High-Fe-tolerance aluminum alloy for extrusion casting and preparation method of high-Fe-tolerance aluminum alloy

Abstract

The invention relates to a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method of the high-Fe-tolerance aluminum alloy, belongs to the technical field of aluminum alloy pressure casting, and solves the problems of low Fe content tolerance in aluminum alloy production, low use proportion of recycled aluminum, low toughness of aluminum alloy products, complex heat treatment process and long period in the prior art. The invention discloses a high-Fe-tolerance aluminum alloy for squeeze casting. The high-Fe-tolerance aluminum alloy comprises the following components in percentage by mass: 2-4% of Si, 1-2% of Mg, 0.5-1.0% of Fe, 0.01-1.5% of microalloy elements and the balance of Al, the microalloy element is one or a mixture of more of Sr, Cr, Mn and Zr. And green low-energy-consumption casting of the high-toughness aluminum alloy is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy pressure casting, and in particular to a high Fe tolerance aluminum alloy for extrusion casting and a preparation method thereof. Background Art

[0002] Aluminum alloy has many advantages such as good comprehensive performance, excellent forming ability, ideal density, etc., so it is the most important lightweight metal material at present, and has a relatively mature set of technologies such as material system, forming process, manufacturing equipment, etc. In particular, cast aluminum alloy and its supporting technology, due to its forming advantages in complex structures, are widely used in the production and manufacturing of key and important components, especially in aerospace, rail transportation, automotive equipment and other fields where lightweighting is urgently needed.

[0003] However, with the continuous deepening of application scenarios, aluminum alloy components continue to develop towards large-scale, integrated, and complex. The innovative development direction of related technologies and materials is also in response to the above changes, such as large-scale integrated die-casting technology and equipment, high-strength and toughness heat-treatment-free materials, etc. One of the important development directions is to improve the purity of aluminum alloys, which puts forward higher requirements on material composition, especially the content of impurity elements.

[0004] Fe is an inevitable impurity element in cast aluminum alloys. Due to its extremely low solid solubility, it generally exists in the matrix in the form of plate-like multi-component compounds, which splits the matrix and causes a significant drop in component performance, especially elongation. At the same time, the presence of multi-component compounds will also consume strengthening elements, thereby reducing the overall performance of the material. Therefore, the current mainstream high-performance cast aluminum alloys have higher requirements for the Fe element. For example, the Fe content of the domestic ZL026 alloy is not higher than 0.15%, and the ZL206.2A alloy used to manufacture key components requires an Fe content of less than 0.07%. The Fe content of the high-strength and tough AM5 alloy developed by Russia does not exceed 0.3%, and the most widely used casting alloy A356.2 alloy has an Fe content of 0.2%. In addition, the heat-treatment-free aluminum alloys that have become a hot spot for research and development and use also have lower requirements for Fe content. For example, the Fe content of Alcoa's C611 alloy is 0.08-0.2%, the Fe content of Germany Rhine's Magsimal 59 series Al-Mg alloy is 0.2%, and the Al-Si alloy THAS-1 developed by Tsinghua University and First Automobile Group requires an Fe content of less than 0.2%.

[0005] However, Fe is an unavoidable alloying element in aluminum alloys. It will be introduced during the production process when it comes into contact with crucibles, molds, etc., and will continue to accumulate during recycling.

[0006] Due to the alloy's lower requirements for Fe content, the proportion of electrolytic aluminum used in the preparation of aluminum alloys increases, while the proportion of recycled aluminum used decreases. The production process of electrolytic aluminum consumes a lot of energy and cannot fully utilize the advantages of aluminum alloy recycling, which has a great impact on the green and low-carbon level of the overall production process. Summary of the invention

[0007] In view of the above analysis, an embodiment of the present invention aims to provide a high Fe tolerance aluminum alloy for extrusion casting and a preparation method thereof, so as to solve at least one of the problems of low Fe content tolerance in existing aluminum alloy production, low utilization ratio of recycled aluminum, low strength and toughness of aluminum alloy products, complex heat treatment process and long cycle.

