High-fatigue-resistance and high-toughness aluminum alloy forge piece and preparation method thereof

Abstract

The invention provides a high-fatigue-resistance and high-toughness aluminum alloy forge piece and a preparation method thereof, and relates to the technical field of aluminum alloy materials. The aluminum alloy forge piece with high fatigue resistance and high strength and toughness comprises the following components in percentage by weight: 7.0%-8.5% of Zn, 1.4%-2.3% of Mg, 1.6%-2.4% of Cu, 0.01%-0.04% of Cr, 0.01%-0.04% of Mn, 0.08%-0.15% of Zr + Sc, less than or equal to 0.04% of Si, less than or equal to 0.06% of Fe and the balance of Al and inevitable impurities, and the total content of the impurities is less than or equal to 0.1%. The maximum use thickness of the aluminum alloy forge piece can break through the limit of 152 mm, and compared with 7050 and 7085 alloys of the same specification, the strength is improved by 5% or above, and meanwhile the equivalent toughness level is kept; and particularly, the anti-fatigue performance is outstanding, the fatigue limit is improved by 25% or above compared with that under the condition that the stress R is equal to-1, and the requirement of future aviation equipment for the high-comprehensive-performance aluminum alloy material is met.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy materials, and in particular to a high-fatigue-resistance and high-strength and toughness aluminum alloy forging and a preparation method thereof. Background Art

[0002] Helicopters face complex load environments during flight, and their rotor systems are subjected to millions of high-frequency alternating loads during each flight. This long-term accumulated fatigue damage becomes a key factor limiting the service life of the aircraft. Compared with fixed-wing aircraft, helicopter materials must not only have traditional high specific strength properties, but also meet more stringent fatigue resistance requirements. For key metal materials in helicopters, the fatigue limit (R=-1) index requirements are clearly defined in the material standards. For new aluminum alloy materials, the smooth fatigue limit requirement exceeds σ -1 ≥190MPa.

[0003] Currently, international aviation equipment primarily utilizes aluminum alloys such as 7050, 7085, and 7475. These materials have been successfully used in the manufacture of forgings and hot-rolled plates for advanced fighter aircraft such as the F-35, F-22, and Rafale M. Although my country has achieved domestic production of 7050 and 7085 aluminum alloys, significant gaps remain in key performance indicators: when the material thickness exceeds 152mm, its high-cycle fatigue limit under the R=-1 stress state only reaches approximately 150MPa, making it difficult to meet the long-term service requirements of the new generation of helicopters in the harsh environments. Although the 7055 aluminum alloy developed through high-alloying can increase the fatigue limit to over 190MPa, its insufficient hardenability limits its maximum applicable thickness to less than 70mm, making it unsuitable for the manufacture of large, integral components in aviation equipment. Therefore, the development of a new, highly fatigue-resistant aluminum alloy suitable for large thickness specifications is of great significance. Summary of the Invention

[0004] In response to the above problems, the present invention provides a high fatigue resistance and high strength and toughness aluminum alloy forging and a preparation method thereof, which ensures that the aluminum alloy material has good high strength, toughness and high fatigue resistance when the thickness is above 150mm.

[0005] To solve the above technical problems, in a first aspect, the present invention provides a high fatigue resistance and high strength and toughness aluminum alloy forging, wherein the aluminum alloy forging comprises the following components by weight percentage: Zn: 7.0%-8.5%, Mg: 1.4%-2.3%, Cu: 1.6%-2.4%, Cr: 0.01%-0.04%, Mn: 0.01%-0.04%, Zr+Sc: 0.08%-0.15%, Si≤0.04%, Fe≤0.06%, and the balance is Al and unavoidable impurities, with a total impurity content of ≤0.1%; Among them, when the Sc content is greater than 0.05%, the Zr+Sc content is less than 0.09%; when the Sc content is less than 0.02%, the Zr+Sc content is greater than 0.14%; when the Sc content is 0.02%-0.05%, the Zr+Sc content is 0.09%-0.14%.

