Question

Cooling of hypoeutectoid steel post heating forms __________ ferrite.

(a) Proeutectoid

(b) Posteutectoid

(c) Hypereutectoid 2.08%

(d) Mild eutectoid

I have been asked this question during an interview.

My question comes from Transformation of Steel and Cast Iron in division Constitution of Alloys and Phase Diagrams of Engineering Material & Metallurgy

Answer 1

Right option is (a) Proeutectoid

The explanation is: 0.022-0.8% carbon steel is heated at around 875^oC and held at this temperature. This results in the formation of homogeneous austenite. Then the steel is cooled to about 775^oC, due to which pro-eutectoid ferrite will nucleate and grow at austenite grain boundaries.