Fatigue Crack Propagation Behavior in Residual Stress Fields of Laminated Inhomogeneous Metals

Abstract

Clad plates composed of low-carbon and high-carbon steels were prepared in order to investigate the effects of laminated inhomogeneity and residual stress distribution along the thickness on fatigue crack propagation behavior. The fatigue crack propagation rates of the tempered clad plate without residual stress were between those of both base metals, which showed behavior based on the law of mixture. The fatigue crack propagation rates of the quenched clad plates with residual stress were lower than those of either base metal under the same fatigue conditions. This was because the crack opening displacement, even in unhardened parts with tensile residual stress, was suppressed by the crack front curved due to the residual stress field balanced along the thickness, in which the stress intensity factor due to the residual stress was estimated to be almost zero.