Titanium or titanium alloy thin strip forming method and equipment

Abstract

The invention belongs to the technical field of metallurgy, particularly relates to a titanium or titanium alloy thin strip forming method and equipment, and solves the problems of complex technological process and high production cost in the titanium or titanium alloy thin strip preparation process. A suspension smelting technology and a double-roller thin strip continuous casting technology are integrated in a vacuum mode, and short-process and non-oxidation preparation of titanium and titanium alloy thin strips is achieved by completing the processes of smelting, casting, cast rolling and rolling in the same vacuum chamber. A suspension smelting technology is adopted to obtain a high-purity titanium alloy melt with uniform components, the high-purity titanium alloy melt is temporarily stored in a preheating tundish and then distributed to a casting roller crystallizer, and the titanium and titanium alloy thin strip with the thickness of 0.5-3 mm is directly formed through the synergistic effect of rapid solidification and large casting and rolling force. The as-cast structure of the prepared titanium alloy thin strip is fine and uniform isometric crystals, element segregation is effectively restrained, the material performance and the yield are remarkably improved, and a new technical approach is provided for efficient and low-cost industrial application of titanium and titanium alloy thin strips.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and specifically relates to a method and equipment for forming titanium or titanium alloy thin strips. Background Technology

[0002] Titanium and titanium alloys possess excellent high-temperature mechanical properties and corrosion resistance, making them widely used in key fields such as aerospace, defense, and rail transportation. Titanium alloy strips are crucial materials for producing components such as honeycomb seals, heating grids, and bipolar plates for new energy fuels. However, current production efficiency and yield of titanium alloy strips remain low, particularly in ultra-thin and ultra-wide strips, urgently requiring process innovation and technological breakthroughs. Currently, mature industrial technologies for smelting titanium alloys mainly include electron beam cold hearth melting, vacuum consumable arc melting, and non-consumable arc solidification melting. Furthermore, subsequent processing methods also face challenges such as high resistance to high-temperature deformation and narrow processing windows.

[0003] Twin-roll strip casting is a cutting-edge technology in the field of metal continuous casting. Molten metal flows into a molten pool composed of casting rolls and side sealing plates, combining traditional casting and rolling processes into one, directly obtaining strips 1-5 mm thick. It offers the advantages of a short process and sub-rapid solidification. Currently, numerous patents have reported on strip casting technology for steel materials, such as Chinese invention patent publications CN117926107A, CN120888735A, CN118996234A, CN115233080A, and CN115216704A. However, research on strip casting in the field of titanium alloys is relatively limited, mainly due to the issue of furnace flow matching. Titanium alloys have high requirements for melting, especially the homogeneity and purity of the melt composition. To address this issue, suspension melting technology can significantly promote alloy composition homogenization and reduce segregation.

[0004] Chinese invention patent publication numbers CN107058875A, CN107245647A, CN107164693A, CN112475254A, and CN112180997A relate to a thin-strip continuous casting forming technology for silicon steel strip, wherein the liquid level height is 100~180mm, and the heat transfer coefficient of silicon steel is approximately 50~100 W / m. 2 ·K, while titanium and titanium alloys have 16~22 W / m 2 The K content is significantly lower than that of iron-based or nickel-based alloys, so the forming process of titanium alloys requires a lower liquid level, a larger casting and rolling force, and a greater side sealing plate clamping force. This, combined with environmental atmosphere and pressure control, enables flexible regulation of solidification cooling rate.

[0005] Chinese invention patent publication numbers CN109967703A, CN109957732A, and CN109822067A relate to methods for the continuous preparation of amorphous thin strips. In the continuous preparation process of amorphous thin strips, amorphous thin strips with a thickness ≤800 µm and a width ≤100 mm are prepared by using high roller speed and no side sealing.

[0006] Chinese invention patent publication CN108067596A proposes a method for preparing uniformly microstructured TiAl alloy slabs by thin strip casting and rolling, and Chinese invention patent publication CN106048303A proposes a method for preparing large-size titanium-aluminum alloy plates. Their main features are the improvement of microstructure inhomogeneity and cracking problems in traditional cladding hot rolling processes through synergistic control of melt superheating, rolling, and cooling processes. These methods offer advantages such as near-net-shape forming, simplified processes, and lower costs, making them suitable for the efficient preparation of large-size high-performance TiAl alloy plates. It should be noted that this method involves casting under non-vacuum conditions, which may degrade the performance of oxidation-sensitive alloys.

[0007] In summary, titanium and titanium alloys have extremely high requirements for compositional uniformity and purity during the smelting process. Existing smelting technologies are prone to crucible contamination and compositional segregation. Furthermore, existing thin strip continuous casting technology has not been integrated with the high-purity smelting technology for titanium alloys, making it impossible to achieve full-process production of titanium alloy thin strips and difficult to stably prepare high-performance titanium and titanium alloy thin strips. Summary of the Invention

[0008] In view of the high requirements for uniformity and purity of smelting composition of titanium and titanium alloys, as well as the serious segregation during solidification, high resistance to high-temperature deformation, and narrow processing window, the purpose of this invention is to provide a method and equipment for forming titanium or titanium alloy thin strips, so as to solve the problems of complex process flow and high production cost in the preparation of titanium and titanium alloy thin strips.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A method for forming titanium or titanium alloy thin strips includes the following steps:

[0011] (1) Before the titanium alloy is melted and cast, the vacuum chamber is evacuated in stages using a mechanical pump, a Roots pump and a booster pump until the pressure is 1×10⁻⁶. -3 ~3×10 -3 Pa, fill with argon or helium to a pressure of 1×10⁻⁶. 4 ~5×10 4 Pa;

[0012] (2) Use a suspension melting furnace to melt titanium or titanium alloy to obtain a titanium or titanium alloy melt with uniform composition. The heating temperature is 1400~2500 ℃, and the alloy is held at the molten state for 5~10 min.

[0013] (3) After the melting is completed, the graphite tundish is preheated online to 1100~1250 ℃ before casting. Then the titanium or titanium alloy melt in the suspension melting furnace is poured into the graphite tundish that has reached the casting temperature.

[0014] (4) The titanium or titanium alloy melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the water outlet, and the molten pool liquid level height is 3~160 mm.

[0015] (5) The alloy melt in the molten pool is rapidly solidified by the casting roll crystallizer. By controlling the casting speed, casting force and casting superheat, a titanium or titanium alloy strip with a thickness of 0.5~3 mm is obtained. The casting speed is 10~40 m / min, the casting force is 10~50 kN, and the casting superheat is 10~50 ℃.

[0016] (6) After the thin strip solidifies, it is fed through the arc-shaped guide plate and the pinch roller to the winding-type winding device in the winding-up sealed chamber.

[0017] In the titanium or titanium alloy thin strip forming method, in step (1), a mechanical pump is used to evacuate the vacuum chamber to a pressure of 1×10⁻⁶. 2 ~3×10 2 After Pa, turn on the Roots pump and booster pump to evacuate to a pressure of 1×10⁻⁶. -3 ~3×10 -3 Pa, fill with argon or helium to a pressure of 1×10⁻⁶. 4 ~5×10 4 Pa creates an oxidation-free protective environment, and the gas volume is adjusted to control the cooling rate of titanium or titanium alloy strips at 50~200 K / s.

[0018] In the titanium or titanium alloy strip forming method, in step (2), the suspension melting furnace is made of oxygen-free copper and is equipped with water cooling for real-time cooling; in order to ensure uniform composition, the melting times are ≥3 times.

[0019] In the titanium or titanium alloy strip forming method, in step (3), the graphite intermediate ladle is made of isostatic graphite material and is coated with yttrium oxide coating inside to reduce contamination of the titanium or titanium alloy melt. The heating method is online induction heating and the tilting speed of the suspension melting furnace is 500~1000 r / min.

[0020] In the titanium or titanium alloy thin strip forming method, in step (4), the water outlet is a non-immersion water outlet made of isostatic graphite material, with yttrium oxide coating inside. The diameter of the water outlet is 10~20 mm, and the bottom of the water outlet is located at the center of the casting roll crystallizer. Side sealing plates are arranged on both sides of the casting roll crystallizer. The side sealing plates are made of graphite material, with yttrium oxide coating inside. The side sealing plates are controlled by hydraulic cylinders, and their clamping force is 10~20 kN.

[0021] In the titanium or titanium alloy thin strip forming method, in step (4), the diameter of the casting roll crystallizer is 500 mm and the width is 100~600 mm. In order to meet the cooling rate requirements of different titanium or titanium alloy forming, two casting roll materials, high-strength alloy steel and beryllium copper with internal cooling water, are used. The cooling rate of alloy solidification is 100~1000 K / s.

[0022] In the titanium or titanium alloy strip forming method, in step (5), the casting temperature is 1550~1750 ℃; in step (6), the strip winding temperature is 800~1200 ℃.

[0023] A titanium or titanium alloy strip forming equipment includes a vacuum chamber, a suspension melting furnace, a graphite tundish, a sprue, a side sealing plate, a casting roll crystallizer, an arc-shaped guide plate, pinch rollers, and a winding-up device. The specific structure is as follows: the vacuum chamber integrates a melting chamber, a casting and rolling chamber, and a winding-up sealed chamber. The melting chamber is located at the top of the casting and rolling chamber, and the winding-up sealed chamber is located on one side of the casting and rolling chamber. The melting chamber contains a suspension melting furnace and a graphite tundish, while the casting and rolling chamber contains a sprue, a side sealing plate, and a casting roll crystallizer. The system includes an arc-shaped guide plate, pinch rollers, and a winding-type winding device in the sealed take-up chamber. The suspension melting furnace is located in the upper part of the vacuum chamber, and the graphite tundish is located directly below the suspension melting furnace. The water outlet is installed at the bottom of the graphite tundish, directly opposite the molten pool formed by the casting roll crystallizer and the side sealing plate. The arc-shaped guide plate is located below the casting roll crystallizer, and the pinch rollers are located on one side of the arc-shaped guide plate. After the thin strip exits the roll, it is sent through the arc-shaped guide plate and the pinch rollers to the winding-type winding device in the sealed take-up chamber.

