阅读说明：本技术 一种使过共晶铝硅合金共晶凝固离异化的方法 (Method for separating hypereutectic aluminum-silicon alloy from dissimilarity during eutectic solidification ) 是由 廖恒成 郑基伟 钱龙杰 陈浩 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种使过共晶铝硅合金共晶凝固离异化的方法,首先通过电阻坩埚炉对过共晶铝硅合金进行熔炼,采用热电偶和可控硅温控仪对熔体进行控温,熔清后进行除气去渣精炼处理。随后进行熔体处理：对电阻坩埚炉进行断电炉冷,接近设定温度580-720℃时通电调整电炉功率系数进行保温10-60min,采用玻璃管吸液随后在空气中冷却凝固方法制造合金试样。本发明对过共晶铝硅合金中出现的初生硅相有很好的细化效果,初生硅颗粒尺寸细小、分布均匀；与常规铸造相比,本发明可使共晶凝固过程离异化,将常规铸造中出现的片状共晶硅相颗粒化,为提高过共晶铝硅合金塑性提供一种新的工艺思路；本发明不会在熔体中引入杂质,操作成本低,不会对环境造成污染。(The invention discloses a method for solidifying and separating hypereutectic aluminum-silicon alloy eutectic, which comprises the steps of smelting hypereutectic aluminum-silicon alloy through a resistance crucible furnace, controlling the temperature of a melt by adopting a thermocouple and a silicon controlled temperature controller, and degassing, deslagging and refining after the melt is clear. Subsequently, melt processing is carried out: and (3) powering off the resistance crucible furnace, cooling the resistance crucible furnace, electrifying when the temperature is close to the set temperature of 580-720 ℃, adjusting the power coefficient of the electric furnace, carrying out heat preservation for 10-60min, absorbing liquid by using a glass tube, and then cooling and solidifying in the air to manufacture an alloy sample. The invention has good refining effect on the primary silicon phase appearing in the hypereutectic aluminum-silicon alloy, and the primary silicon particles have small size and uniform distribution; compared with the conventional casting, the method can separate the eutectic solidification process, granulate the flaky eutectic silicon phase in the conventional casting, and provide a new process idea for improving the plasticity of the hypereutectic aluminum-silicon alloy; the invention can not introduce impurities into the melt, has low operation cost and can not cause pollution to the environment.)

1. A method for separating the eutectic solidification of a hypereutectic aluminum-silicon alloy, comprising the steps of:

(1) placing the hypereutectic aluminum-silicon alloy raw material into a resistance crucible furnace, heating to 600-650 ℃, and then preserving heat;

(2) heating the raw materials obtained in the step (1) to 750-780 ℃ for melting, and preserving heat after melting down;

(3) cooling the alloy melt obtained in the step (2) to 720-730 ℃ in a furnace, and performing degassing, deslagging and purifying treatment;

(4) continuing to preserve the heat of the alloy melt obtained in the step (3) at 720-730 ℃, then cooling, and controlling the temperature to be preserved at 580-720 +/-2 ℃;

(5) and (4) preparing an alloy sample by a method of imbibing the alloy melt obtained in the step (4) and cooling and solidifying in air.

2. The method for separating the eutectic solidification of the hypereutectic aluminum-silicon alloy according to claim 1, wherein in the step (1), the hypereutectic aluminum-silicon alloy raw material is preheated at 300 ℃ of 250 ℃ for 30-35min and then placed in the resistance crucible furnace.

3. The method for eutectic solidification and segregation of hypereutectic aluminum silicon alloys according to claim 1, wherein in step (1), the holding time is 10-15 min.

4. The method for eutectic solidification and segregation of hypereutectic aluminum-silicon alloys according to claim 1, wherein in step (2), the temperature is maintained for 30-60min after melting down.

5. The method for eutectic solidification and segregation of hypereutectic aluminum-silicon alloys according to claim 1, wherein in step (4), the alloy melt obtained in step (3) is kept at 720-730 ℃ for 30-60 min.

6. The method for eutectic solidification and segregation of hypereutectic aluminum-silicon alloy as claimed in claim 1, wherein in the step (4), the temperature is controlled within 580-.

7. A method of eutectic solidification and segregation of hypereutectic aluminum silicon alloys according to claim 1, wherein in step (5) said liquid absorption is performed through a glass tube.

