[cosi]

I have a question about gas selection. I have read here that 72/25 Ar C02 blend is what is readily available and best to use for mild steel. I have been reasearching and found this chart from one of the local suppliers link to gas mixture chart by SUPAGAS and it seems cleear that I should choose Supa Argon 52 but it goes against what I'm reading on weldingtipsandtricks.com Here is another local supplier and their weld gases welding gas by BOC and they also do all sorts of blends too but still unsure what to get for steel. I will mainly use this for thin plate up to 6mm and box/rectangular sections. Any help setting me straight would be appreciated.

[Braehill]

Cosi,
Here's a link to what I think is something everyone should read before they buy a tank of gas. Others have differing opinions, but he spells out his reasoning and has backed it up with real life cases. It's a lot to read, but hey, that's how we learn.

http://www.weldreality.com/

Len

[cosi]

wow, that is certianly a lot to read and I better get to it as I am heading to the store tomorrow to pick up the welder.

[xwrench]

I've been using straight CO2 for years with no complaints. Perhaps I just don't know what I'm missing. I may try a 75/25 mix next time just to form my own opinion, but as far as I can tell CO2 works fine.
Cheers.
-Eldon

[cosi]

THE BOTTOM LINE IS THERE IS NO NEED FOR ANY WELD SHOP TO USE THE 75 ARGON - 25% CO2 GAS MIX, AS THIS POPULAR GAS MIX HAS ALWAYS PROVIDED LESS THAN OPTIMUM WELD RESULTS FOR MOST OF THE COMMON MIG WELD APPLICATIONS.

That is a direct quote from the weldreality web site. It seems that the 75/25 mis is an 'all rounder'

This is also from the site;

____________________________________
Argon 10% CO2.
PULSED MIG Weldc
All steel and low alloy steels:

Compatible mix range. 8 to 12% CO2.

Applications: Best low energy MIG gas mix for spray and or "pulsed" carbon steel and low alloy steels welds on < 7 mm components. On many robot or manual carbon steel welded parts, the weld heat from high wire feed spray or pulsed welds can cause, distortion, weld burn through or excess weld fluidity causing weld undercut or oxidation. The fact that this gas provides lower energy than higher CO2 mixes makes it beneficial for these applications.

What is really interesting about this medium energy gas mix is that its also the best choice for welding thick steels as long as the?mill scale?and other surface contaminates are removed.

When spray transfer welding horizontal fillets larger than 6 mm, or multi-pass fillet welds in which the weld heat buildup is notable, the welder is aware of the high weld fluidity. Weld fluidity increases as the CO2 content of the gas increases. Argon with 15 or 20% CO2 produces welds with more fluidity than argon with 10% CO2. So if you want improved weld control remember this point.

With this same logic, if you are using the 10% CO2 mix with the pulsed / spray process on steels > 6 mm thick and you need more weld fusion , change the gas to a higher CO2 mix such as 15 - 20% CO2 mix.
______________________________________________________________________

I think I will be looking for this 90/10 mix when I get to the store tomorrow.
Still so much to read

[weldin mike 27]

Hey cob. We use Argoshield 51 for solid steel wire and Argoshield 52 for flux core. The boc website will have the make ups for those trade names and you can buy that mixture from any gas company.

[cosi]

Hey cob. We use Argoshield 51 for solid steel wire and Argoshield 52 for flux core. The boc website will have the make ups for those trade names and you can buy that mixture from any gas company.

It doesn't list Argoshield 51 but I am sure if I call them they will supply it. Great thanks for the advice.

Any other comments on the Supagas products?

[weldin mike 27]

Argoshield 51 Is sometimes called (or is called now, Argoshield universal) I don't no about supa gas except that they were very very dear in my town. How much welding fo you realistically see your self doing at home?

[Braehill]

Cosi,
If I remember right Argoshield (51)universal has about 2-3% oxygen added and about 18-20% CO2, balance Argon.

Len

[weldin mike 27]

We really don't get into mixture ratio's over here. They say use argon. Use argon. Mig gas Is Mig gas. Really follow the trade names, because, for many years, boc/cig was the only place to get gas.

[cosi]

I don't have a lot of welding to do now because I need to build my garage, plans went in to council the other day for approval.

At the moment I am just modifying my trailer, to add sides, to help with the demo works of the existing garage and get that rubbish to the tip. I am just welding 2mm box tube at the moment and I went for the monthly rental of the Argoshield Light. I was going to get the universal but that was for heavier gauge steel they said.

[weldin mike 27]

Consider these, I am going to buy one soon. this is for sale at Plumbtec I thing. Swap and go buy in for 170 then no rent. (this is argon)

[cosi]

So I have been practising with my new welder, I love it by the way, and I'm saw this pin hole and it happened twice in my practice beads. What does it mean?
Also the burning or black soot is that because there is too much or too little gas?

[weldin mike 27]

Pin holes like that are usually from surface contamination. The top plate has some nasty mill scale on it. (grind it off where possible) The blue primer is fine but just make sure it's fairly clean of dirt and oil. The sooty stuff comes from to low of a wire feed speed.