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Processing method for improving cast iron solidified structure

A processing method and technology for solidification structure, applied in the field of processing to improve the solidification structure of cast iron, can solve the problems of unsatisfactory effect of temperature field and composition homogenization, insignificant refinement effect, and metal liquid pollution, etc., and achieve solidification. The organization is obvious, the process operation is simple and convenient, and the effect of saving energy

Inactive Publication Date: 2007-04-11
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, compared with the common solidification method, this method does not significantly change the nucleation rate of crystal nuclei, so the refinement effect is not obvious
Secondly, strong stirring makes the molten metal turn up and down, which is also easy to get involved in air and other oxidized inclusions, which will inevitably pollute the molten metal
Furthermore, the stirring is limited by its stirring intensity, and the effect on the homogenization of the temperature field and components is not ideal.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0006] Embodiment 1: Sand casting molten iron into a cylindrical iron rod of φ50×200 mm. After pouring, it is treated with pulse current during the solidification process of the molten iron until the solidification of the molten iron is completed.

[0007] The composition and content (percentage by weight) of cast iron are: C 4.10%, Si 1.92%, Mn 0.22%, P0.058%, S 0.023%, Fe balance, and the temperature for starting molten iron treatment is 1250°C. When the temperature is 1000°C, the power-on treatment is stopped; the process parameters are as follows: the pulse frequency is 0.8Hz, the output voltage U is 2000V, and the current intensity I is 30000A.

Embodiment 2

[0008] Embodiment 2: The test process is exactly the same as that of Embodiment 1, and the chemical composition and content (percentage by weight) of the cast iron are also the same. However, different process parameters are adopted, the process parameters are: pulse frequency 1000Hz, output voltage U 50V, current intensity I 800A.

Embodiment 3

[0009] Embodiment three: test process is exactly the same as embodiment one, and the composition and content (percentage by weight) of cast iron are: C 3.58%, Si 1.60%, Mn 0.18%, P 0.045%, S 0.020%, Fe surplus, molten iron The temperature at which the treatment starts is 1250°C, and when the temperature drops to 1000°C, the power-on treatment is stopped; the process parameters are as follows: pulse frequency 0.1Hz, output voltage U 5000V, and current intensity I 100000A.

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Abstract

The treating method for improving cast iron solidifying structure features that before or during solidification of grey cast iron with carbon equivalent of 2.5-5.0 %, pulse current is introduced and the cast iron has initial treating temperature of 1200-1500 deg.C and final treating temperature of 1000 deg.C. The pulse current parameters include pulse frequency of 0.1-10000 Hz, pulse voltage of 50-5000 V, and pulse peak current 400-100,000 A. The electric treatment may be completed in the crucible, the pouring ladle or the casting mold.

Description

technical field [0001] The invention relates to a treatment method for improving the solidification structure of cast iron, which belongs to the technical field of thermal processing of metal materials. Background technique [0002] In order to change the solidification structure of cast iron, obtain evenly refined graphite, and prevent white spots in cast iron, there are currently three main measures taken in the production process of castings or slabs at home and abroad: one is chemical methods, that is, before the cast iron solidifies Chemical substances such as ferrosilicon, rare earth or magnesium are added to the molten iron to achieve the purpose of inoculation treatment, spheroidization treatment or vermicomposting treatment, so that cast iron can avoid white spots, precipitate graphite evenly and finely, or change the shape of graphite to make graphite spherical or worm-like. These substances achieve the purpose of changing the morphology of graphite by changing th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D27/02
Inventor 翟启杰范金辉陈宇富知愚华勤李仁兴侯旭李祖齐
Owner SHANGHAI UNIV