ABSTRACT
The classic metallographic observations of pearlite are based on polished and etched planar sections which reveal a lamellar mixture of ferrite and cementite. When pearlite begins with the nucleation of cementite, with the ferritic component forming on this cementite, the orientation relationship is that due to Isaichev. The isothermal experiments have been revealing in that the interlamellar spacing during forced-velocity growth matches that in regular pearlite when the comparison is made at the same speed. In some steels containing relatively large concentrations of strong carbide-forming substitutional solutes such as chromium, it is possible to generate lamellar pearlite consisting of a mixture of an alloy carbide and ferrite that grow cooperatively. When particles of proeutectoid cementite exist in austenite, cooling to a temperature where eutectoid transformation become possible can lead to divorced pearlite. In this, the pre-existing cementite particles simply grow to absorb the excess carbon partitioned at the transformation front.
