Lamination Defect Reason Analysis of A32/A36 Ship Steel Plate and Smelting Technics Improvement

Some phenomenon of lamination appeared after the tensile test of A32/A36 ship plate steel. The metallographic microscopy, scanning electron microscopy and energy spectrometer were carried on the analysis for the serious lamination defects. The results indicated that the lamination defects were mainly concerned with Nb, Ti carbide and the sulfide mixture formed by element segregation in casting plate. By the observation to steel making and steel rolling process, relevance measures and improvement such as smelting and rolling were proposed and applied to reality. The defective index was reduced from 12% to 5%.