Root pass sequencing

The process-technical specification of the initial pass in thick-walled butt or fillet welds to prevent hot cracking in the highly stressed root zone. It defines current intensity, restraint, and cooling rate.

Lay the root pass first and carefully. It is the foundation of the weld and must be fully fused without burning the material. You want to prevent the weld root from cooling too quickly and becoming hard and brittle. Adjust the heat input so that the root pass fuses cleanly, but the grain structure is not coarsened. If you work too hot or too fast here, you'll get cracks or a brittle weld.

MetallurgieSchweißtechnik