Which types of curves are used to construct TTT diagrams?
Explanation: S curve, C curve isothermal diagram and Bain’s curve are all names given to time temperature transformation diagrams.
Why is TTT curve C shaped?
Transformation of austenite is plotted against temperature vs time on a logarithm scale to obtain the TTT diagram. The shape of diagram looks like either S or like C. temperature due to low driving force or nucleation rate. At higher under coolings or lower temperature finer pearlite forms.
Why TTT diagram is called S curve?
Time-Temperature-Transformation (TTT) diagram or S-curve refers to only one steel of a particular composition at a time, which applies to all carbon steels. This diagram is also called as C-curve isothermal (decomposition of austenite) diagram and Bain’s curve. Austenite is stable above eutectoid temperature 727 °C.
What does the TTT curve show?
Isothermal transformation diagrams (also known as time-temperature-transformation (TTT) diagrams) are plots of temperature versus time (usually on a logarithmic scale). Time-temperature-precipitation diagrams and time-temperature-embrittlement diagrams have also been used to represent kinetic changes in steels.
What is the TTT diagram for iron carbide?
TTT diagram indicates a specific transformation starts and ends and it also shows what percentage of transformation of austenite at a particular temperature is achieved. The Iron–Iron Carbide (Fe–Fe3C) Phase Diagram In their simplest form, steels are alloys of Iron (Fe) and Carbon (C).
How are TTT plots and CCT diagrams used?
This section looks at Phase Diagrams, TTT plots and CCT diagrams. These are important in predicting what alloying components will be present in the affected steel, through different cooling rates. The iron-iron carbide phase diagram is shown to the left.
Where do the lines merge on a TTT curve?
These two lines generally merge at the nose region. Figure given below, TimeTemperatureTransformation (TTT) curve for carbon steel AISI 1050 (a hypoeutectoid steel) will help understanding what is meant by additional line above the nose region. The horizontal M s line shows the temperature at which martensite transformation will start.
What does time temperature transformation ( TTT ) diagram mean?
Time-Temperature-Transformation (TTT) Curves TTT diagram is a plot of temperature versus the logarithm of time for a steel alloy of definite composition. TTT diagram indicates a specific transformation starts and ends and it also shows what percentage of transformation of austenite at a particular temperature is achieved.
