The tensile properties and fatigue endurance limits of several widely used P/M steels have been tested. Statistical estimates of the 99.9% survival stress have shown that fatigue endurance ratios can vary from 0.16 to 0.47. Thus the use of 0.38 as a rule of thumb for estimating the fatigue endurance limit from static tensile property data can result in large errors.
The single most effective method of improving fatigue properties is to increase the part density.
Fractographic observations were made on some of the fatigue failures, including stable and unstable crack growth.