Method for regulating and controlling anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multidirectional forging and heat treatment

Abstract

The invention provides a method for regulating and controlling anisotropy of 2195 aluminum lithium alloy by coupling low-temperature multidirectional forging and heat treatment, and relates to the field of regulation and control of anisotropy of aluminum lithium alloy. The invention aims to solve the technical problem that the 2195 aluminum-lithium alloy has obvious mechanical property anisotropy and limits the application range of the 2195 aluminum-lithium alloy in force-bearing components. The method comprises the following steps: 1, carrying out solution treatment on a 2195 aluminum-lithium alloy blank; secondly, the blank is preheated; 3, uniformly spraying a lubricant on the outer surface of the blank; fourthly, the blank is heated to the deformation temperature and then subjected to heat preservation; fifthly, the blank is placed on a hydraulic machine to be forged in multiple directions; sixthly, the blank is put into a muffle furnace to be subjected to solution treatment; and seventhly, the blank is put into an aging furnace to be subjected to aging treatment. The method can be used for the regulation and control process of the anisotropy of the 2195 aluminum-lithium alloy, and the anisotropy of the yield strength of the 2195 aluminum-lithium alloy part can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of anisotropy regulation of aluminum-lithium alloys, and particularly relates to a method for regulating anisotropy of 2195 aluminum-lithium alloys by coupling low-temperature multi-directional forging and heat treatment. BACKGROUND

[0002] With the development of the aerospace field towards high performance and long range, the spaceflight equipment has higher requirements for the lightweight and high strength of structural materials, and it is particularly important to introduce new high-strength lightweight materials and develop shape-integrated forming technology. Under this background, aluminum-lithium alloys become an ideal choice for replacing traditional aluminum alloys due to their excellent comprehensive performance. Researches show that the use of aluminum-lithium alloys instead of conventional aluminum alloys can achieve a 10%-15% weight reduction effect of structural parts, and the elastic modulus is increased by 6% and the stiffness is increased by 15%-20%.

[0003] Although aluminum-lithium alloys have significant lightweight advantages, the introduction of Li elements also leads to many disadvantages. Researches show that such alloys generally have low transverse toughness, fracture toughness and thermal instability. The most prominent one is the significant dependence of mechanical properties on direction, which directly limits the application range of the material in load-bearing components. In the extrusion process, there are two main sources of anisotropy of the material, one is that the grains produce preferred orientation, and strong texture leads to strong anisotropy of the alloy; the other is that the grain morphology changes significantly, and the typical fiber structure along the extrusion direction also causes strong anisotropy. SUMMARY

[0004] The application is to solve the problem that the anisotropy of 2195 aluminum-lithium alloys is significant, which directly limits the application range of the material in load-bearing components, and further proposes a method for regulating the anisotropy of 2195 aluminum-lithium alloys by coupling low-temperature multi-directional forging and heat treatment.

[0005] The technical scheme adopted by the application to solve the above problems is as follows: The application proposes a method for regulating the anisotropy of 2195 aluminum-lithium alloys by coupling low-temperature multi-directional forging and heat treatment, which comprises the following steps: Step one, solid solution treatment is performed on the 2195 aluminum-lithium alloy blank; Step two, the blank after the solid solution treatment is preheated; Step three, a lubricant is uniformly sprayed on the outer surface of the preheated blank; Step four, the blank after the lubricant spraying is heated to a deformation temperature and then is kept warm; Step five, the blank after the keeping warm is subjected to multi-directional forging on a hydraulic machine until a preset cumulative strain amount is reached; Step six, the blank after the forging is subjected to solid solution treatment again; Step seven, the blank after the re-solid solution treatment is aged.

[0006] Further, the solid solution treatment in step one and step six is carried out in a muffle furnace, and quenching treatment is used after the solid solution treatment.

[0007] Further, the solid solution treatment temperature in step one is 480-540 DEG C, and the solid solution treatment time is 0.5-2h.

[0008] Further, the preheating temperature in step two is 100-140 DEG C.

[0009] Further, the lubricant in step three is water-based graphite.

[0010] Further, the deformation temperature in step four is 140-260 DEG C.

[0011] Further, the nominal strain amount of the multi-directional forging in step five is 0.15-0.25.

[0012] Further, the nominal cumulative strain amount of the multi-directional forging in step five is not less than 0.45.

[0013] Further, the solid solution treatment temperature in step six is 480-540 DEG C, and the solid solution treatment time is 0.5-2h.

[0014] Further, the aging treatment temperature in step seven is 140-180 DEG C, and the aging treatment time is 36-60h.

