DISLOCATION-STRUCTURES IN CYCLICALLY DEFORMED STEEL AISI-316L

Dislocation structures were studied in cyclical deformed polycrystalline austenitic stainless steel AISI 316L using transmission electron microscope. Specimens were strained in plastic strain amplitude epsilon(ap) controlled tests (symmetric tension-compression) at room temperature to failure. Thin foils were prepared from specimens cycled with plastic strain amplitudes = 5.10(-5), 2. 10(-4), 1.10-3 and 5.10(-3). In dependence on epsilon(ap) three basic dislocation structures were identified. Planar dislocation arrangements at low epsilon(ap) change into vein and wall structures, and cell dislocation arrangements prevail at high epsilon(ap). Fractions which occupy individual dislocation structures were determined from observations of structures in numerous grains. The study of the foils with appropriate orientations allowed the constructions of three-dimensional models of dominant dislocation arrangements.