Microstructures in a carburized steel after isothermal pearlitic treatment

The influence of carbon concentration variations on pearlite formation (20 h at 600 °C) in a case-carburized steel is investigated. resultant microstructure shows three distinct regions: carburized case, transition region, and the original core. microstructural from case to core regions observed be relatively sharp. investigated region (0.9 wt.% C) contains two types pearlite: ferrite + cementite M23C6, where pearlitic aggregate with M23C6 faster kinetics. kinetics (0.3 very slow only carbide. Only around 40% austenite decomposes into which, comparison 0.9 C fraction that lower by factor two. Pearlite absent (0.16 C). this predominantly martensite pro-eutectoid ferrite, well below equilibrium fraction. Ferrite limited redistribution mainly Ni, Mn, Cr, their resulting solute drag effect austenite/ferrite interface. A thermodynamic kinetic argumentation these observations provided help data, precipitation simulations, general mixed-mode Gibbs energy balance model.