THE ROLE OF CYCLIC SLIP LOCALIZATION IN FATIGUE DAMAGE OF MATERIALS

Cyclic slip localization is demonstrated in several classes of materials as copper single crystals, polycrystals and in a duplex austenitic-ferritic stainless steel, in measuring the cyclic stress-strain response, studying the surface relief evolution and the internal dislocation structures. The characteristic structure of the persistent slip bands accommodating high local plastic strain amplitude is correlated with the extrusion/intrusion formation on the surface, which results in fatigue crack nucleation, short crack growth, dominant crack formation, its growth and fracture. These stages represent the physical manifestation of the fatigue damage.