1. A high-strength and high-toughness cast aluminum-silicon alloy is characterized in that: the aluminum-silicon alloy comprises the following components in percentage by mass: si: 8.0-9.0 wt.%, Cu: 3.0-3.5 wt.%, Mg: 0.30-0.40 wt.%, Mn: 0.10-0.20 wt.%, B: 0.05-0.08 wt.%, Sb: 0.05-0.10 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al;

the preparation method of the aluminum-silicon alloy comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-Si alloy at 730-750 ℃, preserving heat for 45-60 min, then adding an Al-Mn alloy and an Al-Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 20-30 min, cooling to 700-710 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 5-10 min to obtain a mixed melt 1;

the Al-Si alloy is any one of Al-10Si, Al-15Si or Al-25Si alloy; the Al-Mn alloy is any one of Al-10Mn, Al-15Mn or Al-25Mn alloy; the Al-Cu alloy is any one of Al-10Cu alloy, Al-20Cu, Al-30Cu or Al-50Cu alloy;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding an Al-B refiner into the melt, uniformly stirring, standing for 5-10 min, adding Sb serving as a modifier, uniformly stirring, and standing for 10-20 min to obtain a mixed melt 2, wherein the Al-B refiner is any one of Al-3B, Al-4B or Al-5B refiner;

(3) pressing a refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 3-5 min, standing for 5-10 min, introducing high-purity argon into the melt, continuously performing degassing, impurity removing and refining treatment for 3-5 min, standing for 5-10 min after slagging, injecting the melt into an iron mold preheated to 200-250 ℃ at the temperature of 700-720 ℃ after slagging, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), performing solid solution treatment, firstly, preserving the heat of the sample at 500-510 ℃ for 6-8 h, then, heating to 530-540 ℃, preserving the heat for 2-4 h, and then performing water quenching to obtain a solid solution sample;

(5) and (4) carrying out aging treatment on the solid solution sample obtained in the step (4), firstly, preserving the temperature of the solid solution sample at 60-70 ℃ for 7-8 h, then, raising the temperature to 160-170 ℃ and preserving the temperature for 5-6 h, and then, carrying out water quenching to obtain the high-strength and high-toughness cast aluminum-silicon alloy.

2. A shank as set forth in claim 1The high-toughness cast aluminum-silicon alloy is characterized in that: the refining agent in the step (3) is C₂Cl₆Or KF, which accounts for 0.40-0.50 wt.% of the mass of the alloy ingot.

Background

The aluminum alloy has the advantages of small density, high specific strength, corrosion resistance, easy processing and forming, recyclability and the like, and is widely applied to the fields of transportation, electronic and electric appliances, mechanical equipment, buildings and the like. With the development of light weight of automobiles, parts such as automobile steering knuckles, air bag supporting arms, brake calipers, damping towers, suspension supports, control arms, engine cylinder bodies, cylinder covers and the like are in urgent need of replacing steel with aluminum. Because the parts belong to important stressed structural parts on the automobile, in order to improve the safety and service life of the automobile, the parts also have higher requirements on the comprehensive mechanical properties of the aluminum alloy, such as higher strength, excellent plasticity and fracture toughness.

The cast aluminum alloy has the obvious advantages of high production efficiency and low cost, and is a widely adopted production process for the current automobile parts. Currently, the most common materials used in the casting field are cast aluminum silicon alloys, such as a356, ADC10, ADC12, and the like. Although the cast aluminum-silicon alloy has better casting fluidity and machining performance, the problems of low strength, poor plasticity, insufficient fracture toughness and the like commonly exist in the cast aluminum-silicon alloy at present, for example, the tensile strength of the A356 cast aluminum-silicon alloy in a T6 heat treatment state is usually lower than 280MPa, the yield strength is lower than 240MPa, the elongation is lower than 7%, and the strength and the plasticity can not meet the requirements of most automobile stressed structural members.

The Al-Si alloy casting process is very important, and the purity of raw materials, the addition sequence of the raw materials, the heat preservation time, the casting temperature, deslagging and degassing and the like all have obvious influence on the quality of a melt. The content of Si element, the content ratio of Cu/Mg and the use of inoculation alterant of the Al-Si alloy casting alloy all have obvious influence on the mechanical property of the alloy. In the prior art, a heat treatment process is generally adopted to carry out heat treatment on cast aluminum-silicon alloy, namely a single-stage solid solution or single-stage aging process, and the single-stage solid solution aging process can improve the strength of the alloy to a certain extent but is not beneficial to improving the plasticity of the alloy. Therefore, how to synthesize the cast aluminum alloy by adjusting the casting aluminum-silicon alloy process, the optimization of the components and the heat treatment process is a technical problem which needs to be solved urgently at present.

