A method of radial forging an aluminium matrix composite

Abstract

The application discloses a kind of aluminum matrix composite radial forging methods, belong to metal material processing field.The aluminum matrix composite blank is placed in heating furnace, with furnace temperature rises to 350~500 DEG C and is kept for 6~16 hours, blank is transferred to radial forging machine and is carried out radial forging, blank is turned over, and the blank is forged, immediately aluminum matrix composite blank is transferred to 350~500 DEG C heating furnace and is kept for 6~16 hours, repeat step S2 and S3, until blank is forged to the diameter size required.The application adopts the radial forging method of small deformation multiple deformation, realizes similar extrusion effect, the accurate control of blank diameter and the uniform distribution of deformation and microstructure in the radial direction of blank, effectively improves the uniformity of structure and product performance stability, and can realize high-quality, high productivity and low cost preparation of aluminum matrix composite rod for aluminum matrix composite.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing, and specifically relates to a radial forging method for aluminum-based composite materials. Background Technology

[0002] Aluminum-based composites are obtained by adding hard ceramic particles to aluminum alloys, combining the advantages of both aluminum alloys and ceramics. These composites possess excellent properties such as high specific strength, high specific stiffness, and corrosion resistance, making them promising for applications in automobiles, advanced aircraft, and other fields. However, the introduction of ceramic particles inhibits the plastic flow of the aluminum-based composite during deformation, increasing deformation resistance and making it prone to defects such as cracks and wrinkles during processing. Traditionally, extrusion is used to process aluminum-based composites, but the results are not ideal. The main problems include: 1) long extrusion time and low production efficiency; 2) the extrusion head is prone to cracking, and the tail has excess material that cannot be completely extruded, requiring the removal of both ends and wasting material; 3) the extruded product has a rough surface quality, requiring multiple subsequent surface finishing processes; 4) the billet deformation during extrusion is severely uneven, resulting in a highly uneven distribution of microstructure characteristics such as grain size, particle dispersion, and crystal orientation in the extruded aluminum-based composite, easily forming coarse grain rings at the extrusion section, affecting the uniformity and stability of the final product's performance and quality.

[0003] In summary, existing technologies in the processing of aluminum-based composite materials cannot achieve high production efficiency, high material utilization, and stable product performance. Therefore, this invention proposes a radial forging method for aluminum-based composite materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a radial forging method for aluminum-based composite materials, providing technical support for achieving high-quality and high-efficiency processing of aluminum-based composite material bars.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a radial forging method for aluminum-based composite materials, comprising the following steps:

[0007] S1: Place the aluminum-based composite billet in a heating furnace and hold it at 350–500℃ for 6–16 hours to fully heat and soften the billet, reduce its deformation resistance, and prevent cracking during forging, thus preparing it for forging. If the heating temperature is too low, the billet will have high hardness and weak deformation ability, making it prone to cracking during forging. If the heating temperature is too high, the eutectic phase in the billet will melt, resulting in defects. If the holding time is too short, the core of the billet will not be fully heated, and it will not deform evenly during forging. If the holding time is too long, it will result in a waste of energy and time.

[0008] S2: The fully heated and softened aluminum-based composite billet is transferred to a radial forging machine using mechanical clamps for radial forging. The billet is then turned around, and the unforged billet is forged again. The radial feed for the first forging pass is 3–8 mm. Excessive radial feed in the first forging pass will cause greater deformation on the surface of the billet than in the core, easily forming a fine-grained layer and leading to cracks in subsequent forging. Smaller deformation ensures uniform deformation of the billet, resulting in a uniform distribution of microstructure and properties across the bar cross-section.

[0009] This will help to obtain products with stable performance and controllable quality in the future;

[0010] S3: After the first forging is completed, the aluminum-based composite billet is immediately transferred to a preheated furnace at 350-500°C for heat preservation to restore defects and soften the billet. After forging, the temperature of some areas of the billet will drop, requiring reheating and heat preservation. In addition, after forging, a large number of dislocations and other defects are formed in the microstructure of the billet, which will reduce the deformation capacity of the billet. Heating and heat preservation are required to reduce the defect density and stress concentration, improve the deformation capacity, and prepare for subsequent forging.

[0011] S4: Repeat steps S2 and S3 to forge the billet to the required diameter, air cool, and end; the radial feed rate for each subsequent forging pass is increased by 5-10 mm compared to the first pass; the radial feed rate gradually increases with each pass, which saves forging time and forging passes compared to using a fixed radial feed rate, thus improving production efficiency; the holding time for each subsequent pass is increased by 2-8 hours compared to the first pass; as the number of forging passes increases, the cumulative deformation of the billet gradually increases, and the microstructure deformation becomes more severe, requiring an increased holding time to allow defects such as dislocations in the microstructure to recover, in order to obtain a billet with a uniformly distributed microstructure and properties; repeating steps S2 and S3 continuously reduces the billet diameter, eliminating the need for multiple dies and saving production costs; in the traditional extrusion method, the billet diameter is strictly limited by the die size, and each die can only process billets of one diameter, resulting in higher costs.

[0012] The radial forging method for aluminum-based composite materials described in this invention employs a radial forging method with small deformation amounts and multiple deformations. This method includes multiple heating and holding processes of the aluminum-based composite material billet, and multiple "radial forging-turning-radial forging" steps, to achieve an extrusion-like effect, i.e., the billet shrinks radially and elongates axially. By controlling deformation parameters such as forging temperature and hammer radial feed, precise control of the billet diameter and uniform distribution of deformation amount and microstructure in the radial direction of the billet are achieved. This avoids defects such as coarse grain rings, uneven performance, and head cracking that are prone to occur during extrusion, effectively improving the uniformity of microstructure and the stability of product performance.

[0013] Preferably, in step S2 and repeated step S2, the temperature of the billet is monitored at 2 to 6 points using an infrared thermometer during forging. The temperature measurement points are symmetrically distributed radially and evenly spaced axially. In traditional forging, a single point is used to monitor the billet temperature, which cannot accurately control temperature changes. Multi-point temperature monitoring can obtain more accurate billet temperature changes. During radial forging, the billet temperature rise is less than 30°C. Excessive temperature rise will cause the billet to overheat and produce void defects. The temperature drop should be less than 40°C. Excessive temperature drop will increase deformation resistance, reduce deformation capacity, and make it easy to crack.

[0014] Preferably, the axial feed speed of the billet during radial forging is 10-50 mm / s. Too high an axial feed speed will result in the billet not being forged completely, while too low an axial feed speed will prolong the forging time, increase the temperature drop of the billet, and make it prone to cracking. The billet rotation speed is 20-60 r / min. Too high or too low a rotation speed will cause the billet to be forged repeatedly, which is prone to folding.

[0015] Preferably, the time for transferring the billet from the heating furnace to the radial forging machine is less than 300 seconds, and the inner side of the transfer mechanical clamp is covered with refractory cotton padding to avoid scratching the surface of the billet during the clamping process.

[0016] Preferably, the heating furnace is a muffle furnace or an induction heating furnace, with a furnace temperature control accuracy of ±5°C within the range of 300–550°C.

[0017] Compared with existing technologies, this invention applies radial forging to aluminum-based composite materials, achieving high-quality, high-productivity, and low-cost preparation of aluminum-based composite material bars. The radial forging method provided by this invention requires only minor cutting at the head and tail of the processed bar, improving material utilization. In the extrusion method, the billet head is prone to bursting, while the tail cannot be fully extruded, resulting in significant material waste. Attached Figure Description

[0018] Figure 1 The image shows a scanning electron microscope (SEM) image of the microstructure of the radially forged aluminum matrix composite material in the embodiment. Detailed Implementation

[0019] This invention provides a radial forging method for aluminum-based composite materials, providing technical support for achieving high-quality and high-efficiency processing of aluminum-based composite material bars.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The following embodiments provide a method for radial forging of aluminum-based composite materials, including the following steps:

[0022] S1: Place the aluminum-based composite material blank in a heating furnace, with a heating rate of 5-15℃ / min, and heat it to 350-500℃ with the furnace, and hold it for 6-16 hours;

[0023] S2: Transfer the aluminum-based composite billet to a radial forging machine to perform radial forging of the billet, then turn the billet around and forge the unforged billet;

[0024] S3: After the first forging is completed, the aluminum-based composite material billet is immediately transferred to a heating furnace that has been preheated to 350-500°C and held for 6-16 hours.

[0025] S4: Repeat steps S2 and S3 until the billet is forged to the required diameter, air cool, and the process is complete.

[0026] Specifically, the radial feed rate for the first forging is 3-8 mm, and the radial feed rate for each subsequent forging is increased by 5-10 mm compared to the first forging, while the holding time is increased by 2-8 hours compared to the first forging.

[0027] Specifically, during the forging process, infrared thermometers are used to monitor the temperature of the billet at 2 to 6 points. The temperature measurement points are symmetrically distributed radially and evenly spaced axially. During radial forging, the billet temperature rise is less than 30°C and the temperature drop is less than 40°C.

