Root face
Root face height is the unmachined vertical area at the bottom edge of the joint that prevents the weld pool from falling through during the first pass.
Physicochemical Mechanism of Action
The land height forms a barrier that holds the weld pool during the first pass. It prevents the weld pool from falling through uncontrollably and causing uneven weld bead formation.
Metallurgical Relevance & Risks in Welding
A land that is too low can cause the weld pool to flow away too early. This can lead to incomplete weld fill and cracks or breakage in the joint. On the other hand, a land that is too high increases the risk of porosity and can slow down the weld pool excessively, leading to long weld times and potential distortion.
Workshop Practice & Instructions
The land height should be between 2 and 4 mm. For steels with high carbon content (e.g., HSS), the land height can be slightly higher to ensure adequate weld fill. Make sure the land is straight and free of irregularities to ensure even melting.