I just wanted to post two pics of tungsten inclusions in inconel cladding (pic 1) and end buttering (pic 2).  we are using 2% thoriated tungsten electrodes (at least we should be).  you can see in the thorium in pic 2 (dark spots), but nothing in pic 1.  I have had both analyzed using SEM and results came back that pic 1 was pure tungsten, while pic 2 was tungsten w/ approx 2% thorium.  I am still investigating the actual electrode used on the clad to verify it wasn't a pure tungsten (it is highly unlikely this is the case).  I was wondering anyones thoughts on how we could be getting pure tungsten inclusion.  There is also a slim chance one sample was etched and the other wasn't, I am in the process of verifying this as well.  I am not sure if this would have any affect on the thorium showing up or not.  The cladding operation is an approximately 8 hr weld.  we are held to .005 max inclusions.  My thoughts were possibly the thoriated tungsten was breaking down over time exposing pure tungsten.  This is an AGTAW process and dipping is highly unlikely.  I thought someone may have some experience with tungsten inclusions on this scale.  It is also interesting how the inclusion in pic 1 almost looks like it melted. pretty interesting.  Thanks

Brett

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