阅读说明：本技术 大规格无缝深孔盲孔筒体等温超塑成形方法 (Isothermal superplastic forming method for large-size seamless deep-hole blind-hole cylinder ) 是由 徐斌 王立荣 李哲 周翔宇 洪凌翔 周建华 吴瑞恒 于 2021-08-09 设计创作，主要内容包括：一种大规格无缝深孔盲孔筒体等温超塑成形方法,以钛合金棒材为原材料,将钛合金棒材加热至锻造温度并保温后,置于与锻造温度相同并保温后的通用平模进行超塑性等温制钛合金圆饼坯料；将钛合金圆饼坯料加热至锻造温度并保温后,置于与锻造温度相同并保温后的预锻模具内进行等温超塑盲孔预制坯成形,出模冷却,获得钛合金盲孔预锻坯；将钛合金盲孔预锻坯加热至等温成形温度并保温后,置于与等温成形温度相同并保温后的无缝深孔盲孔筒体成形终锻模具进行等温成形；对钛合金大规格无缝深孔盲孔筒体进行热处理,获得钛合金大规格无缝深孔盲孔筒体。本发明工序少、重量轻、强度高、性能好、制造成本低、材料利用率高、机加工量小、成本低、组织均匀。(An isothermal superplastic forming method for a large-size seamless deep-hole blind-hole cylinder comprises the steps of taking a titanium alloy bar as a raw material, heating the titanium alloy bar to a forging temperature, preserving heat, and placing the titanium alloy bar in a general flat die which is the same as the forging temperature and is preserved heat to carry out superplastic isothermal production of a titanium alloy round cake blank; heating the titanium alloy round cake blank to a forging temperature and preserving heat, placing the titanium alloy round cake blank in a pre-forging die which is the same as the forging temperature and preserves heat for isothermal superplastic blind hole preform forming, demolding and cooling to obtain a titanium alloy blind hole pre-forging blank; heating the titanium alloy blind hole pre-forging blank to isothermal forming temperature, preserving heat, and then placing the titanium alloy blind hole pre-forging blank in a seamless deep hole blind hole cylinder forming finish forging die which is the same as the isothermal forming temperature and is preserved heat for isothermal forming; and carrying out heat treatment on the large-specification seamless deep-hole blind-hole barrel of the titanium alloy to obtain the large-specification seamless deep-hole blind-hole barrel of the titanium alloy. The invention has the advantages of less working procedures, light weight, high strength, good performance, low manufacturing cost, high material utilization rate, small machining amount, low cost and uniform structure.)

1. An isothermal superplastic forming method for a large-size seamless deep-hole blind-hole cylinder is characterized by comprising the following steps:

1) a step of superplastic isothermal blank making on a hot working forming device:

a) heating a titanium alloy bar in a resistance furnace, wherein the heating temperature H1 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, the Tbeta is the phase transition temperature of the titanium alloy, the heat preservation time T1 (minutes) is (0.6-0.8) multiplied by D1 (mm), and D1 is the diameter of a titanium alloy bar blank;

b) the mould is connected with hot-working forming equipment;

c) heating the die at a temperature H ═ Tbeta- (30-50) DEG C, wherein Tbeta is the phase transition temperature of the titanium alloy, and keeping the temperature of the die for 30-60 minutes after the temperature of the die is raised;

d) placing the titanium alloy bar obtained in the steps a) and c) and a mould on the mould by using an operating machine, carrying out superplastic isothermal blank making on the titanium alloy bar to obtain a titanium alloy round cake blank, and carrying out air cooling after forging;

e) turning and processing a titanium alloy round cake blank, and detecting a flaw;

2) a step of isothermal superplastic forming of preforms on a hot forming apparatus:

a) heating the titanium alloy round cake blank in the step 1) in a box type resistance furnace, wherein the heating temperature H2 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, and the heat preservation time T2 (min) is (0.6-0.8) multiplied by D1 (mm);

b) connecting the seamless deep hole blind hole cylinder pre-forging die with hot-working forming equipment;

c) heating the die at a temperature H ═ Tbeta- (30-50) DEG C, wherein Tbeta is the phase transition temperature of the titanium alloy, and keeping the temperature of the die for 30-60 minutes after the temperature of the die is raised;

d) placing the titanium alloy round cake blank obtained in the steps a) and c) and the blind hole cylinder pre-forging die in a pre-forging die by using an operating machine to perform isothermal superplastic preform forming, and performing air cooling after forging to obtain a titanium alloy preform;

