is mainly composed of iron, carbon and silicon in the alloy composition. In these alloys, carbon content than in the eutectic temperature can be retained in the austenite solution in quantity.
Carbon content in more than 2% of iron carbon alloy. General industrial use cast iron carbon content is 2% ～4%. Carbon in cast iron by graphite form, sometimes with cementite existence. In addition to carbon, iron also contains 1% to 3% of silicon, manganese, phosphorus, sulphur and elemental. Alloy cast iron containing nickel, chromium, molybdenum also, aluminum, copper, boron, vanadium and other elements. Effect of carbon, silicon is iron casting microstructure and properties of main elements. Cast iron can be divided into:
①gray iron casting. The carbon content is higher ( 2.7% ~ 4% ), mainly carbon to graphite flake form, the fracture is gray, referred to as the gray iron. Low melting point ( 1145～ 1250 ℃), solidification shrinkage, compressive strength and hardness to carbon steel, good shock absorption. Used in the manufacture of machine tools, cylinder, box body structure.
②iron casting white. Carbon, silicon content was relatively low, mainly in the presence of carbon cementite morphology, fracture is in silver. Solidification shrinkage, shrinkage, crack is easy to produce. High hardness, brittleness, unable to bear the impact load. As iron casting forging blank and the production of wear resistant parts.
③malleable iron casting. After annealing treatment by white cast iron, graphite was distributed clusters, referred to as the ductile iron. The microstructure and properties of wear resistance, uniform, good plasticity and toughness. Used in the manufacture of complex shape, can withstand the intense dynamic loading parts.
④ductile iron casting. The gray cast iron after spheroidizing treatment after obtaining, precipitation of spherical graphite, referred to as the ductile iron. Than ordinary grey cast iron has high strength, good toughness and plasticity. Used in the manufacture of internal combustion engines, auto parts and other agricultural.
The iron casting vermicular graphite. Gray cast iron will be acquired through vermicularizing treatment, precipitation of graphite in vermicular. Mechanical properties of ductile cast iron casting with similar properties, between gray iron and ductile iron. Used in the manufacture of automobile parts.
The iron casting alloy. Ordinary cast iron by adding alloying elements ( such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, tin, vanadium ) obtained. Alloy element makes the iron matrix structure changes, thereby having corresponding heat, wear and corrosion resistance, low temperature resistance and magnetic properties. Used in the manufacture of mining, chemical machinery and equipment, instruments and other components.