Continuous cooling transformation

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Continuous cooling transformation diagram of EN S355 (ASTM A-572 Grade 50, warranted yield stress 355 MPa) for welding (fast cooling, linear scale).

A continuous cooling transformation (CCT) phase diagram is often used when heat treating steel.[1] These diagrams are used to represent which types of phase changes will occur in a material as it is cooled at different rates. These diagrams are often more useful than time-temperature-transformation diagrams because it is more convenient to cool materials at a certain rate than to cool quickly and hold at a certain temperature.

Types of Continuous Cooling Diagrams[edit]

There are two types of continuous cooling diagrams drawn for practical purposes

  • Type 1: This is the plot of transformation start, a specific transformation fraction and transformation finish temperature for all products against transformation time on each cooling curve.
  • Type 2: This is the plot of transformation start, a specific transformation fraction and transformation finish temperature for all products against cooling rate or bar diameter of the specimen for each type of cooling medium.


References[edit]

  1. ^ Transformation diagrams (CCT & TTT), retrieved 2008-04-17 .

See also[edit]