Can anyone give me some more detailed information on the phenomenon of carbon contamination of P91 material when it comes into contact with carbon steel (e.g. when carbon steel is used to lift P91 material, some of the carbon steel material gets embedded into the P91 material). Specifically, what happens to the microstructure of the P91, and what are the results of this kind of contamination?
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Contamination of P91 Material By Carbon Steel
- Thread starter pjdobson
- Start date
EdStainless
Materials
It isn't carbon contamination, it is Fe contamination. The embedded Fe in the surface corrodes very easily. These locations can provide sites for the easy initiation of corrosion attack.
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- Thread starter
- #3
EdStainless: Thanks for the response. It is also possible that, if the contamination takes place prior to fabrication and PWHT that the carbon can react with the Cr in the P91 forming chromium carbides during PWHT at the contamination sites and alter the P91 material property?
- Thread starter
- #4
I had never heard of carbon contamination of P91, but that doesn't mean it isn't possible. Sounds like the fabricator is on a fishing expediton to deflect criticism of their fab procedures and blame the erector.
What sort of microstructural changes have you detected? If you completed a hardness traverse and plastic film replication and found ferrite instead of martensite, then it is not carbon contamination, but fabricator education that is the root cause.
What sort of microstructural changes have you detected? If you completed a hardness traverse and plastic film replication and found ferrite instead of martensite, then it is not carbon contamination, but fabricator education that is the root cause.
EdStainless
Materials
The only chance to add carbon is if the parts are heavily contaminated with oil or grease going into HT.
I would be more worried about oxidation/decarb damage in this grade also.
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Rust never sleeps
Neither should your protection
I would be more worried about oxidation/decarb damage in this grade also.
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Rust never sleeps
Neither should your protection
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