[0024] The titanium or titanium alloy strip forming equipment has side sealing plates symmetrically arranged on both sides of the casting roll crystallizer, forming a closed triangular molten pool together with the casting roll crystallizer. The side sealing plates are kept in close contact with the casting roll crystallizer by a clamping mechanism to prevent the melt from leaking from both sides of the casting roll crystallizer. The casting roll crystallizer consists of two casting rolls rotating in opposite directions. The inside of the roll body is designed with cooling water channels, and a rapid cooling rate of 50~200K / s is achieved by regulating the flow rate and pressure of the cooling water.

[0025] The titanium or titanium alloy strip forming equipment has a 90° arc-shaped structure on the surface of the arc-shaped guide plate. The newly formed strip is guided by the arc-shaped guide plate to transition at a 90° angle to the pinch roller. The pinch roller consists of two sets of upper and lower rollers. The strip is conveyed from the arc-shaped guide plate to the winding device by the clamping force.

[0026] The design concept of this invention is:

[0027] This invention integrates suspension melting technology with twin-roll thin strip casting technology in a fully vacuum system, constructing a short-process preparation system for pure melting, oxidation-free casting, rapid solidification, and direct forming. Addressing the requirements for melting purity and compositional uniformity of titanium and titanium alloys, a crucible-free suspension melting technology is employed, combined with multiple melting and holding processes, to achieve high purity and high compositional uniformity of the melt. Considering the strong oxidation sensitivity of titanium and titanium alloys, the entire system of melting, casting, rolling, and coiling is integrated into a single vacuum chamber, achieving oxidation-free protection throughout the process. Simultaneously, the solidification cooling rate of titanium and titanium alloys can be flexibly controlled by adjusting the atmosphere and pressure within the vacuum chamber. Addressing the low heat transfer coefficient and high deformation resistance characteristics of titanium and titanium alloys, core process parameters such as molten pool level, rolling speed, and rolling force are precisely designed. Through rapid solidification in two casting roll crystallizers and the grain refinement effect of high rolling force, the problems of solidification segregation and forming difficulties in titanium and titanium alloys are solved, ultimately achieving short-process, low-cost, and stable preparation of high-quality titanium and titanium alloy thin strips.

[0028] This invention relates to titanium and titanium alloy thin strip forming equipment that integrates a suspension melting furnace and a thin strip continuous casting machine into the same large vacuum chamber. This allows the alloy melting and casting processes to be carried out under oxidation-free conditions, improving the oxidation problem of the alloy during processing. Because the atmosphere and ambient pressure can be adjusted over a wide range within the vacuum chamber, the solidification rate of the alloy can be controlled, enabling the short-process preparation of high-quality titanium and titanium alloy thin strips. Specifically, the equipment mainly consists of five parts: a vacuum system, a melting system, a casting system, a casting and rolling system, and a strip collection system. It can directly form titanium and titanium alloy melt into thin strips of 0.5~3 mm, eliminating the conventional processes of ingot homogenization, forging, and hot rolling, providing a completely new processing method for the short-process preparation of high-quality titanium and titanium alloy thin strips.

[0029] This invention, through the design of a side sealing plate and a casting roll crystallizer with a width of 100-600 mm, enables the production of titanium and titanium alloy strips with widths of 100-600 mm, meeting the practical application requirements of wide titanium and titanium alloy strips. Furthermore, based on a deep understanding of the fundamentally different solidification behaviors of titanium and titanium alloy strips, it proposes technical solutions for liquid level height, casting and rolling force, and side sealing control.

[0030] Therefore, this invention employs a method combining suspension melting and thin strip continuous casting. Through a short process of pure melting, rapid solidification, and direct forming, it can achieve high purity, fine grain structure, excellent mechanical properties, and low-cost preparation of alloy thin plates, making it particularly suitable for the industrial application of titanium and titanium alloy thin strip materials.

[0031] Compared with the existing technology, the present invention has the following beneficial technical effects:

[0032] 1. A method combining suspension melting technology with a thin strip casting and rolling experimental platform. Compared with traditional melting methods, this invention integrates suspension melting technology with thin strip casting and rolling technology. During suspension melting, the melt does not come into contact with the inner wall of the suspension melting furnace, reducing the chance of the furnace contaminating the melt. Furthermore, the intense electromagnetic stirring during suspension melting significantly promotes the diffusion of chemical elements in the melt, improving the compositional uniformity of the material. This achieves the preparation of high-purity and high-compositional uniformity titanium and titanium alloy melts, significantly reducing elemental segregation.

[0033] 2. Oxidation-free casting. This invention constructs a large-scale integrated vacuum chamber, placing the melting system, casting system, and strip continuous casting machine in the same vacuum chamber. This achieves oxidation-free protection throughout the entire process of melting, casting, casting and rolling, and coiling, completely solving the oxidation problem in the processing of titanium and titanium alloys, and ensuring the purity and performance stability of the strip.

[0034] 3. Short-process preparation technology. This invention realizes a short-process preparation of titanium and titanium alloy strips. The alloy melt is rapidly solidified into strips of the target specifications through a casting roll crystallizer, eliminating the conventional processes of ingot homogenization, forging, and hot rolling, achieving one-step direct forming, which significantly reduces the preparation cost and cycle time.

[0035] 4. Grain Refinement. During the alloy casting and rolling process of this invention, a large casting and rolling force is used to cause the growing dendrite arms to fracture, and these fragments become new nucleation points; at the same time, its extremely high cooling rate promotes the refinement of the solidification structure and the homogenization of composition, effectively improving macroscopic segregation, and providing a brand-new processing method for the efficient preparation of titanium and titanium alloy thin strips.

[0036] 5. Based on the solidification characteristics of titanium and titanium alloys, the present invention designed core process parameters. Through the synergistic effect of rapid solidification in the casting roll crystallizer and large casting and rolling force, the solidification structure of titanium and titanium alloys was significantly refined. The as-cast structure of the prepared titanium and titanium alloy strips is uniform and fine equiaxed crystals with an average grain size of 68 μm or even smaller, which effectively improves macroscopic segregation and enhances the mechanical properties of the strips.

[0037] 6. This invention can stably prepare wide titanium and titanium alloy strips with a width of 100~600mm and a thickness of 0.5~3mm, which can meet the application requirements of large-size titanium and titanium alloy strips in key fields such as aerospace, new energy, and national defense. At the same time, by adjusting the vacuum chamber atmosphere pressure, the solidification cooling rate of 50~200K / s can be flexibly controlled to meet the forming requirements of different grades of titanium and titanium alloys, thus broadening the process window. Attached Figure Description

[0038] Figure 1 This is a physical diagram of a titanium and titanium alloy thin strip forming equipment proposed in this invention. Reference numerals in the figure: 1 Vacuum chamber, 2 Suspension melting furnace, 3 Graphite tundish, 4 Drain outlet, 5 Side sealing plate, 6 Casting roll crystallizer, 7 Thin strip, 8 Arc-shaped guide plate, 9 Pinch roller, 10 Winding-up device.

[0039] Figure 2 This is a microstructure diagram of the TA1 alloy in Example 1.

[0040] Figure 3 This is a microstructure diagram of the TB5 alloy in Example 4. Detailed Implementation

[0041] In its specific implementation, this invention proposes a method for forming titanium and titanium alloy thin strips, the specific steps of which are as follows:

[0042] Step 1: Before melting and casting titanium and titanium alloys, a mechanical pump is used to evacuate the vacuum chamber to a pressure of 1×10⁻⁶. 2 ~3×10 2 After Pa, start the Roots pump and booster pump to pump to 1×10 -3 ~3×10 -3 Pa, fill with high-purity argon or helium to a pressure of 1×10⁻⁶. 4 ~5×10 4 Pa creates an oxidation-free protective environment, and the gas volume is adjusted to control the cooling rate of titanium and titanium alloy strips at 50~200 K / s.

[0043] Step 2: Titanium and titanium alloys are smelted in a suspension melting furnace at a heating temperature of 1400~2500 ℃, and the melting is carried out ≥3 times. After the alloy reaches the molten state, it is held at the temperature for 5~10 min.

[0044] Step 3: Before casting, preheat the graphite tundish online to 1100~1250 ℃, and then pour the titanium and titanium alloy melt in the suspension melting furnace into the graphite tundish that has reached the casting temperature at a pouring speed of 500~1000 r / min.

[0045] Step 4: The titanium and titanium alloy melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the water outlet. The liquid level of the molten pool is 3~160 mm.

[0046] Step 5: The alloy melt in the molten pool is rapidly solidified in the casting roll crystallizer to form a thin strip of 0.5~3 mm. The casting speed is 10~40 m / min, the casting force is controlled at 10~50 kN, and the casting superheat is 10~50 ℃.

[0047] Step 6: After the thin strip solidifies, it is fed through the arc-shaped guide plate and the pinch rollers to the winding-type winding device in the sealed winding chamber.

[0048] like Figure 1 As shown, this invention proposes a titanium and titanium alloy thin strip forming equipment, mainly including a vacuum chamber 1, a suspension melting furnace 2, a graphite tundish 3, a sprue 4, a side sealing plate 5, a casting roll crystallizer 6, an arc-shaped guide plate 8, a pinch roll 9, and a winding-type take-up device 10, the specific structure of which is as follows:

[0049] The melting chamber, casting and rolling chamber, and tape-receiving sealed chamber are integrated into the same vacuum chamber 1. The melting chamber is located on top of the casting and rolling chamber, and the tape-receiving sealed chamber is located on one side of the casting and rolling chamber. The melting chamber is equipped with a suspension melting furnace 2 and a graphite tundish 3. The casting and rolling chamber is equipped with a water outlet 4, a side sealing plate 5, a casting roll crystallizer 6, an arc-shaped guide plate 8, and a pinch roller 9. The tape-receiving sealed chamber is equipped with a winding-type winding device 10. This achieves oxidation-free protection of titanium and titanium alloys throughout the entire process from melting, casting, casting and rolling to conveying, and completely avoids oxidation pollution of titanium and titanium alloys when they come into contact with air at high temperatures.

[0050] The suspension melting furnace 2 is located in the upper part of the vacuum chamber 1. It adopts crucible-free contact suspension melting technology, which melts titanium and titanium alloy raw materials through electromagnetic induction heating. At the same time, it uses electromagnetic stirring to promote uniform diffusion of alloying elements, avoiding the contamination of the melt by the crucible in traditional melting methods, and providing high-purity and high compositional uniformity titanium and titanium alloy melt for subsequent casting and rolling.

[0051] The graphite tundish 3 is positioned directly below the suspension melting furnace 2 to buffer the titanium and titanium alloy melt poured out of the suspension melting furnace 2, and to homogenize the temperature and stabilize the flow rate of the melt. The graphite tundish 3 is equipped with an online preheating component, which can preheat the melt to 1100~1250℃ before casting, preventing the melt from becoming less fluid or solidifying and clogging due to a sudden drop in temperature before entering the molten pool.

[0052] The flow outlet 4 is installed at the bottom of the graphite tundish 3, directly facing the molten pool formed by the casting roll crystallizer 6 and the side sealing plate 5 below. It is used to uniformly and stably distribute the titanium and titanium alloy melt in the graphite tundish into the molten pool, ensuring the uniformity of the melt distribution on the casting roll crystallizer 6, and avoiding thin strip thickness deviation or forming defects due to uneven distribution.

[0053] Side sealing plates 5 are symmetrically arranged on both sides of the casting roll crystallizer 6, forming a closed triangular molten pool together with the casting roll crystallizer 6 to prevent the molten material from leaking from both sides of the casting roll crystallizer 6. The side sealing plates 5 are kept in close contact with the casting roll crystallizer 6 by a tightening mechanism to ensure the sealing and stability of the molten pool.

[0054] The casting roll crystallizer 6 consists of two counter-rotating casting rolls. The roll body is designed with cooling water channels, which can achieve a rapid cooling rate of 50~200K / s by adjusting the cooling water flow rate and pressure. The melt solidifies rapidly on the surface of the casting roll crystallizer 6, and at the same time undergoes plastic deformation under the action of casting and rolling force, directly forming a thin strip with a thickness of 0.5~3mm, realizing near-net-shape forming of casting and rolling integration.

[0055] The arc-shaped guide plate 8 is located below the casting roll crystallizer 6. The surface of the arc-shaped guide plate 8 is a 90° arc structure, which is used to guide the newly formed thin strip 7 to smoothly transition to the pinch roll 9 at 90°, so as to avoid the thin strip bending, wrinkling or breaking due to its own weight or stress, and to ensure the stability of the thin strip conveying process.

[0056] The pinch roller 9 consists of two sets of upper and lower rollers. It uses clamping force to smoothly transport the thin strip 7 from the arc-shaped guide plate 8 to the winding device 10. At the same time, it can perform slight straightening treatment on the thin strip to improve the flatness and surface quality of the thin strip.

[0057] The take-up winding device 10 is installed in a sealed take-up chamber to maintain an oxidation-free environment. It is used to wind the continuously formed thin strip 7 into a roll for easy subsequent storage, transportation and processing.

[0058] The smelting and casting of titanium and titanium alloys are carried out in an integrated vacuum chamber 1. The molten titanium and titanium alloy melt in the suspension melting furnace 2 is rapidly poured into the online preheated graphite tundish 3. After flowing into the triangular molten pool formed by the side sealing plate 5 and the casting roll crystallizer 6 through the water outlet 4, it rapidly solidifies to form a thin strip 7 with a thickness of 0.5~3.0 mm. The width of the thin strip 7 can be adjusted according to the width of the roll body of the casting roll crystallizer 6 (100~600 mm). The as-cast microstructure is uniform and fine equiaxed crystals with no obvious macroscopic segregation. After exiting the roll, the thin strip 7 is sent through the arc-shaped guide plate 8 and the pinch roller 9 to the winding-type winding device 10 in the winding-up sealed chamber to complete the winding. The entire process is completed in the non-oxidizing environment of the vacuum chamber 1.

