Factors affecting the performance of gray cast iron

Gray cast iron refers to cast iron with flake graphite. It is called gray cast iron because the fracture is dark gray when it breaks. The main components are iron, carbon, silicon, manganese, sulfur, and phosphorus. It is a widely used cast iron.

According to the form of graphite, gray cast iron can be divided into: ordinary gray cast iron, graphite is flake; ductile cast iron, graphite is spherical; malleable cast iron, graphite is flocculent; vermicular cast iron, graphite is worm-like.

① The influence of chemical composition. The main control in production is the mass fraction of carbon and silicon. When the mass fraction of carbon and silicon is too low, the cast iron is prone to white cast iron structure, and the mechanical properties and casting properties are very low; when the mass fraction of carbon and silicon is too high, the graphite flakes are too many and coarse, and even graphite floats on the surface of the molten iron, reducing the performance and quality of the casting.

② The influence of cooling rate. Under certain casting process conditions, the cooling rate of the casting has a great influence on the degree of graphitization. As the wall thickness of the casting increases, the cooling rate slows down, and the carbon atoms have sufficient diffusion time, which is conducive to the full graphitization process, and the room temperature structure is easy to form gray cast ironstructure; but thin-walled parts are cooled too quickly during the cooling process, which is easy to form white cast iron structure.