Accession Number : AD0681026

Title :   FATIGUE CRACK PROPAGATION IN A HIGH-STRENGTH STEEL UNDER CONSTANT CYCLIC LOAD WITH VARIABLE MEAN LOADS.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Crooker,T. W. ; Lange,E. A.

Report Date : 29 NOV 1968

Pagination or Media Count : 22

Abstract : Fatigue crack propagation studies were conducted on a 9Ni-4Co-0.25C high-strength steel using a constant cyclic load and variable mean loads. The load ratio, R, was varied from +0.5 to -1.0. Fatigue crack growth rates were analyzed using the crack tip stress-intensity factor, K. The results show that mean loads exert a strong secondary influence on fatigue crack propagation. Data were fitted to two crack propagation equations which seek to account for mean loads. Both equations significantly reduced, but did not eliminate, the 'layered' scatter caused by mean loads. (Author)

Descriptors :   (*STEEL, CRACK PROPAGATION), NICKEL ALLOYS, COBALT ALLOYS, FATIGUE(MECHANICS), LOADS(FORCES)

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE