Large-size SiC particle reinforced aluminum matrix composite cylindrical billet upsetting method

Abstract

The invention discloses an upsetting method for a large-size SiC particle reinforced aluminum matrix composite cylindrical billet, which is characterized in that an upsetting method combining integral pressing of a hydraulic machine and local pressing of a fast forging machine is adopted, and the difference of force action modes of two pressing modes on the peripheral surface and the end surface center part of the billet is combined, so that on one hand, the integral pressing amount is controlled, and on the other hand, the overall pressing amount is controlled; on the other hand, the hydraulic machine integrally presses down on the end face of the ingot blank to generate large compression deformation, pre-compression deformation is provided for subsequent local pressing down, and cracking of the center of the end face caused by local pressing down is avoided; according to the method, the problem that the large-size SiC particle reinforced aluminum matrix composite cylindrical billet is prone to cracking in the upsetting process is effectively solved, and the forming quality of billet upsetting is improved. The method is mainly used for upsetting forming of large-size SiC particle reinforced aluminum matrix composite cylindrical billets.

Description

Technical Field

[0001] The invention relates to a forging forming method, in particular to an upsetting forming method for a cylindrical billet of a large-size SiC particle reinforced aluminum-based composite material. Background Art

[0002] SiC particle reinforced aluminum matrix composites have introduced SiC ceramic particles with high strength and hardness into the aluminum matrix, and have excellent comprehensive properties such as high specific strength, high specific modulus, high wear resistance, better corrosion resistance, small thermal expansion coefficient, and good dimensional stability. They have been widely used in aviation, aerospace, nuclear energy and other fields. However, due to the introduction of reinforcing ceramic particles, the plasticity of the material is worse than that of the unreinforced matrix alloy, and it is extremely sensitive to tensile stress and is prone to cracking and failure under tensile stress.

[0003] During the application process, large-sized SiC particle reinforced aluminum-based composite cylindrical billets usually need to be forged and upset to obtain forged products that meet the specification requirements. However, due to the large size of the billet, the traditional overall upsetting method on the hydraulic press will produce bulges on the circumference of the billet, which is difficult to effectively eliminate. The circumference is subject to tensile stress and is prone to cracks, which may even cause the billet to be scrapped in severe cases. Therefore, it is necessary to provide an upsetting method to solve the cracking problem during the upsetting process of large-sized SiC particle reinforced aluminum-based composite cylindrical billets. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an upsetting method combining overall down-pressing of a hydraulic press and local down-pressing of a fast forging machine, which solves the problem of cracking during upsetting of large-size SiC particle reinforced aluminum-based composite cylindrical ingots.

[0005] In order to solve the above technical problems, the method for upsetting a cylindrical billet of a large-sized SiC particle reinforced aluminum-based composite material according to the present invention comprises the following steps:

[0006] Step 1: Preheat the upper and lower anvils of the hydraulic press to 250-350℃ in advance. Apply lubricant to the upper and lower end surfaces of the cylindrical billet in advance. After the billet is heated as required, place it vertically in the center of the lower anvil of the hydraulic press and press it down as a whole for upsetting. The pressing rate V≤5mm / s, the deformation ε1=(H0-H1) / H0×100%. Among them, ε1≤(0.5~0.7)ε max , ε max is the maximum uniform elongation determined by the tensile test of SiC particle reinforced aluminum matrix composite material, H0 is the height of the billet before this upsetting, and H1 is the height of the billet after this upsetting; after the billet is first upset on the hydraulic press, it is returned to the furnace while hot or cooled to room temperature as required to obtain billet 1;

[0007] Step 2: After the billet 1 in step 1 is heated as required, it is placed vertically on the lower anvil of the fast forging machine, and the upper anvil of the fast forging machine is pressed down to perform local upsetting; the lower anvil of the fast forging machine adopts a rotary worktable, and the upper anvil adopts a long flat anvil. The length of the upper anvil should be greater than 3d / 4, d is the diameter of the billet 1, and the width of the upper anvil can be flexibly selected according to the actual conditions such as the tonnage of the equipment and the diameter of the billet. It is recommended to select (1 / 24-1 / 12) d; the single-pass pressing amount of the upper anvil △H=(10%-15%)H1, after completing the previous pressing, the rotary worktable performs the next pressing, and the rotation angle θ of the worktable each time should be controlled between 12° and 18°, until the overall pressing is completed for one cycle, and the billet 2 is obtained;

[0008] Step 3: Turn the billet 2 in step 2 by 180°, place it on the workbench of the fast forging machine and continue to perform local upsetting, and press the upper anvil down in a single pass △H=(10%-15%)H1. After completing the previous pass, the workbench is rotated to perform the next pass. The rotation angle θ of the workbench should be controlled between 12° and 18° until the overall pressing is completed for one cycle to obtain the billet 3;

[0009] Step 4: Repeat steps 1, 2 and 3 in sequence until the billet is upset to the target height.

