Corrosion on cast steel
Corrosion on cast steel
(OP)
We are having a larger stock of valve bodies made of cast steel CF3M and corrosion appears due to humidity in our warehouse which can not be decreased. What are you proposed to protect the corrosion? medium should be effective nit exensive and easy to use? Any sugegstions?
How do you remove corrsion from cast steel surfaces?
Thx
J
How do you remove corrsion from cast steel surfaces?
Thx
J
RE: Corrosion on cast steel
To remove corrosion a quick dip in phosphoric acid will remove light corrosion. Follow up with a rinse in water treated with the aforementioned diesel engine coolant treatments to prevent flash rusting as it dries. The diesel treatment is a supplemental coolant additive or 2000 series coolant treatment mixed 16:1 with water. The active ingredients are sodium silicate, sodium borate, and sodium nitrite. I'm sure there are specific products for your application but I have these abundantly available and they work for me.
RE: Corrosion on cast steel
If these are only on the cast surfaces maybe you should have some words with you supplier. The casting should have been annealed, blasted (usually grit or shot) and then passivated (hopefully in Nitric acid). The raw castings should never show rust spots.
1. If you have done any machining make sure that you coolant is well filtered.
2. If you do any 'touch up' with wire brushes, flap wheels, or files make sure that these are only ever used on stainless steel. (and make sure that the brushes are 3xx SS)
3. You can remove Fe easily with acids, the safest is a product called CitriSurf which is citric acid based. (I have bad experience with a quick dip in anything other than nitric acid, but that is more difficult)
4. Any of the corrosion inhibitor companies will sell Rust Preventive (RP) oils some of which are designed for Stainless Steels, ask.
5. Use nylon slings for lifting, rest only on wood, cardboard, or plastic, use flange face covers (also minimizes mechanical damage). No chains, no metal forks, no steel tables or pallets.
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P.E. Metallurgy, consulting work welcomed
RE: Corrosion on cast steel
Best regards - Al
RE: Corrosion on cast steel
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P.E. Metallurgy, consulting work welcomed
RE: Corrosion on cast steel
RE: Corrosion on cast steel
RE: Corrosion on cast steel
luis
RE: Corrosion on cast steel
Storing in dry air will hide the problem, but when they get to the customer they will have rust spots.
Find and fix the root cause.
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P.E. Metallurgy, consulting work welcomed
RE: Corrosion on cast steel
Were they pickled afterwards? They should have been in Nitric Acid/HF.
Avoid contact with and steel, or accept that you will have to acid passivate to clean them before storing.
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P.E. Metallurgy, consulting work welcomed