A method for forming a square thin plate forging blank of aluminum-based composite material

Abstract

The invention discloses a forming method of an aluminum-based composite material square thin plate forging billet, which mainly comprises: mold preheating, primary isothermal forging, intermediate billet machining, secondary isothermal forging, material separation, surface cleaning, and free forging of the square billet. The method can improve the deformation plasticity of the aluminum-based composite material, break through the limitation that the aluminum-based composite material cannot be free forged, and enable the aluminum-based composite material to replace the traditional aluminum alloy free forgings, give full play to the characteristics of the aluminum-based composite material such as high specific strength, wear resistance, fatigue resistance, and good dimensional stability, and solves the problem that the aluminum-based composite material thin plate square billet forgings in the prior art are difficult to directly process and the excellent characteristics of the material cannot be given full play.

Description

Technical Field

[0001] The present invention relates to the field of plastic forming of aluminum matrix composites, and particularly to a forming method for square forging blanks of aluminum matrix composite thin plates. Background Art

[0002] With the development of weapon equipment towards lightweight, high-performance and low-cost, the requirements for components are getting higher and higher, which promotes the development of material forming technology towards precision, high reliability and low cost. Compared with traditional aluminum alloy materials, aluminum matrix composites (2009 / SiC / 15p) have excellent comprehensive properties, such as high specific strength, wear resistance, fatigue resistance, good dimensional stability, etc., and can be widely used in lightweight components of advanced aircraft. Traditional square billet forgings of thin plates generally use the process of direct open-die forging of metal bar stock. However, due to the addition of particulate reinforcement phase (SiC), aluminum matrix composites are prone to cracking during the plastic deformation process and belong to difficult-to-deform materials. Therefore, in practical engineering applications, limited by materials and process methods, it is difficult to directly process square billet forgings of aluminum matrix composite thin plates, and the excellent properties of the materials cannot be exerted. Summary of the Invention

[0003] In view of this, the main object of the present invention is to provide a forming method for square thin plate forgings of aluminum matrix composites, which can solve the problems of easy cracking and difficult deformation during the plastic deformation process of aluminum matrix composites in the prior art.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A forming method for square thin plate forgings of aluminum matrix composites includes:

[0006] S1. Preheating the die. After installing an open die heating furnace and a flat die on a large die forging hydraulic press, preheat the die. The preheating time is ≥ 24 h, and the die temperature is ≥ 450 °C.

[0007] S2. First isothermal forging. Heat the aluminum matrix composite ingot wrapped with a jacket to 460 - 480 °C and hold for heat preservation. The heating and heat preservation coefficient for cold materials is 1.5 - 2 min / mm, and for hot materials is 1 - 1.5 min / mm. Then place it between the above flat dies for 1 - 3 passes of isothermal forging with a deformation amount of ≥ 50% to obtain blank A.

[0008] S3. Machining of the intermediate blank. First, use a lathe to remove the deformed jacket on blank A, leaving the deformed aluminum matrix composite ingot. Then machine the stress concentration area on the side of the cake blank and the connection between the deformed aluminum matrix composite ingot and the deformed jacket to obtain blank B.

[0009] S4. Secondary isothermal forging: First, preheat the die according to S1, then heat the blank after S3 processing to 460 - 480 °C and hold for heat preservation. The heat preservation coefficient for cold blanks is 1.5 - 2 min / mm, and for hot blanks is 1 - 1.5 min / mm. Then place it between the upper and lower flat dies for low-speed isothermal forging in 1 - 3 passes in the second stage, with the material deformation ≥ 20%. After the blank forging is completed, cool it in the air to obtain the aluminum matrix composite cake blank C;

[0010] S5. Material separation: Separate the aluminum matrix composite cake blank C obtained in S4 above to obtain blank D;

[0011] S6. Surface cleaning: After cleaning the graphite residue on the surface of the blank D using the wet shot peening machine equipment, grind and clean the surface defects;

[0012] S7. Free forging of square billets: Heat the blank D after surface cleaning to 460 - 480 °C and hold for heat preservation. The heat preservation coefficient for cold blanks is 1.5 - 2 min / mm, and for hot blanks is 1 - 1.5 min / mm. Then place it on the preheated hammer forging equipment for multi-pass low-speed free forging plastic processing. At the same time, during each pass of forging, the blank temperature should be monitored in real time ≥ 380 °C. After the blank forging is completed, cool it in the air.

