I noticed on 1 of my stainless steel spoons that a film of Iron(II) oxide(which is a black rust) formed. I have been taught that stainless steel will not rust. So why would a stainless steel spoon be oxidizing?
But the 18/10 chromium-nickel alloy is austenitic. Which means it's not, or very weakly, magnetic. If your spoon is attracted by a magnet then it's a ferric 18/0.I know that nickel is a magnetic metal just like iron is so a magnetism test probably would not help determine whether it is Iron(II) oxide like I thought it was or whether it is Nickel(III) oxide.
18/10 is the chromium/nickel content (the 10 is actually an 8, because reasons). Such ssteel is classified as the 300 series. The difference between the more common 304 and 316 is in other additives, that make 316 especially corrosion resistant, but about one-and-a-half to twice as expensive (iirc). If your source says 316 is also used for cutlery, then who am I to say otherwise. It just seems unnecessary for the regular kitchen environment to use marine-grade steel. If I had to venture a guess, I'd say you may find this grade in those expensive, 'high-end' utensils marketed to the more snobbish parts of the population.I looked up the grades of stainless steel and it said that 316 is used often in cutlery(so your common kitchen utensils) and that 316 is the same as 18/10.
See here:But why would 18/10 steel be weakly magnetic if it is at all magnetic?
for starters: http://en.wikipedia.org/wiki/Austenite#StabilizationThat says that gamma iron occurs when the temperature of the iron is 1000K or 730 C. That is the curie temperature of iron. And austenite is a form of gamma iron. But how does the nickel along with the chromium keep the iron in its gamma allotrope even after the iron has cooled down?
If you still have some of that rust. Scrape it off and heat it on a gas stove (while being careful not to blow it away) FeO will turn to a red Fe2O3.I noticed on 1 of my stainless steel spoons that a film of Iron(II) oxide(which is a black rust) formed. I have been taught that stainless steel will not rust. So why would a stainless steel spoon be oxidizing?