Why does nodular cast iron have higher mechanical properties than gray cast iron and malleable cast iron?
The key is that carbon exists in the form of cast iron. Carbon in gray cast iron exists in free flake graphite, which has a great influence on the weakening of matrix. Malleable cast iron is better than malleable cast iron. Carbon exists in the form of flocculating graphite, but in spherical graphite. In cast iron, carbon exists in the form of spherical graphite, which has little effect on the weakening of matrix and higher mechanical properties.
Due to the extremely low fracture sensitivity of ductile iron, high mechanical properties are directly formed.