scholarly journals Mathematical Modeling of Single Peak Dynamic Recrystallization Flow Stress Curves in Metallic Alloys

10.5772/34445 ◽  
2012 ◽  
Author(s):  
R. Ebrahimi ◽  
E. Shafiei
2009 ◽  
Vol 30 (6) ◽  
pp. 1939-1943 ◽  
Author(s):  
Zhipeng Zeng ◽  
Stefan Jonsson ◽  
Hans Jørgen Roven ◽  
Yanshu Zhang

Author(s):  
E. Shafiei ◽  
R. Ebrahimi

In this study a new constitutive equation, using the extrapolation of dynamic recovery (DRV) flow stress curve and kinetic equation for dynamic recrystallization (DRX), has been developed. This model is expressed in terms of characteristic points such as critical stress, critical strain, DRX steady state stress, and DRV saturation stress. Moreover, this analysis was done for the stress-strain curves under hot working condition for Ti-IF steel, but it is not dependent on the type of material and can be extended for any condition that a single peak dynamic recrystallization occurs. The results indicate that the stress-strain curves predicted by this model are in a good agreement with experimentally measured ones at all deformation conditions.


Author(s):  
Zhipeng Pan ◽  
Yixuan Feng ◽  
Xia Ji ◽  
Steven Y. Liang

Thermal mechanical loadings in machining process would promote material microstructure changes. The material microstructure evolution, such as grain size evolution and phase transformation could significantly influence the material flow stress behavior, which will directly affect the machining forces. An analytical model is proposed to predict cutting forces during the turning of AISI 4130 steel. The material dynamic recrystallization is considered through Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The explicit calculation of average grain size is provided in an analytical model. The grain size effect on the material flow stress is considered by introducing the Hall-Petch relation into a modified Johnson-Cook model. The cutting forces prediction are based on Oxley’s contact mechanics with consideration of mechanical and thermal loads. The model is validated by comparing the predicted machining forces with experimental measurements.


2012 ◽  
Vol 430-432 ◽  
pp. 1294-1297
Author(s):  
Zhi Min Zhang ◽  
Yong Biao Yang ◽  
Xing Zhang

The flow stress behavior of nanometric Al2O3 particulate reinforced Al alloy composites were investigated using thermal simulation machine Gleeble-1500. Microsturctural analysis were carried out on optical microscopy. The results showed that the flow stress increased with increasing strain rate and decreased with decreasing temperature. Dynamic recovery and dynamic recrystallization occurred during hot compression of the Al composites. The grain size increased with increasing temperature (590k-710k) and decreased at 750k due to dynamic recrystallization. The grain size decreased with increasing strain rates at 750k.


2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qiang Fu ◽  
Wuhua Yuan ◽  
Wei Xiang

In the present work, the hot deformation behavior of TB18 titanium alloy was investigated by isothermal hot compression tests with temperatures from 650 to 880°C and strain rates from 0.001 to 10 s−1. The flow curves after friction and temperature correction show that the peak stress decreased with the temperature increase and the strain rate decrease. Three typical characteristics of flow behavior indicate the dynamic softening behavior during hot deformation. At a strain rate of 0.001∼0.01 s−1, the flow stress continues to decrease as the strain rate increases after the flow stress reaches the peak stress; the flow softening mechanism is dynamic recovery and dynamic recrystallization at a lower temperature and dynamic recrystallization at a higher temperature. The discontinuous yielding phenomenon could be seen at a strain rate of 1 s−1, dynamic recrystallization took place in the β single-phase zone, and flow localization bands were observed in the α + β two-phase zone. At a higher strain rate of 10 s−1, the flow instabilities were referred to as the occurrence of flow localization by adiabatic heat. Constitutive equation considering the compensation of strain was also established, and the results show high accuracy to predict the flow stress with the correlation coefficient of 99.2% and the AARE of 6.1%, respectively.


2009 ◽  
Vol 23 (06n07) ◽  
pp. 934-939 ◽  
Author(s):  
DONG HE ◽  
JING CHUAN ZHU ◽  
YANG WANG ◽  
YONG LIU

The dynamic recrystallization (DRX) of TA 15 ( Ti -6 Al -2 Zr -1 Mo -1 V ) titanium alloy during the hot deformation process was studied by the Cellular Automata (CA) model which is base on the dislocation density theory. To build the CA model, the dislocation density model, dynamic recovery model, nucleation model and grain growth model were introduced and developed. The influences of strain rate on the microstructure evolution and flow stress character were investigated which shows that high strain rate leads to later DRX appearance, high flow stress peak value, small mean size of recrystallizing grains( R -grains) and low DRX percentage, but they have the similar Avrami curve. The characteristic of DRX process in a modeling non-uniform temperature filed (NTF) has been studied. All the simulation results show good agreement with the pioneer's work and experimental results.


1990 ◽  
Vol 21 (2) ◽  
pp. 357-375 ◽  
Author(s):  
Thomas P. Battle ◽  
Robert D. Pehlke

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