Welding Continuous Cooling Transformation Diagram
The continuous cooling transformation diagram shows how austenite transforms into various microstructures depending on the cooling rate. It helps predict the microstructure and mechanical properties of the weld.
Physicochemical Mechanism of Action
The Continuous Cooling Transformation (CCT) diagram visualizes the phase transformations of austenite into ferrite, pearlite, bainite, or martensite. Depending on the rate and temperature, the metal develops differently.
Metallurgical Relevance & Welding Risks
Incorrect cooling rates can lead to undesirable microstructures that cause finer cracks or reduced toughness. For example, too rapid cooling can produce glass-hard martensite, which is prone to cracking.
Workshop Practice & Action Instructions
Use the CCT diagram to determine the optimal cooling rate. For steels with high carbon content (e.g., HSS), choose slow cooling (t8/5 > 25 s) to produce bainite or pearlite. For general steels, a medium cooling rate (t8/5 between 5 and 25 s) is suitable.