CCT diagram usage for controlled cooling

[Closius]

Continuous cooling transformation (CCT) diagram is used for representing which types of phase changes will occur in a material as it is cooled at different rates. This diagram is built by natural cooling of alloy.

Is it possible (correct) to use a CCT diagram for controlled cooling (variable history of temperature)? If yes, could you tell me how to use it or where can I find some information of how to use it in such way?

For example, blue and green lines are CCT curves. The red line is the history of controlled cooling for one point in the sample. Can I get the point A (a phase composition) using red curve?

Best regards,
Anton.

 

[metengr]

This diagram is built by natural cooling of alloy.

No. The CCT diagram normally contains various cooling rates (from air to rapid cooling) and subsequent phases which develop from the stated cooling rate. Some diagrams even provide hardness based on a specific cooling rate.

 

[Closius]

The CCT diagram normally contains various cooling rates (from air to rapid cooling)

I mean this is an isokinetic curve of cooling. It is a natural cooling. But controlled cooling has variable velocity of temperature changing.

 

[metengr]

Regardless of terminology differences, you can still use a CCT to predict phases that will form projecting through start and stop transformation boundaries with a variable velocity cooling rate or otherwise.

 

[EdStainless]

CCTs are developed using dozens of cooling rates, arrest temperatures, and hundreds of samples.
Yes, you can engineer a cooling scheme that will let you land in a particular phase field and begin the transformation.
But CCT does not contain information about the time transformations take to finish.
There are many commercial processes built on interrupted quench and controlled phase transformation, things like patenting and austempering come to mind.

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P.E. Metallurgy, Plymouth Tube