[0013] Preferably, the jacket is a steel jacket with a thickness of 10 - 20 mm.

[0014] Preferably, the forging speed of the isothermal forging in S2 is 0.2 - 0.5 mm / s, and the speed decreases successively.

[0015] Preferably, during the isothermal forging in S2, the open die heating furnace remains powered on for heating.

[0016] Preferably, the forging speed of the low-speed isothermal forging in S4 is 0.1 - 0.2 mm / s, and the speed decreases successively.

[0017] Preferably, during the low-speed isothermal forging in S4, the heating furnace remains powered on for heating.

[0018] Preferably, a water cutting device or a sawing machine device is used for the material separation in S5.

[0019] Preferably, the forging hammer on the hammer forging equipment in S7 needs to be preheated with natural gas for not less than 4 h in advance.

[0020] Preferably, the pressing speed of the forging hammer in S7 is not greater than 5 mm / s, and the single pressing amount is not greater than 20 mm.

[0021] A method for forming a square thin plate forging blank of an aluminum matrix composite material according to the present invention has the following beneficial effects:

[0022] A forming method for a square thin plate forging blank of an aluminum matrix composite material disclosed by the present invention mainly includes: mold preheating, first isothermal forging, machining of the intermediate blank, second isothermal forging, material separation, surface cleaning, and free forging of a square blank, which can improve the deformation plasticity of the aluminum matrix composite material, break through the limitation that free forging cannot be implemented for the aluminum matrix composite material, enable the aluminum matrix composite material to replace the traditional aluminum alloy free forging parts, and give play to the characteristics of the aluminum matrix composite material such as high specific strength, wear resistance, fatigue resistance, and good dimensional stability, thereby improving the service life of related parts. On the other hand, the high cost of the aluminum matrix composite material enables the square blank of the aluminum matrix composite material processed by this method to greatly save the raw material cost, and its material utilization rate (more than 80%) is much higher than the method of machining a billet into a square blank after isothermal forging a cake, solving the problem that it is difficult to directly process the square blank forgings of the aluminum matrix composite material thin plate type in the prior art and the excellent properties of the material cannot be exerted. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 A three-dimensional schematic diagram of a square blank of a thin plate type according to an embodiment of the present disclosure;

[0025] Figure 2 A three-dimensional schematic diagram of an aluminum matrix composite material ingot wrapped with a cladding according to an embodiment of the present disclosure;

[0026] Figure 3 A schematic assembly diagram of a special isothermal forging heating furnace and a mold for an aluminum matrix composite material installed on a large die forging hydraulic press according to an embodiment of the present disclosure;

[0027] Figure 4 Blank A according to an embodiment of the present disclosure;

[0028] Figure 5 A schematic diagram of machining the intermediate blank according to an embodiment of the present disclosure;

[0029] Figure 6 A schematic diagram of the material separation method according to an embodiment of the present disclosure.

[0030]

SYMBOLS OF MAIN COMPONENTS

[0031] 1. Aluminum matrix composite material ingot;

[0032] 2. Cladding;

[0033] 3. Upper heat insulation plate;

[0034] 4. Upper flat die

[0035] 5. Upper heating furnace

[0036] 6. Lower heating furnace

[0037] 7. Lower flat die

[0038] 8. Lower heat insulation board

[0039] 9. Deformed aluminum matrix composite billet

[0040] 10. Deformed sheath Detailed implementation mode

[0041] The following further describes in detail a forming method for a square thin plate forging blank of an aluminum matrix composite material of the present invention in conjunction with the accompanying drawings and embodiments of the present invention.

