Slag compaosition for welding HA steels like SS and inconels 2

[sayee1]

Does anyone have on the data about the slag compositions for the welding of materials specified above with say SMAW or SAW processes. I do know from my very little experience that slag is a complex system of oxides and I am sure a simple chemical analysis would hardly help me get the constituents/compounds present! For just information, how is slag normally analysed for e.g. in steel making process?
Again, I do think it is not water soluble, but is slag formed for welding as above soluble in water? The reason I am asking is we are proposing a "golden weld " of inconel to inconel using SMAW for the root as well as filling and capping. This is because the golden or tie in weld cannot be purged and the slag protection for the weld root in that case works better against a TIG root with no purging. In that case the client is asking about the solubility and the harm of leaving the salg as is after welding? Any comments?
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!

 

[Metalguy]

Sayeeprasadr,

I'd get you some flux compositions, but I won't be back at work for a few days-going to visit Florence Italy and Elba Island, where Napolean was in exile for a bit.

But I am quite sure that the slag after welding is NOT water-soluble. However, you should get almost 100% metal (Inconel) on the pipe/whatever ID-the slag always seems to stay on top of the weld metal.

I'm sure you're well aware that Inconel isn't real easy to weld, and the slightest amount sulfur (oil) or lead will crack it for sure.

 

[sayee1]

Metalguy,
Thanks for ur response, only one clarification, you mention flux compositions. I have some details available on the same. What I am interested is the slag composition in addition. I am aware of the difficaulties of welding inconel (due to the higher Ni %, the viscosity of weld metal is higher and fluidity lower for one) and I have worked on inconel welding and consumable development for wide range of applications like welding of HK40 reformer tubes to welding of 9% Ni steels to welding of inconel 6625 and 8825. In addition to the welding development and standard tests, I have done quite a bit of A262(absurd but one client specs asked for A262 Pr B for inconel welds) to G48 to galvanic corrosion for inconel welds. Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!

 

[GRoberts]

"Welding Metallurgy" by Linnert says that the slag is compounds like oxides of Ca, Mn, Si & Al, that do not dissociate easily at high temperatures and are not reduced by molten iron.

"Welding Metallurgy" by Kao also has some good info on slag-metal reactions, the results of which would be the slag forming constituents. I do not have that one handy though.

Unfortunately, the information contained in most of the information refers to steel, so it there are probably significant changes when relating to Ni based metal. You said that you know the constituents in the flux, so if you can find the appropriate reaction for each constituent, then the flux must be made up of the products of the reactions.

I think the difinitive test would be though, to run a bead on plate and place it in the service fluid without removing the slag, and see if the slag dissolves, or test the fluid for contaminants. Is this possible?

Regarding steelmaking slag, do they actually analyse the slag, or do they just know what each slag constituent does and analyse the molten metal after reaction with the slag?