Propagation mode of Portevin-Le Chatelier plastic instabilities in an aluminium-magnesium alloy
- Univ. de Metz (France). Lab. de Physique et Mecanique des Materiaux
The Portevin-Le Chatelier (PLC) effect is characterized by the appearance of serrations in load (hard tensile machine for constant strain rate tests) or by steps (soft tensile machine for constant stress rate tests) or by steps (soft tensile machine for constant stress rate tests) on the stress-strain curves. It is now widely accepted that the PLC propagative instability stems from the dynamic interaction between diffusing solute atoms and mobile dislocations in the temperature and strain rate ranges where dynamic strain ageing (DSA) takes place. This competition results in a negative strain-rate sensitivity. However, in some alloys, like concentrated solid solutions, shearing of precipitates accompanied by their dissolution and subsequent reprecipitation during tensile test may also lead to a negative strain rate sensitivity. In view of the renewed theoretical interest in propagative instabilities, it is important that the experimental features of band propagation be well characterized. In this work the authors present experimental results that are obtained from the investigation of the PLC bands associated with discontinuous yielding. These results show that the band strain, the band velocity and the propagation mode of the bands depend on the stress rate when the test is carried out on a soft tensile machine.
- OSTI ID:
- 409681
- Journal Information:
- Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 9 Vol. 35; ISSN 1359-6462; ISSN SCMAF7
- Country of Publication:
- United States
- Language:
- English
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