Dipole heights in cyclically deformed polycrystalline AISI 316L stainless steel

The purpose of this work is to investigate the frequency distributions of edge dipole heights in polycrystalline AISI 316L stainless steel cyclically deformed in the temperature range 300-873 K. The effects of grain orientation, temperature and plastic strain rate on dislocation microstructure are discussed in terms of the dipole annihilation distance (hmin), the critical dipole height (hmax), the mean dipole height 〈h〉 and the variance σ2 of the frequency distributions of heights. The dipole annihilation distance (hmin) does not depend on plastic strain rate, it increases with increasing temperature and stacking fault energy. The increase of hmin as a function of temperature can be understood in terms of the climb of edge dislocations promoted by thermal processes (formation and diffusion of vacancies). Grain orientation does not affect the dipole annihilation distance. However, the frequency distribution of heights is clearly dependent on the grain considered. The classical relation between hmax and τμ is experimentally demonstrated in temperature range studied.