It is definitely normal mig wire, I used the exact same roll with my co2 gas with no problems. It is 0.8mm and comes in a 5kg roll, there is no surface rust and wire feed is good.
I would try swapping back to co2 but the reason i am now using argon mix is because i ran out of co2 and it seems to be impossible to get hold of these days. I am currently using my mates argon mix (i dont have my own bottle yet), i took it back round to his house for him to give the gas bottle a go on his welder and it seemed to work fine, however he didnt do a very long bead and was using stainless wire on mild steel.
Well my new reg and flow meter arrived and I first measured the gas flow rate with my mates reg, I set it up to 10l/min and tried to weld with it, it gave me the same affect as the pictures I have already posted.
I then put my brand new reg on (from weldequip) as the theory was that I may be drawing air in from somewhere which is ruining the shielding gas. It turns out that the theory of it being the reg was wrong, as i again got the same affect as before. I thought it may be the gas hose from the reg to the tip (the small white one), I have a spare hose unit (used) so I hooked up the white hose and gas valve/swan neck from that to trigger housing of the one attached to my welder. Meaning I by pass the hose of the welder so if there was an air leak this would get round it. However this has also proved to be unsuccessful.
So the only thing I can think of now is that the gas is wrong in some way? My mate bought this bottle from his gas supplier (it is a no rent supplier) and paid £40 to get it filled up, he has only just started welding so doesnt know a great deal about it, so is there a chance that the gas he purchased was incorrect?
Has anyone got any other ideas as to what the issue could be?
You said you bought a peashooter to test gas flow from the end of the torch. Did that read a sensible gas flow rate? If so is it windy where you are working?
I read 10l/min when the reg is set to 12l/min with the gas valve that is in the torch on the welder and I read pretty close to 10l/min when the reg is set to 10l/min using the spare gas valve.
This morning I went out and decided to clean off the millscale from the 3mm steel I was welding incase that was an issue. I used a flap disc and took it all off, however the issue still remains.
I took some more pictures just in case there is something obvious that I am missing:
The welds themselves look like they are well shielded, but it is a surprise that 10l/min doesn't shield much beyond them.
Part of it might be your torch angle. Looks like you have the torch angled towards the side of the weld. There shouldn't be an angle side to side, only a small (20 degrees or so) angle where the tip of the torch is angled towards the direction you want to weld. You'll be loosing quite a lot of the gas to the side, and it won't be making the welding any easier either.
I thought it looked that way to me as well Malcom. I will try and play around with the angle of my torch and I'll report back here and let you know how I get on. I really am hoping that it is down to my welding technique and not the gas as I can't afford to buy any more at the moment.
I will also have a go at upping the gas flow rate.
Well it appears that I've managed to fix it, but I dont have a clue how, I decided to give up trying to fix it and actually do some work with it and see if the welds are decent quality.
I am making a new workbench so needed to do quite a few fillet welds, so decided to start with them. With the gas flow setting set to 10l/min and the welder set to appropriate settings (I was welding 1.5 ERW to 3mm mild steel), and for some reason it just worked, no brown staining what so ever.
Different torch angle maybe? Thinking a bit more about your technique could have been all it was. Even if you feel you're not doing anything differently you may have changed something very slightly and cured it.
Well done anyway.
Fillet welds help to contain the gas shield, so you may still have a problem with butts and open corners, but as others have said now that you appear to have ruled out a machine fault, it must be down to torch angle / technique, or a draught disturbing the gas,