Best shielding gas mixture???? 2

[zimger]

We are robot welding mild steel with .045 wire, and having a great deal of trouble with porosity. Our gas flow is good, its not a drafty area, Plus checked our system for leaks. all seems to be good. The Japanese suggest using more CO2, will this help?

 

[metengr]

Porosity equates to either contaminants on the surface of the steel or wire or in the gas. Check to make sure that your steel surfaces and wire are clean prior to welding.

If these are ok, it has to be the shielding gas. Check the dew point of the gas and make sure that it is a welding grade with the proper dew point.

 

[vesselfab]

We use a 75/25 mix but like said...other contaminants.

are you using hard wire or flux cored wire

remember....too much gas flow can cause a venturi action and suck in contaminating air into your welding gas shield area

 

[dbooker630]

I have success with GMAW using a 85%Ar-15%Co2 mixture at 25psi. Surfaces are clean, free of paint or rust. You may need to go to a wire with increased manganese and silicon if you cannot effectively remove surface contaminants, perhaps ER70S-6 if you're using solid wire or an E70T-2 (100%Co2) if you use cored wire.

 

[unclesyd]

Here is some insight on welding gases by Ed Craig. The website is a little disjointed but there is some valuable information on it.

http://www.weldreality.com/MIG_welding_gases.htm

 

[GRoberts]

You can get porosity free welds with any Argon-CO2 mix clear to 100% Ar or 100% CO2. The gas mix ratio is not your problem. It is some sort of contamination, whether it be on or in the base metal, filler metal, or shielding gas. In my experience, porosity usually comes from base metal or wire surface contaminants or shielding gas flow problems.

 

[deanc]

What size gas cup are you using? Too much or too little flow.

Do you have any cooling water leaks?

Soap all your gas lines and fittings, may have a pin hole or thread leak.

Is your liner good?

Are you using Anti-spatter? To much is bad.

Any fans or vents in the area?

Leave a bowl of milk for the gremlins.