Method for improving structure homogeneity and performance of large-section nodular cast iron

A technology for ductile cast iron with uniform structure, which is applied in the field of structure uniformity and performance of ferrite-based ductile iron castings for low-temperature and high-toughness wind power. It can solve the problems of limited inoculation effect, increase the number of graphite balls per unit area, and improve the structure Uniformity, improvement of structure, and improvement of graphite grade

Active Publication Date: 2015-02-04
JIANGSU HONGDE SPECIAL PARTS CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Purpose of the invention: In order to overcome the problems in the background technology, the present invention provides a method for improving the structure uniformity and performance of large-section nodular cast iron: by adopting furnace pretreatment + bottom inoculation + tapping inoculation + flow inoculation The matching treatment method solves the problem of limited inoculation effect of traditional inoculation methods and increases the number of graphite balls per unit area of ​​large cross-section; at the same time, the segregation of RE elements is partially neutralized by adding trace element Sb, which improves the ring-shaped "weak zone" The microstructure improves the microstructure uniformity of the large section of ductile iron and improves the quality of the entire section; in addition, the present invention uses the microstructure and performance of the worst position and the central position as parameters to measure the performance level of large section ductile iron

Method used

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  • Method for improving structure homogeneity and performance of large-section nodular cast iron
  • Method for improving structure homogeneity and performance of large-section nodular cast iron
  • Method for improving structure homogeneity and performance of large-section nodular cast iron

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Embodiment 1

[0043] A method for improving microstructure uniformity and performance of large-section ductile iron, involving large-section ductile iron, the components of which are: C content 3.80%, Si content 2.0%, Mn content 0.126%, P The content is 0.022%, the S content is 0.017%, the Sb content is 50ppm, and the rest is Fe and unavoidable trace elements;

[0044] The method for improving structure uniformity and performance of large-section ductile iron comprises the following steps:

[0045] (1) Melting

[0046] A. Select the charge, which includes pig iron (30%), scrap steel (30%), and returned charge (40%);

[0047]B. Add a pretreatment agent accounting for 0.15% of the weight of molten iron to be released, and add it together with the charge;

[0048] C. After the furnace material is melted, remove the slag and take the sample in front of the furnace, detect the content of C, Si, Mn, P, S, adjust C and Si and desulfurize. The final composition in the furnace is: C: 3.80%, Si: 1...

Embodiment 2

[0068] A method for improving the structure uniformity and performance of large-section ductile iron, involving large-section ductile iron, the components of which are: C content 3.83%, Si content 2.09%, Mn content 0.127%, P The content is 0.021%, the S content is 0.018%, the Sb content is 80ppm, and the rest is Fe and unavoidable trace elements;

[0069] The method for improving structure uniformity and performance of large-section ductile iron comprises the following steps:

[0070] (1) Melting

[0071] A. Select the charge, which includes pig iron (30%), scrap steel (25%), and returned charge (45%);

[0072] B. Add a pretreatment agent accounting for 0.17% of the weight of molten iron to be released, and add it together with the charge;

[0073] C. After the furnace material is melted, remove the slag and take a sample before the furnace, detect the content of C, Si, Mn, P, and S, adjust C and Si and desulfurize. The final composition in the furnace is: C: 3.83%, Si: 1.1...

Embodiment 3

[0093] A method for improving microstructure uniformity and performance of large-section ductile iron, involving large-section ductile iron, the components of which are as follows in terms of mass percentage: C content is 3.85%, Si content is 2.2%, Mn content is 0.133%, P The content is 0.021%, the S content is 0.014%, the Sb content is 100ppm, and the rest is Fe and unavoidable trace elements;

[0094] The method for improving structure uniformity and performance of large-section ductile iron comprises the following steps:

[0095] (1) Melting

[0096] A. Select the furnace charge, which includes pig iron (35%), scrap steel (30%), and recycled charge (35%);

[0097] B. Add a pretreatment agent accounting for 0.2% of the weight of molten iron to be released, and add it together with the charge;

[0098] C. After the furnace material is melted, remove the slag and take the sample in front of the furnace, detect the content of C, Si, Mn, P, S, adjust C and Si and desulfurize. ...

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Abstract

The invention discloses a method for improving structure homogeneity and performance of large-section nodular cast iron, which reveals that in large-section ferrite-based nodular cast iron, a position where a graphite nodule is not round and normal, large in size and worst in performance is not in the center where the coagulation time of a large-section cast piece is longest but in a nearly-annular region which is 20mm-40mm away from the outer edge of a large-section nodular cast iron piece. According to the method, reasonable chemical components, and high-quality nodulizing agent and nucleating agent are selected, a proper amount of a trace element Sb is added, a composite nucleation mode of bottom-coated nucleation, iron discharging nucleation and metal-stream nucleation is adopted, a structure of the large-section nodular cast iron in this region is improved, the structure homogeneity and performance of the large-section nodular cast iron are improved, and a low-temperature high-toughness large-section ferrite-based nodular cast iron piece is obtained; the low-temperature high-toughness large-section ferrite-based nodular cast iron piece is excellent in impact resistance and good in tensile property under -20 DEG C and -40 DEG C; and the technical problems that the large-section nodular cast iron piece is easy to be inhomogeneous in structure and bad in strength and low-temperature impact toughness comprehensive performance are solved.

Description

technical field [0001] The invention relates to a method for improving the structure uniformity and performance of large-section ductile iron, in particular to a method for improving the structure uniformity and performance of ferrite-based ductile iron castings with a wall thickness ≥ 300mm for low-temperature and high-toughness wind power. Background technique [0002] Ferrite-based nodular cast iron is widely used in the production of key wind power components because of its good low-temperature impact toughness and tensile strength. However, as the power of wind power equipment continues to increase, the size of key components is getting larger and larger, which brings new problems to the development of ferrite-based ductile iron. [0003] Due to the slow solidification speed of the center part of large-section ferrite-based ductile iron, structural defects such as distorted graphite, shrinkage porosity, and shrinkage cavity often occur in the central part: during the so...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C1/10C22C33/08C22C37/10B22D1/00
CPCY02P10/20
Inventor 杨金德潘冶陈琳许玉松陈立新曹培新
Owner JIANGSU HONGDE SPECIAL PARTS CO LTD
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