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0060] Example 1

[0061] In this embodiment, a TA1 thin strip forming method and equipment are performed according to the following steps:

[0062] 1. Use a mechanical pump to evacuate the vacuum chamber (melting chamber, casting and rolling chamber) to a pressure of 2×10⁻⁶. 2 After Pa, turn on the Roots pump and booster pump to evacuate to a pressure of 1×10⁻⁶. -3 Pa, filled with high-purity argon gas (99.999% volume purity) until the pressure reaches 2 × 10⁻⁶. 4 Pa.

[0063] 2. The alloy melt was smelted using suspension melting technology according to the composition of industrial pure titanium TA1. The heating temperature was 1708℃. After the alloy reached the molten state, it was held at the temperature for 10 minutes. In order to ensure uniform composition, the melting was carried out 3 times.

[0064] 3. Before casting, the graphite tundish is preheated online to 1200 ℃. Then, the TA1 melt in the suspension melting furnace is poured into the graphite tundish that has reached the casting temperature at a pouring speed of 900 r / min.

[0065] 4. The TA1 melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the flow outlet, and the liquid level of the molten pool is 90 mm.

[0066] 5. After online preheating, the alloy melt is poured into a triangular molten pool formed by the casting roll crystallizer and the side sealing plate. The alloy melt is rapidly solidified in the casting roll crystallizer to form a 1.0 mm thin strip. The casting speed is 40 m / min, the casting force is controlled at 30 kN, and the casting superheat is 40 ℃.

[0067] 6. After the TA1 thin strip solidifies, it is fed through an arc-shaped guide plate and pinch rollers to the winding-type winding device in the sealed winding chamber.

[0068] In this embodiment, the strip is 3000 mm long, 200 mm wide, and 1.0 mm thick.

[0069] like Figure 2 As shown in the microstructure diagram of the TA1 strip, the as-cast microstructure consists of numerous fine equiaxed grains with an average grain size of approximately 68 μm. The grain size distribution is concentrated, with no obvious coarse columnar grain regions or severe macroscopic segregation. This indicates that the rapid solidification of the casting roll mold, combined with the high casting rolling force, breaks up the primary dendrites, promotes the nucleation and growth of equiaxed grains, effectively suppresses elemental segregation during the solidification process of the titanium alloy, and improves the microstructure uniformity and mechanical property stability of the strip.

[0070] Example 2

[0071] In this embodiment, a TA1 thin strip forming method and equipment are performed according to the following steps:

[0072] 1. Use a mechanical pump to evacuate the vacuum chamber (melting chamber, casting and rolling chamber) to a pressure of 2×10⁻⁶. 2 After Pa, turn on the Roots pump and booster pump to evacuate to a pressure of 1×10⁻⁶. -3 Pa, filled with high-purity argon gas (99.999% volume purity) until the pressure reaches 2 × 10⁻⁶. 4 Pa.

[0073] 2. The alloy melt was smelted using suspension melting technology with the composition set according to industrial pure titanium TA1. The heating temperature was 1688℃. After the alloy reached the molten state, it was held at the temperature for 8 minutes. In order to ensure uniform composition, the melting was carried out 4 times.

[0074] 3. Before casting, the graphite tundish is preheated online to 1200 ℃. Then, the TA1 melt in the suspension melting furnace is poured into the graphite tundish that has reached the casting temperature at a pouring speed of 700 r / min.

[0075] 4. The TA1 melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the flow outlet, and the liquid level of the molten pool is 110 mm.

[0076] 5. After online preheating, the alloy melt is poured into a triangular molten pool formed by the casting roll crystallizer and the side sealing plate. The alloy melt is rapidly solidified in the casting roll crystallizer to form a 2.0 mm thin strip. The casting speed is 25 m / min, the casting force is controlled at 40 kN, and the casting superheat is 20 ℃.

[0077] 6. After the TA1 thin strip solidifies, it is fed through an arc-shaped guide plate and pinch rollers to the winding-type winding device in the sealed winding chamber.

[0078] In this embodiment, the strip is 2400 mm long, 200 mm wide, and 2.0 mm thick. The as-cast microstructure consists of numerous fine equiaxed crystals with an average grain size of approximately 85 μm.

[0079] Example 3

[0080] In this embodiment, a TA1 thin strip forming method and equipment are performed according to the following steps:

[0081] 1. Use a mechanical pump to evacuate the vacuum chamber (melting chamber, casting and rolling chamber) to a pressure of 2×10⁻⁶. 2 After Pa, turn on the Roots pump and booster pump to evacuate to a pressure of 1×10⁻⁶. -3 Pa, filled with high-purity argon gas (99.999% volume purity) until the pressure reaches 2 × 10⁻⁶. 4 Pa.

[0082] 2. The alloy melt was smelted using suspension melting technology with the composition set according to industrial pure titanium TA1. The heating temperature was 1678℃. After the alloy reached the molten state, it was held at the temperature for 5 minutes. In order to ensure uniform composition, the melting was carried out 5 times.

