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Wednesday, 15 June 2016

What is difference between Martensite and Bainite

Hello Pals,

  Martensite and Bainite are generally formed by rapid cooling to ambient temperature.Both are hard and metastable phases. lets see few simple differences between Martensite and Bainite.   


Difference between Martensite & Bainite:

Simple explanation for difference:

Martensite : Carbon ferrite

Supersaturated solution of carbon in ferrite formed by diffusion-less phase transformation from austenite.

  • It is BCT(Body Centered Tetragonal).
  • Appearance is acicluer pattern.  
  • Morphology is Lath if C% is less than 0.6%.
  • Morphology is Plate if C% is more than 1.0%. 
  • It is mixture of lath and plate in between 0.6% to 1.0% C. 

Bainite: Nonlamellar  Ferrite cementite

Nonlamellar mixture of ferrite and cementite. Dispersed carbides in ferrite formed by transformation of austenite.

  • Appearance is feathery when formed at higher temperature called upper bainite.
  • Appearance is acicular when formed at lower temperature called lower bainite.
  • There is harness difference according to temperatures, bainite hardness increases with increasing temperature of formation.   
   

      Martensite and Bainite are two very important phases for properties of steel.