Thermoforming method of titanium alloy

Abstract

The invention discloses a thermal forming method of titanium alloy, and belongs to the technical field of titanium alloy process machining. Cleaning treatment is conducted, specifically, the titanium alloy blank is subjected to decontamination treatment; cutting and blanking are conducted, specifically, the blank obtained after decontamination treatment is cut according to the size requirement of a standard part, and a to-be-hot-machined material is formed; (S3); a mold is selected, specifically, a machining mold resistant to high temperature and high pressure is selected, and the machining mold is filled with the material to be subjected to hot machining; and flame gun equipment is adopted for hot machining, the machining mold is arranged in the flame gun equipment for hot machining, the heating temperature is selected according to the types of the materials to be subjected to hot machining and the requirements of the hot forming technology, and the machining efficiency of the Korean aviation workpieces is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy processing technology, and in particular relates to a hot forming method of titanium alloy. Background Art

[0002] At present, there are many problems in the titanium alloy forming method, among which the low forming precision and many internal defects are more prominent. In the traditional titanium alloy forming process, when it is necessary to manufacture products with complex shapes, stress concentration often occurs, resulting in problems such as fine cracks that are difficult to detect with the naked eye, and the strength and toughness cannot meet high requirements. During the cold deformation process, titanium alloy has poor deformation coordination and serious local stress concentration. When the local stress exceeds the strength limit of the material, cracks are likely to occur. For example, during the cold bending process, the outer side of the bend is subjected to tensile stress, and cracks will appear if the stress is too large. Rebound is a more prominent problem. The elastic modulus of titanium alloy is relatively low. After forming processes such as cold stamping, the parts are prone to rebound, resulting in deviations between the final shape and the designed target shape. For example, some cold-formed titanium alloy thin plates may not meet the required accuracy after demolding, resulting in reduced manufacturing efficiency of aviation workpieces. Summary of the invention

[0003] In view of this, the hot forming method of titanium alloy provided by the present invention solves the technical problem of low efficiency in processing aviation workpieces by traditional processes.

[0004] A hot forming method for titanium alloy, the hot forming method comprising:

[0005] S1: Cleaning treatment, decontamination treatment of titanium alloy blanks,

[0006] S2: Cutting and blanking: the decontaminated blank is cut according to the size requirements of standard parts to form the material to be heat-processed;

[0007] S3: Selection of a mold, selecting a processing mold with high temperature and high pressure resistance, the processing mold is formed by steel H13 material, and the material to be heat-processed is filled into the processing mold;

[0008] S4; using a flame gun device for heat processing, wherein the processing mold is placed in the flame gun device for heat processing, and the heating temperature is selected according to the type of the material to be heat processed and the requirements of the hot forming process.

[0009] The technical beneficial effects of the present invention are:

[0010] During the cold deformation process of titanium alloy, local stress concentration is serious due to its poor deformation coordination. When the local stress exceeds the strength limit of the material, cracks are likely to occur. For example, during the cold bending process, the outer side of the bend is subjected to tensile stress. If the stress is too large, cracks will appear, and springback is a more prominent problem. The titanium alloy is heated at 600℃-950℃ using flame gun equipment. The elastic modulus of titanium alloy is relatively high. After cold stamping and other forming processes, the parts are not easy to rebound, so that the final shape and the designed target shape have a small deviation, avoiding the situation where the size may not meet the required accuracy after demolding. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0012] Figure 1 is a process flow chart of the method of the present invention;

[0013] Figure 2 Schematic diagram of the change of yield strength of TA12A titanium alloy with temperature. DETAILED DESCRIPTION

[0014] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0015] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0016] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0017] like Figure 1 The hot forming method of the titanium alloy shown in the figure comprises:

[0018] S1; cleaning treatment, the titanium alloy blank is decontaminated. Specifically, the blank is cleaned with alkaline solution to remove oil stains, and the degreased blank is pickled to remove oxide scale. The purpose is to ensure that the surface of the blank is clean so that the material can better contact and flow with the mold during the hot forming process. The alkaline solution and the acid solution can be the titanium alloy treatment solution in the prior art, which will not be described in detail.

