Thread: Welding slag

Geoff more info needed
Metal thickness
rods being used
amps
style of weld (vertical, horizontal)
width of weld,
swing of rod.
speed of hand

and a photo?

As mentioned, more info would be good, but it sounds like you're not forming a decent weld puddle that is spanning the gap, rather the arc is jumping to one side or the other, depositing metal on each edge.

You need to watch the puddle carefully and make sure it's spreading to a decent size and settling on both edges of the weld - that might require going a bit slower, perhaps more amps, or perhaps a bit of a weave to bring the puddle right on to each side of the weld.

Garfield
Gate ? -
Galvanised ? If you did not grind the gal off the pipe/tube there's a problem.
Using a long arc on lower amps inclines the job to slag up in the guts of the bead.

If the pipe is thin wall we tend to turn the welder amps down. Low amps can result in slag inclusion.

If it tis gal ,whack a fan behind you.If you have any bronchial problems at all don't do at all.
Cheers
Grahame

He would be either using 12 or 13's they are pretty prone to it. If you got a gap you seem to get that in the centre , if you can run more amps it helps but you might burn through, and a short arc length helps you can usually see it happening in the weld puddle it looks slightly different than when you are putting down a good weld.

Thanks for the replies guys I appreciate it.

I'm using some rods that were given to me, I'm at work atm and couldn't tell you exactly what they are brand, part number etc..

I think it's more something that I'm doing wrong though to be honest.

Grahame it's not gal mate - it was painted semi bright 1.6mm wall that I brought and I took all the paint off before I started to weld. I have a little CIG-weld inverter which I had the dial set at around 55... when I had it set at 65 I seem to blow a hole in the metal pretty easy but must admit that the weld did look like it penetrate the metal and was a nice flow and puddle but I was blowing holes. As you know I'm still kind'a new to welding so I'm still making mistakes so mabye it was that my amps were a bit low you think??

Thanks
Geoff

I take it this is a flat weld, and would ask how far are you moving your rod from side to side as you run your weld
I ask this as the problem you describe can sometimes be put down to the angle you hold the rod to the job, the amount you move it and the speed you weld at

Hi Ashore,

I'm welding a 90 degree angle (joing 4 pieces of 25x25mm)

I guess I wasn't really moving side to side with the puddle more just trying to straight down the guts of it.

Clamp up with no gap for 1.6 and as rusty said you appear to be only getting a deposit either side of the joint. With internal angle welds, you'll need to slow down a little with a more accentuated weave to get that deposit to flow into one.

Originally Posted by DoctorWu

With internal angle welds, you'll need to slow down a little with a more accentuated weave to get that deposit to flow into one.

Yup, internal fillets are tricky - you need to get the arc both into the root of the join, but also touch both sides. The suggested technique seems to be to weave in a triangle - start near one side, move up and go right into the root briefly then down to the other side and repeat.

If you spend too long in the root you risk blowing through, so you need to get the timing right with a bit longer on each side to grow the weld pool and a brief time in the root to bring the weld pool into the root area and get good fusion there.

Practice makes perfect they say I've got some more to do over the next few weeks so hopefully armed with this help I have a better weld next time.

Thanks for the replies gents - really appreciate it.

Geoff,
I am with old fella on this.
Your preparation gap between the joint edges should be no greater than 1/2 the material thickness. A backing plate of copper will help.

Make sure all tacks are in place and of good quality

Start at the toe edge and weld back to the heel as there is more metal to disapate heat

See illustration.

Grahame

Originally Posted by Grahame Collins

A backing plate of copper will help.

See illustration.

How does a backing plate of copper help with welding RHS?

Hi the copper pulls some heat out of the job and will help stop blowing holes ...
Tony