A forging method for 7050 aluminum alloy forgings

Abstract

The present invention belongs to the field of aluminum alloy forging, and specifically relates to a forging method for 7050 aluminum alloy forgings. The method comprises: first firing: step 11, stretching the 7050 aluminum alloy ingot until the deformation in the length direction reaches 20%-50%, so as to obtain a forging blank; step 12, chamfering the forging blank; step 13, upsetting the forging blank after chamfering until the deformation in the length direction reaches 20%-50%; step 14, stretching the forging blank after upsetting to a first preset size; the deformation in the length direction of step 14 is also 20%-50%; second firing: step 21, chamfering the forging of the first preset size; step 22, upsetting the forging after chamfering until the deformation in the length direction reaches 20%-50%; step 23, stretching the forging after upsetting to a second preset size, and the deformation in the length direction of step 23 is also 20%-50%; third firing: repeating all steps of the second firing to obtain a reforged blank.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy forging, and in particular relates to a forging method for a 7050 aluminum alloy forging. Background Art

[0002] Aluminum alloys are widely used in aerospace, automotive and other fields due to their low density, high specific strength and specific stiffness. Al-Zn-Mg-Cu ultra-high strength aluminum alloys represented by 7050 aluminum alloy have excellent comprehensive properties and occupy an important position in the materials used in large aircraft manufacturing. They are often used to manufacture large load-bearing structural parts such as beams, trusses, and reinforcement frames.

[0003] At present, aluminum alloy aircraft structural parts are mainly formed by forging process. Due to the special working environment, in the design and manufacturing process of aircraft components, the main technical indicators are to enhance the strength and rigidity of the structural parts, and improve the stress corrosion resistance and fracture toughness of the structural parts. The performance of the material is mainly determined by the organization. At present, the main problem of raw materials is the organization problem. Therefore, it is of great significance to study the influence of forging process on the organization of forgings and control the material organization to improve the performance of 7050 aluminum alloy forgings. Summary of the invention

[0004] The purpose of the present invention is to provide a forging method for 7050 aluminum alloy forgings to avoid the instability of the forging structure, eliminate the residual cast structure, and thus improve the uniformity and stability of the product structure and performance.

[0005] The technical solution of the present invention:

[0006] A forging method for a 7050 aluminum alloy forging, comprising:

[0007] First firing: Step 11, stretching the 7050 aluminum alloy ingot until the deformation in the length direction reaches 20%-50% to obtain a forging blank; Step 12, chamfering the forging blank; Step 13, upsetting the chamfered forging blank until the deformation in the length direction reaches 20%-50%; Step 14, stretching the forging blank after upsetting to a first preset size; the deformation in the length direction of Step 14 is also 20%-50%;

[0008] Second firing: Step 21, chamfering the forging of the first preset size; Step 22, upsetting the chamfered forging until the deformation in the length direction reaches 20%-50%; Step 23, stretching the upset forging to the second preset size, and the deformation in the length direction of Step 23 is also 20%-50%;

[0009] The third fire: repeat all the steps of the second fire to obtain the reforged billet;

[0010] Among them, the heating temperature of the first fire is higher than the heating temperatures of the second and third fires; the heating temperature of the second fire is the same as the heating temperature of the third fire.

[0011] Furthermore, the entire forging furnace transfer process is required to be completed within 50 seconds; the heating temperature range for the first fire is (380-460)°C, and the heating temperature range for the second and third fires is (360-440)°C; the cold material heating and insulation time is calculated as 1.5-2.5min / mm; the hot material return to the furnace insulation time is calculated as 0.8-1.5min / mm.

[0012] Furthermore, the forging process of each fire is required to be completed within the range of 2.5-3 minutes. After the forging is completed, the final forging temperature is greater than or equal to 350°C.

[0013] Furthermore, during the entire forging process, the feed amount each time is ≤ 2 / 3 of the hammer anvil.

[0014] Furthermore, the amount of pressure per hammer is ≤50mm.

[0015] Furthermore, the pressing speed is 10 to 15 mm / s.

[0016] Furthermore, after obtaining the reforged billet, the method further comprises:

[0017] Forge the reforged billet on the forging machine to the drawing size.

[0018] Further, the reforged billet is forged on a forging machine to the drawing size, including:

[0019] The fourth fire: the forged billet is stretched, shaped, and the bulges at both ends are removed to prepare for deformation after solutionizing.

[0020] Furthermore, after the fourth forging, the final forging temperature is greater than or equal to 350°C.

[0021] Beneficial effects of the present invention:

[0022] The structure of the material is the key factor that determines the performance of the material. Only when the structure of the forging is qualified can the performance of the forging be qualified, and then the quality of the finished forging is guaranteed. By changing the first three fires of this technical solution, especially increasing the deformation temperature of the first fire, it can be ensured that the raw material structure of 7050 raw materials is basically uniform from ingot to forging before the forging is formed, and the residual cast structure in the material structure is basically removed. Then, through subsequent forming forging, the material structure is further optimized. While ensuring the drawing size requirements of the forging, the mechanical properties of the forging are also qualified, achieving a better match between strength and plasticity. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0024] Example:

[0025] 1. Forging

[0026] 1.1 The present invention uses a 2500t fast forging machine to forge the ingot.

[0027] 1.2 Material: 7050, forging blanking specifications:

[0028] 1.3 Heating:

[0029] 1.3.1 Heating temperature: 450℃ for the first fire, 420℃ for the second and third fires.

[0030] 1.3.2 Holding time: The heating and holding time of cold materials is calculated as 2.0min / mm; the holding time of hot materials returning to the furnace is calculated as 1.0min / mm.

