A short process forging method of Ti1100 alloy

Abstract

The present application relates to a short process forging method of Ti1100 alloy bar, which is used to solve at least one of the problems of long time, low production efficiency, poor mechanical properties, poor process stability, poor consistency of different batches, high cost and the like in the prior art forging method. The forging method controls the heating times of blooming forging and trans-phase zone forging, and cooperates with gradient air cooling treatment. Specifically, in the organization control, the conventional multi-heating-time beta phase zone upsetting and drawing forging is abandoned, the single-heating-time beta phase zone precise temperature control and dynamic deformation regulation are adopted, the excessive growth of beta grains is avoided, and the needle-like alpha phase lamellar aggregation or equiaxed alpha phase abnormal precipitation is prevented by combining with gradient air cooling, so as to ensure the uniformity of the organization, solve the problems of mechanical property fluctuation exceeding the index and low service reliability.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy technology, and in particular to a short-process forging method for Ti1100 alloy bars. Background Technology

[0002] In the aerospace industry, aero-engines, as core power units, directly determine the flight efficiency, reliability, and safety of aircraft. Hot-section components of engines (such as turbine blades and combustion chambers) operate under extreme conditions of high temperature, high pressure, and high corrosion, placing extremely high demands on the high-temperature strength, creep resistance, and thermal stability of the materials used. Against this backdrop, high-temperature titanium alloys, with their excellent comprehensive mechanical properties and lightweight advantages, have become key materials for manufacturing hot-section components of aero-engines. Among them, Ti1100 alloy, exhibiting superior high-temperature load-bearing capacity and creep resistance within the 600-650℃ temperature range, is widely used in the production of these core components, playing an irreplaceable role in improving the overall performance of aero-engines.

[0003] For Ti1100 alloy, the microstructure is the core factor determining its final mechanical properties. To meet the stringent requirements of high strength and creep resistance for hot-end components of aero-engines, Ti1100 alloy needs to form a specific microstructure, requiring a uniform distribution of acicular α phases on a transformed β matrix. The formation mechanism of this microstructure is as follows: the transformed β matrix provides the alloy with good toughness and plasticity, while the uniformly dispersed acicular α phase can significantly improve the alloy's high-temperature strength and creep resistance through dislocation strengthening and dispersion strengthening. The synergistic effect of these two factors ensures the long-term stable operation of components under extreme service conditions, avoiding the risk of component failure due to insufficient material properties. However, the current forging process system for Ti1100 alloy still faces multiple technical challenges, making it difficult to stably achieve the above-mentioned target microstructure and properties, which has become a key bottleneck restricting the high-quality mass production of hot-end components for aero-engines.

[0004] In terms of microstructure control, conventional multi-heat upsetting forging of the β-phase region has significant defects: First, repeated high-temperature heating easily leads to excessive growth of β grains, destroying the grain refinement effect; second, acicular α phases are prone to agglomeration in lamellar form or precipitation of equiaxed α phases, disrupting microstructure uniformity and ultimately causing mechanical property fluctuations exceeding specifications, reducing service reliability. From an efficiency and cost perspective, multi-heat forging is a lengthy process requiring repeated heating and deformation, significantly increasing energy consumption and costs, extending the production cycle per batch, resulting in low efficiency and difficulty in meeting the large-scale mass production requirements of key aerospace components. Regarding process stability, existing cooling technologies mostly rely on air cooling, which easily leads to uneven precipitation of acicular α phases; moreover, the air cooling effect is greatly affected by weather factors such as temperature, humidity, and wind speed, resulting in significant differences in the cooling rate of the alloy surface, causing poor process stability and difficulty in ensuring batch-to-batch performance consistency, severely restricting the large-scale application of Ti1100 alloy.

