The Experts below are selected from a list of 63711 Experts worldwide ranked by ideXlab platform
Daegyo Seo - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of the warm deep drawability of a transformation-induced plasticity steel sheet
Metals and Materials International, 2002Co-Authors: Daegyo Seo, Sung Ho Chang, Kyung Hwan KongAbstract:Warm deep drawability in a square cup drawing was investigated using a newly developed high-strength steel sheet with retained austenite that was transformed into martensite during formation. For this investigation, six different temperatures between room temperature and 250°C, and five different drawing ratios ranging from 2.2 to 2.6 were considered. The results showed that the maximum drawing force and the drawing depth were affected by the change in temperature, and a more stable Thickness Strain distribution was observed at elevated temperatures. However, blue shortness occurred at over 200°C. FEM analysis using the LS-DYNA code was used to compare the experimental results with the numerical results for the Thickness Strain distribution.
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A study on the warm deep drawability of sheets in Cr-coated die
KSME International Journal, 2001Co-Authors: Jae Dong Lee, Youngmoo Heo, Heon Young Kim, Sung Ho Chang, Yi Chun Choi, Daegyo SeoAbstract:Some deep drawing characteristics at elevated temperatures were investigated for the SCP1 steel sheets by using a Cr-coated die. For this investigation, six different temperatures between room temperature and 250°C, and six different drawing ratios ranging from 2.4 to 2.9 were considered. As a result, the limiting drawing ratio, the maximum drawing force and the maximum drawing depth were found to be affected sensitively by temperature, and more stable through-Thickness Strain distribution was observed at elevated temperatures. Some experimental results compared favorably with theoretical, results obtaine by using the finite element method.
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The effect of the drawbead dimensions on the weld-line movements in the deep drawing of tailor-welded blanks
Journal of Materials Processing Technology, 2001Co-Authors: Youngmoo Heo, Heon Young Kim, Sung Ho Wang, Daegyo SeoAbstract:Abstract Tailor-welded blanks made by the laser welding process with different Thickness combinations were applied in the deep drawing process without drawbeads to investigate their forming behavior. The purpose of this study is to investigate quantitatively the effects of the drawbead dimensions on the weld-line movements in the deep drawing of the tailor-welded blanks. Square blanks have been used and five different circular drawbeads of 0.0, 1.5, 2.0, 3.0, 4.0, 5.0 mm radius and also no drawbead were installed in the blank holder in the experimental apparatus. The differences in the weld-line movements and the tendencies of the Thickness Strain distributions were investigated by experimental and numerical methods. The results of the weld-line movement show that the smaller the radius of the drawbead installed, the larger are the values of the movements. Also it is shown that for Thickness Strain along the central and diagonal direction that the larger is the dimension of the drawbead, the larger are the values of maximum Thickness Strain. The drawbead adds additional reStraining forces to the blank, hence the movement of the weld line could be controlled by adequate drawbead installation.
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Characteristics of weld line movements for the deep drawing with drawbeads of tailor-welded blanks
Journal of Materials Processing Technology, 2001Co-Authors: Youngmoo Heo, Youho Choi, Heon Young Kim, Daegyo SeoAbstract:Abstract The purpose of this study is to investigate the weld line movements of laser welded tailored sheets during the deep drawing process with and without round drawbeads. Square blanks have been used and they have three different weld line locations. The differences of the weld line movements and the tendencies of the Thickness Strain distributions were investigated by experimental and analytical methods. With consideration for the amount of movement and for the Thickness Strain in the central and diagonal direction, the larger are the values, the longer are the distances from the center line to the initial weld lines. The drawbead adds additional reStraining forces to the blank, so that the movement of the weld line is reduced and the Thickness Strain distribution is changed.
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investigations of weld line movements for the deep drawing process of tailor welded blanks
Journal of Materials Processing Technology, 2000Co-Authors: Youho Choi, Youngmoo Heo, Heon Young Kim, Daegyo SeoAbstract:Abstract The purpose of this study is to investigate the weld-line movement of the laser welded sheets during deep drawing process. Two kinds of blank shape, namely square and circular, have the three different initial weld-line locations, respectively. During the deep drawing process of these specimens, the differences of weld-line movement and Thickness Strain distribution are investigated by experiment and analysis
S. Lee Semiatin - One of the best experts on this subject based on the ideXlab platform.
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The Influence of Grain Size on Twinning and Microstructure Refinement During Cold Rolling of Commercial-Purity Titanium
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2016Co-Authors: Sergey Zherebtsov, G. S. D’yakonov, Gennady A. Salishchev, Ayman A. Salem, S. Lee SemiatinAbstract:Microstructure evolution in commercial-purity titanium (CP Ti) with various initial grain sizes (1, 7, 15, and 30 μm) during plane-Strain multipass rolling to a true Thickness Strain of 2.66 at 293 K (20 °C) was established. The degree of deformation twinning was found to be strongly dependent on grain size. Twinning was rare in the material with a grain size of 1 μm. For all grain sizes >15 μm, the occurrence of twinning reached a similar, maximum level. Concurrently, the propensity for twinning enhanced the kinetics of microstructure refinement particularly for the initially coarse-grain materials. Due to the extensive twinning-induced microstructure refinement, rolling of coarse-grain (15 μm) CP Ti to a true Thickness Strain of 2.66 resulted in the formation of an ultrafine microstructure with a grain/subgrain size of 200-300 nm, a value similar to that attained for the initially micrometer-scale microstructure. The effect of grain size on twinning in titanium was discussed in the context of a disclination model.
