The Effect of Edge Shape of Flat-Plate Specimens on the Fatigue Strength

Abstract

Experiments were made with flat plate 13 Cr stainless steel specimens for their fatigue test in the reverse plane-bending, to study the effect of their edge shapes on their fatigue strength. The specimens had been heat treated to Rockwell hardness of C 45, and their edges were formed either by machining the specimens or by punching them. Some of the machined specimens were further machined to be rounded to various sizes of radius.
The experimental result shows: (1) that the fatigue limit of machined specimens has risen about 10 per cent as the result of rounding their edges even slightly; (2) that the fatigue limit of punched specimens has remained about 26 per cent lower than that of machined specimens of right angular edges.