RESEARCH ON THE MECHANISMS OF FATIGUE.
Rept. for 1 Dec 61-31 Aug 63,
MIDWEST RESEARCH INST KANSAS CITY MO
Pagination or Media Count:
The accumulation of fatigue damage was studied on a microscopic scale in polycrystalline aluminum cycled at constant strain. At moderate strain amplitudes, the dominant feature is a subgrain structure which originates with the clustering of dislocations into sub-boundaries during the first few hundred cycles of strain. At low strains, large concentrations of dislocation loops are formed, either near subgrain boundaries, or on glide planes in areas devoid of subgrains. These observations were used to construct a model of fatigue hardening which agrees with the published hardening curves for aluminum. Author