[0005] From the perspective of production efficiency and manufacturing cost, the lengthy process of multi-heat β-phase region upsetting and forging also brings many problems. This process requires multiple operations in a cycle of "heating-deformation-cooling-reheating," which not only prolongs the production cycle of a single batch (which usually takes several days or even weeks), resulting in low production efficiency and making it difficult to meet the aerospace industry's demand for large-scale and rapid mass production of core components; at the same time, the repeated heating process consumes a lot of electrical and thermal energy, significantly increasing energy costs. In addition, the multi-heat operation requires more equipment resources and labor costs, further increasing the manufacturing cost of Ti1100 alloy components, which contradicts the aerospace industry's cost control requirements. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a short-process forging method for Ti1100 alloy bars, in order to solve at least one of the problems of existing forging methods, such as long forging time, low production efficiency, poor mechanical properties, poor process stability, poor performance consistency between different batches, and high cost.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A short-process forging method for Ti1100 alloy bars includes the following steps:

[0009] S1: Forging: The Ti1100 ingot is forged sequentially above the β phase transformation point, below the β phase transformation point, and above the β phase transformation point.

[0010] S2: Transphase region forging: Upsetting and drawing forging in one pass above the β phase transformation point;

[0011] S3: Radial forging: Upsetting and drawing forging is performed once above the β phase transformation point to obtain Ti1100 bar stock;

[0012] The process includes, after the billet forging step, the cross-phase forging step, and the radial forging step, gradient air cooling of the billet. The gradient air cooling is performed by first placing the billet in a first temperature range for furnace cooling, then transferring it to a second temperature range for furnace cooling, and finally air cooling. The first temperature range is greater than the second temperature range.

[0013] Furthermore, in S1, upsetting and drawing forging are performed at 50~150℃ above the β phase transformation point, upsetting and drawing forging are performed at 20~30℃ below the β phase transformation point, and upsetting and drawing forging are performed at 20~50℃ above the β phase transformation point.

[0014] Furthermore, the temperature is maintained at 50-150°C above the β phase transition point for 120-200 minutes.

[0015] Furthermore, the upsetting and drawing forging process at a β phase transformation point of 50~150℃ or above includes multiple upsetting and drawing processes, with each deformation amount being 40~55%.

[0016] Furthermore, the single-stage upsetting and drawing forging at 20-30°C below the β phase transformation point includes controlling the deformation to 35-50% for one upsetting and one drawing.

[0017] Furthermore, in S1, at 20~50℃ above the β phase transformation point, the deformation is controlled at 45~55% and diagonal upsetting and drawing are performed to make the octagonal shape parallel to a height of 180~200mm.

[0018] Furthermore, in S2, the gradient air cooling after the billet forging step involves first furnace cooling at 550-650℃ for 30-45 minutes, then furnace cooling at 300-400℃ for 60-80 minutes, and finally air cooling.

[0019] Furthermore, in S3, the gradient air cooling after the transphase forging step involves first furnace cooling at 450-550℃ for 30-45 minutes, followed by furnace cooling at 200-300℃ for 60-80 minutes, and finally air cooling. Similarly, the gradient air cooling after the radial forging step involves first furnace cooling at 250-350℃ for 30-45 minutes, followed by furnace cooling at 150-250℃ for 60-80 minutes, and finally air cooling.

[0020] Furthermore, S3 also includes heat treatment and machining after gradient air cooling; preferably, the heat treatment is to hold at 700~850℃ for 60~80 minutes.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The forging method of the present invention controls the number of forging passes in the initial forging and cross-phase region forging, and coordinates with gradient air cooling treatment. Specifically, in terms of microstructure control, it abandons the conventional multi-pass β phase region upsetting and drawing forging, and avoids excessive growth of β grains by precise temperature control and dynamic deformation regulation in the β phase region in a single pass. At the same time, combined with gradient air cooling, it prevents the agglomeration of needle-like α phase sheets or abnormal precipitation of equiaxed α phase, ensuring microstructure uniformity and solving the problems of excessive mechanical property fluctuations and low service reliability.

