A forging method for improving cracking of high-temperature alloy end

Abstract

This invention provides a forging method to improve end cracking of high-temperature alloys, including (1) homogenization heat treatment; (2) slow pre-forging with an anvil: the H end of the high-temperature alloy is subjected to slow pre-forging with an anvil, and slow downward pressure is applied by upper and lower V-shaped anvils. The angle of the V-shaped anvil is 120-150°, the speed is less than 10mm / s, the deformation is controlled at 5%-10%, and after reaching the length, the anvil is stopped and constant pressure is maintained for 10-20s, then rotated 90°, and the above operation is repeated. After completing the pre-forging process, the A end of the high-temperature alloy is clamped and shaped. (3) Reheating in the furnace; (4) Upsetting and drawing. This invention performs slow pre-forging with an anvil at the end before forging, and then stops the anvil to compact the end. This improves the end stress distribution and compacts the end structure, enhances the end plasticity, and does not require additional forging cycles. It is highly operable, versatile, and easy to promote and apply, thereby improving the forging quality and yield of high-temperature alloys.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy forging technology, and more specifically to a forging method for improving end cracking in high-temperature alloys. Background Technology

[0002] High-temperature alloys are required to operate stably in high-temperature environments, complex stress conditions, and strong oxidizing and corrosive atmospheres. Therefore, high-temperature alloys must have excellent high-temperature mechanical properties, fatigue properties, fracture toughness, corrosion resistance, and other properties, and have broad application prospects in fields such as nuclear power, petrochemicals, aerospace, defense and military industries, and marine equipment.

[0003] The compositional differences among high-temperature alloys affect the ease of hot forming. High-temperature alloys exhibit varying degrees of difficulty in machining, surface cracking, and end-cracking tendency. For high-temperature alloy forging, temperature window control and forging process optimization can significantly improve forging efficiency, forming quality, and yield. However, effectively solving high-temperature alloy forging problems often requires a systematic consideration of compositional control, smelting quality, processing window, and deformation characteristics. End-cracking, as a forging problem affecting a class of high-temperature alloys, necessitates a forming method to first mitigate its cracking tendency, achieving high-quality, high-yield forging while preventing end-cracking. Reports on improving end-cracking in high-temperature alloys often involve attempts at compositional design, temperature window control, and forging deformation; however, these require specific research for different high-temperature alloys and lack general applicability. No method has been reported to improve end-cracking in a single class of high-temperature alloys. Summary of the Invention

[0004] To address the aforementioned technical problems, a forging method for improving end-point cracking in high-temperature alloys is provided. Before forging, this invention employs slow pre-forging with an end-point anvil to improve stress distribution at the end. Then, slow downward pressing compacts the end-point structure, improving its porosity. During subsequent heat treatment in the furnace, the diffusion of components that increase the tendency for end-point cracking is promoted, enhancing the end-point's plasticity and thus improving the tendency for end-point cracking under conventional upsetting and drawing processes.

[0005] The technical means employed in this invention are as follows:

[0006] A forging method for improving end cracking in high-temperature alloys specifically includes the following steps:

[0007] (1) Homogenization heat treatment: According to the as-cast microstructure characteristics of high-temperature alloys, corresponding homogenization heat treatment is carried out to ensure the elimination of low-melting-point eutectic products, harmful phases and uniform end structure.

[0008] (2) Slow pre-forging with anvil: After completing step (1), the H end of the high-temperature alloy is subjected to slow pre-forging with anvil. The upper and lower V-shaped anvils are used to press down slowly. The angle of the V-shaped anvil is 120-150°, the speed is less than 10mm / s, and the deformation is controlled at 5%-10%. After reaching the gauge, the anvil is stopped and the pressure is constant for 10-20s. The anvil is rotated 90° and the above operation is repeated. After completing the pre-forging process, the A end of the high-temperature alloy is clamped and shaped.

[0009] (3) Heat preservation in the furnace: After completing step (2), heat preservation is carried out for 2 to 8 hours above the melting temperature of the strengthening phase of the high-temperature alloy.

[0010] (4) Upsetting and drawing: After completing step (3), upsetting and drawing are carried out according to the forging ratio required by the high temperature alloy.

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

[0012] This invention develops a forging method to improve end-point cracking in high-temperature alloys. Before forging, a slow pre-forging process is performed on the end-point anvil during the initial forging stage, followed by a stop for compaction. This process improves the stress distribution at the end, strengthens the end-point microstructure, and enhances the end-point plasticity without requiring additional forging stages. The method utilizes a conventional upsetting and drawing process that meets technical requirements to achieve the forging of high-temperature alloy materials. Therefore, this invention is highly operable, versatile, and easy to promote and apply, improving the forging quality and yield of high-temperature alloys.

[0013] Based on the above reasons, this invention can be widely applied in fields such as high-temperature alloy forging. Detailed Implementation

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0015] This invention provides a forging method to improve end cracking in high-temperature alloys, specifically including the following steps:

[0016] (1) Homogenization heat treatment: According to the as-cast microstructure characteristics of high-temperature alloys, corresponding homogenization heat treatment is carried out to ensure the elimination of low-melting-point eutectic products, harmful phases and uniform end structure.

