High-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment and method for producing the same

Abstract

The present invention provides a non-heat-treated high strength and toughness die-casting aluminum silicon alloy and its manufacturing method, in which the weight percentages of the components are Si 8.0-10.0wt.%, Mg 0.1-0.5wt.%, Mn 0.5-0.8wt.%, Cu 0.05-0.5wt.%, Ti 0.05-0.2wt.%, Sr 0.01-0.05wt.%, V 0.01-0.1wt.%, RE 0.01-0.15wt.%, Fe < 0.2wt.%, the total amount of other impurities ≦ 0.4%, the balance being Al. Sr can be used to refine eutectic silicon, and V and RE elements can be added during the manufacturing process to significantly refine the eutectic silicon structure. When the alloy contains a relatively high Si content, it can obtain high strength and toughness properties, so that the large body structural components can meet the fluidity, strength and plasticity requirements of die-cast aluminum alloy materials.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and specifically to a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment and a manufacturing method thereof.

Background Art

[0002] Under the goal of "double carbon", the country's requirements for environmental protection are increasing. With the release of the "Energy Conservation and New Energy Vehicle Technology Roadmap", the lightweighting of new energy vehicles has become a development direction that has attracted high attention. Aluminum alloy, as a common metal structural material for vehicle bodies, has a small density, high specific strength, excellent vibration damping effect, and is applied to components such as the vibration damping tower of automobiles and the rear side members of automobiles. Its lightweighting advantage is obvious, and good strength and rigidity can be achieved, and it has high fatigue resistance. Integrated design and integrated die-casting forming are beneficial to reducing the processing process and can reduce the repeated pollution to the environment. At the same time, the design of the casting structure is flexible and can meet the requirements of different products.

[0003] The body structure members of new energy vehicles generally use die-cast aluminum alloy, mainly heat-treatable high-strength and high-toughness die-cast aluminum alloy materials represented by Silafont-36 alloy (US Patent No. 6364970). This material adopts "high-vacuum die-casting + heat treatment" to achieve a yield strength of 100 - 120 MPa, a tensile strength of 180 - 220 MPa, and an elongation rate of 10 - 15% for the casting. However, for thin-walled die-cast castings, the use of this technology has the following two drawbacks. (1) High-vacuum die-casting significantly increases the process difficulty and manufacturing cost. (2) Adopting the heat treatment process causes a certain amount of deformation and bubbles in the casting, affecting the product yield rate and increasing the cost. Therefore, research institutions in various countries are actively developing high-strength and high-toughness die-cast aluminum alloy materials without heat treatment and applying them to the mass production of large and complex die-cast structural members. In particular, new energy vehicle manufacturers represented by Tesla adopt non-heat-treated alloys to manufacture large integrated body structure members, and the alloy body components used are Al7SiMgMn alloy (US Patent Application Publication No. 2005 / 0167012). This alloy cooperates with high-vacuum and then ultra-high-vacuum die-casting to manufacture parts, and adopting this technical route can alleviate the part deformation problem caused by conventional heat-treated alloys. However, there are the following two major problems. (1) The Si content in the alloy is relatively low (~7 wt.%), and the elongation rate of the material can be improved to 10 - 15%. However, low Si restricts the fluidity of the non-heat-treated alloy, and there is a risk of insufficient filling of large castings. (2) Conventional Al7SiMgMn alloys have relatively low alloy strength (typical yield strength of 110 - 120 MPa, tensile strength of 180 - 220 MPa). Large castings have a relatively thick overall wall thickness and relatively many wall thickness regions in the structural design. Therefore, when the material elongation rate is not changed or slightly decreased (guaranteeing an elongation rate > 10% to meet the rivet requirements of the body structure members), improving the Si content in the alloy can improve the material fluidity and at the same time improve the material strength, which has important significance for the optimization of large vehicle body casting structures.

