Okay

so welcome to the Iron Steel Lecture.

And so the next couple of lectures

what we're going to do is we're going to look into steelmaking.

So first just a very quick rundown of the iron carbon phase diagram.

So who of you has never seen an iron carbon phase diagram?

That's good.

So as a materials engineer, you should be able to draw the iron carbon phase diagram

drunk.

And fundamentally

you should be able to understand what the parts are.

You should also remember what the temperatures are for the equilibrium phase diagram and

what the individual lines are called.

So we're going to talk about those a lot and we're going to need them to really understand

what our processes look like and what they do.

So in the end for the exam, I would expect you to know the entire iron carbon phase diagram

per heart with the exception of the peritectic part.

You don't need to know the peritectic part by heart because that's we don't only going

to need them at one point

but the rest we're going to need all the time.

The peritectic part we're only going to need during continuous casting because that's where

there's a big difference between sub peritectic

hyper peritectic and hyper peritectic steels.

But this is essentially the only time we're going to need the peritectic part.

Good.

And so the first thing we're going to do is just have a quick rundown of the iron carbon

phase diagram.

Just as a quick reminder

so iron carbon phase diagram

essentially

if we look at iron

we have three different allotrope states

which are alpha iron

gamma iron and epsilon iron.

So alpha iron is what crystal structure?

Probably all know by now.

So it was mixed.

Can I repeat?

Thank you.

Oh, it says it there.

Shouldn't have asked.

So of course

BCC

gamma iron is FCC

and these are the two phases we're going to talk about

99% of the time.

So the BCC is typically in the equilibrium phase diagram is the low temperature modification

and the FCC is the high temperature modification up to a certain temperature.

And if you go to very high temperature, then it's BCC again.

The reason for that is that we have different magnetic contributions to the crystal lattice