DISLOCATION-STRUCTURES IN CYCLICALLY DEFORMED STEEL AISI-316L

Dislocation structures were studied in cyclical deformed polycrystalli ne austenitic stainless steel AISI 316L using transmission electron mi croscope. Specimens were strained in plastic strain amplitude epsilon( ap) controlled tests (symmetric tension-compression) at room temperatu re to failure. Thin foils were prepared from specimens cycled with pla stic 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 iden tified. Planar dislocation arrangements at low epsilon(ap) change into vein and wall structures, and cell dislocation arrangements prevail a t high epsilon(ap). Fractions which occupy individual dislocation stru ctures were determined from observations of structures in numerous gra ins. The study of the foils with appropriate orientations allowed the constructions of three-dimensional models of dominant dislocation arra ngements.