Iron dilution in Incoloy 625 cladding on CS pipe
Iron dilution in Incoloy 625 cladding on CS pipe
(OP)
I have observed a unique problem with respect to dilution of Fe content while welding over laying 3mm Incoloy 625 on API -5L pipe. After over laying it was observed that Fe conten has gone up to 8% in the over laid layer. Fe content as indicated in MR 01-75 FOR Incoloy 625 is 5% max. Now can any body suggest whether this can be accepted as material shall have to meet as per client's requirement.





RE: Iron dilution in Incoloy 625 cladding on CS pipe
What was the result in the qualification trial?
What was the Fe in the starting 625?
The real issue is corrosion resistance. The overlay is not being relyed on for mechanical properties. Unless overlay with this level of Fe has been tested then it may not be acceptable. Fe dilution is why most overlay work is done either in multiple passes or with odd alloys for the overlay.
In this case I would also be concerned with the C content of the overlay.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Iron dilution in Incoloy 625 cladding on CS pipe
See page 16
RE: Iron dilution in Incoloy 625 cladding on CS pipe
There is a clear iron enrichment zones in nickel based overlays in boiler tubes that shows up clearly when the overlay is etched using a strong acid etch (rather than an electrolytic etch). The higher iron region etches first in the metallographic sample. Does this indicate that these areas are more susceptible to corrosion? I would say that, qualitatively, the answer is yes. It is if your environment is Etchant #89 (mixed acids - Nitric-Hydrochloric-Acetic-Glycerin).
RE: Iron dilution in Incoloy 625 cladding on CS pipe
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/