[0028] Specifically, during radial forging, the axial feeding speed of the billet is 10–50 mm / s, and the billet rotation speed is 20–60 r / min.

[0029] Specifically, the time for the billet to be transferred from the heating furnace to the radial forging machine is less than 300 seconds, and the inside of the transfer mechanical clamp is covered with refractory cotton padding.

[0030] Specifically, the heating furnace is a muffle furnace or an induction heating furnace, with a furnace temperature control accuracy of ±5℃ within the range of 300 to 550℃.

[0031] Example 1

[0032] The aluminum-based composite billet is placed in a heating furnace at a heating rate of 10℃ / min, and heated to 400℃ with the furnace, and held at that temperature for 12 hours. Then, the aluminum-based composite billet is transferred to a radial forging machine with a transfer time of 180s. The inside of the transfer machine clamp is covered with refractory cotton padding. The radial feed is set to 3mm, and the billet is radially forged. Then, the billet is turned around, and the unforged billet is forged.

[0033] After the first forging is completed, the aluminum-based composite billet is immediately transferred to a heating furnace that has been preheated to 400°C and held at that temperature for 6 hours.

[0034] After the heat preservation is completed, the billet is transferred to the radial forging machine, the radial feed is set to 9mm, and a second forging is performed. Then the billet is turned around and the unforged billet is forged.

[0035] After the second forging is completed, the aluminum-based composite material billet is immediately transferred to a heating furnace that has been preheated to 400°C and held at that temperature for 10 hours.

[0036] After the heat preservation is completed, the billet is transferred to the radial forging machine, the radial feed is set to 16mm, and the third forging is carried out. Then the billet is turned around and the unforged billet is forged. After the forging is completed, it is air cooled and the process ends.

[0037] During the forging process, the axial feed speed is 20 mm / s, the billet rotation speed is 10 r / min, and the temperature of the billet is monitored at 4 points using an infrared thermometer. The temperature measuring points are symmetrically distributed radially and evenly spaced axially. During radial forging, the billet temperature rise is less than 30℃ and the temperature drop is less than 40℃. The heating furnace used in the forging process is a muffle furnace, and the furnace temperature control accuracy is ±5℃ within the range of 300~550℃.

[0038] Five samples were taken from the center to the edge of the forged aluminum matrix composite bar in this embodiment and tested. The samples were numbered A, B, C, D, and E in sequence. The axial performance data are shown in Table 1. The scanning electron microscope images of the microstructure of the aluminum matrix composite after radial forging are shown in the figure. Figure 1 As shown.

[0039] Table 1: Axial Room Temperature Mechanical Properties of Forged Bar Stock from Example 1

[0040] Sampling location Tensile strength / MPa Yield strength / MPa Elongation after fracture / % Elastic modulus / GPa A 590 520 11.1 76 B 597 529 10.5 76 C 595 523 10.7 77 D 596 525 11.3 78 E 592 527 11.0 77

[0041] Example 2

[0042] The aluminum-based composite billet is placed in a heating furnace at a heating rate of 8℃ / min, and heated to 350℃ with the furnace, and held at that temperature for 6 hours. Then, the aluminum-based composite billet is transferred to a radial forging machine with a transfer time of 240s. The inside of the transfer machine clamp is covered with refractory cotton padding. The radial feed is set to 8mm, and the billet is radially forged. Then, the billet is turned around, and the unforged billet is forged.

[0043] After the first forging is completed, the aluminum-based composite billet is immediately transferred to a heating furnace that has been preheated to 350°C and held at that temperature for 8 hours.

[0044] After the heat preservation is completed, the billet is transferred to the radial forging machine, the radial feed is set to 13mm, and a second forging is performed. Then the billet is turned around and the unforged billet is forged.

[0045] After the second forging is completed, the aluminum-based composite billet is immediately transferred to a heating furnace that has been preheated to 350°C and held at that temperature for 12 hours.

[0046] After the heat preservation is completed, the billet is transferred to the radial forging machine, the radial feed is set to 18mm, and the third forging is carried out. Then the billet is turned around and the unforged billet is forged. After the forging is completed, it is air cooled and the process ends.

[0047] During forging, the axial feed speed is 10 mm / s, and the billet rotation speed is 60 r / min. Infrared thermometers are used to monitor the temperature at two points on the billet, with the measuring points evenly spaced axially. During radial forging, the billet temperature rise is less than 30℃, and the temperature drop is less than 40℃. A muffle furnace is used in the forging process, with a furnace temperature control accuracy of ±5℃ within the range of 300–550℃.

