High fe tolerance aluminum alloy for squeeze casting and method of manufacturing the same

Abstract

The present application relates to a kind of high Fe tolerance aluminum alloy for squeeze casting and its preparation method, belong to aluminum alloy pressure casting technical field, solve the low Fe content tolerance in prior art in the production of aluminum alloy, the low proportion of recycled aluminum use, the problem of not high high-toughness performance of aluminum alloy product, heat treatment process is complex, long cycle.A kind of high Fe tolerance aluminum alloy for squeeze casting, alloy content is as follows according to percentage by mass:Si:2-4%, Mg:1-2%, Fe:0.5-1.0%, microalloying element:0.01-1.5%, the balance is Al;The microalloying element is one or more mixtures of Sr, Cr, Mn and Zr.It realizes high-toughness green low-energy consumption casting of aluminum alloy.

Description

TECHNICAL FIELD

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

[0002] Aluminum alloy has many advantages such as good comprehensive performance, excellent forming ability, ideal density, etc., and is currently the most important lightweight metal material, and has a relatively mature material system, forming process, manufacturing equipment and complete technology. In particular, casting aluminum alloy and its supporting technology have been widely used in the production and manufacturing of key components due to their forming advantages in complex structures, especially in the fields of aerospace, rail transportation, automobile equipment and other fields that urgently need lightweight.

[0003] However, with the continuous deepening of application scenarios, aluminum alloy parts continue to develop towards large-scale, integration and complexity, and the development direction of related technology and materials is also in response to the above changes, such as large-scale integrated die casting technology and equipment, high-strength and high-toughness heat treatment-free materials, etc. One important development direction is to improve the purity of aluminum alloy, i.e. higher requirements are put forward for the composition of the material, especially the content of impurity elements.

[0004] Fe element, as a major impurity element in cast aluminum alloy, has extremely low solid solubility and generally exists in the form of platelet-shaped multi-element compound in the matrix, thereby cutting the matrix and causing a substantial decrease in the elongation of the component. At the same time, the existence of multi-element compounds also consumes strengthening elements, thereby reducing the overall performance of the material. Therefore, the current mainstream high-performance cast aluminum alloy puts forward higher requirements for Fe element, such as the domestic ZL026 alloy with Fe content not higher than 0.15%, the ZL206.2A alloy used to manufacture key components with Fe content lower than 0.07%, the high-strength AM5 alloy developed by Russia with Fe content not more than 0.3%, the most widely used cast alloy A356.2 alloy with Fe content of 0.2%, in addition, the heat treatment-free aluminum alloy which has become a research and use hotspot also puts forward lower requirements for Fe content, such as the C611 alloy of American Aluminum Industry with Fe content of 0.08-0.2%, the Magsimal 59 series Al-Mg alloy of Germany Rhein with Fe content of 0.2%, and the Al-Si series alloy THAS-1 developed by Tsinghua University and the First Automobile Group with Fe content lower than 0.2%.

[0005] However, Fe element, as an unavoidable alloying element in aluminum alloy, is introduced in the production process of contact with crucible, mold, etc., and continuously accumulates in the recycling process.

[0006] Due to the low requirement of the alloy on the content of Fe element, the proportion of electrolytic aluminum used in the preparation of the aluminum alloy is increased, and the proportion of recycled aluminum used is reduced. However, the production process of electrolytic aluminum has high energy consumption, and cannot fully play the advantage of recycling of the aluminum alloy, which has a great influence on the green and low-carbon level of the overall production process. SUMMARY

[0007] In view of the above analysis, the embodiments of the present application aim 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 in the prior art, such as low Fe content tolerance of the aluminum alloy, low proportion of recycled aluminum, low strength and toughness of the aluminum alloy product, and complex and long period of heat treatment process.

[0008] In one aspect, the embodiments of the present application provide a high Fe tolerance aluminum alloy for extrusion casting, the alloy content is as follows in terms of mass percentage: Si: 2-4%, Mg: 1-2%, Fe: 0.5-1.0%, micro-alloying element: 0.01-1.5%, and the balance is Al; the micro-alloying element is one or a mixture of more than one of Sr, Cr, Mn and Zr.