[0010] The large-size SiC particle reinforced aluminum-based composite material cylindrical ingot has a diameter of ≥500 mm and a height-to-diameter ratio of ≥0.5.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The invention discloses a method for upsetting a cylindrical billet of a large-size SiC particle reinforced aluminum-based composite material, which provides an upsetting method combining overall down-pressing of a hydraulic press and local down-pressing of a fast forging machine, and combines the difference in the force acting on the peripheral surface and the center of the end surface of the billet by the two down-pressing methods. On the one hand, the overall down-pressing amount is controlled within (0.5-0.7) ε max On the other hand, the hydraulic press as a whole presses down the end face of the ingot to produce a large compression deformation, which provides a pre-compression deformation for the subsequent local pressing method, and can avoid the cracking of the end face center caused by local pressing; in addition, the reheating during the process of the hydraulic press as a whole presses down + the fast forging machine local pressing can also eliminate the internal stress concentration generated by the previous deformation process to a certain extent. Therefore, the present invention can effectively solve the problem of easy cracking during the upsetting process of large-scale SiC particle reinforced aluminum-based composite cylindrical ingots, and improve the forming quality of the ingot upsetting. DETAILED DESCRIPTION

[0013] The present invention is further described in detail below through specific examples:

[0014] Example:

[0015] A bar with a size of φ730×950㎜ is required to produce a forging with a height of 180㎜. The forging steps are as follows:

[0016] Step 1: preheat the upper and lower anvils of the hydraulic press to 320°C in advance, apply lubricant to the upper and lower end surfaces of the billet in advance, and after the billet is heated as required, place it on the lower anvil of the hydraulic press and press it down as a whole for upsetting, with a pressing rate of V = 4.2 mm / s and a deformation of ε = 20%, to obtain billet a;

[0017] Step 2: After the billet a in step 1 is heated as required, it is partially upset on a fast forging machine, and the single pressing amount △L is about 70mm. After the previous pressing is completed, the rotating table is pressed for the next pressing. The rotation angle θ of the table should be controlled at about 15° until the overall pressing is completed for one circle to obtain the billet b;

[0018] Step 3: Turn the billet b in step 2 180° to continue local roughening, and the single pressing amount △L is about 70mm. After completing the previous pressing, the rotating worktable is used for the next pressing. The rotation angle θ of the worktable should be controlled at about 15° until the overall pressing is completed for one circle to obtain the billet c;

[0019] Step 4: Repeat steps 1, 2 and 3 in sequence until the billet is upset to a target height to obtain a forging 1.

[0020] Comparative Example:

[0021] Step 1: Heat the bar material with a size of φ730×950㎜;

[0022] Step 2: The ingot from step 1 is pressed down as a whole on the flat anvil of a hydraulic press to roughen it. After reaching the required roughening height of 180 mm, it is taken out and air-cooled to obtain a forging 2.

[0023] The surface of the forging 1 obtained in the embodiment is smooth and free of cracks, while the circumferential surface of the forging 2 in the comparative example is severely cracked. The method described in the present invention can effectively solve the problem of easy cracking during the upsetting process of large-size SiC particle reinforced aluminum-based composite cylindrical ingots, thereby improving the forming quality of the ingot upsetting.

Claims

1. A method for upsetting a cylindrical billet of a large-size SiC particle reinforced aluminum-based composite material, characterized in that: The steps include: Step 1: Preheat the upper and lower anvils of the hydraulic press to 250-350℃ in advance. Apply lubricant to the upper and lower end surfaces of the cylindrical billet in advance. After the billet is heated as required, place it vertically in the center of the lower anvil of the hydraulic press and press it down as a whole for upsetting. The pressing rate V≤5mm / s, the deformation ε1=(H0-H1) / H0×100%. Among them, ε1≤(0.5~0.7)ε max , ε max is the maximum uniform elongation determined by the tensile test of SiC particle reinforced aluminum matrix composite material, H0 is the height of the billet before this upsetting, and H1 is the height of the billet after this upsetting; after the billet is first upset on the hydraulic press, it is returned to the furnace while hot or cooled to room temperature as required to obtain billet 1; Step 2: After the billet 1 in step 1 is heated as required, it is placed vertically on the lower anvil of the fast forging machine, and the upper anvil of the fast forging machine is pressed down to perform local upsetting; the lower anvil of the fast forging machine adopts a rotary worktable, and the upper anvil adopts a long flat anvil. The length of the upper anvil should be greater than 3d / 4, d is the diameter of the billet 1, and the width of the upper anvil can be flexibly selected according to the actual conditions such as the tonnage of the equipment and the diameter of the billet. It is recommended to select (1 / 24-1 / 12) d; the single-pass pressing amount of the upper anvil △H=(10%-15%)H1, after completing the previous pressing, the rotary worktable performs the next pressing, and the rotation angle θ of the worktable each time should be controlled between 12° and 18°, until the overall pressing is completed for one cycle, and the billet 2 is obtained; Step 3: Turn the billet 2 in step 2 by 180°, place it on the workbench of the fast forging machine and continue to perform local upsetting, and press the upper anvil down in a single pass △H=(10%-15%)H1. After completing the previous pass, the workbench is rotated to perform the next pass. The rotation angle θ of the workbench should be controlled between 12° and 18° until the overall pressing is completed for one cycle to obtain the billet 3; Step 4: Repeat steps 1, 2 and 3 in sequence until the billet is upset to the target height.

2. The method for upsetting a large-sized SiC particle reinforced aluminum-based composite cylindrical ingot according to claim 1, characterized in that: The large-size SiC particle reinforced aluminum-based composite material cylindrical ingot has a diameter of ≥500 mm and a height-to-diameter ratio of ≥0.5.