# Maximum Carbon content on the surface of Mild Steel that is Pack Carburized

Starting from a piece of Mild Steel that is then Pack Carburized, what's the maximum Carbon content that the surface can soak in? Given that we keep it around less than 1000°C and enough time, is it limited to 6.67%, the Carbon content of Cementite?

It would be helpful also if you can describe the depth of penetration of the Pack Carburization, given enough time. Something like:

Casedepth ~ $K \sqrt{time}$,

where K is the Diffusivity constant

Of course, that's wrong as I think there's a limit to the depth considering the alloy, exact temperature and dimension.