Effect of electrical pulse treatment on the retrogression and re-aging behavior of 6061 aluminum alloy

Effect of electrical pulse treatment (EPT) on the retrogression and re-aging behavior of Al-Mg-Si based 6061 aluminum alloy was investigated by tensile tests, hardness measurement, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The experimental results show that the electrical pulse treatment to the naturally aged 6061 alloy can simultaneously induce the material strength decrease and Portevin–Le Chatelier (PLC) reappearance during tensile test. Especially, an electrical pulse with higher current density can produce stronger retrogression effect. TEM results can't show obvious difference between naturally aged, electrical pulse treated, and as quenched 6061 alloy, but DSC test results can show obvious difference. The mechanism of precipitate evolution is discussed in sight of the dissolution of Mg-Si co-clusters inside during EPT process. TEM results also show that the re-aging behavior of pulses treated naturally aged 6061 alloy is caused by precipitation of needle-like precipitates during re-aging.