Lamellar Tearing
A lamellar tearing is a layered crack in the base material below the weld, caused by high through-thickness shrinkage stresses and insufficient steel cleanliness.
Physico-Chemical Mechanism
A lamellar tear forms in the base metal below the weld as a layered crack. It is caused by high through-thickness shrinkage stresses that occur during cooling. These stresses can lead to plastic deformation and, when the steel has insufficient cleanliness with respect to non-metallic inclusions, to cracking.
Metallurgical Relevance & Welding Risks
A lamellar tear can cause a weld defect because it impairs the strength and mechanical properties of the workpiece. It can also lead to further cracks or deterioration of the weld. Insufficient steel cleanliness regarding non-metallic inclusions increases the likelihood of a lamellar tear.
Shop Practice & Action Guidelines
To avoid lamellar tears, it is important to clean and inspect the steel before welding. Check the steel's cleanliness to ensure there are no non-metallic inclusions. Also, set welding parameters like temperature and time carefully to ensure even cooling.