[0009] Further, the addition amount of the micro-alloying element in the aluminum alloy is as follows in terms of 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] In another aspect, the embodiments of the present application also provide a preparation method of a high Fe tolerance aluminum alloy for extrusion casting, which is used for the preparation of the aluminum alloy, and includes the following steps:

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

[0012] Step 2, placing the configured alloy into a furnace, raising the furnace temperature to a smelting temperature, and melting the alloy into an alloy melt;

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

[0014] Step 4, standing until the temperature of the melt is reduced to a pouring temperature;

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

[0016] Step 6, performing low-temperature aging treatment on the shaped casting to obtain an aluminum alloy part.

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

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

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

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

[0021] Furthermore, in step 5, the pressure of the extrusion casting is 120-150 MPa, the mold temperature is 230-250℃, the 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-aging process described in step 6 involves holding the temperature at 120-130℃ 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. Unlike existing technologies, this invention provides a high-Fe-tolerance aluminum alloy. Through the synergistic regulation of alloying elements, the type of iron-rich phase crystals is adjusted, significantly reducing the cracking and stress concentration on the matrix, thereby ensuring the comprehensive performance of the aluminum alloy parts. Compared to existing requirements for low Fe content in aluminum alloys, this invention allows for a more flexible Fe content while ensuring good strength, toughness, and formability of the aluminum alloy. This allows for a higher proportion of recycled aluminum to be used in the production process, reducing production costs, improving material utilization, optimizing green recycling levels, and overall promoting the production process to meet the requirements of green and low-carbon development.

[0025] 2. This invention achieves adjustment of the iron-rich phase crystal type through the synergistic regulation of Mg and microalloying elements. The addition of Mg lowers the reaction temperature, reduces the growth rate of the iron-rich phase, and results in a smaller geometric size. When Mn is added, because the atomic size of Mn is similar to that of Fe, it easily replaces iron atoms in the iron-rich phase, transforming it 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 its solid solubility in the aluminum matrix, thereby inhibiting the growth of the iron-rich phase and preventing it from growing along its preferred growth direction. When Sr or Zr is added, Sr and Zr easily accumulate around the iron-rich phase, inhibiting the diffusion of iron atoms and promoting isotropic growth of the iron-rich phase. The combined addition of Mg, Mn, Cr, Sr, and Zr allows Mn and Cr to replace Fe atoms in the iron-rich phase, while Mg, Sr, and Zr can alter the thermodynamic equilibrium, transforming the iron-rich phase from a plate-like structure with a distinct preferred orientation to an isotropic blocky structure. Figure 2 As shown, the bright white iron-rich phase is significantly thickened and shortened, with a reduced average size, which greatly reduces the cutting effect on the matrix and stress concentration.

[0026] 3、The present application reduces the existence of eutectic Si phase by reducing the content of Si element, which is beneficial to avoid its promotion of preferential nucleation and growth of iron-rich phase as a heterogeneous nucleation point in a special position, and inhibits the formation of local large-size iron-rich phase; the higher forming pressure of the extrusion casting process is used to forcibly drive the liquid aluminum to fill the mold, which reduces the requirement for the intrinsic flow characteristics of aluminum alloy, and realizes the preparation of heat treatment-free aluminum alloy under a lower Si element content.

[0027] 4、The present application realizes the crushing and refinement of iron-rich phase, avoids the formation and existence of large-size plate-shaped iron-rich phase, and finally obtains significant grain refinement, especially the refinement of multi-element iron-rich phase, by applying high pressure to drive the core liquid melt to flow forcibly after the shell of the casting is solidified, under the hindering effect of the solidification structure, so that a strong shearing force is formed.

[0028] 5、The present application develops a proper low-temperature short-time heat treatment process, which can effectively avoid the performance degradation caused by the coarsening of iron-rich phase while eliminating forming stress and improving the size stability of the part; the performance can reach tensile strength > 300 MPa, yield strength > 206 MPa, and elongation after fracture > 7%, and the comprehensive performance is good, so that the heat treatment-free alloy can be applied to the production and manufacturing of large-size complex structural parts.

