Properties of Lamellar Tearing Resistance of Heavy Steel Plate Under Different Superheating

Continuous casting slabs were casted with two superheating. Heavy plates of 70mm in thickness were rolled. Z-direction tensile test of plate was carried out on a tensile testing machine. Microstructure, morphology and composition were analyzed to find out the relationship between slab quality and lamellar tearing resistance by optical microscopy, scanning electron microscopy and energy dispersive spectrometry. Results show that central segregation increases and the amount of equiaxed grains decrease in slab with high superheating. Poor lamellar tearing resistance of plate is obtained because the defects can be inherited after hot rolling. Central segregation, inclusions and the formation of bainite and martensite are the reasons of brittle fracture during Z-direction tensile test.