Accession Number : AD0856763

Title :   The Effect of Inclusion Size and Distribution on Fatigue of 2024-T4 Aluminum.

Descriptive Note : Technical rept. 1 Apr 68-31 Mar 69,


Personal Author(s) : Grosskreutz, J. C. ; Shaw, G. G. ; Benson, D. K.

Report Date : JUN 1969

Pagination or Media Count : 30

Abstract : Two experiments were performed to determine the effect of inclusion size and distribution on the fatigue strength of 2024 aluminum. Rolled, 2024 Al sheet was shown to contain about twice as many inclusions larger than 10 microns in diameter in the center plane as at the surface. Bending fatigue tests, in which a zero to maximum tensile stress was applied to one surface of a flat specimen cut from the sheet, showed that when the center plane was made the tensile surface, the fatigue life was reduced to half that obtained with the original surface under tension. An experimental 2024 alloy was made from high purity constituents so that the number of inclusions larger than 10 microns was reduced by a factor of 10 over the commercial alloy. Comparative S/N curves were generated which showed that the fatigue strength of the experimental alloy was increased by 20% in the high amplitude load range and 10% in the low amplitude range. Fatigue lives were increased by a factor of 5. One sample was observed periodically during a test and it was established that crack initiation did not occur at the inclusions as it does in the commercial alloy. (Author)


Subject Categories : Metallurgy and Metallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE