阅读说明：本技术 一种高强韧耐磨Al-Mg-Si系铸造铝合金及其制备方法 (High-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy and preparation method thereof ) 是由 李凯 宋宏磊 王宏明 李桂荣 朱万涛 于 2021-01-19 设计创作，主要内容包括：本发明涉及一种高强韧耐磨Al-Mg-Si系铸造铝合金及其制备方法,属于有色金属技术领域。所述铝合金中的主要的化学成分按质量百分数计为：7.8-8.8%的Si、小于0.15%的Fe、小于0.05%的Zn、小于0.05%的Mn、小于0.01%的Cu、0.4-0.5%的Mg、余量为Al。本发明的铝合金制备过程为熔炼、精炼、铸造、短时热处理。本发明的主要优点有：采用原位化学反应技术、颗粒增强体强化、多种稀有金属复合变质细化、微波加热技术、短时热处理节约能耗等。制造出的铝合金具有强韧性高、耐磨性好等特点。(The invention relates to a high-strength, high-toughness and wear-resistant Al-Mg-Si series cast aluminum alloy and a preparation method thereof, belonging to the technical field of nonferrous metals. The aluminum alloy comprises the following main chemical components in percentage by mass: 7.8 to 8.8 percent of Si, less than 0.15 percent of Fe, less than 0.05 percent of Zn, less than 0.05 percent of Mn, less than 0.01 percent of Cu, 0.4 to 0.5 percent of Mg and the balance of Al. The preparation process of the aluminum alloy comprises smelting, refining, casting and short-time heat treatment. The main advantages of the invention are: the in-situ chemical reaction technology, the strengthening of the particle reinforcement, the composite modification and refinement of various rare metals, the microwave heating technology, the short-time heat treatment and the like are adopted, so that the energy consumption is saved. The manufactured aluminum alloy has the characteristics of high strength and toughness, good wear resistance and the like.)

1. A preparation method of high-strength, high-toughness and wear-resistant Al-Mg-Si series cast aluminum alloy is characterized by comprising the following steps:

1) smelting: in argon atmosphere, putting raw materials in percentage by mass into a melting furnace, heating to 730-770 ℃ and smelting for 2h to form an aluminum alloy melt, 7.8-8.8% of Si, less than 0.15% of Fe, less than 0.05% of Zn, less than 0.05% of Mn, less than 0.01% of Cu, 0.4-0.5% of Mg and the balance of Al;

2) refining: adding 1-2 of rare earth elements La, Y, Er, Yb, Ce, Re and Nd, and Sr, Ti and B into the aluminum alloy melt in the step 1)₄C powder, the addition of which is respectively 0.15-0.02%, 0.04-0.05%, 0.05-0.06% and 0.5-1% in percentage by mass, and a refining agent and a deslagging agent are added, stirring is carried out, nitrogen is continuously injected, and the refining time is 20-25 min;

3) casting: casting the aluminum alloy after refining;

4) microwave short-time heat treatment: the short-time solution treatment temperature is 540-560 ℃, and the time is 100-120 min; the one-time short-term effective treatment temperature is 160-; the secondary short-term time effective treatment temperature is 170-180 ℃, and the time is 80-90 min.

2. The preparation method of the high-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy according to claim 1, characterized by comprising the following steps: the metal material in the step 1) further comprises Pb which is not more than 0.01 percent, Sn which is not more than 0.01 percent, Ni which is not more than 0.02 percent, Sb which is not more than 0.002 percent and Ca which is not more than 0.01 percent in mass percentage.

3. The preparation method of the high-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy according to claim 1, characterized by comprising the following steps: the addition amount of the refining agent and the deslagging agent in the step 2) is 0.06-0.09% of the total weight of the molten metal.

4. The method for preparing the high-strength, high-toughness and wear-resistant Al-Mg-Si cast aluminum alloy according to claim 3, wherein the method comprises the following steps: the slag remover comprises 8-12% of cryolite, 20-22% of sodium chloride, 20-22% of potassium chloride, 18-22% of sodium chlorosilicate, 16-20% of potassium chlorotitanate and 10-14% of potassium chloroborate in percentage by mass.

5. The method for preparing the high-strength, high-toughness and wear-resistant Al-Mg-Si cast aluminum alloy according to claim 3, wherein the method comprises the following steps: the refining agent comprises, by mass, 14-16% of cryolite, 14-16% of sodium chloride, 20-22% of potassium chloride, 8-12% of sodium chlorosilicate, 8-12% of hexachloroethane, 14-16% of sodium fluoride and 14-16% of sodium fluorosilicate.

