Forging method for improving cracking of high-strength titanium alloy forging with large height-diameter ratio

Abstract

The invention discloses a forging method for improving cracking of a high-strength titanium alloy forging with a large height-diameter ratio, which adopts a large-tonnage forging press to forge a high-strength titanium alloy forging stock with a large height-diameter ratio, and the forging comprises upsetting and drawing-out; the tonnage of the forging press is 1.4-1.8 times of the tonnage of TC4 titanium alloy forge piece forging equipment with the mass equal to that of the high-strength titanium alloy forging stock, and the width of a forging anvil of the forging press is 1.5-1.8 times of the equivalent diameter of the cross section of the high-strength titanium alloy forging stock. According to the forging method, the large-tonnage forging press is adopted to guarantee the forging deformation deepness of the high-strength titanium alloy with the large height-diameter ratio, overall compression and deformation of the cross section in the upsetting process are achieved in combination with the wide forging anvil, local upsetting caused by the too narrow anvil face of the forging anvil is avoided, and the forging quality of the titanium alloy is improved. The method is suitable for the technical field of titanium alloy forging.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy forging, and in particular relates to a forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio. Background Art

[0002] Lightweight and high strength have always been the goals pursued by aerospace materials. Reducing their own weight and increasing their strength are important ways to increase the payload of aircraft. Therefore, many aircraft structural parts use a large number of high-strength titanium alloys with a strength greater than 1000MPa. As new equipment develops towards large-scale and technological development, titanium alloy forgings are also developing towards large-scale and extra-large. For large-scale high-strength titanium alloy forgings, organizational uniformity has always been a huge problem. To ensure the organizational uniformity of large-scale forgings, sufficient forging deformation is the basis.

[0003] Usually, the height-to-diameter ratio of titanium alloy forgings suitable for forging is close to 2:1. When the height-to-diameter ratio exceeds 2.5:1, forming defects such as bending and twisting will occur during the upsetting process, and the axis of the forging blank will also be offset. High-strength titanium alloys have good processing plasticity and are not easy to crack during forging; but due to the large height-to-diameter ratio forgings exceeding 2.5:1, the deformation resistance is large. When the forging force is insufficient, an obvious double-drum shape will appear after upsetting. The middle layer metal of the double-drum shape does not produce plastic deformation or the plastic deformation is small, which will cause uneven organization, and large cracks are prone to occur on the side during the drawing process. At this time, forging must be stopped to remove the cracks, which will not only affect the overall deformation of the forging, but also increase metal loss. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio. The forging method adopts a large-tonnage forging press to ensure the deep penetration of the forging deformation of the high-strength titanium alloy with a large aspect ratio, and adopts a wider forging anvil to achieve the overall compression and deformation of the cross section during the upsetting process, thereby avoiding the high-strength titanium alloy being thin-waisted or interlayered due to the narrow forging anvil surface for local upsetting, and then causing cracks on the side during the drawing process, thereby solving the problem of easy cracking when forging high-strength titanium alloy with a large aspect ratio in the prior art.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a forging method for improving the cracking of high-strength titanium alloy forgings with a large aspect ratio, characterized in that a large-tonnage forging press is used to forge the high-strength titanium alloy forging blank with a large aspect ratio, and the forging includes roughening and drawing; the tonnage of the forging press is: 1.4 to 1.8 times the tonnage of the TC4 titanium alloy forging equipment with the same mass as the high-strength titanium alloy forging blank, and the forging anvil width of the forging press is: 1.5 to 1.8 times the equivalent diameter of the cross-section of the high-strength titanium alloy forging blank.

[0006] The present invention selects the tonnage of the high-strength titanium alloy forging press with a large aspect ratio according to the tonnage of the TC4 titanium alloy forging forging equipment with the same mass as the high-strength titanium alloy forging blank. This is because the TC4 titanium alloy is the most commonly used titanium alloy grade in this field and the forging theory of TC4 titanium alloy is the most abundant, which makes it easier for personnel in this field to select the tonnage of the high-strength titanium alloy forging press. The width of the forging anvil is set to 1.5 to 1.8 times the equivalent diameter of the cross section of the high-strength titanium alloy forging blank to ensure that the cross section of the high-strength titanium alloy forging blank undergoes overall deformation during the forging process.

