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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of Materials Processing
Journal Basic Information
Journal DOI :
The Korean Society for Technology of Plasticity
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Volume & Issues
Volume 13, Issue 8 - Dec 2004
Volume 13, Issue 7 - Nov 2004
Volume 13, Issue 6 - Oct 2004
Volume 13, Issue 5 - Aug 2004
Volume 13, Issue 4 - Jul 2004
Volume 13, Issue 3 - Jun 2004
Volume 13, Issue 2 - Apr 2004
Volume 13, Issue 1 - Feb 2004
Selecting the target year
A Study on Initial Blank Design and Modification for Rectangular Case Forming with Extreme Aspect Ratio
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 307~318
DOI : 10.5228/KSPP.2004.13.4.307
Rectangular drawn case with extreme aspect ratio is widely used for electrical parts such as a lithium-ion battery container, semi-conductor case and so on. Additionally, from the recent trend towards miniaturization of the multi-functional mobile device, demands for rectangular case with the narrow width are increased. In this study, numerical and experimental approaches for the multi-stage deep drawing process have been carried out. Based on the research results of the width of 5.95mm model, finite element analysis for storage case of rectangular cup type was verified to the width of 4.95mm. Also, a series of manufacturing experiments for rectangular case is conducted and the deformed configuration of the rectangular drawn case are investigated by comparing with the results of the numerical analysis. And the modification of the initial blank is performed to minimize the trimmed material amount. By the application of the modified blank, the sound shape of the deformed parts is improved.
Thermal Behavior Analysis in Continuous Bloom Casting Mold
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 319~325
DOI : 10.5228/KSPP.2004.13.4.319
Continuous casting machine has been experienced a rapid development to increase productivity with high casting speed and to meet consumer's strict demands for high quality. However, because most of defects and cracks are initially formed in mold and grown into surface cracks during the post process, more specific and clear investigations upon heat transfer mechanism between mold and solidified shell are necessarily needed. In this study heat transfer coefficients which shows the characteristic of heat transfer mechanism are calculated with temperatures measured in bloom mold using optimal algorithm, and thermal analysis are investigated using the calculated heat transfer coefficients. Finally uniformity of solidified shell is investigated for high carbon steel, 0.187%C from thermal analysis.
Maskless Fabrication of the Silicon Stamper for PDMS Nano/Micro Channel
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 326~333
DOI : 10.5228/KSPP.2004.13.4.326
The nanoprobe based on lithography, mainly represented by SPM based technologies, has been recognized as a potential application to fabricate the surface nanosctructures because of its operational versatility and simplicity. However, nanoprobe based on lithography itself is not suitable for mass production because it is time a consuming method and not economical for commercial applications. One solution is to fabricate a mold that will be used for mass production processes such as nanoimprint, PDMS casting, and others. The objective of this study is to fabricate the silicon stamper for PDMS casting process by a mastless fabrication technique using the combination of nano/micro machining by Nanoindenter XP and KOH wet etching. Effect of the Berkovich tip alignment on the deformation was investigated. Grooves were machined on a silicon surface, which has native oxide on it, by constant load scratch (CLS), and they were etched in KOH solutions to investigate chemical characteristics of the machined silicon surface. After the etching process, the convex structures was made because of the etch mask effect of the mechanically affected layer generated by nanoscratch. On the basis of this fact, some line patterns with convex structures were fabricated. Achieved groove and convex structures were used as a stamper for PDMS casting process.
Adaptive Delaunay Mesh Generation Technique Based on a Posteriori Error Estimation and a Node Density Map
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 334~341
DOI : 10.5228/KSPP.2004.13.4.334
In this study, a remeshing algorithm adapted to the mesh density map using the Delaunay mesh generation method is developed. In the finite element simulation of forging process, the numerical error increases as the process goes on because of discrete property of the finite elements and distortion of elements. Especially, in the region where stresses and strains are concentrated, the numerical error will be highly increased. However, it is not desirable to use a uniformly fine mesh in the whole domain. Therefore, it is necessary to reduce the analysis error by constructing locally refined mesh at the region where the error is concentrated such as at the die corner. In this paper, the point insertion algorithm is used and the mesh size is controlled by using a mesh density map constructed with a posteriori error estimation. An optimized smoothing technique is adopted to have smooth distribution of the mesh and improve the mesh element quality.
