• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.206-209
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• 2000

Groove pressing which is analogous to groove rolling in the aspect of deformation mode was designed and influence of the uncommon shear deformation on the development of texture and R value was investigated. Texture developed by the groove pressing were measured as well as predicted. It was found out that the main component in the developed texture was {40。, 45。, 0。} in ODF which was regarded as a rotated Bs component and rarely observed in a plain rolling. The maximum R value was predicted to be 3.8 in 45。 direction which might be attributed to the new component.

• The Journal of Natural Sciences
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• v.7
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• pp.83-90
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• 1995

The microstructural and textural development during rolling is compared in two Hadifield's steels (high Mn steel), one having low carbon content (0.65 wt.%) and the other high carbon (1.35 wt.%).In low carbon Hadfield's steel (LCHS) mixed microstructures are formed which contain intrinsic stacking faults, deformation twins, and brass type shear bands. The deformation twins are thought to be formed by the stacking of intrinsic stacking faults. The similar development to 70-30 brass texture is observed in early deformation. However the abnormal texture is developed after 40 % deformation, which is thought to be due to the martensite phase transformation. In high carbon Hadfield's steel (HCHS) mixed substructures of dislocation tangles, deformation twins, and shear bands (both copper and brass type) are found to develop. The texture development is similar to that of 70-30 brass. This is consistant with no carbon segregation and no martensitic phase transformation in HCHS. In spite of the difference of substructure and texture development during rolling in two steels, the difference in stacking fault energy is measured to be small ($2 mJm^-2$). The carbon segregation is only occurred in LCHS. Thus it is thought that the carbon segregation influence the microstructure and texture development during rolling. This is related with martensite phase transformation in LCHS.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.11-18
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• 2004

Asymmetric rolling, in which the circumferential velocities of the upper and lower rolls are different, can give rise to intense plastic shear strains and in turn shear deformation textures through the sheet thickness. The ideal shear deformation texture of fcc metals can be approximated by the <111> // ND and $\{001\}<110>$ orientations, among which the former improves the deep drawability. The ideal shear deformation texture for bcc metals can be approximated by the Goss $\{110\}<001>\;and\;\{112\}<111>$ orientations, among which the former improves the magnetic permeability along the <100> directions and is the prime orientation in grain oriented silicon steels. The intense shear strains can result in the grain refinement and hence improve mechanical properties. Steel sheets, especially ferritic stainless steel sheets, and aluminum alloy sheets may exhibit an undesirable surface roughening known as ridging or roping, when elongated along RD and TD, respectively. The ridging or roping is caused by differently oriented colonies, which are resulted from the <100> oriented columnar structure in ingots or billets, especially for ferritic stainless steels, that is not easily destroyed by the conventional rolling. The breakdown of columnar structure and the grain refinement can be achieved by asymmetric rolling, resulting in a decrease in the ridging problem.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.215-217
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• 2004

In order to obtain the initial starting sample having a random texture and fine grains, aluminum alloy 3103 sheets were repeatedly deformed by CCSS up to six passages and subsequently annealed at $300^{\circ}C$ for 1h. These samples were cold rolled at room temperature and also warm rolled at $250^{\circ}C$. Changes in rolling temperature gave rise to the different texture evolution. Warm rolling led to the pronounced texture gradients comprising the shear texture at the surface and the rolling texture at the sheet center. The formation of the rolling texture components, i.e., the ${\beta}$-fiber, was promoted by cold rolling than warm rolling.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.219-221
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• 2006

Asymmetrical rolling was performed by rolling AA 1050 sheets with different velocities of upper and lower rolls. In order to study the effect of roll gap geometry on the evolution of strain states and textures during asymmetrical rolling, the reduction per rolling pass was varied. After asymmetrical rolling, the outer thickness layers depicted shear textures and the center thickness layers displayed a random texture. With decreasing reduction per an asymmetrical rolling pass, the thickness layers depicting shear textures increases. The strain states associated with asymmetrical rolling were investigated by simulations with the finite element method (FEM).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.349-355
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• 1999