[0023] 2. In terms of efficiency and cost, single-fire β-phase forging significantly shortens the process, reduces repeated heating and deformation, lowers energy consumption, shortens the production cycle of a single batch, improves efficiency, and meets the needs of large-scale mass production of key aerospace components. In terms of process stability, gradient air cooling replaces air cooling, eliminating the influence of weather factors such as temperature, humidity, and wind speed, stably controlling the cooling rate, ensuring uniform precipitation of needle-like α-phase, improving process stability and batch-to-batch performance consistency, effectively overcoming the shortcomings of existing technologies, and realizing the short-process preparation of highly uniform Ti1100 alloy bars with good comprehensive performance.

[0024] 3. By controlling parameters such as temperature, time, and deformation in different steps, this invention ensures the excellent mechanical properties and uniform microstructure of Ti1100 bars.

[0025] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1 Metallographic image of the edge position of the bar obtained in Embodiment 1 of the present invention;

[0028] Figure 2 This is a metallographic image of the bar obtained in Example 1 of the present invention at position D / 4.

[0029] Figure 3 This is a metallographic image of the bar obtained in Embodiment 1 of the present invention at position D / 2. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0031] A specific embodiment of the present invention discloses a short-process forging method for Ti1100 alloy bars, comprising the following steps:

[0032] S1: Forging: The Ti1100 ingot is forged sequentially above the β phase transformation point, below the β phase transformation point, and above the β phase transformation point.

[0033] S2: Transphase region forging: Upsetting and drawing forging in one pass above the β phase transformation point;

[0034] S3: Radial forging: Upsetting and drawing forging is performed once above the β phase transformation point to obtain Ti1100 bar stock;

[0035] The process includes, after the billet forging step, the cross-phase forging step, and the radial forging step, gradient air cooling of the billet. The gradient air cooling is performed by first placing the billet in a first temperature range for furnace cooling, then transferring it to a second temperature range for furnace cooling, and finally air cooling. The first temperature range is greater than the second temperature range.

[0036] Compared with existing technologies, the forging method of this invention controls the number of forging passes in the initial forging and cross-phase region forging, and coordinates with gradient air cooling treatment. Specifically, in terms of microstructure control, it abandons the conventional multi-pass β-phase region upsetting and drawing forging, and avoids excessive growth of β grains by precise temperature control and dynamic deformation regulation in the β-phase region during a single pass. At the same time, combined with gradient air cooling, it prevents the agglomeration of needle-like α-phase sheets or abnormal precipitation of equiaxed α-phase, ensuring microstructure uniformity and solving the problems of excessive mechanical property fluctuations and low service reliability.

[0037] In addition, in terms of efficiency and cost, single-fire β-phase region forging significantly shortens the process, reduces repeated heating and deformation, lowers energy consumption, shortens the production cycle of a single batch, improves efficiency, and meets the needs of large-scale mass production of key aerospace components. In terms of process stability, gradient air cooling replaces air cooling, eliminating the influence of weather factors such as temperature, humidity, and wind speed, stably controlling the cooling rate, ensuring uniform precipitation of needle-like α phase, improving process stability and batch-to-batch performance consistency, effectively overcoming the shortcomings of existing technologies, and realizing the short-process preparation of highly uniform Ti1100 alloy bars with good comprehensive performance.

[0038] Specifically, in S1, the elemental composition of the Ti1100 ingot, by mass percentage, includes Al: 5.60~6.40%; Sn: 2.40~3.00%; Zr: 3.50~4.50%; Mo: 0.35~0.50%; Si: 0.35~0.50%, with the balance being Ti.

[0039] Specifically, in S2, the diameter of the ingot is 200-250mm, for example, 200mm, 210mm, 220mm, 230mm, 240mm, or 250mm.

[0040] Specifically, in S1, upsetting and drawing forging is performed at 50~150℃ above the β phase transformation point, upsetting and drawing forging is performed at 20~30℃ below the β phase transformation point (e.g., 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃), and upsetting and drawing forging is performed at 20~50℃ above the β phase transformation point (e.g., 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, 50℃).