[0008] On the one hand, an embodiment of the present invention provides a high Fe tolerance aluminum alloy for squeeze casting, wherein the alloy content is calculated by mass percentage as follows: Si: 2-4%, Mg: 1-2%, Fe: 0.5-1.0%, micro-alloying elements: 0.01-1.5%, and the balance is Al; the micro-alloying elements are a mixture of one or more of Sr, Cr, Mn and Zr.

[0009] Furthermore, the addition amount of the microalloying elements in the aluminum alloy is calculated as follows by mass percentage: Sr content 0.01-0.02%; and / or Cr content 0.2-0.4%; and / or Mn content 0.5-1.5%; and / or Zr content 0.3-0.8%.

[0010] On the other hand, an embodiment of the present invention further provides a method for preparing a high Fe tolerance aluminum alloy for squeeze casting, which is used for preparing the aluminum alloy, comprising the following steps:

[0011] Step 1, preparing the alloy according to the mass ratio of the alloy components;

[0012] Step 2: Place the prepared alloy into a furnace, raise the furnace temperature to the melting temperature, and melt the alloy into a molten alloy;

[0013] Step 3, introducing argon gas into the alloy melt, and then removing scum in the alloy melt;

[0014] Step 4, standing until the melt temperature drops to the pouring temperature;

[0015] Step 5, pouring the aluminum alloy melt into a barrel for extrusion casting to obtain a formed casting;

[0016] Step 6: Perform low temperature aging treatment on the formed casting to obtain an aluminum alloy component.

[0017] Preferably, the smelting temperature in step 2 is 760-780°C.

[0018] Furthermore, in step 3, the argon gas is introduced by rotary blowing at a rotation speed of 150-160r / min.

[0019] Specifically, the duration of the argon rotation blowing in step 3 is 20-25 minutes.

[0020] Exemplarily, the pouring temperature in step 4 is 725-745°C.

[0021] Furthermore, the pressure of the extrusion casting in step 5 is 120-150 MPa, the mold temperature during extrusion casting is 230-250° C., the low injection speed is 4-5 mm / s, and the injection time is 20-30 s.

[0022] It is worth noting that the low-temperature short-time aging treatment process in step 6 is to keep warm at 120-130°C for 1-2 hours.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] 1. Different from the prior art, the present invention provides a high Fe tolerance aluminum alloy, which adjusts the type of iron-rich phase crystals through the coordinated regulation of alloying elements, greatly reduces the splitting and stress concentration of the matrix, and thus ensures the comprehensive performance of aluminum alloy parts. Compared with the existing requirement for low Fe content in aluminum alloys, the present invention allows a more relaxed Fe content and can ensure good strength, toughness and forming properties of aluminum alloys, thereby allowing a higher proportion of recycled aluminum to be used in the production process, reducing production costs, improving material utilization, optimizing the level of green recycling, and overall promoting the production process to meet the requirements of green and low-carbon development.

[0025] 2. The present invention adjusts the crystal type of the iron-rich phase through the coordinated regulation of Mg and microalloying elements, wherein the addition of Mg reduces the reaction temperature, reduces the growth rate of the iron-rich phase, and obtains a smaller geometric size; when Mn is added, since the size of Mn atoms is similar to that of Fe atoms, it is easy to replace the iron atoms in the iron-rich phase, so that the iron-rich phase is transformed from a needle-like β iron-rich phase to a blocky α iron-rich phase; when Cr is added, the solid solubility of Cr in the iron-rich phase is much greater than that in the aluminum matrix, thereby inhibiting the growth of the iron-rich phase and inhibiting the growth of the iron-rich phase along the preferred growth direction; when Sr or Zr elements are added, Sr and Zr elements are easy to be enriched around the iron-rich phase, inhibiting the diffusion of iron atoms and promoting the isotropic growth of the iron-rich phase; Mg, Mn, Cr, Sr, Zr and other elements are added in combination, wherein Mn and Cr can replace Fe atoms in the iron-rich phase, and Mg, Sr and Zr can change the thermodynamic equilibrium, so that the iron-rich phase is transformed from a plate-like shape with obvious preferred orientation to an isotropic block, such as Figure 2 As shown in the figure, the bright white iron-rich phase is obviously thickened and shortened, and the average size is reduced, which greatly reduces the cracking and stress concentration on the matrix.

