An FCC iron carbon alloy initially containing 0.25 wt % C is exposed to an oxyge
ID: 1818866 • Letter: A
Question
An FCC iron carbon alloy initially containing 0.25 wt % C is exposed to an oxygen-rich and virtually carbon-free atmosphere at 804 degrees Celsius. Under these circumstances the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere; that is, the carbon concentration at the surface position is maintained essentially at 0 wt % C. At what position (in mm) will carbon concentration be 0.18 wt % after a 14 hr treatment? The value of D at 1325 K is 4.3 * 10^-11 m^2/s. Use the tabulation of error function.Explanation / Answer
An FCC iron-carbon alloy initially containing 0.55 wt% C is exposed to an oxygen-rich
and virtually carbon-free atmosphere at 1325K (1052 °C). Under these circumstances the
carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere;
that is, the carbon concentration at the surface position is maintained essentially at 0 wt%
C. (This process of carbon depletion is termed decarburization.) At what position will the
carbon concentration be 0.25 wt% after a 10-h treatment? The value of D at 1325 K is
4.3 11 "10! m / s 2 .