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Formation of nanostructures in commercial-purity titanium via cryorolling
Acta Materialia, 2013Co-Authors: Sergey Zherebtsov, Gennady A. Salishchev, Ayman A. Salem, G.s. Dyakonov, V.i. Sokolenko, S. Lee SemiatinAbstract:Abstract Microstructure evolution in commercial-purity titanium during plane-Strain multipass rolling to a true Thickness Strain of 2.66 at 77 and 293 K was quantified. Deformation at both temperatures was accompanied by twinning. At 77 K, twinning was more extensive in terms of the fraction of twinned grains and the duration of the twinning stage. Rolling to a true Thickness Strain of 2.66 resulted in the formation of a microstructure with a grain/subgrain size of ∼80 nm at 77 K or ∼200 nm at 293 K. The contribution of various mechanisms to the strength of titanium following rolling at 77 and 293 K was analyzed quantitatively.
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evolution of grain and subgrain structure during cold rolling of commercial purity titanium
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Sergey Zherebtsov, Gennady A. Salishchev, Ayman A. Salem, G.s. Dyakonov, S P Malysheva, S. Lee SemiatinAbstract:The evolution of microstructure in commercial-purity titanium during cold rolling to a Thickness Strain of 2.6 was quantified using electron backscatter diffraction. The measurements were analyzed in terms of the mean grain size and the density of boundaries (the ratio of total boundary length to the scanned area). The density of high-angle boundaries as a function of Thickness Strain had three distinct stages, each of which was associated with a different mechanism of microstructure formation, i.e., (i) twinning, (ii) an increase in dislocation density and the formation of substructure, and (iii) the formation of deformation-induced high-angle boundaries. The influence of twinning on the kinetics of microstructure evolution was also interpreted.
M.p. Moutrille - One of the best experts on this subject based on the ideXlab platform.
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through Thickness Strain field measurement in a composite aluminium adhesive joint
Composites Part A-applied Science and Manufacturing, 2009Co-Authors: M.p. Moutrille, Katell Derrien, Didier Baptiste, Xavier Balandraud, Michel GrédiacAbstract:This paper presents an experimental procedure, which enables us to assess the shear Strain field in an adhesive joint between composite and aluminium. In practice, this Strain field is representative of the progressive stress transfer between a loaded structure and a composite patch used for reinforcement purposes. Digital image correlation (DIC) is used to measure the displacement field through the Thickness of a patched specimen subjected to a tensile test. The shear Strain field derives from the measured displacement field. The shear Strain clearly decreases when the distance from the free edge of the adhesive increases, as predicted by numerical and analytical models of the joint. These measurements are used to estimate the in situ shear modulus of the adhesive. It is observed that the shear modulus decreases when the shear stress increases, thereby illustrating the non-linear response of the adhesive.
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Through-Thickness Strain field measurement in a composite/aluminium adhesive joint
Composites Part A: Applied Science and Manufacturing, 2009Co-Authors: M.p. Moutrille, Katell Derrien, Didier Baptiste, Xavier Balandraud, Michel GrédiacAbstract:This paper presents an experimental procedure, which enables us to assess the shear Strain field in an adhesive joint between composite and aluminium. In practice, this Strain field is representative of the progressive stress transfer between a loaded structure and a composite patch used for reinforcement purposes. Digital image correlation (DIC) is used to measure the displacement field through the Thickness of a patched specimen subjected to a tensile test. The shear Strain field derives from the measured displacement field. The shear Strain clearly decreases when the distance from the free edge of the adhesive increases, as predicted by numerical and analytical models of the joint. These measurements are used to estimate the in situ shear modulus of the adhesive. It is observed that the shear modulus decreases when the shear stress increases, thereby illustrating the non-linear response of the adhesive.
Michel Grédiac - One of the best experts on this subject based on the ideXlab platform.
