動的フェライト変態した低合金鋼の組織観察と集合組織評価

Microstructure observation and texture evaluation of low alloy steel after dynamic ferrite transformation

徐 平光   ; 友田 陽*; Gong, W.*; Vogel, S. C.*; 鈴木 裕士  ; 鈴木 徹也*

Xu, P. G.; Tomota, Yo*; Gong, W.*; Vogel, S. C.*; Suzuki, Hiroshi; Suzuki, Tetsuya*

二相域で大ひずみ圧縮中のフェライト結晶方位密度は小ひずみ加工より著しい変化を示したが、その形成機構はまた不明瞭のため、同じプロセスで熱間圧縮した低合金鋼試料を用い、走査型電子顕微鏡と飛行時間法中性子回折装置でミクロ組織とバルク集合組織を評価した。組織観察によって、大ひずみ圧縮した試料は動的再結晶が生じたことを確認した。その集合組織は強い(001)[uvw]と(111)[uvw]繊維配向が構成され、以前の中性子その場回折実験から予想した結果と一致した。

Our neutron diffraction study of deformation induced ferrite transformation showed that at the lower temperature in the dual phase region, the evident change in grain orientation density of ferrite was found between large strain hot compression and small strain hot compression. In this study, the microstructure observation showed that the dynamic recrystallization occurred during the hot compression. The texture evaluation showed a strong (001)[uvw] component together with a (111)[uvw] fiber, which is consistent with our previous neutron analysis on grain orientation density. At 913K in the dual phase region, the large deformation resulted into coarse-fine mixed microstructure. The coarse grains were related to the untransformed austenite while the fine grains were partially related to the dynamic transformation of ferrite and partially related to the dynamic recrystallization of ferrite. It suggested that the dynamic ferrite transformation was orientation-dependent.