Static and Dynamic Fracture Properties for Aluminum Alloy 7475-T651and T7351.

摘要

A broad base of mechanical property data were developed on two plates of Al 7475. One of the 1-1/2-inch thick plates was in the T7351 condition and one was in the T651 condition. The tensile properties of the T651 plate were higher than those of the T7351 plate. Nearly all of the fracture toughness tests were invalid by ASTM test standards; those that were valid indicate the material possesses good toughness. The conditional toughness values (K sub Q) for identical test conditions indicate the T7351 processing possesses the superior toughness property. The smooth and notched fatigue properties were about equal to those of other 7000-series aluminum alloys. Constant amplitude fatigue crack growth resistance was better than some older 7000-series alloys and similar to other new 7000-series alloys while the stress corrosion cracking properties in a salt water environment were excellent. Most of the tests were repeated using specimens that had been subjected to 250 F (121 C) for 1000 hours. This time-temperature exposure resulted in: (1) a slight reduction in tensile strength, (2) a slight increase in conditional toughness (K sub Q) for the T651 plate and a small decrease in K sub Q for the T7351 heat treated plate, (3) a slight reduction in fatigue properties, and (4) negligible effect on the fatigue crack growth rate and corrosion properties. (Author)