[0006] The present invention appropriately increases the Zn content on the basis of the 7150 alloy, while reducing the Cu and Mg contents on the basis of the 7055 and 7056 alloys, and optimizes the Zn / Mg ratio and the Zn / Cu ratio. On the one hand, this ensures a high-density and uniform distribution of η' phase and T phase strengthening precipitation phases, providing an excellent strength foundation for the material; on the other hand, it effectively reduces the quenching sensitivity of the alloy, so that the material can still maintain a uniform microstructure and stable mechanical properties during the preparation process of large-thickness cross-sections above 150 mm.

[0007] The present invention synergistically refines the grains through the compounding of Zr and Sc elements with specific contents. The addition of Zr forms a stable dispersed phase, which effectively pins the grain boundaries and inhibits the recrystallization process; while the introduction of Sc further refines the grain structure and significantly improves the grain boundary strength by forming an Al3 (Sc, Zr) composite phase, which not only reduces the proportion of recrystallized grain boundaries, but also optimizes the distribution state of the precipitated phase at the grain boundaries, thereby improving the toughness and fatigue resistance of the material while increasing its strength.

[0008] In a second aspect, the present invention provides a method for preparing a high fatigue resistance and high toughness aluminum alloy forging, comprising the following steps: S1. Using high-purity aluminum, industrial-purity zinc, high-purity magnesium, high-purity electrolytic copper, Al-Zr master alloy and Al-Sc master alloy as raw materials, after melting treatment, refining treatment and casting treatment, controlling the content of each element to achieve the requirements of the high fatigue resistance and high toughness aluminum alloy forgings to obtain an ingot; S2. The ingot is subjected to a multi-stage homogenization heat treatment, and the homogenized ingot is heated and forged to obtain a billet; S3. The billet is heated and then subjected to die forging, followed by solution quenching treatment, cold pressing deformation treatment and multi-stage aging treatment in sequence to obtain the high fatigue resistance and high strength and toughness aluminum alloy forging.

[0009] Preferably, in step S1, the smelting temperature is 720-760°C.

[0010] Preferably, in step S1, the refining temperature is 720-740°C.

[0011] Preferably, in step S1, the casting temperature is 730-750°C, and the casting speed is 40-100 mm / min.

[0012] Preferably, in step S1, the ingot is a square ingot with a thickness of 320-460 mm or a round ingot with a diameter of 300-600 mm.

[0013] Preferably, in step S1, the melting and refining treatment is as follows: first, high-purity aluminum is added to a smelting furnace, completely melted at 720-760°C and then slag is removed, then industrial pure zinc, high-purity magnesium, high-purity electrolytic copper and Al-Zr master alloy are added, and after all the alloy elements are melted, stirring and sampling are performed to adjust the composition; the aluminum alloy melt is passed through an inert gas at 720-740°C for refining, slag is removed after refining, and secondary refining is performed after the sample composition is tested and qualified.

[0014] Preferably, in step S2, the multi-stage homogenization heat treatment is: first, keeping warm at 420-450°C for 10-14 hours, then keeping warm at 460-498°C for 18-24 hours, and finally keeping warm at 450-470°C for 6-12 hours.

[0015] Preferably, in step S2, the forging treatment is: heating the homogenized ingot at a heating temperature of 400-460°C and a holding time of 6-10h, and then performing 3-4 upsetting and 3-4 drawing deformation processes on the heated ingot, wherein the upsetting speed is ≤15mm / s, the reduction amount during the drawing process is ≤70mm, and the drawing distance is ≤30mm.

[0016] Preferably, in step S3, during the die forging process, the heating temperature of the blank is 400-440°C, the insulation time of the blank is 4-10 hours, and the use temperature of the mold is ≥250°C.

[0017] Preferably, in step S3, the solution quenching treatment is: first, keeping at 440-465°C for 2-6 hours, then keeping at 470-485°C for 3-7 hours, and then immediately water quenching, the quenching temperature is 35-60°C, and the quenching transfer time does not exceed 25 seconds.

[0018] Preferably, in step S3, the deformation amount in the cold pressing deformation treatment is 2%-6%.

