Analysis of Portevin-Le Chatelier effect of Al-Mg alloy by electronic speckle pattern interferometry

Abstract

Displacement field in AA5052 alloy during tensile test was visualized using Electronic speckle pattern interferometry. The process of nucleation and propagation of Portevin-Le Chatelier deformation band during the plastic deformation were investigated by a dynamic observation of the images of displacement contours (fringe pattern). Various types of bands were observed depending on the applied strain rate and the total strain at which the deformation band (DB) appeared. The characteristics of nucleation and propagation of DBs were discussed being compared with the serrated curve in the load. Type A and B serration observed at the high strain rate was characterized by local strain in the DB, and it was found that the difference between type A and B arises from the increase in the local strain rate. Deformation band at low strain rate showed complicated change in response to the nucleation and propagation processes. The correlation between the band propagation and the serrated curve was discussed based on the variation in density and velocity of mobile dislocation. © The Society for Experimental Mechanics Inc. 2014.