• Title, Summary, Keyword: Severe Plastic Deformation

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Analysis of Plastic Deformation Behavior during Groove pressing (Groove Pressing 공정을 통한 소성 변형 거동 연구)

  • Yoon, S.C.;Krishnaiah, A.;Chakkingal, U.;Kim, H.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.425-426
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    • 2008
  • Elasto-plastic finite element analysis was carried out for analyzing the severe plastic deformation behavior of copper specimens during groove pressing. Deformation localization was studied in terms of strain variations along the longitudinal direction. Plastic strain is lower at the local interface between the shear and the flat regions, which receive very little shear during the pressing cycle. Strain localization is more intensified with the number of rove pressing cycles, although the average strain level increases.

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Finite Element Analysis of Half Channel Angular Extrusion (HCAE) as a New Severe Plastic Deformation Process (새로운 강소성 가공 공정으로서 Half Channel Angular Extrusion(HCAE)의 유한요소해석)

  • Kim, K.J.
    • Transactions of Materials Processing
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    • v.21 no.3
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    • pp.164-171
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    • 2012
  • This paper focuses on the development of a new SPD (severe plastic deformation) process named HCAE (half channel angular extrusion). HCAE technology is based on principled similar to ECAE, but imposes a larger amount and more effective plastic deformation on materials. The amount of shear deformation can be altered by varying the process parameters. Finite element analyses of HCAE were conducted in order to investigate the characteristics of deformation during HCAE and the simulated results show that the predicted value of imposed plastic strain in a single pass reaches 2.5.

Finite Element Analysis of Continuous Rotary-Die Equal Channel Angular Pressing (연속 회전 등통로각압축 공정의 유한요소해석)

  • Yoon, Seung-Chae;Seo, Min-Hong;Kim, Hyoung-Seop
    • Transactions of Materials Processing
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    • v.15 no.7
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    • pp.524-528
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    • 2006
  • Although equal channel angular pressing (ECAP), imposing large plastic shear strain deformation by moving a workpiece through two intersecting channels, is a promising severe plastic deformation method for grain refinement of metallic materials, its batch type characteristic makes ECAP inefficient for multiple-passing. Rotary-die ECAP (RDECAP) proposed by Nishida et al. can achieve high productivity by using continuous processing without taking out the samples from the channel. However, plastic deformation behavior during RD-ECAP has not been investigated. In this study, material plastic flow and strain hardening behavior of the workpiece during RD-ECAP was investigated using the finite element method. It was found that plastic deformation becomes inhomogeneous with the number of passes due to an end effect, which was not found seriously in ECAP. Especially, decreasing corner gap with increasing the number of passes was observed and explained by the strain hardening effect.

Changes of Low Cycle Fatigue Behavior of AI-Mg-Si Alloy with Severe Plastic Deformation and Heat Treatment (강소성 가공 및 열처리에 의한 Al-Mg-Si합금의 저주기 피로특성변화)

  • Kim, W.H.;Kwun, S.I.
    • Journal of the Korean Society for Heat Treatment
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    • v.22 no.4
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    • pp.217-222
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    • 2009
  • The effects of severe plastic deformation by equal channel angular pressing (ECAP) and subsequent heat treatment on the low cycle fatigue behaviors of Al-Mg-Si alloy were investigated. The specimens which were peak aged at $175^{\circ}C$ after solution treatment showed cyclic hardening at all strain amplitudes, while the specimens ECAPed after solution treatment showed cyclic softening at all strain amplitudes during fatigue. The specimens aged at $100^{\circ}C$ after ECAP showed slight cyclic hardening. Various changes of cyclic fatigue behavior after severe plastic deformation and/or heat treatment were discussed in terms of the microstructural changes and precipitation conditions.

Characteristics of Plastic Deformation of Commercially Pure Aluminum in Half Channel Angular Extrusion (HCAE) (공업용 순 알루미늄의 반통로각압출(Half Channel Angular Extrusion) 공정에서의 소성 변형 특성)

  • Kim, Kyung Jin;Cho, Hyun Deog
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.1
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    • pp.120-127
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    • 2013
  • A novel severe plastic deformation process named half channel angular extrusion (HCAE) is proposed in order to produce bulk UFG materials. In HCAE process, equal channel angular extrusion (ECAE) and conventional forward extrusion process is integrated to increase the strain per pass and effectiveness of the SPD process. Three-dimensional finite element analysis was carried out to study the deformation behavior of the materials in the HCAE process. HCAE process was performed experimentally on commercially pure aluminum (AA1050) and micro-Vickers hardness test was used to measure the distribution of hardness on the section of normal to the extrusion direction. The results show that HCAE is able to impose more intensive strains per pass and give rise to higher micro-hardness than ECAE.