6. The preparation method of the high-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy according to claim 1, characterized by comprising the following steps: the nitrogen flushing speed in the step 2) is 1-2 ml/s.

7. The preparation method of the high-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy according to claim 1, characterized by comprising the following steps: in the step 3), the casting pressure is 1500mbar, the heat preservation time is 60s, and the casting temperature is 680-710 ℃.

8. The preparation method of the high-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy according to claim 1, characterized by comprising the following steps: the power of the microwave heat treatment furnace in the step 4) is 5-9 kW.

9. The high-strength-toughness wear-resistant Al-Mg-Si series cast aluminum alloy prepared by the preparation method of any one of claims 1 to 8, which is characterized in that the aluminum alloy mainly comprises the following chemical components in percentage by mass: 7.8 to 8.8 percent of Si, less than 0.15 percent of Fe, less than 0.05 percent of Zn, less than 0.05 percent of Mn, less than 0.01 percent of Cu, 0.4 to 0.5 percent of Mg and the balance of Al.

10. The high-strength, high-toughness and wear-resistant Al-Mg-Si cast aluminum alloy of claim 9 is characterized by having a tensile strength of 290-321 MPa, a yield strength of 275-290 MPa, an elongation of 8-11% and a hardness of 95-107 HV.

Technical Field

The invention belongs to the field of aluminum alloy materials, and particularly relates to a high-strength, high-toughness and wear-resistant Al-Mg-Si series cast aluminum alloy and a preparation method thereof.

Background

The cast aluminum alloy has good casting performance and can be made into parts with complex shapes; no bulky additional equipment is required; has the advantages of saving metal, reducing cost, reducing working hours and the like, and is widely applied to the aviation industry and the civil industry. The method is used for manufacturing beams, gas turbine blades, pump bodies, hangers, hubs, air inlet lips, engine casings and the like. The cast aluminum alloy has the following advantages in actual production: the product quality is good, and the size precision of the casting is high; the strength and the hardness are higher, the strength is generally improved by 25-30% compared with sand casting, but the elongation is reduced by about 70%; the size is stable, and the interchangeability is good; the die casting method can be used for die-casting aluminum thin-wall complex castings; the production efficiency is high, and the machine productivity is high; the die-casting aluminum alloy has excellent economic effect, and because the die-casting aluminum alloy has the advantages of accurate size, smooth surface and the like, the die-casting aluminum alloy is generally used directly without mechanical processing or has small processing amount, the metal utilization rate is improved, and a large amount of processing equipment and working hours are reduced; the cast casting is low in price and the like.

Compared with wrought aluminum alloy, cast aluminum alloy has many defects, and cast aluminum alloy products have generally low mechanical properties, low corrosion resistance and wear resistance and the like, so the invention adopts an in-situ chemical reaction technology, a particle reinforcement strengthening mechanism, a composite modification mechanism of various rare metals, a microwave short-time heat treatment process and the like, so that the comprehensive properties of the Al-Mg-Si series cast aluminum alloy are obviously improved, and the research progress of domestic cast aluminum alloy is greatly promoted.

The microwave heating is to convert microwave energy absorbed in the material into heat energy, and the microwave source does not generate heat radiation, so the heat loss is less, the efficiency of converting the microwave energy into the heat energy is as high as about 80 percent, in addition, the microwave heating has the characteristic of low-temperature quick firing, the internal energy of the material is increased under the action of a microwave field, and the densification process is effectively accelerated. Meanwhile, the diffusion coefficient of the material is improved, and the grain boundary diffusion capability is greatly enhanced. In addition, the heat conduction mode from inside to outside unique to microwave heating reduces the transfer time from outside to inside of the traditional heating, has high heating speed and high energy utilization rate, thereby realizing low-temperature rapid heat treatment on the material, and can save energy by 70-90 percent compared with the traditional heat treatment heating method. And the microwave can not generate environmental pollution such as waste gas, dust and the like in the process of heating the material.

Disclosure of Invention

The invention adopts an in-situ chemical reaction technology, a particle reinforcement mechanism, a multiple rare metal composite modification mechanism, a microwave short-time heat treatment process and the like, and aims to optimize the defects of the existing cast aluminum alloy product, improve the strength, toughness, wear resistance and the like of the cast aluminum alloy product and reduce the production energy consumption.

