Correspondence Relationship between the Maximum Tensile Stress and Cycle Number during the Initial Stage of Low-Cycle Fatigue Test

Abstract The variation of the maximum tensile stress in each cycle with cycle number during the initial stage of low-cycle fatigue test before crack initiation was investigated based on the theoretically derived relation that is valid before crack initiates. The experimental data were fitted well by the proposed semiempirical expressions with four, three, or two fitting parameters, which were applicable to a large range of cycle numbers. The semiempirical expression with just one fitting parameter was only applicable to a small range of cycle numbers when the maximum tensile stress in each cycle did not fall below 85 % of the maximum one that appeared, which can be used as a guideline for the initial stage before crack initiation at low temperatures.