Which tungsten material is known for having the poorest heat resistance?

Pure tungsten is known for having the poorest heat resistance among the types of tungsten materials used in welding. This is primarily due to its lower alloying content and lack of added oxides or elements that enhance thermal stability and longevity under high-temperature conditions.

In welding applications, the addition of elements such as thorium or zirconium, as seen in thoriated and zirconiated tungstens, significantly improves heat resistance and electrode performance. Thoriated tungsten, for example, can withstand higher temperatures and provides better arc stability, making it suitable for a wide range of welding processes. Similarly, zirconiated tungsten offers good performance in AC welding due to its enhanced thermal and electrical properties.

Cerated tungsten, which includes a blend of cerium oxide, also provides superior heat resistance and is designed for specific welding applications requiring low heat input.

When considering heat resistance, pure tungsten does not offer the advantages associated with the alloyed tungsten variants, making it the least suitable choice in high-heat applications such as Gas Tungsten Arc Welding (GTAW).