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Pump parts (grey iron)
The company primarily focuses on small to medium-sized castings ranging from 0.2 to 2000 kg, using materials such as various grades of gray iron, ductile iron, and alloyed cast irons. Our product range includes pipe fittings, housing components (made from gray cast iron), end caps (also gray cast iron), bases (gray cast iron), motor accessories (crafted from ductile iron), pump housings (also made from ductile iron), machined parts, and more.
Category:
Keywords:
Pipe Fittings | Gray Cast Iron | Ductile Cast Iron
Product Details
Ductile iron is produced through spheroidization and inoculation treatments that form spherical graphite, significantly enhancing the mechanical properties of cast iron—particularly improving plasticity and toughness—thereby achieving strength surpassing that of carbon steel.
Ductile iron is an iron-carbon alloy with a carbon content exceeding 2.11%. It is produced by high-temperature melting and casting of industrial pig iron, scrap steel, and other ferrous materials and their alloys. Besides iron, it contains carbon that precipitates as graphite in the form of flakes. When graphite precipitates as flake-like structures, the cast iron is called gray cast iron or gray iron; when worm-like, it is called vermicular graphite iron; when flocculent, it is called malleable iron or malleable cast iron; and when spherical, it is called ductile iron.
The typical chemical composition of ductile iron, excluding iron, is: carbon content 3.0–4.0%, silicon content 1.8–3.2%, total manganese, phosphorus, and sulfur not exceeding 3.0%, plus appropriate amounts of spheroidizing elements such as rare earths and magnesium.
Precautions for Ductile Iron:
(1) Strictly control chemical composition. The carbon and silicon content of the original molten iron must be higher than that of gray cast iron, while reducing the manganese, phosphorus, and sulfur content in ductile iron.
(2) The pouring temperature of molten iron should be higher than that of gray cast iron to compensate for temperature loss during spheroidization and inoculation treatment.
(3) Perform spheroidization treatment by adding a spheroidizing agent to the molten iron.
(4) Add inoculants for inoculation treatment.
(5) Ductile iron exhibits poorer fluidity and greater shrinkage, necessitating higher pouring temperatures and larger pouring system dimensions. Proper application of risers and chill blocks is required, adhering to the principle of sequential solidification.
(6) Heat treatment is performed:
① Annealing: Produces a ferritic matrix, enhancing plasticity and toughness, relieving stresses, and improving machinability.
② Normalizing: Produces a pearlitic matrix, increasing strength and wear resistance.
③ Quenching and tempering. Produces a tempered sorbite matrix structure with excellent comprehensive mechanical properties, suitable for components like spindles, crankshafts, and connecting rods.
④ Isothermal quenching. Achieves a lower bainite matrix structure with high strength, hardness, and toughness for complex-shaped parts demanding superior comprehensive properties, while preventing cracking during heat treatment. Applicable to components such as spindles, crankshafts, and gears.
The basic characteristic of high-density molding sand for gray iron castings is that the amount of coal powder added is also relatively low. Therefore, the following points should be taken into account when preparing sand.
1. Clay content and mud content. The strength of sand with high clay content increases with the increase of specific pressure, and the effective bentonite is usually controlled at 7% to 10%. The sum of effective clay and dead clay in molding sand is equivalent to the mud content, which is generally controlled between 12% and 16%. Excessive or insufficient clay content can affect the various performance indicators of the molding sand.
2. Moisture. The moisture content in the molding sand used in the production of lost foam castings is the main factor determining the plasticity and bonding strength of clay. When the moisture content is too high, it can easily cause the deterioration of clay adhesion, decrease the flowability of molding sand, and result in uneven mold density. When the moisture content is too low, the molding sand is difficult to mix evenly, the strength of the molding sand is low, the brittleness is high, the demolding performance is poor, and it is easy to cause sand sticking defects in castings. The general moisture content should be controlled to be 10% to 20% higher than the moisture content at which the peak wet compressive strength is obtained.
3. Original sand particle size. When molding with high density, the sand mold has a high density and expands greatly during pouring. Therefore, the original sand particle size should not be overly concentrated. The original sand particles are circular or polygonal, and generally three or four screen sand is selected.
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TONGREN IND.AND TRADING CO., LIMITED
Phone: 0086-513-83571237
Mobile phone: 0086-13814629071
Email: trgm5f@tr-casting.com
Address: Liuqiao Street, Liuqiao Town, Tongzhou District, Nantong City, China.