[0019] Preferably, in step S3, the multi-stage aging treatment is: first, keeping warm at 100-120°C for 4-9 hours, and then keeping warm at 145-160°C for 11-28 hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The aluminum alloy forgings provided by this invention exceed the maximum usable thickness limit of 152mm. Compared with 7050 and 7085 alloys of the same specifications, their strength is increased by over 5% while maintaining comparable toughness. They demonstrate particularly outstanding fatigue resistance, with the fatigue limit at a stress ratio R = -1 increased by over 25%, meeting the demand for high-performance aluminum alloys for future aviation equipment. Furthermore, a comprehensive forging and heat treatment process has been developed. Through precise control of forging parameters and a multi-stage heat treatment system, the material's structural uniformity and performance stability across thick sections are ensured, ensuring the technical conditions for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A physical image of the stepped plate forging provided in Example 1 of the present invention (maximum thickness 250 mm); Figure 2 Actual photo of the boss plate forging provided in Example 2 of the present invention (maximum thickness is 210 mm). DETAILED DESCRIPTION

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the specific implementation methods will be briefly introduced below. Obviously, the embodiments described below are some implementation methods of the present invention. For ordinary technicians in this field, other implementation methods can be obtained based on these embodiments without paying creative work.

[0023] If specific experimental steps or conditions are not specified in the examples, the procedures or conditions of conventional experimental steps described in the literature in the field can be followed. All raw materials and instruments used are commercially available, including but not limited to those used in the examples of this application.

[0024] Example 1 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, whose designed composition, calculated by weight percentage, is: Zn: 8.4wt.%, Mg: 1.7wt.%, Cu: 1.9wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Sc: 0.02wt.%, Zr: 0.1wt.%, Si: 0.02 wt.%, Fe: 0.04 wt.%, the total impurity content is ≤0.1%, and the balance is Al. This embodiment provides a method for preparing a high fatigue resistance and high toughness aluminum alloy forging, comprising the following steps: (1) High-purity aluminum ingots (aluminum content exceeding 99.9%), high-purity electrolytic copper (GB / T 467-2010), Al-Zr5 master alloy, Al-Sc master alloy, industrial pure zinc (Zn content exceeding 99.9%), and high-purity magnesium (Mg content exceeding 99.92%) are selected as raw materials, and AlTi5B0.2 is selected as the refining agent. The melting temperature is set at 740-750℃. First, the high-purity aluminum ingot is melted. After the slag is completely melted, high-purity electrolytic copper, Al-Zr5 master alloy, Al-Sc master alloy, industrial pure zinc and high-purity magnesium are added. Electromagnetic field and ultrasonic vibration stirring technology are used as auxiliary. After sampling and testing the composition, the sample is transferred to the holding furnace and filled with high-purity nitrogen and argon mixed gas for refining. The refining temperature is 730℃. After the sample composition is tested after the slag is removed and it is qualified, Al-Ti5-B0.2 wire is added and secondary refining is carried out under high-purity nitrogen and argon mixed gas. After filtering and removing the slag, the casting process is carried out. The casting temperature is set at 740-750° C. and the casting speed is 50-60 mm / min to obtain a square ingot with a thickness of 460 mm.

[0025] (2) The square ingot obtained in step (1) was subjected to a multi-stage homogenization treatment, firstly kept at 430°C for 12 hours, then kept at 475°C for 20 hours, and finally kept at 450°C for 8 hours; after the treatment was completed, it was cooled to room temperature and milled, with a single-side removal of 15 mm.

[0026] (3) heating the ingot treated in step (2) to a temperature of 430°C, a holding time of 500 min, and an ingot transfer time not exceeding 180 min, and performing three upset and three drawing deformation processes on the heated ingot to obtain a billet, wherein the upset speed is ≤15 mm / s, the reduction amount during the drawing process is ≤70 mm, and the delivery distance is ≤30 mm.

