Uncoupling the effects of strain rate and adiabatic heating on strain induced martensitic phase transformations in a metastable austenitic steel

Vázquez-Fernández, Naiara I.; Nyyssönen, Tuomo; Isakov, Matti; Hokka, Mikko; Kuokkala, Veli‐Tapani

doi:10.1016/j.actamat.2019.06.053

Cited by 58 publications

(17 citation statements)

References 36 publications

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“…The adiabatic temperature increase can be estimated from the flow curves employing the Taylor–Quinney coefficient which reflects the ratio of plastic work transformed into heat or stored energy. However, this coefficient is inconstant during deformation and its value is dependent of not only the amount of strain, but also the loading mode, strain rate and temperature at which the strain was achieved [ 37 ]. It was found that, during high rate deformation of transformation-induced plasticity steel, the Taylor–Quinney coefficient of 0.82~1.00 is observed [ 38 ].…”

Section: Resultsmentioning

confidence: 99%

“…Overall, the actual temperature change is an extremely complicated subject during deformation, especially at high rate, and its effect on flow stress becomes overwhelmingly difficult to estimate correctly. Despite that, the numerical evaluation of the actual temperature rise is often simplified by only using the Taylor–Quinney coefficient as a constant value, which can lead to distinct overestimation of the adiabatic heating [ 37 ]. Therefore, the effect of adiabatic heating at high strain rate (10 s − 1 ) is not considered during constitutive modeling.…”

Section: Resultsmentioning

confidence: 99%

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Constitutive Descriptions and Restoration Mechanisms of a Fe-17Cr Alloy during Deformation at Temperatures of 700–1000 °C

Gao

Zhu

et al. 2021

Materials

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The deformation behavior for highly purified Fe-17Cr alloy was investigated at 700~1000 °C and 0.5~10 s−1. The microstructure evolution and corresponding mechanism during deformation were studied in-depth, using electron backscattering diffraction, transmission electron microscopy and precession electron diffraction. During deformation, dynamic recrystallization (DRX) occurred, along with extensive dynamic recovery, and the active DRX mechanism depended on deformation conditions. At higher Zener-Hollomon parameter (Z ≥ 5.93 × 1027 s−1), the development of the shear band was promoted, and then continuous DRX was induced by the formation and intersection shear band. At lower Zener-Hollomon parameter (Z ≤ 3.10 × 1025 s−1), the nucleation of the new grain was attributed to the combination of continuous DRX by uniform increase in misorientation between subgrains and discontinuous DRX by grain boundary bulging, and with increasing temperature, the effect of the former became weaker, whereas the effect of the latter became stronger. The DRX grain size increased with the temperature. For alleviating ridging, it seems advantageous to activate the continuous DRX induced by shear band through hot deformation with higher Z. In addition, the modified Johnson-Cook and Arrhenius-type models by conventional way were developed, and the modified Johnson-Cook model was developed, using the proposed way, by considering strain dependency of the material parameters. The Arrhenius-type model was also modified by using the proposed way, through distinguishing stress levels for acquiring partial parameter and through employing peak stress to determine the activation energy and considering strain dependency of only other parameters for compensating strain. According to our comparative analyses, the modified Arrhenius-type model by the proposed approach, which is suggested to model hot-deformation behavior for metals having only ferrite, could offer a more accurate prediction of flow behavior as compared to other developed models.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Constitutive Descriptions and Restoration Mechanisms of a Fe-17Cr Alloy during Deformation at Temperatures of 700–1000 °C

Gao

Zhu

et al. 2021

Materials

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“…2) If a high strain rate adiabatic test is interrupted and the specimen is reloaded in low strain rate isothermal conditions, the phase transformation proceeds readily without apparent "incubation strain", i.e., the transformation conditions are otherwise suitable during high rate deformation, but for some (yet unknown) reason the phase transformation does not proceed [5]. 3) The strain hardening and α´-phase transformation rates observed in a high rate adiabatic test cannot be replicated in a low rate test by applying external heating to mimic the macroscopic adiabatic temperature increase [13]. 4) Similarly, incremental loading at a high rate, which allows the specimen to cool down between the loadings, does not lead to the same phase transformation tendency as observed in low rate loading [7].…”

