Ferrite-Austenite Phase Boundary
The ferrite-austenite phase boundary is the interface between body-centered cubic ferrite and face-centered cubic austenite in steels. Diffusion of atoms occurs here, affecting the growth of new phases.
Physicochemical mechanism of action
The ferrite-austenite phase boundary is an interface between body-centered cubic ferrite (α-phase) and face-centered cubic austenite (γ-phase). At this boundary, diffusion processes occur where atoms transfer from one phase to the other. This diffusion affects the growth of new phases and can lead to a homogeneous microstructure.
Metallurgical relevance & risks in welding
Proper handling of the ferrite-austenite phase boundary is critical for weld quality. If the temperature during welding is too high or too low, unwanted phase transformations can occur, such as excessive formation of martensite, which can be glass-hard and crack-prone. This can lead to cracks and distortion in the weld joint.
Workshop practice & instructions
To handle the ferrite-austenite phase boundary correctly, welding parameters such as temperature and time must be precisely controlled. For steels with high austenite content (e.g., HSS), the welding temperature should be kept below the austenite-ferrite phase boundary to avoid martensite formation. For low austenite content, it is important to keep the temperature above this boundary to ensure a homogeneous austenite structure.