A method for preparing a high-temperature titanium alloy forging for aerospace structural parts

Abstract

The application belongs to the technical field of titanium alloy material processing, and relates to a preparation method of a high-temperature titanium alloy forge piece for aerospace structural parts. The titanium alloy forge piece capable of being applied below 650 DEG C is obtained through a combined process of vacuum self-consumption arc furnace smelting, free forging, die forging and heat treatment. The application adds conventional Al, Si, Mo and Zr elements (common and low-cost alloy elements are adopted) to improve the interstitial elements in the alloy. The titanium alloy forge piece capable of being applied at a maximum temperature of 650 DEG C is obtained through the combined process of vacuum self-consumption arc furnace smelting, free forging, die forging and heat treatment. The tensile strength of the forge piece can reach 530 MPa at 650 DEG C, and the residual deformation is less than or equal to 2% under a stress of 300 MPa at the temperature.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy material processing technology, and relates to a method for preparing high-temperature titanium alloy forgings for aerospace structural components. Background Technology

[0002] As spacecraft operate at increasingly higher speeds, the temperature requirements for the entire structural components also increase. Simultaneously, there is a need for weight reduction. While traditional high-temperature alloys can meet the temperature requirements, they cannot meet the weight requirements of the spacecraft. Therefore, much hope is placed on titanium alloys, but traditional titanium alloys generally have a maximum operating temperature of around 500℃.

[0003] Currently, China is also developing some titanium alloys suitable for use at around 600℃. However, these generally involve adding small amounts of rare earth elements such as W and Nb. Due to their high melting points, these elements are prone to forming inclusions and segregation during the smelting process. Obtaining materials with uniform composition places higher demands on the alloy preparation process. Furthermore, the addition of a significant amount of rare earth elements also increases the cost of the material. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing high-temperature titanium alloy forgings for aerospace structural components.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The preparation method of this high-temperature titanium alloy forging for aerospace structural components uses a combination process of "vacuum self-consuming electric arc furnace melting + free forging + die forging + heat treatment" to obtain titanium alloy forgings suitable for temperatures below 650℃.

[0007] Furthermore, the titanium alloy forging has a tensile strength of up to 530 MPa at a temperature of 650°C.

[0008] Furthermore, the residual deformation of the titanium alloy forging is ≤2% at a temperature of 650℃ and a stress of 300MPa.

[0009] Furthermore, the method specifically includes the following steps:

[0010] S1. First, select the ingot raw materials; then, use three vacuum self-consuming arc melting processes to obtain an ingot with uniform composition and no metallurgical defects; finally, process and sample the ingot to complete the detection of the chemical composition of the ingot.

[0011] S2. Ingot blanking: After heating the ingot to 100-200°C above the β phase transformation temperature, blanking is carried out. The total deformation of the blank after blanking and forging is ≥80%.

[0012] S3, Intermediate forging I: The billet is heated to 10-40°C below the β phase transformation temperature and forged 2-4 times, with a single forging deformation of ≥50%;

[0013] S4, β-forging modified forging: The billet is heated to 20°C above the β phase transformation temperature and forged in one pass, with a deformation amount of ≥80% in one pass;

[0014] S5, Intermediate forging II: The billet is heated to 20-40°C below the β phase transformation temperature and forged 2-4 times, with a single forging deformation of ≥50%;

[0015] S6. Heat the billet to 20-40°C below the β phase transformation temperature and shape it to the required specifications;

[0016] S7. According to the requirements of the forging, cut the billet to the required size and then machine it.

[0017] S8. Perform ultrasonic testing on the billet;

[0018] S9. Heat the billet to 20-40°C below the β phase transformation temperature, and place it in the corresponding mold to forge to the required forging size;

[0019] S10. Perform solution treatment and aging on the forgings to complete the preparation of high-temperature titanium alloy forgings.

[0020] Furthermore, S1 specifically includes:

[0021] S1.1 Select sponge titanium, AlMo master alloy, TiSi master alloy, sponge zirconium, and titanium dioxide, and formulate them according to the following composition range;

[0022] Content range 6.2～8 0.4～0.6 3.2～5.0 1.5～3.5 0.18～0.25

[0023] S1.2. Three-stage vacuum self-consuming arc melting is adopted to obtain ingots with uniform composition and no metallurgical defects.

[0024] S1.3 After removing surface defects from the ingot, cut off the ingot riser;

[0025] S1.4. Samples were taken from the head, middle and tail of the ingot to test the chemical composition of the ingot.

[0026] Furthermore, in S10,

[0027] The process parameters for solution treatment are: holding at 50–80°C below the β phase change temperature for 60–150 min, and using oil cooling or water cooling as the refrigeration method;

[0028] The process parameters for aging treatment are: holding at 500℃~600℃ for 240~480min, and air cooling is used for refrigeration.

