Ductile iron castings have cast iron with flake graphite when used, and the fracture is dark gray when broken, so it is called gray cast iron. The main components are iron, carbon, silicon, manganese, sulfur and phosphorus. It is a widely used cast iron, and its output accounts for more than 80% of the total output of cast iron.
Gray cast iron is a type of cast iron. Carbon is present in the form of flake graphite in cast iron. The fracture is gray. Good casting, cutting performance and good wear resistance. Used to manufacture racks, cabinets, etc. Gray cast iron graphite is in the form of flakes, the effective bearing area is relatively small, and graphite tends to generate stress concentration, so the strength, plasticity and toughness of gray cast iron are lower than other cast iron. However, it has excellent vibration damping, low notch sensitivity and high wear resistance.
Mechanical properties of gray cast iron castings
The mechanical properties of gray cast iron castings are related to the microstructure of the matrix and the morphology of the graphite. The flake graphite in gray cast iron is severely cracked on the substrate, and it tends to cause stress concentration at the sharp corners of the graphite. The tensile strength, plasticity and toughness of the gray cast iron are much lower than that of the steel, but the compressive strength is equivalent to that of the steel. Cast iron with poor mechanical properties. At the same time, the matrix structure has a certain influence on the mechanical properties of gray cast iron. The graphite sheet of the ferrite matrix gray cast iron is coarse, the strength and hardness are low, so it is less applied.
The graphite sheet of the pearlite matrix gray cast iron is small, has high strength and hardness, and is mainly used to manufacture more important castings; the graphite sheet of the ferrite-pearlite matrix gray cast iron is slightly thicker than the pearlite gray cast iron, and the performance is not as good as that of pearlite. grey cast iron. Therefore, the gray cast iron of the pearlite matrix is used more in the industry.