[0026] 3. The present invention reduces the presence of eutectic Si phase by reducing the Si element content, which is beneficial to avoid it as a heterogeneous nucleation point at a special position to promote the preferential nucleation and growth of the iron-rich phase, and inhibit the formation of local large-sized iron-rich phase; utilizes the higher forming pressure of the extrusion casting process to force the aluminum liquid to punch the mold, reduces the requirements for the intrinsic flow characteristics of the aluminum alloy, and realizes the preparation of heat-treatment-free aluminum alloy at a lower Si element content.

[0027] 4. The present invention optimizes the targeted material system through innovation, combined with the process characteristics of high-pressure assisted solidification forming in extrusion casting, applies high pressure to drive the liquid melt in the core to flow and compensate for shrinkage after the shell of the casting solidifies, and forms a strong shear force under the hindrance of the solidification structure, thereby achieving the crushing and refinement of the iron-rich phase, avoiding the formation and existence of large-sized plate-like iron-rich phases, and finally obtaining significant grain refinement, especially the refinement of the multi-component iron-rich phase; on the basis of ensuring the good strength and toughness and forming characteristics of the aluminum alloy, a more relaxed Fe element content is allowed, thereby allowing a higher proportion of recycled aluminum to be used in the production process, reducing production costs, improving material utilization, optimizing the green recycling level, and promoting the production process as a whole to meet the development requirements of green and low-carbon.

[0028] 5. The present invention develops an appropriate low-temperature short-time heat treatment process, which can effectively avoid the performance degradation caused by the coarsening of the iron-rich phase while eliminating the forming stress and improving the dimensional stability of the parts; the performance can reach tensile strength>300MPa, yield strength>206MPa, elongation after fracture>7%, and the comprehensive performance is good. It can be used as a heat-treatment-free alloy in the production and manufacturing of large-sized complex structural parts.

[0029] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0031] Figure 1 Typical microstructure of the high Fe tolerance alloy for squeeze casting of the present invention Figure 1 ;

[0032] Figure 2 Typical microstructure of the high Fe tolerance alloy for squeeze casting of the present invention Figure 2 ;

[0033] Figure 3 Typical microstructure of the high Fe tolerance alloy for squeeze casting of the present invention Figure 3 . DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0035] On the one hand, a specific embodiment of the present invention discloses a high Fe tolerance aluminum alloy for squeeze casting, wherein the alloy content is calculated by mass percentage as follows: Si: 2-4%, Mg: 1-2%, Fe: 0.5-1.0%, micro-alloying elements: 0.01-1.5%, and the balance is Al; the micro-alloying elements are a mixture of one or more of Sr, Cr, Mn and Zr.

[0036] The microalloying elements Sr, Cr, Mn and Zr can be added to the alloy alone or in any combination to adjust the morphology of the iron-rich phase in the alloy.

[0037] Furthermore, the addition amount of the microalloying elements in the aluminum alloy is calculated as follows by mass percentage: Sr content 0.01-0.02%; and / or Cr content 0.2-0.4%; and / or Mn content 0.5-1.5%; and / or Zr content 0.3-0.8%.

[0038] In a possible design, the types and mass percentages of microalloying elements added to the aluminum alloy are: Mn: 1-1.2%, Sr: 0.012-0.02%;

[0039] In a possible design, the types and mass percentages of microalloying elements added to the aluminum alloy are: Mn: 0.5-1%, Cr: 0.3-0.4%, Sr: 0.015-0.02%;

[0040] In a possible design, the types and mass percentages of the added micro-alloying elements in the aluminum alloy are: Mn: 0.8-1%, Sr: 0.018-0.02%, Zr: 0.3-0.5%.