[0007] The above-mentioned forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio is characterized in that the aspect ratio of the high-strength titanium alloy forging blank is greater than 2.5:1.

[0008] The above-mentioned forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio is characterized in that the upsetting method is: integrally deforming the cross section of the high-strength titanium alloy forging blank.

[0009] The above-mentioned forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio is characterized in that the deformation amount of a single upsetting pass is 50% to 60%.

[0010] The above-mentioned forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio is characterized in that the stretching method is: forging from the middle to both ends.

[0011] The above-mentioned forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio is characterized in that the deformation amount of a single stretching pass is 50% to 60%.

[0012] Since the plastic deformation of the high-strength titanium alloy with a large aspect ratio is small in the middle position after upsetting deformation, and the plastic conditions are inconsistent with those of other parts, the stretching process of forging from the middle to both ends is adopted, so that the non-deformation zones at both ends restrain the middle deformation zone, which can avoid the high-strength titanium alloy from cracking due to poor plastic conditions in the middle.

[0013] The above-mentioned forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio is characterized in that the forging process is: the process of upsetting followed by stretching is repeated no less than 4 times per fire, and tempering is performed between every 2 times.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The present invention adopts a large-tonnage forging press to ensure the deep penetration of the forging deformation of the high-strength titanium alloy, and adopts a wider forging anvil to achieve the overall compression and deformation of the cross section during the upsetting process, thereby avoiding the high-strength titanium alloy from being waist-shaped or having interlayers due to local upsetting due to the narrow forging anvil surface, thereby avoiding the side cracking during the forging process of the high-strength titanium alloy.

[0016] 2. The present invention adopts a drawing process of forging from the middle to both ends, and restrains the middle deformation zone by the non-deformation zones at both ends of the high-strength titanium alloy, thereby avoiding cracking of the high-strength titanium alloy due to poor plasticity conditions in the middle.

[0017] 3. The present invention improves the forging cracking phenomenon of high-strength titanium alloy with a large aspect ratio, enables the high-strength titanium alloy to undergo multiple upsetting and drawing deformations, and combines tempering and temperature compensation, thereby effectively increasing the overall deformation of the high-strength titanium alloy and improving the uniformity of the structure.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a surface morphology diagram of the forging obtained in Example 1 of the present invention.

[0020] Figure 2 This is a surface morphology diagram of the forging obtained in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0021] Example 1

[0022] The high-strength titanium alloy forging blank of this embodiment is a high-strength titanium alloy Ti-1300 with a cross-sectional equivalent diameter of 520 mm and a height of 1820 mm. The forging method is:

[0023] A forging press with a tonnage of 6300T and anvil width of 800mm is used to forge the high-strength titanium alloy forging billet. First, upsetting deformation is performed along the length direction. After upsetting to a height of 728mm, drawing deformation is performed. The first drawing hammer is pressed from the middle position of the high-strength titanium alloy forging billet, and then hammers are pressed continuously toward both ends. After drawing, the equivalent diameter of the cross section of the high-strength titanium alloy forging billet is 520mm; the upsetting deformation is repeated once and then tempered, and then the upsetting deformation is repeated twice to complete the forging process to obtain a forging.

[0024] The surface morphology of the forging obtained in this embodiment is as follows Figure 1 As shown, the surface quality of the forging is good and there is no obvious cracking.

[0025] Comparative Example 1

[0026] The difference between this comparative example and Example 1 is that a forging press with a tonnage of 3500T and an anvil width of 400mm is used to forge the high-strength titanium alloy forging blank. First, local upsetting deformation is carried out step by step along the length direction. After upsetting to a height of 1000mm, drawing deformation is carried out. The drawing is carried out by continuously pressing down with hammers from one end of the high-strength titanium alloy forging blank to the other end. After drawing, the equivalent diameter of the cross section is 1820mm. After two consecutive upsetting and drawing deformations, obvious cracks appear on the surface, and the forging must be stopped.

[0027] When the forging is stopped, the surface morphology of this comparative example is as follows Figure 2 As shown, obvious cracking occurred.

