What AWS classification is used to weld carbon steel in the context of GTAW?

The classification used to weld carbon steel in the context of Gas Tungsten Arc Welding (GTAW) is ER70S-X. This filler metal is specifically designed for use with carbon steel and has a composition that allows it to effectively weld materials such as mild steel and certain low alloy steels.

The "ER" designation indicates that the material is an electrode rod that can be used for welding. The "70" denotes the minimum tensile strength of the weld metal, which is 70,000 psi, making it suitable for many structural applications. The "S" signifies that it is a solid wire, and the "X" allows for certain variations in alloying elements that may be contained in the filler.

Selecting the appropriate filler metal is crucial for ensuring strong, durable welds that will meet the required mechanical properties of the final joint. In contrast, other classifications such as ER4043, ER308, and ER5356 are intended for welding aluminum and stainless steel, respectively, and are not suitable for carbon steel applications in GTAW.