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A method for preparing nodular cast iron

A technology of nodular cast iron and graphite, applied in the field of preparation of nodular cast iron, can solve the problems of low spheroidization level, uneven distribution of nodular graphite, and many intermediate treatment processes, and achieve the effect of overcoming strict control of process parameters.

Active Publication Date: 2011-12-07
HUAZHONG UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] The object of the present invention is to provide a method for preparing nodular cast iron, which avoids the characteristics of many intermediate treatment processes and strict control of process parameters in the above-mentioned traditional preparation process, and overcomes the low level of nodularization and the distribution of nodular graphite in the smelting process of nodular cast iron. uneven defect

Method used

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  • A method for preparing nodular cast iron
  • A method for preparing nodular cast iron
  • A method for preparing nodular cast iron

Examples

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Effect test

example 1

[0034] Example 1: Using a MIG welding machine to prepare high-nickel nodular cast iron with graphite balls of grade 6 (GB9441-88)

[0035] Make welding wire according to each composition and proportioning in Table 1; Wherein carbon selects and passes through 400 mesh sieve graphite, adopts the MIG welding machine that has argon gas protection, the welding wire is smelted, and its process parameter is: at 12 liters / minute argon gas Under a protective atmosphere, set the welding voltage to 30 volts, the current to 300 amperes, the wire feeding speed to 35 m / h, the melting diameter of the welding wire to be 2.0 mm, and cool down.

[0036] After cooling the material, the photo obtained by metallographic observation is as follows: figure 1 As shown, according to the spheroidization classification of graphite (GB9941-88), the graphite spheroidization grade and graphite diameter classification in the present invention are 6 grades, and the mechanical properties obtained by the test a...

example 2

[0041] Example 2: Preparation of nodular cast iron with grade 8 graphite balls by smelting with plasma arc heat source

[0042] (1) Selection of raw materials: 200-mesh iron powder and 4000-mesh graphite powder are mixed evenly in a mass ratio of 16:4, and dried.

[0043] (2) Using plasma transfer arc heat source for smelting, set the parameters as follows: under the protection of 12 liters / minute of argon atmosphere, set the voltage to 32V, the current to 350 amperes, and adopt the powder feeding speed of 5 grams / minute, the plasma Metallographic appearance obtained after cooling by body arc heat source melting figure 2 As shown, according to the spheroidization classification of graphite (GB9941-88), the graphite spheroidization grade and graphite diameter classification in the present invention are 8 grades.

example 3

[0044] Example 3: Preparation of nodular cast iron with grade 8 graphite balls by laser beam heat source smelting

[0045] Mix 200-mesh iron powder and 4000-mesh graphite powder evenly in a mass ratio of 16:4, dry them and send them to the processing chamber. In a vacuum environment, use a scanning speed of 2.5 mm / s and a laser power of 1 kilowatt to melt the raw materials. , after cooling, nodular cast iron is obtained, such as image 3 shown.

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Abstract

The invention discloses a method for preparing nodular cast iron, which comprises the following steps: firstly determining chemical components and a mass ratio of each chemical component according the components and a mass ratio of each component of the nodular cast iron to be prepared so as to obtain raw materials, wherein the carbon element in the used raw materials is in a form of granular graphite, and the dimension grade equals the dimension grade of the graphite in the nodular cast iron to be prepared; then melting the raw materials in the presence of a protective medium or in vacuum environment, and cooling to obtain the nodular cast iron. The invention avoids the characteristics of excessive intermediate treatment processes and strict process parameter control in traditional preparation processes, overcomes the defects of low nodulizing grade and non-uniform spheroidal graphite distribution in melting processes of nodular cast iron, reaches nodularity of above 90%, and obtainsa nodular cast iron material with uniform distribution.

Description

technical field [0001] The invention relates to a preparation method of nodular cast iron, in particular to a method for preparing nodular cast iron by melting heat sources of energy beams (such as laser beams, electron beams, plasma beams, welding arcs). Background technique [0002] Ductile iron has good mechanical properties because its carbon is spherical in cast iron, so it is widely used. [0003] The traditional ductile iron smelting preparation process is as follows: [0004] 1. Select raw materials according to the chemical composition of ductile iron and the mass ratio of each component. General raw materials include pig iron, steel scrap, coke, desulfurizer, nodulizer, recarburizer, pretreatment agent, etc. [0005] 2. Material smelting, the specific smelting process is as follows: [0006] 1) The main raw materials are melted to obtain molten iron, including pig iron, waste low-carbon steel, etc. [0007] 2) Pretreatment, the specific method is to improve the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C1/10C22C33/08
Inventor 张海鸥胡双锋王桂兰
Owner HUAZHONG UNIV OF SCI & TECH
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