[0028] Example 2

[0029] The high-strength titanium alloy forging blank of this embodiment is a high-strength titanium alloy Ti-1300 with an equivalent cross-sectional diameter of 600 mm and a height of 2100 mm. The forging method is:

[0030] A forging press with a tonnage of 8000T and an anvil width of 900mm is used to forge the high-strength titanium alloy forging billet. First, upsetting deformation is performed along the length direction. After upsetting to a height of 840mm, drawing deformation is performed. The first drawing hammer is pressed from the middle position of the high-strength titanium alloy forging billet, and then hammers are pressed continuously toward both ends. After drawing, the equivalent diameter of the cross section of the high-strength titanium alloy forging billet is 600mm; then, the upsetting deformation is repeated once and then tempered, the upsetting deformation is repeated twice and then tempered, and finally an upsetting deformation is performed to complete the forging process to obtain a forging.

[0031] The forging obtained in this embodiment has good surface quality and no obvious cracks.

[0032] Example 3

[0033] The high-strength titanium alloy forging blank of this embodiment is a high-strength titanium alloy Ti-1500 with an equivalent cross-sectional diameter of 540 mm and a height of 1620 mm. The forging method is:

[0034] A forging press with a tonnage of 6300T and anvil width of 900mm is used to forge the high-strength titanium alloy forging billet. First, upsetting deformation is performed along the length direction. After upsetting to a height of 684mm, drawing deformation is performed. The first drawing hammer is pressed from the middle position of the high-strength titanium alloy forging billet, and then hammers are pressed continuously toward both ends. After drawing, the equivalent diameter of the cross section of the high-strength titanium alloy forging billet is 540mm. The upsetting and drawing deformation is repeated once and then tempered. Subsequently, the upsetting and drawing deformation is repeated twice to complete the forging process and obtain a forging.

[0035] The forging obtained in this embodiment has good surface quality and no obvious cracks.

[0036] Example 4

[0037] The high-strength titanium alloy forging blank of this embodiment is a high-strength titanium alloy Ti-1500 with a cross-sectional equivalent diameter of 500 mm and a height of 1300 mm. The forging method is:

[0038] A forging press with a tonnage of 6300T and anvil width of 900mm is used to forge the high-strength titanium alloy forging billet. First, upsetting deformation is performed along the length direction. After upsetting to a height of 650mm, drawing deformation is performed. The first drawing hammer is pressed from the middle position of the high-strength titanium alloy forging billet, and then hammers are pressed continuously toward both ends. After drawing, the equivalent diameter of the cross section of the high-strength titanium alloy forging billet is 500mm; the upsetting deformation is repeated once and then tempered, and then the upsetting deformation and tempering are repeated twice, and then the upsetting deformation is performed twice again to complete the forging process to obtain the forging.

[0039] The forging obtained in this embodiment has good surface quality and no obvious cracks.

[0040] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A forging method for improving cracking of high-strength titanium alloy forgings with a large aspect ratio, characterized in that: A large-tonnage forging press is used to forge a high-strength titanium alloy forging blank with a large aspect ratio, and the forging includes roughening and drawing. The tonnage of the forging press is 1.4 to 1.8 times the tonnage of a TC4 titanium alloy forging equipment with the same mass as the high-strength titanium alloy forging blank, and the width of the forging anvil of the forging press is 1.5 to 1.8 times the equivalent diameter of the cross section of the high-strength titanium alloy forging blank.

2. A forging method for improving cracking of high-strength titanium alloy forgings with large aspect ratio according to claim 1, characterized in that: The high-strength titanium alloy forging blank has a height-to-diameter ratio greater than 2.5:

1.

3. A forging method for improving cracking of high-strength titanium alloy forgings with large aspect ratio according to claim 1, characterized in that: The upsetting method is: integrally deforming the cross section of the high-strength titanium alloy forging blank.

4. A forging method for improving cracking of high-strength titanium alloy forgings with large aspect ratio according to claim 3, characterized in that: The deformation amount of a single upsetting pass is 50% to 60%.

5. A forging method for improving cracking of high-strength titanium alloy forgings with large aspect ratio according to claim 1, characterized in that: The stretching method is: forging from the middle to both ends.

6. A forging method for improving cracking of high-strength titanium alloy forgings with large aspect ratio according to claim 5, characterized in that: The deformation amount of a single stretching pass is 50% to 60%.

7. A forging method for improving cracking of high-strength titanium alloy forgings with large aspect ratio according to claim 1, characterized in that: The forging process is: the process of upsetting first and then stretching is repeated for no less than 4 times in each fire, and tempering and heating are performed between every 2 times.

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