[0029] The above technical solutions in the present application can also be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the present application. The purposes and other advantages of the present application can be realized and obtained from the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated herein and constitute a part of the detailed description. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application. In the drawings:

[0031] Figure 1 Typical microstructure of the extrusion casting high Fe tolerance alloy of the present application Figure 1 ;

[0032] Figure 2 Typical microstructure of the extrusion casting high Fe tolerance alloy of the present application Figure 2 ;

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

[0034] The preferred embodiments of the present application will be described in detail with reference to the drawings, in which:

[0035] In one aspect, one embodiment of the present application discloses a high Fe tolerance aluminum alloy for squeeze casting, the alloy contains, by mass percentage, Si: 2-4%, Mg: 1-2%, Fe: 0.5-1.0%, micro-alloying elements: 0.01-1.5%, and the balance of Al; the micro-alloying elements are one or a mixture of more than one of Sr, Cr, Mn and Zr.

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

[0037] Further, the micro-alloying elements are added to the aluminum alloy in the following mass percentages: 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 one possible design, the types and mass percentages of micro-alloying elements added to the aluminum alloy are: Mn: 1-1.2%, Sr: 0.012-0.02%;

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

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

[0041] The effects and dosage selection of the components contained in the present application are described in detail as follows:

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

[0043] Mg: combines with Si to form Mg2Si phase to improve the strength and toughness of the aluminum alloy, while reducing the liquidus temperature. The preferred Mg content is 1-2%.

[0044] Mn: adjust the morphology of iron-rich phase, improve the mechanical properties of the alloy, but excessive Mn content will make the iron-rich phase become coarse and segregation, affecting the performance of the alloy. Preferably, the Mn content is 0.5-1.5%.

[0045] Sr: change the thermodynamic equilibrium, reduce the preferential growth trend of iron-rich phase, and excessive Sr will cause the iron-rich phase to grow into coarse needle-like or flower-like. Preferably, the Sr content is 0.01-0.02%.

[0046] Cr: control the size and morphology of the iron-rich phase, improve the mechanical properties of the alloy, and excessive Cr element will reduce the formability of the alloy. Preferably, the Cr content is 0.2-0.4%.

[0047] Zr: increase the nucleation rate, reduce the size of the iron-rich phase, and high content increases the cost of the material. Preferably, the Zr content is 0.3-0.8%.

[0048] Figure 1 The typical organization of the extrusion casting high Fe tolerance aluminum alloy prepared by the technical method of the present application, wherein the main dark part is Al matrix in equiaxed grain shape, and the high bright part is iron-rich phase.

[0049] In another aspect, one embodiment of the present application discloses a preparation method of an extrusion casting high Fe tolerance aluminum alloy, comprising the following steps:

[0050] Step 1, configuring the alloy according to the mass ratio of alloy composition;

[0051] Step 2, placing the configured alloy into a furnace, raising the furnace temperature to a melting temperature, and melting the alloy into an alloy melt;

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

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

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

[0055] Step 6, performing low-temperature aging treatment on the shaped casting to obtain an aluminum alloy part.

[0056] Preferably, the melting temperature in step 2 is 760-780℃. Specifically, the melting temperature is 760℃, 770℃, 780℃.

[0057] Exemplarily, the way of introducing argon in step 3 is rotary blowing, and the rotating speed is 150-160r / min.

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

[0059] The hydrogen in the aluminum melt accounts for more than 85% of the total amount of gas when the aluminum alloy is smelted, and the hydrogen is precipitated to form pinholes when the aluminum solidifies. The 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 rotating blowing mode, the argon gas can be blown into fine bubbles, and the hydrogen and dross in the aluminum liquid are taken away in the rising process, so as to achieve the purpose of purifying the aluminum liquid.

[0060] Further, the pouring temperature in step 4 is 725-745℃. For example, the pouring temperature is 725℃, 735℃, or 745℃.

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

[0062] If the mold temperature is too low, the product forming will be difficult, and defects such as welding lines and rough product surface will occur, resulting in casting hole and cold wall defects. If the mold temperature is too high, the casting will be prone to surface bubbles, sticking, shrinkage, and other defects, and the service life of the mold will be reduced.

[0063] A reasonable injection speed is helpful for the uniform flow of the aluminum alloy melt and the discharge of gas, and reduces the bubbles and impurities in the casting. If the injection speed is too fast, too much gas may be mixed into the aluminum liquid, thereby forming pores and other defects in the casting. A proper injection pressure is helpful for the filling and shrinkage of the aluminum liquid, and enhances the density of the casting.

