Globular Precipitation
Globular precipitates form round, fine particles within the steel, increasing mechanical resistance and blocking dislocation movement.
Physical-Chemical Mechanism
Globular precipitates are formed by the targeted formation of round particles within the metallic matrix. These particles can consist of various materials such as silicon or nickel and serve to block dislocation movement in the crystal structure.
Metallurgical Relevance & Welding Risks
Globular precipitates increase the hardness of the steel and improve its mechanical properties. However, an uncontrolled precipitation process can lead to hardening of the weld, which can cause hot cracking and reduced toughness. It is important to control precipitation to ensure an optimal weld.
Workshop Practice & Action Guidelines
To successfully incorporate globular precipitates, the content of the precipitating element in the weld pool must be precisely controlled. For steels with silicon precipitation, the optimal content is typically between 0.1% and 0.3%. The weld should be cooled slowly (t8/5 > 25 s) to ensure uniform precipitation. If cooling is too fast, precipitation can be irregular and lead to hardening.