Local root undercut

Physical-Chemical Mechanism of Action

Local incomplete root fusion occurs due to uneven melt distribution or too rapid cooling, leading to the formation of a sharp-edged kink effect. This kink can serve as a starting point for fatigue fractures.

Metallurgical Relevance & Welding Risks

Local incomplete root fusion increases stress concentration at the weld transition, which can lead to fatigue fractures. This can be particularly dangerous with stiff steels or under high mechanical loads.

Workshop Practice & Action Guidelines

To avoid local incomplete root fusion, ensure even melt distribution and control the cooling steps. Use appropriate welding parameters such as a sufficiently long hold time in the molten pool (t8/5) and controlled cooling.