martenzitizáció

Martenzitizáció is a metallurgical term referring to the process of forming martensite in steel. Martensite is a very hard, brittle, and metastable phase of steel. It is characterized by its body-centered tetragonal crystal structure, which is a distorted version of the body-centered cubic structure of ferrite. This distortion arises from the trapped carbon atoms within the iron lattice during rapid cooling.

The process of martensitization involves heating steel to a temperature above its critical point (austenite phase) and then rapidly cooling it. This rapid cooling, often referred to as quenching, is crucial. If the cooling rate is slow, the carbon atoms have time to diffuse out of the iron lattice and form more stable phases like pearlite or bainite. However, with a sufficiently fast quench, the carbon atoms become trapped, leading to the formation of the strained martensitic structure.

The specific temperature to which the steel is heated and the quenching medium used (e.g., water, oil, air) influence the final microstructure and properties. The amount of martensite formed and its specific characteristics depend on the carbon content of the steel and the cooling rate. Martensite formation is a diffusionless transformation, meaning the atoms do not rearrange themselves significantly; rather, the crystal lattice distorts. This hard phase is often the result of heat treatment processes like hardening and tempering, where subsequent tempering reduces brittleness while retaining significant hardness.