[0027] (4) Using a split-type step-cavity mold, first preheat the mold to 390°C and keep it warm for 32 hours. After the mold is installed and debugged, check the mold cavity surface temperature to ensure that the operating temperature is ≥250°C. The blank obtained in step (3) is kept at 430°C for 12 hours and then precision die forged. During the pressing process, the die forging is quickly lowered to a distance of 100 mm from the parting surface. The pressing rate is changed to 1 mm / s, and the pressing is continued until the set pressing amount is reached to ensure that the material fully fills the mold cavity.

[0028] (5) The forgings after step (4) were subjected to solution treatment at a solution temperature of 445°C for 4 hours, and then to water quenching immediately after being heated at 480°C for 5 hours. The quenching temperature was controlled at 60°C, and cold pressing was performed immediately after quenching. The deformation was 5%. Within 48 hours after cold pressing, multi-stage aging treatment was carried out. The temperature was first kept at 100°C for 8 hours, and then kept at 160°C for 23 hours. After the aging was completed, the plate was air-cooled to room temperature to obtain a stepped plate forging with a maximum thickness of 250 mm.

[0029] Example 2 The difference between this embodiment and Example 1 is that, calculated by weight percentage, the designed composition is: Zn: 8.1 wt.%, Mg: 1.9 wt.%, Cu: 1.7 wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Sc: 0.02 wt.%, Zr: 0.1 wt.%, Si: 0.02 wt.%, Fe: 0.04 wt.%, the total impurity content is ≤0.1%, and the balance is Al.

[0030] This embodiment provides a method for preparing a high fatigue resistance and high toughness aluminum alloy forging, comprising the following steps: (1) High-purity aluminum ingots (aluminum content exceeding 99.9%), high-purity electrolytic copper (GB / T 467-2010), Al-Zr5 master alloy, Al-Sc master alloy, industrial pure zinc (Zn content exceeding 99.9%), and high-purity magnesium (Mg content exceeding 99.92%) are selected as raw materials, and AlTi5B0.2 is selected as the refining agent. The melting temperature is set at 720-730℃. First, the high-purity aluminum ingot is melted. After the slag is completely melted, high-purity electrolytic copper, Al-Zr5 master alloy, Al-Sc master alloy, industrial pure zinc and high-purity magnesium are added. Electromagnetic field and ultrasonic vibration stirring technology are used as auxiliary. After sampling and testing the composition, the sample is transferred to the holding furnace and filled with high-purity nitrogen and argon mixed gas for refining. The refining temperature is 740℃. After the sample composition is tested after the slag is removed and it is qualified, Al-Ti5-B0.2 wire is added and secondary refining is carried out under high-purity nitrogen and argon mixed gas. After filtering and removing the slag, the casting process is carried out. The casting temperature is set at 740-750° C. and the casting speed is 50-60 mm / min to obtain a square ingot with a thickness of 460 mm.

[0031] (2) The square ingot obtained in step (1) was subjected to a multi-stage homogenization treatment, firstly kept at 440°C for 10 h, then kept at 480°C for 18 h, and finally kept at 460°C for 10 h; after the treatment was completed, it was cooled to room temperature and milled, with a single-side removal of 15 mm.

[0032] (3) heating the ingot treated in step (2) to a temperature of 430°C, a holding time of 720 min, and an ingot transfer time not exceeding 180 min, and performing three upset and three drawing deformation processes on the heated ingot to obtain a billet, wherein the upset speed is ≤15 mm / s, the reduction amount during the drawing process is ≤70 mm, and the delivery distance is ≤30 mm.

[0033] (4) Using a special die for boss structure, first preheat the die to 390℃ and keep it warm for 32h. After the die is installed and debugged, check the surface temperature of the die cavity to ensure that the operating temperature is ≥250℃. The blank obtained in step (3) is kept at 430℃ for 12h and then precision die forged. During the pressing process, the die forging is quickly lowered to a distance of 100mm from the parting surface. The pressing rate is changed to 0.8mm / s and the pressing is continued until the set pressing amount is reached to ensure that the material fully fills the die cavity. The boss part is locally pressurized to 120% of the final pressure and the pressure is maintained for 10s to ensure a clear outline.

