Results of transmission electron microscopy investigations of specimens annealed in either air or vacuum at 600 o 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).