Study of the fatigue strength of smooth and notched samples in relation to the manufacturing technology and test temperature

Abstract

1. Independently of the test temperature, the technological factor has a greater effect on the strength of smooth and a less substantial effect on the strength of notched samples. 2. A fall in the test temperature leads to a more substantial increase in the fatigue strength of electropolished samples, which lack work-hardened surface layers, than in that of mechanically-processed samples (which have considerable work-hardened layers), there being a tendency for the fatigue strength to increase most for sample constructions giving the lowest stress-concentration coefficient. 3. The change in stress-sensitivity coefficient q with increasing tensile strength of the material σB bears an attenuating character; the strength of materials for which the rate of increase in q diminishes sharply is approximately equal to 100 kg/mm2. 4. The results of fatigue tests on materials in a nonuniform state of stress (i. e., results derived from mechanically-processed samples) should be treated with caution.