[0017] (2) Slow pre-forging with anvil: After completing step (1), the H end of the high-temperature alloy is subjected to slow pre-forging with anvil. The upper and lower V-shaped anvils are used to press down slowly. The angle of the V-shaped anvil is 120-150°, the speed is less than 10mm / s, and the deformation is controlled at 5%-10%. After reaching the gauge, the anvil is stopped and the pressure is constant for 10-20s. The anvil is rotated 90° and the above operation is repeated. After completing the pre-forging process, the A end of the high-temperature alloy is clamped and shaped.

[0018] (3) Heat preservation in the furnace: After completing step (2), heat preservation is carried out for 2 to 8 hours above the melting temperature of the strengthening phase of the high-temperature alloy.

[0019] (4) Upsetting and drawing: After completing step (3), upsetting and drawing are carried out according to the forging ratio required by the high temperature alloy.

[0020] Example 1

[0021] Implementation Case 1 uses a Φ508 ingot-shaped high-temperature alloy. The high-temperature alloy is smelted by VIM+ESR. The composition of the high-temperature alloy is Cr: 19.5-21%, W: 7.5-8.5%, Mo: 8-9%, (Al+Ti): 1-1.5%, Fe: 0.5-1%, Mn: 0.2-0.3%, Si: 0.2-0.5%, C≤0.05%, (B+Zr+Ce)≤0.15%, Ni: Bal.

[0022] The implementation steps are as follows:

[0023] (1) Homogenization heat treatment: Homogenization heat treatment at 1180-1200℃ is carried out according to the composition characteristics and microstructure of the high-temperature alloy for 15-20h.

[0024] (2) Slow pre-forging with an anvil: After completing step (1), the high-temperature alloy is slowly pressed down by the upper and lower V-shaped anvils. The V-shaped anvil angle is 120°, the pressing speed is 10-20 mm / s, the deformation is controlled at 5%-10%, and the anvil pressure is stopped for 10-20 seconds after reaching the gauge. The anvil is then rotated 90° and the above operation is repeated. After completing the pre-forging process, the high-temperature alloy is clamped and shaped at the A end.

[0025] (3) Reheating: After completing step (2), reheat the furnace at a temperature of 1130-1170℃ for 6-8 hours.

[0026] (4) Upsetting and drawing: After completing step (3), upsetting and drawing are carried out. The upsetting and drawing process is carried out 7 to 9 times, and the forging ratio is 8 to 15.

[0027] Example 2

[0028] Implementation Case 2 uses a Φ508 ingot-shaped high-temperature alloy smelted using VIM+VAR. The composition of the high-temperature alloy is: Cr: 19-22%, Mo: 7.5-9%, Fe: 6.5-8.5%, Nb: 2.5-4.5%, Ti: 1-2.5%, Al: 0.1-0.3%, Si≤0.1%, C≤0.05%, Ni: Bal. The implementation steps are as follows:

[0029] (1) Homogenization heat treatment: Based on the composition characteristics and as-cast microstructure of the high-temperature alloy, a two-stage homogenization treatment is carried out: homogenization at 1000~1100℃ for 5~10h and homogenization at 1150~1180℃ for 15~20h.

[0030] (2) Slow pre-forging with an anvil: After completing step (1), the high-temperature alloy is slowly pressed down by the upper and lower V-shaped anvils. The V-shaped anvil angle is 120°, the pressing speed is 10-20 mm / s, the deformation is controlled at 5%-10%, and the anvil pressure is stopped for 10-20 seconds after reaching the gauge. The anvil is then rotated 90° and the above operation is repeated. After completing the pre-forging process, the high-temperature alloy is clamped and shaped at the A end.

[0031] (3) Reheating: After completing step (2), reheat the furnace at a temperature of 1080-1130℃ for 3-5 hours.

[0032] (4) Upsetting and drawing: After completing step (3), upsetting and drawing are carried out. The upsetting and drawing process is carried out 8 to 10 times, and the forging ratio is 8 to 17.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A forging method for improving cracking of a high-temperature alloy end, comprising: (1) homogenization heat treatment: homogenization heat treatment is performed on the high-temperature alloy according to the as-cast structure characteristics of the high-temperature alloy, so as to ensure elimination of low-melting-point eutectic products and harmful phases of the high-temperature alloy and uniformity of the end structure of the high-temperature alloy; characterized in that it further comprises: (2) slow pre-forging of a die anvil: slow pre-forging of the H end of the high-temperature alloy is performed by pressing with an upper and lower V-shaped anvil, the V-shaped anvil angle is 120-150°, the pressing speed is less than 10 mm / s, the deformation amount of the H end of the high-temperature alloy is controlled to be 5-10% during each pressing, the anvil is stopped and kept constant pressure for 10-20 s after the size, the anvil is turned over by 90°, the above operation is repeated, and after the pre-forging process is completed, the A end of the high-temperature alloy is punched and shaped; (3) re-melting and heat preservation: heat preservation is performed above the strengthening phase resolubilization temperature of the high-temperature alloy, and the heat preservation time is 2-8 h; (4) upsetting and drawing to form a material: the high-temperature alloy is upset and drawn to form a material.