Gas shielding efficiency
Shielding gas effectiveness describes how well the weld metal absorbs and protects against reactive environmental components. This prevents porosity and embrittlement.
Physicochemical Mechanism of Action
Gas shielding effectiveness refers to the ability of weld metal to bind and intercept reactive components of the surrounding air, such as oxygen or nitrogen. This prevents these gases from penetrating into the weld pool and acting as reactivity agents.
Metallurgical Relevance & Welding Risks
Low gas shielding effectiveness leads to porosity and embrittlement of the weld seam. Pores form when oxygen enters the weld pool and reacts with carbon, forming carbon gas that becomes gas bubbles in the weld seam. Embrittlement occurs when the weld metal cools too quickly and loses insufficiently bound oxygen, resulting in crack-prone microstructures.
Workshop Practice & Action Instructions
To ensure good gas shielding effectiveness, use weld metal with a high content of silicon or titanium. These elements effectively bind oxygen. Make sure the weld metal is dry and clean before use. Also, maintain a stable weld pool and keep the temperature constant. For highly reactive materials like austenite, increase gas shielding effectiveness through a longer pre-treatment in an inert gas environment.