Micro-structural heat-affected zone
The heat-affected zone (HAZ) is the narrow area around the weld where the welding heat causes phase changes or grain growth. Its width depends on the heat input.
Physical-Chemical Effect Mechanism
The microstructural heat-affected zone is created by the thermal effect of the cutting process. This changes the crystal structure and grain size in the metal. Phase transformations like austenite to martensite can occur, increasing hardness.
Metallurgical Relevance & Welding Risks
The microstructural heat-affected zone affects the mechanical properties of the weld. Too thin a zone can lead to fine grains and increased toughness, while too thick a zone results in coarse grains and lower toughness. This can lead to cracks or distortion.
Workshop Practice & Action Instructions
To set the microstructural heat-affected zone optimally, control the heat input during cutting. For high-carbon steels (e.g., HSS), careful cooling is needed to avoid martensite formation. For low-carbon steels (e.g., SS), minimize grain coarsening. Specific temperatures and times vary by material and cutting process.