A Ti-811 alloy bar and a method of manufacturing the same

Abstract

The application discloses a preparation method of Ti-811 alloy rod, which comprises the following steps: ingot smelting; blank forging, wherein: open forging is performed at T β +(100-150) DEG C in a segmented heating mode, open forging is performed after heat preservation; intermediate forging is performed at T β +(50-100) DEG C, elongation is performed by using a multiple full-anvil method after heat preservation; elongation is performed at T β -(20-40) DEG C by using the multiple full-anvil method, the final forging temperature is greater than 900 DEG C, and the total deformation is greater than 60%; blank rolling is performed at T β -(40-60) DEG C, the deformation rate in the rolling process is 2-3 m / s, the final rolling temperature is greater than 850 DEG C, and the single-fire deformation is greater than 40%; radial forging is performed at T β -(15-30) DEG C, the forging speed is 2.5-4 m / min, the single-pass reduction amount is 5-20 mm, and the single-fire deformation is greater than 30%; the rod is straightened, and then air cooling is performed. The preparation method of the Ti-811 alloy rod makes the prepared Ti-811 alloy rod have small and uniform structure, high flaw detection level, good high-temperature creep resistance and obviously improved finished product rate. The application further provides the Ti-811 alloy rod prepared by the method.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, specifically to a Ti-811 alloy rod and its preparation method. Background Technology

[0002] High-temperature titanium alloys are highly attractive materials for aero-engine applications, offering high strength levels from room temperature to 600°C, while having only half the density of steel or nickel-based alloys. Among them, Ti-811 alloy (its nominal chemical composition is Ti-8Al-1Mo-1V) is a near-α type heat-resistant titanium alloy with many advantages such as high room temperature and high-temperature strength, good thermal stability, and high-temperature creep resistance.

[0003] Currently, domestic standards for Ti-811 alloy bars have clear assessment indicators for high-temperature creep performance, with flaw detection using a Φ0.8mm flat-bottomed hole and specifying the level of noise. The main production processes for Ti-811 alloy bars are currently rolling and forging. Forged bars, compared to rolled bars, exhibit smaller differences in transverse and longitudinal microstructure and superior high-temperature tensile and creep properties. However, Ti-811 alloy has a high Al equivalent, poor hot working ability, and the forging deformation process is difficult to control, resulting in significant intangible losses. Therefore, it is difficult to meet the production requirements for small-diameter bars.

[0004] Therefore, it is necessary to develop a Ti-811 alloy bar processing method that meets the requirements of large deformation hot working, ensures the yield of small-sized bars, and meets the requirements of industrial production. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a Ti-811 alloy bar and its preparation method. The process combines free forging, rolling and radial forging to make the prepared Ti-811 alloy bar have a fine and uniform microstructure, high flaw detection level, good high temperature creep resistance and significantly improved yield.

[0006] The first aspect of this invention is to provide a method for preparing Ti-811 alloy rods, comprising the following steps:

[0007] Step S1, Ingot smelting: After adding alloying elements according to the nominal chemical composition Ti-8Al-1Mo-1V, the electrode is pressed and then smelted in a vacuum arc furnace to obtain an ingot.

[0008] Step S2, forging and billet preparation, wherein:

[0009] Forging: in T βSegmented heating is carried out at a temperature of + (100~150)℃, and after heat preservation, the billet is forged. During the billet forging, a multi-upsetting and drawing forging process is adopted to ensure that the original as-cast structure is fully broken. The final forging temperature is >950℃, and the total deformation in the single-phase region is >85%.

[0010] Intermediate forging to prepare rolled billets: at T β Heating at (50~100)℃, and then stretching using the full-anvil method after heat preservation;

[0011] In T β - Heating at (20~40)℃, and after holding at that temperature, multiple full-anvil drawing processes are performed to achieve a final forging temperature >900℃, ensuring a total deformation >60%;

[0012] Step S3, billet rolling: heating temperature T β - (40~60)℃, after the billet is heated, it is rolled into radial forging billet through multiple large deformation rolling processes. The deformation rate in the rolling process is 2~3m / s, the final rolling temperature is >850℃, and the deformation amount per single heat is >40%;

[0013] Step S4, radial forging: heating temperature T β - (15~30)℃, after heating, forge to the finished size, wherein the forging speed is 2.5~4m / min, the diameter reduction per pass is 5~20mm, and the deformation per pass is >30%;

[0014] Step S5: Straighten the bar and then perform air cooling.

