Hot Crack (Longitudinal Crack) SAW Process with ERNiCrMo-3 Filler

[MrTungsten]

Hi Expert,

Is there anybody can explain Longitudinal Crack observed on SAW Process with ERNiCrMo-3 ?
Is it because hot cracking by austenitic weldment, weld shape (Weld/Depth),segregation or flux ?
In this case I want to joint pipe to pipe (X65) with Clad 625 inside, there is no option , we have to use SAW process for this joint.

Your advise and knowledge would be meaningful

Thanks and Regard's
MrTungsten

 

[EdStainless]

So the root weld is strictly 625 to 625 with the steel striped back.
And they you are building up the steel over that, with what filler?
Pictures would help a lot. and a sketch also.

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P.E. Metallurgy, Plymouth Tube

 

[weldstan]

Is the longitudinal crack in the NiCrMo-3 pass adjacent to the X65 HAZ or in the center of the weld? Where does the hot crack initiate - in root or somewhere else in the trough thickness? What is the bevel angle?

I have seen this weld made successfully numerous times without cracking; root pass with GTAW and fill with SAW in the shop. How are you making the root pass - not with SAW I should think.

 

[weldstan]

Are you making the fill pass with a single layer deposited by SAW?

 

[metengr]

I would agree with weldstan. If root single pass with SAW, this could indeed be the problem.

See excerpt from TWI below

Weld metal solidification cracking
Factors which control solidification cracking include alloy, welding process and welding conditions. For example, solidification cracking is a factor which limits the application of submerged arc welding, both with respect to applicable alloys and welding conditions. More generally, this type of cracking leads to restriction of weld shape, welding speed and technique.

 

[EdStainless]

I could see using TIG to weld the 625 root pass and then SAW to fill the outer pass.
You will not be able to weld the full wall in a single pass.
Mixing the 625 and the steel will result in poor corrosion resistance (why the 625 is there to begin with), undefined (or mixed structure), dubious properties, and poor weldability.

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P.E. Metallurgy, Plymouth Tube

 

[pradipgoswami]

Mr Tungsten,
In addition to the form factors, Carbon and Iron Dilution affects the cracking behavior of 625 overlays.625alloys inherently contains 3-4% Niobium, Nb-Carbide adds to hot cracking.
May I know what were the :
-SAW wire flux composition:
-Filler diameter used?
-The MTR report(C.A) with the same wire flux combinations.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
All provided answer are personal opinions or personal judgements only. It's not connected with any employers by any means.

 

[MrTungsten]

Hi Expert

Root Pass, hot and Fill 1 pass, we use ERNiCrMo-3 which 625 filler wire , Welding Process GTAW.

Remaining fill pass use SAW Process with 625 filler metal,

 

[weldstan]

So you are making the fill pass with a single pass? If so, I would recommend multiple passes to be used. I have made this weld successfully with multiple weld fill passes. You may also wish to open up the included angle to 90 degrees.

You still haven't defined the flux used and the crack location.

 

[EdStainless]

And I would suggest that put a step into the groove to cut back the steel a little so that the first pass is only 625.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

Agree with weldstan. Multiple pass and increase the included angle.