[0064] The extrusion casting high-pressure forming drive makes the alloy melt flow forcibly, thereby forming fluid shear in the solid-liquid chaotic zone, realizing the fragmentation and remelting spheroidization of the solidification dendrites and iron-rich phase, and finally obtaining significant grain refinement, especially the refinement of the multi-element iron-rich phase, and the size of the iron-rich phase reaches about 10μm, as shown in FIG. 1, which ensures a good strength and toughness level of the product. Figure 3

[0065] Further, the low-temperature short-time aging treatment process in step 6 is 120-130℃ for 1-2h. Preferably, the aging treatment process is 120℃ for 1h.

[0066] ​Since the high-temperature re-dissolution of the iron-rich phase cannot be achieved, and when the aging temperature is too high, the precipitated phase loses the coherent relationship with the matrix, the elastic coherent strain disappears, and the strength of the alloy begins to decrease, that is, overaging occurs, and when the aging temperature is too low, the kinetics is insufficient, resulting in a long aging time, and the process efficiency is reduced, therefore, developing an appropriate low-temperature short-time heat treatment process 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 part; the performance can reach tensile strength > 300 MPa, yield strength > 206 MPa, and elongation after fracture > 7%, the comprehensive performance is good, the process is simple, and the cycle is short, so as to be applied to the production and manufacturing of large-size complex structural parts as a heat treatment-free alloy.

[0067] In summary, through the synergistic regulation of alloying elements such as Mg, Mn, Cr, Sr, and Zr, under the condition of a high Fe content, an aluminum alloy part with good strength and toughness performance is obtained by using an extrusion casting technology combined with a low-temperature short-time aging process, and a higher proportion of recycled aluminum is allowed to be used in the production process, thereby reducing production costs, improving material utilization, optimizing the green recycling level, and overall promoting the production process to meet the development requirements of green and low carbon.

[0068] The high-Fe-tolerance aluminum alloy for extrusion casting and the preparation method thereof will be described below in combination with specific examples.

[0069] Example 1

[0070] The present embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

[0071] The mass ratio of the alloying elements is as follows: 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: configure the alloy according to the mass ratio of the alloy composition;

[0074] Step 2: place the configured alloy into a furnace, and raise the furnace temperature to 780℃;

[0075] Step 3: after the alloy is melted, argon is introduced into the alloy melt in a rotary spraying manner for 20 min at a speed of 150 r / min, and then the dross in the alloy melt is removed;

[0076] Step 4: wait until the melt temperature drops to 735℃;

[0077] Step 5: pour the aluminum alloy melt into a barrel for extrusion casting, the pressure is 150 MPa, the mold temperature is 230℃, the injection speed is 4 mm / s, and the injection time is 20 s;

[0078] Step 6: the shaped casting is subjected to low-temperature aging treatment at 120℃ for 1h to obtain the aluminum alloy part.

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

[0080] Embodiment 2

[0081] The embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

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

[0083] The specific preparation steps are as follows:

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

[0085] Step 2: placing the configured alloy into a furnace and raising the furnace temperature to 780℃;

[0086] Step 3: after the alloy is melted, argon is introduced into the alloy melt in a rotary spraying manner for 20min at a rotating speed of 150r / min, and then the dross in the alloy melt is removed;

[0087] Step 4: standing until the melt temperature drops to 725℃;

[0088] Step 5: pouring the aluminum alloy melt into a barrel for extrusion casting, the pressure is 150MPa, the mold temperature is 230℃, the injection speed is 4mm / s, and the injection time is 20s;

[0089] Step 6: the shaped casting is subjected to low-temperature aging treatment at 120℃ for 1h to obtain the aluminum alloy part.

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

[0091] Embodiment 3

[0092] The embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

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

[0094] The specific preparation steps are as follows:

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

[0096] Step 2: Put the prepared alloy into the furnace, and raise the temperature to 780℃;

[0097] Step 3: After the alloy is melted, introduce argon into the alloy melt in a rotary spraying manner for 20 min at a rotating speed of 150 r / min, and then remove the dross in the alloy melt;

[0098] Step 4: Keep still until the temperature of the melt is reduced to 735℃;

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

[0100] Step 6: Perform low-temperature aging treatment on the formed casting at 120℃ for 1 h to obtain an aluminum alloy part.

