$4\mathrm{.}5$ Pre$-$laboratory Exercise

For a $1045$ steel:

a$)$ At what temperature should this steel be austenitised? See Fig. $4\mathrm{.}1.$

b$)$ What phases and$/$or microstructural constituents are present and in what mass fractions $($at a temperature just below the eutectoid temperature$)$ if this steel is:

$($i$)$ quenched, from the austenizing temperature.

$($ii$)$ slowly cooled from the austenitizing temperature.

Figure $4\mathrm{.}1$ Part of the Iron $-$ Carbon binary phase diagram showing the optimal austenitising temperature as a function of carbon content.