The onset of Portevin–LeChatelier instabilities in tensile testing

The critical strains for the onset or disappearance of the Portevin–LeChatelier effect are discussed based on the ‘intrinsic’ approach of the elementary strain. To obtain the parameters of dynamic strain ageing (DSA), B-type serrations are analysed considering the accommodation effect. Comparing the model relations with an experimental map of critical strains for Al–3Mg and with transient behaviour after stress relaxations, it is suggested that trapping of dislocations plays a significant role during intensive DSA.