Black and white welds

[Sid]

Hi guys, could any of you tell me what's going on here.

I bought some 0.9mm sheet that was described as CR4. I'm using Argon CO2 mix (which is definately flowing) and 0.6mm solid wire.

The material seems to produce a lot of black type soot (messed up the torch in quick time) and a white powder that forms a spiders web type of coating. It all cleans off, post weld, but isn't right.

I did flap disc the material, but still got this mess (perhaps more taken off?) Anyway tried on some other scraps of steel and no white mess.

What's causing it?

 

[Bigjoe]

Im not sure but that could be galvanised or coated in some other way.

 

[Sid]

I suspect it is a galvanizing issue, but not managed to find other examples, so looking for confirmation. Thing is the sanding didn't seem to help much.

 

[malcolm]

The white stuff underneath looks like the stuff you get welding a zintec coating. There's not normally that much of it - maybe an extra-thick coating or it's galvanised.

Zintec is normally a very thin coating in a greyish colour a bit like this photo, and it is fine to weld so long as you have a little ventilation. Yours looks more silver like galvanising. You can normally see a crystal pattern if it's actually galvanised - for that you'd need to get both sides of the weld back to bare metal.

 

[Welderpaul]

I'd say thats galvanised. Cobwebs blowing around when you weld? Got the sniffles?

 

[Sid]

Doesn't look like that zintec, looks like a normal steel colour.

I've had another go at removing the coating and under artificial light it just looks like you're polishing the metal. Under natural light there is what looks like a feathering of a coating, but it's barely noticable.

Welderpaul, I was outside, and any breeze that was there was on my back, so don't think I've breathed in anything nasty. No headaches or flu like symptoms.

 

[eil]

I would say galv also, I had similar on a fan housing I welded together even though I had put a flap disk to it.

 

[Sid]

I would say galv also, I had similar on a fan housing I welded together even though I had put a flap disk to it.

I don't feel so daft now.

 

[Hitch]

Zintec i would say. CR4 should have no coating except for some ligtht oil.
Where did you buy it from?
Surelly no one that sells steel is foolish enough to get confused? They look completely different, galv,zintec,self colour... 3 different colours.
CR4 is a 'steel' colour with a bit of a sheen, galv is quite shiney, with a coating that looks like flakes, zintec is almost matt, a whitish blue/grey colour.

Although if youve flap disced it, it might be just a thin layer of galv, so same symptoms of zintec.

 

[Sparkey]

Yep definately galvanised! there's a word for those white flufs.... but i can't recall it at the mo...

 

[Sid]

Yep definately galvanised!

Thankyou Sparkey.

The only steel I can seem to find locally is for construction (rsj's and the like), no sheet. Although it has been suggested that the local motor factors may have some. Never seen any in there though.

Ended up getting some reasonably priced stuff off of fleabay. Didn't have any other steel around that wasn't orange to compare against, or notice the difference in appearance, so was not obvious to me.

It did strike me though that there was no corrosion at all on the surface, or dulling of the colour.

EDIT> will contact the seller to tell her, as someone else may make themselve ill with this stuff.

 

[BillJ]

I agree - it looks like galvanised sheet. The Ebay seller probably won't be interested in the effect on a welder unless she thinks she might be sued by an "ambulance-chaser". It being galvanised might be a selling point, though.

The only steel I can seem to find locally is for construction (rsj's and the like), no sheet. Although it has been suggested that the local motor factors may have some. Never seen any in there though.

It's quite likely they sell it but it won't be on display - it'll be in the back or upstairs or wherever they keep their stock. It will almost certainly be Zintec so be prepared for a little bit of the same effect but since Zintec only has a thin electroplated coating it will be slight (as in Malcolm's photo).

I once paid through the nose for some 1mm sheet from B&Q (Sunday afternoon panic) and that's galvanised too.

 

[Sid]

I agree - it looks like galvanised sheet. The Ebay seller probably won't be interested in the effect on a welder unless she thinks she might be sued by an "ambulance-chaser". It being galvanised might be a selling point, though.

I agree, but I've pointed out the problem and said my reason for pointing it out (to warn others). Not wishing to have a dispute. My conscience is clear.

It's quite likely they sell it but it won't be on display - it'll be in the back or upstairs or wherever they keep their stock. It will almost certainly be Zintec so be prepared for a little bit of the same effect but since Zintec only has a thin electroplated coating it will be slight (as in Malcolm's photo).

The problem with the coating was that It just looked like steel (to my eye). I know welding galv' is a health issue, I just didn't know how to recognize it. Now I do, so this has not been a wasted experience. Hopefully others will be able to spot it straight away now as well.

I once paid through the nose for some 1mm sheet from B&Q (Sunday afternoon panic) and that's galvanised too.

I did see their prices Thankfully my local B&Q doesn't sell it