Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Info On Nb Nitride formation with ERNiCrMo-3 & Duplex SS

Status
Not open for further replies.

weldmete

Materials
Joined
Dec 11, 2002
Messages
9
Location
US

I've heard that failures have occured when welding duplex SS to dissimilar metals using ERNiCrMo-3 due to Nitrogen reduction in the fusion line, because Nb bonds with the Nitrigen. Is this true?
Does anyone know of any published articles on the web that bears this out?

Thanks,

Weldmete
 
I don't know of any specific web articles on this, but it does make sense. In micro and low alloy steels, Nb is considered a nitride former. Nitrogen is also an inerstitial element, so has a high diffusivity, so it would be able to travel at the higher temperatures.
 
We've commonly welded duplex to carbon steel and duplex to Alloy 625 with ERNiCrMo-3 and have not had any reported cracking incidents. It is known that creep ductility is adversely affected when in high temperature service due to presence of Niobium carbo-nitrides.

 
There is no question that nobium forms carbides and nitrides. The amount of nitrogen, carbon and niobium present will determine what forms ( NbC or NbN ) and at what temperature. The loss of nitrogen in solution will definitly alter mechanical and corrosion properties. Whether they have contributed to a weld failure is something you haven't provided enough facts on for conjecture.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Back
Top