Study of Recrystallization in High Manganese Steels by Means of the EBSD Technique

The softening processes that take place after hot deformation in two high Mn steels, one of them microalloyed with 0.1%Nb, have been investigated. Double hit torsion tests were carried out in order to determine the mechanical softening at temperatures ranging from 900 to 1100°C. In addition, the applicability of different parameters obtained by means of the Electron Back Scattering Diffraction (EBSD) technique to estimate the recrystallized fraction was investigated. It has been found that the Grain Orientation Spread (GOS) is the parameter that best allows quantifying the recrystallized fraction under the conditions investigated. The correlation between the mechanical softening and the recrystallized fraction measured by EBSD depends on the material and deformation conditions. A good correlation between both values is observed for the base steel at all the temperatures. However, for the Nb microalloyed steel, although at high temperatures a good correlation is also observed, at low temperatures the mechanical softening fraction tends to be larger than the recrystallized fraction denoting that recovery has an important contribution.