TEM studies of dislocation substructure in 316 austenitic stainless steel strained after annealing in various environments

Results of transmission electron microscopy investigations of specimens annealed in either air or vacuum at 600°C and strained to a total elongation of 0.5% at room temperature are presented. A macroscopically nonuniform spatial distribution of dislocations has been revealed. The dislocation density appears to be larger in the vicinity of the surface of the deformed specimens which indicates a higher work hardening rate near the scale–matrix interface. The dislocation density is also nonuniform along a plane parallel to the interface. In this case, however, the variations in the dislocation density seem to be random. The higher values of the flow stress determined in the vacuum-annealed specimens may be attributed to the higher strength of the oxide scale developed in such conditions of annealing (low pressure of the oxygen).