Disclosure of Invention

In order to solve the technical problem, the cast aluminum-silicon alloy with high strength and toughness comprises the following components in percentage by mass: si: 8.0-9.0 wt.%, Cu: 3.0-3.5 wt.%, Mg: 0.30-0.40 wt.%, Mn: 0.10-0.20 wt.%, B: 0.05-0.08 wt.%, Sb: 0.05-0.10 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al;

the preparation method of the aluminum-silicon alloy comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-Si alloy at 730-750 ℃, preserving heat for 45-60 min, then adding an Al-Mn alloy and an Al-Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 20-30 min, cooling to 700-710 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 5-10 min to obtain a mixed melt 1;

the Al-Si alloy is any one of Al-10Si, Al-15Si or Al-25Si alloy; the Al-Mn alloy is any one of Al-10Mn, Al-15Mn or Al-25Mn alloy; the Al-Cu alloy is any one of Al-10Cu alloy, Al-20Cu, Al-30Cu or Al-50Cu alloy;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding an Al-B refiner into the melt, uniformly stirring, standing for 5-10 min, adding Sb serving as a modifier, uniformly stirring, and standing for 10-20 min to obtain a mixed melt 2, wherein the Al-B refiner is any one of Al-3B, Al-4B or Al-5B refiner;

(3) pressing a refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 3-5 min, standing for 5-10 min, introducing high-purity argon into the melt, continuously performing degassing, impurity removing and refining treatment for 3-5 min, standing for 5-10 min after slagging, injecting the melt into an iron mold preheated to 200-250 ℃ at the temperature of 700-720 ℃ after slagging, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), performing solid solution treatment, firstly, preserving the heat of the sample at 500-510 ℃ for 6-8 h, then, heating to 530-540 ℃, preserving the heat for 2-4 h, and then performing water quenching to obtain a solid solution sample;

(5) and (4) carrying out aging treatment on the solid solution sample obtained in the step (4), firstly, preserving the temperature of the solid solution sample at 60-70 ℃ for 7-8 h, then, raising the temperature to 160-170 ℃ and preserving the temperature for 5-6 h, and then, carrying out water quenching to obtain the high-strength and high-toughness cast aluminum-silicon alloy.

Further, the refining agent in the step (3) is C₂Cl₆Or KF, which accounts for 0.40-0.50 wt.% of the mass of the alloy ingot.

Compared with the prior art, the invention has the following advantages:

(1) the alloy casting process is optimized, so that the alloy melt quality and the ingot casting compactness are obviously improved;

(2) the composition of main alloy elements of Si, Cu and Mg is optimized, so that the cast aluminum-silicon alloy can greatly improve the alloy strength on the basis of ensuring the casting fluidity;

(3) the two-stage solid solution and two-stage aging heat treatment process is adopted, so that the shaping and the strength of the alloy are further improved; the yield strength of the cast aluminum-silicon alloy is more than or equal to 300MPa, the tensile strength is more than or equal to 419MPa, and the fracture elongation is more than or equal to 11.8 percent.

Drawings

FIG. 1 is a graph comparing the mechanical properties of alloys obtained in example 1 and comparative example 1, and comparative example 2 and comparative example 3.

Detailed Description

In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples, and it should be understood that the specific examples described herein are only for explaining the present invention and are not intended to limit the present invention.

Example 1:

the cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 8.0 wt.%, Cu: 3.0 wt.%, Mg: 0.30 wt.%, Mn: 0.10 wt.%, B: 0.05 wt.%, Sb: 0.05 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al; the preparation method comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-20Si alloy at 730 ℃, preserving heat for 45min, then adding an Al-20Mn alloy and an Al-50Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 20min, cooling to 700 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 5min to obtain a mixed melt 1;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding Al-3B into the melt, stirring uniformly, standing for 5min, adding a modifier Sb, stirring uniformly, and standing for 10min to obtain a mixed melt 2;

(3) c of 0.45 wt.% of melt mass₂Cl₆Pressing the refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 3min, and standing for 5 min; introducing high-purity argon into the melt, continuing for 3min for degassing, removing impurities and refining, then slagging, and standing for 5 min; after slagging, injecting the melt into an iron mold preheated to 250 ℃ at the temperature of 700 ℃, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), performing solution treatment, preserving heat of the sample at 500 ℃ for 6h in a box furnace, then heating to 530 ℃ and preserving heat for 2h, and then performing water quenching to obtain a solid solution sample;

(5) and (4) performing aging treatment on the solid solution sample obtained in the step (4), preserving the temperature of the solid solution sample in an oil bath furnace at 60 ℃ for 7h, preserving the temperature at 160 ℃ for 5h, and performing water quenching to obtain the high-strength and high-toughness cast aluminum-silicon alloy.

