Grain growth upon annealing of armco iron with various ultrafine-grained structures produced by high-pressure torsion deformation

The grain growth upon heating of armco iron with a submicrocrystalline (SMC) structure produced by high-pressure torsion deformation was studied. An increase in the degree of deformation improves the uniformity of the structure and leads to its refinement. The more uniform and disperse SMC structure exhibits a higher stability with respect to the secondary recrystallization whose onset determines the temperature threshold of thermal stability. An intermediate annealing of the SMC structure at the temperature of the onset of recrystallization allows one to obtain a uniform submicron-grained structure and to completely prevent the development of secondary recrystallization upon heating up to the temperature of polymorphic transformation. The intermediate annealing of a cellular structure favors grain coarsening.