Kerf Microcrack
A microscopic crack at the cut edge, caused by thermal residual stresses and microstructural transformations.
Physical-Chemical Mechanism of Action
Welding generates high temperatures that change the metal's state (e.g., from solid to liquid). This causes stresses and transformations in the structure. If the metal cools rapidly, these stresses cannot be relieved, leading to microscopic cracks at the cut edge.
Metallurgical Relevance & Welding Risks
Cut joint micro-cracks can lead to further mechanical defects, such as hot cracks or deformation. They grow under continued loading and can significantly shorten the weld's service life.
Workshop Practice & Action Instructions
To minimize cut joint micro-cracks, ensure controlled cooling. This can be achieved by using cooling water or special cooling gases. Do not quench the weld directly in cold water, as this causes sudden stresses. An optimal cooling process is critical for weld quality.