What type of filler metals are unacceptable for performing GTAW welds when derived from oxyfuel welding?

In the context of Gas Tungsten Arc Welding (GTAW), certain filler metals are deemed unacceptable based on their compatibility with the process and the materials being welded. Copper-coated mild steel is one such filler metal that should not be used for GTAW welds.

The primary reason for this is that the coating can negatively affect the integrity of the weld. The copper coating can introduce contamination during the welding process, leading to issues such as poor arc stability, excessive spatter, and incomplete fusion. Additionally, the heat generated in GTAW may cause the copper to melt and migrate into the base metal, resulting in difficulties in achieving desired mechanical properties and corrosion resistance.

In contrast, stainless steel, aluminum, and mild steel are often used as fillers in GTAW, as they are compatible with the process and can yield high-quality welds when handled properly. Thus, the choice of filler metals is crucial in achieving the best results in GTAW welding applications.