Transformation and twinning induced plasticity in an advanced high Mn austenitic steel processed by martensite reversion treatment

Dastur, P.; Zarei-Hanzaki, A.; Pishbin, M.H.; Moallemi, Mohammad; Abedi, H.R.

doi:10.1016/j.msea.2017.03.109

Cited by 23 publications

(11 citation statements)

References 34 publications

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“…The absence of pronounced anisotropy in both mechanical properties and crystallographic textures are among the advantages of strengthening by grain refinement [20]. This can be achieved by austenite reversion ('→) treatments, as reported for austenitic high-Mn TRIP steels [20,21]. In this scenario, Mn diffusion plays a key role since it exhibits very low diffusivity in austenite with a diffusion constant of D  = 5.89 x 10 -24 m 2 s -1 [22].…”

Section: Introductionmentioning

confidence: 93%

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

et al. 2019

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Austenite () reversion in a cold-rolled 17.6 wt.% Mn steel was tracked by means of dilatometry and in-situ magnetic measurements during slow continuous annealing. A splitting of the -reversion into two stages was observed to be a result of strong elemental partitioning between  and '-martensite during the low temperature stage between 390 and 575ºC. Atom probe tomography (APT) results enable the characterization of the Mn-enriched reversed- and the Mn-depleted remaining 'martensite. Because of its lower Mn content, the reversion of the remaining 'martensite into austenite takes place at a higher temperature range between 600 and 685ºC. APT results agree with partitioning predictions made by thermo-kinetic simulations of the continuous annealing process. The critical composition for nucleation was predicted by thermodynamic calculations (Thermo-Calc) and a good agreement was found with the APT data. Additional thermo-kinetic simulations were conducted to evaluate partitioning-governed -growth during isothermal annealing at 500°C and 600°C. Si partitioning to  was predicted by DICTRA and confirmed by APT. Si accumulates near the moving interface during -growth and homogenizes over time. We used the chemical composition of the remaining '-martensite from APT data to calculate its Curie temperature (T Curie) and found good agreement with magnetic measurements. These results indicate that elemental partitioning strongly influences not only -reversion but also the T Curie of this steel. The results are important to better understand the thermodynamics and kinetics of austenite reversion for a wide range of Mn containing steels and its effect on magnetic properties.

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Section: Introductionmentioning

confidence: 93%

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

et al. 2019

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“…It was found that the kinetics of martensitic phase transformation were enhanced if the metastable austenite would transform from ε-into α'-martensite [7]. Furthermore, deformation twinning may substantially interact with ε or α' martensite platelets [8], and may also significantly reduce the mean free path of dislocations movements.…”

Section: Introductionmentioning

confidence: 99%

The sequential twinning-transformation induced plasticity effects in a thermomechanically processed high Mn austenitic steel

Sabzi

Zarei-Hanzaki

Abedi

et al. 2018

Materials Science and Engineering: A

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Different initial microstructures with various bimodal grain size distributions (BGSD) were produced in a high Mn austenitic steel through applying a predetermined set of thermomechanical processing cycles. The corresponding room temperature mechanical properties and the related strain hardening behaviors were assessed using tensile testing method. The results indicated that in the microstructure with high grain size bimodality, the length and amplitude of rapid hardening region was well higher than the others. This was attributed to its higher capability to α'-martensite formation. In addition, the threshold strain to initiate martensitic transformation was shifted to the lower one in the microstructure with higher bimodal grain size distribution. The latter was related to the lower arisen back stresses in the interior regions of the coarser grains. Furthermore, different transformation paths were identified as the BGSD changed. The austenite could directly transform to α'-martensite (γ α') in the microstructure with lower BGSD; in this case the α'-martensite mainly appeared at the intersections of deformation twins. In contrast, in microstructures with higher BGSD, the nucleation occurred at the intersections of ε-martensite platelets. The co-existence of these transformation paths provided an extended transformation induced plasticity effect ending to a higher elongation to fracture in the course of deformation. In order to summarize the contribution of various strain hardening mechanisms, a deformation map was also constructed. Accordingly, the enhanced ductility/strength properties were attributed to the sequential operation of extended transformation induced plasticity and twinning induced plasticity effects.

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“…For instance, during plastic deformation of metastable austenite, this phase, depending upon its composition thereby its stacking fault energy, may decompose partially into either ɛand/or α'-martensite in the so-called TRIP (TRansformation Induced Plasticity) and/or exhibit TWIP (TWinning Induced Plasticity) effects. These are competing deformation mechanisms and would markedly increase the strain hardening rate, strength and ductility [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

The valuation of microstructural evolution in a thermo-mechanically processed transformation-twinning induced plasticity steel during strain hardening

Sabzi

Zarei-Hanzaki

Kaijalainen

et al. 2019

Materials Science and Engineering: A

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The successive evolution of martensitic transformation, twining and dislocation substructure formation in a transformation-twinning induced plasticity steel during room temperature straining was studied in the present work. This was materialized through microstructural observations and micro-texture examinations utilizing the electron backscattered diffraction method. To evaluate the strain hardening behaviour of the thermomechanically processed steel, tensile testing procedure to different strains at ambient temperature was practiced. The results indicated that the dislocation slip, mechanical twinning, and deformation induced ɛ/α'-martensite formation were involved as the deformation mechanisms. At the early stages of deformation, the dynamic formation of dislocation substructure, strain induced ɛ-martensite and twins from austenite played the main role in the observed work hardening behavior. Furthermore, the results demonstrated that the formation of α'-martensite was the dominant deformation mechanism at higher deformation levels. The corresponding texture analysis indicated to a double fibre texture formation, with a relatively stronger <111> at lower strains and a stronger <100> partial fibre parallel to tensile axis at higher strains. However, in the latter, the Cube, A and Goss Twin (GT)type textures were dominated. Decreasing of the Goss and S components were attributed to the preferential transformation of austenite to α'and ɛ-martensites, respectively. The presence of GT component even at higher strains approved the participation of deformation induced twinning as a dominant deformation mechanism up to failure.

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Transformation and twinning induced plasticity in an advanced high Mn austenitic steel processed by martensite reversion treatment

Cited by 23 publications

References 34 publications

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

The sequential twinning-transformation induced plasticity effects in a thermomechanically processed high Mn austenitic steel

The valuation of microstructural evolution in a thermo-mechanically processed transformation-twinning induced plasticity steel during strain hardening

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