Which purge gas is commonly used during brazing?

Nitrogen is commonly used as a purge gas during brazing because it serves several important functions. When brazing, it is essential to prevent oxidation of the base metal and the filler material. Nitrogen purges out the air in the brazing area, effectively limiting the presence of oxygen that could lead to unwanted oxidation and contamination during the heating and cooling processes.

Additionally, nitrogen is inert, meaning it does not chemically react with the metal being brazed or the brazing filler material. This inertness helps ensure a clean joint, which is critical for the structural integrity and overall performance of the braze joint. By displacing air and creating a non-reactive atmosphere, nitrogen supports the formation of high-quality braze joints that are strong and reliable.

Using other gases like oxygen or propane may contribute to oxidation or combustion, which can compromise the quality of the brazing process. Therefore, nitrogen is the preferred choice for purging when brazing different materials.