[0004] Therefore, developing a high-strength and high-toughness die-cast aluminum silicon alloy without heat treatment, and researching its manufacturing and die-casting process, can meet the actual usage requirements of high-quality and high-performance aluminum alloy die-cast parts that the automotive industry increasingly demands, and become one of the goals pursued in the die-casting field.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment and a manufacturing method thereof in the background of the above prior art. On the premise of ensuring that the alloy has good casting performance, the non-heat-treated casting has excellent comprehensive mechanical properties, thereby meeting the performance requirements of vehicle body structural members, especially large-sized and thin-walled vehicle body structural members.

Means for Solving the Problems

[0007] To achieve this object, in the long-term research on die-cast aluminum alloys, the present invention has discovered that the Si content in die-cast aluminum silicon alloys has a significant impact on the casting performance, strength, and plasticity of the alloys. Generally, as the Si content increases, the strength of the alloy increases, the fluidity increases, and the plasticity decreases. The Sr element has a modification and refinement effect on the eutectic Si in the alloy, but as the Si content increases, the plasticity shows a tendency to decrease, making it difficult to achieve 10% plasticity. The present invention is mainly to solve the problem that the plasticity of the Al-Si alloy decreases under die-cast conditions after the Si content increases. As the Si content in the alloy increases, the eutectic Si content in the structure increases, and the size and shape of the eutectic Si also change accordingly, which becomes an important factor affecting the plasticity of the alloy. To solve the problem of the decrease in material plasticity due to the increase in the Si content in the alloy, the present invention creatively introduces the V element to refine the eutectic Si, thereby obtaining a microstructure of fine eutectic Si. In addition, through a large number of previous experimental verifications, it has been discovered that rare earth elements such as La, Er, Ce, etc. in rare earth elements have a composite effect with the V element, further refining the eutectic Si structure in the alloy, thereby changing the size and shape of the eutectic Si. The composite addition of V+RE generates fine eutectic Si particles in the as-cast structure, thereby ensuring that the die-cast aluminum alloy material with a high Si content still has high plasticity. On the other hand, the higher the addition amount of Si, the better the strength and fluidity of the alloy. On the other hand, the composite addition of V+RE keeps the eutectic Si in a finely dispersed state and improves the plasticity of the alloy. Furthermore, on the premise of ensuring excellent casting performance, the present invention can greatly improve the mechanical properties of die-cast aluminum silicon alloys, and obtain comprehensive mechanical properties of high strength and high toughness with both strength and formability. Thus, the object of the present invention is realized by the following technical solutions. The present invention provides a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment. The weight percentages of the components in the above-mentioned die-cast aluminum silicon alloy are Si 8.0 - 10.0 wt.%, Mg 0.1 - 0.5 wt.%, Mn 0.5 - 0.8 wt.%, Cu 0.05 - 0.5 wt.%, Ti 0.05 - 0.2 wt.%, Sr 0.01 - 0.05 wt.%, V 0.01 - 0.1 wt.%, RE 0.01 - 0.15 wt.%, and Fe < 0.2 wt.%. The total amount of other impurities is ≤ 0.4 wt%, and the balance is Al. As an embodiment of the present invention, the aforementioned RE element includes one or several of La, Ce, and Er elements.

[0008] The present invention further relates to a method for manufacturing a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment. The aforementioned manufacturing method includes the following steps. S1, Drying: Preheat the prepared raw materials of pure Al, pure Si, pure Mg, Al-Mn master alloy, Al-Ti master alloy, Al-Cu master alloy, Al-RE master alloy, and Al-V master alloy, and perform a drying treatment. S2, Smelting: After melting pure Al during the first temperature rise, add Al-Ti master alloy, Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, and pure Si. After the master alloy melts, lower the temperature. Press pure Mg into the bottom of the melt and melt it. After complete melting, raise the temperature of the alloy melt for the second time and refine it. Further, press the Al-RE master alloy into the bottom of the melt and melt it. After complete melting, let it stand to obtain a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment.

