Abstract
The time-strength of steel and cast iron under repeated tension was reported previously by the authers. In the present paper the similar experiments made on the specimens with U-shaped annular notches are reported. Summary of the results is as follows:
(1) The S-N diagram of a steel for the specimens with or without notches, if both axes are shown in logarithmic scale, consists of three straight lines, i. e., a horizontal line which represents the endurance limit, another horizontal line which represents the tensile strength, and a sloped straight line, the extent of which at N=1 is equal to the true breaking strength.
(2) The S-N curves of a steel for the specimens with and without notches intersect at N=103-105, and so the time-strength of a steel for the specimens with notches at N less than the value at the intersecting point, is larger than the time-strength for without notches.