[0041] It should be noted that the temperature range of 50-150℃ above the β phase transformation point is because the alloy is in a cast state at this temperature, with coarse grains and poor plastic deformation ability. High temperatures are used to improve the alloy's plasticity and deformation capacity, while reducing its deformation resistance. Below 50℃ above the phase transformation point, the temperature approaches the α+β two-phase region, where plasticity decreases and deformation becomes uneven. Above 150℃ above the phase transformation point, excessive growth of β grains occurs, making subsequent refining through processing or heat treatment difficult, thus affecting the material's final strength and toughness.

[0042] The second step, upsetting and forging at 20-30°C below the β phase transformation point, aims to obtain a strong and tough balanced α+β dual-phase microstructure, balancing microstructure refinement and forming stability. At temperatures above 20°C below the phase transformation point, the forging process will approach or even enter the single-phase β region, ultimately failing to achieve the desired microstructure refinement and making it difficult to form the ideal strong and tough dual-phase microstructure. At temperatures below 30°C below the phase transformation point, the α phase proportion is too high and the hardness increases, leading to a sharp rise in deformation resistance and making defects such as microstructure tearing and surface cracks more likely during forging.

[0043] The third step involves upsetting and forging at 20–50°C above the β phase transformation point. The aim is to refine the microstructure of the preceding two-phase deformation and eliminate defects. Below 20°C above the phase transformation point, the temperature approaches the two-phase region, resulting in insufficient β-phase content and difficulty in achieving sufficient recrystallization, leading to poor microstructure refinement. Above 50°C, excessive β-grain growth occurs, forming coarse transformed microstructure upon cooling, reducing the material's final strength and plasticity. The narrow range of 20–50°C achieves microstructure optimization while avoiding the adverse effects of high temperatures on microstructure stability, balancing refinement effectiveness with process controllability.

[0044] Preferably, in S1, the temperature is first maintained at 50~150℃ above the β phase transition point, for example, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, for 120~200min, for example, 120min, 130min, 140min, 150min, 160min, 170min, 180min, 190min, 200min.

[0045] Specifically, in S1, the upsetting and drawing forging process performed at a β phase transformation point of 50~150℃ (e.g., 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃) includes multiple upsetting and drawing processes, with each deformation amount being 40~55%, for example, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 55%.

[0046] Preferably, the deformation is first controlled at 40-50% (e.g., 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%) for one upsetting and one drawing, and then the deformation is controlled at 45-55% (e.g., 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%) for one upsetting and one drawing.

[0047] Specifically, in S1, the single-fire upsetting and drawing forging at 20-30°C below the β phase transformation point (e.g., 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C) includes controlling the deformation amount to 35-50% (e.g., 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%) for one upsetting and one drawing.

[0048] Specifically, at 20~50℃ above the β phase transition point, for example, 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, and 50℃, control the deformation amount to 45~55% (for example, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, and 55%), perform diagonal upsetting and pulling, and beveling the octagon to a parallel height of 180~200mm (for example, 180mm, 185mm, 190mm, 195mm, and 200mm).

[0049] Specifically, the gradient air cooling after the billet forging step involves first furnace cooling at 550-650℃ (e.g., 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃) for 30-45 minutes (e.g., 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min). (43 min, 44 min, 45 min), then furnace cooled at 300-400℃ (e.g., 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃) for 60-80 min (e.g., 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 78 min, 80 min), and finally air cooled.

[0050] Specifically, in S2, the temperature above the β phase transition point is 20~50℃ above the β phase transition point, for example, 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, and 50℃, and the temperature is maintained for 80~200min, for example, 80min, 100min, 120min, 140min, 160min, 180min, and 200min.

[0051] It should be noted that industrial forging of titanium alloys is all done under natural conditions. The forging process is actually cooling forging. The temperature at the beginning of forging is above the phase transformation point, and the temperature at the end of forging is below the phase transformation point, which easily forms a fine lath structure. This structure has excellent high-temperature load-bearing capacity and creep resistance. The temperature range of 20-50℃ is set to ensure that the forging start temperature is above the phase transformation point.