[0031] 1.4 The forging production process is as follows:

[0032] 1.4.1 First Fire: Pull to length to mouth 270±5×~550, chamfer, upset to ~□355×320±10, pull to length to mouth 270±5×~550.

[0033] 1.4.2 Second fire: chamfer the mouth 270±5×~550, upset to ~□355×320±10, and stretch to mouth 270±5×~550.

[0034] 1.4.3 Third fire: Repeat the second fire once.

[0035] 1.5 Forging technical requirements are as follows:

[0036] ① Before forging, the anvil and the part of the fixture that contacts the blank should be fully preheated to 250±50℃;

[0037] ②Transfer time ≤ 60s (from opening of furnace door to forging)

[0038] ③ Final forging temperature ≥350℃.

[0039] 1.6 Cooling method: air cooling

[0040] 2 Forming forging:

[0041] 2.1 Heating:

[0042] 2.1.1 Heating temperature: 420℃.

[0043] 2.1.2 Holding time: The heating and holding time of cold materials is calculated at 2.0 min / mm; the holding time of hot materials returning to the furnace is calculated at 1.0 min / mm.

[0044] 2.2 Forging: 2500t fast forging machine (4201007) or 16MN free forging press (4201009) Forging size: □270±5×~500 Drawing and shaping to 170 +3 -0 ×270±3×≥780 (shaping, removing the bulges at both ends to prepare for deformation after solution treatment).

[0045] 3. Heat treatment (solution treatment): 471℃ for 4.5 hours and water cooling.

[0046] After solution treatment, cold forging must be carried out immediately within 2 hours, followed by aging treatment.

[0047] 4 Cold forging:

[0048] 4.1 Equipment: 2500t fast forging machine or 16MN open forging press.

[0049] 4.2 The forging size is required to be 170 +3 -0 ; Press according to the following dimensions; (pressing feed amount 200~260 each time) (173 pressed to 170~167; 172 pressed to 169~166; 171 pressed to 168~165; 170 pressed to 167~164).

[0050] 5. Heat treatment (aging): one-time aging at 121℃ for 6 hours and air cooling;

[0051] Secondary aging: 171℃ for 8 hours and air cooling.

[0052] 6 Physical and chemical test items:

[0053] Mechanical properties, fracture toughness, stress corrosion sensitivity factor, exfoliation corrosion resistance, stress corrosion resistance, macrostructure, fracture structure, microstructure.

[0054] 7Test Results:

[0055] After physical and chemical testing, all performance indicators of forgings meet the requirements of relevant standards. The specific values ​​are as follows:

[0056] 7.1 High and low magnification and fracture test results:

[0057] a) Low magnification and fracture: The structure is normal at low magnification and the structure is normal at fracture;

[0058] b) High magnification: No burning is observed and no residual cast structure is observed.

[0059] 7.2 Room temperature tensile and KIC tests.

[0060] The room temperature tensile properties and KIC test results of the forgings are shown in Table 1.

[0061] Table 1 Conventional tensile properties and KIC test of forgings

[0062]

[0063] 7.3 Stress corrosion: No stress corrosion cracking of the specimen Conclusion: Pass

[0064] 7.4 Exfoliation corrosion: EB level (standard requirement: not less than EB level) Conclusion: qualified

[0065] 7.5SCF=453-12×22.0=189<220 Conclusion: Pass 7.6Conductivity22.0MS / m Conclusion: Pass

[0066] 7.7 Flaw detection: Class A V109 probe Conclusion: Pass

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A forging method for a 7050 aluminum alloy forging, characterized in that: include: First firing: Step 11, stretching the 7050 aluminum alloy ingot until the deformation in the length direction reaches 20%-50% to obtain a forging blank; Step 12, chamfering the forging blank; Step 13, upsetting the chamfered forging blank until the deformation in the length direction reaches 20%-50%; Step 14, stretching the forging blank after upsetting to a first preset size; the deformation in the length direction of Step 14 is also 20%-50%; Second firing: Step 21, chamfering the forging of the first preset size; Step 22, upsetting the chamfered forging until the deformation in the length direction reaches 20%-50%; Step 23, stretching the upset forging to the second preset size, and the deformation in the length direction of Step 23 is also 20%-50%; The third fire: repeat all the steps of the second fire to obtain the reforged billet; The heating temperature of the first fire is higher than the heating temperatures of the second and third fires; the heating temperature of the second fire is the same as the heating temperature of the third fire; The entire forging furnace transfer process is required to be completed within 50 seconds; the heating temperature range for the first fire is 380-460℃, and the heating temperature range for the second and third fires is 360-440℃; the heating and insulation time for cold materials is calculated as 1.5-2.5min / mm; the insulation time for hot materials returning to the furnace is calculated as 0.8-1.5min / mm.

2. The method according to claim 1, characterized in that The forging process of each fire is required to be completed within 2.5-3 minutes. After forging, the final forging temperature is greater than or equal to 350℃.

3. The method according to claim 1, characterized in that: During the entire forging process, the feed amount each time is ≤2 / 3 of the hammer and anvil.

4. The method according to claim 3, characterized in that The amount of pressure per hammer is ≤50mm.

5. The method according to claim 4, characterized in that The pressing speed is 10~15mm / s.

6. The method according to any one of claims 1 to 5, characterized in that: After obtaining the reformed forged billet, the method further comprises: Forge the reforged billet on the forging machine to the drawing size.

7. The method according to claim 6, characterized in that Forge the reforged billet on the forging machine to the drawing size, including: The fourth fire: the forged billet is stretched, shaped, and the bulges at both ends are removed to prepare for deformation after solutionizing.

8. The method according to claim 7, characterized in that After the fourth forging, the final forging temperature is greater than or equal to 350°C.

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