[0034] (5) The forgings after the treatment in step (4) were subjected to solution treatment at a solution temperature of 455°C for 3 hours, and then to water quenching immediately after being heated at 470°C for 6 hours. The quenching temperature was controlled at 60°C, and cold pressing was performed immediately after quenching. The deformation was 4%. Multi-stage aging treatment was carried out within 48 hours after cold pressing. The temperature was first heated at 100°C for 8 hours, and then heated at 150°C for 20 hours. After the aging was completed, the plate was air-cooled to room temperature to obtain a boss plate forging with a maximum thickness of 210 mm.

[0035] Example 3 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, whose designed composition, calculated by weight percentage, is: Zn: 8.4wt.%, Mg: 1.7wt.%, Cu: 1.9wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Sc: 0.01wt.%, Zr: 0.144wt.%, Si: 0.02 wt.%, Fe: 0.04 wt.%, the total impurity content is ≤0.1%, and the balance is Al.

[0036] The method for preparing the high fatigue resistance and high strength and toughness aluminum alloy forgings provided in this embodiment refers to Example 1.

[0037] Example 4 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, whose designed composition, calculated by weight percentage, is: Zn: 8.4wt.%, Mg: 1.7wt.%, Cu: 1.9wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Sc: 0.04wt.%, Zr: 0.05wt.%, Si: 0.02 wt.%, Fe: 0.04 wt.%, the total impurity content is ≤0.1%, and the balance is Al.

[0038] The method for preparing the high fatigue resistance and high strength and toughness aluminum alloy forgings provided in this embodiment refers to Example 1.

[0039] Example 5 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, and the design composition refers to Example 1.

[0040] The method for preparing high fatigue resistance and high strength and toughness aluminum alloy forgings provided in this embodiment refers to Example 1. The difference from Example 1 is that in step (1), the melting, refining and casting process parameters are different. The specific steps are as follows: The smelting temperature is set at 720-740°C. First, a high-purity aluminum ingot is melted. After complete melting, the slag is skimmed off. Various alloy ingots and master alloys are added, and electromagnetic field and ultrasonic vibration stirring technology are used. After sampling and testing for qualified components, the ingot is transferred to a holding furnace and filled with high-purity mixed gas for refining at a refining temperature of 730-740°C. After skimming and sampling, the components are tested to be qualified. Al-Ti5-B1 ​​wire is added and secondary refining is carried out under high-purity mixed gas. After filtering and removing the slag, the ingot is cast at a casting temperature of 725-735°C and a casting speed of 60-70 mm / min to obtain a square ingot with a formed thickness of 420 mm. Other aspects are the same as in Example 1.

[0041] Example 6 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, and the design composition refers to Example 1.

[0042] The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging provided in this embodiment refers to Example 1. The difference from Example 1 is that in step (1), the casting speed is 70-80 mm / min, and a square ingot with a formed thickness of 360 mm is obtained. Other processes are the same as in Example 1.

[0043] Example 7 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, and the design composition refers to Example 1.

[0044] The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging provided in this embodiment refers to that in embodiment 1, the casting speed is 80-100 mm / min, and a round ingot with a formed diameter of 400 mm is obtained. Other aspects are the same as in embodiment 1.

[0045] Example 8 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, and the design composition refers to Example 1.

[0046] The method for preparing high fatigue resistance and high strength and toughness aluminum alloy forgings provided in this embodiment refers to Example 1. The difference from Example 1 is that in step (2), the multi-stage homogenization treatment process parameters are different. The specific steps are as follows: The square ingot obtained in step (1) was subjected to a multi-stage homogenization treatment, first at 440°C for 10 hours, then at 485°C for 18 hours, and finally at 470°C for 6 hours. After the treatment, it was cooled to room temperature and milled, with a single-side removal of 15 mm. Other aspects were the same as in Example 1.

[0047] Example 9 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, and the design composition refers to Example 1.