[0041] The following is a detailed description of the effects and dosage of the components in the present invention:

[0042] Si: increases fluidity, but too high Si content will affect the toughness of aluminum alloy. The preferred Si content is 2-4%.

[0043] Mg: Combined with Si to form Mg2Si phase, it improves the toughness of aluminum alloy and reduces the liquidus temperature. The preferred Mg content is 1-2%.

[0044] Mn: adjusts the morphology of the iron-rich phase and improves the mechanical properties of the alloy. However, too much Mn content will make the iron-rich phase coarse and segregate, affecting the properties of the alloy. The preferred Mn content is 0.5-1.5%.

[0045] Sr: changes the thermodynamic equilibrium and reduces the preferential growth trend of the iron-rich phase. Too much Sr will cause the iron-rich phase to grow into thick needles or flowers. The preferred Sr content is 0.01-0.02%.

[0046] Cr: regulates the size and morphology of the iron-rich phase and improves the mechanical properties of the alloy. Too much Cr will reduce the formability of the alloy. The preferred Cr content is 0.2-0.4%.

[0047] Zr: Increases nucleation rate, reduces the size of the iron-rich phase, and high content increases material cost. The preferred Zr content is 0.3-0.8%.

[0048] Figure 1 This is a typical structure of a squeeze casting high Fe tolerance aluminum alloy prepared by the technical method of the present invention, wherein the main dark part is the Al matrix in the form of equiaxed grains, and the bright part is the iron-rich phase.

[0049] On the other hand, a specific embodiment of the present invention discloses a method for preparing a high Fe tolerance aluminum alloy for squeeze casting, comprising the following steps:

[0050] Step 1, preparing the alloy according to the mass ratio of the alloy components;

[0051] Step 2: Place the prepared alloy into a furnace, raise the furnace temperature to the melting temperature, and melt the alloy into a molten alloy;

[0052] Step 3, introducing argon gas into the alloy melt, and then removing scum in the alloy melt;

[0053] Step 4, standing until the melt temperature drops to the pouring temperature;

[0054] Step 5, pouring the aluminum alloy melt into a barrel for extrusion casting to obtain a formed casting;

[0055] Step 6: Perform low temperature aging treatment on the formed casting to obtain an aluminum alloy component.

[0056] Preferably, the smelting temperature in step 2 is 760-780°C. Specifically, the smelting temperature is 760°C, 770°C, or 780°C.

[0057] Exemplarily, the argon gas is introduced in step 3 by rotary blowing at a rotation speed of 150-160 r / min.

[0058] Specifically, the duration of the argon rotation blowing in step 3 is 20-25 minutes.

[0059] During aluminum alloy smelting, hydrogen in the aluminum melt accounts for more than 85% of the total gas volume, and hydrogen will precipitate to form pinholes when the aluminum solidifies. The introduction of argon gas can effectively replace the hydrogen in the aluminum melt, reduce the hydrogen content in the aluminum melt, and thus improve the mechanical properties of the aluminum alloy; through the rotary blowing method, the argon gas can be broken into tiny bubbles, and the bubbles will take away the hydrogen and slag in the aluminum liquid during the rising process, thereby achieving the purpose of purifying the aluminum liquid.

[0060] Furthermore, the pouring temperature in step 4 is 725-745° C. Exemplarily, the pouring temperature is 725° C., 735° C., or 745° C.

[0061] It is worth noting that the pressure of the extrusion casting in step 5 is 120-150 MPa, the mold temperature during extrusion casting is 230-250°C, the injection speed is 4-5 mm / s, and the injection time is 20-30 s. Preferably, the pressure of the extrusion casting is 120 MPa, the mold temperature during extrusion casting is 230°C, the injection speed is 4 mm / s, and the injection time is 20 s.

[0062] If the mold temperature is too low, it will lead to difficulties in product molding, defects such as weld lines and rough product surface, and cause casting holes and cold wall defects; if the mold temperature is too high, it will lead to surface bubbles, sticking, shrinkage holes and other defects in the casting, and the mold life will be reduced.