[0048] Five samples were taken from the center to the edge of the aluminum-based composite material bar forged in this embodiment and tested. The samples were numbered A, B, C, D and E in sequence. Their axial performance data are shown in Table 2.

[0049] Table 2: Axial Room Temperature Mechanical Properties of Forged Bar Stock from Example 2

[0050] Sampling location Tensile strength / MPa Yield strength / MPa Elongation after fracture / % Elastic modulus / GPa A 610 540 11.0 77 B 608 539 10.5 76 C 605 543 10.0 78 D 615 545 11.3 78 E 612 537 11.2 77

[0051] Example 3

[0052] The aluminum-based composite billet is placed in a heating furnace at a heating rate of 15℃ / min, and heated to 500℃ with the furnace, and held at that temperature for 16 hours. Then, the aluminum-based composite billet is transferred to a radial forging machine with a transfer time of less than 300s. The inside of the transfer machine clamp is covered with refractory cotton padding. The radial feed is set to 6mm, and the billet is radially forged. Then, the billet is turned around, and the unforged billet is forged.

[0053] After the first forging is completed, the aluminum-based composite billet is immediately transferred to a heating furnace that has been preheated to 500°C and held at that temperature for 16 hours.

[0054] After the heat preservation is completed, the billet is transferred to the radial forging machine, the radial feed is set to 16mm, and a second forging is performed. Then the billet is turned around and the unforged billet is forged.

[0055] After the second forging is completed, the aluminum-based composite billet is immediately transferred to a heating furnace that has been preheated to 500°C and held at that temperature for 24 hours.

[0056] After the heat preservation is completed, the billet is transferred to the radial forging machine, the radial feed is set to 26mm, and the third forging is carried out. Then the billet is turned around and the unforged billet is forged. After the forging is completed, it is air cooled and the process ends.

[0057] During forging, the axial feed speed is 50 mm / s, and the billet rotation speed is 40 r / min. Infrared thermometers are used to monitor the temperature at six points on the billet. These points are symmetrically distributed radially and evenly spaced axially. During radial forging, the billet temperature rise is less than 30℃, and the temperature drop is less than 40℃. An induction heating furnace is used for forging, with a temperature control accuracy of ±5℃ within the range of 300–550℃.

[0058] Five samples were taken from the center to the edge of the aluminum-based composite material bar forged in this embodiment and tested. The samples were numbered A, B, C, D and E in sequence. Their axial performance data are shown in Table 3.

[0059] Table 3: Axial Room Temperature Mechanical Properties of Forged Bar Stock from Example 3

[0060] Sampling location Tensile strength / MPa Yield strength / MPa Elongation after fracture / % Elastic modulus / GPa A 635 553 9.4 79 B 631 559 9.3 78 C 637 555 9.0 77 D 634 550 10.0 78 E 632 552 9.5 77

[0061] The above description of the embodiments is intended to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the principles of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method of radial forging an aluminum matrix composite material, characterized by, The method comprises the following steps: S1: the aluminum matrix composite blank is placed in a heating furnace, the heating rate is 5-15 ℃ / min, the furnace is heated to 350-500 ℃, and the temperature is kept for 6-16 hours; S2: the aluminum matrix composite blank is transferred to a radial forging machine, the blank is radially forged, then the blank is turned over, and the un-forged blank is forged, i.e. first-time forging; S3: after the first-time forging is completed, the aluminum matrix composite blank is immediately transferred to a heating furnace at 350-500 ℃, and the temperature is kept for 6-16 hours; S4: steps S2 and S3 are repeated until the blank is forged to the required diameter size, air-cooled, and finished; The radial feeding amount of the first-time forging is 3-8 mm, and the radial feeding amount of each subsequent time forging is increased by 5-10 mm than that of the first-time forging, and the holding time is increased by 2-8 hours than that of the first-time forging; During the radial forging, the temperature of 2-6 points of the blank is monitored by an infrared temperature detector, the temperature measuring points are symmetrically distributed in the radial direction and equally spaced in the axial direction, the temperature rising range of the blank during the radial forging is less than 30 ℃, and the temperature falling range is less than 40 ℃; During the radial forging, the axial feeding speed of the blank is 10-50 mm / s, and the rotation speed of the blank is 20-60 r / min.

2. The aluminum matrix composite radial forging method of claim 1 wherein, The time for transferring the blank from the heating furnace to the radial forging machine is less than 300 s, and the inside of the transfer mechanical clamp is covered with a soft pad of refractory cotton.

3. The aluminum matrix composite radial forging method of claim 1 wherein, The heating furnace is a muffle furnace or an induction heating furnace, the furnace temperature control precision is ±5 ℃ in the range of 300-550 ℃.

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