Answer:
135 hour
Explanation:
It is given that a carburizing heat treatment of 15 hour will raise the carbon concentration by 0.35 wt% at a point of 2 mm from the surface.
We have to find the time necessary to achieve the same concentration at a 6 mm position.
we know that [tex]\frac{x_1^2}{Dt}=constant[/tex] where x is distance and t is time .As the temperature is constant so D will be also constant
So [tex]\frac{x_1^2}{t}=constant[/tex]
then [tex]\frac{x_1^2}{t_1}=\frac{x_2^2}{t_2}[/tex] we have given [tex]x_1=2 mm\ ,t_1=15 hour\ ,x_2=6\ mm[/tex] and we have to find [tex]t_2[/tex] putting all these value in equation
[tex]\frac{2^2}{15}=\frac{6^2}{t_2}[/tex]
so [tex]t_2=135\ hour[/tex]