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

[0102] Example 4

[0103] The embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

[0104] The mass ratio of the alloying elements is: 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 the alloying elements;

[0107] Step 2: Put the prepared alloy into the furnace, and raise the temperature to 780℃;

[0108] Step 3: After the alloy is melted, introduce argon into the alloy melt in a rotary spraying manner for 20 min at a rotating speed of 150 r / min, and then remove the dross in the alloy melt;

[0109] Step 4: Keep still until the temperature of the melt is reduced to 735℃;

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

[0111] Step 6: Perform low-temperature aging treatment on the formed casting at 130℃ for 1 h to obtain an aluminum alloy part.

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

[0113] Example 5

[0114] The embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

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

[0116] The specific preparation steps are as follows:

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

[0118] Step 2: placing the configured alloy into a furnace, and improving the furnace temperature to 780 DEG C;

[0119] Step 3: after the alloy is melted, argon is introduced into the alloy melt in a rotary spraying mode for 20 min, the rotating speed is 150 r / min, and then the dross in the alloy melt is removed;

[0120] Step 4: standing until the melt temperature is reduced to 735 DEG C;

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

[0122] Step 6: subjecting the formed casting to 120 DEG C heat preservation for 1 h low-temperature aging treatment, and obtaining an aluminum alloy part.

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

[0124] Comparative Example 1

[0125] The embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

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

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

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

[0129] Comparative Example 2

[0130] The embodiment provides a high-Fe-tolerance aluminum alloy for extrusion casting and a preparation method thereof.

[0131] The mass ratio of alloy elements is as follows: Si: 4%, Fe: 0.8%, Mn: 1%, and the balance being Al.

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

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

[0134] Comparative Example 3

[0135] The present example provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

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

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

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

[0139] Comparative Example 4

[0140] The present example provides a high Fe tolerance aluminum alloy for squeeze casting and a preparation method thereof.

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

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

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

[0144] Comparative Example 5

[0145] The present example provides a gravity casting aluminum alloy and a preparation method.

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

[0147] The specific preparation steps are as follows:

[0148] Step 1: configure the alloy according to the mass ratio of alloying elements;

[0149] Step 2: put the configured alloy into the furnace and raise the furnace temperature to 780℃;

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

[0151] Step 4: pour the aluminum alloy melt into the mold for gravity casting;

[0152] Step 5: The shaped casting is subjected to a low-temperature aging treatment at 120℃ for 1h.

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

[0154] Comparative Example 6

[0155] The present embodiment provides a high Fe tolerance aluminum alloy for extrusion casting and a preparation method thereof.

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

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

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

[0159] Comparative Example 7

[0160] The present embodiment provides a high Fe tolerance aluminum alloy for extrusion casting and a preparation method thereof.

[0161] The mass ratios of alloying elements are the same as those in Example 1.

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

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

[0164] Table 1 Comparison of mechanical properties of test bars prepared in examples and comparative examples

[0165] 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] As can be directly observed from Table 1, the high Fe content alloy prepared by the present technology in Examples 1-5 has basically the same performance as the low Fe content alloy prepared under the same process (Comparative Example 1), and slightly improved tensile strength and yield strength, which demonstrates the high Fe tolerance advantage of the present application. Compared with the same Fe content but different Mg content alloy prepared under the same process (Comparative Example 2), the tensile strength and yield strength of the alloy prepared by the present technology are greatly improved. Compared with the alloy without short-term 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 is basically unchanged.

[0167] The present application relates to high Fe tolerance alloy, under the condition of high pressure die casting (comparative example 4) and gravity casting (comparative example 5) process, the obtained force performance, especially the elongation after fracture appears a substantial attenuation. Extrusion casting completes filling, solidification crystallization and feeding process under the action of pressure, under the hindering effect of solidification structure, forms strong shear force, thereby realizing the crushing and refinement of iron-rich phase, on the basis of ensuring good strength and toughness of aluminum alloy and forming characteristics, allows more relaxed Fe content.

[0168] Comparative example 6 due to the content of Si element is too high, the toughness of aluminum alloy is significantly reduced.

[0169] Comparative example 7 due to not passing argon gas for replacement in the alloy smelting process, the hydrogen content in the aluminum melt is too high, causing the mechanical properties of aluminum alloy to decrease significantly.