[0019] S2: Cutting and blanking. The decontaminated blank is cut according to the size requirements of standard parts to form the material to be heat-processed. Specifically,

[0020] Common cutting methods include laser cutting and wire cutting. Laser cutting has high precision and high speed, and can cut complex shapes; wire cutting is suitable for the preparation of billets with extremely high precision requirements. According to the size requirements of hot-formed parts, titanium alloy billets are cut, especially for the blanking of some small precision parts.

[0021] S3; Selection of molds. Select processing molds with high temperature and high pressure resistance. The processing molds are formed with steel H13 material, and the material to be hot-processed is filled into the processing molds. Since titanium alloys are formed at high temperatures, the molds must withstand high temperatures and high pressures. Therefore, it is necessary to select mold materials that are resistant to high temperatures and have high strength, such as hot working die steel H13. This material has good toughness and thermal fatigue resistance at high temperatures, and can ensure that the molds do not deform or crack during multiple hot forming processes.

[0022] S4; using a flame gun device for heat processing, wherein the processing mold is placed in a flame gun device for heat processing, and the heating temperature is selected according to the type of material to be heat processed and the requirements of the hot forming process, specifically,

[0023] The present invention provides for the first time a method of heating titanium alloy by a flame gun, which has a fast heating speed, high thermal efficiency, is economical and efficient, and can locally heat the blank and heat the fixed part of the workpiece. If only the edge or local area of ​​a large component needs to be hot formed, the flame gun can accurately concentrate the heat in the target area without affecting other parts that do not need to be heated. Compared with some large hot forming equipment, the equipment cost and operating cost of the flame gun are relatively low. It has a relatively simple structure and does not require complex supporting equipment for installation. It is more economical and practical in some small hot forming processing workshops or simple manual hot forming scenarios. The flame gun heats the titanium alloy in the mold in the process chamber, and the heating temperature of the flame gun of the flame gun equipment needs to be set to 600℃-950℃. The purpose is to reduce the yield strength of the TA12A titanium alloy material, improve the plasticity of the material, and reduce the external force required for forming, thereby avoiding defects such as cracking of the material.

[0024] Further, such as Figure 2 As shown, when the blank is TA12A titanium alloy, the heating temperature of the flame gun is 600℃-650℃. It should be pointed out that in the temperature range from room temperature to 400℃, due to the high temperature strengthening effect, the yield strength of the alloy will increase, and in the temperature range of 400℃~550℃, the distortion of the TA12A titanium alloy crystal structure will lead to the accumulation of dislocations, which restricts the movement of dislocations, thereby reducing the plasticity of the TA12A titanium alloy and the yield strength. When the temperature exceeds 550℃, the alloy's organizational stability decreases and the phase structure may change, such as the growth of the α phase and the increase of the β phase, resulting in a significant decrease in the yield strength. TA12A titanium alloy yield strength changes with temperature Figure 2 As shown, the temperature of 600℃-650℃ can reduce the yield strength of the material, improve the plasticity of the material, and reduce the external force required for forming, thereby avoiding defects such as cracking of the material;

[0025] When the blank is TC4 titanium alloy, the heating temperature of the flame gun is 700℃-850℃, or, when the blank is TA15 titanium alloy, the heating temperature of the flame gun is 850℃-950℃. Different titanium alloys have different hot forming temperatures due to their different compositions, and the specific process also needs to comprehensively consider multiple factors such as deformation rate and holding time to accurately determine the appropriate temperature.

[0026] As a specific implementation method provided in this case, the processing mold is preheated before placing the material to be processed, and the preheating temperature is between 300℃ and 500℃. The purpose is to reduce the temperature difference between the titanium alloy blank and the mold, avoid the temperature of the blank dropping suddenly when it contacts the mold, resulting in poor material fluidity, and also reduce the thermal stress of the mold and extend the service life of the mold.

