Characterization and morphological analysis of pearlite in a eutectoid steel

Three different morphologies of pearlite have been formed isothermally at three temperatures in a eutectoid steel. The interlamellar spacings of these morphologies have been measured by scanning and transmission electron microscopy. A comparison of these experimental results and the interlamellar spacing calculations using a theoretical model previously developed has allowed some standardization to be established for the morphological characterization of pearlite, in terms of sample preparation, examination conditions, and quantitative metallography procedures. It has been found that using scanning electron microscopy, the morphological characterization of pearlite with interlamellar spacing finer than 0.085 μm could lead to unreliable results, since the strain induced during metallographic preparation of very fine pearlite destroys the lamellar morphology of pearlite. In that case, it is advisable to measure the interlamellar spacing of pearlite using transmission electron microscopy.