Steel composition.. quick question (1 Viewer)

[Marina89]

Can someone quickly tell me the connection between the amount of carbon in a steel and the rate at which it corrodes.. I'm guessing it's

more carbon -> more cathodic sites -> corrodes quicker

Is that right??

 

[annabackwards]

Yes, you are correct.

In fact, my teacher said if you have pure iron it doesn't rust at all. Some examples are pure Iron meteorites and some famous buildings whose name escapes me now

More carbon makes steel stronger but also less malleable (more brittle)

 

[Marina89]

Thanks heaps for the quick reply! =)

That's what I thought, but I just read over a prac (the first one on shipwrecks) and it said that the steel corroded more than the iron. If iron contains more carbon than steel, why did the steel corrode quicker? It was in the Success One book.

 

[annabackwards]

Thanks heaps for the quick reply! =)

That's what I thought, but I just read over a prac (the first one on shipwrecks) and it said that the steel corroded more than the iron. If iron contains more carbon than steel, why did the steel corrode quicker? It was in the Success One book.

Ah i see your problem.

When they say iron, they mean pure iron (as close to pure iron as you can get).
Steel is the alloy - it is the mixture of mainly Iron with some carbon.

So as you can see, there's more carbon in steel because the iron shouldn't contain carbon at all

 

[Marina89]

Oh right right I getcha. Thanks =)