Effects of texture component, dislocation evolution and precipitation on the creep resistance of T5-treated Al-Mg-Si alloy with different Cu contents

Abstract

The creep resistance of T5-treated Al-Mg-Si alloy with different Cu content was investigated in this study. Four T5-treated alloys containing no Cu, 0.4wt%Cu 0.6 wt%Cu and 0.8wt%Cu were provided and labeled as 0Cu, 0.4Cu, 0.6Cu and 0.8Cu samples. The tensile creep experiments were carried out at 250 °C. The results showed that 0.6Cu sample had the highest creep resistance, followed by 0.8Cu, 0.4Cu and 0Cu samples. Using various characterization methods, the effects of texture component, dislocation evolution and precipitation on the creep resistance were unveiled: (1) The high (Goss + R-Goss)/Brass texture ratio in 0Cu sample failed in delaying the dislocation motions. In contrast, the low ratio in 0.6Cu sample succeeded in reaching a balance between soft and hard grain orientations and enhancing the creep resistance. (2) Dislocation tangles significantly happened in 0.6Cu sample, which inhibited the continuous movement of dislocations. (3) The suitable addition of 0.6 wt%Cu behaved the most effective strengthening on the creep resistance. But unfortunately, the loss of solution strengthening occurred in 0.8Cu sample due to the over-added Cu element accelerated the precipitation of Mg and Si elements. • Creep resistance of T5-treated Al-Mg-Si alloy with different Cu contents is revealed. • Adding 0.6 wt%Cu achieves the best creep resistance, followed by 0.8%, 0.4% and 0. • A low (Goss + R-Goss)/Brass ratio enhances the creep resistance of 0.6Cu sample. • Frequent dislocation tangles enhance the creep resistance of 0.6Cu sample. • An excessive Cu addition of 0.8 wt% induces the loss of solution strengthening.