A steel part whose initial carbon content is 0.10 percent by mass is to be case-hardened i...

A steel part whose initial carbon content is 0.10 percent by mass is to be case-hardened in a furnace at 1150 K by exposing it to a carburizing gas. The diffusion coefficient of carbon in steel is strongly temperature dependent, and at the furnace temperature it is given to be DAB = 7.2 × 10–12 m2/s. Also, the mass fraction of carbon at the exposed surface of the steel part is maintained at 0.011 by the carbon-rich environment in the furnace. If the hardening process is to continue until the mass fraction of carbon at a depth of 0.6 mm is raised to 0.32 percent. determine how lona the part should be held in the furnace. Answer: 4.62 n