Root opening
The air gap is the distance between the sheet edges that prevents achieving root fusion. An excessively large air gap can lead to uneven weld formation and porosity.
Physical-Chemical Mechanism of Action
The air gap is the space between the sheet edges where air does not come into direct contact with the molten metal. This prevents achieving root penetration because there is no direct contact between the hot metal and the air.
Metallurgical Relevance & Welding Risks
A too large air gap can cause the weld to cool unevenly. This can lead to porosity and a fine grain structure (fine grain), which affects the strength of the weld. Additionally, it can cause uneven weld formation, which reduces the mechanical properties of the joint.
Workshop Practice & Instructions
The air gap should be between 0.5 mm and 1 mm. This range ensures adequate cooling without porosity. For sheets thicker than 3 mm, the air gap can be increased up to 2 mm. Make sure the air gap is consistent and that no air pockets or stresses develop between the sheet edges.