Low cycle fatigue behaviour of beta treated zirconium: Partial irreversibility of twinning and consequences for damage

lThe aim of this study is to understand the low cycle fatigue behaviour of beta treated zirconium. It focuses especially on the contribution of twinni ng mechanisms. In situ fatigue tests performed inside a scanning electron m icroscope allow the observation of the activation of twins and their partia l reversibility, depending on the applied stress. Moreover, the acoustic si gnature (shape factor) of the different twinning systems has been character ized allowing the following of inception and evolution of twins during the fatigue tests. Finally, the consequence of such a partial irreversibility o n damage and crack localization is shown. (C) 2000 Acta Metallurgica Inc. P ublished by Elsevier Science Ltd. All rights reserved.