Question

For a steel alloy it has been determined that a carburizing heat treatment of 14 h duration at 809°C will raise the carbon concentration to 0.54 wt% at a point 3.6 mm from the surface. Estimate the time necessary to achieve the same concentration at a 6.0 mm position for an identical steel and at a carburizing temperature of 1100°C. Assume that D0 is 2.5 × 10-5 m2/s and Qd is 120 kJ/mol.

Answer 1

`t_2 = 27.7 hr`

Step-by-step explanation:

Given data:

carbon concentration = 0.54%

from the relation given below calculate the time required to achieve concentration at 6.00 mm from surface

`(x^2)/(Dt) = constant`

D considered constant

`(x^2)/(t) =  constant`

here, x POSITION FROM SURFACE, t is time required to achieve concentration

`(x_1^2)/(t_1) = (x_2^2)/(t_2)`

`(3.6^2)/(14) = (6^2)/(t_2)`

`t_2 = 27.7 hr`