3) the isothermal superplastic forming method of the titanium alloy blind hole cylinder on hot-working forming equipment comprises the following steps:

a) heating the titanium alloy preform obtained in the step 2) in a box-type resistance furnace, wherein the heating temperature H2 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, and the heat preservation time T2 (min) is (0.6-0.8) multiplied by D1 (mm);

b) connecting a blind hole cylinder forming finish forging die with hot working forming equipment;

c) heating the die at a temperature H ═ Tbeta- (30-50) DEG C, wherein Tbeta is the phase transition temperature of the titanium alloy, and keeping the temperature of the die for 30-60 minutes after the temperature of the die is raised;

d) placing the titanium alloy prefabricated blank obtained in the steps a) and c) and the blind hole cylinder forming finish forging die in a blind hole cylinder forming finish forging die by using an operating machine to perform isothermal superplastic forming on the titanium alloy blind hole cylinder, and performing air cooling after forging;

e) and (3) carrying out heat treatment on the titanium alloy large-size seamless deep-hole blind-hole cylinder to obtain the titanium alloy large-size seamless deep-hole blind-hole cylinder.

2. The isothermal superplastic forming method of large-size seamless deep-hole blind-hole cylinder bodies according to claim 1, characterized in that: in the step 1), heating the titanium alloy bar to the forging temperature, preserving heat, and then placing the titanium alloy bar in a general flat die which is the same as the forging temperature and preserves heat to perform superplastic isothermal production of a titanium alloy round cake blank.

3. The isothermal superplastic forming method of large-size seamless deep-hole blind-hole cylinder bodies according to claim 1, characterized in that: in the step 2), heating the titanium alloy round cake blank to the forging temperature, preserving heat, placing the blank in a pre-forging die which is the same as the forging temperature and preserved heat for isothermal superplastic blind hole preform forming, demolding and cooling to obtain the titanium alloy blind hole pre-forged blank.

4. The isothermal superplastic forming method of large-size seamless deep-hole blind-hole cylinder bodies according to claim 1, characterized in that: in the step 3), the titanium alloy blind hole pre-forging blank is heated to isothermal forming temperature and is subjected to heat preservation, and then the titanium alloy blind hole pre-forging blank is placed in a seamless deep hole blind hole barrel forming finish forging die which is the same as the isothermal forming temperature and is subjected to heat preservation for isothermal forming.

The technical field is as follows:

the invention belongs to the field of metallurgy, relates to a hot working technology of a titanium alloy material, and particularly relates to an isothermal superplastic forming method of a large-size seamless deep-hole blind-hole cylinder.

Background art:

titanium alloys have high strength, low density and are widely used in the aerospace industry. In particular to a titanium alloy integral deep hole blind hole cylinder which has high strength and good comprehensive performance.

Titanium alloys can be classified into three types, alpha alloys, (alpha + beta) alloys and beta alloys, according to the composition of the phases, and China is respectively represented by TA, TC and TB.

The alpha alloy contains a certain amount of elements for stabilizing alpha phase, and mainly consists of alpha phase in an equilibrium state. The alpha alloy has small specific gravity, good heat strength, good weldability and excellent corrosion resistance.

② the (alpha + beta) alloy contains a certain amount of elements for stabilizing alpha phase and beta phase, and the structure of the alloy in equilibrium state is alpha phase and beta phase. The (alpha + beta) alloy has moderate strength and can be heat-treated to strengthen.

Beta alloy contains a large amount of elements for stabilizing beta phase, and can completely keep the high-temperature beta phase to room temperature. Beta alloys are commonly used as high strength, high toughness materials.

