The term “martensite” usually refers to a form of steel with a distinctive atomic structure created through a process called martensitic transformation. Martensite is made from austenite, a solid solution of iron with a small amount of carbon in it.

Martensite definitionchemistry

Martensite definitionengineering

Martensite is a body-centered tetragonal form of iron in which some carbon is dissolved. Martensite forms during quenching, when the face centered cubic lattice of austenite is distored into the body centered tetragonal structure without the loss of its contained carbon atoms into cementite and ferrite. Instead, the carbon is retained in the iron crystal structure, which is stretched slightly so that it is no longer cubic. Martensite is more or less ferrite supersaturated with carbon. Compare the grain size in the micrograph with tempered martensite.