8. The method for eutectic solidification and segregation of hypereutectic aluminum silicon alloys according to claim 7, wherein in step (5), the inner diameter of the glass tube is 8-12 mm.

9. The method for dissociating the eutectic solidification of a hypereutectic aluminum-silicon alloy according to claim 1, wherein in step (1), the power of the electric resistance crucible furnace is 5-100 kW.

Technical Field

The invention belongs to the technical field of metal casting, and particularly relates to a method for separating hypereutectic aluminum-silicon alloy eutectic solidification.

Background

The hypereutectic aluminum-silicon alloy has the advantages of excellent wear resistance, low thermal expansion performance, good volume stability and the like, so that the hypereutectic aluminum-silicon alloy becomes an ideal material for manufacturing key parts such as automobile internal combustion engine pistons and the like. However, the hypereutectic aluminum-silicon alloy has a significant disadvantage, and the presence of plate-shaped, five-petal star-shaped, octahedral and pyramid-shaped coarse primary silicon phases and sheet-shaped eutectic silicon formed in the cast hypereutectic aluminum-silicon alloy is easy to become a propagation channel of cracks, and becomes an important factor for limiting the improvement of the casting plasticity and toughness. The texture state seriously cracks the matrix, causes serious reduction of the plasticity of the casting, and causes limitation to the large popularization of hypereutectic aluminum-silicon alloy in the actual industrial production. In order to generalize the advantages of hypereutectic aluminum-silicon alloys themselves, it becomes important to reduce the size of primary and eutectic silicon phases, and to improve the morphology of primary and eutectic silicon and their distribution in microscopic structures.

At present, many researchers at home and abroad have conducted a lot of research on how to refine the primary silicon phase in hypereutectic aluminum-silicon alloy and change the morphology of the eutectic silicon phase. The main methods for regulating and controlling the silicon phase include semi-solid treatment, modification treatment, melt treatment, rapid solidification and the like. These methods are all capable of reducing the size of the primary silicon phase to some extent in refining the primary silicon phase, especially the rapid solidification method. However, some of the methods have high production cost and complex preparation process, and particularly the eutectic solidification process is not dissociated, so that the mechanical properties are not obviously broken through.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a method for separating the eutectic solidification and dissimilation of hypereutectic aluminum-silicon alloy, which completely separates the eutectic solidification process, ensures that the size of the silicon phase particles after the dissimilation is less than 20 mu m, has round appearance and uniform distribution, and is not sharp any more.

The technical scheme is as follows: the invention relates to a method for separating eutectic solidification of hypereutectic aluminum-silicon alloy, which comprises the following steps:

(1) placing the hypereutectic aluminum-silicon alloy raw material into a resistance crucible furnace, heating to 600-650 ℃, and then preserving heat;

(2) heating the raw materials obtained in the step (1) to 750-780 ℃ for melting, and preserving heat after melting down;

(3) cooling the alloy melt obtained in the step (2) to 720-730 ℃ in a furnace, and performing degassing, deslagging and purifying treatment;

(4) continuing to preserve the heat of the alloy melt obtained in the step (3) at 720-730 ℃, then cooling, and controlling the temperature to be preserved within +/-2 ℃ of 580-720 ℃;

(5) and (4) preparing an alloy sample by a method of imbibing the alloy melt obtained in the step (4) and cooling and solidifying in air.

Further, in the step (1), the hypereutectic aluminum-silicon alloy raw material is preheated at the temperature of 250-300 ℃ for 30-35min and then placed in a resistance crucible furnace.

Further, in the step (1), the heat preservation time is 10-15 min.

Further, in the step (2), heat preservation is carried out for 30-60min after melting down.

Further, in the step (4), the alloy melt obtained in the step (3) is kept at 720-.

Further, in the step (4), the temperature is controlled within 580-.

Further, in the step (5), the liquid suction is performed through a glass tube.

Further, in the step (5), the inner diameter of the glass tube is 8-12 mm.

Further, in the step (1), the power of the resistance crucible furnace is 5-100 kW.