[0052] Specifically, in S2, the upsetting and drawing forging includes one upsetting and one drawing with a deformation controlled at 35-45% (e.g., 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%), and one diagonal upsetting and one drawing with a deformation controlled at 35-45% (e.g., 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%), followed by reflow in the furnace for 30-40 minutes (e.g., 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min). (in), controlling the deformation amount to 35-45% (e.g., 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%), perform one upsetting and one drawing; controlling the deformation amount to 35-45% (e.g., 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%), perform one diagonal upsetting and one drawing, beveling to an octagonal shape until a parallel height of 180-190mm (e.g., 180mm, 181mm, 182mm, 183mm, 184mm, 185mm, 186mm, 187mm, 188mm, 189mm, 190mm), and drawing to length. 100~120×L mm. Where L is the length after forging.

[0053] Specifically, the gradient air cooling after the forging step in the transphase region involves furnace cooling at 450-550℃ (e.g., 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃) for 30-45 minutes (e.g., 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min). (43 min, 44 min, 45 min), then furnace cooled at 200-300℃ (e.g. 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃) for 60-80 min (e.g. 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 78 min, 80 min), and finally air cooled.

[0054] Specifically, in S3, the temperature above the β phase transition point is 20~30℃ above the β phase transition point (e.g., 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃), and the temperature is maintained for 50~90min (e.g., 50min, 55min, 60min, 65min, 70min, 75min, 80min, 85min, 90min).

[0055] It should be noted that the reason for setting the forging temperature at 20°C above the phase transformation point is the same as explained in step S2. Compared with the S2 temperature, its upper limit is reduced from 50°C to 30°C. The reason for reducing the temperature is to control the final microstructure and avoid excessive growth of β grains. After cooling, the α phase precipitates coarsely, forming Widmanstätten and lath structures.

[0056] Specifically, the gradient air cooling after the radial forging step involves first furnace cooling at 250-350℃ (e.g., 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃) for 30-45 minutes (e.g., 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min). (43 min, 44 min, 45 min), then furnace cooled at 150-250℃ (e.g., 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃) for 60-80 min (e.g., 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 78 min, 80 min), and finally air cooled.

[0057] Specifically, S3 also includes heat treatment and machining after gradient air cooling.

[0058] Preferably, the heat treatment is performed at 700~850℃ (e.g., 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃) for 60~80min (e.g., 60min, 62min, 64min, 66min, 68min, 70min, 72min, 74min, 76min, 78min, 80min).

[0059] It should be noted that the temperature range of 700-850℃ is the homogenization heat treatment range, which can promote the homogenization of the alloy microstructure. If the temperature is too low, small grains will have difficulty growing, resulting in a bimodal distribution with large grains. If the temperature is too high, the grains will merge and grow, resulting in an overly coarse microstructure.

[0060] Specifically, the diameter of the Ti1100 alloy rod is 40~60mm, for example, 40mm, 42mm, 44mm, 46mm, 48mm, 50mm, 52mm, 54mm, 56mm, 58mm, 60mm.

[0061] In this invention, by controlling parameters such as temperature, time, and deformation in different steps, the excellent mechanical properties and uniform microstructure of Ti1100 bars are ensured.

[0062] The technical solution of the present invention will be further explained below with reference to specific embodiments.

[0063] Example 1

[0064] Preparation in this embodiment The chemical composition of the 43mm Ti1100 bar and Ti1100 ingot, by mass percentage, is as follows: Al: 6.00%; Sn: 2.70%; Zr: 4.00%; Mo: 0.42%; Si: 0.42%, with the balance being Ti. The ingot contains... 200mm Ti1100 ingot, a Ti1100 ingot with uniform composition and no obvious segregation obtained through three VAR melting processes.