[0015] Furthermore, in step S1, the particle size of the sponge titanium raw material for ingot smelting is 2mm~12mm, and the intermediate alloy is added in the form of Al55V, Al60Mo and aluminum briquettes; the voltage during the smelting stabilization stage is 30V~40V, and the current is 10kA~20kA.

[0016] Furthermore, in step S2, during the billet forging process, the original heating temperature is increased by 30~50℃ before the ingot is taken out of the furnace, and the holding time is 30~60min.

[0017] Furthermore, in step S2, when the heating temperature of the intermediate forging billet is above the phase transformation point, the holding time is the billet cross-sectional size × (0.5-0.6) min; when the heating temperature of the intermediate forging billet is below the phase transformation point, the holding time is the billet cross-sectional size × (0.7-0.8) min.

[0018] Furthermore, in step S2, when the total deformation in the two-phase region is >50%, a high-temperature homogenization treatment step is added. The process conditions for the high-temperature homogenization treatment are: heat treatment temperature T. βAfter keeping it at +15~30℃ for 2~4 hours, quickly transfer it to a water tank for cooling. The transfer time should be <30s and the water temperature should be ≤70℃.

[0019] Furthermore, in step S3, the billet ends are chamfered before rolling, and the chamfer is (80~100) mm × (8~10)°.

[0020] Furthermore, in step S4, the length of the bar stock is controlled to be 2500-3000mm when blanking before radial forging.

[0021] The second aspect of the present invention is to provide a Ti-811 alloy rod, which is obtained by the preparation method of the first aspect.

[0022] Compared with the prior art, the Ti-811 alloy rod and its preparation method provided by the present invention have the following advantages:

[0023] The Ti-811 alloy bar preparation method provided by this invention employs a combination of free forging billet preparation, rolling transition, and radial forging forming. First, the free forging process involves multiple full-anvil elongation at high temperature to fully break down the as-cast microstructure and obtain a uniform rolled billet. Then, a high-speed, large-deformation rolling process is introduced, utilizing the high deformation rate and good strain penetration of rolling to further refine the grains, homogenize the microstructure, and significantly improve the surface quality of the billet, providing a high-quality billet for subsequent radial forging. Finally, precision forming is performed through radial forging to further improve and control the microstructure, ensuring a uniform and fine microstructure in the final product. Therefore, the Ti-811 alloy bar preparation method of this invention effectively overcomes the problems of uneven deformation, easy surface cracking, multiple forging passes, and low yield caused by the narrow hot working window and high deformation resistance of Ti-811 alloy in the pure forging route. By optimizing the forging and rolling process parameters and sequentially connecting the three processes, a synergistic effect is achieved, ultimately improving processing efficiency and yield while ensuring high performance indicators.

[0024] II. The method for preparing Ti-811 alloy bars provided by this invention exhibits excellent performance consistency while ensuring high performance indicators. The room temperature tensile strength (Rm) shows a fluctuation range of less than 40 MPa within the same batch of bars, and the creep plastic strain (ε) at 425℃ is also excellent. p The fluctuation range of creep was controlled within 0.05%, and the creep value was generally lower than 0.15%.

[0025] III. The method for preparing Ti-811 alloy bars provided by the present invention introduces a high-speed, large-deformation rolling process, which significantly shortens the hot working cycle and reduces the preparation time of small-sized billets from (5~10) min / piece to (2~3) min / piece, thereby greatly improving the yield. The yield of the present invention can reach more than 50%.

[0026] IV. The Ti-811 alloy bar provided by this invention exhibits a stable ultrasonic noise level between -10dB and -12dB, resulting in a high signal-to-noise ratio. Furthermore, the introduction of the rolling process significantly improves the bar's microstructure, greatly reducing the probability of defects caused by microstructure inhomogeneity and the likelihood of defective products appearing during flaw detection.

