martensittisiin

Martensite is a hard, brittle phase that forms in steel through a rapid cooling process known as quenching. When steel is heated to a high temperature and then cooled quickly, the carbon atoms do not have enough time to diffuse out of the iron lattice and form softer phases like pearlite. Instead, they become trapped within the iron crystal structure, distorting it and creating a body-centered tetragonal structure. This distortion is what gives martensite its characteristic hardness and brittleness. The specific properties of martensite depend on the composition of the steel and the cooling rate. While its hardness is desirable for many applications, its brittleness can be problematic. To mitigate this, martensitic steel is often tempered, which involves reheating it to a lower temperature to reduce brittleness while retaining a significant portion of its hardness. This tempering process allows for a better balance of strength and toughness. Martensitic transformation is a diffusionless transformation, meaning the atoms do not move long distances. Instead, they undergo a coordinated shear movement. The formation of martensite is a key metallurgical phenomenon in the heat treatment of steels.