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Journal Articles

Quantitatively evaluating respective contribution of austenite and deformation-induced martensite to flow stress, plastic strain, and strain hardening rate in tensile deformed TRIP steel

Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Harjo, S.; Park, M.-H.*; Shibata, Akinobu*; Tsuji, Nobuhiro*

Acta Materialia, 256, p.119139_1 - 119139_16, 2023/09

 Times Cited Count:0 Percentile:87.31

Transformation-induced plasticity (TRIP)-assisted steels exhibit an excellent combination of strength and ductility due to enhanced strain hardening rate associated with deformation-induced martensitic transformation (DIMT). Quantitative evaluation on the role of DIMT in strain hardening behavior of TRIP-assisted steels and alloys can provide guidance for designing advanced materials with strength and ductility synergy, which is, however, difficult since the phase composition keeps changing and both stress and plastic strain are dynamically partitioned among constituent phases during deformation. In the present study, tensile deformation with ${it in situ}$ neutron diffraction measurement was performed on an Fe-24Ni-0.3C (wt.%) TRIP-assisted austenitic steel. The analysis method based on stress partitioning and phase fractions measured by neutron diffraction was proposed, by which the tensile flow stress and the strain hardening rate of the specimen were resolved into factors associated with each phase, i.e., the austenite matrix, deformation-induced martensite, and the transformation rate of DIMT after differentiation, and then the role of each factor in the global strain hardening behavior was discussed. In addition, the plastic strain partitioning between austenite and martensite was indirectly estimated using the dislocation density measured by diffraction profile analysis, which constructed the full picture of stress and strain partitioning between austenite and martensite in the material. The results suggested that both the transformation rate and the phase stress borne by the deformation-induced martensite played important roles in the global tensile properties of the material. The proposed decomposition analysis method could be widely applied to investigating mechanical behavior of multi-phase alloys exhibiting the TRIP phenomenon.

Journal Articles

Lattice parameters of austenite and martensite during transformation for Fe-18Ni alloy investigated through ${it in situ}$ neutron diffraction

Gong, W.; Harjo, S.; Tomota, Yo*; Morooka, Satoshi; Kawasaki, Takuro; Shibata, Akinobu*; Tsuji, Nobuhiro*

Acta Materialia, 250, p.118860_1 - 118860_16, 2023/05

 Times Cited Count:0 Percentile:77.63(Materials Science, Multidisciplinary)

Journal Articles

Unexpected dynamic transformation from $$alpha$$ phase to $$beta$$ phase in zirconium alloy revealed by in-situ neutron diffraction during high temperature deformation

Guo, B.*; Mao, W.; Chong, Y.*; Shibata, Akinobu*; Harjo, S.; Gong, W.; Chen, H.*; Jonas, J. J.*; Tsuji, Nobuhiro*

Acta Materialia, 242, p.118427_1 - 118427_11, 2023/01

 Times Cited Count:2 Percentile:67.13(Materials Science, Multidisciplinary)

Journal Articles

Grain orientation dependence of deformation microstructure evolution and mechanical properties in face-centered cubic high/medium entropy alloys

Yoshida, Shuhei*; Fu, R.*; Gong, W.; Ikeuchi, Takuto*; Bai, Y.*; Feng, Z.*; Wu, G.*; Shibata, Akinobu*; Hansen, N.*; Huang, X.*; et al.

IOP Conference Series; Materials Science and Engineering, 1249, p.012027_1 - 012027_6, 2022/08

 Times Cited Count:0 Percentile:0.83

Journal Articles

Effective grain size refinement of an Fe-24Ni-0.3C metastable austenitic steel by a modified two-step cold rolling and annealing process utilizing the deformation-induced martensitic transformation and its reverse transformation

Mao, W.; Gao, S.*; Bai, Y.*; Park, M.-H.*; Shibata, Akinobu*; Tsuji, Nobuhiro*

Journal of Materials Research and Technology, 17, p.2690 - 2700, 2022/03

 Times Cited Count:7 Percentile:85.3(Materials Science, Multidisciplinary)

Metastable austenitic steels having ultrafine grained (UFG) microstructures can be fabricated by conventional cold rolling and annealing processes by utilizing the deformation-induced martensitic transformation during cold rolling and its reverse transformation to austenite upon annealing. However, such processes are not applicable when the austenite has high mechanical stability against deformation-induced martensitic transformation, since there is no sufficient amount of martensite formed during cold rolling. In the present study, a two-step cold rolling and annealing process was applied to an Fe-24Ni-0.3C metastable austenitic steel having high mechanical stability. Prior to the cold rolling, a repetitive subzero treatment and reverse annealing treatment were applied. Such a treatment dramatically decreased the mechanical stability of the austenite and greatly accelerated the formation of deformation-induced martensite during the following cold rolling processes. As a result, the grain refinement was significantly promoted, and a fully recrystallized specimen with a mean austenite grain size of 0.5 mm was successfully fabricated, which exhibited both high strength and high ductility.