[0029] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0030] This invention improves the interstitial element content of the alloy by adding conventional Al, Si, Mo, and Zr elements (using relatively common and low-cost alloying elements). Through a combined process of "vacuum arc furnace melting + free forging + die forging + heat treatment", titanium alloy forgings that can be used up to 650°C are obtained. The tensile strength of the forgings at 650°C can reach 530MPa, while the residual deformation is ≤2% under 300MPa stress at this temperature. Attached Figure Description

[0031] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of a high-temperature titanium alloy forging for aerospace structural components provided in Embodiment 1 of the present invention. Detailed Implementation

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods consistent with some aspects of the invention as detailed in the appended claims.

[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, wherein "□" represents a square billet;

[0036] Example 1

[0037] See Figure 1 As shown in the figure, this embodiment provides a method for preparing high-temperature titanium alloy forgings for aerospace structural components, specifically including the following steps:

[0038] 1) Ingot batching

[0039] Raw materials such as sponge titanium, AlMo master alloy, TiSi master alloy, sponge zirconium, and titanium dioxide are selected and formulated according to the following composition range;

[0040]

[0041]

[0042] 2) Ingot smelting

[0043] The ingots are produced by three vacuum self-consumption melting processes to obtain φ450mm ingots with uniform composition and no metallurgical defects.

[0044] 3) Ingot processing and sampling

[0045] After removing surface defects from the ingot, the riser of the ingot is cut off, and samples are taken from the head, middle and tail of the ingot respectively.

[0046] 4) Chemical composition testing of ingots

[0047] head 6.05 0.35 3.11 1.45 0.185 Central 6.08 0.37 3.05 1.56 0.180 tail 5.97 0.32 3.14 1.40 0.185

[0048] 5) Ingot blanking, wherein the phase transformation point of the ingot is 1020℃

[0049] First firing: The ingot is heated to 1150℃ for forging, and the forging deformation is as follows: The total deformation is 110%;

[0050] 6) Intermediate fire secondary forging I

[0051] Second firing: The billet is heated to 1010℃, □400 upsetting → □500 drawing → □400, the deformation amount per firing is 72%;

[0052] Third firing: The billet is heated to 980℃, □400 upsetting → □500 drawing → □400, and the deformation amount per firing is 72%;

[0053] 7) β-Forging Modified Forging

[0054] Fourth firing: The billet is heated to 1040℃, □400 upsetting → □500 drawing → □400 upsetting → □500 drawing → □400, with a deformation of 144% per firing.

[0055] 8) Intermediate fire secondary forging II

[0056] Fifth firing: The billet is heated to 1010℃, □400 upsetting → □500 drawing → □400, with a deformation of 72% per firing;

[0057] Sixth firing: The billet is heated to 980℃, □400 upsetting → □500 drawing → □250, with a deformation of 111% per firing;

[0058] 9) Blank forming

[0059] Seventh heating cycle: Heat the billet to 980℃, then roll it into a φ250 round shape;

[0060] 10) Billet processing

[0061] A φ250 blank with a loading and unloading length of 350mm is then processed to φ240×340.

[0062] 11) Billet Inspection

[0063] The billet was subjected to ultrasonic testing in accordance with the Class A requirements of GB / T5193-2007;

[0064] 12) Forging of forgings

[0065] Heat the billet to 980℃ and place it in a mold to forge the support forging dimensions;

[0066] 13) Heat treatment of forgings

[0067] Solution treatment: Hold at 940℃ for 60 minutes, then cool with oil;

[0068] Aging treatment: Hold at 500℃ for 240 minutes, then air cool;

[0069] 14) Forging processing

[0070] Machining the forgings to the required finished dimensions;

[0071] 15) Mechanical property testing of forgings: Samples were cut from the forgings at the specified sampling locations for mechanical property testing. The test results are shown in Table 1 below:

[0072]

[0073] Example 2

[0074] This embodiment provides a method for preparing high-temperature titanium alloy forgings for aerospace structural components, specifically including the following steps:

[0075] 1) Ingot batching

[0076] Raw materials such as sponge titanium, AlMo master alloy, TiSi master alloy, sponge zirconium, and titanium dioxide are selected and formulated according to the following composition range;

[0077] Content range 8.0 0.6 5.0 3.5 0.205

[0078] 2) Ingot smelting

[0079] The ingot is produced by three vacuum self-consumption melting processes to obtain a φ450mm ingot with uniform composition and no metallurgical defects.

[0080] 3) Ingot processing and sampling

[0081] After removing surface defects from the ingot, the riser of the ingot is cut off, and samples are taken from the head, middle and tail of the ingot respectively.

