β Scribed by O.B Pedersen; A.T Winter
No coin nor oath required. For personal study only.
A study of fatigue hardening in single crystals of pure copper shows that, before saturation, stress-strain loops can display workhardening rates of about a third of the elastic shear modulus. These rates exceed tensile workhardening rates by roughly two orders of magnitude. This suggests that there is a large volume fraction of obstacles to plastic flow which are essentially non-deformable and give rise to inclvsion stresses of considerable magnitude. The much lower hardening rates in cycles after saturation when persistent slip bands have formed suggest a lower volume fraction of obstacles, as is observed by transmission electron microscopy. A simple composite model involving an inclusion stress. a bowing stress and a passing.stress accounts for the workhardening rates semi-quantitatively in terms of observed dislocation microstructures. Possible implications for polycrystals are considered.
π SIMILAR VOLUMES
The onset of strain localization in a copper single crystal, oriented for single slip, and cycled at a constant plastic strain amplitude corresponding to the low end of the plateau in the cyclic stress-strain curve, has been explored by inteferometry and analysis of hysteresis loops. Current methods
## Microcracks in Fatigued FCC Polycrystals by Interaction between Persistent Slip Bands and Grain Boundaries l'ersistent slip Lands (J'K13) are zones of liigh plastic strain localization in fatigued fcc metals. They cannot propagate across the grain boundaries of plycrystalline specimens. Consequ