GATE Mechanical 2023 | Question: 42

Question

A steel sample with $1.5 \; \mathrm{wt}. \%$ carbon (no other alloying elements present) is slowly cooled from $1100^{\circ} \mathrm{C}$ to just below the eutectoid temperature $\left(723^{\circ} \mathrm{C}\right)$. A part of the iron-cementite phase diagram is shown in the figure. The ratio of the pro-eutectoid cementite content to the total cementite content in the microstructure that develops just below the eutectoid temperature is ___________.
 

(Rounded off to two decimal places)

 

Answer 1

Mass fraction of proeutectoid cementite,

m1=(1.5-0.8)/(6.7-0.8)=0.1186

Mass Fraction of Total Cementite,

m2=(1.5-0.035)/(6.7-0.035)=0.2198

(m1/m2)=0.1186/0.2198=0.54