Deformation characteristics of A 6082-Al alloy at high temperatures

Abstract

High-temperature deformation of an artificially aged 6082-A1 alloy was conducted at temperatures in the range of 623-803 K at strain rates of 10 -5 to 10-2 S-1. The behavior of the alloy is characterized by high stress exponent, n and high apparent activation energy, Qa. This behavior implies the presence of threshold stress that results from dislocation interaction with second phase particles. By incorporating the threshold stress in the analysis, n was ∼7 and the true activation energy, Q1 was close to that of dislocation pipe diffusion in Al (82 kJ mol-1 ) in the temperature range of 623-723 K. At higher temperatures, n was ∼5 and Qa higher that for self diffusion in Al (∼ 200 kJ mol-1). When the experimental data were plotted using Dorn equation with an effective diffusion coefficient, D eff as normalized strain rate vs. normalized effective stress, three regions of deformation mechanisms were revealed.