Abstract: A method and system for designing a part with improved fatigue life and resistance to stress corrosion cracking in which residual stresses existing in the part are accounted for. The performance criteria and operating conditions of the part are assessed and a total stress state is determined from the sum of the residual stresses and applied stresses acting on the part. Unified Fatigue Performance Model or Smith-Topper-Neuber parameters are used to determine fatigue life functions which, in turn, are used in conjunction with a fatigue design diagram to determine the appropriate residual stress to introduce in order to optimize the part's resistance to stress induced failure mechanisms. A residual stress distribution is then designed to avoid distortion of the part while still imparting the beneficial effects of compressive residual stress.