Passivate after hardstamping stainless steel
Passivate after hardstamping stainless steel
(OP)
I have received a number of parts that I need to stamp heat numbers to for traceability. The stamps are made of an unknown material, but do not seem to be corroded in any way, so perhaps they're stainless too, but I doubt it.
Should I passivate the stamped area of the parts after I have hand stamped them - they are made of UNS 32750. I have on hand Nitric Acid to perform the passivation. Service will be submerged in sea water.
Thanks all.
Should I passivate the stamped area of the parts after I have hand stamped them - they are made of UNS 32750. I have on hand Nitric Acid to perform the passivation. Service will be submerged in sea water.
Thanks all.
RE: Passivate after hardstamping stainless steel
Why not?
If you have the capability and the cost is minimal, passivation is always better.
RE: Passivate after hardstamping stainless steel
If there isn't risk that this stuff corrodes badly due to the stamping, I will leave it. A little bit of surface rust is fine, but these parts are being replaced due to their legacy parts suffering from crevice corrosion on the threaded elements, hence my concern. The stamping I am applying is to an external surface with no risk of confined spaces for crevice corrosion to initiate, so I doubt it's a problem, but if anyone on this forum has direct experience with something like this it would be appreciated.
Don't have a problem doing it, but would rather avoid if it's not necessary.
RE: Passivate after hardstamping stainless steel
Docks are one of the most challenging environments. They combine salt spray with evaporation to create extremely high chloride concentrations. There is no rinsing to remove contaminants from surfaces. Stainless steel will always rust so a little bit of extra ferrite on the surface probably isn't going to have any noticable impact when weighed against all of the other problems.
RE: Passivate after hardstamping stainless steel
It isn't so much the stamps as what surface debris could be imbedded.
Or if the stamps have ever been used on steel you would imbed that material.
You have altered the surface condition, passivate.
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P.E. Metallurgy, consulting work welcomed
RE: Passivate after hardstamping stainless steel
RE: Passivate after hardstamping stainless steel
RE: Passivate after hardstamping stainless steel
Dot-peen parking [small dot impressions, shallow or deep].
Acid-Etch marking
Laser-etch marking
As far as passivation is concerned... if You really see the need... AMS2700 Has method I and Method 2...
Method 1 - Passivation in Nitric Acid, types 1-to-8
Method 2 - Passivation in Citric Acid
Method 2 is NOW preferred by USAF, where practical, because it works for most SStl and is environmentally 'friendlier'.
Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
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RE: Passivate after hardstamping stainless steel
Whereas room temp 40% Nitric always works.
When we needed to spot passivate we used the disposable diapers and cut a piece a bit larger than our area and then soaked it with acid and applied it. Let it stand 15-30min, remove and place in disposal bag, and then rinse the area.
Very little waste.
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P.E. Metallurgy, consulting work welcomed