Hot Deformation and Recrystallization Mechanisms in a Coarse-Grained, Niobium Stabilized Austenitic Stainless Steel (316Nb)
Résumé
The hot deformation behavior and associated microstructural evolution of a coarse-grained
Nb-bearing austenitic stainless steel (316Nb) has been investigated by the means of torsion tests
at high temperature [1223 K to 1423 K (950 C to 1150 C)] followed by microstructural
characterization. The starting microstructure was varied by applying prior annealing. Except for
strains below 10 pct, the resistance to viscoplastic flow is not sensitive to the starting
microstructure. On the other hand, prior annealing at higher temperatures increases the
resistance to incipient viscoplastic flow and strongly impedes dynamic and post-dynamic
recrystallization by delaying the grain boundary bulging phenomenon. It also affects the static
recrystallization behavior during further annealing. The influence of the amount of available
niobium atoms, in particular close to grain boundaries, is discussed.