Show isothermal transformations (constant temperature) over time.
Used to study bainite, pearlite, and martensite formation.
π Key Features of TTT Diagrams:
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Nose of the curve (~500Β°Cβ600Β°C): Fastest pearlite formation.
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Upper Bainite (~400Β°Cβ500Β°C): Coarser structure, moderate hardness.
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Lower Bainite (~250Β°Cβ400Β°C): Finer structure, higher toughness.
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Ms (Martensite Start) & Mf (Martensite Finish) Lines: Show when martensite forms during quenching.
Show transformations during continuous cooling rather than at constant temperature.
Useful for practical heat treatment processes.
π Key Features of CCT Diagrams:
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Slow Cooling β Pearlite Formation (Ductile but lower strength)
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Moderate Cooling β Bainite Formation (Strong and tough)
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Rapid Cooling β Martensite Formation (Hard and brittle)
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Optimize Heat Treatment (Quenching, tempering, annealing, normalizing)
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Predict Microstructure Changes (Pearlite, bainite, martensite formation)
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Improve Mechanical Properties (Strength, hardness, toughness)
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Prevent Unwanted Transformations (Avoid cracking in welding and casting)
πΉ Automotive & Aerospace: Controlling hardness and toughness in gears, crankshafts, and turbine blades.
πΉ Tool & Die Manufacturing: Producing martensitic steels for cutting tools.
πΉ Structural Engineering: Ensuring ductile yet strong steel for bridges and buildings.
πΉ Welding: Preventing cracks and distortions by controlling cooling rates.