Corrosion resistance of Nickel Plating vs. 304 Stainless Steel

A. Yes and no.
400 series has a good bit iron in it, so is far less corrosion resistant than say 300 series.
Nickel is resistant to many chemicals, but not all, so it depends on its end use. Also it depends on the nickel thickness. Remember that plating can be scored-through by accident in some applications, whereas SS cannot.
400 series is typically used in knives and nickel plating would be a poor application because of the knife being sharpened. Some knives are still built of high carbon steel, but not many.

A. Hi John. If the nickel plating were truly pore-free and pinhole-free it might be fine, but I doubt that it would be. And what if the article gets scratched through -- is that a reasonable possibility? It's hard to say what is the best material in the abstract, but I'd guess if it doesn't see more than 1% NaOCl the type 304SS is probably okay for most purposes. I think the drums of washing machines are only 4xx stainless, and they are probably exposed to similar sodium hypochlorite concentrations.

Regards,

A. I would definitely not use the nickel plated brass. My experience was failed part on more 5% hypochlorite after 6 months.

A. I would recommend using 304 stainless steel. Hypochlorite will attack the nickel more readily that stainless. As Ted says, the nickel must be pore free, otherwise the chloride/chlorite ions will start to attack the brass, resulting in dezincification of the brass and failure of the component.