Deformation Twinning Behavior of Twinning-induced Plasticity Steels with Different Carbon Concentrations - Part 1: Atomic Force Microscopy and Electron Backscatter Diffraction Measurements

The deformation twinning behavior in Fe-17Mn-0.6C, Fe-17Mn-0.8C, and Fe-18Mn-1.2C (wt.%) twinning-induced plasticity (TWIP) steels was investigated by atomic force microscopy (AFM) and electron backscatter diffraction pattern (EBSD) analyses. AFM-based surface relief analysis combined with EBSD measurements was employed to determine the active twinning direction and deformation twin fraction for specific crystallographic orientations. The addition of carbon is known to increase the stacking fault energy. The < 111 > tensile orientation grains revealed suppression of deformation twinning with increasing carbon concentration; however, the deformation twin fraction in the < 144 > tensile orientation did not change as a function of the carbon concentration. These results imply that another factor in addition to stacking-fault-energy-based criteria is required to interpret the deformation twinning behavior of carbon-added TWIP steels.