The preparation method of the high-strength, high-toughness and wear-resistant Al-Mg-Si series cast aluminum alloy comprises the following steps:

1) smelting: in argon atmosphere, putting raw materials in percentage by mass into a melting furnace, heating to 730-770 ℃ and smelting for 2h to form an aluminum alloy melt, 7.8-8.8% of Si, less than 0.15% of Fe, less than 0.05% of Zn, less than 0.05% of Mn, less than 0.01% of Cu, 0.4-0.5% of Mg and the balance of Al;

2) refining: adding 1-2 of rare earth elements La, Y, Er, Yb, Ce, Re and Nd, and Sr, Ti and B into the aluminum alloy melt in the step 1)₄C powder, the addition of which is respectively 0.15-0.02%, 0.04-0.05%, 0.05-0.06% and 0.5-1% in percentage by mass, and a refining agent and a deslagging agent are added, stirring is carried out, nitrogen is continuously injected, and the refining time is 20-25 min;

3) casting: casting the aluminum alloy after refining;

4) microwave short-time heat treatment: the short-time solution treatment temperature is 540-560 ℃, and the time is 100-120 min; the one-time short-term effective treatment temperature is 160-; the secondary short-term time effective treatment temperature is 170-180 ℃, and the time is 80-90 min.

Preferably, the metal material in the step 1) further comprises, in mass percent, not more than 0.01% of Pb, not more than 0.01% of Sn, not more than 0.02% of Ni, not more than 0.002% of Sb, not more than 0.01% of Ca.

Preferably, the refining agent and the deslagging agent in the step 2) are added in an amount of 0.06-0.09% by weight of the molten metal.

Preferably, the slag remover comprises 8-12% of cryolite, 20-22% of sodium chloride, 20-22% of potassium chloride, 18-22% of sodium chlorosilicate, 16-20% of potassium chlorotitanate and 10-14% of potassium chloroborate in percentage by mass.

Preferably, the refining agent comprises 14-16% of cryolite, 14-16% of sodium chloride, 20-22% of potassium chloride, 8-12% of sodium chlorosilicate, 8-12% of hexachloroethane, 14-16% of sodium fluoride and 14-16% of sodium fluosilicate in percentage by mass.

Preferably, the nitrogen flushing speed in the step 2) is 1-2 ml/s.

Preferably, the casting pressure in the step 3) is 1500mbar, the holding time is 60s, and the casting temperature is 680-.

Preferably, the power of the microwave heat treatment furnace in the step 4) is 5-9 kW.

The high-strength, high-toughness and wear-resistant Al-Mg-Si series cast aluminum alloy prepared by the preparation method is characterized in that the aluminum alloy mainly comprises the following chemical components in percentage by mass: 7.8 to 8.8 percent of Si, 0.4 to 0.5 percent of Mg, less than 0.15 percent of Fe, less than 0.05 percent of Zn, less than 0.05 percent of Mn, less than 0.01 percent of Cu and the balance of Al.

Furthermore, the high-strength and high-toughness wear-resistant Al-Mg-Si series cast aluminum alloy has the tensile strength of 290-321 Mpa, the yield strength of 275-290 Mpa, the elongation of 8-11% and the hardness of 95-107 HV.

The beneficial effects of the invention are as follows:

(1) 1-2 elements of rare earth elements La, Y, Er, Yb, Ce, Re and Nd and Sr are added, during refining, multiple rare earth elements can perform composite modification and refinement on the aluminum alloy, an alpha-Al phase in the aluminum alloy is refined, the secondary dendrite arm spacing of the alloy and the length of eutectic Si are reduced, and the coarse needle-shaped eutectic Si is converted into particles.

(2) Rare elements react in combination with other elements to form other phases, such as: AlSiYMg, AlSiLa, AlSiY, AlSiYTi and the like, and the size of the phases is small and is only dozens of microns, so that the phases can play a role in precipitation strengthening as strengthening phases.

(3) Added Ti and B₄C powder because B₄C has a high melting point and does not react during refining, but B is subjected to microwave heating treatment₄C can be reacted with TiIn situ chemical reaction to produce TiB₂And a ceramic particle phase of TiC, the reinforcing phase reinforcing the aluminum alloy; and not completely reacted B after heat treatment₄The C particles have high self wear resistance and play a certain role in improving the wear resistance of the aluminum alloy; in addition, B₄The C particles also strengthen the aluminum alloy in the form of a particulate reinforcing phase.

