Effect of microcrystallites formed by deformation on the growth and orientation of grains during recrystallization of iron

Abstract

Changes of an ultradispersed structure in deformed iron after annealing have been studied. Ultradispersed structures of two different types, cellular and submicrocrystalline (SMC) ones, have been formed in iron by high pressure torsion deformation. The effect of the deformation structure type on the temperature of recrystallization onset, the size of recrystallized grains, and the recrystallization texture has been explored. A comparison of recrystallization of the initial cellular and SMC structures should be made to determine the role of microcrystallites. The recrystallization temperature of iron with an SMC structure is 200 to 250°С lower than that of iron with a cellular structure because of the presence of microcrystallites, which are ready recrystallization nuclei. The recrystallization (annealing at 750°C, 1h) of the cellular structure results in the formation of a coarse-grained structure with an average recrystallized grain size that is by an order of magnitude larger than that after the same annealing of the SMC structure (5 and 180 μm, respectively). The significantly different feature of the SMC structure in contrast to the cellular one is the annealing-assisted formation of a <110> recrystallization texture in it, whereas the annealing of iron with the cellular structure does not cause the formation of a recrystallization macrotexture. An increase in the sharpness of the recrystallization texture correlates with a decrease in the average grain-boundary misorientation angle.

An Empirical Model of Submicrocrystalline Structure Formation and Hardening upon Severe Plastic Deformation in Iron

“…In Fig. 1 we present raw data of hardness vs strain and TEM images of pure iron which is taken from our previous papers [10,11]. It can be seen (Fig.…”