抄録
The present writers have investigated the fatigue strength of hard drawn steel wire for combined stresses of rotary bending and static torsion and also the effect of torsional and tensile working on the fatigue strength for combined stresses.
The specimen was a 0.6% carbon steel wire having a diameter of 1.05mm. Hunter type rotary bending fatigue testing machine equipped with an apparatus applying the twisting moment to the specimen was employed.
The principal results of this investigation can be summarized as follows:
(1) For the range of low static torsional stress, the fatigue limit for combined stresses of asdrawn wire increases slightly compared with the fatigue limit under rotary bending, but as the static torsional stress increases beyond 22kg/mm2, it decreases, though its decrement is comparatively small.
(2) Through the torsional working with plastically twisted angles 0.03π/cm and 0.2π/cm, the fatigue limit for combined stresses can be made larger than that of as-drawn wire, and this increasing is remarkable for the range of higher static torsional stress.
(3) Also, through the tensile working, the fatigue limit for combined stresses becomes larger than that of as-drawn wire.
