Stresscorrosion-rack grovvth behaviour of 7475 T6 retrogressed and reaged aluminium alloy

Abstract

The results of an investigation on the effects of long retrogression times of up to 4 h at 180 and 200°C, and short times of up 10 5 min at 240, 260, and 280°C, on the yield strength, electrical conductivity, and stress-corrosion-crack growth resistance of 7475 T6 aluminium alloy are presented. One optimum retrogression time to provide T6 strength and T73 electrical conductivity was selected for each temperature investigated and was applied to double-cantilever-beam (DCB) stress-corrosion-crack growth specimens. The results show that stress-corrosioncrack growth rates in retrogressed and reaged material are comparable to those in T73 material. Moreover, the 0·2% yield strengths, obtained from specimens machined from the broken DCB specimens, are also above the T6 design-strength level.