[0009] As an embodiment of the present invention, the preheating temperature in step S1 is 190 - 210 °C. As an embodiment of the present invention, the temperature of the first temperature rise in step S2 is 750 °C - 760 °C. As an embodiment of the present invention, the temperature of the temperature drop in step S2 is 680 °C - 700 °C. As an embodiment of the present invention, in step S2, after pressing pure Mg and Al-RE master alloy into the melt, it is stirred for 3 to 5 minutes to be completely melted. As an embodiment of the present invention, the temperature of the second temperature rise in step S2 is 720 to 730 °C. RE is a modifying element, and in the smelting process of aluminum alloy, the modifying element is added at the end. As an embodiment of the present invention, the refining in step S2 is specifically as follows. Using a rotary spraying device, nitrogen gas with refining agent powder is flowed into the melt for powder spraying refining, slag removal, and gas removal treatment, and then it is left standing for 10 to 15 minutes to complete the slag removal treatment and obtain the refined melt. As an embodiment of the present invention, the process parameters of the rotary spraying device are: the rotation speed for gas removal is 300 to 350 r / min, the gas removal time is 5 to 10 min, the pressure of the gas source during gas removal is 0.35 ± 0.05 MPa, and the gas flow rate is 0.2 to 0.8 sccm. As an embodiment of the present invention, the refining agent used contains one of magnesium chloride and calcium chloride. The addition amount of the refining agent is 0.2 to 0.5% of the weight of the melt. As an embodiment of the present invention, the standing time in step S2 is 10 to 15 minutes. As an embodiment of the present invention, the high-strength and high-toughness die-cast aluminum silicon alloy strengthened by the aforementioned non-heat treatment in step S2 is an alloy ingot that is further die-cast after casting or pouring. As an embodiment of the present invention, the casting temperature is 690 to 710 °C. As an embodiment of the present invention, the specific parameters of the aforementioned die-casting are as follows. The injection speed is 3 to 6 m / s, the ratio of the mold release agent to water is 1:80 to 1:120, the mold temperature is 200 to 250 °C, and the casting pressure is 30 to 100 MPa.

Advantages of the Invention

[0010] Compared with the prior art, the present invention has the following beneficial effects. 1. The non-heat-treated strengthened high-strength and tough die-cast aluminum silicon alloy manufactured by the present invention has important industrial application value. The die-cast aluminum silicon alloy can obtain excellent performance with a yield strength of 120-160 MPa, a tensile strength of 260-320 MPa, and an elongation of 10-15% under die-cast conditions (for AlSi10MnMg alloy, the as-cast tensile strength is 200-220 MPa, and the elongation is 5-8%). Moreover, good die-cast performance can be realized, which greatly meets the application requirements of large-sized thin-walled vehicle body structural members in the automotive industry. 2. The alloy achieves excellent performance with a yield strength of 120-160 MPa, a tensile strength of 260-320 MPa, and an elongation of 10-15% in the as-cast state. Compared with conventional heat-treated alloys, the heat treatment process of parts is reduced, thereby improving the qualified rate of castings and reducing the cost of castings.

Brief Description of the Drawings

[0011] Other features, objects, and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings.

Figure 1

Modes for Carrying Out the Invention

[0012] The following is not intended to limit the scope of application of the present invention, but to make the advantages and features of the present invention easier for those skilled in the art to understand. The non-heat-treatment-strengthened high-strength and tough die-cast aluminum silicon alloy provided by the present invention and its manufacturing method will be further described with examples.

[0013] Example 1 This example relates to a non-heat-treatment-strengthened high-strength and tough die-cast aluminum silicon alloy. The weight percentages of each component are: Si: 8.0 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.02 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0014] The manufacture of the non-heat-treatment-strengthened high-strength and tough die-cast aluminum silicon alloy of this example and its die-casting process include the following steps. 1) Drying: Pre-prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum, and then Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. Using a bell jar, pure Mg is pushed into the bottom area of the crucible and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes to complete the slag removal process and conduct an on-site rapid component analysis test. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the ratio of the release agent (the release agent is a solvent and needs to be diluted with water when used, and here the ratio of the release agent to water is shown) is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A1.

[0015] Example 2 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentage of each component is Si: 8.0 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, Er: 0.05 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0016] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, and Al-10Er master alloy are preheated to 200 °C and subjected to a drying process. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum, and then Al-10Ti, Al-50Cu, Al-10Mn, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. Using a plunger, pure Mg is pushed into the bottom area of the crucible and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, a refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left to stand for 12 minutes and the slag removal treatment is completed. After the refining is completed, using a plunger, the Al-10Er master alloy is pressed into the bottom area of the crucible and melted, stirred for 5 minutes until completely melted, then left to stand for 12 minutes, and an on-site rapid component analysis test is carried out. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the mold release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A2.

