Abstract
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, SUS304. The initiation, density and distribution, and growth behaviour of small fatigue cracks were examined based on the detailed observations, and the effect of aqueous environment on fatigue strength was evaluated.
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 behaviours of small fatigue cracks such as initiation, density and growth, and were explained in terms of both cooling and corrosion effects of aqueous corrosive environment.
