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Ferrite ductile iron used at low temperature and manufacturing method thereof

A manufacturing method and ferrite technology, applied in the direction of process efficiency improvement, etc., can solve problems such as difficulty in reaching the standard stably, lack of sufficient attention to the importance of chemical components, etc., and achieve stable sources, intuitive chemical composition range, and fine graphite balls. Effect

Active Publication Date: 2012-08-15
ZHENGZHOU RES INST OF MECHANICAL ENG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Analyzing the reasons, on the one hand, there is insufficient attention to the importance of chemical composition; on the other hand, even if the chemical composition range of ductile iron is stipulated, it is difficult to meet the standard stably according to the current supply of pig iron and scrap steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] The raw materials are selected according to the following weight ratio: YT2 pure iron 93.5%, graphite recarburizer 4.0%, TFeSi75-A ferrosilicon 1.5%;

[0048] Put 20% of the above-mentioned pure iron raw material at the bottom of the electric furnace, heat and melt it, then add the ferrosilicon raw material baked at 200°C, and then add the remaining pure iron and 80% of the carburizer into the furnace one after another. After melting, heat the molten iron to 1450°C, heat preservation, sampling, and spectral composition analysis before the furnace; then add the remaining recarburizer on the surface of the molten iron, continue to heat up to 1500-1520°C, sample, and analyze the spectral composition before the furnace. After the composition of the molten iron is qualified, it will be released at 1460-1500°C (choose according to the pouring temperature of the casting).

[0049] The following table is the chemical composition measurement results of the above molten iron:

...

Embodiment 2

[0053] The chemical composition (by mass percentage) of the cast ferrite ductile iron for low temperature in the present invention is: C3.6-3.9%, Si2.2-2.4%, Mn<0.2%, P<0.02%, S<0.02% , Ti<0.04%, Mg residual 0.030-0.045%, Re residual 0.005-0.015%, and the rest is Fe.

[0054] Its manufacturing method is:

[0055] 1. Select raw materials according to the following weight ratio: YT2 pure iron 91.2%, graphite recarburizer 4.0%, TFeSi75-A ferrosilicon 1.5%;

[0056] 2. Put 20% of the above-mentioned pure iron raw material at the bottom of the electric furnace, heat and melt it, then add the ferrosilicon raw material baked at 200°C, and then add the remaining pure iron and 80% carburizer into the furnace one after another , after all melting, heat the molten iron to 1450°C, heat preservation, sampling, and spectral composition analysis before the furnace; then add the remaining recarburizer on the surface of the molten iron, continue to heat up to 1500-1520°C, take samples, and an...

Embodiment 3

[0065] Select raw materials according to the following weight percentage ratio: YT3 pure iron 91.2%, graphite recarburizer 4.0%, TFeSi75-A ferrosilicon 1.5%;

[0066] The smelting method is the same as in Example 2, wherein the dosage of nodulizer is 1.2%, and the dosage of inoculant is 1.1%. The casting can be poured after the nodularization treatment, and the time from the nodularization treatment to the completion of pouring is controlled within 6 minutes.

[0067] The following table shows the measurement results of the chemical composition of cast ferrite ductile iron:

[0068] 。

[0069] The impact test results of the ferrite ductile iron parts are as follows (Zhengzhou Haite Mold Co., Ltd., May 3, 2012, executive standard: ASTM E23; sample temperature: -40°C; sample size: 10*10*55 ):

[0070] Impact toughness 17.5 J / cm 2 ;Impact absorption energy 14.0 Ak (J); Cross-sectional area 0.8 cm 2 .

[0071] From Example 2 and Example 3, it can be seen that the ductile i...

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Abstract

The invention discloses chemical compositions of ferrite ductile iron used at low temperature and a manufacturing method of the ferrite ductile iron, determines the range of the chemical compositions of the ferrite ductile iron used at low temperature being minus 40 DEG C and provides a quality standard for the production of qualified and stable ductile iron workpieces. The manufacturing method comprises the steps of adopting pure iron, a carburant and silicon iron as raw materials, synthesizing and melting the raw materials in an electric furnace, conducting spheroidization on the raw materials by utilizing a low-rare-earth spheroidizing agent, and producing the ferrite ductile iron by adopting a combined inoculation method. According to the method, the purity of molten iron is improved stably, and the difficulties of high phosphorus, sulphur, titanium, other imputies and interference elements contents in the molten iron, large fluctuation and instability are solved. According to the method, a novel technical scheme is provided for the production of ferrite ductile iron workpiece which contains small, circular and smooth ductile iron and does not contain cementite and iron phosphide eutectic basically, the ferrite ductile iron can meet the demands of high-performance ferrite ductile iron workpiece in electrical industry, high-speed rail industry and the like, the dependence on imported products can be broken; and the running safety of nuclear power and the high-speed rail can be improved substantially.

Description

technical field [0001] The invention relates to the technical field of casting in the machinery industry, in particular to a ferrite nodular iron for low temperature of -40°C, and also relates to a method for manufacturing the nodular iron. Background technique [0002] Ductile iron (nodular iron) refers to the cast iron in which the graphite is spherical after the molten iron is treated with a nodularizer. The metallographic structure of ductile iron is composed of graphite balls and matrix structure. GB / T 9441-2009 "Metallographic Examination of Ductile Iron" divides graphite balls into 6 grades according to the degree of roundness. And toughness is good; graphite balls are divided into six grades according to size, reducing the diameter of graphite balls and increasing the number of graphite balls per unit area can significantly improve the strength, plasticity and toughness of ductile iron. The matrix structure of ductile iron mainly includes ferrite, pearlite, austenit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C37/10C22C33/08B22D1/00C21C1/10
CPCY02P10/20
Inventor 李克锐吴现龙李桐
Owner ZHENGZHOU RES INST OF MECHANICAL ENG CO LTD
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