[0083] 3. Before casting, the graphite tundish is preheated online to 1200 ℃. Then, the TA1 melt in the suspension melting furnace is poured into the graphite tundish that has reached the casting temperature at a pouring speed of 600 r / min.

[0084] 4. The TA1 melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the flow outlet, and the liquid level of the molten pool is 125 mm.

[0085] 5. After online preheating, the alloy melt is poured into a triangular molten pool formed by the casting roll crystallizer and the side sealing plate. The alloy melt is rapidly solidified in the casting roll crystallizer to form a 2.5 mm thin strip. The casting speed is 10 m / min, the casting force is controlled at 50 kN, and the casting superheat is 10 ℃.

[0086] 6. After the TA1 thin strip solidifies, it is fed through an arc-shaped guide plate and pinch rollers to the winding-type winding device in the sealed winding chamber.

[0087] In this embodiment, the strip is 2000 mm long, 200 mm wide, and 2.5 mm thick. The as-cast microstructure consists of numerous fine equiaxed crystals with an average grain size of approximately 110 μm.

[0088] Example 4

[0089] In this embodiment, a method and equipment for forming TB5 titanium alloy thin strips are performed according to the following steps:

[0090] 1. Use a mechanical pump to evacuate the vacuum chamber (melting chamber, casting and rolling chamber) to a pressure of 1×10⁻⁶. 2 After Pa, turn on the Roots pump and booster pump to evacuate to a pressure of 1.5 × 10⁻⁶. -3 Pa, high-purity argon gas (99.999% volume purity) is introduced until the pressure reaches 1.5 × 10⁻⁶. 4 Pa.

[0091] 2. The alloy melt was smelted using suspension melting technology according to the composition set for TB5 alloy. The heating temperature was 1680 ℃. After the alloy reached the molten state, it was held at the temperature for 10 min. In order to ensure uniform composition, the melting was carried out 4 times.

[0092] 3. Before casting, the graphite tundish is preheated online to 1230 ℃. Then, the TB5 melt in the suspension melting furnace is poured into the graphite tundish that has reached the casting temperature at a pouring speed of 800 r / min.

[0093] 4. The TB5 melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the flow outlet, and the liquid level of the molten pool is 100 mm.

[0094] 5. After online preheating, the alloy melt is poured into a triangular molten pool formed by the casting roll crystallizer and the side sealing plate. The alloy melt is rapidly solidified in the casting roll crystallizer to form a 1.6 mm thin strip. The casting speed is 35 m / min, the casting force is controlled at 35 kN, and the casting superheat is 10 ℃.

[0095] 6. After solidification, the TB5 thin strip is fed through an arc-shaped guide plate and pinch rollers to a winding-type winding device in the sealed winding chamber.

[0096] In this embodiment, the strip is 2500 mm long, 200 mm wide, and 1.6 mm thick.

[0097] like Figure 3 As shown in the image, the morphology of the TB5 thin strip shows that the as-cast structure consists of a large number of fine equiaxed crystals with an average grain size of approximately 35 μm.

[0098] The results show that the present invention provides a method and equipment for forming titanium and titanium alloy thin strips, whose extremely high cooling rate can refine the solidification structure and improve elemental segregation. This near-net-shape preparation method eliminates the ingot forging, cladding, heat treatment, and hot rolling processes in cladding rolling, significantly reducing the preparation difficulty and cost, and providing a new processing approach for the mass production of titanium and titanium alloy thin strips.

Claims

1. A method for forming titanium or titanium alloy thin strips, characterized in that, Includes the following steps: (1) Before the titanium alloy is melted and cast, the vacuum chamber is evacuated in stages using a mechanical pump, a Roots pump and a booster pump until the pressure is 1×10⁻⁶. -3 ~3×10 -3 Pa, fill with argon or helium to a pressure of 1×10⁻⁶. 4 ~5×10 4 Pa; (2) Use a suspension melting furnace to melt titanium or titanium alloy to obtain a titanium or titanium alloy melt with uniform composition. The heating temperature is 1400~2500 ℃, and the alloy is held at the molten state for 5~10 min. (3) After the melting is completed, the graphite tundish is preheated online to 1100~1250 ℃ before casting. Then the titanium or titanium alloy melt in the suspension melting furnace is poured into the graphite tundish that has reached the casting temperature. (4) The titanium or titanium alloy melt in the graphite tundish flows into the molten pool formed by the casting roll crystallizer and the side sealing plates on both sides through the water outlet, and the molten pool liquid level height is 3~160 mm. (5) The alloy melt in the molten pool is rapidly solidified by the casting roll crystallizer. By controlling the casting speed, casting force and casting superheat, a titanium or titanium alloy strip with a thickness of 0.5~3 mm is obtained. The casting speed is 10~40 m / min, the casting force is 10~50 kN, and the casting superheat is 10~50 ℃. (6) After the thin strip solidifies, it is fed through the arc-shaped guide plate and the pinch roller to the winding-type winding device in the winding-up sealed chamber.

