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Anisotropic Properties of Stainless Steel – Clad Aluminum Sheet
Daeyong Kim,Bum Kyu Hwang,Young Seon Lee,Ji Hoon Kim,Min-Joong Kim 한국소성가공학회 2010 기타자료 Vol.2010 No.6
The production of a stainless steel - clad aluminum sheet by the cold rolling process is a more efficient and economical approach compared with the other types of processes utilized for the production of such sheets. Because both the stainless steel and aluminum sheets show the highly anisotropic behavior, it is necessary to investigate anisotropic properties of clad sheets for the design of process. In this paper, to investigate the anisotropic properties of stainless steel ? clad aluminum sheet, two kinds of clad sheets were considered: STS439/AA3003 and STS439/AA1050/STS304 clad sheets. The uni-axial tension tests at 0, 45 and 90 degrees for the rolling direction were performed to obtained yield stresses and R values. The strain ratio at balanced biaxial tension state was measured from compression disk test. In order to describe the anisotropic behavior of the clad sheet, nonquadratic anisotropic yield function Yld2000-2d was utilized.
모재의 방향성에 따른 마찰교반용접 판재의 성형성에 관한 실험적 연구
김대용(Daeyong Kim),이원오(Wonoh Lee),김준형(Junehyung Kim),Chongmin Kim,정관수(Kwansoo Chung) 한국소성·가공학회 2009 소성가공 : 한국소성가공학회지 Vol.18 No.1
In order to investigate the formability of friction stir welded(FSW) tailor welded blanks(TWB) with respect to the base material’s directional combination, aluminum alloy AA6111-T4 sheets were welded with three different conjoining types: RD-RD, TD-RD and TD-TD. Here, RD and TD represent rolling and transverse directions, respectively. For experimental formability study, three tests with gradual complexity were performed: the simple tension test with various weld line directions for uni-axial elongation, the hemisphere dome stretching test for biaxial stretching and the cylindrical cup deep drawing test. As a result, all three forming tests showed that RD-RD type samples exhibited the best formability, while TD-TD type sheets showed the least formability performance.
Improving the room-temperature formability of a magnesium alloy sheet by texture control
Kim, Se-Jong,Lee, Changjoon,Koo, Jamyeong,Lee, Jinwoo,Lee, Young-Seon,Kim, Daeyong Elsevier Sequoia 2018 Materials science & engineering Structural materia Vol.724 No.-
<P><B>Abstract</B></P> <P>In this study, a sheet of AZ31 magnesium alloy was compressed by 3%, 5%, and 7% along the in-plane direction while simultaneously applying a compressive load in the normal direction (ND) to avoid buckling during compression. Changes in the microstructure and texture were measured after annealing. Recrystallization and grain growth occurred in grains with higher deformation energy than surrounding grains after annealing at 300 °C. The area fraction of the orientations for which the <I>c</I>-axis and transverse direction (TD) are parallel (twinned grains) and the orientations with an angle between the <I>c</I>-axis and ND ranged from 30° to 60°, a situation that is favorable for accommodating strain along the thickness direction by slip and detwinning, increased compared to the as-received specimen. The favorable orientations tended to increase as the compressive strain increased. As a result, the formability for the bi-axial stretch mode is higher in the specimen annealed at 300 °C for 60 min after 7% compression than in the as-received specimen.</P>
Experimental study on forming behavior of high-strength steel sheets under electromagnetic pressure
Kim, Daeyong,Park, Hyeon Il,Lee, Jinwoo,Kim, Ji Hoon,Lee, Myoung-Gyu,Lee, Youngseon Professional Engineering Publishing Ltd. 2015 Proceedings of the Institution of Mechanical Engin Vol. No.
<P>To experimentally investigate the forming behavior of automotive high-strength steel sheets under electromagnetic pressure, three high-strength steel sheets (DP780, DP980, and CP1180) were freely formed into hemi-elliptical protrusions. The experiments were performed using a spiral flat coil and open-cavity die. Aluminum driver plates were utilized for improving the forming efficiency. The forming behavior was investigated by evaluating characteristics such as peak height, limit height, and springback angle for various charge voltages. The effect of the aluminum driver plate on the forming behavior of the high-strength steel sheet was also observed.</P>
Kim, Daeyong,Lee, Myoung-Gyu,Kim, Chongmin,Wenner, Michael L.,Wagoner, Robert H.,Barlat, Frederic,Chung, Kwansoo,Youn, Jae Ryoun,Kang, Tae Jin 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.6
In order to present better prediction capability in computational analysis, mechanical properties of the dualphase high strength steel have been characterized especially for anisotropy as well as the Bauschinger and transient behavior. As for the anisotropy, the non-quadratic anisotropic yield function Yld2000-2d has been utilized and its material parameters have been obtained using the uni-axial tension tests as well as the hydraulic bulge test. To measure the hardening behavior including the Bauschinger and transient behavior, a newly developed test method has been applied for the uni-axial tension/compression and compression/tension tests, in which solid blocks along the both sides of the sheet specimen prevent buckling. From the tension/compression curves, the equations to describe isotropic and kinematic hardening behavior have been obtained. The modified Chaboche model has been confirmed to well represent the hardening behavior including the Bauschinger and transient behavior.