(4) Compared with the traditional heat treatment process, the heat treatment method has the advantages that the heat treatment mode is changed, the heat treatment time is greatly shortened, the heat treatment energy consumption is saved by more than 70 percent based on the characteristic of low-temperature quick firing of microwave heating, the time is shortened by more than 2 times, in addition, through twice short-time aging treatment, the strengthening phase can be fully separated out, and the strength and the toughness can be simultaneously improved.

Drawings

FIG. 1 is a microstructure of a scanning electron microscope of a high-toughness wear-resistant Al-Mg-Si cast aluminum alloy obtained in example 1 of the present invention;

FIG. 2 is a microstructure view of a scanning electron microscope of a high-toughness wear-resistant Al-Mg-Si cast aluminum alloy obtained in example 2 of the present invention;

FIG. 3 is a microstructure view of a scanning electron microscope of a high-toughness wear-resistant Al-Mg-Si cast aluminum alloy obtained in example 3 of the present invention.

The specific implementation mode is as follows:

the invention is further illustrated by the following examples.

Example 1:

1) smelting: under argon atmosphere, putting 8.8% of Si, 0.15% of Fe, 0.05% of Zn, 0.05% of Mn, 0.01% of Cu, 0.5% of Mg, 0.01% of Pb, 0.01% of Sn, 0.02% of Ni, 0.002% of Sb, 0.01% of Ca and the balance of Al into a melting furnace in proportion, heating to 740 ℃ and melting for 2 hours to form aluminum alloy liquid;

2) refining: adding Y, Sr, Ti and B into the aluminum alloy solution₄C powder, adding 0.02%, 0.05%, 0.06% and 1% respectively, and adding 0.08% and 0.09% respectively of refining agent and deslagging agent, wherein the refining agent comprises 15% of refining agent by massCryolite, 15% of sodium chloride, 21% of potassium chloride, 11% of sodium chlorosilicate, 11% of hexachloroethane, 15% of sodium fluoride and 15% of sodium fluosilicate; the added slag remover comprises 10 percent of cryolite, 20 percent of sodium chloride, 20 percent of potassium chloride, 20 percent of sodium chlorosilicate, 20 percent of potassium chlorotitanate and 10 percent of potassium chloroborate in percentage by mass; stirring, and continuously charging nitrogen at a nitrogen charging speed of 2ml/s for 25 min;

3) casting: casting the aluminum alloy after refining, wherein the casting pressure is 1500mbar, the heat preservation time is 60s, and the casting temperature is 710 ℃;

4) microwave short-time heat treatment: the short-time solution treatment temperature is 560 ℃, and the time is 120 min; the one-time short-term aging treatment temperature is 170 ℃, and the time is 90 min; the secondary short-term aging treatment temperature is 180 ℃ and the time is 90 min.

FIG. 1 is a microstructure of a scanning electron microscope of a high-toughness wear-resistant Al-Mg-Si cast aluminum alloy obtained in example 1 of the present invention; most alpha-Al phase crystal grains in the structure of the prepared Al-Mg-Si series cast aluminum alloy are refined into isometric grains, the silicon phase becomes fine, but individual silicon phase crystal grains are still relatively coarse, the size of the refined alpha-Al crystal grains is 30-60um, and Al is generated in the aluminum alloy by reaction₄Sr、Al₃Y、AlSiYMg、TiB₂And TiC and the like as reinforcing particles. Taking the finished product to perform performance test, and obtaining the following results: the tensile strength was 291MPa, the yield strength was 275MPa, the elongation was 11.2%, and the hardness was 95.5 HV.

Example 2:

1) smelting: under argon atmosphere, adding metal materials of 8.3% of Si, 0.13% of Fe, 0.05% of Zn, 0.05% of Mn, 0.01% of Cu, 0.45% of Mg, 0.01% of Pb, 0.01% of Sn, 0.02% of Ni, 0.002% of Sb, 0.01% of Ca and the balance of Al into a melting furnace in proportion, heating to 740 ℃ and melting for 2 hours to form aluminum alloy liquid;

