Influence of carbon content on static recrystallization behavior of 50% cold-rolled Fe-18Mn-9Cr-2Al-xC steels

Recrystallization behavior during annealing at various temperatures was investigated for 50% cold-rolled Fe-18Mn-9Cr-2Al-xC steels with C contents varying between 0 and 0.5 wt%. Nucleation of recrystallization occurred near randomly in the carbon-free steel, whereas increasing the carbon contents promoted preferential nucleation at carbides formed along the grain boundaries through the particle stimulated nucleation mechanism. New grains in the carbon-free steel grow freely at the expense of deformed grains until the end of recrystallization during which migration of recrystallization front was blocked by the elongated delta-ferrites. For the carbon-added steels, on the other hand, (Cr,Mn)23C6 carbides and FeAl intermetallics formed during annealing and pre-existing carbides at grain boundaries pinned the recrystallization front, and thereby suppressing the growth of new grains and developing a distinct necklace structure. Recrystallization of the carbon-added steels completed only after carbides were dissolved at higher temperatures around 900 degrees C. It is noteworthy that it is not the carbon atom itself in solid solution but carbides that promotes nucleation of recrystallization and subsequently sup-pressed growth of new grains. It was also found that tensile properties of the cold-rolled steels restored nearly to those prior to cold rolling, i.e., in as-annealed state. It is concluded that recrystallization kinetics, special dis-tribution of new grains, and texture of the cold-rolled Fe-18Mn-9Cr-2Al-xC steels are significantly affected by the carbon contents. In addition, restoration of tensile properties of cold-rolled steels by recrystallization suggests that many repetitive thermomechanical processing are applicable to the steels for forming into a desire shape.

Automated summary

The recrystallization behavior of Fe-18Mn-9Cr-2Al-xC steels with varied carbon contents was investigated during annealing at different temperatures. The study found that the presence of carbides affected both nucleation and growth of new grains, with higher carbon contents inhibiting the growth of new grains. Additionally, the tensile properties of the cold-rolled steels were found to be restored after recrystallization.