Investigations on the Portevin Le Chatelier critical strain in an aluminum alloy

The critical condition for the occurrence of serrations during Portevin–Le Chatelier (PLC) effect is investigated in this work. Some experimental tensile results on an Al–Mg aluminum alloy (AA5754) are recalled. The mechanical model for strain ageing proposed by MacCormick (1989) [1] to simulate the PLC effect is described, and the critical condition usually associated to this model is discussed. This condition is shown to fail at predicting the occurrence of PLC bands in finite element (FE) simulations based on this model. An alternative loss of stability condition is proposed, which is in accordance with simulation results. This condition is used for the identification of strain ageing model parameter for Al–Mg alloy.

Critical condition for serration occurrence during PLC FE simulations. Method of identification accounting for critical plastic strain. Validation on an Al–Mg Alloy.