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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Transactions of Materials Processing
Journal Basic Information
Journal DOI :
The Korean Society for Technology of Plasticity
Editor in Chief :
Volume & Issues
Volume 7, Issue 6 - Dec 1998
Volume 7, Issue 5 - Oct 1998
Volume 7, Issue 4 - Aug 1998
Volume 7, Issue 3 - Jun 1998
Volume 7, Issue 2 - Apr 1998
Volume 7, Issue 1 - Feb 1998
Selecting the target year
Thermal Properties of Al-Ni-Y Alloy Amorphous Ribbons and High Temperature Deformation Behavior of Al-Ni-Y Alloy Extrudates Fabricated with Amorphous Ribbons
Ko, Byung-Chul ; Yoo, Yeon-Chul ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 333~339
Hot torsion tests were conducted to investigate the high temperature deformation behavior of
alloy extrudates fabricated with amorphous ribbons. The powder metallurgy routes, hot pressing and hot extrusion were used to fabricate the extrudates. Thermal properties of amorphous ribbons with different thickness as a function of aging temperature were studied by thin film x-ray dif-fraction (XRD) and differential scanning calorimetry(DSC). The Al phase crystallite firstly formed in the amorphous ribbons and its crystallization temperature(
During the processings of consolidation and extrusion, nano-grained structure(~100 nm) was formed in the Al85Ni10Y5 alloy extrudates. The as-extrudated Al85Ni10Y5 alloy and the
alloy annealed at 250
for 1 hour showed a flow curve of DRV(dynamic recovery) during hot deformation at 400-550
. On the other hand, the
alloy annealed at 400
for 1 hour showed a flow curve of DRX(dynamic recrys-tallization) during hot deformation at 450-500
. Also the flow stress and flow strain of the
alloy extrudate annealed at 400
were higher than those at 250
An Upper Bound Analysis for the Twisting Phenomenon of Extrusion
Kim, Han-Bong ; Jin, In-Tai ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 340~346
A kinematically admissible velocity field is developed for the analysis of twisting of the extruded products with elliptical shapes from round billet. The twisting of extruded product is caused by the lin-early increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product in creases with the die twisting angle, the aspect ratio of product the friction condition, the reduction of area, and decreases with the die length.
Elastic Finite Element Analysis of the Cold Forging Dies Prestressed by Shrinkage Rings
Seo, Dae-Yun ; Lee, Min-Cheol ; Jeon, Man-Su ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 347~353
A new approach of elastic finite element to die stress analysis in forging is presented in this paper. The die set analysis problem is formulated by considering contact problems under both mechanical and thermal loads. In the approach, amount of shrink fit is controlled by thermal load i.e., temperature difference between die insert and shrink fits. The loading conditions are extracted automatically from a forging simulator. The predicted solution is compared with analytical one and it has been shown that the predicted results are in excellent agreement with the analytical ones. An application example is given, which was found in a cold forging company.
Forming Characteristics of Laser Welded Tailored Blanks III : Stretch Forming Characteristics
Park, Gi-Cheol ; Han, Su-Sik ; Jin, Jo-Gwan ; Gwon, O-Jun ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 354~363
In order to analyze the stretch forming characteristics of tailored blanks, laser welded blanks of different thickness and strength combinations were prepared and stretching tests were done. The stretching formability of laser welded blanks was reduced as increasing the deformation restraining force (
) ratio between two welded sheets. Weld line movement was attributed to strain concentration at weaker sheets and resulted in fracture at weaker sid, so that fracture could be predicted by the forming limit of the weak sheet. In the case of a welded blank with the similar deformation restraining force rations between two welded sheets, crack occurred at weld and its forming limit was about 15% less than the base sheet. The effects of lubrication and weld line position on stretch-ing formability were also investigated by experiments. Lower friction did not always give better formability for tailored blanks. Stretching formability was observed to be improved as increasing the area of weak sheet.
