Portevin–Le Chatelier effect under cyclic loading: experimental and numerical investigations

Abstract

The Portevin–Le Chatelier (PLC) effect is generally evidenced by the apparition of serrated yielding under monotonic tensile loading conditions. It appears at room temperature in some aluminium alloys, around in some steels and in many other metallic materials. This effect is associated with the propagation of bands of plastic deformation in tensile specimens and can in some cases lead to unexpected failures. The PLC effect has been widely simulated under monotonic conditions using finite elements and an appropriate mechanical model able to reproduce serrations and strain localization. The occurrence of serrations can be predicted using an analytical stability analysis. Recently, this serrated yielding has also been observed in specimens made of Cobalt-based superalloy under cyclic loading, after a large number of cycles. The mechanical model has been identified in this case to accurately reproduce this critical number of cycle where serrations appear. The associated apparition of localized bands of deformation in specimens and their influence on its failure has also been investigated using finite element simulations.

Keywords:

• dynamic strain ageing
• stability
• Portevin–Le Chatelier effect
• cyclic loading
• fatigue failure

Acknowledgements

Cooperation with Snecma, Turboméca and Centre d’Etudes Aéronautiques de Toulouse (CEAT) during the Program “PRC Structures Chaudes” is gratefully acknowledged, especially for the availability of the experimental data bases on the Haynes 188. The authors would also like to acknowledge J.L. Chaboche from ONERA, A. Gaubert and A. Longuet from SAFRAN, and S. Forest and F. Azzouz from Mines ParisTech for helpful discussions.

Notes

No potential conflict of interest was reported by the authors.