warmteaffected

Warmteaffected, commonly referred to in English as the heat-affected zone (HAZ), is the region of a metallic base material that has not melted but has experienced significant thermal exposure during processes such as welding, cutting, or heat treatment. This zone lies adjacent to the weld or processed area and is distinguished from both the unaffected base metal and the fusion zone where the metal has melted.

The thermal cycle in the warmteaffected zone can cause microstructural changes without melting the metal. Peak temperatures, heating and cooling rates, and holding times determine the extent of these changes. Typical effects include grain growth, phase transformations, precipitation or dissolution of alloying constituents, and tempering; these changes alter mechanical properties such as hardness, strength, toughness, and residual stress.

Impact and assessment: The warmteaffected zone can exhibit increased hardness and reduced toughness, or conversely, softer and more ductile behavior, depending on the material and process. Residual stresses resulting from uneven heating and cooling can contribute to distortion or cracking susceptibility, including hydrogen-induced cracking in susceptible steels. Characterization is commonly performed through hardness testing, metallographic examination, and non-destructive methods to map property changes across the weld region.

Control and mitigation: Reducing adverse effects involves optimizing heat input, controlling cooling rates, and using preheating or interpass heating to slow cooling. Post-weld heat treatment (PWHT) can relieve residual stresses and restore desirable properties. Material selection and welding procedure specifications, including filler metal compatibility, also play a critical role in managing the warmteaffected zone.

In practice, the warmteaffected zone is a key consideration in welding metallurgy, structural integrity, and failure analysis across industries such as construction, pipelines, shipbuilding, and manufacturing.