Peritectic solidification
Peritectic solidification: During cooling, a liquid and a solid phase react to form a new solid phase. This is often diffusion-controlled and shapes the microstructure of medium-carbon steels.
Physical-Chemical Mechanism of Action
During peritectic solidification, a liquid phase and an existing solid phase react under diffusion conditions during cooling. This leads to the formation of a new, different solid phase. The process is often slow and controlled.
Metallurgical Relevance & Welding Risks
Peritectic solidification can result in complex microstructures that impair mechanical properties. Too rapid cooling can prevent the desired microstructure from fully developing, leading to toughness and hardness issues. Too slow cooling can cause grain coarsening and thus a reduced strength level of the weld.
Shop Practice & Action Guidelines
To successfully perform peritectic solidification, controlled cooling is required. This can be achieved by choosing the right welding process and the correct cooling time. For medium-carbon steels, the cooling time should be set so that the microstructure develops optimally. Too rapid cooling can be avoided by slow cooling in an oven or by using cooling water.