The texture inhomogeniety during rolling is one of the greatest problems. Especially, shear texture develops more easily during ferritic rolling of steel sheets at high temperatures due to friction between rolls and the material. In this study, the influence of front and back tensions on the texture development during ferritic rolling has been studied. The rolling textures were simulated using the full constrains Taylor-Bishiop-Hill model with the strain history obtained from finite element analysis. The calculated textures showed that the back tension rolling could reduce the shear component more effectively than front tension or rolling without tension. However, the experimental results showed that the lension effect was very small compared to our prediction. It might be attributed to initial texture and difference in frictions between simulation and experiments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.84-86
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• 2007

Aluminum sheets were asymmetrically cold rolled without lubrication by using different roll velocities of upper and lower rolls in order to intensify the shear deformation. During asymmetrical cold rolling of aluminum sheets, a reduction per a rolling pass, initial sheet thickness, roll diameter, roll velocity ratio were varied to investigate the effect of rolling parameters. The formation of through thickness shear texture was related to the ratio of the contact length between the roll and sample($l_c$) to the sheet thickness(d). The strain states associated with asymmetrical rolling were investigated by the finite element method (FEM) simulation. FEM results indicated that the evolution of deformation texture in a thickness layer is strongly governed by integrated values of strain rates $\dot{\varepsilon}_{13}$ and $\dot{\varepsilon}_{11}$ along the streamline in the roll gap.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.382-387
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• 2004

The continuous confined strip shearing (CCSS) based on the equal channel angular pressing (ECAP) was modeled by means of a rigid-plastic two-dimensional finite element method (FEM). Parallel to the simulations, samples of AA 1050 sheets were experimentally deformed by CCSS. The CCSS deformation led to the formation of through thickness texture gradients comprising a strong shear texture in the sheet center and weak shear textures in the sheet surfaces. FEM analysis revealed variations in the strain component $\varepsilon_13$ along the sample thickness direction, which gave rise to the evolution of different textures. A high friction between the sample and die surface was responsible for lowering intensities of the shear texture components in thickness layers close to the surfaces.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.483-486
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• 2005

In order to study the effect of strain states on the formation of shear textures during rolling in fcc metals, the evolution of textures was simulated by the full constrain model using various ideal strain states. Considering rolling as a two-dimensional problem, i.e., $\varepsilon_{22}\;=\;\varepsilon_{12}\;=\;\varepsilon_{23}\;=\;0$, the deviation from the plane-strain state manifest itself as nonzero contribution of $\varepsilon_{13}$. With increasing variations of $\varepsilon_{13}$, shear textures develop. The sign of ell hardly affects the evolution of textures. The texture simulation with various idealized strain states indicates that the ratio $\mid\varepsilon_{13}\mid/\mid\varepsilon_{11}\mid$ in each time interval in a roll gap plays a dominant role in the evolution of textures during rolling.

• Transactions of Materials Processing
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• v.29 no.1
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• pp.27-36
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• 2020

The Goss texture component of {110}<001> is well known as one of the best texture components to improve the magnetic properties of electrical steel sheets. The small amount of the Goss texture component is obtained at the surface of the steel sheet by shear deformation due to friction between the steel sheet and the roll during conventional symmetric rolling. This study aims to identify a method to obtain high intensity of the Goss texture component not only at the surface but in the whole layer of the steel sheet by shear deformation of asymmetric rolling. Low carbon steel sheets, which have different initial texture, were asymmetrically rolled by about 50%, 70%, and 80%. The pole figures of the top, center, and bottom layers of the initial and asymmetrically rolled low carbon steel sheets were measured by an X-ray diffractometer. Based on the measured pole figures of these samples, the intensities of the main texture components were analyzed for the initial and asymmetrically rolled low carbon steel sheets. As a result, the initial low carbon steel sheet with the γ-fiber component showed a higher intensity of the Goss texture component in the whole layer than the steel sheet with other texture components after asymmetric rolling.