Self-shielded wire with gas?

Farmwelding · Mon Feb 20, 2017 8:31 pm

Has anybody tried running self shielded wire with gas. I was thinking how it would be interesting to see how it ran but as of right now my school lacks gas and I don't want to keep switching hoses and moving a 70 pound machine. Seems like it wouldn't be great, but curiosity has gotten the better of me.

Coldman · Mon Feb 20, 2017 8:52 pm

Some of the purposes of flux are:
-protect the weld pool from atmospheric contamination
-slow the cooling rate of the heat affected zone
-add alloying ingredients to the weld pool

Adding gas would still protect from atmospheric contamination, ok but doubling up does not make it better I think.
Adding gas shield means velocity over the weld pool therefore the cooling rate speeds up having two possible effects:
grain growth due to rapid cooling
faster solidification of slag and maybe less deposition of alloying ingredients.

The result is therefore unpredictable and probably undesirable. Always better to stick with manufacturer's instructions.

When are you going to start posting up some of your work?

Farmwelding · Mon Feb 20, 2017 9:17 pm

Maybe once we get gas I'll hook it up and found out what it looks like and see if I can do some macro etching(unlikely but I'll see what I can do). Usually I don't have time to take pictures of my welds or don't think about it. In usually busy trying to teach some other guy what to do. Ill try to do more pictures.

MinnesotaDave · Mon Feb 20, 2017 9:22 pm

Lincoln says no - here is their answer to the same question:

A: The answer to your first question is no. Not only is the use of any type of shielding gas not necessary for Innershield® NR-212, or any other type of self-shielded, flux-cored electrode (FCAW-S), it should not be used. FCAW-S (i.e. Innershield®) electrodes have a tightly controlled and unique core composition and interaction with the atmosphere (compared to gas-shielded, flux-cored wires). They rely on the oxidizing effect of air to produce the desired weld deposit and desired resulting mechanical properties. When you use a shielding gas, you block the arc from the air and prevent the oxidizing reactions. This results in a much higher level of alloys, such as aluminum, in the weld metal, which produces a brittle and crack sensitive weld deposit. While it is likely that the shielding gas improves the stability and operator appeal of NR-212, it also results in an unacceptable weld deposit.

Farmwelding · Mon Feb 20, 2017 11:25 pm

Thank you Dave. That was very helpful. Makes me want to test a t-joint with both ways and do a little crude sledge break test. It'll be interesting. Keep you all posted. Nothing I would do for anything structural but just curious to see what the slag looks like and spatter and what not.

MinnesotaDave · Tue Feb 21, 2017 12:06 am

Farmwelding wrote:Thank you Dave. That was very helpful. Makes me want to test a t-joint with both ways and do a little crude sledge break test. It'll be interesting. Keep you all posted. Nothing I would do for anything structural but just curious to see what the slag looks like and spatter and what not.

Just out of curiosity, why would you waste your time with that?

Farmwelding · Tue Feb 21, 2017 12:11 am

MinnesotaDave wrote:
Farmwelding wrote:Thank you Dave. That was very helpful. Makes me want to test a t-joint with both ways and do a little crude sledge break test. It'll be interesting. Keep you all posted. Nothing I would do for anything structural but just curious to see what the slag looks like and spatter and what not.
Just out of curiosity, why would you waste your time with that?

1. Practice t-joint with flux core at least without the gas 2.learn about weld components (what welds look like when the y fail or have issues within the weld since I haven't done a lot of destructive testing) 3. Have the information here so if somebody else has the same thought they can look here and see as a resource to check themselves. 4. Keeps me in the booth