Abstract
Free cutting mild steel (EN 202) was pack carburised to give carbon contents of 0.4, 0.6 and 1.1%. The isothermal transformation curves of these steels were determined by dilatometry and confirmed by microscopy. Microhardness surveys were carried out on pro-euteetoid ferrite as It formed. From the results of these experiments it was concluded that ferrite Initially had a carbon content greater than that predicted by the equilibrium diagram. This carbon content was not uniform and increased as the carbon content of the steel increased. The morphology of pearlite changes as transformation conditions and carbon content of the steel are altered. When the steel has a high carbon content and is transformed at temperatures near the eutectoid temperature the pearlite is lamellar but low carbon steels transformed at lower temperatures in the pearlite range have a spheroidal form of pearlite.