Electron backscatter diffraction on pearlite structures in steel

Electron backscatter diffraction measurements were performed on a set of pearlitic steel samples after different heat treatments. The strengths and limitations of the technique with respect to the pearlite issue are presented. Interpretation of the obtained results confirmed that more than one pearlite colony may exist inside one ferrite nodule of nearly the same crystallographic orientation. It was also found that, in most cases, a misorientation of the order of several degrees exists between pearlite colonies within one ferrite nodule. Moreover, the ferrite matrix exhibits changes of crystallographic orientation inside colonies often accompanied by a network of low angle boundaries. The mean size of the ferrite nodule in the matrix was determined by means of electron backscatter diffraction. However, determination of the mean pearlite colony size was difficult and often impossible by means of both metallographic methods and electron backscatter diffraction measurements.