[0065] The short-process forging method for Ti1100 alloy bars in this embodiment includes the following steps:

[0066] S1: Forging: Hold Ti1100 ingot at 150℃ above the β phase transformation point for 150 min, control the deformation to 40% and perform conventional upsetting and drawing → control the deformation to 45% and perform upsetting and drawing again → after surface shaping, return to the furnace for reheating at a temperature 20℃ below the β phase transformation point → control the deformation to 38% and perform conventional upsetting and drawing again → after surface shaping, return to the furnace for reheating at a temperature 50℃ above the β phase transformation point, control the deformation to 45% and perform diagonal upsetting and drawing again → turn into an octagon until the parallel height is 180mm → cool in a 600℃ furnace for 30 min → cool in a 350℃ furnace for 60 min, and finally air cool → full grinding;

[0067] S2: Transphase zone forging: Heat the furnace to 30°C above the β phase transformation point and hold for 150 min → Control the deformation amount to 40% and perform conventional upsetting and drawing → Control the deformation amount to 45% and perform diagonal upsetting and drawing → Return to the furnace for 30 min → Control the deformation amount to 40% and perform conventional upsetting and drawing → Control the deformation amount to 45% and perform diagonal upsetting and drawing → Turn the octagon to a parallel height of 180 mm → Draw to φ120×L mm → Place in a 500°C furnace and cool for 30 min → Place in a 250°C furnace and cool for 60 min, then transfer to air cooling → Final heat treatment and full grinding;

[0068] S3: Radial forging: Heat the furnace to 30°C above the β phase transformation point and hold for 60 minutes → radial forging to φ47×L mm → cool in a 300°C furnace for 30 minutes → cool in a 200°C furnace for 60 minutes and then air cool.

[0069] S4: Heat treatment: Heat the empty furnace to 750℃, hold for 60 minutes, air cool, and adjust the residual heat.

[0070] S5: Machining to finished bar stock.

[0071] Example 2

[0072] The same bar stock and ingot were prepared in this embodiment as in Example 1, and the specific forging method is as follows:

[0073] S1: Forging: Hold Ti1100 ingot at 50°C above the β phase transformation point for 200 min, control deformation to 45% and perform conventional upsetting and drawing → control deformation to 50% and perform upsetting and drawing again → after surface shaping, return to the furnace for reheating at a temperature 25°C below the β phase transformation point → control deformation to 35% and perform conventional upsetting and drawing again → after surface shaping, return to the furnace for reheating at a temperature 20°C above the β phase transformation point, control deformation to 50% and perform diagonal upsetting and drawing again → turn into an octagon until the parallel height is 190 mm → cool in a 650°C furnace for 40 min → cool in a 400°C furnace for 70 min, and finally air cool → full grinding;

[0074] S2: Transphase zone forging: Heat the furnace to 20°C above the β phase transformation point and hold for 200 min → Control the deformation amount to 35% and perform conventional upsetting and drawing → Control the deformation amount to 35% and perform diagonal upsetting and drawing → Return to the furnace for 35 min → Control the deformation amount to 35% and perform conventional upsetting and drawing → Control the deformation amount to 35% and perform diagonal upsetting and drawing → Turn the octagon to a parallel height of 185 mm → Draw to φ110×L mm → Place in a 550°C furnace and cool for 40 min → Place in a 300°C furnace and cool for 70 min, then transfer to air cooling → Final heat treatment and full grinding;

[0075] S3: Radial forging: Heat the furnace to 20°C above the β phase transformation point and hold for 90 minutes → radial forging to φ40×L mm → cool in a 350°C furnace for 40 minutes → cool in a 250°C furnace for 70 minutes and then air cool.

[0076] S4: Heat treatment: Heat the empty furnace to 700℃, hold for 80 minutes, air cool, and adjust the residual heat.

[0077] S5: Machining to finished bar stock.

