Observations of serration characteristics and acoustic emission during serrated flow of an Al–Mg alloy

Study of serrated flow is important for the production of metal alloy parts with smooth surfaces and for fundamental understanding of microscale plastic deformation. In this experimental investigation of a rolled Al–Mg alloy, serrated flow was observed for the entire plastic flow region at three different strain rates. Strain and strain rate dependent serration amplitudes and widths were quantified. In addition, the acoustic emission (AE) signature from the plastic flow region was analyzed in detail and was related to the serrations in the macroscopic stress versus strain results. For all experiments, deformation bands on the surfaces of the specimens were found to be consistent with ‘Type B’ serrations. Video observations of the deformation bands were synchronized with the AE, and the deformation bands were found to coincide with more persistent AE bursts and anomalies in the serrations.