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Mao, W.; Gong, W.; Harjo, S.; Morooka, Satoshi; Gao, S.*; Kawasaki, Takuro; Tsuji, Nobuhiro*
Journal of Materials Science & Technology, 176, p.69 - 82, 2024/03
The yield stress of Fe-24Ni-0.3C (wt.%) metastable austenitic steel increased 3.5 times (158 551 MPa) when the average grain size decreased from 35 m (coarse-grained [CG]) to 0.5 m (ultrafine-grained [UFG]), whereas the tensile elongation was kept large (0.87 0.82). neutron diffraction measurements of the CG and UFG Fe-24Ni-0.3C steels were performed during tensile deformation at room temperature to quantitatively elucidate the influence of grain size on the mechanical properties and deformation mechanisms. The initial stages of plastic deformation in the CG and UFG samples were dominated by dislocation slip, with deformation-induced martensitic transformation (DIMT) also occurring in the later stage of deformation. Results show that grain refinement increases the initiation stress of DIMT largely and suppresses the rate of DIMT concerning the strain, which is attributed to the following effects. (i) Grain refinement increased the stabilization of austenite and considerably delayed the initiation of DIMT in the 111//LD (LD: loading direction) austenite grains, which were the most stable grains for DIMT. As a result, most of the 111//LD austenite grains in the UFG specimens failed to transform into martensite. (ii) Grain refinement also suppressed the autocatalytic effect of the martensitic transformation. Nevertheless, the DIMT with the low transformation rate in the UFG specimen was more efficient in increasing the flow stress and more appropriate to maintain uniform deformation than that in the CG specimen during deformation. The above phenomena mutually contributed to the excellent combination of strength and ductility of the UFG metastable austenitic steel.
Yamashita, Takayuki*; Harjo, S.; Kawasaki, Takuro; Morooka, Satoshi; Gong, W.; Fujii, Hidetoshi*; Tomota, Yo*
ISIJ International, 64(2), p.192 - 201, 2024/01
Zhou, Y.*; Song, W.*; Zhang, F.*; Wu, Y.*; Lei, Z.*; Jiao, M.*; Zhang, X.*; Dong, J.*; Zhang, Y.*; Yang, M.*; et al.
Journal of Alloys and Compounds, 971, p.172635_1 - 172635_7, 2024/01
Liss, K.-D.*; Han, J.-K.*; Blankenburg, M.*; Lienert, U.*; Harjo, S.; Kawasaki, Takuro; Xu, P. G.; Yukutake, Eitaro*; Kawasaki, M.*
Journal of Materials Science, 23 Pages, 2024/00
Harjo, S.; Gong, W.; Kawasaki, Takuro
Quantum Beam Science (Internet), 7(4), p.32_1 - 32_13, 2023/12
Dannoshita, Hiroyuki*; Hasegawa, Hiroshi*; Higuchi, Sho*; Matsuda, Hiroshi*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Umezawa, Osamu*
Scripta Materialia, 236, p.115648_1 - 115648_5, 2023/11
Times Cited Count:0 Percentile:0Machiya, Shutaro*; Osamura, Kozo*; Hishinuma, Yoshimitsu*; Taniguchi, Hiroyasu*; Harjo, S.; Kawasaki, Takuro
Quantum Beam Science (Internet), 7(4), p.34_1 - 34_17, 2023/10
Mao, W.; Gao, S.*; Gong, W.; Harjo, S.; Kawasaki, Takuro; Tsuji, Nobuhiro*
Scripta Materialia, 235, p.115642_1 - 115642_6, 2023/10
Times Cited Count:0 Percentile:0In the present study, a hybrid neutron diffraction and digital image correlation measurement was performed on tensile deformation of an ultrafine grain (UFG) stainless steel exhibiting a huge Lders band deformation to evaluate the individual contribution of the austenite matrix and the deformation-induced martensite to the strain hardening during the propagation of the band. Quantitative analysis revealed that the strain hardening of the austenite matrix was insufficient to maintain a uniform deformation when the flow stress was greatly enhanced by the UFG structure. The strain hardening required for the Lders band to propagate was mostly provided by the formation of martensite and the high internal stress within it.
Harjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*
Acta Materialia, 255, p.119029_1 - 119029_12, 2023/08
Times Cited Count:1 Percentile:94.84(Materials Science, Multidisciplinary)Wang, Y.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Zhang, K.*; Zhang, Z. D.*; Li, B.*
Applied Physics Letters, 123(1), p.011903_1 - 011903_6, 2023/07
Times Cited Count:0 Percentile:59.51Gong, 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)Woo, W.*; Kim, Y. S.*; Chae, H. B.*; Lee, S. Y.*; Jeong, J. S.*; Lee, C. M.*; Won, J. W.*; Na, Y. S.*; Kawasaki, Takuro; Harjo, S.; et al.
Acta Materialia, 246, p.118699_1 - 118699_13, 2023/03
Times Cited Count:4 Percentile:97.51(Materials Science, Multidisciplinary)Nishida, Masayuki*; Harjo, S.; Kawasaki, Takuro; Yamashita, Takayuki*; Gong, W.
Quantum Beam Science (Internet), 7(1), p.8_1 - 8_15, 2023/03
Gong, W.; Kawasaki, Takuro; Zheng, R.*; Mayama, Tsuyoshi*; Sun, B.*; Aizawa, Kazuya; Harjo, S.; Tsuji, Nobuhiro*
Scripta Materialia, 225, p.115161_1 - 115161_5, 2023/03
Times Cited Count:2 Percentile:48.15(Nanoscience & Nanotechnology)Lam, T.-N.*; Chin, H.-H.*; Zhang, X.*; Feng, R.*; Wang, H.*; Chiang, C.-Y.*; Lee, S. Y.*; Kawasaki, Takuro; Harjo, S.; Liaw, P. K.*; et al.
Acta Materialia, 245, p.118585_1 - 118585_9, 2023/02
Times Cited Count:2 Percentile:73.49(Materials Science, Multidisciplinary)Harjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*; Mayama, Tsuyoshi*; Kawamura, Yoshihito*
Materials Transactions, 64(4), p.766 - 773, 2023/02
Times Cited Count:1 Percentile:87.31(Materials Science, Multidisciplinary)Tsuchida, Noriyuki*; Ueji, Rintaro*; Gong, W.; Kawasaki, Takuro; Harjo, S.
Scripta Materialia, 222, p.115002_1 - 115002_6, 2023/01
Times Cited Count:4 Percentile:67.13(Nanoscience & Nanotechnology)Kawasaki, Takuro; Takahashi, Miwako*; Kiyanagi, Ryoji; Ohara, Takashi
Acta Crystallographica Section C; Structural Chemistry (Internet), 78(12), p.743 - 748, 2022/12
Times Cited Count:0 Percentile:0.01(Chemistry, Multidisciplinary)Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.
International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12
Times Cited Count:12 Percentile:98.45(Engineering, Mechanical)Gong, W.; Zheng, R.*; Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Tsuji, Nobuhiro*
Journal of Magnesium and Alloys (Internet), 10(12), p.3418 - 3432, 2022/12
Times Cited Count:12 Percentile:93.63(Metallurgy & Metallurgical Engineering)