Continuous recrystallization in austenitic stainless steel after large strain deformation

Static restoration mechanisms operating during annealing were studied in a 304 steel with strain-induced submicron grain structures. The initial microstructure with an average grain size of about 0.3 mum was developed by large strain deformation at 873 K. Early annealing leads to a full relaxation of high internal stresses associated with non-equilibrium strain-induced grain boundaries, while their boundary misorientations and the average grain size barely change. Further annealing results in a transient recrystallization followed by a normal grain growth. The average grain boundary misorientation increases up to around 45degrees in the former and becomes constant in the latter. This is associated with the change in the grain boundary misorientation distribution from a characteristic strain-induced one to a near random distribution corresponding to a fully recrystallized state. The annealing processes operating in the strain-induced fine grains take place homogeneously in the whole matrix and can be called continuous recrystallization. (C) 2002 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.