Finite Element Analysis of Extrusion Process in Semi-Solid State
Hwang, Jae-Ho ; Go, Dae-Cheol ; Min, Gyu-Sik ; Kim, Byeong-Min ; Choe, Jae-Chan ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 364~374
It is the objective of this study to analyze the effect of various process variables on the quality of extruded product and extrusion force for semi-solid extrusion of Al2024 with solid phase structure of globular type by the finite element method. Process variables are initial solid fraction, ram speed, semi-angle of die, and reduction in area. The results of experiment are compared with those of simulation in order to verify the usefulness of the developed finite element program. The flow and deformation of semi-solid alloy are analyzed by coupling by coupling the deformation of porous skeleton and the flow of liquid phase. It is also assumed that initial solid fraction is homogeneous.
Finite Element Analysis for Extrusion of Hollow Shaped Section Through Square Die
Lee, Chun-Man ; Lee, Seung-Hun ; Jo, Jong-Rae ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 375~381
This paper presents development of finite element simulation program and analysis of hot extrusion through square dies with a mandrel. The design of extrusion dies is still an art rather than science. Die design for a new extrusion process is developed from through in-plant trials. In the present paper, a three-dimensional steady-state finite element simulation program is developed. Steady-state assumption is used for both the analyses of deformation and temperature. The developed program is effectively used to simulate hollow extrusion of several sections. Distributions of temperature effective strain rate, mean strain rate and mean stress are studied for an effective design of extrusion dies.
Stamping Analysis and Die Design of Laser Welded Automotive Body
Kim, Heon-Young ; Shin, Yong-Seung ; Kim, Koan-Hoi ; Cho, Won-Seok ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 382~392
Computer simulations and test trials were carried out to obtain the optimal stamping conditions of the die design of the laser welded automotive body. The stamping process including gravity deflection bead calibration binder wrap, forming and spring back was simulated and compared with the results obtained from test trials. The production variables were determined from a preliminary operation and they were investigated in the simulation and the test trials. The formability was tested under the various conditions, such as the initial position of blank, blank holding force, corner radius and the shape of drawbead. Sound products without fracture, wrinkling and excessive weldline movement were produced by applying results obtained this investigation.
Experimental Study on Minimizing Wall Thickness Thinning for Deep Drawing of Circular Shells
Kim, Doo-Hwan ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 393~399
For minimizing wall thickness thinning of circular shells, a new stamping technology, the deep draw-ing process combined with ironing is approached and investigated. The design requirements for the deep drawing shells are to keep the optimum wall thickness with max. 10 percent thickness thinning of the initial blank thickness, to make uniform thickness strain distribution for the wall of circular shell and to improve the shape accuracy for the roundness and concentricity. In order to check the validity and effectiveness of proposed work, a sample process design is applied to a circular shell needed for a 4multi-stepped deep drawing. Through experiments, the variations of the thickness strain distribution in each drawing process are observed. Also a series of experiments are performed to investigate optimum process variables such as the geometry of tooling, radius and drawing rate. In particular, the advantage of current approach with ironing is shown in contrast to the conventional deep drawing process. From the results of proposed method, the optimum value of process variables are obtained, which contribute more uniform thickness strain distribution and better quality in the drawn product.
Study on Flash Weldability and Formability in Steel Sheets by Tailor Welded Blank
Choe, Mun-Il ; Min, Gyeong-Bok ; Gang, Seong-Su ;
Transactions of Materials Processing, volume 7, issue 4, 1998, Pages 400~406
The press formability analysis of welding parts was studied in the current work by the tailor welded blank. The press formability was tested by means of the flash weldability and the formability for two kinds of materials (SPCC & S35C). The results indicate that SPCC & S35C steel sheets showed good weldability and formability after an optimum welding conditions. The independent operation variables were characterized by strength of welding parts, deformation after the welding, press formability of welding parts and productibility of welding. The weldability and the quality of welding parts of the flashed SPCC steel sheet was superior to those of the S35C steel sheet, since a higher carbon content in steel sheet led to a higher hardness. The experimental results were discussed by the evaluation of the results obtained from tensile test, hardness test, micro-structure and V bending test.