Ferrite network
A ferrite network forms during slow cooling below the A3 temperature at austenite grain boundaries. It can reduce the toughness of the material.
Physical-Chemical Mechanism of Action
During slow cooling below the A3 temperature, proeutectoid ferrite continuously precipitates at the austenite grain boundaries. This process forms a network of ferrite that permeates the metal structure.
Metallurgical Relevance & Welding Risks
A ferrite network can reduce the toughness of the material and lead to increased susceptibility to cracking. It can also impair ductility, which can cause problems under mechanical loading.
Workshop Practice & Action Guidelines
To avoid a ferrite network, the weld should be cooled quickly. This can be achieved by a high cooling rate or by using cooling water. When selecting the welding process, ensure it provides the correct cooling rate to prevent a ferrite network.