Form-Joining Process with the Aid of Adhesive for Joining of Sheet Metal Pair
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 342~349
DOI : 10.5228/KSPP.2004.13.4.342
The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair. The joining strength from the process ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of an adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, and before it cures the pair is clinched to cause the geometric constraint in the form of a protrusion. In order to reduce the forming load and the height of protrusions, a new die and punch set with a very small clearance is devised to reduce the depth of drawing and the forming load. Taguchi method is employed to find the optimal values of design parameters. To implement each case of the orthogonal array, the finite element method is used. The experiments show that in the tensile-shear test, the bonding strength of the new form-joining process with an epoxy adhesive is approximately the same as that of the resistance spot welding; and in comparison with the other two form-joining processes with an epoxy adhesive, the height of protrusions is reduced by more than 65 percent and the forming load by 50 percent.
Effects of Alloying Elements and Pro-eutectoid Ferrite on Mechanicl Properties in Medium Carbon Steels
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 350~358
DOI : 10.5228/KSPP.2004.13.4.350
The effects of alloying elements on microstructural features and mechanical properties in 0.55%C medium carbon steels were investigated. The samples were austenitized at 105
for 30min. followed by quenching in a salt bath in the temperature range of 500 ~
. The addition of Cr resulted in the decrease of the volume fraction of pro-eutectoid ferrite and interlamellar spacing in pearlite and the increase of strength. However, the addition of B caused the increase of the volume fraction of pro-eutectoid ferrite. Reduction of area and Charpy impact values were influenced by the combined effect of microstructural features, such as the volume fraction of pro-eutectoid ferrite, interlamellar spacing and the thickness of lamellar cementite in pearlite.
Design of Hexagonal Fitting Nut Preform Considering a Ductile Fracture
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 359~364
DOI : 10.5228/KSPP.2004.13.4.359
In the multi-stage former, a manufacture of hexagonal fitting nut was generated in a defective products about 70∼80% in the industry field. Products generated in defects manufactured to be a machining about 60%. Additional process increased a product cost and decreased a product rate. Therefore, it is important to predict and design a preform reducing defective products in the early stage of process design. So in the study Defects for manufacturing hexagonal fitting nut verified a cause through the finite element simulation. To reduce a defective generation. a preform designed and a designed preform verified through the finite element simulation. In conclusion, a generated defects when a hexagonal fitting nut manufactured should reduce if a round dimension of preform reduced and a part of opposition angle distributed in plenty a volume.
Plastic Strain Ratio and Planar Anisotropy of AA5182/Polypropylene/AA5182 Sandwich Sheets
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 365~373
DOI : 10.5228/KSPP.2004.13.4.365
The sheet formability of single AA5182 sheets and sandwich sheets comprising of AA5182/polypropylene/AA5182 (AA/PP/AA) was studied. Rolling without lubrication and subsequent recrystallization annealing led to the formation of favorable ｛111｝//ND fiber textures in AA5182 sheets, which provided a higher plastic strain ratio of
value of 1.58 was obtained in the AA/PP/Ah sandwich sheet sample. Furthermore, a proper combination of the sample direction of the upper and lower skin sheet gave rise to an optimization of the sheet formability of the sandwich sheets.
A Study on Deformation Behavior of the Grain-Size Controlled Rheology Material by Using Nanoindenter and AFM
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 374~381
DOI : 10.5228/KSPP.2004.13.4.374
In this study, the deformation behavior of semi-solid Al-Si alloy was investigated by nanoindenter as a part of the research on the surface crack behavior in thixoformed automobile component. The microstructure of semi-solid Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of semi-solid aluminium alloy were investigated through the nano-indentation experiments and the AFM observation. In addition, mechanical properties of each region were investigated and compared with each other.
Analysis on Inhomogeneous Textures Developed in Aluminum AA 1050 Sheets during Continuous Confined Strip Shearing
Transactions of Materials Processing, volume 13, issue 4, 2004, Pages 382~387
DOI : 10.5228/KSPP.2004.13.4.382
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
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.