Question

Compute the volume percent of graphite, VGr, in a 3.1 wt% C cast iron, assuming that all the carbon exists as the graphite phase. Assume densities of 7.9 and 2.3 g/cm3 for ferrite and graphite, respectively.

Answer 1

Answer:

The volume percent of graphite is 9.9%

Explanation:

Given;

weight percent of graphite, C = 3.1wt%

density of ferrite, $\rho _f$ = 7.9 g/cm³

density of graphite, $\rho _g$ = 2.3 g/cm³

Determine the mass fraction;

$W_f = \frac{C_g - C_0}{C_g -C_f} \\\\W_f =\frac{100 - 3.1}{100-0}\\\\W_f = 0.969\\\\\\W_g = \frac{C_0 - C_a}{C_g -C_f} \\\\W_g =\frac{3.1-0}{100-0}\\\\W_g = 0.031$

Determine the volume fraction;

$V = \frac{W_g/ \rho_g}{W_f / \rho_f \ + \ W_g / \rho_g} *100 \%\\\\V = \frac{0.031/ 2.3}{0.969 / 7.9 \ + 0.031 / 2.3}*100\%\\\\V = 9.9\%$

Therefore, the volume percent of graphite is 9.9%