Research On Delamination Defect Of Ship Plates

The author tracked and investigated the production process of ship steel in Jinan Iron and Steel Company and found the reseaons of plate delamination. Through the optical miroscope, SEM and energy spectrometer analysis of fracture appearance, obversation of microstructure and inclusions, comparing the qualified and non-qualified products, the effects of micrustructure segregation, inclsion and rolling scheme on delamination of high-strength ship plate. The following conclusions can be drawn:(1)The delamination defect of plates is mainly due to the microstructure segregation of banding bainite at the centre of thickness of plates, the cavity and inclusions in plates.(2)The application of high reduction ratio during rolling process to increase the permeability of deformation can reduce the possibility of defects and decrease the rate of delamination.(3) The delamination defect can be decreased or eliminated by decreasing the segregation at the centre of cast slabs using clean refining and adjusting the refining and rolling schemes.(4)Through controlled rolling and cooling, the shape and distribution of inclusions can be improved, and the effect of banding microstructure formed during rolling process on property can be reduced.