Constitutive relationships for hot deformation of austenite

Mirzadeh, Hamed; Cabrera, J.M.; Najafizadeh, A.

doi:10.1016/j.actamat.2011.07.008

Cited by 257 publications

(123 citation statements)

References 34 publications

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“…The stress multiplier α is an adjustable constant which brings ασ into the correct range that gives linear and parallel lines in ε ln versus )} ln{sinh(ασ plots and it can be estimated by α ≈β/n'. Since the deformation mechanism during hot working is usually based on the glide and climb of dislocations, the lattice self-diffusion activation energy can be employed as the deformation activation energy to determine Z [19]. As a result, the value of Q SD = 270 kJ/mol [8,18] was considered for both steels in this work.…”

Section: Constitutive Modelingmentioning

confidence: 99%

“…Therefore, the abovementioned comparison regarding the onset of DRX is not totally reliable. However, since the flow stress during hot deformation, resulted from the intragranular motion of dislocation, does not normally depend on grain size [19][20][21], the comparison regarding the flow stresses can be used safely. …”

Section: Characteristic Points Of Flow Curves Vs Zmentioning

confidence: 99%

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Hot deformation behavior, dynamic recrystallization, and physically-based constitutive modeling of plain carbon steels

Saadatkia

Mirzadeh

Cabrera

2015

Materials Science and Engineering: A

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144

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The high-temperature deformation behaviors of low and medium carbon steels with respectively 0.06 and 0.5 wt.% C were investigated under strain rate and temperature ranges of 10 -4 -10 -1 s -1 and of 900-1100 °C. Three types of dynamic recrystallization (DRX) flow behaviors were identified, namely single peak, multiple transient steady state, and cyclic behaviors. The normalized critical stress (and strain) for the low and medium carbon steels were about 0.846 (0.531) and 0.879 (0.537), respectively. For both steels, the apparent deformation activation energy and the power of the hyperbolic sine law were found to be near the lattice self-diffusion activation energy of austenite (270 kJ/mol) and 4.5, respectively. As a result, it was concluded that the flow stress of plain carbon steels during hot deformation is mainly controlled by dislocation climb, and based on physically-based constitutive analysis, it was found that carbon has a slight effect on the hot flow stress of plain carbon steels. The significance of the approach used in this work was shown to be its reliance on the theoretical analysis based on the deformation mechanisms, which makes the comparison more reliable.

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Section: Constitutive Modelingmentioning

confidence: 99%

Section: Characteristic Points Of Flow Curves Vs Zmentioning

confidence: 99%

Hot deformation behavior, dynamic recrystallization, and physically-based constitutive modeling of plain carbon steels

Saadatkia

Mirzadeh

Cabrera

2015

Materials Science and Engineering: A

Self Cite

144

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“…In hot deformation studies, it is common to consider the combined effects of temperature and strain-rate on a single parameter, i.e., the so-called Zener-Hollomon (Z) parameter [29]. In the high strain rate regime it is accepted that Z has an exponential dependence on stress as follows [30]:…”

Section: Constitutive Analysismentioning

confidence: 99%

Dynamic deformation response of Al-Mg and Al-Mg/B4C composite at elevated temperatures

Rezayat

Parsa

Mirzadeh

et al. 2018

Materials Science and Engineering: A

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The dynamic deformations at high temperatures of Al-3wt.%Mg alloy and Al-3wt.%Mg/B 4 C composites with different volume fractions and particle sizes were studied using a dilatometer deformation instrument and a split Hopkinson pressure bar operating at strain rates of 10 to 1000 1/s. A comprehensive analytical procedure was developed to correct the effects of adiabatic heating, friction at interface of the specimen and bars, and strain rate variation, on flow stress curves. Then based on corrected data, a physical based constitutive equation was developed for modeling and prediction of flow stress. It was observed that composites in comparison with single phase alloy, after initial straining, showed lower hardening rate which is unexpected. EBSD micrographs and finite element analysis were used to investigate microstructural evolution and deformation condition around particles. It was concluded that particle fracture during deformation which is more expectable in larger particles, and also higher adiabatic heating in composite and not recrystallization related phenomena, are the main reasons for softening of stress flow curves at large deformation.

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“…The understanding of the microstructural behavior of the steel under consideration is therefore required, together with the constitutive equations describing material flow [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

A simple constitutive model for predicting flow stress of medium carbon microalloyed steel during hot deformation

2015

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 A Simple Constitutive Model for Predicting Flow Stress of Medium Carbon Microalloyed Steel during Hot Deformation AbstractThe constitutive behavior of a medium carbon microalloyed steel during hot working over a wide range of temperatures and strain rates was studied using the Johnson-Cook (JC) model, the Hollomon equation, and their modifications. The original JC model was not able to predict the softening part of the flow curves and the subsequent modifications of the JC model to account for the softening stage and the strain dependency of constants were not satisfactory owing to the uncoupled nature of the JC approach regarding strain rate and temperature. The coupled effect of these variables was considered in the form of Zener-Hollomon parameter (Z) and the constants of the Hollomon equation were related to Z. This modification was found to be useful for the hardening stage but the overall consistency between the experimental flow curves and the calculated ones was not good. Therefore, a simple constitutive model was proposed in the current work, in which by utilization of the peak stress and strain into the Hollomon equation, good prediction abilities were attained. Conclusively, the proposed model can be considered as an efficient one for modeling and prediction of hot deformation flow curves.

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Constitutive relationships for hot deformation of austenite

Cited by 257 publications

References 34 publications

Hot deformation behavior, dynamic recrystallization, and physically-based constitutive modeling of plain carbon steels

Hot deformation behavior, dynamic recrystallization, and physically-based constitutive modeling of plain carbon steels

Dynamic deformation response of Al-Mg and Al-Mg/B4C composite at elevated temperatures

A simple constitutive model for predicting flow stress of medium carbon microalloyed steel during hot deformation

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