Multi pass mig welds

[Jim Davey]

flux cored wire on a nice big MIG would be best, but in this instance it's not available so stick really is the only way.

 

[BrokenBiker]

When you say big, how big do you mean? I know flux core burns hotter but is there that much difference?

 

[Jim Davey]

Same metallurgy as stick but faster. And for what you're doing it would be in the 250-300A range

 

[Richard.]

Flux core rutile wire is a gem to weld with. As Jim says the composition is very similar to a rutile electrode. Difference been the flux is on the outside of an electrode and on the inside of the rolled strip on the wire. Where it really comes into it's own is out of position. With solid wire dip transfer is needed for V up to keep things stable and under control. With the fcw you can weld vertically up in spray transfer. I've done quite a bit with it and it's lovely on open root stuff onto ceramics. It's not much good on your mig though as you need more power as Jim said but a good bit of info none the less.

 

[BrokenBiker]

Again, interesting to know. I used flux core in my pathetic mightymig for ages and it was crap but I suspect that was mostly down to the fact that the welder itself was also crap and I probably wasn't the best lol.

 

[Richard.]

Your probably referring to gasless flux core self shielding rubbish. I'm referring to an industrial grade gas shielded rutile flux cored wire. They weld nothing like the hobby gasless stuff. They also run nicely in positive polarity.

 

[Rrunnach]

You mean duel shield, Richard?

 

[BrokenBiker]

Didn't realise you were talking about dual shielded flux core, I have welded wth that once, had some in to trial where I did my apprenticeship and had a play with it. Can remember it being very nice to use compared to the crap I had at home.

 

[Richard.]

You mean duel shield, Richard?

Yep. That's it mate. Cheers.

 

[Rrunnach]

Used it a handful of times, all 316L stainless, same spiel,run before the flux ping's off and, finds a bare bit of skin!

 

[Richard.]

Used it a handful of times, all 316L stainless, same spiel,run before the flux ping's off and, finds a bare bit of skin!

Ha ha yeah I feel that. It's not so bad with the rutile FC wire as that tends to just lift but the stainless yeah that stuff would spit it right at ya. 316 electrodes are the same. They always seem to find the tiny bit of skin on show.

 

[Ideator]

Side wall fusion will be very minimal as that thick cold plate sucks away your heat.

What if you used a flame to heat the joint before starting the weld? Would that compensate for heat lost from the bead through the cold metal?

 

[sapperb]

I found that using a thick block of aluminum behind the area you are welding (if possible) works great. As we all know, welding thin metal SUCKS!!! so the aluminum with draw the majority of the heat off the metal and allow you more success in the welding path and less chance of burning through..