[0015] The beneficial effects of the present application are: 1, the 2195 aluminum lithium alloy produced by the present application has fine equiaxed crystal and obvious weakened texture. Since the coupling of low-temperature multi-directional forging and heat treatment can promote the complete static recrystallization of the 2195 aluminum lithium alloy, the alloy structure can be refined, and the alloy texture can be effectively weakened.

[0016] 2, the anisotropy of the 2195 aluminum lithium alloy produced by the present application is significantly reduced. Since the bad material has experienced low-temperature multi-directional forging and subsequent solid solution and aging heat treatment, the blank has complete static recrystallization, the fiber structure with obvious preferred orientation is changed into weakly oriented equiaxed structure, so that the average Schmidt factor of the 2195 aluminum lithium alloy along 0°, 45° and 90° is close, and the anisotropy of the aluminum lithium caused by the preferred orientation of the grain is greatly reduced.

[0017] 3. The minimum yield strength of the 2195 aluminum-lithium alloy produced using this invention is significantly improved along the 0°, 45°, and 90° directions. The extruded alloy billet exhibits significant anisotropy, with the Schmidt factor being the largest and the yield strength the lowest along the 45° direction. After low-temperature deformation and heat treatment, due to the significant weakening of the alloy texture, the Schmidt factor along the 45° direction is significantly reduced, and the yield strength is significantly improved. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of multi-directional forging during the anisotropy control process of the 2195 aluminum-lithium alloy of the present invention; Figure 2 EBSD microstructure and inverse pole figure of extruded 2195 aluminum-lithium alloy, heat treatment of extruded 2195 aluminum-lithium alloy, and extruded alloy after 180℃ multi-directional forging and heat treatment. In the figure, (a) and (a1) are the original extruded alloy microstructure and inverse pole figure; (b) and (b1) are the microstructure of the extruded alloy after... Microstructure and inverse pole figure after heat treatment; (c) and (c1) are the microstructure and inverse pole figure of the extruded alloy after 180°C multi-directional forging and heat treatment by the method of the present invention; Figure 3 The tensile properties of 2195 aluminum-lithium alloy in three states (original extruded 2195 aluminum-lithium alloy, extruded 2195 aluminum-lithium alloy after heat treatment, and extruded alloy of the present invention after 180° multi-directional forging and heat treatment) are shown in the three directions of 0°, 45° and 90°. Detailed Implementation

[0019] This embodiment proposes a method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature deformation and heat treatment. The principle behind this is that aluminum-lithium alloys have high stacking fault energy, making them prone to dynamic recovery during medium- and high-temperature hot working, thus inhibiting dynamic recrystallization and making it difficult to refine the microstructure. Furthermore, under unidirectional loading such as upsetting or room-temperature deformation, the alloy's deformation capacity is poor, making it prone to cracking and unable to store enough dislocations. Therefore, it is difficult to induce static recrystallization during heat treatment. This invention innovatively improves the deformation capacity of 2195 aluminum-lithium alloy through multi-directional forging and utilizes low-temperature (140-260℃) deformation to suppress the softening behavior of 2195 aluminum-lithium alloy, such as dynamic recovery. This results in the storage of a large number of dislocations within the deformed microstructure, thus promoting static recrystallization during solution treatment. This not only refines the alloy microstructure but also effectively weakens the texture, significantly reducing alloy anisotropy and improving the performance of the extruded alloy along the 45° direction. Similar to the "barrel principle," the lowest strength often limits the overall performance of the alloy; the increase in yield strength along the 45° direction compensates for the alloy's performance "shortcomings." This is highly beneficial for the engineering application of 2195 aluminum-lithium alloy plastic forming components.

[0020] The method is performed according to the following steps: Step 1: Perform solution treatment on the 2195 aluminum-lithium alloy billet; The 2195 aluminum-lithium alloy billet was placed in a muffle furnace for solution treatment and then quenched. The solution treatment temperature is 480-540℃; The solution treatment time is 0.5-2 hours.

[0021] Step 2: Heat the 2195 aluminum-lithium alloy billet to the preheating temperature; The preheating temperature is 100-140℃.

[0022] Step 3: Apply lubricant evenly to the outer surface of the 2195 aluminum-lithium alloy billet; The lubricant is water-based graphite.

[0023] Step 4: Heat the 2195 aluminum-lithium alloy billet to the deformation temperature and then hold it at that temperature; The deformation temperature is 140-260℃.