Journal Articles

Effect of hydrogen on evolution of deformation microstructure in low-carbon steel with ferrite microstructure

Okada, Kazuho*; Shibata, Akinobu*; Gong, W.; Tsuji, Nobuhiro*

Acta Materialia, 225, p.117549_1 - 117549_13, 2022/02

 Times Cited Count:10 Percentile:92.51(Materials Science, Multidisciplinary)

Journal Articles

${it In situ}$ neutron diffraction study on the deformation of a TRIP-assisted multi-phase steel composed of ferrite, austenite and martensite

Lavakumar, A.*; Park, M. H.*; Gao, S.*; Shibata, Akinobu*; Okitsu, Yoshitaka*; Gong, W.; Harjo, S.; Tsuji, Nobuhiro*

IOP Conference Series; Materials Science and Engineering, 580, p.012036_1 - 012036_6, 2019/09

Journal Articles

Nature of dynamic ferrite transformation revealed by ${it in-situ}$ neutron diffraction analysis during thermomechanical processing

Shibata, Akinobu*; Takeda, Yasunari*; Park, N.*; Zhao, L.*; Harjo, S.; Kawasaki, Takuro; Gong, W.*; Tsuji, Nobuhiro*

Scripta Materialia, 165, p.44 - 49, 2019/05

 Times Cited Count:27 Percentile:85.98(Nanoscience & Nanotechnology)

Journal Articles

In situ neutron diffraction study on microstructure evolution during thermo-mechanical processing of medium manganese steel

Nakamura, Yoshihiko*; Shibata, Akinobu*; Gong, W.*; Harjo, S.; Kawasaki, Takuro; Ito, Atsushi*; Tsuji, Nobuhiro*

Proceedings of International Conference on Martensitic Transformations: Chicago, p.155 - 158, 2018/04

Oral presentation

Fokker-Planck analysis of the runaway electron generation in tokamak disruptions

Nuga, Hideo; Matsuyama, Akinobu; Shibata, Yoshihide; Yagi, Masatoshi; Kawano, Yasunori; Fukuyama, Atsushi*

no journal, , 

no abstracts in English

Oral presentation

First trial of in situ neutron diffraction experiment with thermo-mechanical simulator at J-PARC

Harjo, S.; Shibata, Akinobu*; Park, N.*; Kawasaki, Takuro; Oishi, Kiichiro*; Aizawa, Kazuya; Tsuji, Nobuhiro*

no journal, , 

Oral presentation

Dislocation monitoring during deformation and new sample environment device for engineering studies

Harjo, S.; Kawasaki, Takuro; Tomota, Yo*; Shibata, Akinobu*; Tsuji, Nobuhiro*; Aizawa, Kazuya

no journal, , 

Oral presentation

First trial of in situ neutron diffraction experiment with thermo-mechanical simulator at J-PARC

Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Shibata, Akinobu*; Tsuji, Nobuhiro*

no journal, , 

no abstracts in English

Oral presentation

Effect of ausforming on phase transformations and carbon partitioning during Q&P process

Gong, W.*; Harjo, S.; Shibata, Akinobu*; Tomota, Yo*; Shinozaki, Tomoya*; Tsuji, Nobuhiro*

no journal, , 

Oral presentation

Strain hardening behavior of metastable austenitic steel with TRIP effect; Insights from stress and strain partitioning

Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Park, M.-H.*; Shibata, Akinobu*; Tsuji, Nobuhiro*

no journal, , 

Oral presentation

Grain size effect on the strain hardening behavior of Fe-24Ni-0.3C metastable austenitic steel studied by in-situ neutron diffraction

Mao, W.; Gao, S.*; Gong, W.; Park, M. H.*; Bai, Y.*; Shibata, Akinobu*; Tsuji, Nobuhiro*

no journal, , 

Oral presentation

In situ neutron diffraction study on lattice parameter changes of austenite and martensite during transformation in Fe-18Ni alloy

Gong, W.; Harjo, S.; Tomota, Yo*; Morooka, Satoshi; Kawasaki, Takuro; Shibata, Akinobu*; Tsuji, Nobuhiro*

no journal, , 

Oral presentation

Deformation mechanism analysis of hydrogen-charged SUS310S using in situ neutron diffraction measurements

Ito, Tatsuya; Ogawa, Yuhei*; Gong, W.; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.

no journal, , 

no abstracts in English

Oral presentation

In situ neutron diffraction study on deformation behavior of hydrogen-charged SUS310S austenitic steel

Ito, Tatsuya; Ogawa, Yuhei*; Gong, W.; Mao, W.; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.

no journal, , 

no abstracts in English

19 (Records 1-19 displayed on this page)
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