Posted by Sarup Chopra on April 25, 2008 at 16:55:02:
In Reply to: Martensite posted by Abir Bhattacharyya on April 25, 2008 at 10:09:56:
In case of Iron, Martensite is hard because of the transformation from a face centered cubic lattice (FCC) into a body centered cubic (BCC) lattice at the time of transformation( quenching from the Austenitizing temperature ) which leads to the entrapment of more solute atoms (Carbon in this case) in the body centered cubic lattice than it has a capacity to hold (the prevailing face centered cubic lattice before quenching can accomodate a larger number of solute atoms (Carbon in this case).This in turn creates a lot of strain on the transformed lattice rendering it tetragonal in shape which translates into higher hardness.