[0042] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will describe the present invention in detail with reference to the accompanying drawings and embodiments.

[0043] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0044] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned accompanying drawings are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the implementation modes of this application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0045] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. can be used here to describe the spatial positional relationship of a device or feature shown in the figure with other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation described in the figure for the device. For example, if the device in the attached drawing is inverted, the device described as "above or over other devices or structures" will then be positioned "below or under other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0046] Refer to Figures 1 - 6 , the present invention provides a technical solution:

[0047] A forming method for a square thin plate forging blank of an aluminum matrix composite material, comprising:

[0048] S1. Die preheating: After installing the open die heating furnace and the flat die on the large die forging hydraulic press, preheat the die. The preheating time is ≥ 24 h and the die temperature is ≥ 450 °C;

[0049] As Figure 1 shown, the flat template includes: an upper flat die 4 and a lower flat die 7. The open die heating furnace includes: an upper heating furnace 5 and a lower heating furnace 6. The upper heating furnace 5 is located outside the upper flat die 4, the lower heating furnace 6 is located outside the lower flat die 7, the upper heat insulation plate 3 is located on the upper side of the upper heating furnace 5, and the lower heat insulation plate 8 is located on the lower side of the lower heating furnace 6. The total height of the flat die should be 20 - 50 mm greater than the sum of the heights of the upper heating furnace 5 and the lower heating furnace 6.

[0050] S2. First isothermal forging: Heat the aluminum matrix composite ingot 1 wrapped with the sleeve 2 to 460 - 480 °C and keep it warm. The heating and holding coefficient for cold materials is 1.5 - 2 min / mm, and for hot materials is 1 - 1.5 min / mm. Then place it between the above-mentioned flat dies for 1 - 3 passes of isothermal forging. The forging speed of the isothermal forging is 0.2 - 0.5 mm / s and the speed decreases successively. During the isothermal forging process, the open die heating furnace remains powered on for heating. The forging deformation amount is ≥ 50%, obtaining blank A. After the forging of blank A is completed, it is cooled in the air. The first isothermal forging improves the plasticity of the blank. The cross-sectional view of blank A after the first isothermal forging is as Figure 4 shown;

[0051] The jacket 2 is a steel jacket with a thickness of 10 - 20 mm. Due to the presence of the particulate reinforcement SiC, the plasticity of the original aluminum matrix composite ingot is extremely poor. After the aluminum matrix composite ingot 1 is processed by the process of wrapping the jacket 2, the ingot is kept under certain restraint and does not crack during the initial deformation stage, and then the performance indexes of the material are enhanced through plastic deformation.

[0052] S3. Machining of the intermediate billet: First, use a lathe to remove the deformed jacket 10 on the billet A, and the remaining deformed aluminum matrix composite ingot 9 is obtained. As Figure 5 shown, then machine the stress concentration area on the side of the cake billet. The stress concentration area on the side is area A in the appendix Figure 5 . Then machine the deformed aluminum matrix composite ingot 9 and the deformed jacket 10, as shown in area B in the appendix Figure 5 . The remaining machining dimensions are as shown in the appendix Figure 5 to obtain the billet B, avoiding cracking and pinching during the second-stage isothermal forging of the billet. Among them, area A is the stress concentration area, and area B is the large deformation area during the secondary isothermal forging.

[0053] S4. Secondary isothermal forging: First, preheat the flat die according to S1, then heat the billet B to 460 - 480 °C and keep it warm. The heating and holding coefficient for cold billets is 1.5 - 2 min / mm, and the heating and holding coefficient for hot billets is 1 - 1.5 min / mm. Then place it between the upper and lower flat dies for 1 - 3 passes of low-speed isothermal forging. The forging speed of the low-speed isothermal forging is 0.1 - 0.2 mm / s, and the speed decreases successively. During the low-speed isothermal forging process, the heating furnace remains powered on for heating, the material deformation is ≥ 20%, and after the billet forging is completed, it is cooled in the air to obtain the aluminum matrix composite cake billet C with plastic secondary strengthening;

[0054] S5. Dividing the material: Use a water jet cutting device or a sawing device to divide the aluminum matrix composite cake billet C to obtain the billet D. According to the size and shape of the required square thin plate, it can be divided into two, three, or four parts, as shown in Figure 6 (a), Figure 6 (b), Figure 6 (c) respectively.

