CN108118207B

CN108118207B - Cast aluminum-silicon alloy and preparation method thereof

Info

Publication number: CN108118207B
Application number: CN201711121186.6A
Authority: CN
Inventors: 周广顺
Original assignee: Beijing Shilian Xinnuo Technology Co ltd
Current assignee: Beijing Shilian Xinnuo Technology Co ltd
Priority date: 2017-11-14
Filing date: 2017-11-14
Publication date: 2020-05-08
Anticipated expiration: 2037-11-14
Also published as: CN108118207A

Abstract

A cast aluminum-silicon alloy comprises the following components in percentage by weight: 3.5-5.5%, Mg: 0.35-0.85%, Ti: 0.05-0.35%, Sb: 0.01-0.04%, Sc: 0.05-0.3%, less than or equal to 0.15% of impurities, and the balance of aluminum. The cast aluminum-silicon alloy has high strength, high elongation and good air tightness, can be widely applied to oil-way pipeline parts of various automobiles and engines, and has excellent comprehensive performance, so that the potential service life of the oil-way pipeline can be prolonged, and the safety is improved.

Description

Cast aluminum-silicon alloy and preparation method thereof

Technical Field

The application belongs to the field of metal materials, and relates to a high-quality and high-strength cast aluminum-silicon alloy and a preparation method thereof.

Background

Aluminum alloy is a common light metal material, and has been widely used in the industries of aviation, aerospace, automobiles, ships and the like. Particularly, the cast aluminum-silicon alloy has good fluidity and good mold filling capability, and has more compact internal structure compared with other cast aluminum alloys, so the cast aluminum-silicon alloy is widely applied to oil-way pipeline systems of engines, diesel engines and the like. However, the traditional cast aluminum-silicon alloy has high silicon content and is easy to combine with Na and K elements in the melt, so that the hydrogen absorption of the aluminum melt is serious; meanwhile, the use of certain high-strength and high-pressure oil-way pipelines is limited due to the high silicon content and poor alloy plasticity in the alloy.

Disclosure of Invention

In order to solve the problems, the application provides a casting aluminum-silicon alloy and a preparation method thereof.

The specific technical scheme is as follows:

a cast aluminum-silicon alloy, characterized in that:

the cast aluminum-silicon alloy comprises the following components in percentage by mass:

si: 3.5-5.5%, Mg: 0.35-0.85%, Ti: 0.05-0.35%, Sb: 0.01-0.04%, Sc: 0.05-0.3%, less than or equal to 0.15% of impurities and the balance of aluminum, wherein the mass percentage ratio of Ti to Sc is not higher than 1.2; the mass percentage ratio of Si to (Sc + Ti) is not less than 9.

Further, the content of Si is: 3.8 to 4.5% by mass.

Wherein, the content of Mg: 0.45 to 0.65 mass%.

Wherein the mass percent of Ti is as follows: 0.10 to 0.30 percent.

Wherein the Sb comprises the following components in percentage by mass: 0.02-0.03%.

Wherein the mass percent of Sc is as follows: 0.15 to 0.28 percent.

The application also discloses a preparation method of the cast aluminum-silicon alloy, which is characterized by comprising the following steps:

the first step is as follows: firstly, heating a smelting furnace to a preheating temperature for heat preservation, then adding aluminum, Si, Ti and Sc components according to mass percent, heating to be molten, overheating to 800-820 ℃, preserving heat for 2-3 h, and stirring for 10-15min after an aluminum ingot is molten;

the second step is that: cooling the melt to 700-710 ℃, adding Sb and Mg according to mass percent, and stirring for 3-5 min;

the third step: adding a refining agent accounting for 0.3-0.6% of the total melt mass of the cast aluminum-silicon alloy, stirring for 10-15min, and then performing inert gas blowing treatment;

the fourth step: and standing the sprayed alloy liquid for 20-30 min, and then pouring.

It is further preferable that the concentration of the organic compound,

in the first step, pure aluminum is used as the aluminum, and Si, Ti and Sc components are in the form of master alloy which comprises AlSi12, AlTi4 and AlSc2 (the content of elements in the master alloy meets the requirements of GB/T27677-.

In the second step, the Mg added is pure Mg; the added Sb is in the form of AlSb4 intermediate alloy (the element content in the intermediate alloy meets the requirements of GB/T27677-2011).

The application has the following beneficial technical effects:

1. on the basis of the traditional ZL114A aluminum-silicon alloy (refer to GB 1173-2013), the content of silicon element is greatly reduced, the hydrogen absorption tendency of alloy melt is reduced, and the internal compactness and air tightness of the alloy are improved;

2. the Sb element and the Sc element are simultaneously introduced into the aluminum-silicon alloy. The addition of Sb element can effectively improve the appearance and the size of primary silicon, and achieves the effects of appearance spheroidization and size refinement. The Sc element is added, so that the cast microstructure can be effectively refined, and the strength and the elongation of the alloy are improved.

