Accession Number:

AD0274565

Title:

EFFECTS OF CONSTITUENT PARTICLES ON THE NOTCH-SENSITIVITY AND FATIGUE-CRACK-PROPAGATION CHARACTERISTICS OF ALUMINUM-ZINC-MAGNESIUM ALLOYS

Descriptive Note:

Corporate Author:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON D C

Report Date:

1962-04-01

Pagination or Media Count:

1.0

Abstract:

Sheet specimens of two Al-Zn-Mg alloys, 7075-T6AND X7275-T6, were tested to determine the relative sensitivity to sharp notches under static loading conditions and to determine relative resistance to fatigue crack propagation. These alloys differ chiefly with respect to the number and size of constituent particles, the level being considerably lower in the X7275 alloy. Reduction in particle size and number appeared to increase somewhat the ductility of unnotched specimens without impairing the static strength, but the material with the greater constituentparticle content was more resistant to fatigue crack propagation. For both materials the sensitivity to sharp notches under static loading conditions was about the same. A discussion and interpretation of the results are given. A sufficiently large number of weakened constituent particles may have a beneficial effect on fatigue crack propagation in that they can act as crack arrestors and retard the propagation of fatigue cracks. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE