A forging method and device for a TC4 titanium alloy bar

Abstract

This invention discloses a forging method for TC4 titanium alloy bars, comprising: obtaining a titanium ingot after a first forging; subjecting the titanium ingot after the first forging to reciprocating heating forging to obtain a titanium ingot after reciprocating heating forging; and subjecting the titanium ingot after reciprocating heating forging to two forging and drawing forging processes to obtain the target titanium alloy bar. This invention, by reciprocating heating forging around the phase transformation point after the initial forging, increases the effect of breaking down coarse β-grains, thereby reducing the number of forging passes, increasing the yield of the forging process, and reducing the power and labor costs of the production process while ensuring the microstructure and properties of the forged bar.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy preparation technology, and in particular to a forging method and apparatus for TC4 titanium alloy bars. Background Technology

[0002] TC4 (Ti-6Al-4V) alloy, as a duplex titanium alloy, has become the most widely used and promoted titanium alloy due to its excellent comprehensive properties and processing characteristics. Especially in the aerospace field, it replaces traditional steel materials, which can significantly reduce aircraft weight. TC4 titanium alloy products cover a variety of materials such as plates, tubes, bars, wires, and tubes. Although the final forming processes are different, forging is an indispensable step in its preparation process, which plays a role in refining grains and improving microstructure.

[0003] Titanium alloys have a narrow hot working temperature window, and the surface of high-temperature ingots is prone to react with hydrogen, oxygen, and nitrogen in the air to form a hard and brittle surface layer. This makes the titanium ingot susceptible to surface defects during forging, requiring grinding after each forging cycle, resulting in wear and increased production costs. However, TC4 titanium alloy forging requires multiple deformations around the phase transformation point to optimize microstructure and properties. Therefore, improving the yield and reducing production costs of TC4 titanium alloy forging while ensuring satisfactory microstructure and properties is a pressing issue. Summary of the Invention

[0004] The purpose of this invention is to provide a forging method and apparatus for TC4 titanium alloy bars, which improves the yield of TC4 titanium alloy forging process and reduces production costs by reducing the number of forging passes.

[0005] To achieve the above objectives, the present invention provides a forging method for TC4 titanium alloy bars, comprising:

[0006] Obtain the titanium ingot after the first forging;

[0007] The titanium ingot after the first forging is subjected to reciprocating heating forging to obtain a titanium ingot after reciprocating heating forging.

[0008] The titanium ingot after reciprocating heating and forging is subjected to two forging processes: initial forging and drawing forging, to obtain the target titanium alloy bar.

[0009] Optionally, the titanium ingot after the first forging is subjected to reciprocating heating forging to obtain a reciprocating heating forged titanium ingot, including:

[0010] The titanium ingot after the first forging is heated to a temperature range below the phase transformation point, and then the titanium ingot after the first forging is obtained through the first upsetting forging.

[0011] The titanium ingot after the first upsetting and forging is heated to a temperature range above the phase transformation point, and then subjected to a second upsetting and forging to obtain the titanium ingot after the second upsetting and forging.

[0012] The titanium ingot after the second upsetting and forging is kept at a temperature below the phase transformation point, and then subjected to a third upsetting and forging to obtain the titanium ingot after the third upsetting and forging.

[0013] Optionally, the upsetting pressure in the first, second, and third upsetting forging processes is 40%-50%, and the height-to-diameter ratio is 1.9-2.1.

[0014] Optionally, the titanium ingot after reciprocating heating forging is subjected to two rounds of forging and drawing forging to obtain the target titanium alloy bar, including:

[0015] The titanium ingot after the third forging is heated to a temperature range below the phase transformation point, and then subjected to a second forging to obtain a titanium ingot after the second forging.

[0016] The titanium ingot after the second forging is heated to a temperature range below the phase transformation point, and then forged a third time to obtain the titanium ingot after the third forging.

[0017] The titanium ingot after the third forging is heated to a temperature range below the phase transformation point, and then the target titanium alloy bar is obtained by drawing and forging.

[0018] Optionally, the first forging, the second forging, and the third forging are all three upsetting and drawing processes, wherein the upsetting pressure is 40%-50% and the drawing height-to-diameter ratio is 1.9-2.1.

[0019] Optionally, the temperature range below the phase transition point is 20-40°C below the phase transition point, and the temperature range above the phase transition point is 50-80°C above the phase transition point.

[0020] Optionally, obtaining the titanium ingot after the first roughing and forging includes:

[0021] The titanium ingot is heated to a preset temperature and then subjected to initial forging to obtain the titanium ingot after the first initial forging.

[0022] Optionally, the preset temperature is 1150℃.

[0023] Optionally, the target titanium alloy bar has a specification of φ250-350mm.

[0024] The present invention also provides a forging apparatus for TC4 titanium alloy bars, comprising:

[0025] The first forging unit is used to obtain titanium ingots after the first forging.

[0026] The reciprocating heating forging unit is used to reciprocate heating forging the titanium ingot after the first blank forging to obtain the titanium ingot after reciprocating heating forging.

[0027] The titanium alloy bar obtaining unit is used to perform two forging processes and drawing forging on the titanium ingot after reciprocating heating forging to obtain the target titanium alloy bar.

[0028] The technical effects and advantages of this invention are as follows:

[0029] This invention provides a forging method for TC4 titanium alloy bars, comprising: obtaining a titanium ingot after a first forging; performing reciprocating heating forging on the titanium ingot after the first forging to obtain a reciprocating heating forged titanium ingot; and performing two forging and drawing forging processes on the reciprocating heating forged titanium ingot to obtain the target titanium alloy bar.

[0030] This invention involves repeated heating and forging around the phase transformation point after the initial forging, which increases the effect of breaking down coarse β crystals. This reduces the number of forging passes, increases the yield of the forging process, and lowers the power and labor costs of the production process, while ensuring the microstructure and properties of the forged bar.

[0031] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0032] Figure 1 A flowchart of the forging method for TC4 titanium alloy bars;

[0033] Figure 2 The image shows a microstructure of the rods prepared in the examples.

[0034] Figure 3 Micrographs of the rods prepared in the comparative example;

[0035] Figure 4 This is a schematic diagram of a forging apparatus for TC4 titanium alloy bars. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0038] To address the shortcomings of existing technologies, this invention discloses a forging method for TC4 titanium alloy bars, such as... Figure 1 As shown. The method includes: obtaining a titanium ingot after a first forging; performing reciprocating heating forging on the titanium ingot after the first forging to obtain a reciprocating heating forged titanium ingot; and performing two forging and drawing forging processes on the reciprocating heating forged titanium ingot to obtain a target titanium alloy bar.

[0039] This invention involves repeated heating and forging around the phase transformation point after the initial forging, which increases the effect of breaking down coarse β crystals. This reduces the number of forging passes, increases the yield of the forging process, and lowers the power and labor costs of the production process, while ensuring the microstructure and properties of the forged bar.

[0040] To better understand this scheme, the forging method of TC4 titanium alloy bars is explained in detail below.

[0041] A forging method for TC4 titanium alloy bars, the specific steps of which are as follows:

[0042] 1. Initial Forging (First Forging): The titanium ingot is heated to 1150℃ in a box-type electric heating furnace (the initial forging temperature of titanium alloy is generally selected 100~250℃ above the phase transformation point, and TC4 is generally selected at 1150℃), and held at that temperature for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into 3 upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0043] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0044] 2. Reciprocating Heating Forging (Second Forging): The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then, it is removed from the furnace and subjected to a single upsetting and drawing process on a 45MN hydraulic press. After the single upsetting and drawing, the ingot is returned to the furnace and heated to 50-80°C above the phase transformation point, held for 3-4 hours, and then subjected to another single upsetting and drawing process on the hydraulic press. The furnace is then cooled to 20-40°C below the phase transformation point, the ingot is returned to the furnace and held for 3-4 hours, and then subjected to another single upsetting and drawing process on the hydraulic press. During the above forging process, the upsetting pressure is controlled at 40%-50%, and the drawing length to height-to-diameter ratio is controlled at 1.9-2.1.

[0045] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0046] 3. Two-phase zone forging (third and fourth forging): The refurbished titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three forging and three drawing processes. After completion, the ingot is scrapped and refurbished.

[0047] After grinding, the ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three forging steps and three drawing steps.

[0048] In the forging process, the upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio during drawing is controlled at 1.9-2.1.

[0049] 4. Drawing and forging (fifth heating): The ground titanium ingot is heated in a box-type electric heating furnace to 20-40℃ below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and drawn and forged on a 45MN hydraulic press to be drawn into bars with a diameter of φ250-350mm.

[0050] To better explain this solution, the present invention also provides embodiments and comparative examples.

[0051] Example

[0052] Step 1: The titanium ingot is heated to 1150℃ in a box-type electric heating furnace and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0053] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0054] Step 2: After grinding, the titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then, it is removed from the furnace and subjected to a one-to-one drawing process on a 45MN hydraulic press. After the one-to-one drawing process, it is returned to the furnace and heated to 50-80°C above the phase transformation point. After holding for 3-4 hours, it is removed from the furnace and subjected to another one-to-one drawing process on the hydraulic press. The heating furnace is then cooled to 20-40°C below the phase transformation point. The titanium ingot is returned to the furnace and held for 3-4 hours. After being removed from the furnace, it is subjected to another one-to-one drawing process on the hydraulic press.

[0055] In the forging process, the upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio during drawing is controlled at 1.9-2.1.

[0056] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0057] Step 3: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0058] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0059] Step 4: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0060] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0061] Step 5: After grinding, the titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held at that temperature for 6-7 hours. Then, it is taken out of the furnace and drawn and forged on a 45MN hydraulic press to be drawn into bars with a diameter of φ250-350mm.

[0062] Comparative example:

[0063] Step 1: The titanium ingot is heated to 1150℃ in a box-type electric heating furnace and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0064] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0065] Step 2: The ground titanium ingot is heated in a box-type electric heating furnace to 50-80°C above the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing stages. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing stage is controlled at 1.9-2.1.

[0066] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0067] Step 3: The ground titanium ingot is heated in a box-type electric heating furnace to 10-30°C above the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0068] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0069] Step 4: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing processes. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing is controlled at 1.9-2.1.

[0070] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0071] Step 5: After grinding, the titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then, it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing stages. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing stage is controlled at 1.9-2.1.

[0072] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0073] Step 6: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing stages. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing stage is controlled at 1.9-2.1.

[0074] After the forging process is completed, the rough stone is removed and the surface defects are repaired by grinding.

[0075] Step 7: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and drawn and forged on a 45MN hydraulic press to be drawn into bars with a diameter of φ250-350mm.

[0076] The difference between the comparative example and the embodiment is that after step 1, conventional forging is used, which adds two more forging passes, for a total of 5 forging passes.

[0077] To verify the performance of titanium alloy bars obtained by the forging method of TC4 titanium alloy bars, the present invention tested the bars obtained in the examples and comparative examples, such as... Figure 2 and Figure 3 As shown in the figure, the microstructure, room temperature tensile properties (annealed state), and high temperature tensile properties (annealed state) of the forged bar obtained in the embodiment are similar to those of the forged bar obtained in the comparative example. The annealing regimes are shown in Tables 1 and 2. Therefore, this invention can reduce the number of forging processes while ensuring the microstructure and properties of TC4 titanium alloy forged bars, thus achieving cost reduction and efficiency improvement.

[0078] Table 1. Room temperature tensile properties of TC4 forged bars with a diameter of Φ250mm

[0079]

[0080] Table 2 High-Temperature (400℃) Tensile Properties of TC4 Forged Bars with Φ250mm Gauge

[0081]

[0082] This invention also provides a forging apparatus for TC4 titanium alloy bars, such as... Figure 4 As shown. The apparatus includes: a first billet forging unit for obtaining a titanium ingot after the first billet forging; a reciprocating heating forging unit for reciprocating heating forging the titanium ingot after the first billet forging to obtain a titanium ingot after reciprocating heating forging; and a titanium alloy bar obtaining unit for performing two billet forgings and drawing forgings on the titanium ingot after reciprocating heating forging to obtain a target titanium alloy bar.

[0083] Since the protection provided by this device is similar to that provided by the method described above, it will not be described in detail here. Please refer to the method description section above for more information.

[0084] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A forging method for TC4 titanium alloy bars, characterized in that, include: Step 1: The titanium ingot is heated to 1150℃ in a box-type electric heating furnace and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing stages. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing stage is controlled at 1.9-2.

1. After the first forging is completed, the blank is discarded and the surface defects are repaired by grinding. Step 2: After grinding, the titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then, it is removed from the furnace and subjected to a one-up-one-drawing process on a 45MN hydraulic press. After the one-up-one-drawing process, it is returned to the furnace and heated to 50-80°C above the phase transformation point. After holding for 3-4 hours, it is removed from the furnace and subjected to another one-up-one-drawing process on the hydraulic press. The heating furnace is then cooled to 20-40°C below the phase transformation point. The titanium ingot is returned to the furnace and held for 3-4 hours. After being removed from the furnace, it is subjected to another one-up-one-drawing process on the hydraulic press. During the above forging process, the upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing length is controlled at 1.9-2.

1. After this forging is completed, the ingot is scrapped and the surface defects are ground. Step 3: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing stages. The upsetting pressure is controlled at 40%-50%, and the height-to-diameter ratio of the drawing stage is controlled at 1.9-2.

1. After the first forging is completed, the blank is discarded and the surface defects are ground. Step 4: The ground titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held for 6-7 hours. Then it is taken out of the furnace and forged on a 45MN hydraulic press. The forging process is divided into three upsetting and drawing stages. The upsetting pressure is controlled at 40%-50%, and the drawing height-to-diameter ratio is controlled at 1.9-2.

1. After the first forging is completed, the blank is discarded and the surface defects are ground. Step 5: After grinding, the titanium ingot is heated in a box-type electric heating furnace to 20-40°C below the phase transformation point and held at that temperature for 6-7 hours. Then, it is taken out of the furnace and drawn and forged on a 45MN hydraulic press to be drawn into bars with a diameter of φ250-350mm.

Images