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Lamellar tearing: what it is and how to spot it

Fillet Gauge editorial teamSources checked 3 min read

Lamellar tearing is cracking in the base metal under a weld, in thick rolled plate pulled through its thickness by weld shrinkage. It forms in steps: flat terraces parallel to the plate surface, joined by short vertical tears. It belongs to T-joints, corner joints and cruciform joints where the weld pulls at right angles on the through-plate.

A thick through-plate in cross-section with a stem plate welded on top by fillets on both sides, and step-shaped cracks in the through-plate beneath the welds
Flat terraces joined by short steps, all in the base metal. Original drawing, not to scale.
Use this diagram

How to recognize lamellar tearing

  1. Check the joint type. Lamellar tearing needs a weld that pulls through the thickness of a plate. T, corner and cruciform joints on thick plate are the usual places. A butt weld between two plates in line rarely causes it.
  2. Look in the base metal, not the weld. The tear is in the through-plate under or just beside the weld, often just outside the heat-affected zone.
  3. Look for steps. Where it breaks out at a plate edge or shows in a section, its shape is distinctive: a staircase of flat runs and short risers.
  4. Expect to need NDE. Most tears are hidden under the weld. A tear that reaches the edge of the through-plate may be visible there.

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Welding Inspection and Discontinuities

A convex fillet weld replica is checked with a leaf-type fillet gauge. The drawing calls for a single fillet size. The vertical leg fits the 3/8 in blade and the horizontal leg the 5/16 in blade. What size is recorded?

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How it is found

Ultrasonic testing finds lamellar tears, because most of each terrace is flat and parallel to the surface, like a lamination. Inspecting the through-plate with straight-beam ultrasonic testing before welding, to find laminations and inclusion bands that could start a tear, is common on critical joints. At exposed edges, magnetic particle or penetrant testing confirms a tear. Radiography is poor at finding it, for the same reason it misses laminations.

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Every answer comes with a full explanation.

Common mix-ups

  • Lamellar tearing or lamination. A lamination is in the plate from the mill. A lamellar tear forms because of welding, and its step shape gives it away.
  • Lamellar tearing or an underbead crack. An underbead crack follows the hardened zone next to the fusion line. A lamellar tear runs in steps parallel to the plate surface, often farther out.
  • Lamellar tearing or a toe crack. A toe crack starts at the toe and heads down into the plate. A lamellar tear runs sideways under the weld.

Why it forms and how it is prevented

Rolled plate has flattened nonmetallic inclusions lying in planes. They give the plate poor ductility through its thickness. When a large weld on the face of that plate shrinks, it pulls the planes apart. Prevention works on each part: specify steel with improved through-thickness properties, change the joint so the weld pulls less through the thickness, use smaller welds or a buttering layer, and use low-hydrogen practice, since hydrogen raises the risk.

Lamellar tearing on the CWI exam

On Part A, lamellar tearing fits Base Materials, Heat Treatments and Metallurgy, where plate properties are covered, and NDE Fundamentals for method choice. On Part B it fits Welding Inspection and Discontinuities and NDE Application. On Part C, look in your own copy of the code for joint details and through-thickness requirements that address it.

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Drill which NDE method sees a flat, stepped flaw in the NDE methods quiz. Then read the mill flaw that sets it up, lamination, and the hydrogen crack it is often confused with, underbead cracks. Every type is in the weld discontinuities guide.

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Facts checked 25 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.

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