Stainless steel surface composition
Stainless steel surface composition
(OP)
I am running incoming inspection of stainless steel bolts, to be specific, A286. I am using hand-held XRF, so it is surface sensitive. All elements meet the requirement except titanium. Instead of 2% Ti, I am getting 1.5% consistently. I wonder if passivation/pickling process is known to suppress Ti concentration. Or any other reason why Ti is lower on the surface? Thank you.





RE: Stainless steel surface composition
RE: Stainless steel surface composition
RE: Stainless steel surface composition
2. sometimes when detecting such micro-alloyed elements, PMI equipment also shows its own error of as high as 50% (in case your operating in the mode that indicates machine error), which indicates that the machine lacks the sensitivity to detect micro-alloyed elements.
3. If the sensitivity is proven by following point no. 1 above, then you can grind off the area as suggested by Magben to expose fresh material and check the material for acceptability.
Current generation XRF machines are quite sensitive and any mismatching of results should raise doubts. Next solution should be a lab based spectroscopy.
RE: Stainless steel surface composition
But the first question is if you take a bar of A286 with a good freshly ground surface do you get 2%?
I am guessing that you don't.
Don't worry about it, this is good enough to verify that it is A286 and not some other alloy and that is all that a hand held unit is meant to do.
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P.E. Metallurgy, Plymouth Tube
RE: Stainless steel surface composition
In case anyone is not experienced with the up-to-date hand-held XRF, it is pretty accurate. You can modify zero point and gain for individual alloy. I have used hand-held XRF for years. It is not a scrap yard tool any more.
RE: Stainless steel surface composition
The light elements (Al, Si, Ti, Mg) all have much lower energy of emission and are much more sensitive to interference and blocking.
Yes, the modern x-ray tube units are nice, but you really need to know what you are doing. You can set energy level (tube voltage), and analysis time by element, if you know how to handle XRF.
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P.E. Metallurgy, Plymouth Tube
RE: Stainless steel surface composition
EDIT: I always use a certified reference block of the same grade for instrument check. Zero and Gain are adjusted, too.
RE: Stainless steel surface composition
Maui
RE: Stainless steel surface composition
A certified A286 coupon was tested for accuracy. The instrument is not off. We are a full blown chemistry lab. We have ICP-OES. We just cannot destroy this flight fastener.
RE: Stainless steel surface composition
Maui
RE: Stainless steel surface composition
RE: Stainless steel surface composition
A wet fine grind/coarse polish is preferred.
These devices also have a type standard function, so that you can shoot a known part and it will make corrections in the curve fits for that specific alloy.
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P.E. Metallurgy, Plymouth Tube