[0055] S6. Surface cleaning: Use a wet shot blasting machine device to clean the graphite residue on the surface of the billet D, and then polish and clean the surface defects, such as microcracks, pinches, folds, and saw cut surfaces.

[0056] S7. Free forging square billet: Heat the billet D after surface cleaning to 460 - 480 °C and hold for heat preservation. The heat preservation coefficient for cold billets is 1.5 - 2 min / mm, and for hot billets is 1 - 1.5 min / mm. Then place it on the preheated hammer forging equipment for multi-pass low-speed free forging plastic processing. Depending on the size of the forging billet, generally 3 - 5 passes are required. The pressing speed of the forging hammer is not more than 5 mm / s, and the single pressing amount is not more than 20 mm. The forging hammer on the hammer forging equipment needs to be preheated with natural gas for not less than 4 h in advance, and the preheating temperature ≥ 200 °C. At the same time, the billet temperature should be monitored in real time during each pass of forging ≥ 380 °C. After the billet forging is completed, it is cooled in the air to obtain an aluminum matrix composite thin plate-like square billet forging with dimensions meeting the requirements.

[0057] The splitting methods in S5 are: splitting into two, splitting into three, and splitting into four. When the length and width of the final square thin plate are similar, the splitting method of dividing into four can be adopted; when the aspect ratio of the square thin plate is relatively large, the splitting method of dividing into three is adopted. In the method of splitting into three, except that the size of the 2# billet is regular, the billets after splitting are all in the shape of a sector. When implementing step seven, 1 - 2 additional passes of width sizing steps are required for shaping. When the aspect ratio of the square thin plate is between 1.5 - 2.5, the splitting method of dividing into two can be adopted.

[0058] Embodiment

[0059] To make the objectives, technical solutions, and advantages of the present invention clearer, the above forging method will be described below in conjunction with specific embodiments.

[0060] Taking the preparation of a certain aluminum matrix composite thin plate-like square billet forging as an example. Dimensions of the forging: 60 × 250 × 1230 mm, weight: 52 kg, material grade: 2009 / SiC / 15p.

[0061] First, select an aluminum matrix composite billet ingot 1 with a size specification of φ420 × 500 mm and wrap it with a jacket 2.

[0062] Then, on a large die forging hydraulic press, perform the first isothermal forging upsetting process on the aluminum matrix composite initial billet ingot in accordance with the method of S2 for 2 passes. The die is preheated in the manner of step one, with a preheating time of 24 h and a preheating temperature of 450. The height of the billet ingot is initially upset to 200 mm and cooled in the air after forging to obtain billet A. The specific heating and forging process parameters are shown in Table 1 below.

[0063] Table 1

[0064]

[0065] Next, process the obtained billet ingot with a thickness of 200 mm in accordance with the requirements of S3 to obtain billet B.

[0066] Then, on a large die forging hydraulic press, the initial ingot of the aluminum matrix composite material is subjected to a two-pass secondary isothermal forging upsetting process according to the method of S4. The die is preheated in the same way as in S1, with a preheating time of 24 h and a preheating temperature of 450 °C. The height of the ingot is finally upset to 120 mm and cooled in air after forging to obtain the aluminum matrix composite cake blank C. The specific heating and forging process parameters are shown in Table 2 below.

[0067] Table 2

[0068]

[0069]

[0070] Subsequently, the obtained aluminum matrix composite cake blank C is divided according to S5. As Figure 6 shown, the cake blank is divided into three on a water jet cutting device to obtain three blanks D, numbered 1#, 2#, and 3#. The width dimension of the 2# blank is 220 ± 5 mm, and the surfaces of the blanks D are cleaned and polished according to the method shown in step S6.

