Lamellar tearing

Figure 15. Off-shore platform node construction showing the complex welding assembly job requiring outstanding resistance to lamellar tearing in the electric-resistance-welded (ERW) steel pipe stock. Excellent through-thickness ductility is obtained by low sulfur plus REM treatment in the ladle, plunging a mischmetal...

FIGURE 21.11 Lamellar tearing in a T-joint. Copyright by Marcel Dekker, Inc. reprinted with permission [5]. 

Postweld inspection for lamellar tears is difficult unless the tears penetrate to the surface (usually at the toe of the weld). Dye penetrant inspections are reliable for tears that penetrate the surface. For embedded tears, ultrasonic inspection is sometimes used, but tears are difficult to differentiate from noninjurious inclusions. 

Flange Plates were tested for Lamellar Tearing (through thickness testing) prior to assembly. 

Unresolved Safety Issue (USI) A-12 in NUREG-0933 (Reference 1), addresses minimizing the susceptibility for lamellar tearing and low fracture toughness of major reactor coolant system (RCS) component supports. 

NUREG-0577 Revision 1, "Potential for Low Fracture Toughness and Lamellar Tearing in PWR Steam Generator and Reactor Coolant Pump Supports", U. S. Nuclear Regulatory Commission, October 1983. 

NUREG-0577, Revision 1, Potential for low fracture toughness and lamellar tearing in pwr steam generator and reactor coolant pump supports, US Nuclear Regulatory Commission (October 1983). 

Lamellar tearing is generally found in the HAZ of weldments of tee and corner joints. The cause of cracking appears to be inclusions that are parallel to the rolling direction of the plate section being welded. The restraining forces in the welded joint cause the inclusions to open up and run together to form a crack. Set on-type connections welded to heavy sections are particularly susceptible to this type of defect. Where set on-type connections are used, shear-wave ultrasonic inspection of the plate in the area of the attachment and of the completed weld is recommended. 

Cracking that occurs in the weld metal. See also cold cracking, hot cracking, lamellar tearing, and... 

Several researchers have revealed a marked effect of rare earths on improving the thicknesswise ductility of steels resistant to lamellar tear, reducing the anisotropy of steels, and preventing hydrogen-induced cracking, etc. Basically, all these seem to be attributable to the following four principal functions achieved by rare earths and Ca addition to the molten steels ... 

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