[0024] Step 5: Place the 2195 aluminum-lithium alloy billet on a hydraulic press for multi-directional forging; The nominal strain per pass in the multi-directional forging process is 0.15-0.25; The nominal cumulative strain of the multi-directional forging is not less than 0.45.

[0025] Step Six: After forging, the 2195 aluminum-lithium alloy billet is placed in a muffle furnace for solution treatment; The solution treatment temperature is 480-540℃; The solution treatment time is 0.5-2 hours.

[0026] Step 7: Place the 2195 aluminum-lithium alloy billet into an aging furnace for aging treatment; The aging treatment temperature is 140-180℃; The processing time is 36-60 hours.

[0027] The beneficial effects of the present invention are verified using the following examples: Example: This embodiment describes a method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature deformation and heat treatment, which is carried out according to the following steps: Step 1: Place the 2195 aluminum-lithium alloy billet into a muffle furnace for solution treatment; The 2195 aluminum-lithium alloy billet is placed in a muffle furnace for solution treatment, and then quenched. The solution solution temperature of the 2195 aluminum-lithium alloy is 520℃; The solution treatment time for the 2195 aluminum-lithium alloy is 1 hour.

[0028] Step 2: Heat the 2195 aluminum-lithium alloy billet to the preheating temperature; The preheating temperature of the 2195 aluminum-lithium alloy is 120℃.

[0029] Step 3: Apply lubricant evenly to the outer surface of the 2195 aluminum-lithium alloy billet; The 2195 aluminum-lithium alloy lubricant is water-based graphite.

[0030] Step 4: Heat the 2195 aluminum-lithium alloy billet to the deformation temperature and then hold it at that temperature; The deformation temperature of the 2195 aluminum-lithium alloy billet is 180℃.

[0031] Step 5: Place the 2195 aluminum-lithium alloy billet on a hydraulic press for multi-directional forging; The nominal strain per pass of the multi-directional forging of the 2195 aluminum-lithium alloy billet is 0.2. The 2195 aluminum-lithium alloy billet undergoes three multi-directional forging passes, with a nominal cumulative strain of 0.6.

[0032] Step Six: After forging, the 2195 aluminum-lithium alloy billet is placed in a muffle furnace for solution treatment; The solution solution temperature of the 2195 aluminum-lithium alloy is 520℃; The solution treatment time for the 2195 aluminum-lithium alloy is 1 hour.

[0033] Step 7: Place the 2195 aluminum-lithium alloy billet into an aging furnace for aging treatment; The aging treatment temperature is 160℃; The processing time is 48 hours.

[0034] like Figure 2 , Figure 3 As shown, this embodiment has the following beneficial effects: I. The 2195 aluminum-lithium alloy produced using this embodiment exhibits a significantly refined microstructure and a markedly weakened texture. The original extruded alloy microstructure is fibrous, with a distinct preferred orientation and a texture type of [missing information]. <111> / / ED and <001> / / ED's bimodal texture, where <111> The ED electrode texture strength reaches 13.6 MRD. The texture type and strength remain almost unchanged after heat treatment. After multi-directional forging and heat treatment, the 2195 aluminum-lithium alloy exhibits equiaxed grains with a grain size of only about 20 μm, and the texture transforms... <112> / / ED texture, with a maximum texture intensity of only 1.7 MRD.

[0035] II. This example demonstrates a significant reduction in the anisotropy of 2195 aluminum-lithium alloy. The average Schmidt factors of the extruded 2195 aluminum-lithium alloy along the 0°, 45°, and 90° directions are 0.40, 0.47, and 0.44, respectively, while those of the low-temperature forged and heat-treated 2195 aluminum-lithium alloys along the same directions are 0.44, 0.45, and 0.45, respectively. Compared to the heat-treated extruded alloy, the yield strength anisotropy index (IPA) of the 180°C multi-directional forged and heat-treated alloy decreased from 15.7% to 1.6%.

[0036] Third, the yield strength of the 2195 aluminum-lithium alloy produced using this embodiment is significantly improved. Compared with the extruded 2195 aluminum-lithium alloy without low-temperature multi-directional forging, the yield strength of the 2195 aluminum-lithium alloy prepared using this embodiment method is increased from 396 MPa to 456 MPa in the 45° direction, an increase of 15%.

[0037] Comparative Example 1: This comparative example is implemented according to the following steps: Step 1: Place the 2195 aluminum-lithium alloy billet into a muffle furnace for solution treatment; The 2195 aluminum-lithium alloy billet is placed in a muffle furnace for solution treatment, and then quenched. The solution solution temperature of the 2195 aluminum-lithium alloy is 520℃; The solution treatment time for the 2195 aluminum-lithium alloy is 1 hour.

