What Does Rust Do To The Steel?

[Gondor]

I'm not a metallurgist and have no idea what rust does chemically to the steel but I know that once it appears heavily you can throw away your knife.

[wvbreamfisherman]

Well aside from the obvious (oxidation of the iron to various iron oxides, some of which are very weak mechanically and flake off), removing iron from the matrix of the steel weakens it and makes it more prone to cracking.

Surface rust is usually not a big problem unless it causes deep pits.

Remove the surface rust with steel wool or a wire brush and oil the blade to keep it from rusting further, and it will likely be fine.

[Gondor]

Yes, aside from the obvious. Some say that it messes with steel quality and that it destroys the effect of heat treatment which is, as we all know, one of the most important features of the steel.

[Theo]

Originally Posted by Gondor

Yes, aside from the obvious. Some say that it messes with steel quality and that it destroys the effect of heat treatment which is, as we all know, one of the most important features of the steel.

A lot of heat treatments are surface treatments. Damaging the surface of these types of metals will result in sub standard performance.

[Judy Ann]

I read somewhere that if you have a rusty knife you can stick the blade in an onion for a period of time and the rust will be gone. I take care of my stuff so I haven't anything to try that out with.

[ghostdog]

Good info from all the above.

Rust is a quick way to dull an edge. The steel is thin there so rust causes a lot of damage in a very short while.

[mamabear]

Like Judy Ann said, it's important to take care of your "stuff". I have been know to use a little sand paper to take the rust away if it's not too bad and then be sure the knife is well oiled afterwards.

[dinosaur]

The breamfisherman is right. Rust is iron oxide. Scrape a bunch of it off and blend it with aluminum powder, easily produced by melting down an aluminum can, and you have a great fire starter (thermite).

[Barney]

Originally Posted by dinosaur

The breamfisherman is right. Rust is iron oxide. Scrape a bunch of it off and blend it with aluminum powder, easily produced by melting down an aluminum can, and you have a great fire starter (thermite).

Excellent thinking! I have never heard let alone tried that before - live and learn. As soon as rust appears clean it with steel wool.

[Gondor]

Originally Posted by Theo

A lot of heat treatments are surface treatments. Damaging the surface of these types of metals will result in sub standard performance.

Thank you, that is the answer I've been looking for. I didn't know that such treatments include just the surface. I always wondered about that.