Thread: Stick Welding and slag
13th Dec 2013, 07:50 PM #1
Stick Welding and slag
Hi, I'm at the point that I fairly comfortable laying down a good neat bead with a stick welder.
My question is ...Sometimes the slag lifts off by itself and at other times, actually most of the time the slag takes
quite a bit of effort to get off. Even so, the weld underneath is still quite neat. What can I do to get the slag to remove itself?
I seen a guy on Youtube, welding tube and all he had to do was scratch it or wipe it with a wire brush and it just fell off.
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13th Dec 2013, 09:24 PM #2
I'm not an expert at this, but it will depend on the type of electrode used (what sort of slag it produces) and also on having just the right heat input on the weld (feed rate, amps and so on).
I do like it when it does that though...
I find that my slag is more likely to chip off cleanly if I use the chipping hammer on the edge of the weld and trying to be as close as I can to a tangent to the base material rather than hitting square to the weld surface. The bit that the slag wants to hang onto most is the junction between the weld metal and the base material.
15th Dec 2013, 03:53 PM #3
Yeah, it's generally an indication of how well you just welded I find. Get things wrong and it'll stick. Get it right and it peels off by itself.
15th Dec 2013, 07:15 PM #4
Clean base metal helps (not rusty) and avoid undercutting as the slag will catch on the undercut even if it's a tiny amount. The slag will peel off better on a weld that has been run in a straight line rather than weaving... I guess it's because the ripples in the weld are smoother? I'm not sure. As the others have said, peeling slag is an indicator of good weld settings. Oh yeah... the rod type: 6013 is a great one for one-piece slag.
15th Dec 2013, 08:11 PM #5
I think it tends to be a function of the profile and edges of the weld - if it's a nice consistent profile with clean wetting at the edges then the slag will detach easily as it cools and contracts.
16th Dec 2013, 02:15 PM #6
Thanks guys. So it does seem to come down to technique.
That makes sense because the peeling off never seems to happen with 2.5mm,
but often happens with 3.2mm.
I've been welding 6mm steel, so I weave a bit with the 2.5 and a lot less with 3.2s.
And also I might be running the 2.5s a bit hot, so it's all making sense now.
Thanks again guys.
28th Feb 2014, 07:04 AM #7
I've certainly found different rods give different results when it comes to slag removal. My beads are generally reasonable looking but just the smallest amount of undercut seems to stop the slag coming off easily.
A rod which seems to give very nice tie-in is Satincraft 13 (detested by many LOL). I use Kobe RB26 a lot of the time and have a hard time getting zero undercut, but they seem to have a bit more "bite" and generally make arc welding easier for me. Plus I like them for vertical up welding whereas with Satincraft 13 it was impossible.
5th Mar 2014, 08:53 PM #8
One of the bigest revalations in welding to me has been....clean the surface to be joined.
I have got into the habit of grinding every edge and face I weld.....I use a flap disk rather then a hard wheel.
I know because a stick welder will plough thru all sorts of crap and keep going...there is a tendancy to thing a clean surface is no so important....getting that clean surface can make an inprovement in every thing you do.
If the surface is dirty..a MIG will spit and fart or just refuse to work at all.
The poor old stick....will just weld...but the frustration comes later..when the weld has not been smooth, there is slag inclusion or the slag just wont come off.
I agree that the old Satincraft 13 is one of the most forgiving for the amateur....I've burnt a few boxes of em..and they seem to have slag that just curls off...if all is well.
I have not done much stick since the MIG arrived...( God bless the man who invented MIG)...but the last lot of rods I baught where blue stripe ( cant remember the brand)......they ran like hot chocloate.....they did sound more crisp.....and made the satincrafts look sad.......but they sill has slag stick when things did not go right.
OH...those rods you are using....they are fresh and dry?......have you got a big long lunch box for your rods.
Decor do a long thin lunch box that suits.....or pinch mums celery storer.
cheersAny thing with sharp teeth eats meat.
Most powertools have sharp teeth.
People are made of meat.
Abrasives can be just as dangerous as a blade.....and 10 times more painfull.
5th Mar 2014, 09:12 PM #9
I use Grahame's method of lengths of 90mm pvc pipe with a glued on cap on one end and a screw on cap on the other.
9th Mar 2014, 08:56 PM #10
Look at how the slag comes off a flat butt or fillet bead. It curls up because it contracts.
Notice what is pretty typical for these slag covers that just self peel away.
- Parallel edges
- Consistent height of bead.
- Drag angle
Those features comes about by consistentcy in the welding technique
- Traveling at the same welding speed
- Holding at the same arc length.
- Angle of electrode to the plate- Drag angle-
They are little things within themselves but when taken as a whole ,have effect on what the weld bead looks like.
The arc travel speed shapes bead profile,as does arc length and if keep the same for the entire bead,the bead becomes parallel and with a clean plate surface will peel away.
Holding an arc length to a consistent height through out the duration of the bead is important as arc length has an effect on arc voltage .Shorter is better -about a wire core diameter from the plate surface.Better bead profile.
Drag angle is kept consistent by locking the wrist during welding - not pivoting as the weld progresses and the electrode length decreases. It is all part of the technique the prosuse daily without thinking about it.
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