Cyclic Plastic Strain Energy and Low-Cycle Fatigue Strength of Nickel-Chrome Steel

抄録

Low-cycle fatigue strength of nickel-chrome steel under various cyclic loading conditions, such as constant strain cycling, constant load cycling with and without mean stress, was discussed in relation to the cyclic plastic strain energy. Main results obtained were as follows : (1) The lowcycle fatigue strength depends on the maximum tensile stress σ_max as well as on the cyclic plastic strain energy ; (2) in the case of fatigue-type fracture, a unique relation-ship was found between the maximum tensile stress and the cumulative plastic strain energy to fracture, while in the case of unstable deformation-type fracture, another unique relationship existed between the unstable stress and the total plastic strain energy to the initiation of the cyclic unstable deformation. These relations are approximately shown by two straight lines in a log-log diagram. The line of unstable deformation-type failure lies considerably lower than the extrapolated part of the line of fatigue-type fracture.