However, the titanium alloy has poor formability and is sensitive to the change of forming process parameters, and the change of forming temperature, deformation speed and even cooling speed can cause the obvious change of the structure and performance of the titanium alloy, so that the production of the large-size seamless deep hole blind hole cylinder made of the titanium alloy is almost impossible for the conventional free forging and common die forging of the titanium alloy.

The prior process for producing the titanium alloy large-size seamless deep-hole blind-hole cylinder mainly comprises two processes:

firstly, the 'rough forging + machining' type titanium alloy seamless deep hole blind hole cylinder process (one of the processes)

1. Titanium alloy shallow hole rough forging blank cylinder is formed by adopting titanium alloy free forging and common die forging;

2. machining and drilling a deep hole;

3. and (4) machining and forming.

The process has the advantages that: the tool and the die are low in investment cost, and the tool and the die have the advantages of a single sample piece without considering product performance and structure and a shorter titanium alloy blind hole cylinder.

The disadvantages are that: the process is multiple, the machining amount is large, the material loss is large, and the performance and the structure can not be ensured. The titanium alloy large-size seamless deep-hole blind-hole cylinder with the length of more than 1 meter cannot be produced by the process.

Secondly, the second process (second process) of the mechanically-added titanium alloy seamless deep hole blind hole cylinder

1. Determining a titanium alloy bar according to the outer diameter and the length of the cylinder;

2. machining and drilling a deep hole;

3. and (4) machining and forming.

The process has the advantages that: the process is simple, and the titanium alloy large-size seamless deep-hole blind-hole cylinder is directly produced by a titanium alloy bar through a machining deep-hole drilling and machining forming process.

The disadvantages are that: the material loss is large, the machining amount is large, and the cost is high; the production period is long, and batch production cannot be carried out; the structure and the performance of the cylinder body depend on the original structure and the performance of the material, and the requirement of the aerospace industry cannot be met, particularly the large-size blind hole cylinder body.

The invention content is as follows:

aiming at the technical problems in the prior art, the invention provides an isothermal superplastic forming method for a large-specification seamless deep-hole blind-hole cylinder, and the isothermal superplastic forming method for the large-specification seamless deep-hole blind-hole cylinder aims to solve the technical problem that the large-specification seamless deep-hole blind-hole cylinder is difficult to prepare in the prior art.

The invention provides an isothermal superplastic forming method for a large-size seamless deep-hole blind-hole cylinder, which comprises the following steps of:

1) a step of superplastic isothermal blank making on a hot working forming device:

a) heating a titanium alloy bar in a resistance furnace, wherein the heating temperature H1 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, the Tbeta is the phase transition temperature of the titanium alloy, the heat preservation time T1 (minutes) is (0.6-0.8) multiplied by D1 (mm), and D1 is the diameter of a titanium alloy bar blank;

b) the mould is connected with hot-working forming equipment;

c) heating the die at a temperature H ═ Tbeta- (30-50) DEG C, wherein Tbeta is the phase transition temperature of the titanium alloy, and keeping the temperature of the die for 30-60 minutes after the temperature of the die is raised;

d) placing the titanium alloy bar obtained in the steps a) and c) and a mould on the mould by using an operating machine, carrying out superplastic isothermal blank making on the titanium alloy bar to obtain a titanium alloy round cake blank, and carrying out air cooling after forging;

e) turning and processing a titanium alloy round cake blank, and detecting a flaw;

2) a step of isothermal superplastic forming of preforms on a hot forming apparatus:

a) heating the titanium alloy round cake blank in the step 1) in a box type resistance furnace, wherein the heating temperature H2 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, and the heat preservation time T2 (min) is (0.6-0.8) multiplied by D1 (mm);

b) connecting the seamless deep hole blind hole cylinder pre-forging die with hot-working forming equipment;

c) heating the die at a temperature H ═ Tbeta- (30-50) DEG C, wherein Tbeta is the phase transition temperature of the titanium alloy, and keeping the temperature of the die for 30-60 minutes after the temperature of the die is raised;

d) placing the titanium alloy round cake blank obtained in the steps a) and c) and the blind hole cylinder pre-forging die in a pre-forging die by using an operating machine to perform isothermal superplastic preform forming, and performing air cooling after forging to obtain a titanium alloy preform;

