Stellite 6 hard facing on inconel 617 PQR?

[MManger]

Looking for input.

I’m working on a PQR for Stellite 6 hard facing on Inconel 617, I’m running into problems with the destructive testing. I’m finding indications in the hard face layer, they are not typical through layering cracking. They look more like an inclusion or type of shrinkage (very small .5 mm). The Indications are found in the cross section of the hard facing, nothing found when prepping the as welded surface to the finished surface.

This is the welding data:

Stellite 6 on Inconel 617
Base Metal thickness .250” and 1.0”
Desired Build up: .096” as welded, .076” finished deposit.
Preheat: 600F
I.P. temp: 600-800F
# of Layers: 5
Process: GTAW, 100% Argon, DCE, .125” electrode
Cooling: Slow cooling in thermal blanket 150F/hr
Destructive testing: Machine the as welded surface (PT), then EDM the Cross section (locating the indications at this point of testing visually magnified and PT, Have not etched the cross section as of yet).

Thank you for any thoughts or opinions!

Mike

 

[metengr]

MManger;
The weldability of Inconel Alloy 617 is excellent. At this point, you need to have a metallurgical lab evaluate the cross section of the weld deposit to determine if this is porosity or microcracking in the Stellite 6 weld deposit. If this is porosity, it could be shielding gas problems with Argon or surface contamination. Did you adequately clean the surface of the Inconel 617 before hardfacing? This is critical. I don't see any other problems off hand with the welding data you provided.

 

[MManger]

Thank You for your responce.

More infor on the indications:
Once the indications were found (1 per sample), we took two different samples and milled off .004" - .010",then polished,and indaction was removed.

The surface area of the inconel 617 was prepared by using a soft sanding disc, but the stellite layers were not cleaned between passes.

As for the Argon, two different flow rates and two different bottles were used (35cfh and 45cfh).

Could there be a problem with the electrodes being contaminated if the box was not brand new (bare/solid)?

Could there be a problem with the EDM process?

What type of information should I be asking for from the metalurgist?

Thanks
Mike

 

[EdStainless]

You are right to question the electrodes and the Ar. Bottled gas can be variable in quality.

Ask to have samples examined for indications of contamination associated with the indications, oxides are most likely but others are possible.
From the morphology of the indications they should be able to identify if they are related to shrinkage or voids.

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Plymouth Tube

 

[Guest102023]

I agree with those above, it sounds like a welding process issue. But a lab needs to assess the discontinuities before anyone can pronounce.
Higher-grade Argon is available, which I would recommend anyway for most expensive CRAs.