On structural mechanism of continuous recrystallization in ferritic stainless steel after large strain processing

The annealing behaviour of an Fe - 22%Cr - 3%Ni ferritic stainless steel processed by bar rolling/swaging to total strain of 4.4 at an ambient temperature was studied in the temperature range of 400 similar to 700 degrees C. The annealing behaviour was characterised by the development of continuous recrystallization involving recovery processes followed by a normal grain growth. The large strain deformation caused the very fast recovery resulting in the development of almost equiaxed polygonized microstructure in place of the highly elongated deformation (sub)grains. The polygonization development was accompanied by some increase in the transverse (sub)grain size and the formation of many low-angle subboundaries. The latter ones could be composed from the dislocations, which were emitted by the strain-induced deformation (sub)boundaries. In spite of relatively large fraction of low-angle subboundaries, such polygonized microstructure was essentially stable against a discontinuous grain coarsening. Upon further annealing, therefore, the microstructure evolution was considered as a normal grain growth.