[0078] Example 3

[0079] The same bar stock and ingot were prepared in this embodiment as in Example 1, and the specific forging method is as follows:

[0080] S1: Forging: Hold Ti1100 ingot at 100℃ above the β phase transformation point for 120 min, control deformation to 50% and perform conventional upsetting and drawing → control deformation to 55% and perform upsetting and drawing again → after surface shaping, return to the furnace for reheating at a temperature 30℃ below the β phase transformation point → control deformation to 50% and perform conventional upsetting and drawing again → after surface shaping, return to the furnace for reheating at a temperature 35℃ above the β phase transformation point, control deformation to 47% and perform diagonal upsetting and drawing again → turn into an octagon until the parallel height is 200mm → cool in a 550℃ furnace for 45 min → cool in a 300℃ furnace for 80 min, and finally air cool → full grinding;

[0081] S2: Transphase zone forging: Heat the furnace to 50°C above the β phase transformation point and hold for 80 minutes → Control the deformation amount to 45% and perform conventional upsetting and drawing → Control the deformation amount to 40% and perform diagonal upsetting and drawing → Return to the furnace for 40 minutes → Control the deformation amount to 45% and perform conventional upsetting and drawing → Control the deformation amount to 40% and perform diagonal upsetting and drawing → Turn the octagon to a parallel height of 190 mm → Draw to φ100×L mm → Place in a 450°C furnace and cool for 45 minutes → Place in a 200°C furnace and cool for 80 minutes, then transfer to air cooling → Final heat treatment and full grinding;

[0082] S3: Radial forging: Heat the furnace to 25°C above the β phase transformation point and hold for 90 min → radial forging to φ60×L mm → cool in a 250°C furnace for 45 min → cool in a 150°C furnace for 80 min and then air cool.

[0083] S4: Heat treatment: Heat the empty furnace to 850℃, hold for 70 minutes, air cool, and adjust the residual heat.

[0084] S5: Machining to finished bar stock.

[0085] Comparative Example 1

[0086] The Ti1100 bar and forging method in this comparative example are similar to those in Example 1. The difference is that in S1, the process of cooling in a 600°C furnace for 30 minutes, cooling in a 350°C furnace for 60 minutes, and finally switching to air cooling is replaced by air cooling only.

[0087] Comparative Example 2

[0088] The Ti1100 bar stock and forging method in this comparative example are similar to those in Example 1. The difference is that in S2, instead of cooling in a 500°C furnace for 30 minutes, then cooling in a 250°C furnace for 60 minutes, and finally air cooling, only air cooling is used.

[0089] Comparative Example 3

[0090] The Ti1100 bar and forging method in this comparative example are similar to those in Example 1. The difference is that in S3, the process of cooling in a 300°C furnace for 30 minutes, then cooling in a 200°C furnace for 60 minutes, and finally air cooling is replaced with air cooling only.

[0091] Comparative Example 4

[0092] The Ti1100 bar and forging method in this comparative example are similar to those in Example 1. The difference is that in S1, the process of cooling in a 600°C furnace for 30 min and then in a 350°C furnace for 60 min followed by air cooling is replaced by cooling at 350°C for 90 min followed by air cooling.

[0093] Comparative Example 5

[0094] The Ti1100 bar and forging method in this comparative example are similar to those in Example 1. The difference is that in S2, instead of cooling in a 500°C furnace for 30 minutes and then in a 250°C furnace for 60 minutes and then air cooling, the process is changed to cooling in a 500°C furnace for 90 minutes and then air cooling.

[0095] Comparative Example 6

[0096] The Ti1100 bar stock and forging method in this comparative example are similar to those in Example 1. The difference is that in S1, the steps of returning the bar to the furnace at a temperature 20°C below the β phase transformation point, controlling the deformation amount to 38% for conventional upsetting and drawing, and then returning it to the furnace for reheating after surface shaping are removed. That is, the upsetting and drawing forging is first performed at a temperature 150°C above the β phase transformation point, and then the upsetting and drawing forging is performed at a temperature 50°C above the β phase transformation point.

[0097] Experimental Example 1

[0098] Mechanical properties and metallographic structures of φ43mm Ti1100 bars prepared in the examples and comparative examples were tested. The results are shown in Table 1. The sampling locations were the edge, D / 4 position, and D / 2 position of the bar.