[0063] Reasonable injection speed helps the aluminum alloy melt to flow evenly and discharge gas, reducing bubbles and impurities inside the casting. If the injection speed is too fast, too much gas may be mixed into the aluminum liquid, thus forming defects such as pores in the casting. Appropriate injection pressure helps to fill and compensate for the aluminum liquid and enhance the density of the casting.

[0064] The high-pressure die of squeeze casting drives the alloy melt to flow, thus forming a fluid shearing effect in the solid-liquid chaotic zone, achieving the crushing and refinement of solidified dendrites and iron-rich phases and remelting spheroidization, and finally obtaining significant grain refinement, especially the refinement of multi-element iron-rich phases. The size of the iron-rich phase reaches about 10μm, such as Figure 3 As shown, ensuring the product has good strength and toughness levels.

[0065] Furthermore, the low temperature short aging treatment process in step 6 is to keep the temperature at 120-130°C for 1-2 hours. Preferably, the aging treatment process is to keep the temperature at 120°C for 1 hour.

[0066] Since the iron-rich phase cannot be dissolved back at high temperature, and when the aging temperature is too high, the precipitated phase loses its coherent relationship with the matrix, the elastic coherent strain disappears, and the strength of the alloy begins to decrease, that is, over-aging occurs. If the aging temperature is too low, the dynamics are insufficient, resulting in a long aging time and reduced process efficiency. Therefore, an appropriate low-temperature and short-time heat treatment process is developed to eliminate the forming stress and improve the dimensional stability of the parts while effectively avoiding the performance degradation caused by the coarsening of the iron-rich phase; the performance can reach tensile strength>300MPa, yield strength>206MPa, and elongation>7%. The comprehensive performance is good, the process is simple, and the cycle is short, so that it can be used as a heat-treatment-free alloy in the production and manufacturing of large-size complex structural parts.

[0067] In summary, through the coordinated regulation of alloying elements such as Mg, Mn, Cr, Sr, and Zr, it is possible to obtain complex structural aluminum alloy components with good strength and toughness under high Fe content conditions by using extrusion casting technology combined with low-temperature short-aging process. In addition, a higher proportion of recycled aluminum can be used in the production process, thereby reducing production costs, improving material utilization, optimizing the level of green recycling, and overall promoting the production process to meet the development requirements of green and low-carbon.

[0068] The high Fe tolerance aluminum alloy for squeeze casting and the preparation method thereof of the present invention are described below with reference to specific embodiments.

[0069] Example 1

[0070] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0071] The mass ratios of the alloy elements are: Si: 4%, Mg: 2%, Fe: 0.8%, Mn: 1%, Sr: 0.02%, and the balance is Al.

[0072] The specific preparation steps are as follows:

[0073] Step 1: Prepare the alloy according to the mass ratio of alloy components;

[0074] Step 2: Place the prepared alloy into the furnace and raise the furnace temperature to 780°C;

[0075] Step 3: After the alloy is melted, argon gas is introduced into the alloy melt by means of rotary blowing for 20 minutes at a speed of 150 r / min, and then the slag in the alloy melt is removed;

[0076] Step 4: Stand still until the melt temperature drops to 735°C;

[0077] Step 5: Pour the aluminum alloy melt into the barrel for extrusion casting, with a pressure of 150 MPa, a mold temperature of 230 ° C, an injection speed of 4 mm / s, and an injection time of 20 s;

[0078] Step 6: Perform low-temperature aging treatment on the formed casting by keeping it at 120° C. for 1 hour to obtain an aluminum alloy part.

[0079] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0080] Example 2

[0081] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0082] The mass ratios of the alloy elements are: Si: 2%, Mg: 1%, Fe: 0.8%, Mn: 1%, Sr: 0.02%, and the balance is Al.

