Quantitative evaluation of dislocations during deformation and annealing for austenitic steels using CMWP fitting method for neutron diffraction profiles

中性子回折プロファイルのCMWP解析によるオーステンナイト鋼変形と焼き戻し中の転位密度の定量評価

友田 陽*; 佐藤 成男*; Harjo, S.   ; 徐 平光   ; Gong, W.; 川崎 卓郎   

Tomota, Yo*; Sato, Shigeo*; Harjo, S.; Xu, P. G.; Gong, W.; Kawasaki, Takuro

Heterogeneous deformation behavior in a polycrystalline steel has been characterized using SEM/EBSD and neutron diffraction measurements which provide complemental insights combining microscopic details and their global averages. Type 1 (macroscopic), 2 (intergranular) and 3 (grain interior) stresses are overlapped to generate during plastic deformation accompanying substructure evolution. Upon annealing of a plastically deformed steel, the residual stresses are relived and dislocation density decreases resulting in recovery and recrystallization. To understand these phenomena quantitatively, in situ monitoring of dislocations has strongly been desired. SUS310 stainless steel was deformed in tension at room temperature followed by annealing under in situ neutron diffraction using an engineering neutron diffractometer, TAKUMI, at MLF/J-PARC. The obtained time sliced diffraction profiles were analyzed using the CMWP fitting method. As results, dislocation density was found to increase with tensile plastic deformation and decrease upon annealing. Changes in dislocation densities in individual hkl family grains were different from each other in the axial direction but nearly identical in the radial direction.