Basically I have an interview on Friday and I know they are having a problem welding inconnel to carbon steel (I don't know the grades, but they are to be used off shore and sub sea), they are having up to 5% dilution problems with the inconnel.
Has anyone ever come across this or a similar problem?
It would be a good topic to talk about at the interview and i'm struggling to find anything from the web
5% dilution sounds like a submerged-arc SAW overlay. A 'colder' weld process will decrease the dilution. I would try GMAW / MAG in the short-circuiting mode. It has the least penetration, and thus least dilution, of the common welding processes.
Yeah they are using sub arc (I should have said before). They make sub surface christmas trees and apparently spent a fortune on getting 4 very expensive machines so I would imagine they will try like hell to make them viable.
I've only seen pictures of these christmas trees, so i'm not sure if they used MAG and then got these machines to help with the work load or had old sub arc machines there and replaced them.
Not used much sub arc, could polarity be a factor? ie using AC instead of DC?
AC is an excellent idea. Hopefully, the new machines have that option.
SAW is run DC-Electrode Positive, putting the bulk of the heat on the wire [and flux pile]. Going to DC-Electrode Negative would put the bulk of the heat onto the base metal, a VERY bad idea. I expect that this would more than double the dilution rate.