Wärmeinflusszonen

Wärmeeinflusszonen, often abbreviated as HAZ, refer to the areas surrounding a weld in a metallic material that experience a temperature change during the welding process. These zones are not melted but undergo microstructural alterations due to the heat input. The extent and nature of these changes depend on the welding parameters, the base metal's properties, and the cooling rate.

The HAZ is typically divided into several sub-regions. Nearest the weld, the coarse-grained zone experiences temperatures high enough for significant grain growth, which can reduce toughness. Further away, a fine-grained zone may form if the peak temperature allows for recrystallization without excessive grain growth. Beyond this, a tempered zone can exist in materials that have been previously heat-treated, where the heat from welding alters the existing microstructure. Finally, the unaffected base metal lies outside the thermal influence.

Understanding and controlling the HAZ is crucial in welding. Undesirable changes, such as embrittlement or hardening, can compromise the mechanical properties and service life of the welded component. Welding procedures and post-weld heat treatments are often employed to manage the HAZ and ensure the integrity of the structure. The size and characteristics of the HAZ are important considerations in weldability assessments and design.