QT400-18 ductile cast iron QT400-18

QT400-18 nonporous cast iron QT400-18 low tensile strength and ductility, but casting performance and damping properties, mainly used for casting automobile engine cylinders, cylinder liners, lathe bed to withstand the pressure and vibration components. Chemical composition: For parties when the technical conditions contained in the chemical composition of inspection requirements, demand side regulations. Detection frequency and quantity of the chemical composition of the supply and demand sides agreed or determined by the supplier themselves. For side when not required chemical composition, the chemical composition of their own determination by the supplier, the chemical composition of the casting is not as a basis for acceptance. However, the chemical composition of the selection must meet the requirements to ensure that the casting material microstructure and mechanical properties required by this standard. Spectroscopy for chemical analysis performed in the provisions of GB / T 4336's. Casting conventional chemical analysis method according to GB / T 223.3, GB / T 223.4, the provisions of GB / T 223.60 executed. Mechanical properties: σb ≥200Mpa Application Examples 1. General machinery manufacturing casting more important, such as: cylinder, gear, base, metal cutting machine bed and the bed; etc. 2. cars, tractors and the cylinder block, cylinder head, pistons, brake wheel, coupling plate and piston rings of gasoline and diesel engines with a measurement plane 3. The test build, such as: crossed flat, V-shaped iron, flat feet, a level 4 framework bear the following medium pressure 7.85MPa hydraulic cylinders, pump, valve and require a certain corrosion resistance of the pump casing, container, such as submersible pump pump, pump cover, impeller etc. 5. circumferential speed> 12 ~ 20m / s pulley and other Ⅰ for compliance with the conditions set out in Part 6. surface hardening of parts subject to the carbon content of more than 2% of the iron-carbon alloys. Industrial carbon content of cast iron is generally 2.5% to 3.5%. More carbon in cast iron exists in the form of graphite, and sometimes the form of cementite exist. In addition to carbon, the iron also contains 1% to 3% silicon, and manganese, phosphorus, sulfur and other elements. Alloy cast iron also contains nickel, chromium, molybdenum, aluminum, copper, boron, vanadium and other elements. Carbon, silicon is the main element affecting the microstructure and properties of cast iron. Cast iron can be divided into: ① gray cast iron. Organization of gray cast iron consists of two parts graphite and matrix components. The substrate may be ferrite, pearlite or ferrite and pearlite, the equivalent structure of the steel. So the organization can be seen as cast iron distribution of graphite on steel substrate. Gray cast iron include ordinary gray cast iron and bred FI cast two kinds. Gray cast iron cheap, the most widely used in the total production of all kinds of cast iron, gray cast iron accounted for more than 80.o%. Factors affecting the organization and performance of gray cast iron is mainly chemical composition and cooling rate. Gray cast iron of carbon, silicon content is generally controlled at 2.5% to 4.0% carbon, silicon 1.0% to 3.0%. ② ductile iron. Ductile iron is in the 1950s developed a high-strength cast iron materials, the comprehensive mechanical depression can be close to steel, due to good casting performance, low cost, easy to manufacture, in the industry has been widely used. Ductile iron composition requirements more stringent, compared with gray cast iron, its high carbon content, typically vary within a range of 4.5% ~ 4.7%, in order to facilitate the graphite ball. Far more than the tensile strength of ductile iron gray cast iron, and steel considerably. So for parts under static load, using ductile than steel also saves material, and lighter weight. Different ductile matrix, performance varied widely, ductile iron has good fatigue strength, experiments show that ductile iron torsional fatigue strength even more than 459 steel. In practice, most of the parts are subjected to dynamic loading or with perforated shoulder, nan was invited here by Dai Yi graphite iron to steel some important parts, such as crankshaft, connecting rods and camshafts. ③ Yan base cast iron. Compacted graphite iron is the last ten years to develop a new type of high-strength cast iron materials. Its strength is close to nodular cast iron, and has a certain toughness and high wear resistance; while there are gray iron casting properties and good thermal conductivity. Compacted graphite iron is added to an appropriate amount of vermicularizing treated in a certain ingredient iron and Tempered. Vermicularizing is mainly made of magnesium alloy, magnesium alloy rare earth or rare earth magnesium calcium alloy. Compacted graphite iron production mainly for the production of cylinder heads, cylinder liners, ingot molds and hydraulic valve castings. ④ malleable iron. Malleable cast iron is made by means of a high-strength cast iron White annealed obtained. It has high strength, ductility and toughness, can be partially replaced by steel. By annealing methods, this cast has a black heart and from the heart of two types. Black heart malleable cast iron rely graphitization annealing to obtain; white heart malleable cast iron oxidation and decarbonization annealing to use the system. Malleable iron used to produce complex shapes, to withstand shock and vibration loads of parts, such as fittings and low pressure valves. These parts with steel production, because of poor casting properties, the process is quite difficult, but when using gray cast iron, they can not meet the requirements of a performance problem. Compared with ductile iron, malleable iron has a low cost, quality, technology and simple handling. Especially for thin-walled castings, ductile iron also easy to generate white, the need for high-temperature annealing, then the use of malleable iron is more appropriate. ⑤ cast iron. Adding some alloying elements in cast iron is obtained. Cast iron is cast iron under abrasive wear conditions of work, it should have a high and uniform hardness. White Iron in the case of this type of cast iron. But white cast iron brittle, can not withstand the impact load, so often used in the production of chilled approach to obtain cast iron. ⑥ heat resistant cast iron. Resistant cast iron is cast at high temperatures, such as the furnace floor, heat exchanger, the crucible, heat treatment furnace and other transportation chain. Join in gray cast iron, aluminum, silicon and cadmium and other elements, on the one hand in the casting dense surface oxide film, obstruction to oxidation; on the other hand increase the critical temperature of cast iron, the matrix becomes a single phase of ferrite does not occur graphitization process, thus improving the heat resistance of cast iron. ⑦ corrosion resistant cast iron. Corrosion of cast iron is mainly used in chemical components, such as valves, pipes, pumps, containers. Added silicon in cast iron, chromium, aluminum, molybdenum, copper and nickel and other alloying elements, the casting surface protective film, or the matrix electrode potential increases, can improve the corrosion resistance of cast iron. Common corrosion resistant high silicon cast iron, high silicon molybdenum, aluminous and high chromium cast iron corrosion.