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Polycrystalline model for FE-simulation of micro forming processes 被引量:3
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作者 王春举 郭斌 单德彬 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第6期1362-1366,共5页
A new polycrystal model was presented from the viewpoint of polycrystal structure of the billets considering free surface effects.In the model,the billet was divided into three portions,such as free surface portion,tr... A new polycrystal model was presented from the viewpoint of polycrystal structure of the billets considering free surface effects.In the model,the billet was divided into three portions,such as free surface portion,transition portion and internal portion.The grains in free surface portion were considered the single grains,and the anisotropy of the grains was taken into account by introducing grain orientation to explain the inhomogeneous deformation.In the transition portion,the effects of the neighbouring grains were adopted in the model.The grains in the internal portion were considered the polycrystalline material.With the developed model,the upsetting deformation process was simulated by the MSC Superform software.The scatter of the flow stress and inhomogeneous deformation was observed by analysis of the model.The comparisons show that the computational results are good agreed with the experimental results.This means that the presented model is effective. 展开更多
关键词 micro forming size effect polycrystal model inhomogeneous deformation
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Constitutive model for thin sheet metal with one or several grains across thickness in micro-forming
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作者 王倩 董湘怀 +2 位作者 章海明 李河宗 申昱 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第5期1428-1434,共7页
Effects of four factors on thin sheet metal flow stress were considered, including grain size d, thickness t, grain number across thickness (t/d ratio) and surface property. Surface model was adopted to quantitative... Effects of four factors on thin sheet metal flow stress were considered, including grain size d, thickness t, grain number across thickness (t/d ratio) and surface property. Surface model was adopted to quantitatively describe the effect of t/d ratio on flow stress for pure copper. It is predicted that when t/d ratio is larger than a critical value, effect of t/d ratio on flow stress can be neglected. Existence of critical t/d ratio changes the Hall-Petch relationship and evolution of flow stress with thickness. A criterion was proposed to determine critical t/d ratio. Then a comprehensive constitutive model was developed to consider all the four factors, with parameters determined by fitting experimental data of high purity Ni. The predicted results show the same tendencies with experiment results. Particularly when t/d ratio decreases, Hall-Petch relationship and evolution of true stress show varied slopes with two transition points. 展开更多
关键词 constitutive model flow stress micro forming size effect
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Micro Extrusion of Ultrafine Grained Titanium Prepared by ECAP 被引量:2
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作者 王效岗 LIU Jianlong +3 位作者 ZHAO Xicheng LIU Xiaoyan XIE Haibo JIANG Zhengyi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第2期437-443,共7页
Micro compression and micro extrusion experiments of ultrafine grained titanium cylindrical specimens in diameters of 4, 2, and 1 mm prepared by equal channel angular pressing(ECAP) were conducted on the micro plast... Micro compression and micro extrusion experiments of ultrafine grained titanium cylindrical specimens in diameters of 4, 2, and 1 mm prepared by equal channel angular pressing(ECAP) were conducted on the micro plastic forming test machine. The effects of specimen size, grain size, deformation temperature and extrusion speed on the flow stress and forming properties of the ultrafine grained pure titanium were investigated. The flow stress of ultrafine grained pure titanium specimen decreases with decreasing specimen size. The yield limit of pure titanium with refined grain prepared by ECAP is significantly greater than that of coarse grained specimen. Also the research results show that the flow stress of specimen increases with decreasing deformation temperature and with the increase of the strain rate, and the ultrafine grained pure titanium possesses good micro forming properties at deformation temperature of 300 ℃. 展开更多
关键词 micro forming ECAP pure titanium flow stress micro extrusion
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The Research on Micro Electronic-Magnetic Forming of Sheet Metal
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作者 ZHAO Qing-juan GUO Bin +3 位作者 WANG Chun-ju SHAN De-bin YU Hai-ping LI Chun-feng 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2012年第S1期434-437,共4页
Micro channel of T2 copper were molding through electronic-magnetic forming experiments.Laser scanning confocal microscope and contourgraph were used to measure the section profile and sheet thickness.The effects of v... Micro channel of T2 copper were molding through electronic-magnetic forming experiments.Laser scanning confocal microscope and contourgraph were used to measure the section profile and sheet thickness.The effects of voltage,shape of channel and discharge cycles on laws of metal flow were studied.Results showed that forming depth of micro channel and thinning of sheet thickness increased as the increasing of the voltage.Mold-filling capacity of components formed by two molds with different structures had been increased when the voltage was increased.Mold with semicircle structure facilitate the material flow and the forming depth of parts was relative large.Semicircle structure was better than taper structure in mold-filling capacity.A number of small pulse discharges can improve the forming quality and deformation,but local thinning in sheet metal leads to non-uniform distribution of thickness. 展开更多
关键词 electromagnetic forming array microstructure foil board micro forming micro channel
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Micro thermoplastic forming of a Pd-based metallic glass:theory and applications 被引量:1
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作者 Can Yang Le-ming Lu +3 位作者 Zhi-wu Zhao Jia-hao Li Feng Gong Jiang Ma 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2017年第4期378-384,共7页
Metallic glasses(MGs)are considered as the ideal materials for miniature fabrication because of their excellent micro thermoplastic forming ability in the supercooled liquid region.The understanding and controlling ... Metallic glasses(MGs)are considered as the ideal materials for miniature fabrication because of their excellent micro thermoplastic forming ability in the supercooled liquid region.The understanding and controlling of micro filling process are fundamental for miniature fabrication and their applications,yet presently remain unresolved issues.A universal kinetic equation was proposed to describe the filling kinetics of viscous metallic glass supercooled liquid in micro molds with general cross sectional shapes by using a Pdbased MG as the modeling material and a series of potential applications based on the micro thermoplastic forming of the MG were developed. 展开更多
关键词 Metallic glass Supercooled liquid region micro thermoplastic forming Miniature fabrication
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