3) the isothermal superplastic forming method of the titanium alloy blind hole cylinder on hot-working forming equipment comprises the following steps:

a) heating the titanium alloy preform obtained in the step 2) in a box-type resistance furnace, wherein the heating temperature H2 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, and the heat preservation time T2 (min) is (0.6-0.8) multiplied by D1 (mm);

b) connecting a blind hole cylinder forming finish forging die with hot working forming equipment;

c) heating the die at a temperature H ═ Tbeta- (30-50) DEG C, wherein Tbeta is the phase transition temperature of the titanium alloy, and keeping the temperature of the die for 30-60 minutes after the temperature of the die is raised;

d) placing the titanium alloy prefabricated blank obtained in the steps a) and c) and the blind hole cylinder forming finish forging die in a blind hole cylinder forming finish forging die by using an operating machine to perform isothermal superplastic forming on the titanium alloy blind hole cylinder, and performing air cooling after forging;

e) and (3) carrying out heat treatment on the titanium alloy large-size seamless deep-hole blind-hole cylinder to obtain the titanium alloy large-size seamless deep-hole blind-hole cylinder.

The invention is the technical progress of the prior art (the 'rough forging plus machining' titanium alloy large-size seamless deep-hole blind-hole cylinder process and the 'machining' titanium alloy large-size seamless deep-hole blind-hole cylinder process), and the prepared titanium alloy large-size seamless deep-hole blind-hole cylinder product has the advantages of high quality performance, complex shape, no residual stress, high material utilization rate and the like, and meets the application requirements of special users.

The method comprises the steps of taking a titanium alloy bar as a raw material, heating the titanium alloy bar to a forging temperature, preserving heat, and placing the titanium alloy bar in a general flat die which is the same as the forging temperature and is preserved heat to carry out superplastic isothermal production of a titanium alloy round cake blank; heating the titanium alloy round cake blank to a forging temperature and preserving heat, placing the titanium alloy round cake blank in a pre-forging die which is the same as the forging temperature and preserves heat for isothermal superplastic blind hole preform forming, demolding and cooling to obtain a titanium alloy blind hole pre-forging blank; heating the titanium alloy blind hole pre-forging blank to isothermal forming temperature, preserving heat, and then placing the titanium alloy blind hole pre-forging blank in a seamless deep hole blind hole cylinder forming finish forging die which is the same as the isothermal forming temperature and is preserved heat for isothermal forming; and carrying out heat treatment on the large-specification seamless deep-hole blind-hole barrel of the titanium alloy to obtain the large-specification seamless deep-hole blind-hole barrel of the titanium alloy. The method has the advantages of less procedures, light weight, high strength, good performance, low manufacturing cost, high material utilization rate, small machining amount, low cost, uniform structure and no residual stress, and can realize batch production.

Compared with the prior art, the invention has the following advantages:

1. compared with the existing 'rough forging and machining' process for the titanium alloy large-specification seamless deep-hole blind-hole cylinder, the titanium alloy large-specification seamless deep-hole blind-hole cylinder prepared by the method has the advantages of few working procedures, light weight, high strength, good performance, low manufacturing cost and the like.

2. Compared with the existing 'machining type' titanium alloy seamless deep hole cylinder process, the titanium alloy large-size seamless deep hole blind hole cylinder prepared by the method has the advantages of high material utilization rate, small machining amount, low cost, capability of realizing batch production and high organization and performance.

3. The production of the isothermal superplastic titanium alloy large-size seamless deep-hole blind-hole cylinder can be realized;

4. the material utilization rate is high, and the titanium alloy is a relatively expensive material, so that the manufacturing cost is reduced;

5. the machining amount is reduced, the machining cost is reduced, and batch production can be realized;

6. has high quality, homogeneous structure, complicated shape and no residual stress.

Description of the drawings:

FIG. 1 is a process flow diagram of the isothermal superplastic forming method of a large-size seamless deep-hole blind-hole cylinder.

FIG. 2 is a structural diagram of a large-size seamless deep-hole blind-hole cylinder prepared by the method of the invention.

