Discontinuous Precipitation
Discontinuous precipitation is a transformation process where lamellar precipitates form at grain boundaries, and the boundaries shift locally. This leads to the formation of zones with different mechanical properties.
Physical-Chemical Mechanism of Action
During discontinuous precipitation (DP), lamellar precipitates form at grain boundaries. The grain boundaries migrate locally, leading to zone formation with different mechanical properties such as hardness and ductility.
Metallurgical Relevance & Welding Risks
DP can lead to increased hardness and reduced ductility in the weld area, which can cause cracks and stress buildup. This is especially dangerous in stiff steels or under high loads.
Workshop Practice & Action Guidelines
To minimize the risks of DP, the weld area should be cooled as quickly as possible (t8/5 < 5 s). This prevents the formation of lamellar precipitates and maintains a homogeneous hardness structure. For stiff steels, it is important to continuously monitor the melting process and regulate cooling.