[0083] The specific preparation steps are as follows:

[0084] Step 1: Prepare the alloy according to the mass ratio of alloy components;

[0085] Step 2: Place the prepared alloy into the furnace and raise the furnace temperature to 780°C;

[0086] Step 3: After the alloy is melted, argon gas is introduced into the alloy melt by means of rotary blowing for 20 minutes at a speed of 150 r / min, and then the slag in the alloy melt is removed;

[0087] Step 4: Stand still until the melt temperature drops to 725°C;

[0088] Step 5: Pour the aluminum alloy melt into the barrel for extrusion casting, with a pressure of 150 MPa, a mold temperature of 230 ° C, an injection speed of 4 mm / s, and an injection time of 20 s;

[0089] Step 6: Perform low-temperature aging treatment on the formed casting by keeping it at 120° C. for 1 hour to obtain an aluminum alloy part.

[0090] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0091] Example 3

[0092] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0093] The mass ratios of the alloy elements are: Si: 4%, Mg: 2%, Fe: 0.8%, Mn: 1%, Cr: 0.4%, Sr: 0.02%, and the balance is Al.

[0094] The specific preparation steps are as follows:

[0095] Step 1: Prepare the alloy according to the mass ratio of alloy components;

[0096] Step 2: Place the prepared alloy into the furnace and raise the furnace temperature to 780°C;

[0097] Step 3: After the alloy is melted, argon gas is introduced into the alloy melt by means of rotary blowing for 20 minutes at a speed of 150 r / min, and then the slag in the alloy melt is removed;

[0098] Step 4: Stand still until the melt temperature drops to 735°C;

[0099] Step 5: Pour the aluminum alloy melt into the barrel for extrusion casting, with a pressure of 150 MPa, a mold temperature of 230 ° C, an injection speed of 4 mm / s, and an injection time of 20 s;

[0100] Step 6: Perform low-temperature aging treatment on the formed casting by keeping it at 120° C. for 1 hour to obtain an aluminum alloy part.

[0101] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0102] Example 4

[0103] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0104] The mass ratios of the alloy elements are: Si: 4%, Mg: 2%, Fe: 0.8%, Mn: 1%, Sr: 0.02%, and the balance is Al.

[0105] The specific preparation steps are as follows:

[0106] Step 1: Prepare the alloy according to the mass ratio of alloy components;

[0107] Step 2: Place the prepared alloy into the furnace and raise the furnace temperature to 780°C;

[0108] Step 3: After the alloy is melted, argon gas is introduced into the alloy melt by means of rotary blowing for 20 minutes at a speed of 150 r / min, and then the slag in the alloy melt is removed;

[0109] Step 4: Stand still until the melt temperature drops to 735°C;

[0110] Step 5: Pour the aluminum alloy melt into the barrel for extrusion casting, with a pressure of 120 MPa, a mold temperature of 230 ° C, an injection speed of 5 mm / s, and an injection time of 20 s;

[0111] Step 6: Perform low-temperature aging treatment on the formed casting by keeping it at 130° C. for 1 hour to obtain an aluminum alloy part.

[0112] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0113] Example 5

[0114] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0115] The mass ratios of the alloy elements are: Si: 4%, Mg: 2%, Fe: 0.8%, Mn: 1%, Sr: 0.02%, Zr: 0.3%, and the balance is Al.

[0116] The specific preparation steps are as follows:

[0117] Step 1: Prepare the alloy according to the mass ratio of alloy components;

[0118] Step 2: Place the prepared alloy into the furnace and raise the furnace temperature to 780°C;

[0119] Step 3: After the alloy is melted, argon gas is introduced into the alloy melt by means of rotary blowing for 20 minutes at a speed of 150 r / min, and then the slag in the alloy melt is removed;

[0120] Step 4: Stand still until the melt temperature drops to 735°C;

[0121] Step 5: Pour the aluminum alloy melt into the barrel for extrusion casting, with a pressure of 150 MPa, a mold temperature of 230 ° C, an injection speed of 4 mm / s, and an injection time of 20 s;

[0122] Step 6: Perform low-temperature aging treatment on the formed casting by keeping it at 120° C. for 1 hour to obtain an aluminum alloy part.

