0.15% C-steel was tested under repeated torsional stresses (n=1960r.p.m.) in air and in fresh water respectively with several mean stresses, and an endurance limit diagram has been obtained. The results obtained were as follows : 1. In fresh water the S-N curve does not become parallel to the abscissa even at 10
8 repetition of stress ; in general, the curve tends to diverge from horizontal line with the increase of mean stress, and in the case of 18kg/mm
2 of mean stress, it declines almost linearly. 2. In air the effect of mean stress to the fatigue limit is small. 3. In fresh water the effect of mean stress to the fatigue strength is considerablly large. 4. In fresh water the cracks are apt to grow in the direction normal to the principal tensile stress.
抄録全体を表示