[0027] V. The method for preparing Ti-811 alloy bars provided by this invention is generally applicable to the batch and engineering preparation of small-sized forged bars with poor processing plasticity. It can also ensure the microstructure, room temperature and high temperature performance, and flaw detection properties of small-sized bars with high strength and poor processing plasticity. This process can be further promoted. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a microstructure diagram of the Ti-811 alloy Ф25mm bar in Example 1 of this invention;

[0030] Figure 2 This is the flaw detection curve of the Ti-811 alloy Ф25mm specification bar in Example 1 of the present invention;

[0031] Figure 3 This is a microstructure diagram of the Ti-811 alloy Ф40mm bar in Example 2 of this invention;

[0032] Figure 4 This is the flaw detection curve of the Ti-811 alloy Ф40mm specification bar in Example 2 of the present invention;

[0033] Figure 5 This is a microstructure diagram of the Ti-811 alloy Ф32mm bar in Comparative Example 1 of this invention;

[0034] Figure 6 This is the flaw detection curve of the Ti-811 alloy Ф32mm specification bar in Comparative Example 1 of this invention.

[0035] Figure 7 This is a microstructure diagram of the Ti-811 alloy Ф42mm bar in Comparative Example 2 of this invention;

[0036] Figure 8 This is the flaw detection curve of the Ti-811 alloy Ф42mm specification bar in Comparative Example 2 of this invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] Example 1: Preparation of Ti-811 alloy bars with a diameter of Ф25mm

[0040] A method for preparing Ti-811 alloy bars with a diameter of Ф25mm includes the following steps:

[0041] Step S1: Ingot Melting. The raw material for ingot melting, sponge titanium, has a particle size of 2mm~12mm. Intermediate alloys are added in the form of Al55V, Al60Mo, and aluminum briquettes. After thorough and uniform mixing using an automatic mixer, the mixture is pressed into electrodes. The mixing time is >60s. After electrode preparation, the electrodes are melted three times in a vacuum arc remelting furnace to obtain an ingot with a diameter of Ф720mm. The voltage during the stabilization stage of melting is 30V~40V, and the current is 10kA~20kA. The measured phase transition point is 1045℃.

[0042] Step S2: Forging and billet preparation. First forging of billet: Segmented heating at 1150℃ (first, preheat the ingot at ≤800℃, hold for 120 minutes, then raise the temperature to 1150℃ with the furnace and hold for 150 minutes). After holding, forging of billet is carried out. Specifically, after holding and before the ingot is taken out of the furnace, the temperature is raised to 1180℃ and held for 30 minutes for forging of billet. The forging of billet adopts a multi-upsetting and drawing forging process. After two upsetting and drawing deformations, it is laterally drawn into an octagonal prism with a side length of about 400mm. The final forging temperature is >950℃ and the total deformation in the single-phase region is >85%.

[0043] Intermediate forging, stages 2-4: Heating at 1080℃~1100℃, followed by multiple full-anvil forging and drawing forging processes, forging the billet into an octagonal prism with a side length of approximately 220mm through 2 stages; heating at 1020℃, followed by multiple full-anvil forging and drawing forging processes, forging the billet into an octagonal prism with a side length of approximately 170mm. Final forging temperature > 900℃, total deformation > 60%.

[0044] Fifth heat treatment: The billet undergoes homogenization treatment at a temperature ranging from 1060℃ for 2 hours, followed by rapid transfer to a water bath for cooling (transfer time < 30 seconds, water temperature ≤ 70℃). This homogenization process transforms the original two-phase microstructure into a single, fully β-structure at high temperature. Rapid water cooling ensures the precipitated α-structure is fine, further refining the microstructure and improving the overall uniformity of the bar's microstructure.

[0045] 6th-7th heating: Heating at 1020℃, followed by holding at that temperature, and then drawing and forging the billet into a Φ150mm round bar.

[0046] Step S3: Billet Rolling. The forged billet is chamfered at the ends, with chamfer dimensions of (80~100) mm × (8~10)°. After chamfering, it is rolled on a roughing mill. 8th~9th passes: Rolling heating temperature 1000℃. After heating, the billet is rolled on a roughing mill through multiple passes with large deformation to a Φ70mm radial forging billet. Rolling speed 2.3m / s, final rolling temperature >850℃, single-pass deformation >40%.