[0027] Furthermore, the inner surface of the processing mold is provided with a high temperature resistant and wear resistant protective layer, which is used to reduce the friction between the processing mold and the material to be processed during hot processing. Preferably, the protective layer is a ceramic coating or a titanium carbide (TiC) coating, which can effectively resist the friction and erosion of the titanium alloy at high temperature, and can also play a role of heat insulation, reducing the temperature variation of the mold base. Due to the poor fluidity of titanium alloy during cold processing, uneven filling may occur. In forming processes such as cold heading, the metal cannot fill the mold cavity well, resulting in incomplete shape of the part or the size not meeting the requirements. When titanium alloy is cold formed, the friction between the mold and the workpiece surface is large, which is easy to cause surface scratches. Moreover, during the high-pressure cold processing process, defects such as local depressions or protrusions may appear on the surface of the material. The hydrogen absorption process during the hot forming of titanium alloys requires the control of the hydrogen content. In addition, the setting of the protective layer can reduce the friction between the mold and the workpiece surface during cold forming of the titanium alloy, making it less likely to cause scratches on the workpiece surface. In addition, during the high-pressure cold processing process, it can avoid defects such as local depressions or protrusions on the workpiece surface.

[0028] Generally, high temperature protection, smoke and harmful gas protection are also required during processing. Specifically,

[0029] High temperature protection: Since the hot forming process involves high temperatures, operators need to wear high temperature resistant protective clothing, including fireproof and heat-insulating clothing, high temperature resistant gloves and protective masks, etc. These protective equipment can prevent operators from being burned by high temperature titanium alloy billets or molds.

[0030] Protection against smoke and harmful gases: Some smoke and harmful gases may be generated during the heating of titanium alloys. Operators should wear gas masks and protective masks, and the workplace needs to have good ventilation equipment, such as installing large ventilation fans or exhaust systems, to reduce the concentration of harmful gases and smoke and protect the health of operators.

[0031] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A hot forming method of titanium alloy, characterized in that: The thermoforming method comprises: S1: cleaning treatment, decontamination treatment of the titanium alloy blank; S2: Cutting and blanking: the decontaminated blank is cut according to the size requirements of standard parts to form the material to be heat-processed; S3: Selecting a mold, selecting a processing mold with high temperature and high pressure resistance, and filling the material to be heat-processed into the processing mold; S4; using a flame gun device for heat processing, wherein the processing mold is placed in the flame gun device for heat processing, and the heating temperature is selected according to the type of the material to be heat processed and the requirements of the hot forming process.

2. The hot forming method according to claim 1, characterized in that: S1 includes: The blank is cleaned with alkali solution to remove oil stains, and the blank after degreasing is pickled to remove oxide scales.

3. The hot forming method according to claim 1, characterized in that: S2 includes: According to the precision requirements of the parts to be processed, the decontaminated blanks are cut by laser cutting or wire cutting.

4. The hot forming method according to claim 1, characterized in that: S4 includes: The heating temperature is determined, wherein the heating temperature is set according to the type of titanium alloy and the requirements of the hot forming process.

5. The hot forming method according to claim 1, characterized in that: The processing mold in S3 is made of steel H13 material.

6. The hot forming method according to claim 5, characterized in that: The processing mold is preheated before placing the material to be processed by heat, and the preheating temperature is 300℃-500℃.

7. The hot forming method according to claim 5, characterized in that: The inner surface of the processing mold is provided with a high temperature resistant and wear resistant protective layer, and the protective layer is used to reduce the friction between the processing mold and the material to be heat processed during heat processing.

8. The hot forming method according to claim 1, characterized in that: S4 includes that the heating temperature of the flame gun of the flame gun equipment is 600°C-950°C.

9. The hot forming method according to claim 8, characterized in that: The blank is TA12A titanium alloy, and the heating temperature of the flame gun is 600°C-650°C.

10. The hot forming method according to claim 8, characterized in that: The blank is TC4 titanium alloy, and the heating temperature of the flame gun is 700°C-850°C; or, the blank is TA15 titanium alloy, and the heating temperature of the flame gun is 850°C-950°C.

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