Preheat Temperature Calculator

Preheating slows the cooling of the weld. This reduces hard, brittle microstructure regions in the heat-affected zone, lowers residual stresses and gives hydrogen time to escape. This primarily reduces the risk of cold cracks.

capilla supports you in finding the right preheating strategy for your material and component.

If cooling is too rapid, martensite can form – a hard, brittle microstructure. In combination with residual stresses and hydrogen, this promotes cold cracks, which sometimes appear only hours after welding and jeopardise the joint.

capilla advises you on material and filler material to prevent such defects from the outset.

The decisive factors are the chemical composition of the base material expressed via the carbon equivalent, the component thickness, the hydrogen content of the weld metal and the heat input applied. Only the interaction of these variables yields the correct temperature.

capilla helps you correctly assess these factors and translate them into safe welding practice.

The carbon equivalent summarises the influence of carbon and additional alloying elements on the hardenability of the steel in a single characteristic value. The higher it is, the more the material tends to harden and the higher the preheating generally needs to be.

capilla supports you in material assessment and in selecting the appropriate filler material.

Thicker components conduct heat away from the weld area faster and therefore cool more rapidly. As wall thickness increases, the required preheat temperature generally also rises.

capilla has the experience to weld safely even thick-walled and demanding components.

Yes. For multi-pass welds, the preheat temperature should be maintained as the interpass temperature. If the component drops too far between passes, protection against excessively rapid cooling is lost.

capilla accompanies you with specialist expertise throughout the entire welding process, from the first to the last pass.

The tool is designed for unalloyed, low-alloy and higher-strength steels where cold cracking risk exists. Different rules may apply to other material groups – when in doubt, the material data sheet and relevant standard should be consulted.

capilla offers suitable filler material and the necessary consulting for virtually every material group.

No. The tool provides a reliable reference value for the preheat temperature. For components subject to standards requirements, the preheat temperature remains part of a qualified welding procedure specification (WPS) and should be documented there.

capilla supports you with welding engineering expertise in the standards-compliant implementation of your projects.