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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 23, Issue 8 - Dec 2014
Volume 23, Issue 7 - Nov 2014
Volume 23, Issue 6 - Oct 2014
Volume 23, Issue 5 - Aug 2014
Volume 23, Issue 4 - Jul 2014
Volume 23, Issue 3 - Jun 2014
Volume 23, Issue 2 - Apr 2014
Volume 23, Issue 1 - Feb 2014
Selecting the target year
A New Model for Predicting Width Spread in a Roughing Mill - Part I: Application to Dog-bone Shaped Inlet Cross
Lee, D.H. ; Lee, K.B. ; Hwang, S.M. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 139~144
DOI : 10.5228/KSTP.2014.23.3.139
In the current study, we present a new model for predicting width spread of a slab with a dog-bone shaped cross section during rolling in the roughing train of a hot strip mill. The approach is based on the extremum principle for a rigid plastic material and a three dimensional admissible velocity field. The upper bound theorem is used for calculating the width spread of the slab. The prediction accuracy of the proposed model is examined through comparison with the predictions from 3-D finite element (FE) process simulations.
A New Model for Predicting Width Spread in a Roughing Mill - Part II: Application to Flat Rolling
Lee, D.H. ; Lee, K.B. ; Hwang, S.M. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 145~150
DOI : 10.5228/KSTP.2014.23.3.145
Precision control of the slab is crucial for product quality and production economy in hot strip mills. The current study presents a new model for predicting width spread of a slab with a rectangular cross section during roughing. The model is developed on the basis of the extremum principle for a rigid plastic material and a three dimensional admissible velocity field. This model incorporates the effect of process variables such as the shape factor and the ratio of width to thickness. We compare the results of this model to 3-D finite element (FE) process simulations and also to results from a previous study.
Effects of Processing Routes on the Deformation Behavior of an AZ61 Mg Alloy by Half Channel Angular Extrusion(HCAE) using 3D Finite Element Analysis
Lee, S.I. ; Yoon, J.H. ; Kim, K.J. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 151~158
DOI : 10.5228/KSTP.2014.23.3.151
Half channel angular extrusion(HCAE) is the integration of equal channel angular extrusion(ECAE), which is a well-known severe plastic deformation(SPD) method, with conventional forward extrusion in order to increase the strain per pass and effectiveness of the grain refinement. In the current study, the effects of processing routes during HCAE(Routes A, B, and C) on the strain distribution of the specimens have been investigated for an AZ61 Mg alloy by using three-dimensional finite element analysis. Comparisons with the results from a multi-pass of ECAE are made.
Effect of Small Surface Defects in the Starting Material on Product Quality after Drawing
Nam, C.H. ; Lee, I.K. ; Lee, J.K. ; Joun, M.S. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 159~163
DOI : 10.5228/KSTP.2014.23.3.159
In the current study, the effect of small surface defects in the starting material including roughness, indentations, or scratches, which are perpendicular to the direction of drawing, on the product quality is investigated using the finite element method. An axisymmetric defect is assumed. Such defects are defined by a cylindrical defect area and two tapered regions connecting the defect area to the non-defective area of the material. Various conditions for these initial surface defects are considered, including defect depth, defect slope and defect length. To describe the plastic deformation of the defect in detail during the simulation, local remeshing is applied. Based on the finite element results, defect disappearance maps were generated. It was found that defect disappearance is significantly dependent on the defect depth and the defect length coupled with the defect slope.
Study of Tube Expansion to Produce Hair-Pin Type Heat Exchanger Tubes using the Finite Element Method
Hong, S. ; Hyun, H. ; Hwang, J. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 164~170
DOI : 10.5228/KSTP.2014.23.3.164
To predict the deformation and fracture during tube expansion using the finite element (FE) method, a material model is considered that incorporates the damage evolution due to the deformation. In the current study, a Rice-Tracey model was used as the damage model with inclusion of the hydrostatic stress term. Since OFHC Cu is not significantly affected by strain rate, a Hollomon flow stress model was used. The material parameters in each model were obtained by using an optimization method. The objective function was defined as the difference between the experimental measurements and FE simulation results. The parameters were determined by minimizing the objective function. To verify the validity of the FE modeling, cross-verification was conducted through a tube expansion test. The simulation results show reasonable agreement with the experiments. The design for a minimum diameter of expansion tube using the FE modeling was verified by a simplified tube expansion test and simulation results.
Analysis of the Homogenization of the Elastic Behavior for a Sheet with Sheared Protrusions using Hexahedral Mesh Coarsening
Lee, C.W. ; Yang, D.Y. ; Park, J.S. ; Kang, D.W. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 171~177
DOI : 10.5228/KSTP.2014.23.3.171
The current collector for the molten carbonate fuel cell (MCFC) which has sheared protrusions is manufactured by the three-stage forming process that integrates slitting, preforming and final forming. Due to the repetition of sheared protrusions, an effective simulation method is required to predict the mechanical behavior. In the current study, a sheet with sheared protrusions was assumed to be an orthotropic plate, which has the same length, width and height. FEM simulations were conducted to evaluate the homogenized properties of the current collector, which has 4 (longitudinal direction) x 4 (transverse direction) sheared protrusions. The simulation model was constructed using hexahedral mesh coarsening. From the verification examples, it was found that the proposed simulation method was efficient within reasonable accuracy. The calculated homogenized properties can be applied to the design of a stack for molten carbonate fuel cells and the prediction of mechanical behavior for other applications.
High Temperature Mechanical Properties of Continuous Cast and Extruded ZK60A Alloy
Ahn, B. ;
Transactions of Materials Processing, volume 23, issue 3, 2014, Pages 178~183
DOI : 10.5228/KSTP.2014.23.3.178
Continuous casting is a process where molten metal is solidified into a semi-finished billet on a large scale with either a rectangular or round cross section for subsequent processing. The use of continuous casting provides an opportunity for producing material on a practical industrial scale with lower cost than conventional casting. In the current study, the material was fabricated by continuous casting and subsequent extrusion. Tensile tests were conducted on continuous cast ZK60A after extrusion over a range of strain rates at temperatures from 473K to 623K. The alloy exhibits a quasi-superplastic behavior with a maximum recorded elongation of ~250% at 523K when tested with an initial strain rate of
. The experiments give a strain rate sensitivity exponent of 0.3~0.4 and an activation energy of 108 kJ/mol. From the current investigation, it was found that the high-temperature plastic flow of the ZK60A is controlled by a dislocation viscous glide mechanism.