著者

佐藤 成男 黒田 あす美 佐藤 こずえ 熊谷 正芳 ステファヌス ハルヨ 友田 陽 齋藤 洋一 轟 秀和 小貫 祐介 鈴木 茂

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.104, no.4, pp.201-207, 2018 (Released:2018-03-31)

参考文献数

20

被引用文献数

10

---

To investigate the characteristics of dislocation evolution in ferritic and austenitic stainless steels under tensile deformation, neutron diffraction line-profile analysis was carried out. The austenitic steel exhibited higher work hardening than the ferritic steel. The difference in the work hardening ability between the two steels was explained with the dislocation density estimated by the line-profile analysis. The higher dislocation density of the austenitic steel would originate from its lower stacking fault energy. Dislocation arrangement parameters indicated that the strength of interaction between dislocations in the austenitic steel was stronger than that in the ferritic steel. This would mainly originate from the difference in dislocation substructures; while dislocation tangle, which can be prompted by the cross slip, was expected in the ferritic steels, highly dense dislocation walls induced by planar glide of dislocations as well as the tangle were expected in the austenitic steel. It was confirmed that the stronger interaction between dislocations in the austenitic steel resulted in the smaller strain field of dislocation. Consequently, the coefficient for the root square of dislocation density in the Bailey-Hirsh equation became smaller in the austenitic steel. X-ray diffraction line-profile analysis was also carried out for the tensile-deformed specimens. The dislocation arrangement parameter evaluated by X-ray diffraction was smaller than that evaluated by neutron diffraction. This would be caused by the difference in the relationship between the loading direction and the scattering vector. On the other hand, the dislocation density evaluated by both methods was almost identical.

著者

友田 陽 関戸 信彰 徐 平光 川崎 卓郎 ハルヨ ステファヌス 田中 雅彦 篠原 武尚 蘇 玉華 谷山 明

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.103, no.10, pp.570-578, 2017 (Released:2017-09-30)

参考文献数

31

被引用文献数

15 17

---

Various methods were employed to measure the austenite volume fraction in a 1.5Mn-1.5Si-0.2C steel. It has been confirmed that the volume fractions determined by transmission electron microscopy, scanning electron microscopy/electron back scatter diffraction, X-ray diffraction and neutron diffraction exhibit a general trend to become larger in this order, although the values obtained by X-ray and neutron diffraction are similar in the present steel because austenite is relatively stable. The austenite volume fractions determined by diffraction methods have been found to be affected by the measuring specimen direction, i.e., texture, even by applying the conventional correcting procedure. To avoid this influence, it is recommended to measure both of volume fraction and texture simultaneously using neutron diffraction. Although synchrotron X-ray shows higher angle resolution, its small incident beam size brings poor statistic reliability. The influence of texture cannot be avoided for transmission Bragg edge measurement, either, which must be overcome to realize 2D or 3D volume fraction mapping.

著者

田村 今男 友田 陽 山岡 幸男 金谷 三郎 小沢 正俊 赤尾 明

出版者

The Iron and Steel Institute of Japan

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.59, no.3, pp.454-468, 1973-03-01 (Released:2010-10-12)

参考文献数

21

被引用文献数

40 15

---

The strength and ductility of two-phase iron alloys with a ductile second phase were studied. The alloys used in this investigation were classified in three groups, that is, Fe-Cr-Ni alloys composed of austenite and ferrite, Fe-Ni-C alloys composed of austenite and martensite, and Fe-C alloys composed of ferrite and martensite; these phases had various volume fractions.The main results obtained are as follows:(1) In case of Fe-Cr-Ni alloys having different volume fractions of phases, when the same heat treatment was given, the better combination of strength and elongation was obtained in two-phase alloys than in single-phase alloys of austenite or ferrite. The main cause of this behavior was the difference in grain size. The coarsening of grains in two-phase alloys was much slower than that in single-phase alloys.(2) The effects of grain size on strength were shown by Petch type relations even in two-phase alloys as well as in single phase ones.(3) The effect of the volume fraction of phases on tensile properties with nearly the same grain size depended on the difference between the tensile properties of the second phase and the matrix. As the ratio of the 0.2% proof stress of the second phase to that of the matrix became larger than about 3, the relationb etween 0.2% proof stress and the volume fraction became to deviate from a linear relationship; this is known as the law of mixture. This may be caused by the difference of strains in the second phase and the matrix which becomes larger with an increase of the ratio.

著者

玉城 わかな 五十嵐 佑馬 藤巻 大輔 林 誠一 友田 陽 松野 泰也 長坂 徹也

出版者

The Iron and Steel Institute of Japan

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.92, no.5, pp.340-345, 2006-05-01 (Released:2009-06-19)

参考文献数

20

被引用文献数

6 6

---

1.91 milliont of steel scrap was exported from Japan to Korea in 2003, which accounted for more than 30% of the total steel scrap exported to other countries from Japan. Change in steel scrap demand in Korea in the future will make a great influence on the amount of Japan's steel scrap domestic consumption and export. In this work, quantitative data about the steel production, steel scrap demand and consumption during 1977-2003 in Korea were collected to analyze the amounts of inhouse, industrial and obsolete scrap generation, and total steel accumulation in Korea. Then, the steel scrap demand in Korea in the future was estimated. The total accumulation of steel in Korea was estimated as 380 million t in 2003 and 548 million t in 2010, respectively. The amount of obsolete scrap generation in Korea was 7.1 million t in 1996 and 9.0 million t in 2003, which was about 3.0% and 2.4% of the total steel accumulation in each year. Supposing that the amount of crude steel production, scrap consumption percentages in B.O.F and E.A.F will be stable, the obsolete scrap generation in Korea in 2010 were estimated as 13-17 million t. This significant increase in obsolete scrap generation in Korea could exceed the current amount of the scrap import. So, self-sufficiency of steel scrap could be achieved in around 2010 in Korea.

著者

片平 和俊 鈴木 秀人 岡田 昌巳 友田 陽 岩野 利彦

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.64, no.622, pp.1475-1480, 1998-06-25

被引用文献数

7 1

---

To improve the fatigue reliability for SMn 435 steel by an environmentally sound surface modification, the influence of the modification on fracture mechanism was studied experimentally. The fatigue properties of SMn 435 are found to be obviously improved by gas soft-nitriding, so that they can no longer be estimated by using a concept of "S-N Globe"which has successfully been applied to many surface-treated materials. The detailed observations have revealed that fatigue crack initiation in a gas soft-nitrided SMn 435 specimen occurs in a hardened region near surface not in a subsurface region with virgin microstructure. The crack initiation is attributable to cyclic plastic deformation in the subsurface region. Such a crack initiation mechanism is different from that previously observed in other surface treated materials, explaining the reason why the S-N Globe concept can not be applied to the present case.