Hello Jer, the best way to explain why manufacturers specify certain gases for use with certain wires has to do with the metallurgical makeup of the deposited weld metal. Even though you can't see a difference or you don't notice a difference when you are making the weld, chances are if samples were sent to a lab and analyzed there would be a difference in the deposited weld metal. If destructive testing were employed on the weld samples you might also notice differences in tensile capabilities and other metallurgical characteristics. Cracking in or around the weld zone can sometimes be a problem or underbead cracking can be present which you can't see. It was once explained to me that additional amounts of argon present in shielding gas mixes other than that specified would not allow certain percentages of alloying materials in the fluxes to be burned out in the welding arc during the welding process and thus the deposited metal could be subject to cracking because of elevated levels of these materials. Hope this helps to shed a bit of light on your question. Regards, aevald

In addition to earlier comments, you probably will not see a dramatic difference in the weldability or bead appearance in a flux cored stainless wire as long as you still have 10% or more argon in the gas. If you want to see the "difference" switch to 100% CO2.

Most SS FCAW wires now are designed to meet the chemistry and mechanical properties of A5.22 using either gas (and are dual classified as -1/-4) but the argon addition definitely gives a smoother arc and bead appearance.

Using stainless steel flux core wire, it is advisable to use either straight CO2, or a mixture of argon with at least 20-25% CO2 for the -1 and -4 designated electrodes. The 20-25% CO2 reacts with the oxidizing agents to give better slag removal, better weld bead appearance and less spatter, just to name a few. Although ANSI/AWS A5.22-95 specifically states that "the requirement for the use of specified external shielding shall not be construed to restrict the use of any other medium for which the electrodes are found suitable, for any application other than the classification tests." In other words, the only gas combinations used to test FCAW at the test facility is straight CO2 and 75-80% Argon/remainder CO2.

Chuck

I'd like to thank all of you for your responses. I did use the C-25 for the weldments, and thanks again for the in depth info.

Jerry