Effect of Distributions of Low Angle Grain Boundary and Dislocation Density on Strength of Al-3mass%Mg by SPD

Abstract

Al-Mg alloys processed by Severe Plastic Deformation (SPD) have higher strength due to grain refinement by dynamic recrystallization. Generally, the relationship between grain size and strength is expressed by the Hall-Petch relationship, but the strength of Al-Mg alloys processed by SPD is higher than expected from the Hall-Petch extrapolation. This phenomenon is called ``Extra-Hardening. In this study, Al-3mass%Mg alloys processed by SPD were annealed, and the fraction of grain boundaries was measured by EBSD to determine the effect of grain boundaries on the strength. The results suggest that Extra-Hardening may be an effect of strengthening by SGB, which changes significantly with the number of passes and annealing, and constant LAGB strengthening. Strength predictions using the fraction of grain boundaries were in good agreement.