Alloy 7075 has been thoroughly evaluated
for corrosion resistance,of atmospheric weathering, stress-corrosion cracking
and exfoliation,in all currently available tempers. These values have been used
as  a standard for comparison in the development of more recent high strength
aerospace alloys. Within the 7XXX series of alloys,resistance to general
corrosion attack, SCC and exfoliation improves  significantly in the overage
tempers (T7 type) compared with peak  strength tempers (T6).Fatigue crack growth behavior
under spectrum loading is becoming  increasingly important in the selection of
alloys for fatigue critical  aircraft structures. Various high strength aerospace
alloys are  compared for life prediction in flight hours using two types
of  fatigue spectrums a wing root application (tension dominated),  and a
horizontal tail application (tension-compression).  develop optimum strength,
toughness and other desirable charac-  teristics for proper application of alloy
7075 sheet and plate  products. Refer to MIL-H-6088, Heat Treatment of
Aluminum  Alloys for additional information.