How many amps to use for this...?

[n0v0s]

Hi,

I'm welding 5mm thick mild steel tube to what I think is a cast steel manifold. Please see pictures, I've bevelled the mating surface of the tube and manifold as best as I can. I

I should probably have left a bigger gap between the two pieces to allow full depth penetration. There's a small gap where I can see light through outside when shone from inside the manifold. Is this ok?

The welds shown were trialed at between 100-120amps just to test. Was only meant to tack a few spots but got carried away.

Clearly the tubes got very hot, as seen by the multi coloured surface. But I'm concerned about not getting enough penetration through either materials.

What amps should I be using? Does penetration look ok? Filler rod 1.6mm A15. Tungsten is 1.6mm 2% lanthiated. No 6 cup with between 8-10 LPM according to the regulator. Not got a pea shooter or flow meter to check.

Electrode looking smokey black, especially with big stick out to get to inside welds.

I know the welds don't look very asthetic, but as long as it holds I'm not too bothered! Was hoping maybe can get 2mm material depth penetration from outside, and maybe 1mm from inside.

Should I do a second pass around the outside just in case?

Cheers all

 

[n0v0s]

Better to be too hot than too cold, right? I don't want to be cooking the welds though and risking poor penetration due to inadequate shielding. Or warping the bloody thing as I continue assembling the other pie cut segments.

 

[chris pruteanu]

That manifold looks like cast iron to me...do you hear it cracking as it cools down?

 

[n0v0s]

That manifold looks like cast iron to me...do you hear it cracking as it cools down?

Bloody hope not! Oh damn, in my haste I didn't do the "spark" test or try drilling it. To be honest, I wasn't paying much attention to tinkling /cracking sounds. Was too hungry and eager to get back in! Doh!

I suppose if it's cast iron then that welds will have visibly cracked by now? Or is it not that clear cut?

 

[BigOz]

I'd momentarily puddle a tiny spot on an edge or outside corner somewhere inconspicuous then see if that spot can be cut with a file, if it won't I'd expect a challenge going forward.

 

[n0v0s]

I'd momentarily puddle a tiny spot on an edge or outside corner somewhere inconspicuous then see if that spot can be cut with a file, if it won't I'd expect a challenge going forward.

Yh it spot welded rock hard and spark test concluded it is indeed cast- ordered NiFE-55 rod. Bbq'd the assembly on coal, then attacked with blow torch every other pass and stuck back on coal with sand let slow cool over night. Ended up doing 2-3 passes inside and out. Not the prettiest. But not bad.

No cracks this am. But then again, the a15 didn't show any cracks despite no pre heat. Might well be one of the more forgiving forms of cast iron. Only time will tell.