TENSILE DEFORMATION AND FRACTURE-BEHAVIOR OF 7150-ALUMINUM-ALLOY

Aluminum alloy 7150 was deformed to failure in the 777 condition in laboratory air at ambient, elevated and cryogenic temperatures. Temperature influenced the mechanical behaviour of the alloy for both the longitudinal and transverse orientations. Strength increased with decrease in temperature with a concomitant loss in ductility. Test results indicate that the alloy response is same for both the longitudinal and transverse orientations. No change in macroscopic fracture mode was observed with direction of testing. Fracture, on a microscopic scale, was ductile and comprised of microvoid nucleation, growth and coalescence. The macroscopic fracture behaviour was a function of test temperature. The intrinsic mechanisms and micromechanisms governing the tensile fracture process are discussed in terms of concurrent and mutually competitive influences of intrinsic microstructural features, matrix deformation characteristics, test temperature and grain-boundary failure.