What is lamellar tearing?
Lamellar tearing is failure of steel in the dimension perpendicular to the plane of rolling. It occurs in steel at heavy, restrained welded joints (usually with plates more than 1 1/2 inch thick) in the form of microscopic cracks. These are often internal and in these cases must be detected ultrasonically, but they may sometimes be seen at the surface. Tearing develops soon after welding. The critical expansion from the heat of welding occurs in the weld. When the weldment at a restrained joint cools the resulting contraction may tear the steel. The phenomenon is said to be an old problem but the term lamellar tearing has only been applied to it in recent years. Occurrences have been more frequent lately because welded buildings have been increasing in size and requiring larger structural members. A serious example of lamellar tearing occurred in the steel compression ring of a performing arts center in El Paso, Texas. This 138-foot-diameter ring is located between two intersecting crescents of the theater. Construction of the $5-million structure has been delayed more than a year and the price has been increased by several hundred thousand dollars for inspection and repair. On the twin 52-story Atlantic-Richfield towers in Los Angeles repair required because of lamellar tearing cost $400,000. The compression ring of the El Paso structure is a box girder with a cross section of 2 by 4.6 feet. Great, full-penetration welds join its 2.5- to 3inch-thick flange plates to 1-inch-thick diaphragm plates to tie its 25 sections together. The American Institute of Steel Construction devoted a major part of its May 1972 national engineering conference to a study of the problem.