[RustAnodized]

Hi, I have almost no experience with chemistry and I'm sorry if this doesn't fall under the Analytical Chemistry category. If it doesn't please point me in the right direction and I will post there.

This isn't for homework and I'm not a chemistry student. Just need this question answered for a real world application.

Say you had a stainless steel pot filled with water and an anodized aluminum pot filled with water. You then took 2 identical sheets of mid/low quality stainless steel and put one in each pot. Would the sheets rust at the same rate? If not, which would rust quicker? Why?

If you can help me out with this, please be remedial as possible with the why portion of the question. I really know close to nothing about chemistry. I actually have to google these "name the element" captcha's haha.

Thanks in advance for any responses!

[Enthalpy]

Welcome, RustAnodized!

Stainless steel, even of "low quality", shall not rust in sweet water. That can be a definition of stainless. It can corrode in seawater or compounds more aggressive than sweet water, and often does.

Corrosion is hard to predict, but my gut feeling is that these pots makes little or no change.
- From few experiments, I never saw an interesting change of corrosion rate through the electric contact between normally pure metals. I suppose it matters in batteries because these use very pure or protected metals. Without a contact, it must matter even less.
- Anodized aluminium (of proper alloy, which corresponds roughly with brilliant anodisation) shall not participate in reactions with water.
- These metals would suggest a "sacrificial electrode" of aluminium protecting iron, but neither the steel nor the anodised aluminium shall corrode, so let's say nothing happens.

Since good stainless steel (18-10 is a normal start) is cheaper than low-quality one (rare!), I don't see why to bother. In mechanical construction, I like to use martensitic alloy like the X30Cr13, which isn't as corrosion-resistant as the austenitic 18-10, and never saw corrosion in open-air rainy conditions.