[0047] Step S4: Radial Forging: After necessary surface treatment, the billet prepared in Step S3 is heated for radial forging. Before radial forging, the blank is cut to a length of approximately 2500mm~3000mm. 10th~11th passes: Heating temperature 1025℃. After heating, the billet is forged to the finished size on a horizontal precision forging machine at a forging speed of 3.3m / min, with a deformation rate >50% per pass.

[0048] Step S5: After the 11th forging, the bar is straightened on a straightening machine using residual heat, and then cooled by air after straightening.

[0049] In this embodiment, the holding time for heating the forging billet above the phase transformation point is the billet cross-sectional size × 0.5 min, and the holding time for heating the forging billet below the phase transformation point is the billet cross-sectional size × 0.8 min.

[0050] The microstructure and flaw detection curves of the Ti-811 alloy Ф25mm bar prepared in this embodiment are shown in the following figures. Figure 1 and Figure 2 As shown in Table 1, the properties of the Ti-811 alloy Ф25mm gauge bars prepared in this embodiment are as follows:

[0051] Table 1: Properties of Ti-811 alloy Ф25mm gauge bars from Example 1

[0052]

[0053] Example 2: Preparation of Ti-811 alloy bars with a diameter of Φ40mm

[0054] A method for preparing Ti-811 alloy bars with a diameter of Φ40mm includes the following steps:

[0055] Step S1: Ingot Melting. The raw material for ingot melting, sponge titanium, has a particle size of 2mm~12mm. Intermediate alloys are added in the form of Al55V, Al60Mo, and aluminum briquettes. After thorough and uniform mixing using an automatic mixer, the mixture is pressed into electrodes. The mixing time is >60s. After electrode preparation, the electrodes are melted three times in a vacuum arc furnace to obtain an ingot with a diameter of Ф720mm. The voltage during the stabilization stage of melting is 30V~40V, and the current is 10kA~20kA. The measured phase transition point is 1042℃.

[0056] Step S2: Forging and billet preparation. First forging of billet: Segmented heating at 1150℃, followed by billet forging after holding. Specifically: After holding and before the ingot is removed from the furnace, the temperature is raised to 1180℃ and held for 30 minutes for billet forging. The billet forging adopts a multi-upsetting and drawing forging process. After two upsetting and drawing deformations, it is laterally drawn into an octagonal prism with a side length of approximately 400mm. The final forging temperature is >950℃, and the total deformation in the single-phase region is >85%.

[0057] Intermediate forging, stages 2-4: Heating at 1080℃~1100℃, followed by multiple full-anvil forging and drawing forgings, forging the billet into an octagonal prism with a side length of approximately 220mm through 2 stages; heating again at 1020℃, followed by multiple full-anvil forging and drawing forgings, forging the billet into an octagonal prism with a side length of approximately 170mm. Final forging temperature > 900℃, total deformation > 60%.

[0058] Fifth heat treatment: Homogenize the billet, heat treatment temperature range 1060℃, hold for 2 hours, then quickly transfer to a water tank for cooling, transfer time <30s, water temperature ≤70℃.

[0059] 6th-7th heating: Heating at 1020℃, followed by holding at that temperature, and then drawing and forging the billet into a Φ150mm round bar.

[0060] Step S3: Billet Rolling. The forging billet is chamfered at the ends, with chamfer dimensions of (80~100) mm × (8~10)°. After chamfering, it is rolled on a roughing mill. 8th~9th passes: Rolling heating temperature 1000℃. After heating, the billet is rolled on the roughing mill through multiple passes with large deformation to a Φ70mm radial forging billet. Rolling speed 2.3m / s, final rolling temperature >850℃, single-pass deformation >40%.

[0061] Step S4: Radial Forging: After necessary surface treatment, the billet prepared in Step 3 is heated for radial forging. Before radial forging, the blank should be cut to a length of approximately 2500mm~3000mm. Tenth Forging: Heating temperature 1020℃. After heating, forging to the finished size on a horizontal precision forging machine at a forging speed of 3.3m / min and a deformation rate >50%.

[0062] Step S5: After forging, the bar is straightened on a straightening machine using residual heat, and then cooled by air after straightening.

