Wheel Arch Welding Problem

[Rust Warrior]

Hi all.

I've hit a hurdle in my work van welding on the wheel arch. I actually think I know what's causing the issue, but not entirely sure on how to sort it. I figured some of you may have encountered this as well and may know a quick solution.

For perspective and reference, I'm using 0.8mm flux core, 55 amps and 1.2mm replacement mild steel metal.

The problem is that the new piece won't fuse to the original wheel arch metal I'm trying to weld to. I've ground the mating surfaces on both sides, back to shiny metal. What's happening is the arc keeps "blowing out" and it's leaving black marks, smoke, a few little flames, and hardly any welds. Just to test my theory, I ground back some paint further up and tried laying a weld down on it. Guess what? I got the exact same problem!

I looked at the rotten piece of wheel arch I chopped out, and it seems to be bonded in a triple layer with some kind of black bonding. I suspect this bonding is the source of the impasse because it's not allowing weld penetration, or is effecting the electrical current in some way. The earth clamp is attached very closely to where I'm welding to (or trying to).

I just wondered if I'm missing a trick here, or whether it might need the inner 2 metal layers ground away, a different type of welding (TIG, or MMA), or whether I'm genuinely up a creek without a paddle and it'll need a complete wheel arch.

Thanks for any tips.

 

[tom2207]

your welding too cold and your gaps a bit wide , you have set you self a tough task ... check polarity and if its ok add heat , but make sure you have fire watch and some wet cloths , ,a spray and / or an extinguisher to hand ,,,
the part you cut out would probably have cleaned up ok , but its a bit late now ,,,, maybe practice on the bench with a few off cuts first so you get your settings and technique perfect before starting on the van.

 

[Rust Warrior]

your welding too cold and your gaps a bit wide , you have set you self a tough task ... check polarity and if its ok add heat , but make sure you have fire watch and some wet cloths , ,a spray and / or an extinguisher to hand ,,,
the part you cut out would probably have cleaned up ok , but its a bit late now ,,,, maybe practice on the bench with a few off cuts first so you get your settings and technique perfect before starting on the van.

The gap wasn't like that, it was tight up against the original metal. I was using magnets to hold it steady. I've been practicing already but there's that point where you just have to bite the bullet and go for it. If I up the amps, I'll blow holes in the new metal.

 

[500e]

Contamination what /where is the black stuff ?what is it looks like some bitumin product
Pic 3 seems to have a lot of layers

 

[Rust Warrior]

Contamination what /where is the black stuff ?what is it looks like some bitumin product
Pic 3 seems to have a lot of layers

It's between the layers of metal.

 

[500e]

If it is Tar, Bitumin, some sort of paint, seam sealer, it will produce a gas as it heats

 

[tom2207]

practice more ,,, not being harsh , but thats the truth , at least you have 1.2 steel, that works as a heat sink so it helps , personally I dont use flux core , do you have variable adjustments on your welder or just that old 4 position switch set up.

 

[Rust Warrior]

practice more ,,, not being harsh , but thats the truth , at least you have 1.2 steel, that works as a heat sink so it helps , personally I dont use flux core , do you have variable adjustments on your welder or just that old 4 position switch set up.

I can adjust the amps, and there's a display that shows wire gauge, and MIG or MMA mode.

 

[tom2207]

do a few welds on the bench and lets see how they look , see if we can work from there . a fair few folk here use a similar set up , as I mentioned , I dont , but I do a lot of this kind of work. It looks easily repairable without needing an arch though ,,, that sounds a tad extreme

 

[MetalMonkey]

Its a seam sealer/PU sealer, and yes it will contaminate the weld, which combined with the other issues already mentioned explains the difficulty.
Your gaps need to be much tighter, also looks like you are blowing through the metal - the trick with that thin bodywork is hot and fast tacks that barely have a chance to heat it up.
I've no real experience with flux core, but I'd suggest gas might also give you a much easier time as well.

 

[Rust Warrior]

Its a seam sealer/PU sealer, and yes it will contaminate the weld, which combined with the other issues already mentioned explains the difficulty.
Your gaps need to be much tighter, also looks like you are blowing through the metal - the trick with that thin bodywork is hot and fast tacks that barely have a chance to heat it up.
I've no real experience with flux core, but I'd suggest gas might also give you a much easier time as well.

The gap wasn't that large. The weld attempts failed so the metal was dangling. It was tight up against the bodywork when I was welding.

 

[mr haynes]

Start at the beginning.....
Have you tried to run a bead on a clean bit of new steel?
Eliminate any machine issues first

 

[Nick DV]

Start at the beginning.....
Have you tried to run a bead on a clean bit of new steel?
Eliminate any machine issues first

Great suggestion, but I suspect it’s a combination of everything previously mentioned.

 

[tom2207]

your 1.2 isnt zintec is it by chance ?? try the bench thing as I suggested and lets see what the starting point is ,

 

[mr haynes]

I'm sure there are a few on here with the scars to prove it is possible to mig weld less than clean steel together.
Cheap mot sill and floor patch bombers were all the rage in the past, close to being an art form

 

[Wedg1e]

Just to further muddy the waters, strong magnets near a MIG torch will affect the weld too. One you get some tacks on (other issues aside), whip the magnets off.