The specific implementation mode is as follows:

EXAMPLE 1 preparation of titanium alloy Large-sized seamless deep-hole blind-hole Cylinder before thermoforming

1. Preparing raw materials:

1.1, the raw material is titanium alloy bar produced by adopting a conventional process.

1.2, blanking of bars: the dimension G1 is G (1.1-1.3), the height-diameter ratio H1/D1 is 2.2-2.8, G1, H1 and D1 are the weight (kilogram), height (millimeter) and diameter (millimeter) of the titanium alloy bar blank, and G is the weight (kilogram) of the titanium alloy integral deep-hole blind-hole cylinder.

1.3, the surface quality of the bar blank is required to have no visible cracks and folding defects.

2. Hot-forming equipment:

the energy X (unit, ton) of a conventional press, such as an oil press, is related to the orthographic projection area S (unit, square millimeter) of the deformed part of the titanium alloy large-size seamless deep-hole blind hole cylinder body and the deformation-resistant stress F (unit, kilogram/square millimeter) of a material (conventional): p is larger than SF, and the deformation stress resistance F of the titanium alloy material is 8-12 kg/square millimeter under the condition of isothermal superplastic forming. (P is the pressure of the press in kilograms).

3. Preparing a mould:

2 types of dies are designed conventionally, namely a seamless deep hole blind hole barrel pre-forging die and a seamless deep hole blind hole barrel forming finish-forging die.

Example 2 thermoforming of titanium alloy Large-Scale seamless deep-hole Blind Cylinder

1. Superplastic isothermal blank making on a hot working forming device:

1.1, adopting a superplastic isothermal forging process to superplastically and isothermally blank a titanium alloy bar into a titanium alloy round cake blank (a pierced billet).

And 1.2, heating the titanium alloy bar in a resistance furnace, wherein the heating temperature H1 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, the Tbeta is the phase transition temperature of the titanium alloy, the heat preservation time T1 (minutes) is (0.6-0.8) multiplied by D1 (millimeters), and D1 is the diameter of the titanium alloy bar blank.

1.3, connecting the die (general flat die) with a hot-working forming device (oil press).

And 1.4, heating the die (a general flat die), wherein the heating temperature H is Tbeta- (30-50) DEG C, and the Tbeta is the phase transition temperature of the titanium alloy. And (5) keeping the temperature of the mold for 30-60 minutes after the mold is heated to the temperature.

And 1.5, putting the obtained titanium alloy bar and a die (a general flat die) on the die by using an operating machine, performing superplastic isothermal blank making to obtain a titanium alloy round cake blank, and performing air cooling after forging.

1.6, turning and detecting the flaw of the titanium alloy round cake blank (rough blank).

2. Isothermal superplastic forming of preforms on a hot forming apparatus:

2.1, adopting an isothermal superplastic forming process for the prefabricated blank.

2.2, heating a titanium alloy round cake blank (rough blank) in a box type resistance furnace, wherein the heating temperature H2 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, and the heat preservation time T2 (minutes) is (0.6-0.8) multiplied by D1 (mm).

2.3, connecting the seamless deep-hole blind-hole cylinder pre-forging die with hot-forming equipment (an oil press).

And 2.4, heating the die, wherein the heating temperature H is Tbeta- (30-50) DEG C, and the Tbeta is the phase transition temperature of the titanium alloy. And (5) keeping the temperature of the mold for 30-60 minutes after the mold is heated to the temperature.

2.5, putting the obtained titanium alloy round cake blank (rough blank) and the blind hole cylinder pre-forging die into a pre-forging die by using an operating machine to perform isothermal superplastic pre-forming blank forming, and cooling in air after forging.

2.6, size and shape according to design drawings.

3. Carrying out isothermal superplastic forming on the titanium alloy blind hole cylinder on hot-working forming equipment:

3.1, adopting an isothermal superplastic forming process of the titanium alloy blind hole cylinder.

And 3.2, heating the titanium alloy preform in a box type resistance furnace, wherein the heating temperature H2 (alpha + beta titanium alloy) is Tbeta- (30-50) DEG C, and the holding time T2 (minutes) is (0.6-0.8) multiplied by D1 (mm).

