schutzgas

Schutzgas, or shielding gas, is a non-consumable gas used during welding to shield the weld pool and surrounding metal from atmospheric gases such as oxygen, nitrogen, and water vapor. The protective atmosphere prevents oxidation, porosity, and other weld defects, helping to maintain mechanical properties and appearance. Shielding gas is delivered through a gas nozzle around the arc and filler metal, with the composition and flow rate chosen according to the process, material, and joint design.

Common shielding gases include inert gases such as argon and helium, as well as active gases such as carbon dioxide. Mixtures are widely used: argon with small amounts of CO2 or oxygen for steel MIG/MAG welding; argon with helium for nonferrous metals; and pure argon or argon with trace amounts of hydrogen or nitrogen for certain alloys in TIG welding. Carbon dioxide alone is a cost-effective option for MAG welding of steel, though it can increase spatter. Helium provides higher heat input for thick materials or specific alloys. Typical flow rates range from roughly 6 to 20 liters per minute, adjusted for joint design, welding position, and ventilation.

In practice, shielding gas is supplied from cylinders with regulators and connected to the welding torch or nozzle. The choice of gas or gas mixture affects weld stability, penetration, spatter, and arc characteristics. Safety considerations include proper cylinder securing, adequate ventilation, and attention to gas purity and storage conditions.