Question

Which of the following is in the decreasing order of hardness in Rockwell C-scale?

• A. Bainite, Martensite, Fine Pearlite, Coarse Pearlite
• B. Martensite, Bainite, Fine Pearlite, Coarse Pearlite
• C. Coarse Pearlite, Fine Pearlite, Bainite, Martensite
• D. Martensite, Bainite, Coarse Pearlite, Fine Pearlite

Hint:

Always remember: Martensite is the hardest due to its BCT structure. Finer microstructures (like fine pearlite) are harder than coarser ones, and bainite sits in between martensite and pearlite.

Answer 1

The Correct Option is B

The Rockwell C-scale is used to measure the hardness of materials, especially steels and alloys. The hardness generally reflects the material's resistance to deformation or penetration.
Martensite is the hardest microstructure formed in steels due to rapid quenching. It has a highly strained body-centered tetragonal (BCT) structure.
Bainite is formed at a slower cooling rate and has a hardness between that of martensite and pearlite.
Fine Pearlite is harder than coarse pearlite due to its finer lamellar spacing, which increases the resistance to dislocation motion.
Coarse Pearlite, having wider lamellar spacing, is the softest among the options.
Therefore, the correct decreasing order of hardness is: Martensite > Bainite > Fine Pearlite > Coarse Pearlite.