Spheroidized Carbides
Globulized carbides are spherical carbon precipitates in a ferrite matrix, formed by annealing treatments. They improve the cold formability and toughness of the steel.
Physical-Chemical Mechanism of Action
Globulized carbides form when ferrite is slowly cooled in a protective environment (such as during annealing treatments). Carbon precipitates form into small spherical particles distributed in the ferrite matrix.
Metallurgical Relevance & Welding Risks
This structure improves the cold formability and toughness of the steel because the small carbide particles stabilize the structure. However, excessive carbon content can lead to increased hardness, which can cause cracks and wear problems during welding. It is important to control the carbon content.
Workshop Practice & Action Instructions
To create globulized carbides, the steel is slowly cooled in a protective environment (often under a shielding gas atmosphere). The cooling time should be between 10 and 30 minutes, depending on the steel thickness. Too fast cooling can lead to martensite formation, while too slow cooling results in increased hardness and reduced formability.