I frequently need to discriminate between 304 and 316 stainless steel which cannot be done by eye.
304 SS has 18% chromium and 8% nickel
316 SS has 16% chromium, 10% nickel and 2% molybdenum
How can I do a chemical assay to discriminate between them and ideally identify their precise composition to 1% or better accuracy? I assume the basic procedure is to create a solution, then do a titration of some kind.
If the first step in your answer is... "dissolve the sample in acid," be aware that stainless steel is pretty resistant to most acids and I need a procedure that will work within 24 hours.
Also, please no answers like "use an xrf machine" or some surface detection technology. I need a chemical process that assays the whole sample, not just its surface.