[0017] Example 3 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentages of each component are: Si: 8.0 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.02 wt.%, Er: 0.05 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0018] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10Er master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum, and then Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. The plunger is used to push pure Mg into the bottom area of the crucible to melt it, and then it is stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and it is aerated for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. After the refining is completed, the Al-10Er master alloy is pressed into the bottom area of the crucible using the plunger to melt it, and it is stirred for 5 minutes until completely melted. Subsequently, it is left standing for 12 minutes and an on-site rapid component analysis test is conducted. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A3.

[0019] Example 4 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentage of each component is: Si: 9.5 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.02 wt.%, Er: 0.05 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0020] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10Er master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum, and then Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. The plunger is used to push pure Mg into the bottom area of the crucible to melt it, and then it is stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, a refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and it is aerated for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. After the refining is completed, the Al-10Er master alloy is pressed into the bottom area of the crucible using the plunger to melt it, and it is stirred for 5 minutes until it is completely melted. Subsequently, it is left standing for 12 minutes and an on-site rapid component analysis test is conducted. After the components are qualified, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A4.

[0021] Example 5 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentage of each component is: Si: 9.5 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.02 wt.%, La: 0.05 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0022] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10La master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 720 °C to melt pure aluminum, and then heated up to 755 °C to add Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys. After the master alloy is melted, the furnace is cooled down to 690 °C. The berger is used to push pure Mg into the bottom area of the crucible to melt it, and then it is stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, a refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and it is aerated for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. After the refining is completed, the Al-10La master alloy is pressed into the bottom area of the crucible using the berger to melt it, stirred for 5 minutes until it is completely melted, then left standing for 12 minutes, and an on-site rapid component analysis test is carried out. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the mold release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A5.

[0023] Example 6 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentage of each component is: Si: 9.5 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.02 wt.%, Ce: 0.05 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0024] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment and its die-casting process in this example include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10Ce master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 720 °C to melt pure aluminum, and then heated up to 755 °C to add Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys. After the master alloy is melted, the furnace is cooled down to 690 °C. The berger is used to push pure Mg into the bottom area of the crucible to melt it, and then it is stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and it is aerated for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is allowed to stand for 12 minutes and the slag removal treatment is completed. After the refining is completed, the Al-10Ce master alloy is pressed into the bottom area of the crucible using the berger to melt it, stirred for 5 minutes until completely melted, then allowed to stand for 12 minutes, and an on-site rapid component analysis test is conducted. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the mold release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A6.

[0025] Example 7 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentages of each component are: Si: 10 wt.%, Mg: 0.5 wt.%, Mn: 0.8 wt.%, Ti: 0.2 wt.%, Cu: 0.5 wt.%, V: 0.1 wt.%, La: 0.15 wt.%, Sr: 0.05 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0026] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10La master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum. Subsequently, Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. Using a bell jar, pure Mg is pushed into the bottom area of the crucible and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. After the refining is completed, using a bell jar, the Al-10La master alloy is pressed into the bottom area of the crucible and melted, stirred for 5 minutes until completely melted, then left standing for 12 minutes, and an on-site rapid component analysis test is carried out. After the components pass the test, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the mold release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A7.

[0027] Example 8 This example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentage of each component is: Si: 8 wt.%, Mg: 0.1 wt.%, Mn: 0.5 wt.%, Ti: 0.05 wt.%, Cu: 0.05 wt.%, V: 0.01 wt.%, La: 0.01 wt.%, Sr: 0.01 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0028] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10La master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum. Subsequently, Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloys are melted, the furnace is cooled down to 690 °C. Using a plunger, pure Mg is pushed into the bottom region of the crucible and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. After the refining is completed, using a plunger, the Al-10La master alloy is pressed into the bottom region of the crucible and melted, stirred for 5 minutes until completely melted, then left standing for 12 minutes, and an on-site rapid component analysis test is carried out. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The injection speed is 3 m / s, the casting pressure is 80 MPa, the mold release agent ratio is 1:100, and the mold temperature is 230 °C. The mold used in the production process is a die-cast test bar mold, and the obtained casting is denoted as A8.