2. The method for forming titanium or titanium alloy thin strips according to claim 1, characterized in that, In step (1), a mechanical pump is used to evacuate the vacuum chamber to a pressure of 1×10⁻⁶. 2 ~3×10 2 After Pa, turn on the Roots pump and booster pump to evacuate to a pressure of 1×10⁻⁶. -3 ~3×10 -3 Pa, fill with argon or helium to a pressure of 1×10⁻⁶. 4 ~5×10 4 Pa creates an oxidation-free protective environment, and the gas volume is adjusted to control the cooling rate of titanium or titanium alloy strips at 50~200 K / s.

3. The method for forming titanium or titanium alloy thin strips according to claim 1, characterized in that, In step (2), the suspension melting furnace is made of oxygen-free copper and is equipped with water cooling for real-time cooling; in order to ensure uniform composition, the melting process is ≥3 times.

4. The method for forming titanium or titanium alloy thin strips according to claim 1, characterized in that, In step (3), the graphite intermediate ladle is made of isostatic graphite material and is coated with yttrium oxide coating inside to reduce contamination of titanium or titanium alloy melt. Its heating method is online induction heating and the tilting speed of the suspension melting furnace is 500~1000 r / min.

5. The method for forming titanium or titanium alloy thin strips according to claim 1, characterized in that, In step (4), the water outlet is a non-immersion type made of isostatic graphite material, with yttrium oxide coating inside. The diameter of the water outlet is 10~20mm, and the bottom of the water outlet is located at the center of the casting roll crystallizer. Side sealing plates are arranged on both sides of the casting roll crystallizer. The side sealing plates are made of graphite material, with yttrium oxide coating inside. The side sealing plates are controlled by hydraulic cylinders, and their clamping force is 10~20 kN.

6. The method for forming titanium or titanium alloy thin strips according to claim 1, characterized in that, In step (4), the diameter of the casting roll crystallizer is 500 mm and the width is 100~600 mm. In order to meet the cooling rate requirements of different titanium or titanium alloy forming, two casting roll materials, high-strength alloy steel and beryllium copper, are used. The cooling rate of alloy solidification is 100~1000 K / s.

7. The method for forming titanium or titanium alloy thin strips according to claim 1, characterized in that, In step (5), the casting temperature is 1550~1750 ℃; in step (6), the strip winding temperature is 800~1200 ℃.

8. A titanium or titanium alloy strip forming apparatus for use in the method according to any one of claims 1 to 7, characterized in that, The system includes a vacuum chamber, a suspension melting furnace, a graphite tundish, a sprue, side sealing plates, a casting roll crystallizer, an arc-shaped guide plate, pinch rollers, and a winding-up device. The specific structure is as follows: The vacuum chamber integrates a melting chamber, a casting and rolling chamber, and a winding-up sealed chamber. The melting chamber is located at the top of the casting and rolling chamber, and the winding-up sealed chamber is located on one side of the casting and rolling chamber. The melting chamber contains a suspension melting furnace and a graphite tundish. The casting and rolling chamber contains a sprue, side sealing plates, a casting roll crystallizer, an arc-shaped guide plate, and a winding-up device. The conveying roll and the sealed take-up chamber are equipped with a winding-type winding device; the suspension melting furnace is located in the upper area of ​​the vacuum chamber, the graphite tundish is located directly below the suspension melting furnace, the water outlet is installed at the bottom of the graphite tundish, directly facing the molten pool formed by the casting roll crystallizer and the side sealing plate below, the arc-shaped guide plate is located below the casting roll crystallizer, and the pinch roller is located on one side of the arc-shaped guide plate. After the thin strip exits the roll, it is sent through the arc-shaped guide plate and the pinch roller to the winding-type winding device in the sealed take-up chamber.

9. The titanium or titanium alloy thin strip forming equipment according to claim 8, characterized in that, The side sealing plates are symmetrically arranged on both sides of the casting roll crystallizer, forming a closed triangular molten pool together with the casting roll crystallizer. The side sealing plates are kept in close contact with the casting roll crystallizer by a clamping mechanism to prevent the melt from leaking from both sides of the casting roll crystallizer. The casting roll crystallizer consists of two casting rolls rotating in opposite directions. The inside of the roll body is designed with cooling water channels, and a rapid cooling rate of 50~200K / s is achieved by regulating the flow rate and pressure of the cooling water.

10. The titanium or titanium alloy thin strip forming equipment according to claim 8, characterized in that, The surface of the arc-shaped guide plate has a 90° arc structure. The newly formed thin strip is guided by the arc-shaped guide plate to transition at a 90° angle to the pinch roller. The pinch roller consists of two sets of upper and lower rollers. The thin strip is conveyed from the arc-shaped guide plate to the winding device by the clamping force.

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