抄録
From the tests of tensile creep rupture in notched plate specimens of 0.098 per cent carbon steel at 500°C, the following conclusion can be derived.
(1) There was considerable change in stress distribution on the cross section of the notched bottom during the early stage of the creep, but after a time no remarkable redistribution was observed.
(2) The notch-strengthening effect of creep rupture strength of the material tested was examined on the basis of the nominal stress. On the basis of the equivalent steady stress, whose increase of the true stresses with progress of creep was taken into account, the difference in rupture life between the notched specimens and the smooth specimens was found smaller than that on the basis of the nominal stress. However, the behavior of notch-strengthening was still fixed.
(3) In order to determine such a notch-strengthening effect, the following stress condition was estimated. This is the case where the level of hydrostatic component of stress at near part of the notch bottom of the notched specimen is lower than that at the middle part on the cross section, and the former level is lower than that at near part of the bottom of the smooth specimen.
(4) The initial rectangular anisotropy of the material tested was examined experimentally, but neither the level of the equivalent steady stress nor multiaxiality of the stress was affected by the present anisotropy of the material.