[0029] Comparative Example 1 This comparative example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened without heat treatment. The weight percentage of each component is Si: 8.0 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0030] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened without heat treatment in this comparative example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, and Al-50Cu master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum. Subsequently, Al-10Ti, Al-50Cu, Al-10Mn, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. Pure Mg is pushed into the bottom region of the crucible using a bell jar and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, a refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. And a rapid in-situ component analysis test is carried out. After the components are qualified, high-pressure casting is carried out at 690 °C. The parameters of the die-casting process and the die-casting mold are the same as those in Example 1, and casting A9 is obtained.

[0031] Comparative Example 2 This comparative example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentage of each component is Si: 9.5 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0032] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this comparative example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, and Al-50Cu master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum. Subsequently, Al-10Ti, Al-50Cu, Al-10Mn, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. Pure Mg is pushed into the bottom area of the crucible using a bell jar and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. And a rapid component analysis test is carried out on-site. After the components are qualified, high-pressure casting is carried out at 690 °C. The parameters of the die-casting process and the die for die-casting are the same as those in Example 1, and casting A10 is obtained.

[0033] Comparative Example 3 This comparative example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentages of each component are: Si: 9.5 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.15 wt.%, La: 0.05 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0034] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this comparative example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10La master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum. Subsequently, Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloys are melted, the furnace is cooled down to 690 °C. Using a plunger, pure Mg is pushed into the bottom area of the crucible and melted, and then stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and aeration is carried out for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is left standing for 12 minutes and the slag removal treatment is completed. After the refining is completed, using a plunger, Al-10La master alloy is pressed into the bottom area of the crucible and melted, stirred for 5 minutes until completely melted, then left standing for 12 minutes, and an on-site rapid component analysis test is carried out. After the components pass the inspection, high-pressure casting is carried out at 690 °C. The parameters of the die-casting process and the die-casting mold are the same as those in Example 1, and casting A11 is obtained.

[0035] Comparative Example 4 This comparative example relates to a high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment. The weight percentages of each component are: Si: 9.5 wt.%, Mg: 0.25 wt.%, Mn: 0.6 wt.%, Ti: 0.15 wt.%, Cu: 0.15 wt.%, V: 0.02 wt.%, La: 0.2 wt.%, Sr: 0.025 wt.%, Fe: 0.12 wt.%. The total amount of other impurities is 0.3 wt.%, and the balance is Al.

[0036] The production of the high-strength and tough die-cast aluminum silicon alloy strengthened by non-heat treatment in this comparative example and its die-casting process include the following steps. 1) Drying: The prepared raw materials of pure aluminum, pure Si, pure Mg, Al-10Mn master alloy, Al-10Ti master alloy, Al-50Cu master alloy, Al-10La master alloy, and Al-5V master alloy are preheated to 200 °C and subjected to a drying treatment. 2) Smelting: The furnace is heated up to 755 °C to melt pure aluminum. Subsequently, Al-10Ti, Al-50Cu, Al-10Mn, Al-5V, and pure Si alloys are added. After the master alloy is melted, the furnace is cooled down to 690 °C. The plunger is used to push pure Mg into the bottom area of the crucible to melt it, and then it is stirred for 5 minutes. Subsequently, the melt is heated up to 720 °C, nitrogen gas with a pressure of 0.4 MPa is introduced into the melt, refining agent powder accounting for 0.4% of the total weight of the melt is introduced, and it is aerated for 10 minutes at a gas flow rate of 300 r / min and 0.5 sccm to remove slag and gas. Subsequently, it is allowed to stand for 12 minutes and the slag removal treatment is completed. After the refining is completed, the Al-10La master alloy is pressed into the bottom area of the crucible using the plunger to melt it, stirred for 5 minutes until it is completely melted, then allowed to stand for 12 minutes, and an on-site rapid component analysis test is conducted. After the components are qualified, high-pressure casting is carried out at 690 °C. The parameters of the die-casting process and the die for die-casting are the same as those in Example 1, and casting A12 is obtained.