[0048] The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging provided in this embodiment refers to Example 1. The difference from Example 1 is that in step (4), the die forging process parameters are different. The specific steps are as follows: First, preheat the mold to 350°C and keep it warm for 32 hours. After the mold is installed and debugged, check the mold cavity surface temperature to ensure that the operating temperature is ≥ 250°C. After keeping the blank obtained in step (3) at 440°C for 10 hours, perform precision die forging. During the pressing process, after the die forging is rapidly lowered to a distance of 100 mm from the parting surface, change the pressing rate to 0.5-3 mm / s and continue pressing until the set pressing amount is reached to ensure that the material fully fills the mold cavity. Other conditions are the same as in Example 1.

[0049] Example 10 This embodiment provides a high fatigue resistance and high strength and toughness aluminum alloy forging, and the design composition refers to Example 1.

[0050] The method for preparing high fatigue resistance and high strength and toughness aluminum alloy forgings provided in this embodiment refers to Example 1. The difference from Example 1 is that in step (5), the process parameters of the solution quenching treatment, cold pressing deformation treatment and multi-stage aging treatment are different. The specific steps are as follows: The forgings after step (4) were solution treated at a temperature of 465°C for 3 hours, then at 485°C for 1 hour, and then immediately water quenched. The quenching temperature was controlled at 60°C. After quenching, they were immediately cold pressed with a deformation of 4%. Within 48 hours after cold pressing, multi-stage aging treatment was carried out, first at 105°C for 6 hours, then at 145°C for 28 hours. After aging, the plates were air-cooled to room temperature. Other aspects were the same as in Example 1.

[0051] Comparative Example 1 This comparative example provides an aluminum alloy forging, whose designed composition, calculated by weight percentage, is: Zn: 6.5wt.%, Mg: 1.2wt.%, Cu: 1.4wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Sc: 0.02wt.%, Zr: 0.1wt.%, Si: 0.02 wt.%, Fe: 0.04 wt.%, the total impurity content is ≤0.1%, and the balance is Al.

[0052] The method for preparing the aluminum alloy forgings provided in this comparative example refers to Example 1.

[0053] Comparative Example 2 This comparative example provides an aluminum alloy forging, whose designed composition, calculated by weight percentage, is: Zn: 8.4wt.%, Mg: 1.7wt.%, Cu: 1.9wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Si: 0.02 wt.%, Fe: 0.04wt.%, and the total impurity content is ≤0.1%, with the balance being Al.

[0054] The method for preparing the aluminum alloy forgings provided in this comparative example refers to Example 1.

[0055] Comparative Example 3 This comparative example provides an aluminum alloy forging, whose designed composition, calculated by weight percentage, is: Zn: 8.4wt.%, Mg: 1.7wt.%, Cu: 1.9wt.%, Cr: 0.02 wt.%, Mn: 0.015 wt.%, Sc: 0.08wt.%, Zr: 0.04wt.%, Si: 0.02 wt.%, Fe: 0.04 wt.%, the total impurity content is ≤0.1%, and the balance is Al.

[0056] The method for preparing the aluminum alloy forgings provided in this comparative example refers to Example 1.

[0057] Performance Testing The aluminum alloy forgings prepared in Examples 1-10 and Comparative Examples 1-3 were subjected to performance tests. The tensile strength and elongation test standards were based on GB / T 16865-2013, the fracture toughness test standard was based on GB / T 4161-2007, and the fatigue limit test standard was based on HB 5287-1996. The results are shown in Table 1 below.

[0058] Table 1 As shown in Table 1, the tensile strength of the aluminum alloy forgings prepared by the present invention is between 556-631 MPa, which is 10-20% higher than that of 7050-T7451 with the same specifications. The elongation is between 11-15%, and the fracture toughness KIC is between 28-32 MPa•m 1 / 2 The smooth fatigue limit with a stress ratio of -1 exceeds 200 MPa, and the notch fatigue limit with Kt=1 exceeds 90 MPa, which meets the demand of future aviation equipment for high-comprehensive performance aluminum alloy materials.

