Composite modification method for hypereutectic aluminum-silicon alloy

An aluminum-silicon alloy and compound modification technology, which is applied in the field of non-ferrous metal material preparation and forming, can solve the problems of poor fluidity, severe air absorption, increased pinhole and shrinkage tendency, etc., and achieves simple process, strong nucleation ability, and distributed uniform effect

Active Publication Date: 2013-10-23
CHINA NON-FERROUS METALS PROCESSING TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This is because too much Ca in the melt will lead to poor fluidity, severe gas absorption, increased tendency of pinholes and shrinkage porosity
Moreover, under the existing process conditions, when P and Ca co-exist in the melt, it is easy to react to form a Ca-P-Si compound that is more stable than the AlP core, and this compound does not have the effect of promoting heterogeneous nucleation
This not only weakens the modification effect of free Ca on eutectic silicon, but also makes P in the compound no longer have the effect of modifying primary silicon.

Method used

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  • Composite modification method for hypereutectic aluminum-silicon alloy
  • Composite modification method for hypereutectic aluminum-silicon alloy
  • Composite modification method for hypereutectic aluminum-silicon alloy

Examples

Experimental program
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Effect test

Embodiment 1

[0044] The selected hypereutectic Al-Si alloy composition is shown in Table 1. After the alloy is melted in a resistance furnace, the melt temperature is superheated to 820 o C. Use a bell jar to quickly press the preheated Cu-8P master alloy particles with an average particle size of about 1 mm into the melt. After fully dissolving and stirring evenly, keep the temperature for 20 min. Then, pour argon gas into the melt for degassing and refining for 15 minutes, and remove the surface scum. Then adjust the melt temperature to 760 o C, then add the preheated Al-Ca alloy thin rod with a diameter of φ6 mm into the melt, stir evenly, and keep it warm for 10 min. The content of P-Ca composite modifier in each batch of test melts is shown in Table 2. After compound metamorphism, at 740 o Under C, carry out semi-continuous casting to form a φ76mm cast rod. The statistical analysis of the modification effect of primary Si and eutectic Si in the microstructure of each batch of tes...

Embodiment 2

[0050] The selected hypereutectic Al-Si alloy composition is shown in Table 1. After the alloy is melted in the resistance furnace, adjust the melt temperature to overheat to 820 o C. Use a bell jar to quickly press the preheated Cu-8P master alloy particles with an average particle size of about 1 mm into the melt. After fully dissolving and stirring, keep warm for 5-240 min respectively. Then, pour argon gas into the melt for degassing and refining for 15 minutes, and remove the surface scum. Then adjust the melt temperature to 780 o C. Then add the preheated Al-Ca alloy thin rods with a diameter of φ10 mm into the melt, stir evenly, and keep warm for 10 to 180 minutes respectively. After the P-Ca compound metamorphism is completed, at 760 o C under semi-continuous casting forming φ76mm cast rod, cooling rate is 122 o C / s. The modification effects of primary Si and eutectic Si under different modification holding times are shown in Table 3.

[0051] Table 3 Modificatio...

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Abstract

The invention relates to a composite modification method for a hypereutectic aluminum-silicon alloy. According to the composite modification method, P and Ca are adopted for performing composite modification on the hypereutectic aluminum-silicon alloy, and a modification process comprises the following steps of: overheating a hypereutectic aluminum-silicon alloy melt to 760-850 DEG C, rapidly pressing a P modification agent into the melt, standing, performing heat preservation for 10-240min, degassing, refining, adjusting the temperature of the melt to 740-800 DEG C, adding a Ca modification agent into the melt, standing, performing heat preservation for 5-120min, and then molding by casting, wherein the casting temperature is controlled at 70-170 DEG C above a liquid phase line and the cooling speed is 10-1000 DEG C / s. According to the method, primary silicon in the hypereutectic aluminum-silicon alloy with the silicon content of 14-23% is refined to below 30mu m, the distribution is uniform, eutectic silicon is fibrous or dotted, and the mechanical properties are significantly improved.

Description

technical field [0001] The invention relates to a novel compound modification method for hypereutectic aluminum-silicon alloy, which belongs to the technical field of preparation and forming of nonferrous metal materials. Background technique [0002] Hypereutectic aluminum-silicon alloy has the advantages of good heat and wear resistance, low thermal expansion coefficient, good volume stability, and high specific strength. It is often used to manufacture wear-resistant and heat-resistant parts such as automotive engine pistons and automotive air-conditioning compressor swash plates. . The hypereutectic aluminum-silicon alloy prepared by the traditional process is prone to coarse plate-like primary silicon and needle-like eutectic silicon in the structure, which will severely split the matrix, significantly reduce the strength and toughness of the alloy, and deteriorate the machinability of the alloy. Therefore, the key to the preparation of high-performance hypereutectic A...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C21/04C22C1/06
Inventor 钟鼓长海博文吴志斌邱楚
Owner CHINA NON-FERROUS METALS PROCESSING TECH CO LTD
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