“…When pearlite forms in steels, austenite grain boundary is its preferential nucleation position. − The pearlite can nucleate directly from the original austenite grain boundary and become a lamellar colony by synergistic growth of two constituents (ferrite and cementite) into austenite. − In addition, the pearlite also can develop from proeutectoid phase, which means that either proeutectoid ferrite or cementite precedes pearlite and becomes pearlite. − The ferrite always acts as proeutectoid phase in hypoeutectoid steel, ,,, whereas proeutectoid cementite is dominant in eutectoid and hypereutectoid steel. ,, As an example, Mangan has observed lamellar pearlite developing from proeutectoid cementite in Fe-0.77C-0.58Mn steel. This kind of pearlite also exists in aged Fe-12Mn-0.8C high carbon high manganese steel. , Furthermore, the distinguishing feature of pearlite forming in this way is that pearlitic carbide is the same as proeutectoid carbide, no matter the carbide type or crystallographic orientation. ,, According to this feature, Mangan proposed that pearlitic carbide develops from proeutectoid carbide directly.…”