INFLUENCE OF DEFORMATION ON THE HYDROGEN BEHAVIOR IN IRON AND NICKEL-BASE ALLOYS - A REVIEW OF EXPERIMENTAL-DATA

Most of the hydrogen-induced crack propagation mechanisms occuring in metals and alloys involve various interactions of hydrogen with deform ation processes in materials. Modeling the kinetics of hydrogen entry with respect to its local concentration to assess a crack propagation rate first requires a detailed characterization of these interactions. The pu pose of this paper is to review some data illustrating the inf luence oi deformation on the hydrogen behavior in iron and nickel base alloys. Experimental data on hydrogen, deuterium and tritium diffusio n and trapping show: (a) a strain dependence of the hydrogen ingress i n b.c.c. alloys through natural or passive films; (b) a strain induced hydrogen trapping; (c) all accelerated transport of hydrogen in pre-s trained samples or during dynamic straining; (d) a hydrogen enhanced l ocalized plasticity I and (e) a deformation enhanced embrittlement. Th ese effects are shown to depend on various parameters including the hy drogen activity, the material chemistry and microstructure, the strain rate and the temperature. (C) 1998 Elsevier Science S.A.