1 0 0 0 OA 加工軟化モデルに基づいた降伏点現象の計算機シミュレーション
- 著者
- 小野寺 龍太 森川 龍哉 上木原 竜太
- 出版者
- The Iron and Steel Institute of Japan
- 雑誌
- 鉄と鋼 (ISSN:00211575)
- 巻号頁・発行日
- vol.87, no.1, pp.63-69, 2001-01-01 (Released:2009-06-19)
- 参考文献数
- 7
- 被引用文献数
- 1 1
The yield point phenomena in low carbon steel have been explained by the Cottrell or the Johnston-Gilman theory in terms of microscopic variables such as dislocation density, dislocation velocity and the interaction energy between dislocation and solute atom. However, the lower yield stress and the amount of the Lüders strain (stretcher strain) seems not to have been predicted by the above theories. In the present work we tried to explain the phenomena quantitatively by a phenomenological (rheological) model using macroscopic variables such as work-hardening rate and the strain rate sensitivity of flow stress which we can be measured by tensile test. In the model a new internal stress was introduced which is supposed to be work (strain)-softened and age-hardened. Numerical calculation showed that the model can predict the values of the upper and lower yield stress and the amount of the Lüders strain, and the effect of strain rate on these characteristics.
1 0 0 0 OA 第一原理計算と結晶方位解析を用いたC14 Fe2W Laves相の劈開破壊挙動の評価
- 著者
- 山﨑 重人 田中 將己 森川 龍哉 渡部 康明 山下 満男 和泉 栄
- 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
- pp.TETSU-2021-069, (Released:2021-08-05)
- 参考文献数
- 46
Cleavage fracture of C14 Fe2W Laves phase was investigated using crystal orientation measurement with scanning electron microscopy and first-principles calculations. Trace analysis of the orientations of cleavage planes reveals that cleavage fracture occurred at five types of crystal planes of (0001), {1100}, {1120}, {1101} and {1122}, among which the fracture at (0001) is the most preferable. The first-principle calculations of the surface energy for fracture, Young's modulus, and Poisson's ratio showed that the minimum fracture toughness value of 1.62 MPa·m1/2 was obtained at (0001). The tendency that the values of calculated fracture toughness become larger with the higher indexed planes is almost the same as the frequency of the types of cleavage planes in the trace analysis. It is concluded that the fracture toughness of C14 Fe2W Laves phase is controlled by the surface energy for fracture and Young’s modulus.