- 著者
-
Kaieda Yoshinari
Oguchi Atsushi
- 出版者
- 社団法人 日本金属学会
- 雑誌
- Transactions of the Japan Institute of Metals (ISSN:00214434)
- 巻号頁・発行日
- vol.22, no.2, pp.83-95, 1981
- 被引用文献数
-
4
In order to clarify the effect of high hydrostatic pressure on the brittle fracture stress, the three-point bending tests have been carried out for an Fe–Cr alloy (σ phase) containing about 47%Cr and 0.7%Si at atmospheric pressure and under 800 MPa at temperatures up to 1200 K. In the temperature range from room temperature to 1140 K, the specimens remained in the σ phase and the transgranular cleavage fracture occurred under both pressures. By scanning electron microscopy, the fracture surface was found to comprise the river pattern and the Wallner lines. The fracture stress at atmospheric pressure increased gradually with increasing temperature to about 1000 K and increased rapidly at higher temperatures. The same tendency was observed in the tests under 800 MPa but the fracture stress under 800 MPa was always higher than that at atmospheric pressure, and the difference between these stresses became larger at temperatures higher than about 1000 K. From a consideration of the stress condition around a crack, a formula σ<I><SUB>FP</SUB></I>=σ<SUB><I>F</I>0</SUB>+<I>P</I>⁄<I>K</I><SUB>σ</SUB> was proposed to represent the influence of hydrostatic pressure on the brittle fracture stress at low temperatures, where σ<SUB><I>F</I>0</SUB> and σ<I><SUB>FP</SUB></I> are the fracture stresses at atmospheric pressure and under high pressure, <I>P</I> is the pressure in positive sign and <I>K</I><SUB>σ</SUB> is the stress concentration factor at the crack. At higher temperatures, <I>K</I><SUB>σ</SUB> was replaced by Neuber’s plastic stress concentration factor <I>K</I><SUB>σ</SUB><SUP>*</SUP>.