Solution treated, quenched and tempered 7000 series aluminium alloy - to improve corrosion resistance and tensile strength

摘要

The thermal treatment of a thick aluminium alloy of the 7000 series contg. =0.05wt.% Cu comprises soluting, quenching and tempering. The tempering comprises (a) a pretemper at 100-150 degrees C for 5 minutes to 24 hours; (b) an intermediate temper at a higher temp., and (c) a final temper of 2-48 hours at 100-160 degrees C. The intermediate temper comprises a temp. rise at a rate =1 degrees C/minute in a temp. zone of 150-190 degrees C according to a temp. transformation of the product ( ) as a function of time (+), (+). At least one part is at a temp. higher than 190 degrees C during a total time (T) according to the function (where (T) is the duration in seconds of the step from the moment where the temperature of product reaches for the first time during temp. ascent the temp. of 190 degrees C).