Example 2:

the cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 8.5 wt.%, Cu: 3.2 wt.%, Mg: 0.35 wt.%, Mn: 0.15 wt.%, B: 0.06 wt.%, Sb: 0.08 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al; the preparation method comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-20Si alloy at 750 ℃, then preserving heat for 50min, then adding an Al-20Mn alloy and an Al-50Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 25min, cooling to 700 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 10min to obtain a mixed melt 1;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding Al-3B into the melt, uniformly stirring, standing for 10min, adding a modifier Sb, uniformly stirring, and standing for 15min to obtain a mixed melt 2;

(3) c of 0.40 wt.% of melt mass₂Cl₆Pressing the refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 4min, and standing for 8 min; introducing high-purity argon into the melt, continuing for 3min for degassing, removing impurities and refining, then slagging, and standing for 8 min; after slag removal, injecting the melt into an iron mold preheated to 250 ℃ at the temperature of 710 ℃, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), performing solution treatment, preserving heat of the sample at 500 ℃ for 8h in a box furnace, then heating to 530 ℃ and preserving heat for 4h, and then performing water quenching to obtain a solid solution sample;

(5) and (4) performing aging treatment on the solid solution sample obtained in the step (4), preserving the temperature of the solid solution sample in an oil bath furnace at 65 ℃ for 8h, preserving the temperature at 165 ℃ for 6h, and performing water quenching to obtain the high-strength and high-toughness cast aluminum-silicon alloy.

Example 3:

the cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 9.0 wt.%, Cu: 3.5 wt.%, Mg: 0.40 wt.%, Mn: 0.20 wt.%, B: 0.08 wt.%, Sb: 0.10 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al; the preparation method sequentially comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-20Si alloy at 750 ℃, preserving heat for 60min, then adding an Al-20Mn alloy and an Al-50Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 30min, cooling to 700 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 8min to obtain a mixed melt 1;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding Al-3B into the melt, uniformly stirring, standing for 10min, adding a modifier Sb, uniformly stirring, and standing for 20min to obtain a mixed melt 2;

(3) c of 0.50 wt.% of melt mass₂Cl₆Pressing the refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 5min, and standing for 10 min; introducing high-purity argon into the melt, continuing for 3min for degassing, removing impurities and refining, then slagging, and standing for 10 min; after slag removal, injecting the melt into an iron mold preheated to 250 ℃ at the temperature of 720 ℃, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), performing solid solution treatment, preserving heat of the sample at 510 ℃ for 8h in a box furnace, then heating to 525 ℃ and preserving heat for 4h, and then performing water quenching to obtain a solid solution sample;

(5) and (4) performing aging treatment on the solid solution sample obtained in the step (4), preserving the temperature of the solid solution sample in an oil bath furnace at 70 ℃ for 10h, preserving the temperature at 170 ℃ for 8h, and performing water quenching to obtain the high-strength and high-toughness cast aluminum-silicon alloy.

Comparative example 1

The cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 8.0 wt.%, Cu: 3.0 wt.%, Mg: 0.30 wt.%, Mn: 0.10 wt.%, B: 0.05 wt.%, Sb: 0.05 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al; the preparation method sequentially comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-20Si alloy at 750 ℃, then preserving heat for 50min, then adding an Al-20Mn alloy and an Al-50Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 20min, cooling to 710 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 10min to obtain a mixed melt 1;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding Al-3B into the melt, uniformly stirring, standing for 10min, adding a modifier Sb, uniformly stirring, and standing for 15min to obtain a mixed melt 2;

(3) c of 0.40 wt.% of melt mass₂Cl₆Pressing the refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 4min, and standing for 8 min; introducing high-purity argon into the melt, continuing for 3min for degassing, removing impurities and refining, then slagging, and standing for 8 min; after slag removal, injecting the melt into an iron mold preheated to 250 ℃ at the temperature of 710 ℃, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), carrying out solution treatment, preserving the temperature of the sample in a box furnace at 500 ℃ for 10h, and then carrying out water quenching to obtain a solid solution sample;

(5) and (4) performing aging treatment on the solid solution sample obtained in the step (4), preserving the temperature of the solid solution sample in an oil bath furnace at 165 ℃ for 5 hours, and performing water quenching to obtain the aluminum-silicon alloy.

