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

Question

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

weldmete (Materials)

(OP)

1 May 03 12:38

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

GRoberts (Materials) · Answer 1 · 2003-05-01 13:56:08

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.

stanweld (Materials) · Answer 2 · 2003-05-20 13:43:21

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.

mcguire (Materials) · Answer 3 · 2003-05-20 16:07:56

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.

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