Precipitation Hardening
Aushaerten is the process where oxygen or other elements are precipitated from a supersaturated base matrix to increase strength. This happens through targeted precipitation in the weld pool.
Physical-Chemical Mechanism of Action
Aushaerten occurs through the precipitation of oxygen or other elements from the supersaturated base matrix of the steel. This happens when the melting temperature drops below the critical point temperature and the chemical equilibrium reactions take place.
Metallurgical Relevance & Risks in Welding
Aushaerten can lead to increased strength but also improves toughness. Incorrect precipitation hardening conditions can lead to hot cracks or glass-hard microstructures, making the material more brittle.
Workshop Practice & Instructions
To ensure proper precipitation hardening, the melting temperature must be maintained precisely. For steels with high oxygen content, controlled cooling is essential. The cooling rate should be chosen such that the microstructure does not become too glass-hard (t8/5 between 10 and 20 seconds).