Which type of filler rod must be used in GTAW?

In Gas Tungsten Arc Welding (GTAW), it is essential to use a filler rod that matches the material and alloy being welded to ensure compatibility and a strong bond between the base materials. The properties of the filler rod must align closely with those of the base metal in terms of chemical composition and mechanical properties. This compatibility helps avoid issues such as cracking, inadequate fusion, or undesirable changes in the material characteristics as the weld cools and solidifies.

Using a filler rod that does not match the base material can lead to problems like corrosion or reduced strength in the weld joint. It is particularly important when working with specialized materials or alloys, where specific filler metals are required to achieve the desired performance and characteristics.

In contrast, factors such as the diameter of the filler rod or its compatibility with the welding machine are secondary considerations in GTAW once the material-match aspect is addressed. The focus must remain on the chemical and physical compatibility to achieve optimal results in the welding process.