Preparation method of high-uniformity TA15 titanium alloy thick forging blank

Abstract

This invention relates to the field of titanium and titanium alloy processing technology, specifically disclosing a method for preparing a high-uniformity TA15 titanium alloy thick forging billet. The method involves forging in the initial stage, single-phase zone forging, two-phase zone upsetting and drawing, billet preparation, rolling, and straightening using a quick-break mill. Billet preparation involves heating the billet at 30-70°C below the β phase transformation point and then drawing it in 1-2 passes, controlling the total deformation to 50%-80%, followed by air cooling. Rolling involves dividing the billet obtained from the drawing and preparing into single-length portions based on the billet length, heating it at 30-60°C below the β phase transformation point, and then performing a single-pass transverse rolling process in 4-7 passes. The deformation per pass is 10%-25%, and the total deformation is 50%-80%. This single-pass transverse rolling effectively reduces the tonnage requirements of the rolling mill and can obtain a finished forging billet with a high-magnification uniform structure and a low-magnification indistinct structure.

Description

Technical Field

[0001] This invention relates to the field of titanium and titanium alloy processing technology, specifically to a method for preparing a high-uniformity TA15 titanium alloy thick (thickness 60-150mm) forging billet. Background Technology

[0002] TA15 titanium alloy is a medium-strength titanium alloy with good comprehensive mechanical and processing properties. It has higher strength and weldability than TC4 titanium alloy and is mainly used to manufacture structural parts and welded load-bearing components that operate at temperatures below 500°C for extended periods. Applications include various engine blades and casings, and various sheet metal parts, beams, joints, large panels, and welded load-bearing frames for aircraft. For TA15 titanium alloy forgings thicker than 60mm, conventional fast forging or double rolling methods are generally used. Forgings obtained by conventional fast forging are prone to uneven low-magnification striations, while double rolling processes require more advanced equipment to produce large-sized billets. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing high-uniformity TA15 titanium alloy thick (thickness 60-150mm) forging blanks. This method can prepare large-size thick forging blanks with low-magnification uniform blurring and high-magnification uniform microstructure in all directions.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a high-uniformity TA15 titanium alloy thick forging billet is achieved through forging, single-phase forging, two-phase upsetting and drawing forging, billet preparation, rolling, and straightening with a quick-break machine. The method is characterized by the following steps: the billet preparation involves heating at 30-70°C below the β phase transformation point and then drawing it in 1-2 passes, controlling the total deformation to be 50%-80%, followed by air cooling. The rolling process involves dividing the billet obtained from the drawing and drawing process into single-length portions based on the billet length, heating it at 30-60°C below the β phase transformation point, and then performing a single-pass transverse rolling process, completed in 4-7 passes, with a single-pass deformation of 10%-25% and a total deformation of 50%-80%.

[0005] Furthermore, the above-mentioned method for preparing a high-uniformity TA15 titanium alloy thick forging billet is specifically achieved through the following steps: Step 1) Forging: Heat the resistance furnace to 750-850℃, place the furnace, hold for 2-3 hours, raise the temperature to 1100-1200℃, hold for 120-240 minutes, then remove from the furnace and forge on a high-speed forging machine. The upsetting deformation is 30-60%, and the forging is followed by air cooling. Step 2) Single-phase region upsetting and drawing forging: After heating at 30-100℃ above the β phase transformation point, forge 2-3 times, with an upsetting deformation of 30-60%, and air cool after forging; Step 3) Two-phase region upsetting and forging: After heating at 30-70℃ below the β phase transformation point, forge 2-5 times, with an upsetting deformation of 40-60%, and air cool after forging; Step 4) Drawing and billet preparation: After heating at 30-70℃ below the β phase transformation point, the billet is drawn 1-2 times. The drawing feed is ≤250mm, the pressing rate is ≥30mm / s, and the total deformation is 50-80%. After forging, the billet is air-cooled and pre-machined to a bright surface, resulting in a billet with a thickness of 2-2.5 times that of the finished forging billet and a width of 0.5-0.6 times that of the finished forging billet. Step 5) Transverse rolling: The billet obtained in step 4) is divided into single-length portions according to the billet length. Then, it is transversely rolled in one pass at 30-60℃ below the β phase transformation point, which is completed in 4-7 passes. The deformation amount in a single pass is 10-25%, and the total deformation amount is 50-80%. Step 6) Straightening and machining: Heat the rolled forging billet to 750-850℃, straighten it using a high-speed forging machine, air cool it after forging, and then machine it according to the product dimensions.

