Equal-channel angular pressing and annealing of a twinning-induced plasticity steel: Microstructure, texture, and mechanical properties

Haase, Christian; Kremer, Oliver; Hu, W.; Ingendahl, Tobias; Lapovok, Rimma; Molodov, Dmitri A.

doi:10.1016/j.actamat.2016.01.056

Cited by 82 publications

(63 citation statements)

References 87 publications

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“…Bagherpour et al (Ref 17) conducted ECAP at room temperature for TWIP steels in an ECAP die of U = 120°observing a large number of cracks and concluded that flow localization was in the basis of the onset of fracture. The attempts to process TWIP steel in ECAP dies with U = 90°at room temperature have failed due mainly to fractures in the punch, and it has only been possible when the temperature has been increased to 300°C (Ref 18,19). By this process, good results have been obtained but high temperature could lead to either dynamic or static recrystallization and therefore grain size refinement is limited.…”

Section: Introductionmentioning

confidence: 93%

“…In addition, the EBSD studies have shown that this material has a slightly larger fraction of mechanical twins and the TEM studies allow to see a larger presence of secondary twinning, even with nano-twins inside the primary twins (Ref 18). Unlike ECAP at 300°C, in which some dynamic recovery are expected during severe plastic deformation (Ref 18,19,35), the room temperature microstructure has less possibilities to dislocation motion and creation of subgrains that help to accommodate the deformation. Accordingly, the number and density of defects is higher and the structure has very limited ability to enable dislocation motion or to create new deformation twins, which finally results in a very limited period of strain hardening (0.05).…”

Section: Mechanical Behaviormentioning

confidence: 99%

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Twin-Induced Plasticity of an ECAP-Processed TWIP Steel

Wang

Benito

Calvo

et al. 2016

J. of Materi Eng and Perform

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The TWIP steels show high strain hardening rates with high ductility which results in high ultimate tensile strength. This makes their processing by equal channel angular pressing very difficult. Up to now, this has only been achieved at warm temperatures (above 200°C). In this paper, a FeMnCAl TWIP steel has been processed at room temperature and the resulted microstructure and mechanical properties were investigated. For comparison, the material has also been processed at 300°C. The TWIP steel processed at room temperature shows a large increase in yield strength (from 590 in the annealed condition to 1295 MPa) and the ultimate tensile strength (1440 MPa) as a consequence of a sharp decrease in grain size and the presence within the grains of a high density of mechanical twins and subgrains. This dense microstructure results also in a loss of strain hardening and a reduction in ductility. The material processed at 300°C is more able to accommodate deformation and has lower reduction in grain size although there is a significant presence of mechanical twins and subgrains produced by dislocation activity. This material reaches an ultimate tensile strength of 1400 MPa with better ductility than the room temperature material.

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Section: Introductionmentioning

confidence: 93%

Section: Mechanical Behaviormentioning

confidence: 99%

Twin-Induced Plasticity of an ECAP-Processed TWIP Steel

Wang

Benito

Calvo

et al. 2016

J. of Materi Eng and Perform

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“…So far, only a few researches have focused on SPD of high-Mn TWIP steels [13][14][15][16][17]. Matoso [13] and Abramova [14] conducted high-pressure torsion (HPT) on different TWIP steels separately and both found significant improvements on hardness.…”

Section: Introductionmentioning

confidence: 99%

“…Grain refinement is considered a suitable way to strengthen the material, i.e. increase the yield strength, without changing the chemical composition and, therefore, maintaining the SFE value within the appropriate range [9][10][11][12][13][14][15][16][17][18]. In addition, other methods to increase the yield strength of TWIP steels have been investigated: pre-deformation [19,20], recovery annealing [21,22,23] as well as the careful control of the hot and cold rolling schedules, which is the typical production route.…”

Section: Introductionmentioning

confidence: 99%

“…Timokhina [16] has performed ECAP on a FeMnC TWIP steel at different temperatures, and described characteristics of the microstructure related to the morphology of twins and dislocations. Haase et al [17] conducted four passes of ECAP on a FeMnCAl TWIP steel, and showed the refinement of the microstructure and related it to the corresponding texture evolution and to the enhancement of the tensile strength with limited ductility. In addition, they also evaluated the effect of annealing on such properties.…”

Section: Introductionmentioning

confidence: 99%

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Equal channel angular pressing of a TWIP steel: microstructure and mechanical response

et al. 2017

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A Fe-20.1Mn-1.23Si-1.72Al-0.5C TWIP steel with ultra-fine grain structure was successfully processed through Equal Channel Angular Pressing (ECAP) at warm temperature up to four passes following the BC route. The microstructure evolution was characterized by Electron Back Scattered Diffraction (EBSD) to obtain the grain maps, which revealed an obvious reduction of grain size, as well as a decrease of the twin fraction, with increasing number of ECAP passes. The texture evolution during ECAP was analyzed by Orientation Distribution Function (ODF). The results show that the annealed material presents Brass (B) as dominant component. After ECAP, the one pass sample presents A1 * and A2 * as the strongest components, while the two passes and four passes samples change gradually towardcomponents. TEM analysis shows that all samples present twins. The twin thickness is reduced with increasing the number of ECAP passes. Nano-twins, as a result of secondary twinning, are also observed in the one and two passes samples. In the four passes sample the microstructure is extensively refined by the joint action of ultra-fine subgrains, grains and twins. The mechanical behavior was studied by tensile samples and it was found that the yield strength and the ultimate tensile strength are significantly enhanced at increasing number of ECAP passes. Although the ductility and strain hardening capability are reduced with ECAP process, the present TWIP steel shows significant uniform deformation periods with positive work-hardening rates.

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Substructure Development and Deformation Twinning Stimulation through Regulating the Processing Path during Multi‐Axial Forging of Twinning Induced Plasticity Steel

et al. 2018

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Multi-axial forging (MAF) at room temperature is employed to investigate the effects of deformation processing path and the amount of imposed strain on the deformation mechanisms of a twinning-induced plasticity (TWIP) steel.The results indicate that the twin frequency is decreased by applying the 2nd compression ( P ɛ ¼ 0.8), however, an unexpected increase is realized at the end of first MAF pass ( P ɛ ¼ 1.2). This is attributed to the change in strain path and orientation dependence of deformation twinning. The latter is phenomenal considering the previous researches reporting the suppression of twinning at the early stage of deformation (ɛ < 0.4). The same sequence is followed during the second pass of MAF process. Interestingly, the progressive and continues substructure development along with dynamic Hall-Petch effect results from deformation twinning leads to an appreciable grain refinement. The latter is accompanied by the sharp drop of hardening rate in corresponding flow curves. The microtexture analysis indicates the strengthened texture of the 1 pass-processed specimens which is weaken at the end of 2 pass due to the recrystallization and increasing the number of texture component. The current work also explores the room temperature mechanical properties of the multi axial forged workpiece through elaborating the miniaturized tensile testing method.

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Equal-channel angular pressing and annealing of a twinning-induced plasticity steel: Microstructure, texture, and mechanical properties

Cited by 82 publications

References 87 publications

Twin-Induced Plasticity of an ECAP-Processed TWIP Steel

Twin-Induced Plasticity of an ECAP-Processed TWIP Steel

Equal channel angular pressing of a TWIP steel: microstructure and mechanical response

Substructure Development and Deformation Twinning Stimulation through Regulating the Processing Path during Multi‐Axial Forging of Twinning Induced Plasticity Steel

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