[0063] In this embodiment, the holding time for heating the forging billet above the phase transformation point is the billet cross-sectional size × 0.6 min, and the holding time for heating the forging billet below the phase transformation point is the billet cross-sectional size × 0.7 min.

[0064] The microstructure and flaw detection curves of the Ti-811 alloy Ф40mm bar prepared in this embodiment are shown in the following figures. Figure 3 and Figure 4 As shown in Table 2, the properties of the Ti-811 alloy Ф40mm gauge bar prepared in this embodiment are as follows:

[0065] Table 2: Properties of Ti-811 alloy Ф40mm gauge bars from Example 2

[0066]

[0067] Comparative Example 1: Preparation of Ti-811 alloy bars with a diameter of Ф32mm (free forging + radial forging process)

[0068] A method for preparing Ti-811 alloy bars with a diameter of Ф32mm includes the following steps:

[0069] Step S1: Ingot Melting. The raw material for ingot melting, sponge titanium, has a particle size of 2mm~12mm. Intermediate alloys are added in the form of Al55V, Al60Mo, and aluminum briquettes. After thorough and uniform mixing using an automatic mixer, the mixture is pressed into electrodes. The mixing time is >60s. After electrode preparation, the electrodes are melted three times in a vacuum arc furnace to obtain an ingot with a diameter of Ф720mm. The voltage during the stabilization stage of melting is 30V~40V, and the current is 10kA~20kA. The measured phase transition point is 1041℃.

[0070] Step S2: Forging and billet preparation. First forging of billet: Segmented heating at 1150℃, followed by billet forging after holding. Specifically: After holding and before the ingot is removed from the furnace, the temperature is raised to 1180℃ and held for 30 minutes for billet forging. The billet forging adopts a multi-upsetting and drawing forging process. After two upsetting and drawing deformations, it is laterally drawn into an octagonal prism with a side length of approximately 400mm. The final forging temperature is >950℃, and the total deformation in the single-phase region is >85%.

[0071] Intermediate forging, stages 2-4: Heating at 1080℃~1100℃, followed by multiple full-anvil forging and drawing forging processes, forging the billet into an octagonal prism with a side length of approximately 220mm through 2 stages; heating again at 1020℃, followed by multiple full-anvil forging and drawing forging processes, forging the billet into an octagonal prism with a side length of approximately 160mm. Final forging temperature > 900℃, total deformation > 60%.

[0072] Fifth heat treatment: Homogenize the billet, heat treatment temperature range 1060℃, hold for 2 hours, then quickly transfer to a water tank for cooling, transfer time <30s, water temperature ≤70℃.

[0073] 6th-7th heating: Heating at 1020℃, and after holding at that temperature, drawing and forging are performed to forge the billet into a round bar of Φ130mm.

[0074] Step S3: Radial Forging: After necessary surface treatment, the billet prepared in step S2 is heated for radial forging. Before radial forging, the blank is cut to a length of approximately 2500mm~3000mm. 8th~9th forging passes: Heating temperature 1020℃. After heating, the billet is forged to the finished size on a horizontal precision forging machine at a forging speed of 3.3m / min and a deformation rate >50%.

[0075] Step S4: After forging, the bar is straightened on a straightening machine using residual heat, and then cooled by air after straightening.

[0076] In this comparative example, the holding time for heating the forging billet above the phase transformation point is 0.5 min × billet cross-sectional dimension, and the holding time for heating the forging billet below the phase transformation point is 0.8 min × billet cross-sectional dimension. Compared with Example 1 / Example 2, Comparative Example 1 maintains the same parameters except for the absence of a rolling deformation process. The yield of the product produced by this process is approximately 40%.

