Which weld joint type is most likely to be susceptible to lamellar tearing?

Which weld joint type is most likely to be susceptible to lamellar tearing?

• A. Butt joints
• B. Lap joints
• C. T-joints
• D. Corner joints

Answer: (C)

Lamellar tearing happens when the shrinkage of a weld is restrained by the surrounding thick base metal, creating tensile stresses along the planes of the steel’s lamellae parallel to the plate surface. A T-joint imposes the greatest restraint because the weld connects a plate edge to another plate, producing opposing reactions from both members and a long restraint path at the weld root. That concentration of restrained shrinkage drives shear along those lamellar planes in the heat-affected zone, making tearing along the laminated structure more likely to propagate. Other joint geometries provide fewer restraint conditions in the critical direction, so they are less prone to this defect. Practically, reducing heat input, applying preheating, using appropriate post-weld heat treatment, and adjusting welding sequence or adding stiffeners can help lessen the risk.

Lamellar tearing happens when the shrinkage of a weld is restrained by the surrounding thick base metal, creating tensile stresses along the planes of the steel’s lamellae parallel to the plate surface. A T-joint imposes the greatest restraint because the weld connects a plate edge to another plate, producing opposing reactions from both members and a long restraint path at the weld root. That concentration of restrained shrinkage drives shear along those lamellar planes in the heat-affected zone, making tearing along the laminated structure more likely to propagate. Other joint geometries provide fewer restraint conditions in the critical direction, so they are less prone to this defect. Practically, reducing heat input, applying preheating, using appropriate post-weld heat treatment, and adjusting welding sequence or adding stiffeners can help lessen the risk.