[0099] Table 1

[0100]

[0101] according to Figure 1It is known that the bar obtained by the forging method of the present invention has a tensile strength ≥1093MPa, preferably 1093-1163MPa, a yield strength ≥1044MPa, preferably 974~1093MPa, an elongation ≥12%, preferably 12~13%, a reduction of area of ​​20~23%, and a batch-to-batch consistency CV≤3%.

[0102] Metallographic images of samples taken from different locations of the bar obtained in Example 1 are shown below. Figure 1-3 As shown. Figure 1 Sampling is performed at the edge location. Figure 2 Sampling at position D / 4 Figure 3 Sampling was performed at position D / 2. As can be seen from the figure, the tissue samples from different locations are uniform and similar, indicating good homogeneity.

[0103] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A short-process forging method for Ti1100 alloy bars, characterized in that, Includes the following steps: S1: Forging: The Ti1100 ingot is forged sequentially above the β phase transformation point, below the β phase transformation point, and above the β phase transformation point. S2: Transphase region forging: Upsetting and drawing forging in one pass above the β phase transformation point; S3: Radial forging: Upsetting and drawing forging is performed once above the β phase transformation point to obtain Ti1100 bar stock; The process includes, after the billet forging step, the cross-phase forging step, and the radial forging step, gradient air cooling of the billet. The gradient air cooling is performed by first placing the billet in a first temperature range for furnace cooling, then transferring it to a second temperature range for furnace cooling, and finally air cooling. The first temperature range is greater than the second temperature range.

2. The short-process forging method for Ti1100 alloy bars according to claim 1, characterized in that, In S1, upsetting and drawing forging is performed once at a temperature of 50~150℃ above the β phase transformation point, once at a temperature of 20~30℃ below the β phase transformation point, and once at a temperature of 20~50℃ above the β phase transformation point.

3. The short-process forging method for Ti1100 alloy bars according to claim 2, characterized in that, Hold at 50-150℃ above the β phase transition point for 120-200 minutes.

4. The short-process forging method for Ti1100 alloy bars according to claim 3, characterized in that, The upsetting and drawing forging process at 50-150°C above the β phase transformation point includes multiple upsetting and drawing processes, with each deformation amount being 40-55%.

5. The short-process forging method for Ti1100 alloy bars according to claim 2, characterized in that, The upsetting and drawing forging process, which involves one heat treatment at 20-30°C below the β phase transformation point, includes controlling the deformation to 35-50% and performing one upsetting and one drawing.

6. The short-process forging method for Ti1100 alloy bars according to claim 2, characterized in that, At 20~50℃ above the β phase transformation point, control the deformation to 45~55% and perform diagonal upsetting and drawing, turning the octagon to a parallel height of 180~200mm.

7. The short-process forging method for Ti1100 alloy bars according to claim 1, characterized in that, In S1, the gradient air cooling after the billet forging step involves first furnace cooling at 550-650℃ for 30-45 minutes, then furnace cooling at 300-400℃ for 60-80 minutes, and finally air cooling.

8. The short-process forging method for Ti1100 alloy bars according to claim 1, characterized in that, In S2, the gradient air cooling after the cross-phase forging step involves first furnace cooling at 450-550℃ for 30-45 minutes, then furnace cooling at 200-300℃ for 60-80 minutes, and finally air cooling.

9. The short-process forging method for Ti1100 alloy bars according to claim 1, characterized in that, In S3, the gradient air cooling after the radial forging step involves first furnace cooling at 250-350℃ for 30-45 minutes, then furnace cooling at 150-250℃ for 60-80 minutes, and finally air cooling.

10. A short-process forging method for Ti1100 alloy bars according to any one of claims 1-9, characterized in that, S3 also includes heat treatment and machining after gradient air cooling.

11. The short-process forging method for Ti1100 alloy bars according to claim 10, characterized in that, The heat treatment is performed at 700~850℃ for 60~80 minutes.

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