Rupture fragile des matériaux ductiles

Modèle physique du comportement en corrosion sous contrainte

A physical model for brittle stress corrosion craking in ductile materials

Université de Lille I. Laboratoire de Métallurgie Physique, Villeneuve d'Ascq

Abstract

The stress corrosion cracking of ductile materials is observed to occur generally by discountinuous cleavage or by a brittle intergranular mode. Recent models have been published to explain this surprising type of failure : the film-induced cleavage model, the dissolution inducing vacancies model, the adsorption model and the enhanced surface mobility model. Nevertheless these models show conflicting mechanisms. In the present paper a new physical model is proposed for both trans and intergranular stress corrosion cracking. The effect of a localized dissolution on the dislocation behavioural the crack tip is taken into account. Experimental results are described and discussed to confirm the basic ideas of this new model. The application of this model to the stress corrosion cracking behaviour of the 316L alloy in CL^- solutions is presented.