[0082] 4) Chemical composition testing of ingots

[0083]

[0084]

[0085] 5) Ingot blanking, wherein the phase transformation point of the ingot is 1045℃;

[0086] First firing: The ingot is heated to 1200℃ for forging. The forging deformation of the blank is: φ450 upsetting → φ500 drawing → □400 upsetting → □500 drawing → □400, with a total deformation of 110%.

[0087] 6) Intermediate fire secondary forging I

[0088] Second firing: The billet is heated to 1035℃, □400 upsetting → □500 drawing → □400, and the deformation amount in a single firing is 72%;

[0089] Third firing: The billet is heated to 1005℃, □400 upsetting → □500 drawing → □400, and the deformation amount per firing is 72%;

[0090] 7) β-Forging Modified Forging

[0091] Fourth firing: The billet is heated to 1065℃, □400 upsetting → □500 drawing → □400 upsetting → □500 drawing → □400, the deformation amount per firing is 144%;

[0092] 8) Intermediate fire secondary forging II

[0093] Fifth firing: The billet is heated to 1035℃, □400 upsetting → □500 drawing → □400, and the deformation in a single firing is 72%;

[0094] Sixth firing: The billet is heated to 1005℃, □400 upsetting → □500 drawing → □250, and the deformation amount per firing is 111%;

[0095] 9) Blank forming

[0096] Seventh heating cycle: Heat the billet to 1005℃, then roll it into a 250mm diameter round.

[0097] 10) Billet processing

[0098] A φ250 billet with a loading and unloading length of 350mm is machined to φ240×340.

[0099] 11) Billet Inspection

[0100] The billet was subjected to ultrasonic testing in accordance with the Class A requirements of GB / T5193-2007;

[0101] 12) Forging of forgings

[0102] Heat the billet to 1005℃ and place it in a mold to forge the support forging dimensions;

[0103] 13) Heat treatment of forgings

[0104] Solution treatment: Hold at 995℃ for 60 minutes, then water cool;

[0105] Aging treatment: Hold at 500℃ for 240 minutes, then air cool;

[0106] 14) Forging processing

[0107] Machining the forgings to the required finished dimensions;

[0108] 15) Mechanical property testing of forgings: Samples were cut from the forgings at the specified sampling locations for mechanical property testing. The test results are shown in Table 2 below:

[0109]

[0110] Example 3

[0111] This embodiment provides a method for preparing high-temperature titanium alloy forgings for aerospace structural components, specifically including the following steps:

[0112] 1) Ingot batching

[0113] Raw materials such as sponge titanium, AlMo master alloy, TiSi master alloy, sponge zirconium, and titanium dioxide are selected and formulated according to the following composition range;

[0114] Content range 7.5 0.5 4.0 2.5 0.18

[0115] 2) Ingot smelting

[0116] The ingot is produced by three vacuum self-consumption melting processes to obtain a φ450mm ingot with uniform composition and no metallurgical defects.

[0117] 3) Ingot processing and sampling

[0118] After removing surface defects from the ingot, the riser of the ingot is cut off, and samples are taken from the head, middle and tail of the ingot respectively.

[0119] 4) Chemical composition testing of ingots

[0120] head 7.44 0.44 3.92 2.51 0.210 Central 7.30 0.40 3.88 2.44 0.200 tail 7.49 0.49 3.94 2.46 0.205

[0121] 5) Ingot blanking, wherein the phase transformation point of the ingot is 1045℃;

[0122] First firing: The ingot is heated to 1150℃ for forging. The forging deformation of the blank is: φ450 upsetting → φ500 drawing → □400 upsetting → □500 drawing → □400, with a total deformation of 110%.

[0123] 6) Intermediate fire secondary forging I

[0124] Second firing: The billet is heated to 1035℃, □400 upsetting → □500 drawing → □400, and the deformation amount in a single firing is 72%;

[0125] Third firing: The billet is heated to 1025℃, □400 upsetting → □500 drawing → □400, and the deformation amount per firing is 72%;

[0126] Fourth firing: The billet is heated to 1015℃, □400 upsetting → □500 drawing → □400, and the deformation amount per firing is 72%;

[0127] Fifth firing: The billet is heated to 1005℃, □400 upsetting → □500 drawing → □400, and the deformation in a single firing is 72%;

[0128] 7) β-Forging Modified Forging

[0129] The sixth firing cycle: The billet is heated to 1065℃, □400 upsetting → □500 drawing → □400 upsetting → □500 drawing → □400, and the deformation amount per firing cycle is 144%;

[0130] 8) Intermediate fire secondary forging II

[0131] Seventh firing: The billet is heated to 1035℃, □400 upsetting → □500 drawing → □400, and the deformation amount per firing is 72%;

