Continuous dynamic recrystallization in low density steel

The high temperature deformation behavior of a duplex low density steel (Fe-17.5Mn-8.3Al-0.74C-0.14Si, wt. %) was investigated. This was performed through utilizing the hot tensile deformation scheme with a particular emphasis on the austenite grain refinement mechanisms. The extended dynamic recovery under the lowest applied strain rate (0.0001 s(-1)) was considered as the main restoration mechanism. In the latter, the misorientation was largely positioned below 15 degrees and this was attributed to the progressive formation of subgrain boundaries. Therefore, a positive effect on the material ductility behavior was provided through stress relieving phenomena. The occurrence of partial recrystallization was also traced in the microstructure during tensile deformation in the low strain rate regime. Increasing the applied strain rate to 0.1 s(-1) provided an appropriate condition for the occurrence of continuous dynamic recrystallization, where the number of subgrain boundaries was decreased and the continuous transformation of subgrains into the recrystallized grain was occurred. The recrystallized grains generally acquired a different microtexture with respect to the parent austenite grains. It was found that the presence of fine grains associated with continuous recrystallization could favour the grain boundary sliding thereby resulting in wedge-type cracking which would deteriorate the ductility behavior of the material. (C) 2016 Elsevier Ltd. All rights reserved.