Calculation of Isothermal Flow Stress by the Combination of FEM and a Simple Compression Test.

Kada, Osamu; Miki, Tsuneharu; Toda, Masahiro; Osakada, Kozo

doi:10.1299/kikaic.64.4914

Cited by 2 publications

(5 citation statements)

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“…Flow curves shown in these figures represent those under isothermal condition, which are obtained by inverse analysis coupled with thermomechanical FE analysis proposed in this paper. Flow curves obtained by Kada's approach 14) are also shown in these figures as references. It is clearly shown that typical flow curves of metal under dynamic recrystallization are obtained by the proposed method, which cannot be obtained only by compensation for an equivalent strain by FE analysis, 14) where fluctuation in flow stress can be seen even at a larger strain when the metal is under perfect dynamic recrystallization.…”

Section: Flow Curve and Its Rate Sensitivitymentioning

confidence: 99%

“…Flow curves obtained by Kada's approach 14) are also shown in these figures as references. It is clearly shown that typical flow curves of metal under dynamic recrystallization are obtained by the proposed method, which cannot be obtained only by compensation for an equivalent strain by FE analysis, 14) where fluctuation in flow stress can be seen even at a larger strain when the metal is under perfect dynamic recrystallization. At a glance, the difference between the flow stress values obtained by Kada's approach and our proposed method may not be significantly large, but this difference is crucial from the metallurgical viewpoint.…”

Section: Flow Curve and Its Rate Sensitivitymentioning

confidence: 99%

“…5, but this steady-state value could not be obtained by the conventional approach. 14) Flow curves for different specimen sizes are shown in Fig. 10.…”

Section: Flow Curve and Its Rate Sensitivitymentioning

confidence: 99%

“…10,11) Although experimental facilities developed in these investigations can reduce inhomogeneous distributions of temperature and plastic deformation, it is impossible to realize ideal uniaxial deformation and uniform temperature distribution in the hot compression test of bulk metal. Several approaches for compensating inhomogeneous plastic deformation and temperature distributions are proposed [12][13][14] with aims to derive the flow curve from the hot compression test. Inhomogeneous plastic deformation in the hot compression test can be compensated by FE analysis, but, in order to estimate the flow curve, there is a need to introduce an average amount of strain 12,14) from distributed plastic strains of the workpiece.…”

Section: Introductionmentioning

confidence: 99%

“…Several approaches for compensating inhomogeneous plastic deformation and temperature distributions are proposed [12][13][14] with aims to derive the flow curve from the hot compression test. Inhomogeneous plastic deformation in the hot compression test can be compensated by FE analysis, but, in order to estimate the flow curve, there is a need to introduce an average amount of strain 12,14) from distributed plastic strains of the workpiece.…”

Section: Introductionmentioning

confidence: 99%

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Flow Curve Determination for Metal under Dynamic Recrystallization Using Inverse Analysis

Yanagida

Liu

2003

Mater. Trans.

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A new method for determining flow curves of hot metal under dynamic recrystallization is proposed in this paper. Thermomechanical finite element analysis of a tool and a workpiece under hot compression is used to evaluate the upsetting force obtained by an experiment, as a function of the distributed flow stress of the workpiece. In order to compensate the effect of inhomogeneous distributions of deformation and temperature on the flow curve, inverse analysis for calculating coefficients in a flow stress curve under dynamic recrystallization is coupled with the thermomechanical finite element analysis. The discrepancy in upsetting force between the experiment and thermomechanical finite element analysis is used as an error estimator in the inverse analysis. A new regression formula of the flow curve, which includes four independent parameters, is introduced. It can express the flow curve of hot metal under dynamic recrystallization as well as dynamic recovery and work hardening. Also, four independent parameters included in the proposed formula have clear physical meanings. The proposed method is applied to the hot compression test of plain carbon steel at elevated temperatures. Flow curves are successfully determined for diversified conditions of strain rate and forming temperature. From the determined parameters of the flow curve by the proposed inverse analysis method, it can be concluded that 1) the critical strain for the onset of dynamic recrystallization is dependent on strain rate as well as temperature, 2) the stain rate sensitivity of m ¼ 0:13 is acceptable for plain carbon steel under testing conditions, and 3) the temperature sensitivity A is approximately 3000-3600 [K À1 ]. Through investigation, it has become clearer that an accurate flow curve can be determined by the proposed method. In addition to a quantitative description of the flow curve as a function of strain, strain rate and temperature, metallurgical parameters such as the critical strain for the onset of dynamic recrystallization and steady-state stress could also be estimated directly by the proposed method.

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Section: Flow Curve and Its Rate Sensitivitymentioning

confidence: 99%

Section: Flow Curve and Its Rate Sensitivitymentioning

confidence: 99%

“…5, but this steady-state value could not be obtained by the conventional approach. 14) Flow curves for different specimen sizes are shown in Fig. 10.…”

Section: Flow Curve and Its Rate Sensitivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Flow Curve Determination for Metal under Dynamic Recrystallization Using Inverse Analysis

Yanagida

Liu

2003

Mater. Trans.

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Computer simulation for prediction of thermal distortion of JIS ADC12 flat-shape die-casting

Yamagata

Kurokawa

Tanikawa³

et al. 2014

Transactions of the JSME (In Japanese)

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A computer simulation method to predict the thermal distortion value of a high-pressure die cast part was investigated. The evaluated product was a flat-shape JIS ADC12 part. The actual distortion value of the part was measured by an optical 3D digitizer and it was compared with the predicted distortion value. In this method, the initial temperature distribution of the part was determined by casting simulation. The thermal distortion value during cooling was calculated by FEM analysis. The stress-strain relation was approximated by the elastic-perfectly plastic material model including the temperature dependence of the yield strength. It was found that the heat-transfer coefficient between the die and the injected molten metal is a critical factor to implement an accurate FEM simulation in the casting simulation. The heat-transfer coefficient value was accessed and confirmed using the temperature distribution measured by a thermo camera. The distortion values of the actual part optically measured as a function of the curing time well coincided with the simulated value. It was concluded that the method can predict the distortion within a practically accepted preciseness.

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Calculation of Isothermal Flow Stress by the Combination of FEM and a Simple Compression Test.

Cited by 2 publications

References 0 publications

Flow Curve Determination for Metal under Dynamic Recrystallization Using Inverse Analysis

Flow Curve Determination for Metal under Dynamic Recrystallization Using Inverse Analysis

Computer simulation for prediction of thermal distortion of JIS ADC12 flat-shape die-casting

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