This is the Instructions fort consider the question

$1-$Answer all questions clearly and concisely.

$2-$ Show all calculations and justify your reasoning with appropriate diagrams or references to class materials.

$3-($Al$-$generated responses will result in penalties$).$

$4-$Use credible resources like textbooks, journal articles.the problem below

Q$1$ A steel specimen $($composition: $0\mathrm{.}4wt\%C)$ undergoes the following heat treatment:

Heated to $900C$ and held for $1$ hour.

Quenched in water to room temperature.

Tempered at $300C$ for $2$ hours.

Draw a schematic Fe$-$C phase diagram and label the critical points relevant to this treatment.

Identify the microstructural changes at each step $($austenitization$,$ quenching, tempering$).$

Explain how these microstructural changes affect the mechanical properties of the steel $($e$.$g$.,$ hardness, toughness$).$

Use the TTT diagram to justify the microstructures formed after quenching and tempering.