BRITTLE-FRACTURE STRESSES OF AN FE-CR ALLOY (OMICRON-PHASE) UNDER HIGH HYDROSTATIC-PRESSURE AND HIGH-TEMPERATURE

In order to clarify the effect of high hydrostatic pressure on the brittle fracture stress, three point bending tests were carried out on a Fe-Cr alloy ( sigma -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 sigma -phase and transgranular cleavage fracture occurred under both pressures. The fracture stress at atmospheric pressure rose gradually with increasing temperature to about 1000 K and increased rapidly at higher temperatures.