[0132] Eighth firing: The billet is heated to 1005℃, □400 upsetting → □500 drawing → □250, and the deformation amount per firing is 111%;

[0133] Ninth firing: The billet is heated to 1035℃, □400 upsetting → □500 drawing → □400, and the deformation amount per firing is 72%;

[0134] Tenth firing: The billet is heated to 1005℃, □400 upsetting → □500 drawing → □250, the deformation amount per firing is 111%;

[0135] 9) Blank forming

[0136] Eleventh heating cycle: Heat the billet to 1005℃, then roll it into a φ250 round shape;

[0137] 10) Billet processing

[0138] φ250 billet, 350mm billet for loading and unloading, billet is machined to φ240×340;

[0139] 11) Billet Inspection

[0140] The billet was subjected to ultrasonic testing in accordance with the Class A requirements of GB / T5193-2007;

[0141] 12) Forging of forgings

[0142] The billet is heated to 1005℃ and placed in a mold to forge the support forging.

[0143] 13) Heat treatment of forgings

[0144] Solution treatment: Hold at 990℃ for 60 minutes, then water cool;

[0145] Aging treatment: Hold at 600℃ for 240 minutes, then air cool;

[0146] 14) Forging processing

[0147] Machining the forgings to the required finished dimensions;

[0148] 15) Mechanical property testing of forgings: Samples were cut from the forgings at the specified sampling locations for mechanical property testing. The test results are shown in Table 3 below:

[0149]

[0150] In summary, the method for preparing high-temperature titanium alloy forgings for aerospace structural components provided by this invention uses relatively common and low-cost alloying elements. By using different element ratios, high-low-high-low forging methods, and solution aging heat treatment methods, high-temperature titanium alloy forgings that can be used at temperatures up to 650°C can be obtained.

[0151] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0152] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing high-temperature titanium alloy forgings for aerospace structural components, characterized in that, Titanium alloy forgings suitable for temperatures below 650℃ are obtained through a combined process of "vacuum self-consuming electric arc furnace melting + free forging + die forging + heat treatment". The preparation method specifically includes the following steps: S1. First, select the ingot raw materials; then, use three vacuum self-consuming arc melting processes to obtain an ingot with uniform composition and no metallurgical defects; finally, process and sample the ingot to complete the detection of the chemical composition of the ingot. S1 specifically includes: S1.1 Select sponge titanium, AlMo master alloy, TiSi master alloy, sponge zirconium, and titanium dioxide, and formulate them according to the following composition range; S1.

2. Three-stage vacuum self-consuming arc melting is adopted to obtain ingots with uniform composition and no metallurgical defects. S1.3 After removing surface defects from the ingot, cut off the ingot riser; S1.

4. Samples were taken from the head, middle, and tail of the ingot to analyze its chemical composition. S2. Ingot blanking: After heating the ingot to 100-200°C above the β phase transformation temperature, blanking is carried out. The total deformation of the blank after blanking and forging is ≥80%. S3, Intermediate forging I: The billet is heated to 10-40°C below the β phase transformation temperature and forged 2-4 times, with a deformation of ≥50% per forging; S4, β-forging modified forging: The billet is heated to 20°C above the β phase transformation temperature and forged in one pass, with a deformation amount ≥80% in one pass; S5, Intermediate forging II: The billet is heated to 20-40°C below the β phase transformation temperature and forged 2-4 times, with a deformation of ≥50% per forging; S6. Heat the billet to 20-40°C below the β phase transformation temperature and shape it to the required specifications; S7. According to the requirements of the forging, cut the blank to the required size and then machine it. S8. Perform ultrasonic testing on the billet; S9. Heat the billet to 20-40°C below the β phase transformation temperature, and place it in the corresponding mold to forge to the required forging size; S10. Perform solution treatment and aging on the forgings to complete the preparation of high-temperature titanium alloy forgings.

2. The method for preparing high-temperature titanium alloy forgings for aerospace structural components according to claim 1, characterized in that, The titanium alloy forging has a tensile strength of up to 530 MPa at a temperature of 650°C.

3. The method for preparing high-temperature titanium alloy forgings for aerospace structural components according to claim 1, characterized in that, The residual deformation of the titanium alloy forging is ≤2% at a temperature of 650℃ and a stress of 300MPa.

4. The method for preparing high-temperature titanium alloy forgings for aerospace structural components according to claim 1, characterized in that, In S10, The process parameters for solution treatment are: holding at 50–80°C below the β phase change temperature for 60–150 min, and using oil cooling or water cooling as the refrigeration method; The process parameters for aging treatment are: holding at 500℃~600℃ for 240~480min, and air cooling is used for refrigeration.

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