Lamellar Tearing
A lamellar tear in the base material parallel to the rolling plane, caused by high shrinkage stresses in the through-thickness direction. Occurs especially with insufficient steel cleanliness.
Physical-Chemical Mechanism of Action
A lamellar tear is a lamellar crack in the base material that occurs parallel to the rolling plane. It is caused by high shrinkage stresses in the through-thickness direction. These stresses occur when the steel transitions from the liquid phase to the solid phase during cooling and decreases in volume.
Metallurgical Relevance & Risks in Welding
A lamellar tear can lead to serious material failure, as it significantly impairs the mechanical strength of the steel. It can lead to cracks and fractures, especially under load. The cause is often insufficient steel cleanliness, which leads to impurities that contaminate the microstructure and cannot properly accommodate stresses.
Workshop Practice & Action Instructions
To avoid lamellar tears, it is crucial to keep the steel clean and pure before welding. This can be achieved through careful cleaning and the use of high-purity welding consumables. In addition, the cooling steps should be controlled and slow to minimize stresses in the steel. Under heavy loads, it is advisable to perform additional hardening treatment.