In the steps of the method, all materials and moulds in contact with the melt are preheated for more than 30 minutes at the preheating temperature of 250-300 ℃. Wherein all materials in contact with the melt include a strainer, a bell, a refining agent, and a mold used for casting.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:

(1) the invention discloses a method for separating eutectic solidification and dissimilation of hypereutectic aluminum-silicon alloy, which has good effect of inhibiting the eutectic solidification coupling growth commonly occurring in hypereutectic aluminum-silicon alloy, so that the eutectic solidification process is completely dissimilated, the size of the silicon phase particles after dissimilation is less than 20 mu m, the appearance becomes round and round, the edges and corners are not clear any more, and the distribution is uniform.

(2) The invention has no flaky eutectic silicon phase, and provides an ideal process design idea for improving the plasticity of the hypereutectic aluminum-silicon alloy.

(3) In the invention, no alterant is added in the operation process, so that the serious pollution of the past method for adding the alterant to the environment is avoided, other impurities cannot be introduced into the melt, and the operation cost is low.

Drawings

FIG. 1 shows the structure of a hypereutectic Al-Si alloy obtained by taking samples of example 1, in which the melt was kept at 720 ℃ for 10 minutes and the glass tube was imbibed with liquid and then air-cooled (cooled and solidified in air);

FIG. 2 shows the structure of a hypereutectic Al-Si alloy obtained by holding the melt at 650 ℃ for 10 minutes, imbibing the glass tube and then sampling the melt by air cooling in example 2;

FIG. 3 shows the structure of a hypereutectic Al-Si alloy obtained by holding the melt at 580 ℃ for 10 minutes, imbibing the glass tube and then sampling the melt by air cooling in example 3;

FIG. 4 shows the structure of a hypereutectic Al-Si alloy obtained by direct liquid suction through a glass tube and subsequent air cooling sampling of the melt at 650 ℃ in example 4;

FIG. 5 shows the structure of a hypereutectic Al-Si alloy obtained by holding the melt at 650 ℃ for 60 minutes, imbibing the glass tube and then sampling the melt by air cooling in example 5;

FIG. 6 shows the structure of a hypereutectic Al-Si alloy obtained in a metal mold obtained by direct casting of the melt at 720 ℃ in example 6;

FIG. 7 shows the structure of a hypereutectic Al-Si alloy obtained by casting the melt of example 7 at 650 ℃ for 10 minutes in a metal mold.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

By taking Al-16Si-4.2Cu-0.6Mg-0.8Fe alloy as an example (the protection scope of the invention is not limited to the alloy), the substantial connotation and the obvious effect of refining the primary silicon by the method are clarified by different examples.

Example 1

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the heat of the alloy melt obtained in the step (3) for 30 minutes at 720 ℃, and controlling the temperature within 720 +/-2 ℃ for 10 minutes by adjusting the power coefficient of an electric furnace.

(5) And (4) sucking the alloy melt obtained in the step (4) through a glass tube, and then sampling in an air cooling mode to obtain the structural state of the alloy. The solidification microstructure is shown in figure 1, the diameter value of primary silicon is 10-20 μm, the appearance is round and uniform, the eutectic solidification is completely separated, and no flaky eutectic silicon phase exists.

Example 2

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the heat of the alloy melt obtained in the step (3) for 30 minutes at 720 ℃, then cooling, and controlling the temperature to be 650 +/-2 ℃ for 10 minutes by adjusting the power coefficient of the electric furnace in the cooling process.

(5) And (4) sucking the alloy melt obtained in the step (4) through a glass tube, and then sampling in an air cooling mode to obtain the structural state of the alloy. The solidification microstructure is shown in figure 2, the diameter value of primary silicon is 10-20 μm, the appearance is round and uniform, the eutectic solidification is completely separated from dissimilation, and no flaky eutectic silicon phase exists.

Example 3

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the heat of the alloy melt obtained in the step (3) for 30 minutes at 720 ℃, then cooling, and controlling the temperature to be preserved for 10 minutes at 580 +/-2 ℃ by adjusting the power coefficient of the electric furnace in the cooling process.

(5) And (4) sucking the alloy melt obtained in the step (4) through a glass tube, and then sampling in an air cooling mode to obtain the structural state of the alloy. The solidification microstructure is shown in figure 3, the diameter value of primary silicon is 10-20 μm, the appearance is round and uniform, the eutectic solidification is completely separated, and no flaky eutectic silicon phase exists.

