Q: I have a small MIG welder that I sometimes use to weld with 0.045-in. Innershield^® NR-212 wire. I know it is a gasless wire. However, is it okay to use shielding gas (e.g. 75% Ar / 25% CO₂) with it? I tried it once on some scrap plate and it seemed to work pretty well. I also noticed the AWS number for the wire, E71TG-G, has the “G” in it. Does that mean it is okay to use with gas?

Shielding gas is not necessary for FCAW-S wire, and should not be used because it will block the arc from the air and prevent oxidization.

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.

Regarding the American Welding Society (AWS) classification of Innershield^® NR-212 (E71TG-G): I can see where that would lead to some confusion. While the "G" in FCAW-G stands for gas-shielded (or the “S” in FCAW-S, for self-shielded), the "G" in a specific electrode AWS classification stands for “general.” Therefore, an E71TG-G classification does not mean that it is a gas-shielded electrode. Typically, a U.S. welding electrode manufacturer (such as Lincoln Electric, etc.) designs an electrode to meet the requirements of a specific, predefined AWS electrode classification, per the appropriate AWS Filler Metal Specification (such as E71T-1, E71T-8, E7018, ER70S-6, etc.) However, a manufacturer is still free to make a particular electrode that does not meet any predefined AWS classification. In these cases, it is classified as "general".

In the specific instance of Innershield^® NR-212, the first "G" in the electrode’s AWS number means it has a general usability classification. Innershield^® NR-212 also happens to be a low-alloy electrode (i.e., under AWS A5.29 Filler Metal Specification). These electrodes have alloy designations in their suffix (i.e., E71T8-K6, E81T1-K2, E81T1-Ni1, etc.). In the case of Innershield^® NR-212, the second “G” is a general alloy suffix classification. Therefore, E71TG-G is its classification.

Tom Myers is a Senior Application Engineer for The Lincoln Electric Company. As a member of the Application Engineering Department, he specializes in flux-cored and stick welding processes. He has over 22 years of welding experience with Lincoln Electric, including 10 years as a Technical Sales Representative, eight years in the Technical Training Department, with concurrent positions as the Corporate Sales Training Manager and Educational Services Manager. In these roles, he was responsible for training of Lincoln Electric’s technical sales force, as well as many customer and distributor training programs. In addition, he was the coordinator for Lincoln’s educational programs and services available to public and private welding schools.

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