What is the Difference Between Iron Carbon Diagram and TTT Diagram?

The iron-carbon diagram and the TTT (Time-Temperature-Transformation) diagram are both important phase diagrams, but they differ in the conditions under which they are drawn and their applications.

Iron-Carbon Diagram:

• Represents the phase relationships in iron-carbon alloys.
• Plots temperature against carbon composition.
• Indicates the phases present and the phase changes that occur during heating and cooling.
• Represents equilibrium conditions.

TTT Diagram:

• Represents the time-temperature-transformation relationships in steel alloys.
• Plots temperature against the logarithm of time.
• Indicates specific transformations that start and end, as well as the microstructures corresponding to those transformations.
• Represents non-equilibrium conditions.

In summary, the key difference between the iron-carbon diagram and the TTT diagram is that the iron-carbon diagram uses equilibrium conditions, while the TTT diagram uses non-equilibrium conditions to draw the phase diagram. The iron-carbon diagram is useful for understanding the different phases of steel and the phase changes that occur during heating and cooling, while the TTT diagram is extensively used to study phase changes and their corresponding microstructures in situations where non-equilibrium conditions exist.

Comparative Table: Iron Carbon Diagram vs TTT Diagram

The iron-carbon diagram and the TTT (Time-Temperature-Transformation) diagram are both phase diagrams used to understand the behavior of steel and its microstructure. Here is a table summarizing the key differences between the two diagrams:

• The iron-carbon diagram uses equilibrium conditions and shows the different phases of steel and cast iron, with temperature plotted against carbon composition.
• The TTT diagram, on the other hand, uses non-equilibrium conditions and shows the time-dependent phase transformations, with temperature plotted against time.

In summary, the iron-carbon diagram is useful for understanding the different phases of steel and its microstructure, while the TTT diagram is useful for heat treatment and understanding the kinetics of phase transformations.