Rusted stainless steel castings
Rusted stainless steel castings
(OP)
I have 304 stainless steel castings that are developing rust. They have already been pickled (how and in what, I don't know). Can anyone guide me to the corrective action ? I've heard of passivating, sandblasting, electropolishing, and at this point, I don't have a clue as to the most cost-effective solution. Also, directing me to anyone that does this corrective operation is also appreciated.





RE: Rusted stainless steel castings
The resolution is to remove the iron by pickling it off; some call it passivation. Use nitric acid, phosphoric acid, citric acid, etc. Specific instructions can be found at websites like stainlesscenter.com.
RE: Rusted stainless steel castings
RE: Rusted stainless steel castings
RE: Rusted stainless steel castings
RE: Rusted stainless steel castings
This may be too late but there may be another reason the castings are rusting. If the chemistry is not controlled or final heat treatment is not correct, an excessive amount of ferrite may be present in the casting.
grayseal
RE: Rusted stainless steel castings
RE: Rusted stainless steel castings
RE: Rusted stainless steel castings
Have you tried shotblasting with Stainless steel shots or Grit after heattreatment and before passivation?
I think that might help.
RE: Rusted stainless steel castings
Dan Englebert
Technical Manager
Imagineering Enterprises, Inc.
South Bend, Indiana
or their web site for more information about pickling/passivation.
RE: Rusted stainless steel castings
RE: Rusted stainless steel castings
In short, control your processes, or add cost.
RE: Rusted stainless steel castings
Are you still there? You have been given lots of good advice (although even SS grit blasting is dubious).
My questions:
1) What is the environment & application?
2) How long did it take for the rust to appear?
In some environments, regular washing is necessary to remove dirt, salt and air pollution fallout in general.
The Coastal Corrosion Technical Bulletin is helpful in both the initial treatment and the maintenance of SS to avoid rusting. http://www.assda.asn.au/Teastain.pdf
RE: Rusted stainless steel castings
Section 7 (Inspection after Cleaning) gives a couple of tests for detection of iron contamination. We have used the Ferroxyl Test very succesfully on titanium alloys.
Bruv