Strain-induced grain evolution in austenitic stainless steel was studied using multiple compression, with the loading direction being changed for each pass. The tests were carried out at 873K to total strains greater than 6, using a strain rate of about 0.001/s. Multiple deformation promoted the rapid formation of many mutually crossing sub-boundaries because various slip systems operated from pass to pass. A gradual increase in misorientation across dislocation sub-boundaries, with increasing strain, finally led to the evolution of very fine grains having high-angle boundaries. It was concluded that a new grain structure could result from continuous dynamic recrystallization. Such deformation-induced grains were characterized by relatively low dislocation densities, and appreciable lattice curvatures developed in their interiors. It was suggested that high elastic distortions developed in the grain interiors, and that such strain-induced grain structures were in a non-equilibrium state.

Strain-Induced Submicrocrystalline Grains Developed in Austenitic Stainless Steel under Severe Warm Deformation. A.Belyakov, T.Sakai, H.Miura, R.Kaibyshev: Philosophical Magazine Letters, 2000, 80[11], 711-8