[0059] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A high fatigue resistance and high strength and toughness aluminum alloy forging, characterized in that: The aluminum alloy forging comprises the following components by weight percentage: Zn: 7.0%-8.5%, Mg: 1.4%-2.3%, Cu: 1.6%-2.4%, Cr: 0.01%-0.04%, Mn: 0.01%-0.04%, Zr+Sc: 0.08%-0.15%, Si≤0.04%, Fe≤0.06%, and the balance is Al and unavoidable impurities, with a total impurity content of ≤0.1%; Among them, when the Sc content is greater than 0.05%, the Zr+Sc content is less than 0.09%; when the Sc content is less than 0.02%, the Zr+Sc content is greater than 0.14%; when the Sc content is 0.02%-0.05%, the Zr+Sc content is 0.09%-0.14%.

2. A method for preparing a high fatigue resistance and high toughness aluminum alloy forging according to claim 1, characterized in that: The steps include: S1. Using high-purity aluminum, industrial-purity zinc, high-purity magnesium, high-purity electrolytic copper, Al-Zr master alloy and Al-Sc master alloy as raw materials, after melting treatment, refining treatment and casting treatment, controlling the content of each element to achieve the requirements of the high fatigue resistance and high toughness aluminum alloy forgings to obtain an ingot; S2. The ingot is subjected to a multi-stage homogenization heat treatment, and the homogenized ingot is heated and forged to obtain a billet; S3. The billet is heated and then subjected to die forging, followed by solution quenching treatment, cold pressing deformation treatment and multi-stage aging treatment in sequence to obtain the high fatigue resistance and high strength and toughness aluminum alloy forging.

3. The method for preparing a high fatigue resistance and high toughness aluminum alloy forging according to claim 2, wherein: In step S1, the melting temperature is 720-760°C; and / or Refining temperature is 720-740°C; and / or The casting temperature is 730-750°C and the casting speed is 40-100 mm / min; and / or The ingot is a square ingot with a thickness of 320-460 mm or a round ingot with a diameter of 300-600 mm.

4. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2 or 3, characterized in that: In step S1, the melting and refining treatment is as follows: first, high-purity aluminum is added to a smelting furnace, completely melted at 720-760°C, and then the slag is removed. Then, industrial pure zinc, high-purity magnesium, high-purity electrolytic copper and Al-Zr master alloy are added. After all the alloy elements are melted, stirring and sampling are performed to adjust the composition; the aluminum alloy melt is introduced into an inert gas at 720-740°C for refining, the slag is removed after refining, and after the sample composition is tested and qualified, secondary refining is performed.

5. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2, wherein: In step S2, the multi-stage homogenization heat treatment is: first, keep warm at 420-450°C for 10-14 hours, then keep warm at 460-498°C for 18-24 hours, and finally keep warm at 450-470°C for 6-12 hours.

6. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2, wherein: In step S2, the forging process is as follows: heating the homogenized ingot to a temperature of 400-460°C for a holding time of 6-10 hours, and then performing 3-4 upsetting and 3-4 stretching deformation processes on the heated ingot, wherein the upsetting speed is ≤15 mm / s, the reduction amount during the stretching process is ≤70 mm, and the stretching distance is ≤30 mm.

7. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2, wherein: In step S3, during the die forging process, the heating temperature of the blank is 400-440°C, the insulation time of the blank is 4-10 hours, and the use temperature of the mold is ≥250°C.

8. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2, wherein: In step S3, the solution quenching treatment is: first, keeping at 440-465°C for 2-6 hours, then keeping at 470-485°C for 3-7 hours, and then immediately water quenching, the quenching temperature is 35-60°C, and the quenching transfer time does not exceed 25 seconds.

9. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2, wherein: In step S3, during the cold pressing deformation process, the deformation amount is 2%-6%.

10. The method for preparing a high fatigue resistance and high strength and toughness aluminum alloy forging according to claim 2, wherein: In step S3, the multi-stage aging treatment is: first, keeping the temperature at 100-120°C for 4-9 hours, and then keeping the temperature at 145-160°C for 11-28 hours.

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