Section: Direct Strain Rate Effects On the α´-Transformationmentioning

confidence: 99%

“…The rapid and notable decrease in the strain hardening and phase transformation rates following a sudden strain rate increase could happen because the α´-transformation is suddenly inhibited in the preferential microstructural locations, which quickly heat up after the strain rate is increased. Similarly, the "mismatch" observed between the high strain rate tests and the low strain rate tests with external heating [13] might take place because the external heating cannot reproduce the nonhomogeneous heating at the microstructural level. Similar reasoning applies to the incremental tests carried out by Sunil and Kapoor [7]; loading of the material incrementally only helps to cool down the material between the increments, but within each high rate increment the loading conditions are still adiabatic and local hot spots might form in the microstructure.…”

Section: Direct Strain Rate Effects On the α´-Transformationmentioning

confidence: 99%

Some aspects of the behavior of metastable austenitic steels at high strain rates

et al. 2021

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Metastable austenite containing steels, i.e., steels capable of undergoing solid-state phase transformation from austenite to α´-martensite during plastic deformation, offer a very good combination of ductility, strength, and above all, exceptional strain hardening capability. In effect, in suitable plastic deformation conditions the relatively soft austenitic phase can transform to the harder α´-martensite, which increases the strain hardening rate of the material through various mechanisms. This special feature gives these kinds of alloys several beneficial properties, such as resistance against flow instabilities and increased capability to absorb deformation energy. For this reason, metastable austenite containing alloys have been extensively studied in the past. However, several open questions still remain, especially in the field of high rate deformation. This can be related to the great number and complexity of the related microstructural phenomena and their combined effects on the material response. The open questions affect both the metallurgy of the material and the numerical modeling of material behavior. The current contribution addresses some of these questions and their possible solutions, as well as gives an outlook on the possible future development directions.

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“…Using this approach, Va ´zquez-Ferna ´ndez et al removed the influence of heat accumulation and showed that the martensitic transformation rates decreased under increasing strain rates for a metastable austenitic stainless steel. 12 Strain rate and temperature effects have yet to be decoupled for 3GAHSS with lean alloy additions. In the work described herein, thermal-mechanical simulations were implemented to decouple the roles of temperature and strain rate in dictating the balance of dislocation slip and TRIP in a Q&P steel.…”

Section: Introductionmentioning

confidence: 99%

Decoupling the Impacts of Strain Rate and Temperature on TRIP in a Q&P Steel

Finfrock

Bhattacharya

McBride

et al. 2022

JOM

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The individual effects of strain rate and temperature on the strain hardening rate of a quenched and partitioned steel have been examined. During quasistatic tests, resistive heating was used to simulate the deformation-induced heating that occurs during high-strain-rate deformation, while the deformation-induced martensitic transformation was tracked by a combination of x-ray and electron backscatter diffraction. Unique work hardening rates under various thermal–mechanical conditions are discussed, based on the balance between the concurrent dislocation slip and transformation-induced plasticity deformation mechanisms. The diffraction and strain hardening data suggest that the imposed strain rate and temperature exhibited dissonant influences on the martensitic phase transformation. Increasing the strain rate appeared to enhance the martensitic transformation, while increasing the temperature suppressed the martensitic transformation.

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Uncoupling the effects of strain rate and adiabatic heating on strain induced martensitic phase transformations in a metastable austenitic steel

Cited by 58 publications

References 36 publications

Constitutive Descriptions and Restoration Mechanisms of a Fe-17Cr Alloy during Deformation at Temperatures of 700–1000 °C

Constitutive Descriptions and Restoration Mechanisms of a Fe-17Cr Alloy during Deformation at Temperatures of 700–1000 °C

Some aspects of the behavior of metastable austenitic steels at high strain rates

Decoupling the Impacts of Strain Rate and Temperature on TRIP in a Q&P Steel

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