Discontinuous Precipitation
Discontinuous precipitation is a reaction type where supersaturated solid solutions transform at grain boundaries into lamellar structures with a matrix-depleted phase and precipitates. This leads to local property changes.
Physical-Chemical Mechanism of Action
During discontinuous precipitation, supersaturated solid solution phases react at grain boundaries with a matrix-depleted phase. Precipitates form in lamellar structures, altering the local composition and properties of the material.
Metallurgical Relevance & Welding Risks
These processes can lead to local hardness variations and cracks. Too-hard precipitates can contaminate the structure and impair the toughness of the material. Local property changes can also lead to hot cracking or weld failure.
Workshop Practice & Action Guidelines
To minimize discontinuous precipitation, it is important to carefully control melting time and temperature, as well as cooling duration. Use suitable protective agents and avoid critical cooling rates. For special materials, additional tests should be performed to determine optimal process settings.