• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.285-287
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• 2006

Ultra-fine grained and high hardened Al sheet was obtained by Equal channel angular pressing (ECAP). During this process the microstructure, the hardness and the texture of AA 1050 Al alloy sheet are changed by a severe shear deformation. The plastic strain ratio after the ECAP and subsequent heat-treatment condition has been investigated in this study. It was found that the average r-value of the ECAPed and subsequent heat-treated specimen was 1.7 times higher than those of the initial Al sheet. This could be attributed to the various texture formations through the ECAP and subsequent heat-treatment of AA 1050 Aluminum alloy sheet.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.88-91
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• 2001

New type of vehicles made from thin aluminum alloy are under rapid development and some product are already on the market, but when welding sheet metal joint of aluminum alloy, the main problem are burn-through by the high heat input. The purpose of this study, it is to prevent the burn-through and to shallow penetration that AC pulse welding has diminish the penetration and to lower the droplet temperature at Al sheet metal welding. In this study, we observed the bead appearance and whether it was appeared burn through or not , as the variation of the root gap in the lap and butt-joint welding process.

• Transactions of Materials Processing
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• v.4 no.3
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• pp.222-232
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• 1995

The planar anisotripic FEM analysis for predicting earing profiles and draw-in amounts in the deep-drawing process is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vector and normal contact pressure. The consistent full set of governing relations, which is comprising euilbrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameters. The linear triangular membrane elements are used for depicting the formed sheet. In the numerical simulations of deep drawing processes of a flat-top cylindrical cup for 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.

• Journal of Welding and Joining
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• v.27 no.3
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• pp.44-51
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• 2009

In this study, welding distortion analysis is performed for various design of tube shape structures which are assembled with aluminum sheet metal. Aluminum 5052 plates of 1mm thickness are used to analyze. An efficient keyhole model, as a welding heat source, is used for the prediction of full penetration weld size and shape which is required for the thermal analysis. The thermal and mechanical material properties are considered as temperature dependent functions, due to the high temperature variations during the welding. The numerical model is calculated by using a commercial software and evaluated with the experiments. The calculation results could make a comparative study in the view of distortion for the various size and shape of structure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.222-225
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• 2006

The effect of lubrication on the development of textures and Microstructure was studied by different lubricating condition during hot rolling of AA1050 aluminum alloy. Hot rolling without lubrication led to the evolution of the pronounced through-thickness texture gradients, whereas hot rolling with lubrication gave rise to the formation of uniform rolling texture in the whole thickness layer. The variation of texture and microstructure according to hot rolling condition are investigated by X-ray diffractometer (XRD) and Electron Back-Scattered Diffraction (EBSD). The experimental results were discussed base on the finite element method (FEM) simulation. FEM calculation reveals that a larger friction between roll and sheet causes the deviated strain state from a plane strain leading to the formation of shear textures in the thickness layers close to the surface.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.265-269
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• 2009

The through-thickness variations of strain and microstructure during high-speed hot rolled 5052 aluminum alloy sheet were investigated. The specimens were rolled at temperature ranges from 410 to $560^{\circ}C$ at a rolling speed of 15 m/s without lubrication and quenched into water at an interval of 30 ms after rolling. The redundant shear strain induced by high friction between rolls and the aluminum sheet was increased largely beneath the surface at a rolling reduction above 50%. Dynamic recrystallization occurred in the surface regions of the specimen rolled under conditions of high temperatures or high rolling reductions.

• Transactions of Materials Processing
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• v.30 no.5
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• pp.242-246
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• 2021

Aluminum alloy sheet is being applied to automobiles continuously for the purpose of reducing car body weight. However, due to low formability, there's a limit to application of products with a deep forming depth such as door inner parts. Therefore, the difficult-to-form parts are mainly segmented formed then joined together, which is also disadvantageous as it increases the cost of manufacturing. This study proposes a hybrid cold-hot stamping method for the 1-piece door inner part to reduce cost. To design the stamping process, numerical simulation method is established by using the temperature-dependent mechanical properties of AA6016. The formability according to the hybrid cold-hot stamping method is evaluated using numerical analysis. The suitability of the proposed stamping method is then verified through the stamping tryout.

• Journal of Welding and Joining
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• v.33 no.6
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• pp.55-59
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• 2015

Self-piercing riveting (SPR) is a sheet-joining method that can be used for materials that are difficult or unsuitable for weld, such as aluminum alloys and other steel sheet metals. The increased application of lightweight materials has initiated many investigations into new SPR conditions for riveting dissimilar materials. However, buckling of the semi-tubular rivet occurs during the riveting of AHSS. In this study, a helical SPR was designed for the riveting of AHSS and Al-alloy. In addition, the reinforced helical SPR which has straight parts was designed. The riveting of AHSS and Al-alloy was simulated. Simulated results were verified by comparison with experimental ones.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.655-659
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• 2011

An ultrafine grained complex aluminum alloy was fabricated by an accumulative roll-bonding (ARB) process using dissimilar aluminum alloys of AA1050 and AA5052 and subsequently annealed. A two-layer stack ARB process was performed up to six cycles without lubricant at an ambient temperature. In the ARB process, the dissimilar aluminum alloys, AA1050 and AA5052, with the same dimensions were stacked on each other after surface treatment, rolled to the thickness reduction of 50%, and then cut in half length by a shearing machine. The same procedure was repeated up to six cycles. A sound complex aluminum alloy sheet was fabricated by the ARB process, and then subsequently annealed for 0.5h at various temperatures ranging from 100 to $350^{\circ}C$. The tensile strength decreased largely with an increasing annealing temperature, especially at temperatures of 150 to $250^{\circ}C$. However, above $250^{\circ}C$ it hardly decreased even when the annealing temperature was increased. On the other hand, the total elongation increased greatly above $250^{\circ}C$. The hardness exhibited inhomogeneous distribution in the thickness direction of the specimens annealed at relatively low temperatures, however it had a homogeneous distribution in specimens annealed at high temperatures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.88-91
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• 2006

Ultra-fine grained and high hardened Al sheet was obtained by Equal Channel Angular Pressing (ECAP). During this process the microstructure, the hardness and the texture of AA 1050 Al alloy sheet are changed by a severe shear deformation. The plastic strain ratio after the ECAP and subsequent heat-treatment condition was investigated in this study. It was found that the average r-value of the equal channel angular pressed and subsequent heat-treated specimen was 1.7 times higher than that of the initial Al sheet. This could be attributed to the various texture formations through the ECAP and subsequent heat-treatment of AA 1050 Aluminum alloy sheets.