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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
Fabrication of Bulk Amorphous Al Alloys by Plastic Deformation
Kim, Hyoung-Seop ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 419~425
Density Improvement of Sintered Preforms by the Cold Rotary Forging
Yun, Deok-Jae ; Im, Seong-Ju ; Choe, Seok-U ; Na, Gyeong-Hwan ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 426~431
This study is concerned with cold repressing of sintered preforms by the rotary forging process. An experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The effect of process variables and aspect ration of sintered preform on the densification behavior during the rotary repressing was studied by several mechanical test such as working force hardness distribution density and microstructures of the specimens. Since a higher densification can be achieved by applying the rotary repressing on presinted preforms it was successively demonstrated that the cold rotary powder forging is an effective operation to improve quality of P/M parts.
The Forming Characteristic of Rotary Swaging Process.
Im, Seong-Ju ; Yun, Deok-Jae ; Na, Gyeong-Hwan ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 432~438
The process variables i.e. the speed of forming, the ratio of thickness to diameter the shape of formed materials and the reduction of area were selected in order to study the process of the rotary swaging. It was found that the process variables affected the quality of products, i.e. the hardness the surface roughness and the degree of precision of products. Variation of hardness in deformed samples was mainly dependent on the reduction of area. Upon forming tubes applying the t/D ration higher than 1/10 led to the formation of defects on products which may be reduced by application of mandrels.
Experimental study on the severe deep drawing for complex cylindrical housing of STS 305 stainless steel
Kim, Doo-Hwan ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 439~444
Recently many automotive parts have been made with stainless steels by deep drawing processes, But there are various problems occurred in deep drawing works of stainless steels compared with low carbon steels. For the severe deep drawing of complex cylindrical housing optimum process planning is required to eliminate intermediate annealing improve shape accuracy and maintain surface integrity without drawing defects such as tears wrinkles and scratches or galling. Therefore in this study a sample process planning of the severe of the severe deep drawing process is applied to a complex cylindrical housing needed for a 6 multi-stepped deep drawing of type STS 305 . A series of experiments are performed to investigate optimum process variables such as drawing rate radius and clearance. Through experiments the variations of the thickness strain distribution and hardness distribution in each drawing step are observed. Also the effects of other factors on formability such as drawing oil, blank holding force and die geometry are examined and discussed.
A Study on the Improvement of Formability of Stainless Steel Sheets
Bae, Won-Byeong ; Heo, Byeong-U ; Kim, Ho-Yun ; Han, Jeong-Yeong ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 445~449
In order to obtain optimum process variables during the drawing of stainless steel sheets rectangular cup drawing tests were carried out with several technically available stainless steel sheets. As parameters on testing materials for die and punches lubrication and blank holding forces were selected. Testing parameters played an important role if the deformed material was thin. Effect of material properties on the deformation behaviors was also discussed by using testing parameters selected in this experiment. From the test results we suggest the appropriate conditions to be applicable to the actual manufacturing processes
High Temperature Deformation Behavior of Al 5083 Alloy Using Deformation Processing Maps
Ko, Byung-Chul ; Kim, Jong-Hyun ; Yoo, Yeon-Chul ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 450~458
The high temperature deformation behavior of Al 5083 alloy has been studied in the temperature range of 350 to 520
and strain rate range of 0.2 to 3.0/sec by torsion test. The strain rate sensitivity(m) of the material was evaluated and used for estabilishing power dissipation maps following the dynamic material model. These maps show the variation of efficiency of power dissipation(
=2m/(2m+1)) with temperature and strain rate. Hot restoration of dynamic recrystallization (DRX) was analyzed from the flow curve, deformed microstructure, and processing maps during hot deformation. Also, the effect of deformation strain on the efficiency of power dissipation of the alloy was analysed using the processing maps. Moreover relationship between the hot-ductility and efficiency of power dissipation of the alloy depending on thmperature and strain rate was studied using the Zener-Hollomon parameter(Z=
exp(Q/RT) It is found that the maximum efficiency of power dissipation for DRX in Al 5083 alloy is about 74.6 pct at the strain of 0.2. The strain rate and temperature at which the efficiency peak occurred in the DRX domain is found to be ∼0.1/sec and ∼450
Effect of Initial Textures on the Plane Strain Stretching
Bae, Seok-Yong ; Lee, Yong-Sin ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 459~464
Effect of the several initial textures such as random texture, rolling texture and cube texture, on the plane strain stretching was studied by interpretation of the finite element method. The calculation of yield locus indicated that the sheet oriented in the cube texture exhibits easy yielding on uniaxial stress state whereas the sheet having either a random or the rolling texture exhibits easy yielding on shear deformation. Upon stretching tests, the thickness strain at the center region contacting the punch was identical regardless of the initial textures while the dependence of the thickness strain on the initial texture was found in the other regions. In general punch loads required or the sheet with an initial cube texture was as expected from calculated yield locus, lower than those for the others.