[0077] The microstructure and flaw detection curves of the Ti-811 alloy Ф32mm bar prepared in this comparative example are shown in the figure below. Figure 5 and Figure 6 As shown in Table 3, the properties of the Ti-811 alloy Ф32mm gauge bars prepared in this comparative example are as follows:

[0078] Table 3: Properties of Ti-811 alloy Ф32mm gauge bars from Comparative Example 1

[0079]

[0080] Comparative Example 2: Preparation of Ti-811 alloy bars with a diameter of Ф42mm (free forging + rolling process)

[0081] A method for preparing Ti-811 alloy bars with a diameter of Φ42mm includes the following steps:

[0082] Step S1: Ingot Melting. The raw material for ingot melting, sponge titanium, has a particle size of 2mm~12mm. Intermediate alloys are added in the form of Al55V, Al60Mo, and aluminum briquettes. After thorough and uniform mixing using an automatic mixer, the mixture is pressed into electrodes. The mixing time is >60s. After electrode preparation, the electrodes are melted three times in a vacuum arc furnace to obtain an ingot with a diameter of Ф720mm. The voltage during the stabilization stage of melting is 30V~40V, and the current is 10kA~20kA. The measured phase transition point is 1043℃.

[0083] Step S2: Forging and billet preparation. First forging of billet: Segmented heating at 1150℃, followed by billet forging after holding. Specifically: After holding and before the ingot is removed from the furnace, the temperature is raised to 1180℃ and held for 30 minutes for billet forging. The billet forging adopts a multi-upsetting and drawing forging process. After two upsetting and drawing deformations, it is laterally drawn into an octagonal prism with a side length of approximately 400mm. The final forging temperature is >950℃, and the total deformation in the single-phase region is >85%.

[0084] Intermediate forging, stages 2-4: Heating at 1080℃~1100℃, followed by multiple full-anvil forging and drawing forging processes, forging the billet into an octagonal prism with a side length of approximately 220mm through 2 stages; heating again at 1020℃, followed by multiple full-anvil forging and drawing forging processes, forging the billet into an octagonal prism with a side length of approximately 160mm. Final forging temperature > 900℃, total deformation > 60%.

[0085] Fifth heat treatment: Homogenize the billet, heat treatment temperature range 1060℃, hold for 2 hours, then quickly transfer to a water tank for cooling, transfer time <30s, water temperature ≤70℃.

[0086] 6th-7th heating: Heating at 1020℃, followed by holding at that temperature, and then drawing and forging the billet into a Φ150mm round bar.

[0087] Step S3: Rolling Forming: After necessary surface treatment, the billet prepared in step S2 is heated and radially rolled. 8th-9th passes: Heating temperature 1000℃, after heating, forging to Φ70mm on a rolling mill at a rolling speed of 2.3m / min, deformation per pass >40%; 9th pass: Heating temperature 1000℃, after heating, forging to Φ45mm on a rolling mill at a rolling speed of 2.0m / min, deformation >45%.

[0088] Step S4: After forging, the bar is straightened on a straightening machine using residual heat, and then cooled by air after straightening.

[0089] In this comparative example, the holding time for heating the forging billet above the phase transformation point is 0.5 min × billet cross-sectional dimension, and the holding time for heating the forging billet below the phase transformation point is 0.8 min × billet cross-sectional dimension. Compared with Example 1 / Example 2, Comparative Example 2 maintains the same parameters except for the absence of a radial forging process and minor adjustments to the rolling speed of the rolling forming heat. The yield of the product produced by this process is approximately 52%.

[0090] The microstructure and flaw detection curves of the Ti-811 alloy Ф42mm bar prepared in this comparative example are shown in the figure below. Figure 7 and Figure 8 As shown in Table 4, the properties of the Ti-811 alloy Ф42mm gauge bars prepared in this comparative example are as follows:

[0091] Table 4: Properties of Ti-811 alloy Ф42mm gauge bars from Comparative Example 2

[0092]

[0093] Based on the three forming processes described in Examples 1 and 2 and Comparative Examples 1 and 2, the three processes show significant differences in terms of core indicators such as bar microstructure, properties, flaw detection, and yield:

[0094] The free forging + rolling billet + radial forging process (Examples 1 and 2) has the best overall performance: the rolling billet process effectively refines the grains, and the radial forging process makes the microstructure uniform and fine, laying the foundation for stable performance. The flaw detection fully meets the process requirements, and the yield reaches about 50%. It takes into account both quality and output stability, and is suitable for scenarios with high requirements for comprehensive performance.

[0095] The free forging + radial forging process (Comparative Example 1) has obvious shortcomings: the rolling billet process is omitted, so it is impossible to further improve the microstructure of the difficult-to-deform alloy, resulting in poor microstructure uniformity, insufficient high-temperature creep performance, and failure to fully meet the flaw detection standards. The yield is only 40%, and it is only suitable for simple working conditions with extremely low requirements for high-temperature performance and flaw detection, and with emphasis on strength and stability.

