1. 1) K. Yoshihara and K. Yokoyama: JFE Giho, 15(2007), 18 (in Japanese).
2. 2) S. Fujii, M. Tanabe and Y. Yoshinari: JFE Giho, 15(2007), 23 (in Japanese).
3. 3) H. Tamaki, H. Kobayashi, M. Ago, S. Kuyama, K. Nakatsuji and K. Fukuda: Tetsu-to-Hagané, 100(2014), 485 (in Japanese).
4. 4) M. Yoshida, T. Shibagaki and Y. Onodera: Hitachi Hyoron, 71(1989), 97 (in Japanese).
5. 5) F. Tominaga, T. Shibata, A. Inayama, Y. Nasuda, N. Yamashita and Y. Sakuma: Bull. Iron Steel Inst. Jpn., 1(1996), 791 (in Japanese).