The different microstructures of steel at varying temperatures are primarily influenced by the crystal structures of iron, which transition from body-centered cubic (BCC) in ferrite at lower temperatures to face-centered cubic (FCC) in austenite at higher temperatures. The addition of carbon alters the iron lattice, creating solid solutions that enhance properties like strength and ductility. Temperature affects atomic mobility and the energy of the system, favoring the FCC structure in austenite due to its ability to accommodate more carbon and other alloying elements. The iron-carbon equilibrium diagram illustrates these transformations and their relationship with temperature and carbon content. Understanding these principles is crucial for manipulating steel properties for various applications.