Example 4

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the heat of the alloy melt obtained in the step (3) for 30 minutes at 720 ℃, then cooling, and controlling the temperature to be preserved for 0 minute at 650 +/-2 ℃ by adjusting the power coefficient of the electric furnace in the cooling process.

(5) And (4) sucking the alloy melt obtained in the step (4) through a glass tube, and then sampling in an air cooling mode to obtain the structural state of the alloy. The solidification microstructure is shown in figure 4, the diameter value of primary silicon is 10-20 μm, the appearance is round and uniform, the eutectic solidification is completely separated, and no flaky eutectic silicon phase exists.

Example 5

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the heat of the alloy melt obtained in the step (3) for 30 minutes at 720 ℃, then cooling, and controlling the temperature to be 650 +/-2 ℃ for 60 minutes by adjusting the power coefficient of the electric furnace in the cooling process.

(5) And (4) sucking the alloy melt obtained in the step (4) through a glass tube, and then sampling in an air cooling mode to obtain the structural state of the alloy. The solidification microstructure is shown in figure 5, the diameter value of primary silicon is 10-20 μm, the appearance is round and uniform, the eutectic solidification is completely separated, and no flaky eutectic silicon phase exists.

Example 6

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the temperature of the alloy melt obtained in the step (3) at 720 ℃ for 30 minutes.

(5) And (4) directly pouring the alloy melt obtained in the step (4) into a metal mold, and cooling to obtain a structure state. The solidification microstructure is shown in figure 6, the diameter value of primary silicon is about 100 mu m, the appearance is sharp, the eutectic solidification is completely coupled to grow, and a plurality of coarse flaky eutectic silicon phases exist.

Example 7

(1) All materials and molds in contact with the melt need to be preheated for more than 30 minutes at the preheating temperature of 250 ℃. The hypereutectic aluminum-silicon alloy raw material is put into a resistance crucible furnace and heated to 600 ℃.

(2) Heating the raw materials obtained in the step (1) to 760 ℃ for melting, and preserving heat for 30 minutes after melting down.

(3) And (3) cooling the alloy melt obtained in the step (2) to 720 ℃ in a furnace, and carrying out degassing, deslagging and purifying treatment.

(4) And (4) preserving the temperature of the alloy melt obtained in the step (3) at 720 ℃ for 30 minutes. And then cooling, wherein the temperature is controlled within 650 +/-2 ℃ for 10 minutes by adjusting the power coefficient of the electric furnace in the cooling process.

(5) And (4) directly pouring the alloy melt obtained in the step (4) into a metal mold, and cooling to obtain a structure state. The solidification microstructure is shown in figure 7, the diameter value of primary silicon is about 100 mu m, the appearance is sharp, eutectic solidification is completely coupled to grow, and a plurality of coarse flaky eutectic silicon phases exist.

Comparative analysis of examples 1-7:

the method for solidifying and dissimilating the hypereutectic aluminum-silicon alloy eutectic can obtain better effect of refining silicon phase, eliminate common flaky eutectic silicon phase in the structure, completely dissociate the eutectic solidification, and provide an ideal process thought for improving the plasticity of the hypereutectic aluminum-silicon alloy. Examples 1 to 5 the microstructure of the alloy was obtained by direct glass tube sampling followed by air cooling after melt processing, and examples 6 and 7 were cast at a set temperature using a conventional casting and casting process, and it was found that: in the figures 1 to 5, the size of the silicon phase is obviously smaller and is within 20 mu m, the primary silicon phase becomes passivated and rounded, the whole distribution is uniform, the eutectic solidification can be completely separated from the dissimilarity, and the flaky eutectic silicon phase in the structure completely disappears. Examples 6 and 7, which employ a method of performing metal mold casting after melt processing, have found that the size of primary silicon particles is about 100 μm, the refining effect is not as good as that of fig. 1 to 5, and the primary silicon particles are not rounded and contain coarse flaky eutectic silicon phases. Therefore, in summary, the method for solidifying and dissimilating the hypereutectic aluminum-silicon alloy eutectic can achieve good refining effect, the silicon particles are small in size and uniform in distribution, the separation of flaky eutectic silicon in conventional casting can be eliminated, and an ideal process thought is provided for improving the plasticity of the hypereutectic aluminum-silicon alloy. In addition, the operation cost is low, impurities cannot be introduced in the production process, and the environment cannot be polluted.