Many current fatigue design criteria for structural details present allowable stress ranges for specified design lives but neglect mean and residual stresses. The paper reviews published test results and shows that residual stresses and concomitant mean stresses can have a significant influence on fatigue resistance in certain cases. The beneficial effects of compressive residual stresses due to shot peening are well-known. For example, shot peening of non-load-carrying fillet-welded carbon steel and butt-welded constructional alloy steel has increased the fatigue strengths at two million cycles by 20 to 40%. Also, the fatigue resistance of weldments can be influenced significantly by the presence of residual stresses, provided that the stress ratio is equal to or less than zero and the lives are greater than one million cycles. The fatigue strength of transverse butt welds with reinforcement intact at two million cycles has been increased by 12% and 24 to 33% for stress ratios of, respectively, 0 and -1 through thermal stress relief. Such improvement has also been .shown for longitudinal non-load-carrying fillet welds (e.g., attachments, gussets, etc.) where the increases in fatigue strength at two million cycles due to thermal stress relief for stress ratios of 0, -1, and -4 were, respectively, 15,57, and 168%.

"Evaluating the Effect of Residual Stresses on Notched Fatigue Resistance," in
*Materials, Experimentation, and Design in Fatigue - Proceedings of Fatigue '81
*, Westbury Press, Guildford, England, 1981, pp 273-295. Abstracted in
*Residual Stress Effects in Fatigue, STP 776*, American Society for Testing
and Materials, Philadelphia, Pa., 1982, p. 32.