FATIGUE STRENGTH OF AUSTENITIC STAINLESS STEEL IN VARIOUS ENVIRONMENTS: INITIATION, DENSITY AND DISTRIBUTION, AND GROWTH OF SMALL FATIGUE CRACKS.

Fatigue tests under rotating bending and reversed torsion were conducted in air, distilled water and 3 percent saltwater, using smooth specimens of austenitic stainless steel, SUS 304. Under rotating bending, the fatigue life was larger in distilled water and 3 percent saltwater than in air in the high stress region, but the fatigue strength decreased with increasing aggressiveness of test environment in the low stress region. Under reversed torsion, on the other hand, the fatigue strength was higher in an aqueous environment than in air in the whole stress region. These results were strongly related to various behaviors of small fatigue cracks such as initiation, density and growth, and were explained in terms of both cooling and corrosion effects of aqueous corrosion environment.