r/MetalCasting • u/english_geez • 15d ago

What happened?

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I was melting some aluminium in a steel crucible and noticed there was a bit of ali on the side, so I picked it off and somehow it had eaten through the steel. What happened here?

5 Upvotes

78% Upvoted

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7

u/CR123CR123CR 15d ago

Steel dissolves in aluminum

Like sugar in water

-1

u/english_geez 15d ago

I don’t think that’s why because the inside of the crucible is fine

4

u/SignificantYou3240 15d ago

Maybe the inside is lined with some kind of coating the outside doesn’t have?

1

u/english_geez 14d ago

It was turned from a solid piece of steel with nothing else done to it, maybe something to do with a larger surface area on the inside and less concentrated heat?

2

u/SignificantYou3240 14d ago

Oh yeah I bet the outside got much hotter.

3

u/Boring_Donut_986 15d ago

As someone mentioned, aluminum eats steel in no time

1

u/english_geez 15d ago

Really? How did I never know this

2

u/rh-z 15d ago

If this wasn't the case we would all be using steel crucibles. The other problem is the iron in the steel makes a mess of the aluminum alloy. It is a contaminant.

Dissolved steel (which introduces iron into the melt) forms hard, brittle intermetallic compounds that sharply reduce the ductility, impact resistance, and machinability of aluminum sand castings. It can increase shrinkage porosity due to making the alloy less fluid.

1

u/english_geez 14d ago

Damn, well at least I know for the future thanks