Age hardening potential of an Al-4.6 wt.% Mg alloy with Cu addition

Abstract

The ageing behavior of an Al-4.6Mg-0.54Cu (in wt.%) alloy was studied after: (i) solution treatment for 1h at 530°C, and (ii) annealing at 280°C for 3h. Both groups of the heat treated specimens underwent further thermo-mechanical processing: 5% pre-deformation in tension + artificial ageing at various temperatures: 140°, 160° and 180°C for 30 min. Effect of the thermomechanical processing on the microstructure and mechanical properties was investigated by tensile testing and electrical resistivity measurements. Solutionizing at 530°C resulted in higher resistivity level indicating that the most of solute atoms are retained in the solid solution. This provides great potential for precipitation hardening in a wide range of ageing temperatures. On the other hand, it appears that most of the main alloying elements precipitated during the annealing at 280°C thus diminishing the ageing potential. After further thermo-mechanical processing, the specimens annealed at 280°C showed significantly lower strength level than once solutionized at 530°C.