Pickling & Passivation..again
Pickling & Passivation..again
(OP)
Dear all,
Here comes the Pickle & Passivation discussion again. Hold on tight.
I have stainless steels castings that have already been annealed and pickled&passivated.
Then I machined them with steel tooling (clamps etc). The pieces are relatively big so there was a high clamping force and whatever that entails regarding smearing or impregnating Fe particles on the surface.
I think that I need to passivate them. Does anybody else here think I also need to pickle?
In the ASM Stainless Steels Handbook it recommends just Nitric Acid for cleaning passivation. Nitric and HF is for welds.
Many people tell me that Citric acid can also be used for cleaning / passivation.
Here comes the Pickle & Passivation discussion again. Hold on tight.
I have stainless steels castings that have already been annealed and pickled&passivated.
Then I machined them with steel tooling (clamps etc). The pieces are relatively big so there was a high clamping force and whatever that entails regarding smearing or impregnating Fe particles on the surface.
I think that I need to passivate them. Does anybody else here think I also need to pickle?
In the ASM Stainless Steels Handbook it recommends just Nitric Acid for cleaning passivation. Nitric and HF is for welds.
Many people tell me that Citric acid can also be used for cleaning / passivation.





RE: Pickling & Passivation..again
What is the end use of the final machined castings that would require another pickling and passivation step?
RE: Pickling & Passivation..again
I just don't want any surprises like blooming etc..
RE: Pickling & Passivation..again
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Pickling & Passivation..again
I would pickle.
What worries me about machining is the risk of smeared or folded metal forming crevices on the surface.
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Plymouth Tube
RE: Pickling & Passivation..again
Machining also works-hardens a near surface layer so if you want optimal corrosion resistance that needs to go via pickling.
MH
http://www.linkedin.com/pub/luke-autry/1b/510/566
RE: Pickling & Passivation..again
Thanks
RE: Pickling & Passivation..again
I would think that it exposes base metal which has 100% chrome levels.
RE: Pickling & Passivation..again
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Pickling & Passivation..again
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Plymouth Tube
RE: Pickling & Passivation..again
26 Jun 12 18:18
Machining itself is enough reason to re-pickle if you want optimum corrosion resistance. Machining exposes surfaces which have some chromium depletion. I'm currently running a battery of tests to quantify this.
Mcquire did you ever finish your study?