[0006] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention accumulates sufficient longitudinal deformation during the elongation stage of rapid forging, and then prepares the finished forging billet through a single transverse rolling process, effectively replacing the existing multi-reversal rolling process. Existing technologies employ two reversal rolling processes. To ensure sufficient deformation in each process, the thickness of the initial billet needs to be increased by more than 40% compared to a single rolling process. However, this places relatively high tonnage requirements on equipment such as hot rolling mills, and the rolling process cost is also relatively high. For example, for a 100mm thick slab, the initial slab thickness using two reversal rolling processes needs to reach over 350mm, while a single rolling process can control the slab thickness to below 200mm. Therefore, the single transverse rolling process of this invention effectively reduces the tonnage requirements for rolling. 2. In the billet drawing and billet preparation stage, a small feed rate + rapid forging method is adopted to achieve rapid drawing of the billet and obtain a better longitudinal forging streamline, so as to prepare for reducing the streamline effect of cross rolling. 3. This invention utilizes a specific two-phase elongation method on a conventional fast forging process to accumulate a certain amount of longitudinal deformation during the billet elongation stage. Then, based on the finished forging billet size, the billet size is calculated, and the forging billet is rolled through a single transverse rolling process. This replaces the existing transverse rolling + longitudinal rolling process for preparing slabs with the longitudinal drawing + transverse rolling process of this invention, achieving the goal of obtaining similar uniform microstructure in all directions. It can obtain finished forging billets with uniform microstructure at high magnification and blurred microstructure at low magnification. Attached Figure Description

[0007] Figure 1This is a 200x high-magnification microstructure image of the forging billet prepared in Example 1 of the present invention; Figure 2 This is a low-magnification microstructure image of the forging billet prepared in Embodiment 1 of the present invention. Figure 3 This is a 200x high-magnification microstructure image of the forging billet prepared in Example 2 of the present invention; Figure 4 This is a low-magnification microstructure diagram of the forging billet prepared in Example 2 of the present invention.

[0008] Figure 5 This is a low-magnification microstructure image of a TA15 slab prepared using a conventional high-speed forging mill. Implementation

[0009] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. The following are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any identical or similar solutions without departing from the concept of the present invention should fall within the scope of protection of the present invention. Furthermore, in the following text, "□" refers to the side length of the square blank. Example 1

[0010] In this embodiment, the material processed is a TA15 titanium alloy ingot with a diameter of Φ780mm, and a 100×1000×2000mm forging blank is prepared according to the method of the present invention.

[0011] Step 1) Billet forging: Heat the resistance furnace to 800℃, load the furnace, hold for 2 hours, raise the temperature to 1150℃, hold for 240 minutes, and then remove the billet from the furnace and perform billet forging on a high-speed forging machine. The upsetting deformation is 50%. After forging, air cool. The forged size is □650×1400mm. Step 2) Single-phase region upsetting and drawing forging: After heating at 100℃ and 40℃ above the β phase transformation point respectively, it is forged twice, with a total upsetting deformation of 50%. After forging, it is air-cooled, and the forged size is □650×1400mm. Step 3) Two-phase region upsetting and drawing forging: After heating at 40℃, 40℃ and 50℃ below the β phase transformation point, it is forged 3 times, with a total upsetting deformation of 45%. After forging, it is air-cooled and the forged size is □650×1400mm. Step 4) Drawing and billet preparation: After heating at 50°C below the β phase transformation point, perform one drawing operation with a deformation of 50-80%. After forging, air cool. The forged dimensions are 230 (thickness) × 1130 (width) × 2250 (length) mm. The machined dimensions are 220 (thickness) × 1100 (width) × 2250 (length) mm. Cut to a length of 1050 mm along the length direction. The sawed dimensions are 220 (thickness) × 1050 (width, original length direction) × 1100 (length, original width direction) mm. Step 5) Transverse rolling: The elongated billet obtained in step (4) is divided into two billets according to the blank length calculated by the forging billet length. After heating at 30-60℃ below the β phase transformation point, it is rolled in one pass in 5 passes. The deformation amount per pass is 10-25%. The rolled size is 110 (thickness) × 1050 (width) × 2200 (length) mm.

[0012] Step 6) Quick forging straightening and machining: Heat the rolled forging billet to 750-850℃, straighten it using a quick forging machine, air cool it after forging, and the machined size is 100×1000×2000mm.

