A study of the surface deformation behaviour at grain boundaries in an ultra-low-carbon steel

Tensile specimens of ultra-low-carbon ferritic steel with two different grain sizes were studied by atomic force microscopy (AFM) and electron backscatter diffraction (EBSD) after different plastic strains up to 10%. Different parameters, such as the change in surface roughness and the change in misorientation with strain, were evaluated. There was good agreement between the AFM and EBSD results. Both the surface roughness and the misorientation measurements on the surface showed a linear increase with the overall strain, an obvious consequence being that both AFM and EBSD are suitable for characterising the surface deformation behaviour. The results are discussed with respect to the difference in grain size in the samples and the implication on the strain hardening behaviour.