Deformation Twinning Behavior of Twinning-Induced Plasticity Steels with Different Carbon Concentrations

–Part 1: Analyses by Atomic Force Microscopy and Electron Backscatter Diffraction Measurements–

Abstract

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. The AFM-based surface relief analysis combined with the EBSD measurements was employed to determine active twinning direction as well as deformation twin fraction in specific crystallographic orientations. A carbon addition is known to increase the stacking fault energy; however the deformation twin fraction in the <144> tensile orientation did not change against carbon concentration. On one hand, the <111> tensile orientation grains showed suppression of deformation twinning with increasing carbon concentration. These results imply that another factor in addition to the stacking fault energy-based criteria is required to interpret the deformation twinning behavior of carbon-added TWIP steels.