par Pardoen, Thomas;Massart, Thierry,Jacques
Référence European Solid Mechanics Conference - ESMC 2012(8th: July 2012: Graz, Austria), Proceedings of the 8th European Solid Mechanics Conference - ESMC 2012
Publication Publié, 2012-07-15
Abstract de conférence
Résumé : The resistance to plastic flow in metals is often dominated by the presence of interfaces which interfere with dislocation nucleation and motion. Interfaces can be static such as grain and phase boundaries or dynamic such as new boundaries resulting from a phase transformation, see Fig. 1. The interface can be hard and fully impenetrable to dislocations, or soft and partly or fully transparent. The interactions between dislocations and interfaces constitute the main mechanism controlling the strength and strain hardening capacity of many metallic systems especially in very fine microstructures with a high density of interfaces. A phenomenological strain gradient plasticity theory is used to introduce, within a continuum framework, higher order boundary conditions which empirically represent the effect of interfaces on plastic flow.The strength of the interfaces can evolve during the loading in order to enrich the description of the interface response. The behaviour of single and dual phase steels, with possible TRIP effect, accounting for the interactions with static and dynamic boundaries, has been addressed, with a focus on the size dependent strength/ductility balance. The size dependent responses of weak precipitate free zones surrounding grain boundaries and of thin metallic films are treated as examples involving more than one microstructure length.