CCT diagram
The CCT diagram shows how the structure of a metal changes during continuous cooling. It helps understand phase transformations and select the right welding process.
Physical-Chemical Mechanism of Action
The CCT diagram (time-temperature-transformation) shows how the microstructure of a metal changes during continuous cooling. It visualizes the phase transitions and the development of the grain size ratio.
Metallurgical Relevance & Risks in Welding
The CCT diagram is crucial for understanding microstructure development at different cooling rates. Too fast or too slow cooling can lead to undesirable microstructures, such as glass-hard martensite or excessively large grain size, which impairs the toughness and formability of the material.
Workshop Practice & Action Guidelines
To achieve the right microstructure, welding technicians must precisely control the cooling process. This can be done by choosing the appropriate welding process and parameters. For example, in steels: fast cooling (short time span) can lead to a hard microstructure, while slow cooling results in a soft, more formable structure.