[0071] Finally, after the blanks D with clean and smooth surfaces are preheated for sufficient time, they are placed on a hammer forging device to perform 2 - 3 passes (3 passes for the middle blank and 2 passes for the two side blanks) of low-speed free forging to make the blank. A thin plate-like square blank with good surface quality and dimensions of 250 ± 5 × 60 ± 5 × 1230 ± 10 mm can be obtained and cooled in air after forging. The specific free forging process parameters are shown in Table 3 below.

[0072] Table 3

[0073]

[0074] After heat treatment of the aluminum matrix composite thin plate-like forging blank, its various mechanical properties are tested. The room temperature tensile property is ≥500 MPa, the elongation is ≥8%, and the high-cycle (number of cycles 10 7 ) stress fatigue limit is ≥200 MPa. The strength performance of the forging is greatly improved, and at the same time, a certain amount of deformation plasticity is retained.

[0075] The above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A method for forming a square thin plate forging blank of an aluminum-based composite material, characterized in that: include: S1. Preheat the mold. Install the open mold heating furnace and the flat mold on the large die forging hydraulic press to preheat the flat mold. The preheating time is ≥24h and the mold temperature is ≥450℃. S2, isothermal forging for the first time, heating the aluminum-based composite material billet wrapped with the sheath (2) to 460-480°C and then keeping it warm, with a cold material heating insulation coefficient of 1.5-2 min / mm and a hot material heating insulation coefficient of 1-1.5 min / mm, and then placing it between the above-mentioned flat molds for 1-3 passes of isothermal forging, with a deformation of ≥50%, to obtain billet A; S3, machining the intermediate billet, first using a lathe to remove the deformed sheath (10) on the billet A, leaving the deformed aluminum-based composite material billet, and then machining the stress concentration area on the side of the billet and the connection between the deformed aluminum-based composite material billet and the deformed sheath (10), to obtain billet B; S4, secondary isothermal forging, first preheat the flat die according to S1, then heat the blank B processed by S3 to 460-480℃ and keep it warm, the cold material heating insulation coefficient is 1.5-2min / mm, the hot material heating insulation coefficient is 1-1.5min / mm, then place it between the upper and lower flat die for 1-3 passes of low-speed isothermal forging, the material deformation is ≥20%, and the blank B is cooled in air after forging to obtain the aluminum-based composite material cake blank C; S5, dividing the aluminum-based composite material cake blank C to obtain blank D; S6. Surface cleaning: using a wet shot blasting machine to clean the graphite residue on the surface of the blank D, and then grinding and cleaning the surface defects; S7. Free forging square billet: heat the surface-cleaned billet D to 460-480℃ and then keep it warm. The heating and insulation coefficient of cold material is 1.5-2min / mm, and the heating and insulation coefficient of hot material is 1-1.5min / mm. Then place it on the preheated hammer forging equipment for multiple low-speed free forging plastic processing. At the same time, the billet temperature is monitored in real time during each forging pass to be ≥380℃. After forging, billet D is cooled in air.

2. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: The sheath is a steel sheath with a thickness of 10-20 mm.

3. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: The forging speed of the isothermal forging in S2 is 0.2-0.5 mm / s.

4. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: During the isothermal forging process in S2, the open die heating furnace is kept powered on for heating.

5. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: The forging speed of the S4 low-speed isothermal forging is 0.1-0.2 mm / s.

6. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: During the S4 low-speed isothermal forging process, the die heating furnace is kept powered on for heating.

7. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: The S5 material division uses water jet cutting equipment or sawing equipment.

8. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: The forging hammer on the hammer forging equipment in S7 is preheated in advance with natural gas for not less than 4 hours.

9. The method for forming a square thin plate forging billet of aluminum-based composite material according to claim 1, characterized in that: In the forging hammer in S7, the pressing speed is not greater than 5 mm / s, and the single pressing amount is not greater than 20 mm.

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