After Sc element is introduced, Sc and Al are combined to precipitate fine Al in the subsequent T6 treatment (545 ℃ for 24h solution treatment and 160 ℃ for 8h aging treatment)₃The mass point of Sc is shown in the specification,the alloy strength is further improved;

3. the application can achieve the following technical indexes: the tensile yield strength can reach 350-370 MPa, the yield strength can reach 280-300 MPa, and the elongation is 12-14%. Air tightness performance: maintaining the pressure at 15MPa for 30min when the wall thickness of the casting is 3mm, wherein the value of a helium suction gun detector is not more than 10^-7Pa m³/s。

Drawings

FIG. 1 is a comparison of mechanical properties of the alloy of the present invention and ZL114A alloy after the same heat treatment;

FIG. 2 is a metallographic microstructure of an alloy according to the invention.

Detailed Description

The technical solution of the present application will be further described in detail with reference to the drawings and specific embodiments.

In the following examples, the components of the aluminum alloy were measured according to the national standard GB/T6987-.

Example 1

The present embodiment 1 discloses a high-quality, high-strength cast aluminum-silicon alloy, which comprises the following components by mass: si: 3.9%, Mg: 0.53%, Ti: 0.2%, Sb: 0.025%, Sc: 0.18 percent, 0.1 percent of impurities and the balance of aluminum.

The preparation method of the cast aluminum-silicon alloy containing the components comprises the following steps:

step 1: firstly heating a smelting furnace to 300-400 ℃, preserving heat for 20min, then adding pure aluminum, AlSi12, AlTi4 and AlSc2 intermediate alloy according to the proportion for smelting (the element content in the intermediate alloy meets the requirement of GB/T27677-;

step 2: reducing the temperature of the aluminum melt to 705 ℃, adding AlSb4 alloy (the content of elements in the master alloy meets the requirements of GB/T27677-2011) and pure Mg, and stirring for 5 min;

and step 3: adding a refining agent accounting for 0.5 percent of the total mass of the aluminum melt for refining, and stirring for 15 min; then, using inert gas to perform blowing treatment on the aluminum melt;

and 4, step 4: and standing the sprayed alloy liquid for 25min, and then pouring to obtain the alloy.

The alloy is kept warm for 24h at 540 ℃, water quenched at room temperature and kept warm for 8h at 160 ℃. The obtained aluminum alloy has the tensile strength of 353MPa, the yield strength of 286MPa and the elongation of 13.5 percent. Maintaining the pressure of the casting (average wall thickness of 2.8mm) at 15MPa for 30min, wherein the helium leakage detection value is 3 multiplied by 10^-9Pa m³/s。

Table 1 and fig. 1 show the comparison of the mechanical properties of the alloy treated by T6 and ZL114A, and it can be seen that the strength and elongation of the alloy of the present invention are significantly improved compared with ZL 114A.

Silicon in the aluminum melt is easy to combine with alkali metal elements (Na, K and the like) to cause hydrogen absorption, which can cause the hydrogen content in the melt to increase and influence the compactness, the strength and the elongation of the internal structure of the alloy. Therefore, the content of the silicon element is properly reduced, and the hydrogen absorption inclined phase is reduced. Meanwhile, a modifying element Sb and a strengthening element Sc are introduced to refine and spheroidize the primary silicon phase, and simultaneously, the microstructure of the alloy is further refined, so that the aims of high strength and high air tightness are fulfilled. In addition, in the subsequent heat treatment process, Sc element is combined with Ti element, and dispersed, fine and coherent Al is precipitated in the aluminum matrix₃And (Sc, Ti) phase, which improves the overall strength of the alloy.

TABLE 1 mechanical properties of the alloy of the present application after T6 treatment compared to ZL114A alloy

Example 2

The application relates to a high-quality and high-strength cast aluminum-silicon alloy which comprises the following components in percentage by mass: si: 4.2%, Mg: 0.62%, Ti: 0.23%, Sb: 0.028%, Sc: 0.20 percent, 0.13 percent of impurities and the balance of aluminum.

step 1: firstly heating a smelting furnace to 300-400 ℃, preserving heat for 15min, then adding pure aluminum, AlSi12, AlTi4 and AlSc2 intermediate alloy according to the proportion for smelting (the element content in the intermediate alloy meets the requirement of GB/T27677-;

step 2: reducing the temperature of the aluminum melt to 710 ℃, adding AlSb4 intermediate alloy (the content of elements in the intermediate alloy meets the requirements of GB/T27677-2011) and pure Mg, and stirring for 5 min;

and step 3: adding a refining agent accounting for 0.45 percent of the total mass of the aluminum melt for refining, and stirring for 20 min; then, using inert gas to perform blowing treatment on the aluminum melt;

and 4, step 4: and standing the sprayed alloy liquid for 15min, and then pouring to obtain the alloy.