[0123] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0124] Comparative Example 1

[0125] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0126] The mass ratios of the alloy elements are: Si: 4%, Mg: 2%, Fe: 0.2%, Sr: 0.02%, and the balance is Al.

[0127] The specific preparation steps are the same as those in Example 1.

[0128] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0129] Comparative Example 2

[0130] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0131] The mass ratios of the alloy elements are: Si: 4%, Fe: 0.8%, Mn: 1%, and the balance is Al.

[0132] The specific preparation steps are the same as those in Example 1.

[0133] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0134] Comparative Example 3

[0135] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0136] The mass ratio of alloy elements is the same as that in Example 1.

[0137] The specific preparation steps are basically the same as those in Example 1, except that the low-temperature aging treatment in step 6 is not performed.

[0138] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0139] Comparative Example 4

[0140] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0141] The mass ratio of alloy elements is the same as that in Example 1.

[0142] The specific preparation steps are basically the same as those in Example 1, except that step 5 adopts a high-pressure die-casting method, specifically: pouring the molten aluminum alloy into the barrel for high-pressure die-casting, the pressure is 35 MPa, the mold temperature is 230°C, the injection speed is 4 m / s, and the injection time is 0.5 s.

[0143] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0144] Comparative Example 5

[0145] This embodiment provides a gravity cast aluminum alloy and a preparation method thereof.

[0146] The mass ratio of alloy elements is the same as that in Example 1.

[0147] The specific preparation steps are as follows:

[0148] Step 1: Prepare the alloy according to the mass ratio of alloy components;

[0149] Step 2: Place the prepared alloy into the furnace and raise the furnace temperature to 780°C;

[0150] Step 3: After the alloy is melted, argon gas is introduced into the alloy melt by means of rotary blowing for 20 minutes at a speed of 150 r / min, and then the slag in the alloy melt is removed;

[0151] Step 4: Pour the molten aluminum alloy into the mold for gravity casting;

[0152] Step 5: subject the formed casting to low temperature aging treatment at 120°C for 1 hour.

[0153] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0154] Comparative Example 6

[0155] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0156] The mass ratios of the alloy elements are: Si: 7%, Mg: 2%, Fe: 0.8%, Mn: 1%, Sr: 0.02%, and the balance is Al.

[0157] The specific preparation steps are the same as those in Example 1.

[0158] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0159] Comparative Example 7

[0160] This embodiment provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

[0161] The mass ratio of alloy elements is the same as that in Example 1.

[0162] The specific preparation steps are basically the same as those in Example 1, except that the argon gas treatment in step 3 is not performed.

[0163] The mechanical properties of the aluminum alloy parts are shown in Table 1.

[0164] Table 1 Comparison of mechanical properties of test bars prepared in Example and Comparative Example

[0165] serial number Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 310±5 220±5 8.9±0.9 Example 2 305±5 210±4 9.4±0.6 Example 3 304±3 211±5 7.2±0.2 Example 4 306±1 210±3 7.6±0.3 Example 5 313±3 225±3 9.5±0.5 Comparative Example 1 300±11 190±8 11.0±0.5 Comparative Example 2 200±7 170±10 9.8±0.6 Comparative Example 3 270±12 170±6 10.3±0.5 Comparative Example 4 210±5 140±3 1.5±0.5 Comparative Example 5 240±6 150±4 3.5±1.1 Comparative Example 6 312±6 218±4 4.5±0.8 Comparative Example 7 212±10 160±7 1.5±1.2

[0166] It can be intuitively shown by comparison in Table 1 that the high Fe content alloys prepared by the technology of Examples 1 to 5 using the present invention have basically the same strength and toughness as the low Fe content alloy (Comparative Example 1) under the same process, and are slightly improved in tensile strength and yield strength, which significantly demonstrates the high Fe tolerance advantage of the present invention; and compared with the alloys with the same Fe content but different Mg content prepared by the same process (Comparative Example 2), the tensile strength and yield strength prepared by the technology of the present invention are greatly improved; compared with the alloy without short aging treatment (Comparative Example 3), the tensile strength and yield strength of the treated alloy are improved to a certain extent, and the elongation after fracture remains basically unchanged.