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through Thickness Strain field measurement in a composite aluminium adhesive joint
Composites Part A-applied Science and Manufacturing, 2009Co-Authors: M.p. Moutrille, Katell Derrien, Didier Baptiste, Xavier Balandraud, Michel GrédiacAbstract:This paper presents an experimental procedure, which enables us to assess the shear Strain field in an adhesive joint between composite and aluminium. In practice, this Strain field is representative of the progressive stress transfer between a loaded structure and a composite patch used for reinforcement purposes. Digital image correlation (DIC) is used to measure the displacement field through the Thickness of a patched specimen subjected to a tensile test. The shear Strain field derives from the measured displacement field. The shear Strain clearly decreases when the distance from the free edge of the adhesive increases, as predicted by numerical and analytical models of the joint. These measurements are used to estimate the in situ shear modulus of the adhesive. It is observed that the shear modulus decreases when the shear stress increases, thereby illustrating the non-linear response of the adhesive.
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Through-Thickness Strain field measurement in a composite/aluminium adhesive joint
Composites Part A: Applied Science and Manufacturing, 2009Co-Authors: M.p. Moutrille, Katell Derrien, Didier Baptiste, Xavier Balandraud, Michel GrédiacAbstract:This paper presents an experimental procedure, which enables us to assess the shear Strain field in an adhesive joint between composite and aluminium. In practice, this Strain field is representative of the progressive stress transfer between a loaded structure and a composite patch used for reinforcement purposes. Digital image correlation (DIC) is used to measure the displacement field through the Thickness of a patched specimen subjected to a tensile test. The shear Strain field derives from the measured displacement field. The shear Strain clearly decreases when the distance from the free edge of the adhesive increases, as predicted by numerical and analytical models of the joint. These measurements are used to estimate the in situ shear modulus of the adhesive. It is observed that the shear modulus decreases when the shear stress increases, thereby illustrating the non-linear response of the adhesive.
Youngmoo Heo - One of the best experts on this subject based on the ideXlab platform.
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A study on the warm deep drawability of sheets in Cr-coated die
KSME International Journal, 2001Co-Authors: Jae Dong Lee, Youngmoo Heo, Heon Young Kim, Sung Ho Chang, Yi Chun Choi, Daegyo SeoAbstract:Some deep drawing characteristics at elevated temperatures were investigated for the SCP1 steel sheets by using a Cr-coated die. For this investigation, six different temperatures between room temperature and 250°C, and six different drawing ratios ranging from 2.4 to 2.9 were considered. As a result, the limiting drawing ratio, the maximum drawing force and the maximum drawing depth were found to be affected sensitively by temperature, and more stable through-Thickness Strain distribution was observed at elevated temperatures. Some experimental results compared favorably with theoretical, results obtaine by using the finite element method.
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The effect of the drawbead dimensions on the weld-line movements in the deep drawing of tailor-welded blanks
Journal of Materials Processing Technology, 2001Co-Authors: Youngmoo Heo, Heon Young Kim, Sung Ho Wang, Daegyo SeoAbstract:Abstract Tailor-welded blanks made by the laser welding process with different Thickness combinations were applied in the deep drawing process without drawbeads to investigate their forming behavior. The purpose of this study is to investigate quantitatively the effects of the drawbead dimensions on the weld-line movements in the deep drawing of the tailor-welded blanks. Square blanks have been used and five different circular drawbeads of 0.0, 1.5, 2.0, 3.0, 4.0, 5.0 mm radius and also no drawbead were installed in the blank holder in the experimental apparatus. The differences in the weld-line movements and the tendencies of the Thickness Strain distributions were investigated by experimental and numerical methods. The results of the weld-line movement show that the smaller the radius of the drawbead installed, the larger are the values of the movements. Also it is shown that for Thickness Strain along the central and diagonal direction that the larger is the dimension of the drawbead, the larger are the values of maximum Thickness Strain. The drawbead adds additional reStraining forces to the blank, hence the movement of the weld line could be controlled by adequate drawbead installation.
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Characteristics of weld line movements for the deep drawing with drawbeads of tailor-welded blanks
Journal of Materials Processing Technology, 2001Co-Authors: Youngmoo Heo, Youho Choi, Heon Young Kim, Daegyo SeoAbstract:Abstract The purpose of this study is to investigate the weld line movements of laser welded tailored sheets during the deep drawing process with and without round drawbeads. Square blanks have been used and they have three different weld line locations. The differences of the weld line movements and the tendencies of the Thickness Strain distributions were investigated by experimental and analytical methods. With consideration for the amount of movement and for the Thickness Strain in the central and diagonal direction, the larger are the values, the longer are the distances from the center line to the initial weld lines. The drawbead adds additional reStraining forces to the blank, so that the movement of the weld line is reduced and the Thickness Strain distribution is changed.
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investigations of weld line movements for the deep drawing process of tailor welded blanks
Journal of Materials Processing Technology, 2000Co-Authors: Youho Choi, Youngmoo Heo, Heon Young Kim, Daegyo SeoAbstract:Abstract The purpose of this study is to investigate the weld-line movement of the laser welded sheets during deep drawing process. Two kinds of blank shape, namely square and circular, have the three different initial weld-line locations, respectively. During the deep drawing process of these specimens, the differences of weld-line movement and Thickness Strain distribution are investigated by experiment and analysis