Analysis of Deformation Behavior due to Die Angles during Equal Channel Angular Pressing (ECAP) with Pure-Zirconium (Pure-Zirconium의 ECAP 공정에서의 금형의 교차각과 만곡각에 따른 재료의 변형거동해석)

  • Kwon, G.H.;Chae, S.W.;Kwun, S.I.;Kim, M.H.;Hwang, S.K.
    • Proceedings of the KSME Conference
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    • pp.747-753
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    • 2000
  • There has been a number of investigations in recent years reporting the results obtained on the structure and properties of metals deformed to severe plastic deformation (SPD). Being deformed to SPD, ultra-fine grains (UFG) are usually formed, and UFG structure exhibits fundamental differences in original physical properties. One method often used to obtain SPD is equal channel angular pressing (ECAP). In order for this technique to be exploited, it is important to understand the deformation behavior during the ECAP processing and relationship to the configuration of die. The finite element method (FEM) has been used to investigate this issue. It has been found that the plastic deformation is sensitive to the channel angle and material properties and is not uniform across the width of the specimen and the pressing load is relative to deformation during the ECAP processing.

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Finite Element Analysis on the Effect of Die Corner Angle in Equal Channel Angular Pressing Process of Powders (분말 ECAP 공정에 미치는 금형 모서리각 효과에 대한 유한요소해석)

  • Yoon, Seung-Chae;Bok, Cheon-Hee;Quang, Pham;Kim, Hyoung-Seop
    • Journal of Korean Powder Metallurgy Institute
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    • v.14 no.1
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    • pp.26-31
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    • 2007
  • Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve both real density and grain refinement of metallic powders. ECAP (Equal Channel Angular Pressing), one of the most promising processes in SPD, was used for the powder consolidation method. For understanding the ECAP process, investigating the powder density as well as internal stress, strain distribution is crucial. We investigated the consolidation and plastic deformation of the metallic powders during ECAP using the finite element simulations. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method. Effects of processing parameters on densification and density distributions were investigated.

Preform Effect on the Plastic Deformation Behavior of Workpieces in Equal Channel Angular Pressing (Equal Channel Angular Pressing 가공 중 소성 변형에 미치는 재료의 초기 형상 효과)

  • Yoon, Seung-Chae;Seo, Min-Hong;Kim, Hyoung-Seop
    • Transactions of Materials Processing
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    • v.15 no.5
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    • pp.382-386
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    • 2006
  • Preform design is an effective means of achieving the homogeneous deformation of workpiece materials and decreased load in metal forming. However, this approach has not been applied to equal channel angula. pressing (ECAP). In this paper, plastic deformation behavior of workpieces having four different preform shapes during ECAP was investigated using finite element analyses. The results indicated that a preform design of the workpiece head has a beneficial effect on homogeneous deformation, reducing the maximum pressing load at the initial stage and eliminating folding defects at strain concentration points.

Effects of Processing Routes on the Deformation Behavior of an AZ61 Mg Alloy by Half Channel Angular Extrusion(HCAE) using 3D Finite Element Analysis (유한요소해석을 이용한 HCAE 공정의 가공 경로가 AZ61 마그네슘 합금의 변형 특성에 미치는 영향에 대한 연구)

  • Lee, S.I.;Yoon, J.H.;Kim, K.J.
    • Transactions of Materials Processing
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    • v.23 no.3
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    • pp.151-158
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    • 2014
  • Half channel angular extrusion(HCAE) is the integration of equal channel angular extrusion(ECAE), which is a well-known severe plastic deformation(SPD) method, with conventional forward extrusion in order to increase the strain per pass and effectiveness of the grain refinement. In the current study, the effects of processing routes during HCAE(Routes A, B, and C) on the strain distribution of the specimens have been investigated for an AZ61 Mg alloy by using three-dimensional finite element analysis. Comparisons with the results from a multi-pass of ECAE are made.