The diffusivity of carbon in iron by the steadystate method

Abstract From measurements of the rate at which carbon passed through a cylindrical iron shell, the surfaces of which were maintained at different carbon contents and measurements of the carbon distribution through the cylinder wall, the diffusivity of carbon in austenite and its variation with carbon content were determined for temperatures of 1000, 851 and 802°C. The diffusivities determined by this steady-state method are in good agreement with those reported by others and determined by a non-steady-state method. It is shown that the change in the diffusivity with concentration at 1000°C is in accord with the relation D = D 0γ (1 + C d ln γ dC ) only at low carbon content.