The difference between cast steel and cast Iron and carbon alloy containing a small amount of alloying elements and impurities in steel, according to the different carbon content can be divided into: pig iron – containing C 2.0 to 4.5% steel – C containing 0.05 to 2.0% cooked Iron – less than 0.05% C Iron is an iron-carbon alloy containing more than 2% carbon.
Industrial cast iron is generally carbon content of 2% to 4%. Carbon is mostly found in graphite in the form of graphite, sometimes in the form of cementite. In addition to carbon, cast iron also contains 1% to 3% of silicon, as well as manganese, phosphorus, sulfur and other elements. Alloy cast iron also contains nickel, chromium, molybdenum, aluminum, copper, boron, vanadium and other elements. Carbon and silicon are the main elements that affect the microstructure and properties of cast iron.
Cast iron can be divided into:
- gray cast iron. Carbon content is higher (2.7% ~ 4.0%), carbon is mainly in the form of flake graphite, gray fracture, referred to as gray iron. Low melting point (1145 ~ 1250 ℃), when the shrinkage of small solidification, compressive strength and hardness close to the carbon steel, good shock absorption. For the manufacture of machine bed, cylinder, box and other structural parts.
- white cast iron. Carbon and silicon content is lower, carbon is mainly in the form of cementite, the fracture is silvery white. Shrinkage when solidified, easy to produce shrinkage, cracks. High hardness, brittleness, can not withstand the impact load. Used as a malleable cast iron parts and wear-resistant parts.
- malleable iron. Obtained from the white cast iron annealed, graphite was flocculent group distribution, referred to as tough iron. Its uniform organizational performance, abrasion resistance, good ductility and toughness. For the manufacture of complex shapes, can withstand strong dynamic load parts.
- ductile iron. The gray cast iron molten iron obtained by the ball after the precipitation of graphite was spherical, referred to as ductile iron. More than the average gray cast iron has high strength, good toughness and plasticity. For the manufacture of internal combustion engines, auto parts and farm machinery and so on.
- compacted graphite iron. The gray cast iron hot metal obtained after the vermicular treatment, precipitated graphite was worm-like. Mechanical properties and ductile iron similar casting performance between the gray cast iron and ductile iron. Used to make car parts.
- alloy cast iron. Ordinary cast iron by adding the right amount of alloying elements (such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, vanadium, tin, etc.). Alloying elements of the matrix of cast iron changes, which have the corresponding heat, wear resistance, corrosion resistance, low temperature or non-magnetic properties. For the manufacture of mines, chemical machinery and instruments, meters and other components.
Steel used to cast castings. Cast a kind of alloy. Cast steel is divided into cast carbon steel, cast low alloy steel and special steel casting 3 categories.
- cast carbon steel. Cast steel with carbon as the main alloying element and with a few other elements. Less than 0.2% of carbon for the casting of low carbon steel, carbon 0.2% to 0.5% for the casting of medium carbon steel, carbon greater than 0.5% for the casting of high carbon steel. As the carbon content increases, the strength of the cast carbon steel increases and the hardness increases. Cast carbon steel with high strength, ductility and toughness, low cost, used in heavy machinery for the manufacture of large load bearing parts, such as rolling mill chassis, hydraulic press base, etc .; in railway vehicles used to create large force And bear the impact of parts such as bolsters, side frames, wheels and coupler and so on.
- casting low alloy steel. Cast steel containing manganese, chromium, copper and other alloying elements. The total amount of alloying elements is generally less than 5%, with greater impact toughness, and can be obtained by heat treatment better mechanical properties. Casting low alloy steel than carbon steel has excellent performance, can reduce the quality of parts, improve service life.
- casting special steel. To meet the special needs of the refining of alloy steel, a wide variety, usually containing one or more of the high amount of alloying elements in order to obtain a special performance. For example, high manganese steel containing 11% ~ 14% manganese can be impact-resistant and wear-resistant, and is mainly used for wear-resistant parts of mining machinery and construction machinery. Various stainless steels containing chrome or chrome nickel as the main alloying element are used in corrosion- ℃ above the working conditions of high temperature parts, such as chemical valves, pumps, containers or large-capacity power station turbine casing.