Low-Cycle Fatigue of Materials for Submarine Construction

Materials for submarine construction were investigated to determine their low-cycle flexural fatigue behavior. Botl ferrous and nonferrous materials, including five steels with yield strengths of 40,000-230,000 psi, five nickel base, six aluminum base, and three copper base alloys were used in the study. Comparisons on the basis of three parameters-plastic strain range, total strain range, and nominal reversed stress-were made of the effects of mechanical notches, cycle pattern, weldments, and salt water corrosion. It is concluded that the relationship between total strain range and life is similar for all the materials investigated, and that it offers a more general and practical approach to design than plastic strain range or nominal reversed stress.