[0170] In summary, through the synergistic regulation of Mg, Mn, Cr, Sr, Zr and other alloy elements, under the condition of higher Fe content, the extrusion casting technology is used to obtain complex structure aluminum alloy parts with good strength and toughness performance by using low temperature short aging process, and higher proportion of recycled aluminum is allowed in the production process, thereby reducing the production cost, improving the material utilization rate, optimizing the green cycle level, and promoting the production process to meet the development requirements of green and low carbon.

[0171] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A high Fe tolerance extrusion cast aluminum alloy characterized by, The alloy content is as follows in percentage by mass: Si: 2-4%, Mg: 1-2%, Fe: 0.8-1.0%, micro-alloying elements: 1.02-1.5%, and the balance of Al; the micro-alloying elements are one or more of Sr, Cr, Mn and Zr; The preparation is carried out by the following method: Step 1, configuring the alloy according to the mass ratio of alloy components; Step 2, putting the configured alloy into a furnace, raising the furnace temperature to a smelting temperature, and melting the alloy into an alloy melt; Step 3, introducing argon into the alloy melt, and then removing the dross in the alloy melt; Step 4, standing until the melt temperature drops to a pouring temperature; Step 5, pouring the aluminum alloy melt into a barrel for extrusion casting, the pressure of the extrusion casting is 120-150 MPa, the injection speed is 4-5 mm / s, the injection time is 20-30 s, and a shaped casting is obtained; Step 6, performing low-temperature aging treatment on the shaped casting, the low-temperature short-term aging treatment process is 120-130℃ for 1-2 h, and a high Fe tolerance aluminum alloy is obtained; The typical microstructure of the high Fe tolerance extrusion cast aluminum alloy includes a main Al matrix and a blocky iron-rich phase, the Al matrix is in equiaxed grain shape, and the iron-rich phase has a size of 10 μm; wherein Mn adjusts the morphology of the iron-rich phase, improves the mechanical properties of the alloy, Sr changes the thermodynamic equilibrium, reduces the preferential growth trend of the iron-rich phase, Cr controls the size and morphology of the iron-rich phase, improves the mechanical properties of the alloy, Zr increases the nucleation rate and reduces the size of the iron-rich phase, extrusion casting high-pressure impact molding drives the alloy melt to flow forcibly, thereby forming fluid shear in the solid-liquid chaotic zone, realizing the fragmentation and remelting spheroidization of the solidification dendrites and the iron-rich phase, and the size of the iron-rich phase reaches 10 μm; The high Fe tolerance extrusion cast aluminum alloy has a tensile strength > 300 MPa, a yield strength > 206 MPa, and an elongation after fracture > 7%.

2. The high Fe tolerance extrusion cast aluminum alloy of claim 1, wherein, The micro-alloying element addition amount in the aluminum alloy is as follows in percentage by mass: 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 of producing a high Fe tolerance extrusion cast aluminum alloy, characterized by, The aluminum alloy preparation of claim 1 or 2 comprises the following steps: Step 1, configuring the alloy according to the mass ratio of alloy components; Step 2, putting the configured alloy into a furnace, raising the furnace temperature to a smelting temperature, and melting the alloy into an alloy melt; the smelting temperature is 760-780℃; Step 3, introducing argon into the alloy melt, and then removing the dross in the alloy melt; Step 4, standing until the melt temperature drops to a pouring temperature; Step 5, pouring the aluminum alloy melt into a barrel for extrusion casting, the pressure of the extrusion casting is 120-150 MPa, the injection speed is 4-5 mm / s, the injection time is 20-30 s, and a shaped casting is obtained; Step 6, performing low-temperature aging treatment on the shaped casting, the low-temperature short-term aging treatment process is 120-130℃ for 1-2 h, and a high Fe tolerance extrusion cast aluminum alloy is obtained.

4. The production method according to claim 3, characterized by, The argon introduction mode in step 3 is rotary blowing, and the rotation speed is 150-160 r / min.

5. The preparation method according to claim 4, characterized in that, The argon gas spin spraying time in Step 3 is 20-25 min.

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

7. The preparation method according to claim 3, characterized in that, The mold temperature used in the squeeze casting is 230-250°C.

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