[0096] The advantage of the free forging + rolling forming process (Comparative Example 2) lies in the quality stability: the microstructure is uniform and fine, the flaw detection is completely qualified, and the yield rate of 52% is slightly higher than other processes. However, the high-temperature strength margin is insufficient, which limits its application in high-temperature and harsh environments. It is more suitable for normal temperature or low-load high-temperature scenarios.

[0097] In summary, the rolling and billet preparation process is crucial for improving the uniformity of the microstructure and the pass rate of flaw detection in TA11 bars; radial forging requires a reasonable billet preparation process to realize its advantages, and enterprises can choose the appropriate process according to the product performance requirements.

[0098] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing Ti-811 alloy rods, characterized in that, Includes the following steps: Step S1, Ingot Melting: After adding alloying elements according to the nominal chemical composition Ti-8Al-1Mo-1V, the electrode is pressed and melted in a vacuum arc furnace to obtain an ingot. Step S2, forging and billet preparation, wherein: Forging: in T β Segmented heating is carried out at a temperature of + (100~150)℃, and after heat preservation, the billet is forged. During the billet forging, a multi-upsetting and drawing forging process is adopted to ensure that the original as-cast structure is fully broken. The final forging temperature is >950℃, and the total deformation in the single-phase region is >85%. Intermediate forging to prepare rolled billets: at T β Heating at +50~100℃, followed by multiple full-anvil stretching operations after heat preservation; at T β - Heating at (20~40)℃, and after holding at that temperature, multiple full-anvil drawing processes are performed to achieve a final forging temperature >900℃, ensuring a total deformation >60%; Step S3, billet rolling: heating temperature T β - (40~60)℃, after the billet is heated, it is rolled into radial forging billet through multiple large deformation rolling processes. The deformation rate in the rolling process is 2~3m / s, the final rolling temperature is >850℃, and the deformation amount per single heat is >40%; Step S4, radial forging: heating temperature T β - (15~30)℃, after heating, forge to the finished size, wherein the forging speed is 2.5~4m / min, the diameter reduction per pass is 5~20mm, and the deformation per pass is >30%; Step S5: Straighten the bar and then perform air cooling.

2. The method for preparing Ti-811 alloy rods according to claim 1, characterized in that, In step S1, the particle size of the sponge titanium raw material for ingot smelting is 2mm~12mm, and the intermediate alloy is added in the form of Al55V, Al60Mo and aluminum granules; the voltage during the smelting stabilization stage is 30V~40V, and the current is 10kA~20kA.

3. The method for preparing Ti-811 alloy rods according to claim 1, characterized in that, In step S2, during the billet forging process, the original heating temperature is increased by 30~50℃ before the ingot is taken out of the furnace, and the holding time is 30~60min.

4. The method for preparing Ti-811 alloy rods according to claim 2, characterized in that, In step S2, when the heating temperature of the intermediate forging billet is above the phase transformation point, the holding time is the billet cross-sectional size × (0.5-0.6) min; when the heating temperature of the intermediate forging billet is below the phase transformation point, the holding time is the billet cross-sectional size × (0.7-0.8) min.

5. The method for preparing Ti-811 alloy rods according to claim 1, characterized in that, In step S2, when the total deformation in the two-phase region is greater than 50%, a high-temperature homogenization treatment step is added. The process conditions for the high-temperature homogenization treatment are: heat treatment temperature is T. β After keeping it at +15~30℃ for 2~4 hours, quickly transfer it to a water tank for cooling. The transfer time should be <30s and the water temperature should be ≤70℃.

6. The method for preparing Ti-811 alloy rods according to claim 1, characterized in that, In step S3, the billet ends are chamfered before rolling, and the chamfer is (80~100) mm × (8~10)°.

7. The method for preparing Ti-811 alloy rods according to claim 1, characterized in that, In step S4, the length of the bar stock is controlled to be 2500-3000mm when blanking before radial forging.

8. A Ti-811 alloy rod, characterized in that, Prepared by the method according to any one of claims 1-7.

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