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Method for preparing nodular cast iron

A technology of ductile iron and molten iron, which is applied in the field of preparation of ductile iron, can solve the problems of low temperature impact toughness and high scrap rate, and achieve the effects of improving roundness, absorption rate and comprehensive performance

Inactive Publication Date: 2014-04-30
CHTC HEAVY IND
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  • Claims
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Problems solved by technology

At present, the smelting process of QT400-18AL ductile iron produced in my country is mainly based on electric furnace smelting, but very few are smelted with cupola furnace, and it is not suitable to meet its requirements for low temperature impact toughness, resulting in a high scrap rate

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  • Method for preparing nodular cast iron

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preparation example Construction

[0027] The preparation method of ductile iron of the present invention is realized through the following steps:

[0028] a. Selection of raw materials: coke: fixed carbon content ≥ 85%, sulfur content < 0.50%, water content < 3%; new iron: carbon content 4.2-4.3%, silicon content: 0.9-1.1%, phosphorus content < 0.040% , sulfur content: <0.020%; steel scrap: low manganese high-quality carbon steel scrap: carbon ≤0.5%, manganese <0.3%;

[0029] b. Adopt cupola oxygen-enriched air supply process to increase the temperature of molten iron: the bottom coke height of cupola is 1800-2000mm, and the batch material is 500kg; among them, new iron is 380-420kg, scrap steel is 80-120kg, coke is 55-60kg; >1450°C;

[0030] c. Spheroidization inoculation treatment: Spheroidization treatment is carried out by using the cover bag method, and the nodulizer rare earth magnesium alloy FeSiMg8Re3 is added into the preheated spheroidization treatment bag, and the amount of nodulizer added is 1.5~ ...

Embodiment 1

[0039] a. Selection of raw materials:

[0040] Shanxi high-quality foundry coke: fixed carbon content ≥ 85%, sulfur content < 0.50%, water content < 3%

[0041] Shanxi high-quality Q10 pig iron: carbon content 4.2~4.3%, silicon content: 0.9~1.1%, phosphorus content <0.040%, sulfur content: <0.020%; low-manganese high-quality carbon scrap steel: carbon ≤0.5%, manganese <0.3%,

[0042] b. Smelting treatment process: the bottom coke height of the cupola furnace is 1800~2000mm, and the furnace material is smelted with Q10 pig iron and scrap steel with 500kg layer coke according to the following ratio, including 420kg of newborn iron, 80kg of scrap steel, and 50kg of coke; the chemistry of molten iron after smelting The ingredients are shown in Table 1; the furnace temperature is above 1450°C;

[0043]c. Spheroidization treatment: spheroidization is carried out by using the capping spheroidization method, and the rare earth magnesium alloy FeSiMg8Re3 is used in an amount of 1.5~1....

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Abstract

The invention discloses a method for preparing nodular cast iron. According to the invention, a cupola melting technology and an appropriate nodulizing process technology are adopted, inoculation is conducted for many times, and the box is opened in appropriate time, and therefore, that the high-quality low-temperature high-toughness nodular cast iron, of which the low-temperature comprehensive performance conforms to the QT400-18AL(-20 DEG C) standard is obtained is ensured. The nodular cast iron contains the following ingredients by weight percent: 3.3-3.6 percent of C, 1.8-2.2 percent of Si, less than 0.20 percent of Mn, 0.040 percent of P and Lt, 0.020 percent of S and Lt, 0.030-0.040 percent of Re and 0.040-0.055 percent of Mg. The nodular cast iron can meet the quality demands of low-temperature high-performance castings of wind power, nuclear power, high-speed rails and the like with higher quality requirements.

Description

technical field [0001] The invention relates to a preparation method of nodular cast iron, more specifically to a process method for manufacturing QT400-18AL nodular cast iron by smelting in a cupola furnace, which belongs to the field of casting technology. Background technique [0002] QT400-18AL nodular cast iron has been widely used in wind power, nuclear power and high-speed rail locomotive industries due to its high elongation and good impact toughness under low temperature conditions. At present, the smelting process of QT400-18AL ductile iron produced in my country is mainly based on electric furnace smelting, but very few are smelted by cupola furnace, and it is not suitable to meet its requirements for low temperature impact toughness, resulting in a high scrap rate. Contents of the invention [0003] The object of the present invention is just to provide a kind of process method of utilizing cupola smelting to manufacture QT400-18AL nodular cast iron aiming at t...

Claims

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Application Information

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IPC IPC(8): C21C1/10C22C33/08B22D1/00
CPCY02P10/20
Inventor 洪书淮陈献西余颂青
Owner CHTC HEAVY IND
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