How to get Better Welding Result by using CO2 instead of Argon gas

I am not an expert on welding but in my experience using Argon with CO2 will give you better,neater and stronger welds.If you are as you say in the Automotive components fabrication field I think you should not cut this particular corner!!!.

Generally speaking CO2 is a ferrous shield gas as apposed to argon a non ferrous shield gas. I have seen many unsatisfactory welds using the inappropriate shield gas. Please ask your customer to substantiate his or her dire request for such.

I consistantly use 75/25 profitably. What are they asking you to weld? You can cut your expense by negotiating with differnt suppliers, I have cut my cost by over 20% by playing them against each other. Watch your gas flow and don't over weld. I can't believe you can't weld profitably with argon mix. You might also submit a weld sample to an independant inspector if you are convinced you have satisfactory welds. The cost for a destructive test might be worth it.

possien is correct. We have also used 75/25 with great success. If the custmer requires 85/18 then you will probably need to go with that. However work your suppliers to get the lowest price you can. We have gotten ours down by 30%. If it can be done in upstate NY it can be done anywhere

sorry that was supposed to read 85/15 not enough coffee yet

When you weld with a TIG or MIG torch the shielding gas flows out of the torch, mixes with the environment, and is lost. Depending on several factors, including the size of the parts you are welding, you may be able to weld in a sealed chamber where the shielding gas is not lost. If properly managed, this arrangement can save a lot of gas.

The gas type affects the deposition mode of MIG welding. In the spray-arc transfer mode (higher voltages and currents) Argon produces a fine metal spray and neat welds with a high deposition rate. Pure CO2 produces a coarse molten droplet and the transfer of metal is called "short circuit" or "globular" tranfer. It is not so neat or good looking and the deposition rate is low. A mix of Ar and CO2 is a good compromise. If you must use pure CO2 then you must have a welding power supply with adjustable slope, voltage, and inductance characteristics to accomodate for the globular transfer and to optimize it. In the long run the Ar-CO2 mix is probably the most cost effective method.

Like to add to further to what was said by other members.

Since you have not mentioned type of transfer, wire size and shielding gas flow rate, thickness of the sheet ( being a auto component) I assume it could be with 0.80 / 1.20 mm size wire using globular transfer which is commonly used for automatic welding . if it is semi auto it could be dip / short circuit (or) globular/ semi automatic.

In globular transfer, ( above 23 volts) use of CO₂ gas will produce both axial and non axial ( which forms spatter) In short circuiting transfer, Co₂ helps to give better penetration for medium thickness (and above) metals. It is economical, provides axial flow good for, dip & globular modes and for carbon steels.

The draw back with CO₂ gas is that the arc will be harsh, provides convex bead, produces lot of spatter , (being a reactive gas) and requires lot of post welding efforts to remove them . A waste of man-power and increase in overheads. Further spatter clogs the nozzle and may requires frequent cleaning.

Carbon dioxide is unsuitable for positional welding ( Argon is three times heavier than air) other than down hand (flat) and will not provide aesthetic look for the bead. But a mixture of CO₂ with Argon ( 75 to 80 % ) produces less harsh arc, and a flatter_, more fluid and desirable weld profile, more wet-ability at side fusion zone hence preferred although it is costlier in auto mobile industries.

Hence it has become a accepted practice off late to use Argon + CO2 mixture in place of pure Aragon and pure CO₂ gas both for CS and SS metals in Auto industries.

Sridhar - Welding Training Institue - Chennai-India.