The alloy is kept warm for 24h at 540 ℃, water quenched at room temperature and kept warm for 8h at 160 ℃. The obtained aluminum alloy has the tensile strength of 360MPa, the yield strength of 292MPa and the elongation of 12.3 percent. Maintaining the pressure of the casting (average wall thickness of 2.8mm) at 15MPa for 30min, and detecting the helium leakage value to be 6 multiplied by 10^-8Pa m³/s。

TABLE 2 mechanical properties of the alloy of the present application after T6 treatment compared to ZL114A alloy

Since the alloy of example 2 had slightly higher Si and Sc elements than example 1, the number of strengthening phases precipitated in the matrix was large in the same heat treatment state (eutectic silicon and secondary Al)₃(Sc, Ti)), the strength was slightly higher than in example 1, but the elongation was slightly decreased.

FIG. 2 is a photograph showing the microstructure of the alloy of example 2. It can be seen that primary Si of the Al-Si alloy is fine and is mostly spherical, which indicates that Sc and Sb are simultaneously added into Al-Si, which is beneficial to spheroidizing of eutectic Si structure, and is the main reason for obviously improving the elongation of the alloy compared with the traditional ZL114A alloy. The mass percentage ratio of Ti to Sc is not higher than 1.2, and the main reason is that when the mass percentage ratio of Ti to Sc is too high, the alloy forms thick long-strip Al3(Ti, Sc) phases in the solidification process, the precipitated phases are difficult to dissolve back in the subsequent solid solution treatment, the available Sc element and Ti element are greatly consumed, the spheroidization effect of the Sc element on eutectic silicon is reduced, and the subsequent aging strengthening effect is reduced. Meanwhile, the mass percentage ratio of Si to (Sc + Ti) is not lower than 9, mainly because when the ratio of Si to (Sc + Ti) is too low, the alloy generates an insoluble AlSi2ScTi eutectic phase in the solidification process, consumes a part of Sc and Ti elements, weakens the metamorphism and aging strengthening effects, and meanwhile, the phase is a brittle phase and has a certain splitting effect on a matrix. Experimental results show that when the Si content is 4.3%, the Sc content is 0.28% and the Ti content is 0.24%, after the alloy is subjected to solid solution at 540 ℃ for 24h +160 ℃ and aged for 8h, the tensile strength of the alloy is only 296MPa, the elongation is reduced to 3%, and the comprehensive performance of the alloy is inferior to that of the traditional ZL114A alloy.

The embodiments of the present invention have been described in detail, but the description is only for the purpose of describing the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention should be covered by the present patent.

Claims

1. A cast aluminum-silicon alloy, characterized in that:

the cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 3.5-3.9%, Mg: 0.62 to 0.85%, Ti: 0.20 to 0.35%, Sb: 0.01-0.04%, Sc: 0.18-0.3%, impurities less than or equal to 0.15%, and the balance of aluminum, wherein Ti: the mass percentage ratio of Sc is not higher than 1.2, and Si: the mass percentage ratio of (Sc + Ti) is not less than 9.

2. The cast aluminum-silicon alloy according to claim 1, characterized in that:

wherein, the content of Si is as follows: 3.8 to 3.9 percent.

3. The cast aluminium silicon alloy according to claim 1 or 2, characterized in that:

wherein the content of Mg is as follows: 0.62 to 0.65 percent.

4. The cast aluminum-silicon alloy according to claim 1, characterized in that:

wherein the mass percentage of Ti is 0.20-0.30%.

5. The cast aluminum-silicon alloy according to claim 1, characterized in that:

wherein the mass percentage of Sb is 0.02-0.03%.

6. The cast aluminum-silicon alloy according to claim 1, characterized in that:

wherein the mass percent of Sc is 0.18-0.28%.

7. A method of manufacturing a cast aluminium silicon alloy according to any one of claims 1 to 6, characterised in that the manufacturing method comprises the steps of:

the first step is as follows: firstly, heating a smelting furnace to a preheating temperature for heat preservation, then adding aluminum, Si, Ti and Sc components according to mass percent, heating to be molten, overheating to 800-820 ℃, preserving heat for 2-3 h, and stirring for 10-15min after the melting is finished;

thirdly, adding a refining agent accounting for 0.3-0.6% of the total mass of the cast aluminum-silicon alloy melt, stirring for 10-15min, and then performing inert gas blowing treatment;

8. The method of manufacturing a cast aluminium-silicon alloy according to claim 7, characterised in that:

in the first step, pure aluminum is used as the aluminum, and the Si, Ti and Sc components are in the form of master alloys, wherein the master alloys comprise AlSi12, AlTi4 and AlSc 2.

9. The method of manufacturing a cast aluminium-silicon alloy according to claim 8, characterised in that:

in the second step, the Mg added is pure Mg; the Sb added was in the form of an AlSb4 master alloy.