Analysis on Void Closure Behavior during Hot Open Die Forging

2007 ◽  
Vol 26-28 ◽  
pp. 69-72 ◽  
Author(s):  
Young Seon Lee ◽  
Y.C. Kwon ◽  
Yong Nam Kwon ◽  
Jung Hwan Lee ◽  
S.W. Lee ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Effective Strain ◽  
Fem Analysis ◽  
Void Closure ◽  
X Ray ◽  
Die Forging ◽  
Before And After ◽  
Measured Flow ◽  
Flow Stress Data ◽  
Open Die Forging

Internal voids have to be eliminated for defect-free in some open die forging. The FEM analysis is performed to investigate the overlap defect of cast ingots during cogging stage. The measured flow stress data were used to simulate the cogging process of cast ingot using the practical material properties. Also the numerical analysis of void closure is performed by using the DEFORMTM-3D. The calculated results of void closure behavior are compared with the measured results before and after upsetting, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the void closure were estimated into effective strain of 0.6 by the comparison of practical experiment and numerical analysis.

FEM Analysis of Void Closure Behaviour during Open Die Forging of Rectangular Billets

2006 ◽  
Vol 77 (2) ◽  
pp. 116-121 ◽  
Author(s):  
Myung Sik Chun ◽  
Chester J. Van Tyne ◽  
Young Hoon Moon
Keyword(s):  
Fem Analysis ◽  
Void Closure ◽  
Die Forging ◽  
Open Die Forging

Analysis on Void Closure Behavior during Hot Open Die Forging

2007 ◽  
pp. 69-72
Author(s):  
Young Seon Lee ◽  
Y.C. Kwon ◽  
Yong Nam Kwon ◽  
Jung Hwan Lee ◽  
S.W. Lee ◽  
...  
Keyword(s):  
Void Closure ◽  
Die Forging ◽  
Open Die Forging

scholarly journals Experimental and FEM Analysis of Void Closure in the Hot Cogging Process of Tool Steel

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 538 ◽  
Author(s):  
Marcin Kukuryk
Keyword(s):  
Hydrostatic Stress ◽  
Effective Strain ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Fem Analysis ◽  
Experimental Tests ◽  
Reduction Ratio ◽  
Compression Process ◽  
Void Closure ◽  
Axial Defects

In the present study, a new complex methodology for the analysis the closure of voids and a new forging system were developed and tested. The efficiency of the forging parameters and the effective geometric shapes of anvils to improve void closure were determined. A new cogging process provided a complete closure of an ingot’s axial defects, as confirmed by experimental tests. The evolution behavior of these defects with different sizes was investigated during the hot cogging process by means of the professional plastic forming software Deform-3D. A comprehensive procedure was developed using the finite-element method (FEM) for the three-dimensional cogging process and laboratory experimentation to predict the degree of void closure. The hot multi-pass cogging process was used to eliminate void defects in the forgings so as to obtain sound products. In the compression process, the effects of the reduction ratio and forging ratio, the void size, and the types of anvil were discussed to obtain the effective elimination of a void. For the purpose of the assessment of the effectiveness of the void closure process, the following indices were introduced: the relative void volume evolution ratio, the relative void diameter ratio, and the internal void closure evaluation index. Moreover, the void closure process was assessed on the basis of stress triaxiality, hydrostatic stress, forging ratio, value of local effective strain around the void, and critical reduction ratio. The results of this research were complemented by experiments predicting the formation of fractures in the regions near the void and in the volume of the forging in the course of the cogging process. The comparison between the predicted and the experimental results showed a good agreement.

Investigation of void closure in open-die forging considering changing load directions

2019 ◽  
Vol 13 (6) ◽  
pp. 703-711
Author(s):  
Paul Hibbe ◽  
Martin Wolfgarten ◽  
Gerhard Hirt
Keyword(s):  
Void Closure ◽  
Die Forging ◽  
Open Die Forging

scholarly journals Analysis of Void Closure during Open Die Forging Process of Large Size Steel Ingots

2016 ◽  
Vol 716 ◽  
pp. 579-585 ◽  
Author(s):  
Nathan Harris ◽  
Davood Shahriari ◽  
Mohammad Jahazi
Keyword(s):  
Strain Rate ◽  
High Strength Steel ◽  
Volumetric Strain ◽  
High Strength ◽  
Material Model ◽  
Void Closure ◽  
Forging Process ◽  
Large Size ◽  
Die Forging ◽  
Open Die Forging

Large size forged ingots, made of high strength steel, are widely used in aerospace, transport and energy applications. The presence of internal voids in the as-cast ingot may significantly affect the mechanical properties of final products. Thus, such internal defects must be eliminated during first steps of the open die forging process. In this paper, the effect of in-billet void positioning on void closure throughout the ingot breakdown process and specifically the upsetting step in a large ingot size steel is quantitatively investigated. The developed Hansel-Spittel material model for new high strength steel is used in this study. The ingot forging process (3D simulation) was simulated with Forge NxT 1.0® according to existing industrial data. A degree of closure of ten virtual existing voids was evaluated using a semi-analytical void closure model. It is found that the upsetting process is most effective for void closure in core regions and central upper billet including certain areas within the dead metal zone (DMZ). The volumetric strain rate is determined and two types of inertial effects are observed. The dependence of void closure on accumulated equivalent deformation is calculated and discussed in relation to void in-billet locations. The original combination of information from both relative void closure and the volumetric strain rate provides a way to optimize the forging process in terms of void elimination.

Optimization of open die forging of round shapes using FEM analysis

2006 ◽  
Vol 172 (1) ◽  
pp. 88-95 ◽  
Author(s):  
S.K. Choi ◽  
M.S. Chun ◽  
C.J. Van Tyne ◽  
Y.H. Moon
Keyword(s):  
Fem Analysis ◽  
Die Forging ◽  
Open Die Forging

Sensitivity Analysis of Process Parameters for Developing an Improved Open Die Forging Process

2014 ◽  
Vol 622-623 ◽  
pp. 231-238
Author(s):  
Yu Feng Cheng ◽  
Xiao Guang Yang ◽  
Qi Lu ◽  
Chao Voon Samuel Lim ◽  
Ai Jun Huang
Keyword(s):  
Sensitivity Analysis ◽  
Process Parameters ◽  
Effective Strain ◽  
Hot Forging ◽  
Forging Process ◽  
Analysis Process ◽  
Die Forging ◽  
Experiment Method ◽  
Experimental Process ◽  
Open Die Forging

Open die hot forging has a wide industrial application on deforming ingot into billet with desired dimension and qualified internal microstructure. An example open die forging process of Ti-6Al-4V ingot is selected herein. A 3D FE-based numerical method was used to investigate the open die forging process with respect to the real working conditions. The simulation results were validated by the collected experimental process parameters from the forging system. Moreover, design of experiment method is adopted regarding the variation of process parameters to reveal the effects of critical factors on product deformation and quality characteristics. Results show that the process parameters including press speed, feed and reduction has significant effect on the workpiece deformation and effective strain which represents the forged billet formability and quality. Improved process parameters method is suggested with respect to the experienced benchmark based on the sensitivity analysis. Keywords: Open die forging; Ti-6Al-4V alloy; Sensitivity analysis; Process parameter; Numerical simulation;

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

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