2) refining: adding La, Y, Sr, Ti and B into the aluminum alloy solution in the step 1)₄C powder, the addition amounts of which are respectively 0.15%, 0.04%, 0.05% and 0.75%, and refining agent and deslagging agent are addedAll are 0.07 percent, and the added refining agents comprise 15 percent of cryolite, 15 percent of sodium chloride, 21 percent of potassium chloride, 11 percent of sodium chlorosilicate, 11 percent of hexachloroethane, 15 percent of sodium fluoride and 15 percent of sodium fluosilicate in percentage by mass; the added slag remover comprises 10 percent of cryolite, 20 percent of sodium chloride, 20 percent of potassium chloride, 20 percent of sodium chlorosilicate, 20 percent of potassium chlorotitanate and 10 percent of potassium chloroborate in percentage by mass; stirring, and continuously charging nitrogen at a nitrogen charging speed of 2ml/s for 25 min;

3) casting: casting the aluminum alloy after refining, wherein the casting pressure is 1500mbar, the heat preservation time is 60s, and the casting temperature is 710 ℃;

4) microwave short-time heat treatment: the short-time solution treatment temperature is 550 ℃, and the time is 110 min; the one-time short-term aging treatment temperature is 165 ℃ and the time is 85 min; the second short-term aging treatment temperature is 175 ℃, and the time is 85 min.

FIG. 2 is a microstructure view of a scanning electron microscope of a high-toughness wear-resistant Al-Mg-Si cast aluminum alloy obtained in example 2 of the present invention; as can be seen from the figure, the rare metal composite modification refines alpha-Al phase in the aluminum alloy, reduces the secondary dendrite arm spacing and the eutectic silicon length of the alloy, enables the coarse needle-like eutectic silicon to be converted into particles, the size of alpha-Al crystal particles is converted into 30-50um, and AlSiY, AlSiLa and TiB are generated in the aluminum alloy through reaction₂And TiC and the like. Taking the finished product to perform performance test, and obtaining the following results: the tensile strength is 301MPa, the yield strength is 283MPa, the elongation is 8.9 percent, and the hardness is 103.1 HV.

Example 3:

1) smelting: in argon atmosphere, adding 7.8% of Si, 0.11% of Fe, 0.05% of Zn, 0.05% of Mn, 0.01% of Cu, 0.4% of Mg, 0.01% of Pb, 0.01% of Sn, 0.02% of Ni, 0.002% of Sb, 0.01% of Ca and the balance of Al into a melting furnace in proportion, heating to 740 ℃ and melting for 2 hours to form aluminum alloy liquid;

2) refining: adding rare earth elements of La, Nd, Sr, Ti and B into the aluminum alloy solution in the step 1)₄C powder, the addition amounts of which are respectively 0.15%, 0.04%, 0.05% and 0.5%, and a refining agent and a deslagging agent are addedThe addition amount of the refining agent is 0.07 percent, and the refining agent comprises 15 percent of cryolite, 15 percent of sodium chloride, 21 percent of potassium chloride, 11 percent of sodium chlorosilicate, 11 percent of hexachloroethane, 15 percent of sodium fluoride and 15 percent of sodium fluosilicate in percentage by mass; the added slag remover comprises 10 percent of cryolite, 20 percent of sodium chloride, 20 percent of potassium chloride, 20 percent of sodium chlorosilicate, 20 percent of potassium chlorotitanate and 10 percent of potassium chloroborate in percentage by mass; stirring, and continuously charging nitrogen at a speed of 2ml/s for 25 min;

3) casting: casting the aluminum alloy after refining, wherein the casting pressure is 1500mbar, the heat preservation time is 60s, and the casting temperature is 710 ℃;

4) microwave short-time heat treatment: the short-time solution treatment temperature is 540 ℃, and the time is 100 min; the one-time short-term aging treatment temperature is 160 ℃, and the time is 80 min; the second short-term aging treatment temperature is 170 ℃ and the time is 80 min.

FIG. 3 is a microstructure of a scanning electron microscope of a high-toughness wear-resistant Al-Mg-Si cast aluminum alloy obtained in example 3 of the present invention; according to the figure, the composite refining and modification effects of rare metals on an alpha-Al matrix and eutectic silicon particles are optimal, the strength and hardness of cast aluminum alloy are highest, the grain size of the alpha-Al matrix reaches 20-40um, the size of the eutectic Si particles reaches 1-10um, in addition, other phases are separated out in the aluminum alloy in the figure, B is₄The C particles react with the alpha-Al matrix to generate a certain amount of Al at local interfaces₃BC_(s)The phase, as a second phase, acts as a reinforcement. Taking the finished product to perform performance test, and obtaining the following results: the tensile strength is 321MPa, the yield strength is 290MPa, the elongation is 8.1 percent, and the hardness is 106.7 HV.