Bainite transformation starts after nucleation of ferrite phase

Q.  Which transformation starts after the nucleation of ferrite phase?
- Published on 11 Sep 15

a. Bainite transformation
b. Pearlite transformation
c. Both a. and b.
d. None of the above

ANSWER: Bainite transformation


  • Sravanthi    -Posted on 12 Nov 15
    - The ferrite nuclei starts precipitating below 500°C at austenite grain boundary.

    - After the nucleation of ferrite phase, bainite transformation starts. This transformation occurs at low temperatures and hence nucleation rate of ferrite is high and the growth rate is slow because at low temperatures less mobility of carbon atoms is observed.

    - The solubility of carbon is very less in ferrite as ferrite nuclei grow. Hence, cementite starts precipitating in small particles in soft ferrite of matrix.

    - Bainite formed at higher temperature is called as upper bainite (Forms at temperature between 550°C to 400°C) and bainite formed at low temperature is called as lower bainite (Forms at temperature between 400°C to 250°C)

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