X X a a b b c Characterization of dislocation evolution during work hardening of stainless steels by using XRD line-profile analysis Tomoaki KATO a, Shigeo SATO a, Yoichi SAITO b, Hidekazu TODOROKI b and Shigeru SUZUKI c a Graduate School of Science and Engineering, Ibaraki University 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan b Nippon Yakin Kogyo Co., Ltd. 4-2 Ojimatyo, Kawasaki-shi, Kawasaki-ku, Kanagawa 21-8558, Japan c Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Sendai, Miyagi 98-8577, Japan (Received 14 December 215, Revised 4 January 216, Accepted 7 January 216) Dislocation evolution of the austenitic stainless steels (NAS316L) and the duplex stainless steels (NAS329J3L) during tensile deformation was investigated by using X-ray diffraction lineprofile analysis. In particular, the heterogeneity of dislocation evolution in ferritic and austenitic phases in the duplex stainless steels was focused on for discussing the contribution to the work hardening of each phase. The work hardening of the austenitic stainless steels during tensile deformation was explained by using dislocation density estimated by the line-profile analysis. As for the duplex stainless steels, whereas an increase in dislocation density of the ferritic phase during tensile deformation was rather small, a distinct increase in the dislocation density was confirmed in the austenitic phase. Therefore, the work hardening of the duplex stainless steels can be ascribed to the heterogeneous work hardening in the austenitic phase. [Key Words] X-ray diffraction, Line-profile analysis, Stainless steel, Dislocation NAS329J3L NAS316L X a 4-12-1 316-8511 shigeo.sato.ar@vc.ibaraki.ac.jp b 4-2 21-8558 c 2-1-1 98-8577 47 Adv. X-ray. Chem. Anal., Japan 47, pp.167-172 (216) 167
X X 1. 1 X 2 X 195 3, 4 Ungár modified Williamson-Hall/Warren-Averbach 5-7 modified modified Rietveld Convolutional Multiple Whole Profile CMWP 8 CMWP X 2. 2.1 NAS316L NAS329J3L X 15 mm 3 mm.5 mm.167 s 1 Fig.1 NAS316L NAS329J3L NAS316L NAS329J3L 2 X NAS316L NAS329J3L 168 47
X True stress / MPa 12 1 8 6 4 2 2.2 X S/N Bragg-Brentano X X Cu Kα1 Kα2 X Kα2 X 111 Johansson-type Cu Kα1 NAS329J3L..1.2.3.4.5.6 NAS316L Fig.1 True stress-true strain curves of the NAS316L and NAS329J3L stainless steels. X 5N 4N 2.3 CMWP A D L g Wilkens 9 b ρ C hkl R e A S CMWP CMWP NAS329J3L X Fig.2 47 169
X Intensity / cps Intensity / cps 1 1 1 1 (a) exp. calc. 4 6 8 1 12 14 (b) 2 / deg 4 6 8 1 12 14 2 / deg Fig.2 CMWP analysis for XRD patterns of the NAS329J3L duplex stainless steels (a) before tensile test and (b) after fracture. 3. 3.1 NAS316L Fig.1 X CMWP ρ M Fig.3 M>1 M<1 4.5 1 15 m 2 M.1 M.25 Bailey-Hirsch Dislocation density / 1 15 m -2 5 4 3 2 1 (a)..1.2.3.4.5.6 Dislocation arrangement, M 1..8.6.4.2 (b)...1.2.3.4.5.6..1.2.3.4.5.6 Fig.3 Changes in (a) dislocation density, (b) M, and (c) crystallite size of the NAS316L austenitic stainless steels as a function of true strain. Crystallite size, <X> area / nm area 5 4 3 2 1 (c) 17 47
X T Taylor 3 α.25 µ 7 GPa Fig.3 Bailey-Hirsch σ Fig.1 Fig.4 NAS316L / MPa 8 6 4 2 from stress-strain curve Bailey-Hirsch..1.2.3.4.5.6 Fig.4 Work hardening of the NAS316L with tensile deformation estimated from dislocation density (open circle). Work hardening estimated from Fig.1 is also shown with broken line. 3.2 NAS329J3L NAS329J3L Fig.5 1.9 1 15 m 2.5 8. 1 15 m 2 M Dislocation density / 1 15 m -2 1 8 6 4 2 (a) Austenitic phase Ferrtic phase..5.1.15.2.25.3 Dislocation arrangement, M 2.4 2. 1.6 1.2.8.4...5.1.15.2.25.3 Fig.5 Changes in (a) dislocation density, (b) M, and (c) crystallite size of austenitic and ferritic phases for the NAS329J3L duplex stainless steels as a function of true strain. (b) Crystallite size <X> area / nm 6 4 2 (c)..5.1.15.2.25.3 47 171
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