Cap Pass
The cap layer is the top layer of a multi-pass weld that completely fills and protects the joint cross-section. It improves mechanical strength and prevents corrosion.
Physical-Chemical Mechanism of Action
The cap layer forms a dense layer that completely fills the joint cross-section. It consists of a strongly bonded metal lattice that forms through diffusion processes during welding.
Metallurgical Relevance & Risks in Welding
A missing or too thin cap layer can lead to corrosion and mechanical weak points. The weld becomes less strong and is susceptible to cracking and wear. Uneven deformation of the cap can also cause stress concentrations and additional hardness problems in the material.
Workshop Practice & Instructions
To achieve a good cap layer, the weld must be properly filled. This requires correct setting of welding parameters such as voltage amplitude and frequency. Using filler materials or special welding techniques can help create a dense and homogeneous cap. For metals with high corrosion risk, selecting the right protective layer material is crucial.