3.3, connecting the blind hole cylinder forming finish forging die with hot working forming equipment (an oil press).

And 3.4, heating the die, wherein the heating temperature H is Tbeta- (30-50) DEG C, and the Tbeta is the phase transition temperature of the titanium alloy. And (5) keeping the temperature of the mold for 30-60 minutes after the mold is heated to the temperature.

3.5, putting the titanium alloy prefabricated blank and the blind hole cylinder forming finish forging die into a blind hole cylinder forming finish forging die by using an operating machine to perform isothermal superplastic forming on the titanium alloy blind hole cylinder, and cooling in air after forging.

3.6, size and shape according to design drawings.

Example 3 Heat treatment of titanium alloy Large-sized seamless deep-hole Blind Cylinder

According to different titanium alloy material grades, different performance and structure requirements, different heat treatment systems are adopted for the seamless deep-hole blind-hole cylinder forged piece.

Example 4

By implementing the method, a TC4 titanium alloy seamless deep-hole blind-hole cylinder product with the phi of 342mm multiplied by the phi of 310mm multiplied by 1210mm is produced by utilizing a 2000-ton oil press, a blind-hole cylinder pre-forging die and a blind-hole cylinder forming die, and the application requirements of special purposes are met.

The production process is shown in figure 1:

step 1, preparation of a raw material (titanium alloy bar material): blanking the titanium alloy bar blank according to the design weight and the height-to-width ratio H1/D1 of 2.2-2.8. The blanking size phi is 240mm multiplied by 610 mm; and (5) inspecting the size and the surface quality, wherein the surface quality is required to be free of cracks and folding defects visible to naked eyes.

Step 2, superplastic isothermal blank making: and (3) superplastic isothermal blank making of the titanium alloy bar into a titanium alloy forged blank (a pierced billet) by adopting an isothermal superplastic forming process. The rod was heated in a resistance furnace at a temperature H1 of 950 ℃ (T β of 984 ℃) for a holding time T1 (min) of 160 min.

And 3, carrying out isothermal superplastic preform forming on a 2000-ton oil press: the isothermal superplastic preform forming process is adopted, a titanium alloy forging blank (blank) is heated in a box-type resistance furnace to a forging temperature and is kept warm for a certain time, and then the titanium alloy forging blank is placed in a blank-making forming die which is the same as the forging temperature and is kept warm for a certain time to carry out isothermal superplastic preform forming. Titanium alloy round cake blank (crude billet) H2 ═ 950 ℃ (T beta ═ 984 ℃), and the heat preservation time T2 (minutes) ═ 160 minutes. Heating the die at 950 ℃, keeping the temperature for 1 hour, and cooling in air after forging. The size and shape are according to the design drawing.

And 4, carrying out isothermal superplastic forming on a 2000-ton oil press: the isothermal superplastic forming process is adopted, the titanium alloy prefabricated blank is heated in a box-type resistance furnace to the forging temperature and is kept warm for a certain time, and then the titanium alloy prefabricated blank is placed in a blank-making forming die which is the same as the forging temperature and is kept warm for a certain time to carry out isothermal superplastic prefabricated blank forming. The heating temperature H3 of the titanium alloy preform is 950 ℃ (T beta 984 ℃), and the holding time T3 (minutes) is 160 minutes. Heating the die at 950 ℃, keeping the temperature for 1 hour, and cooling in air after forging. The size and shape are according to the design drawing.

And 5, adopting a heat treatment system for the TC4 titanium alloy seamless deep-hole blind-hole cylinder forging:

air cooling at 700 deg.C for 1 hr

The high-quality titanium alloy large-size seamless deep-hole blind-hole cylinder product prepared by the method has the characteristics of light weight, high strength and excellent product performance, and the performance and the structure are as follows: the structure is equiaxed (see fig. 2 below for details), and the chamber tensile strength σ b is 940 Mpa. The dimension is phi 342mm phi 310mm 1210mm, and the application requirement of products with special purposes can be met.