Lamellar Tearing
Lamellar tearing is a step-like cracking that occurs in the base material beneath a weld in heavy plate, parallel to the rolling plane, caused by through-thickness tensile shrinkage stress acting on non-metallic inclusions.
Definition
Lamellar tearing is a problem in T-joints and corner welds on heavy plate. It is prevented by using through-thickness ductile (Z-quality) steel and by joint designs that minimize through-thickness restraint. UT detection requires straight-beam scanning from the plate edge.
How this damage forms
Step-like cracking in base metal beneath highly restrained welds, driven by through-thickness contraction strain acting on planar inclusions in rolled plate — the failure mode low through-thickness ductility makes possible.
How it is detected
UT finds the terraced cracking under attachment welds; the tell is location (parallel to surface, in base metal, under a restrained joint) rather than in the weld itself.
What causes it, and what prevents it
Prevention beats detection: joint design that reduces through-thickness demand, buttering layers, and Z-grade plate (through-thickness tested per EN 10164 or equivalent) at critical attachments. It shows up in heavy structural connections, nozzle attachments and lifting lugs — anywhere a stiff weld pulls across the plate thickness.
Codes that govern assessment
AWS D1.1 commentary and EN 1011 address susceptible details; plate to EN 10164 / ASTM A770 offers through-thickness guarantees.
The common reporting error
Examining only the weld on restrained attachments. The tearing is in the plate under the joint — a weld-volume-only scan pattern passes right over it.
Where Lamellar Tearing fits in an inspection programme
A term is only useful when it connects to a decision. Lamellar Tearing appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.
Related terms
- Lamination — A lamination is a planar separation in rolled plate or pipe parallel to the rolling direction, caused by non-metallic inclusions, gas pockets, or porosity in the original ingot, that opens up during rolling.
- Crack — A crack is a linear discontinuity in a material with negligible opening width, resulting from stress, fabrication, or in-service damage, and is the most safety-critical defect type in pressure equipment and structures.
Further reading
lamellar tearing inspection in heavy forgings
More defect terms
Lack of Fusion · Lack of Penetration · Slag Inclusion · Porosity · Undercut · Overlap · Burn-Through · Weld Spatter · Hydrogen-Induced Cracking · Stress Corrosion Cracking
Where this comes up in practice
Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.
Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.