[0038] Step 2: Place the 2195 aluminum-lithium alloy billet into an aging furnace for aging treatment; The aging treatment temperature is 160℃; The processing time is 48 hours.

[0039] The results show that if the extruded 2915 aluminum-lithium alloy is not subjected to low-temperature multi-directional forging, but only solution treatment and aging, the anisotropy value (IPA) of the heat-treated alloy is 15.7%. Although the IPA value is lower than that of the extruded alloy, the anisotropy is still very significant compared with the alloy coupled with low-temperature forging (180℃) + heat treatment.

[0040] Comparative Example 2: This comparative example is implemented according to the following steps: Step 1: Place the 2195 aluminum-lithium alloy billet into a muffle furnace for solution treatment; The 2195 aluminum-lithium alloy billet is placed in a muffle furnace for solution treatment, and then quenched. The solution solution temperature of the 2195 aluminum-lithium alloy is 520℃; The solution treatment time for the 2195 aluminum-lithium alloy is 1 hour.

[0041] Step 2: Heat the 2195 aluminum-lithium alloy billet to the preheating temperature; The preheating temperature of the 2195 aluminum-lithium alloy is 120℃.

[0042] Step 3: Apply lubricant evenly to the outer surface of the 2195 aluminum-lithium alloy billet; The 2195 aluminum-lithium alloy lubricant is water-based graphite.

[0043] Step 4: Heat the 2195 aluminum-lithium alloy billet to the deformation temperature and then hold it at that temperature; The deformation temperature of the 2195 aluminum-lithium alloy billet is 460℃.

[0044] Step 5: Place the 2195 aluminum-lithium alloy billet on a hydraulic press for multi-directional forging; The nominal strain per pass of the multi-directional forging of the 2195 aluminum-lithium alloy billet is 0.2. The 2195 aluminum-lithium alloy billet undergoes three multi-directional forging passes, with a nominal cumulative strain of 0.6.

[0045] Step Six: After forging, the 2195 aluminum-lithium alloy billet is placed in a muffle furnace for solution treatment; The solution solution temperature of the 2195 aluminum-lithium alloy is 520℃; The solution treatment time for the 2195 aluminum-lithium alloy is 1 hour.

[0046] Step 7: Place the 2195 aluminum-lithium alloy billet into an aging furnace for aging treatment; The aging treatment temperature is 160℃; The processing time is 48 hours.

[0047] The results show that if the extruded 2915 aluminum-lithium alloy is forged at a higher multi-directional forging temperature, the material undergoes sufficient dynamic recovery during forging, thus suppressing recrystallization during heat treatment. Although the microstructure changes to some extent, it remains a fibrous structure. The anisotropy value (IPA) of the alloy after heat treatment is 9.2%. Although the IPA value is lower than that of the extruded alloy, the anisotropy is still very significant compared to the alloy coupled with low-temperature forging (180℃) + heat treatment.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment, characterized in that, The method includes the following steps: Step 1: Perform solution treatment on the 2195 aluminum-lithium alloy billet; Step 2: Preheat the solution-treated waste material; Step 3: Apply lubricant evenly to the outer surface of the preheated billet; Step 4: Heat the blank to its deformation temperature and then hold it at that temperature. Step 5: Perform multi-directional forging on the heat-insulated billet on a hydraulic press until the preset cumulative strain is reached; Step 6: Perform solution treatment on the forged billet again; Step 7: Aging treatment is performed on the billet after the second solution treatment.

2. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, Both the solution treatments described in steps one and six are carried out in a muffle furnace, followed by quenching.

3. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The solution treatment temperature in step one is 480-540℃, and the solution treatment time is 0.5-2h.

4. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The preheating temperature mentioned in step two is 100-140℃.

5. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The lubricant mentioned in step three is water-based graphite.

6. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The deformation temperature described in step four is 140-260℃.

7. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The nominal strain for a single pass of multi-directional forging described in step five is 0.15-0.

25.

8. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The nominal cumulative strain of the multi-directional forging described in step five shall not be less than 0.

45.

9. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The solution treatment temperature in step six is ​​480-540℃, and the solution treatment time is 0.5-2h.

10. The method for controlling the anisotropy of 2195 aluminum-lithium alloy by coupling low-temperature multi-directional forging and heat treatment according to claim 1, characterized in that, The aging treatment temperature described in step seven is 140-180℃, and the aging treatment time is 36-60h.

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