[0013] The microstructure of the forged billet from Example 1 was examined, and the results are as follows: Figure 1 , Figure 2 It can be seen that the high-magnification structure in both the horizontal and vertical directions is uniform and well-broken, while the low-magnification structure is blurry. Example 2

[0014] In this embodiment, the material being processed is a TA15 titanium alloy ingot with a diameter of Φ780mm, and a 70×1400×2500mm forging blank is prepared according to the method of the present invention.

[0015] Step 1) Forging: Heat the resistance furnace to 800℃, place the furnace, hold for 2 hours, raise the temperature to 1150℃, hold for 240 minutes, and then take it out of the furnace for forging on a high-speed forging machine. The upsetting deformation is 50%. After forging, air cool. The forged size is □750×1600mm. Step 2) Single-phase region upsetting and drawing forging: After heating at 100℃ and 40℃ above the β phase transformation point respectively, it is forged twice, with a total upsetting deformation of 50%. After forging, it is air-cooled, and the forged size is □750×1600mm. Step 3) Two-phase region upsetting and drawing forging: After heating at 40℃, 40℃ and 50℃ below the β phase transformation point, it is forged 3 times, with a total upsetting deformation of 45%. After forging, it is air-cooled and the forged size is 380×1200×2000mm. Step 4) Drawing and billet preparation: After heating at 50°C below the β phase transformation point, the billet is drawn twice, with a total deformation of 50-80%. After forging, it is air-cooled. The forged dimensions are 230 (thickness) × 1300 (width) × 3050 (length) mm. The machined dimensions are 220 (thickness) × 1300 (width) × 2900 (length) mm. The billet is cut to a length of 1450 mm along the length direction. The sawed dimensions are 170 (thickness) × 1450 (width, original length direction) × 1300 (length, original width direction) mm. Step 5) Transverse rolling: The elongated billet obtained in step (4) is divided into two billets according to the blank length calculated by the forging billet length. After heating at 30-60℃ below the β phase transformation point, it is rolled in one pass in 5 passes. The deformation amount per pass is 10-25%. The rolled size is 80 (thickness) × 1450 (width) × 2750 (length) mm.

[0016] Step 6) Quick forging straightening and machining: Heat the rolled forging billet to 750-850℃, straighten it using a quick forging machine, air cool it after forging, and the machined dimensions are 70×1400×2500mm.

[0017] The microstructure of the forged billet in Example 2 was examined, and the results are as follows: Figure 3 , Figure 4 It can be seen that the high-magnification structure in both the horizontal and vertical directions is uniform and well-broken, while the low-magnification structure is blurry.

Claims

1. A method for producing a high homogeneity TA15 titanium alloy thick forge blank, characterized in that, This can be achieved through the following steps: Step 1) Forging: Heat the resistance furnace to 750-850℃, place the furnace, hold for 2-3 hours, raise the temperature to 1100-1200℃, hold for 120-240 minutes, then remove from the furnace and forge on a high-speed forging machine. The upsetting deformation is 30-60%, and the forging is followed by air cooling. Step 2) Single-phase region upsetting and drawing forging: After heating at 30-100℃ above the β phase transformation point, forge 2-3 times, with upsetting deformation of 30-60%, and air cool after forging; Step 3) Two-phase region upsetting and forging: After heating at 30-70℃ below the β phase transformation point, forge 2-5 times, with an upsetting deformation of 40-60%, and air cool after forging; Step 4) Drawing and billet preparation: After heating at 30-70℃ below the β phase transformation point, the billet is drawn 1-2 times. The drawing feed is ≤250mm, the pressing rate is ≥30mm / s, and the total deformation is 50-80%. After forging, the billet is air-cooled and pre-machined to a bright surface, resulting in a billet with a thickness of 2-2.5 times that of the finished forging billet and a width of 0.5-0.6 times that of the finished forging billet. Step 5) Transverse rolling: The billet obtained in step 4) is divided into single-length portions according to the billet length. Then, it is transversely rolled in one pass at 30-60℃ below the β phase transformation point, which is completed in 4-7 passes. The deformation amount in a single pass is 10-25%, and the total deformation amount is 50-80%. Step 6) Straightening and machining: Heat the rolled forging billet to 750-850℃, straighten it using a high-speed forging machine, air cool it after forging, and then machine it according to the product dimensions.

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