The process of carburization works via the implantation of carbon atoms in to the surface layers of a metal. As metals are made up of atoms bound tightly into a metallic crystalline lattice, the implanted carbon atoms force their way into the crystal structure. The carburization is produce for difusion of C in the Steel. I read that temperature for carburization are around 900ºC. The difusion of C depends of Fick'a law. For: bcc Fe , the difusion of C is D=220x10^-6*exp(122000/RT) fcc Fe , the difusion of C is D=20x10^-6*exp(142000/RT) Then difusion in austenitic steel (fcc Fe) is lower than ferritic steel (bcc Fe) ¿Why do it use a higher temperature (900ºC) if the diffusivity in fcc-fe is lower than in bcc-fe?