Plate fracture is a defective fracture structure in nodular cast iron that can be found especially in the transition area of feeder, feeder neck and the cast part itself. It occurs rather spontaneously due to the fact that the exact reason for it is still unknown. The microstructure of the casting in the area of plate fracture comprises aligned graphite nodules in combination with a pronounced dendritic microstructure as characteristical features. A series of casting trials was performed in which plate like samples were produced. It could be shown by means of metallographic investigation of these samples in combination with the simulation of the solidification that specific local conditions during the solidification are the metallurgical reasons for the appearance of plate fracture. These specific conditions were the local temperature gradient and the velocity of the liquid/solid interface.