[0037] The mechanical property tests were conducted on the castings A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, and A12 manufactured in Examples 1, 2, 3, 4, 5, 6, 7, 8 and Comparative Examples 1, 2, 3, 4 respectively, and the test results are shown in Table 1. Comparing the mechanical properties of the A1, A2, A3, and A9 castings, when the V element or the rare earth Er element is added alone, the strength and elongation rate of the alloy are significantly improved. The tensile strength is improved by up to 27 MPa, and the improvement range of the elongation rate reaches 24.1%. The improvement of the plasticity of the alloy by adding V and Er elements simultaneously is more remarkable. The elongation rate of the casting increases significantly from 8.7% (A9) to 14.9% (A3), and the amplification rate is 71.2%. Similarly, the above rules can be found by comparing the mechanical properties of the A4 and A10 castings. By adding V and Er elements in combination, the plasticity of the die-cast aluminum alloy with a high Si content (9.5 wt.%) is significantly improved, so that the elongation rate reaches from 6.5% (A10 casting) to 12.9% (A4 casting), meeting the characteristics of high strength and high toughness of the alloy. Comparing the mechanical properties of the A4, A5, A6, and A10 castings, the combined addition of V and rare earth elements such as Er, La, and Ce can significantly improve the plasticity and tensile strength of the die-cast aluminum alloy. Among them, the tensile strength of the A4 - A6 castings is ~281 MPa (the meaning of this symbol is about 281 MPa), and the elongation rate is ~12.8%, which is 16.5% and 97% higher than that of the A10 casting respectively. This explains that all three types of RE rare earths included in this patent have a significant effect on the alloy. Comparing the mechanical properties of the A5, A7, A8, A11, and A12 castings, within the alloy component range of this patent, the yield strength of the die-cast aluminum alloy is greater than 120 MPa, the tensile strength is greater than 260 MPa, and the elongation rate is greater than 10% (A5, A7, A8 castings) by adding V and rare earth elements in combination, reflecting the excellent mechanical properties of the alloy within the component range of this patent. When V reaches 0.15 (casting A11) or the rare earth element reaches 0.2 (casting A12) in the alloy and exceeds the patent range, the elongation rate and tensile strength of the alloy decrease significantly, especially the elongation rate drops below 8%, and a high-strength and high-toughness die-cast aluminum alloy material cannot be obtained.As described above, in the alloy composition range according to the present invention, by adding V element and RE elements (La, Er, Ce), the die-cast Al-Si alloy has the characteristics of high strength and high toughness in the non-heat-treated state. [Table 1]

[0038] Microstructure observations were performed on castings A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, and A12 produced in Examples 1-8 and Comparative Examples 1-4, respectively. Comparing the microstructures of A1(a), A2(b), A3(c), and A9(i) as shown in Figure 1, the addition of V and the rare earth element Er significantly refined the eutectic Si structure. In the absence of V and Er in the alloy, the eutectic Si in the casting exhibited a layered structure, as shown in Figure 1(i), with a grain size of approximately 4 μm. With the addition of V or Er, the eutectic Si structure transformed from layered to granular, and the grain size significantly decreased to 1 μm, as shown in Figures 1(a) and 1(b). With the combined addition of V and Er, the size of the eutectic Si in the structure further decreased, and the eutectic Si exhibited a finer, worm-like structure, as shown in Figure 1(c). Changes in microstructural features are closely related to changes in mechanical properties. Clearly, the introduction of V and Er significantly refines the eutectic Si structure and alters its morphology, significantly affecting the alloy's performance. A comparison of the A4 and A10 microstructures reveals that the combined effect of V and Er is equally effective for alloys with high Si content. For an alloy with a Si content of 9.5 wt% and no V or Er additions, the eutectic Si structure in the microstructure exhibits coarse, broken lines, the size of which can reach up to 10 μm (Fig. 1(j)). Meanwhile, with the addition of V and Er, the eutectic Si structure of the alloy is significantly refined to a worm-like shape (as shown in Fig. 1(d)), but the localization of square, blocky eutectic Si structures also impacts the alloy's plasticity. Therefore, the plasticity of the A3 alloy is superior to that of the A4 alloy. Comparing the A4, A5, A6, A7, A8, and A10 casting structures, it is clear that the addition of V in combination with Er, La, and Ce rare earth elements in the alloy range of this patent can eliminate the coarse, broken-line structure in die-cast aluminum alloys, thereby ensuring the performance of the alloy. Comparing the A5, A11, and A12 casting structures, it is clear that the addition of too much V element will cause the formation of a secondary phase of AlV in the alloy structure, and the addition of too many rare earth elements will cause the formation of a secondary phase of AlLa in the alloy, which will significantly reduce the plasticity of the alloy.Generally, the combined action of V and RE elements introduced into the patented alloy further disperses eutectic Si particles in the structure and greatly improves their morphology, and this structural feature endows the alloy with excellent mechanical properties.

