 받고 있는 재료이다. 현재 사용중인 마그네슘 합금 부품은 주조재가 주류를 이루었으나, 최근 들어 기계적 물성이 우수한 가공재(압출재, 압연재, 단조재 등)에 대한 연구가 활발히 진행되고 있다. 압출재의 경우에 있어, AZ61, AZ80, ZK60 과 같은 상용 마그네슘 합금은 알루미늄 합금 대비 매우 낮은 최대압출속도를 가지고 있어 마그네슘 압출재 적용에 주 요한장애물로여겨지고있다[1]. 이러한상용마합금이낮은압출속도를보이는이유는낮은 녹는점을 가지는 Mg
Guangfa Huang - One of the best experts on this subject based on the ideXlab platform.
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Effect of Extrusion dies angle on the microstructure and properties of (TiB+TiC)/Ti6Al4V in situ titanium matrix composite
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Guangfa Huang, Weijie Lu, Liqiang Wang, Di ZhangAbstract:Abstract Forged 5 vol% (TiB+TiC)/Ti6Al4V titanium matrix composite billets with a heterogeneous reinforced structure was successfully hot Indirect extruded with different dies angle (θ=45°, 60° and 75°) at 1303 K. The dies angle was found to work as one key factor to change the microstructures and mechanical properties. Detail investigation on the microstructural evolution revealed that the significant grain refinement was obtained after Extrusion due to dynamic recrystallization, the fully dynamic recrystallization takes place during Indirect Extrusion at dies angle 75°. In situ TiB and TiC reinforcements were also significantly refined by the Indirect Extrusion process, while highly developed preferred orientation of TiB short fibers along Extrusion direction. Meanwhile, the mechanical properties showed that the ultimate tensile strength, yield strength and elongation exhibited a simultaneous increase after the Indirect Extrusion, especially on the ductility of the materials. The strength was slightly improved but not too much by hot Extrusion. However, both tensile strength and elongation to fracture were reduced as the Extrusion dies angle enlarged from 45° to 75°. Higher strength and elongation were obtained with optimal dies angle 45°, confirmed by matrix refinement, dynamical recrystallization and the optimal aspect ratio of TiB short fibers. Therefore, the optimal hot Extrusion with the Extrusion dies angle should be controlled less than 60°.
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effect of Extrusion dies angle on the microstructure and properties of tib tic ti6al4v in situ titanium matrix composite
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Guangfa Huang, Weijie Lu, Liqiang Wang, Di ZhangAbstract:Abstract Forged 5 vol% (TiB+TiC)/Ti6Al4V titanium matrix composite billets with a heterogeneous reinforced structure was successfully hot Indirect extruded with different dies angle (θ=45°, 60° and 75°) at 1303 K. The dies angle was found to work as one key factor to change the microstructures and mechanical properties. Detail investigation on the microstructural evolution revealed that the significant grain refinement was obtained after Extrusion due to dynamic recrystallization, the fully dynamic recrystallization takes place during Indirect Extrusion at dies angle 75°. In situ TiB and TiC reinforcements were also significantly refined by the Indirect Extrusion process, while highly developed preferred orientation of TiB short fibers along Extrusion direction. Meanwhile, the mechanical properties showed that the ultimate tensile strength, yield strength and elongation exhibited a simultaneous increase after the Indirect Extrusion, especially on the ductility of the materials. The strength was slightly improved but not too much by hot Extrusion. However, both tensile strength and elongation to fracture were reduced as the Extrusion dies angle enlarged from 45° to 75°. Higher strength and elongation were obtained with optimal dies angle 45°, confirmed by matrix refinement, dynamical recrystallization and the optimal aspect ratio of TiB short fibers. Therefore, the optimal hot Extrusion with the Extrusion dies angle should be controlled less than 60°.
H C Kwon - One of the best experts on this subject based on the ideXlab platform.
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Fabrication and characterization of Ti-Cu clad materials by Indirect Extrusion
Journal of Materials Processing Technology, 2007Co-Authors: I J Oh, C.-s. Kang, H C KwonAbstract:Abstract This study was to investigate the effects of Extrusion condition (Extrusion temperature, Extrusion ratio, dies angle, initial Ti thickness) on the fabrication of Ti–Cu clad material for high conductivity and high corrosion resistance, using Indirect Extrusion method in which there is no friction between container and billet. The range of Extrusion temperature, Extrusion ratio, dies angle and initial Ti thickness were changed from 700 to 900 °C, from 10 to 38, from 20° to 50°, and from 1.8 to 4.8 mm, respectively. Extrusion pressure decreased with increasing Extrusion temperature owing to the reduction of flow stress. However, increment of Extrusion temperature resulted in the drawback of lubricant effect between dies and billet. Extrusion pressure increased with increasing Extrusion ratio and initial Ti thickness. Extrusion pressure was also affected by dies angle. Namely, the maximum Extrusion pressure was increased with smaller dies angle because the friction between billet and dies increased with decreasing of dies angle. The thickness of interface layer between titanium and copper was increased with increasing Extrusion temperature. The interface layer composed of hard inter-metallic phases which may act a reducer of bonding strength depending upon its thickness.
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Fabrication and characterization of Ti-Cu clad materials by Indirect Extrusion
Journal of Materials Processing Technology, 2007Co-Authors: Jong Soon Lee, H. T. Son, C. H. Yun, S. C. Lim, I.h. Oh, C.-s. Kang, H C KwonAbstract:This study was to investigate the effects of Extrusion condition (Extrusion temperature, Extrusion ratio, dies angle, initial Ti thickness) on the fabrication of Ti-Cu clad material for high conductivity and high corrosion resistance, using Indirect Extrusion method in which there is no friction between container and billet. The range of Extrusion temperature, Extrusion ratio, dies angle and initial Ti thickness were changed from 700 to 900 ??C, from 10 to 38, from 20?? to 50??, and from 1.8 to 4.8 mm, respectively. Extrusion pressure decreased with increasing Extrusion temperature owing to the reduction of flow stress. However, increment of Extrusion temperature resulted in the drawback of lubricant effect between dies and billet. Extrusion pressure increased with increasing Extrusion ratio and initial Ti thickness. Extrusion pressure was also affected by dies angle. Namely, the maximum Extrusion pressure was increased with smaller dies angle because the friction between billet and dies increased with decreasing of dies angle. The thickness of interface layer between titanium and copper was increased with increasing Extrusion temperature. The interface layer composed of hard inter-metallic phases which may act a reducer of bonding strength depending upon its thickness. ?? 2006 Elsevier B.V. All rights reserved.