[0167] The high Fe tolerance alloy involved in the present invention has a significant attenuation in mechanical properties, especially elongation after fracture, under the process conditions of high pressure die casting (Comparative Example 4) and gravity casting (Comparative Example 5). Squeeze casting completes the filling, solidification, crystallization and shrinkage feeding processes under pressure, and forms a strong shear force under the hindrance of solidification structure, thereby achieving the crushing and refinement of the iron-rich phase, and allowing a looser Fe content on the basis of ensuring good strength and toughness and forming characteristics of the aluminum alloy.

[0168] In Comparative Example 6, the toughness of the aluminum alloy is significantly reduced due to the excessively high Si content.

[0169] In Comparative Example 7, since argon gas was not introduced for replacement during the alloy smelting process, the hydrogen content in the aluminum melt was too high, resulting in a significant decrease in the mechanical properties of the aluminum alloy.

[0170] In summary, through the coordinated regulation of alloying elements such as Mg, Mn, Cr, Sr, and Zr, it is possible to obtain complex structural aluminum alloy components with good strength and toughness under high Fe content conditions by using extrusion casting technology combined with low-temperature short-aging process. In addition, a higher proportion of recycled aluminum can be used in the production process, thereby reducing production costs, improving material utilization, optimizing the level of green recycling, and overall promoting the production process to meet the development requirements of green and low-carbon.

[0171] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A high Fe tolerance aluminum alloy for squeeze casting, characterized in that: The alloy content is calculated by mass percentage as follows: Si: 2-4%, Mg: 1-2%, Fe: 0.5-1.0%, micro-alloy elements: 0.01-1.5%, and the balance is Al; the micro-alloy elements are a mixture of one or more of Sr, Cr, Mn and Zr.

2. The aluminum alloy according to claim 1, characterized in that The addition amount of the microalloying elements in the aluminum alloy is calculated by mass percentage as follows: Sr content 0.01-0.02%; and / or Cr content 0.2-0.4%; and / or Mn content 0.5-1.5%; and / or Zr content 0.3-0.8%.

3. A method for preparing a high Fe tolerance aluminum alloy for squeeze casting, characterized in that: The method for preparing the aluminum alloy according to claim 1 or 2 comprises the following steps: Step 1, preparing the alloy according to the mass ratio of the alloy components; Step 2: Place the prepared alloy into a furnace, raise the furnace temperature to the melting temperature, and melt the alloy into a molten alloy; Step 3, introducing argon gas into the alloy melt, and then removing scum in the alloy melt; Step 4, standing until the melt temperature drops to the pouring temperature; Step 5, pouring the aluminum alloy melt into a barrel for extrusion casting to obtain a formed casting; Step 6: Perform low temperature aging treatment on the formed casting to obtain a high Fe tolerance aluminum alloy.

4. The preparation method according to claim 3, characterized in that: The smelting temperature in step 2 is 760-780°C.

5. The preparation method according to claim 3, characterized in that: In step 3, the argon gas is introduced by rotary blowing at a rotation speed of 150-160r / min.

6. The preparation method according to claim 5, characterized in that: The duration of the argon gas rotary blowing in step 3 is 20-25 minutes.

7. The preparation method according to claim 3, characterized in that: The pouring temperature in step 4 is 725-745°C.

8. The preparation method according to claim 3, characterized in that: The pressure of the extrusion casting in step 5 is 120-150 MPa, the injection speed is 4-5 mm / s, and the injection time is 20-30 s.

9. The preparation method according to claim 8, characterized in that: The mold temperature used during extrusion casting is 230-250℃.

10. The preparation method according to claim 3, characterized in that: The low temperature short aging treatment process in step 6 is to keep the temperature at 120-130° C. for 1-2 hours.

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