The energy-saving requirements make the selection of product materials become more important, ductile iron is an increasingly considered material in the metal casting industry due to its great strength-to-weight ratio characteristics and relatively low cost. What is nodular cast iron? Why and when to use it? Take a look at the overview of ductile iron.
Ductile iron, also known as nodular cast iron, ductile cast iron, spheroidal graphite iron, and spheroidal graphite cast iron, is graphite-rich cast iron. Before pouring molten iron, add a small amount of spheroidizing agents, such as magnesium, calcium, and rare earth elements, and graphite agents, such as ferrosilicon and calcium silicon alloy to the molten iron to promote the existence of carbon in spherical graphite. This kind of cast iron is called nodular cast iron.
What advantages does ductile iron have?
Nodular cast iron is a high-strength cast iron material developed in the 1950s. Its comprehensive properties are close to steel. Based on its excellent properties, it has been successfully used to cast some parts with complex stress and high requirements for strength, toughness, and wear resistance. Nodular cast iron has rapidly developed into a widely used cast iron material second only to gray cast iron.
Because carbon (graphite) exists in the matrix of cast iron in a spherical shape, its splitting effect on the matrix is improved, and the tensile strength, yield strength, plasticity, and impact toughness of nodular cast iron are greatly improved. Nodular cast iron is much better than gray cast iron in strength, plasticity, toughness, and even close to steel; It has the advantages of wear resistance, shock absorption, good process performance, and low cost. It has widely replaced malleable cast iron and some cast steel and forged steel parts.
What are ductile iron and ductile iron castings used for?
1. Piping and fittings
Ductile iron pipes are better than gray iron pipes in transporting water and other liquids. The main reason for this transformation lies in the combination of strength and toughness of ferritic nodular cast iron so that the pipeline made of this material can withstand high operating pressure and can be loaded and unloaded carelessly during laying. The mat gas transmission pipeline must be able to withstand the requirements of multiple-use conditions, i.e. excavation near the pipeline, municipal engineering construction, transportation, etc
2. Automotive industry
The automotive industry is the second user of ductile iron castings. Ductile iron is used in three main places in automobiles: the first is engine parts, the second is gears and shaft sleeves, and the third is vehicle suspension, brake, and steering device. Most gasoline engines in the world are equipped with nodular iron crankshafts instead of forged steel crankshafts. Ductile iron with excellent properties is replacing gray cast iron in the exhaust pipe. With the increase of temperature, silicon aluminum alloy ductile iron will be further used. Malleable cast iron parts for automobile power transmission are sometimes used as transmission parts of automobiles. There is a strong trend to apply ductile iron to disc clutch, speed divider box, rear axle, and wheel housing. Ductile iron is often used as suspension components, such as spring hooks, as well as the main safety components of braking systems and steering joints.
3. Agricultural, road, and construction applications
Ductile iron castings widely used in the whole agricultural industry include various tractor accessories, brackets, clamps, and pulleys. The typical component is the two rear axle shells of agricultural vehicles, which originally used steel castings. Road laying and construction industries need a considerable number of various types of equipment, including bulldozers, percussion machines, cranes, and compressors. Ductile iron castings are used in these aspects.
4. Valve manufacturing
Valve manufacturers are the main users of ductile iron (including austenitic ductile iron). Their applications include the successful transportation of various acids, salts, and alkaline liquids.
5. General purposes
The machine tool industry utilizes the engineering properties of ductile iron, which allows the design of complex machine tool parts and castings Ductile iron has high tensile strength and yield strength, and good machinability. It allows the production of lighter castings to keep them rigid. Similarly, the strength and toughness of ductile iron make it an ideal material for various hand tools, such as wrenches, clamps, and measuring tools. Similarly, ductile iron rolls are used in steel mills, which have higher properties than steel and chilled cast iron.