Why Does Stainless Steel "Rust"?
I thought it weird. My knives rusted in the USA but they don't rust down here -- even in a salt air environment. It ain't the chili... Turns out the culprit is Chlorine. Even as little chlori...
Forum Discussion
ROBERTSUNRUS wrote:
:) Hi, I have a simple test for stainless steel; If my magnet will stick to it, it is cheap, and it will rust.
well it may rust, but that doesn't mean it is cheap. yes there is stainless that is magnetic, but it in MOST cases has to do with what properties are important, not that it is cheap stainless. the most rust resistance stainless has some not desireable properties for some applications. strength, edge holding ability, brittleness etc. are properties that can be traded off for rust resistance.
There is a myth in the stainless steel industry that stainless steel is not magnetic. Or that if it is magnetic, the stainless steel is not stainless.
Magnetism and corrosion resistance are not connected. Corrosion resistance depends on how much chromium and (sometimes) molybdenum is in the stainless steel. The higher the chromium and molybdenum, the better corrosion resistance.
The magnetism myth is because the common magnetic grades of stainless steel, 409 and 430, don’t resist corrosion as well as the common non-magnetic grades, 304 and 316. You can’t expect them to. Grade 409 has 11% of chromium, which is plenty for automotive muffler systems.