[0039] The above are only examples of the present invention and do not limit the patent scope of the present invention. Transformations of equivalent structures or equivalent flows made using the specification of the present invention, or direct or indirect use in other related technical fields, are similarly included in the patent protection scope of the present invention.

Claims

1. A high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment, wherein the weight percentages of the respective components in the die-cast aluminum silicon alloy are: Si 8.0 - 10.0 wt.%, Mg 0.1 - 0.5 wt.%, Mn 0.5 - 0.8 wt.%, Cu 0.05 - 0.5 wt.%, Ti 0.05 - 0.2 wt.%, Sr 0.01 - 0.05 wt.%, V 0.01 - 0.1 wt.%, RE 0.01 - 0.15 wt.%, Fe < 0.2 wt.%, the total amount of other impurities is ≦ 0.4 wt.%, and the balance is Al. A high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment, characterized thereby.

2. The high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment according to claim 1, characterized in that the RE element contains one or more of La, Ce, and Er elements.

3. A method for manufacturing a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment according to claim 1, wherein the manufacturing method comprises: Drying: Preheating pure Al, pure Si, pure Mg, Al-Mn master alloy, Al-Ti master alloy, Al-Cu master alloy, Al-RE master alloy, and Al-V master alloy of the prepared raw materials, and performing a drying process in step S1; Smelting: After melting pure Al during the first temperature rise, adding Al-Ti master alloy, Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, and pure Si. After the master alloy melts, lower the temperature, press pure Mg into the bottom of the melt and melt it. After completely melting, raise the temperature of the alloy melt for the second time and refine it. Further, press the Al-RE master alloy into the bottom of the melt and melt it. After completely melting, let it stand to obtain a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment in step S2; A method for manufacturing a high-strength and high-toughness die-cast aluminum silicon alloy strengthened without heat treatment according to claim 1, characterized by including the above.

4. The manufacturing method according to claim 3, characterized in that the preheating temperature in step S1 is 190 - 210 °C.

5. The manufacturing method according to claim 3, characterized in that the temperature of the first temperature rise in step S2 is 750 °C - 760 °C.

6. The manufacturing method according to claim 3, characterized in that the temperature of the temperature drop in step S2 is 680 °C - 700 °C.

7. The manufacturing method according to claim 3, wherein the temperature of the second temperature increase in step S2 is 720 to 730 °C.

8. The refining in step S2 specifically comprises flowing nitrogen gas with a refining agent powder through the melt using a rotary spraying device to perform powder spraying refining, slag removal, and gas removal treatments, followed by standing for 10 to 15 minutes to complete the slag removal treatment and obtain a refined melt, which is characterized in that it is the manufacturing method according to claim 3.

9. The process parameters of the rotary spraying device are characterized in that the rotation speed for gas removal is 300 to 350 r / min, the gas removal time is 5 to 10 min, the pressure of the gas source during gas removal is 0.35 ± 0.05 MPa, and the gas flow rate is 0.2 to 0.8 sccm, which is the manufacturing method according to claim 8.

10. The refining agent used contains one of magnesium chloride and calcium chloride, which is characterized in that it is the manufacturing method according to claim 8.

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