Effect of the Alloying Elements in Ag-Cu-Zr-X Brazing Alloy on the Microstructure and the Bond Strength of
/Ni-Cr Steel Brazed Joint
Kim, Jong-Heon ; Yoo, Yeon-Chul ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 465~473
The effect of alloying elements of Ag-Cu-Zr-X brazing alloy on the microstructure and the bond strength of
brazed steel joint was investigated. The reaction layer,
)was formed at the interface of
steel joint by the redox reaction between alumina and Zr. The addition of An and Al to the Ag-Cu-Zr brazing alloy gave rise to changes in the thickness of the reaction product layer and the morphology of the brazement. Sn caused the segregation of Zr was decreased b Al the
layer formed at the Ag-Cu-Zr-Al alloy was thinner than that of
formed at the Ag-Cu-Zr-An alloy. The fracture shear strength was strongly dependent on the microstructure of the brazement. Brazing with Ag-Cu-Zr-Sn alloy resulted in a better bond strength than with Ag-Cu-Zr or Ag-Cu-Zr-Al alloy.
Domain Decomposition using Substructuring Method and Parallel Computation of the Rigid-Plastic Finite Element Analysis
Park, Keun ; Yang, Dong-Yol ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 474~480
In the present study a domain decomposition scheme using the substructuring method is developed for the computational efficiency of the finite element analysis of metal forming processes. in order to avoid calculation of an inverse matrix during the substructuring procedure, the modified Cholesky decomposition method is implemented. As obtaining the data independence by the substructuring method the program is easily paralleized using the Parallel Virtual machine(PVM) library on a work-station cluster connected on networks. A numerical example for a simple upsetting is calculated and the speed-up ratio with respect to various number of subdomains and number of processors. The efficiency of the parallel computation is discussed by comparing the results.
Evolution of Interfacial Microstructure in Alumina and Ag-Cu-Zr-Sn Brazing Alloy
Kim, Jong-Heon ; Yoo, Yeon-Chul ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 481~488
The active metal brazing was applied to bond Alumina and Ni-Cr steel by Ag-Cu-Zr-Sn alloy and the interfacial microstructure and reaction mechanism were investigated. Polycrystalline monoclinic
with a very fine grain of 100-150 nm formed at the alumina grain boundary contacted with Zr segregation layer at the interface. The
layer containing the inclusions and cracks were developed at the boundary of inclusion/
due to the difference in specific volume. The development of
at the interface was successfully explained by the preferential penetration of
at the interface was successfully explained by the preferential penetration of Zr atoms a higher concentration of oxygen and a high diffusion rate of Al ions into molten brazing alloy.
Design of roller path for spinning of cylindrical cups of aluminum sheet metal
Kim, Jong-Ho ; Park, Gyu-Ho ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 489~495
Spinning is a chipless forming method for producing axially symmetric parts by using axial-radial motions of a spinning roller. This process has still some advantages in such a view point that a variety of complex shapes which can not be formed in a press can be easily spun at a low cost although it is one of the oldest forming methods for spinning mainly cookware parts for a long time. This study is to investigate the optimum roller path in order to obtain the maximum spinnability in producing cylindrical cups of Aluminum(A1050-H16) sheet metal. Working conditions applicable to any size of blank were predetermined through preliminary spinning tests. 9 types of roller path were proposed and experiments were carried out. The modified involute curve was shown to give the maximum drawing ration and more uniform quality of spun cups as compared with other results of this study. in addition thickness distribution and dimensional accuracy of spun cups were examined and discussed.
A Study on the U-bending of Rectangular Hollow Tube by the Eccentric Extrusion and Bending Process
Kim, Jin-Hoon ; Jin, In-Tai ;
Transactions of Materials Processing, volume 7, issue 5, 1998, Pages 496~504
The eccentric extrusion and bending process for the forming of the curved rectangular hollow tube is newly developed. Generally the bending process of hollow tube is the secondary process followed by the extrusion process of the hollow tube from the round billet. So many defects such as wrinkling and the difference of wall thickness can be happened during the secondary bending process. In order to avoid the defects the new process named as "the eccentric extrusion and bending process" is suggested and applied to the U-bending of rectangular hollow tube. In this paper the kinematically admissible velocity field between the dies surface and the internal plug boundary surface s developed for the curving velocity. By the using of this curving velocity field the curvature of extruded products can be calculated with the parameters such as eccentricity dies length friction constant aspect ratio.