Trailing shield
The trailing shield is an extra gas nozzle used in welding that follows the torch and keeps shielding gas over the still-hot, solidified metal. It prevents harmful oxidation of reactive metals like titanium.
Physical-Chemical Mechanism
The trailing shield sprays shielding gas over the weld zone right after the metal has solidified. This prevents the hot metal from contacting the air and oxidizing.
Metallurgical Relevance & Welding Risks
Without a trailing shield, the solidified metal can quickly oxidize on the surface, leading to a poor weld. Oxidation can also impair the strength and toughness of the material.
Workshop Practice & Procedures
Use a trailing shield when welding reactive metals like titanium or aluminum. Make sure the shield is positioned right behind the torch and provides a constant gas flow. The optimal distance between torch and trailing shield is about 10 cm.