Comparative example 2

The cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 8.0 wt.%, Cu: 3.0 wt.%, Mg: 0.30 wt.%, Mn: 0.10 wt.%, B: 0.05 wt.%, Sb: 0.05 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al; the preparation method sequentially comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-20Si alloy at 750 ℃, then preserving heat for 50min, then adding an Al-20Mn alloy and an Al-50Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 25min, cooling to 710 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 15min to obtain a mixed melt 1;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding Al-3B into the melt, uniformly stirring, standing for 10min, adding a modifier Sb, uniformly stirring, and standing for 15min to obtain a mixed melt 2;

(3) c of 0.45 wt.% of melt mass₂Cl₆Pressing the refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 5min, and standing for 10 min; introducing high-purity argon into the melt, continuing for 3min for degassing, removing impurities and refining, then slagging, and standing for 10 min; after slag removal, injecting the melt into an iron mold preheated to 250 ℃ at the temperature of 710 ℃, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), carrying out solution treatment, firstly, keeping the temperature of the sample in a box furnace at 500 ℃ for 6h, then, heating to 530 ℃ and keeping the temperature for 2h to obtain a solid solution sample;

(5) and (4) performing aging treatment on the solid solution sample obtained in the step (4), preserving the temperature of the solid solution sample in an oil bath furnace at 160 ℃ for 5 hours, and performing water quenching to obtain the aluminum-silicon alloy.

Comparative example 3:

the cast aluminum-silicon alloy comprises the following components in percentage by mass: si: 8.0 wt.%, Cu: 3.0 wt.%, Mg: 0.30 wt.%, Mn: 0.10 wt.%, B: 0.05 wt.%, Sb: 0.05 wt.%, the content of inevitable impurities is less than or equal to 0.2 wt.%, and the balance is Al; the preparation method sequentially comprises the following steps:

(1) preparing materials according to the proportion of alloy components, melting an aluminum ingot and an Al-20Si alloy at 750 ℃, then preserving heat for 50min, then adding an Al-20Mn alloy and an Al-50Cu alloy, uniformly stirring after the intermediate alloy is melted, standing for 25min, cooling to 710 ℃, slagging, pressing a magnesium ingot below the liquid level, uniformly stirring after the mixture is melted, and standing for 15min to obtain a mixed melt 1;

(2) heating the mixed melt 1 obtained in the step (1) to 720 ℃, slagging, adding Al-3B into the melt, uniformly stirring, standing for 10min, adding a modifier Sb, uniformly stirring, and standing for 15min to obtain a mixed melt 2;

(3) c of 0.50 wt.% of melt mass₂Cl₆Pressing the refining agent to the bottom of the mixed melt 2 obtained in the step (2) by using a pressing cover, stirring for 5min, and standing for 15 min; introducing high-purity argon into the melt, continuing for 3min for degassing, removing impurities and refining, then slagging, and standing for 15 min; after slag removal, injecting the melt into an iron mold preheated to 250 ℃ at the temperature of 710 ℃, and solidifying to obtain an alloy ingot;

(4) cutting a sample at a position of 50-100 mm of the alloy ingot obtained in the step (3), carrying out solution treatment, preserving the temperature of the sample in a box furnace at 500 ℃ for 10h, and then carrying out water quenching on the sample to dissolve the sample;

(5) and (4) performing aging treatment on the solid solution sample obtained in the step (4), firstly preserving the temperature of the solid solution sample in an oil bath furnace at 60 ℃ for 7h, then raising the temperature of the solid solution sample to 160 ℃ and preserving the temperature for 5h, and then performing water quenching to obtain the aluminum-silicon alloy.

The cast aluminum-silicon alloys of examples 1 to 3 and comparative examples 1 to 3 were processed into standard tensile specimens according to the national standard of the people's republic of China GB/T228.1-2010, and room-temperature tensile mechanical properties were performed on an Shimadzu tensile tester at a tensile rate of 0.6mm/min, and the test results are shown in Table 1.

TABLE 1 statistical tables of mechanical properties of alloys of examples 1-3 and comparative examples 1-3

Through comparison, the invention can obviously improve the strength, plasticity and toughness of the cast aluminum-silicon alloy by optimizing the alloy components, perfecting the casting process and adopting the secondary solid solution and secondary aging processes.