Peritectic reaction

Peritectic is a reaction during cooling where a solid phase and the remaining melt together form a new solid phase. This happens in certain alloys when the melt can no longer absorb everything. In welding, this can lead to hard, crack-sensitive microstructures, especially when the carbon content is high. To avoid problems, let the part cool slowly and in a controlled manner. For critical steels, a post-weld heat treatment helps to reduce hardness and prevent cracking.