Preparation method of high-strength titanium alloy forge piece

Abstract

The invention discloses a preparation method of a high-strength titanium alloy forge piece, which comprises the following steps: selecting a titanium alloy cast ingot with qualified chemical components, pretreating the outer surface, heating the titanium alloy cast ingot to a process temperature, then carrying out cogging treatment, heating a blank to the process temperature, then carrying out heat preservation, and carrying out two-upsetting and two-drawing forging. Performing furnace cooling after forging is completed, heating the blank to a process temperature and then performing multi-heating forging, performing furnace cooling after forging is completed to obtain a titanium alloy forging stock, performing ultrasonic inspection on the titanium alloy forging stock, heating the titanium alloy forging stock to the process temperature and performing heat preservation, and putting the titanium alloy forging stock into a mold with a corresponding size for forming and forging to obtain the titanium alloy forging. Carrying out heat treatment on the titanium alloy forge piece, carrying out finish machining on the titanium alloy forge piece, and carrying out mechanical property detection on the titanium alloy forge piece subjected to finish machining; the structural design is reasonable, the structural strength is guaranteed, and the forging period and cost are remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy forgings, and more specifically, to a method for preparing a high-strength titanium alloy forging. Background Art

[0002] Titanium alloy is a new important structural material used in the aerospace industry. Its specific gravity, strength and operating temperature are between those of aluminum and steel, but it is stronger than aluminum and steel and has excellent resistance to seawater corrosion and ultra-low temperature performance.

[0003] The density of titanium alloy is generally around 4.51g / cm3, which is only 60% of that of steel. Some high-strength titanium alloys exceed the strength of many alloy structural steels. Therefore, the specific strength of titanium alloy is much greater than that of other metal structural materials, and parts with high unit strength, good rigidity and light weight can be made. Aircraft engine components, frames, skins, fasteners and landing gear all use titanium alloys.

[0004] Since titanium alloys often contain five or more alloying elements, the alloy composition is complex, and the phase change process during heating is very complex, the forging temperature is difficult to control. Often, the unreasonable temperature setting will cause cracks in the alloy forging process. A lot of grinding is required after each forging. If the cracks are serious, it will make the product difficult to form, affecting the strength performance during use. Therefore, we proposed a preparation method for high-strength titanium alloy forgings. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a high-strength titanium alloy forging to overcome the technical problems existing in the prior art.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention provides the following technical solutions:

[0007] A method for preparing a high-strength titanium alloy forging comprises the following steps:

[0008] Step 1: Select titanium alloy ingots with qualified chemical composition and pre-treat the outer surface;

[0009] Step 2: heating the titanium alloy ingot to the process temperature and then performing a blanking process;

[0010] Step 3: Heat the blank to the process temperature and keep it warm, perform two upsetting and two drawing forging, and cool it with the furnace after forging is completed;

[0011] Step 4: After heating the blank to the process temperature, perform multi-fire forging, and after forging, cool it with the furnace to obtain a titanium alloy forging blank;

[0012] Step 5: Conduct ultrasonic testing on the titanium alloy forging billet;

[0013] Step 6: Heat the titanium alloy forging billet to the process temperature and keep it warm, then put it into a mold of corresponding size for forging to obtain a titanium alloy forging;

[0014] Step 7: heat treating the titanium alloy forging;

[0015] Step 8: Finishing the titanium alloy forgings;

[0016] Step 9: Test the mechanical properties of the titanium alloy forgings after fine processing.

[0017] Preferably, in a method for preparing a high-strength titanium alloy forging, the pretreatment operation in step one includes removing surface defects of the ingot, cutting off the riser and bottom of the titanium alloy ingot, and chamfering the end surface.

[0018] Preferably, in a method for preparing a high-strength titanium alloy forging, the process temperature for the blanking treatment in step 2 is 1150°C.

[0019] Preferably, in a method for preparing a high-strength titanium alloy forging, the process temperature in step three is 1050° C.-1100° C. and the holding time is 5 h-6 h.

[0020] Preferably, in a method for preparing a high-strength titanium alloy forging, the process temperature in step four is 970°C-1020°C, the holding time is 3h-5h, and 3-4 fire forgings are used in step four.

[0021] Preferably, in a method for preparing a high-strength titanium alloy forging, the process temperature in step six is ​​970° C.-1020° C. and the holding time is 3 h-4 h.

[0022] Preferably, in a method for preparing a high-strength titanium alloy forging, the heat treatment in step seven adopts a solid solution plus aging treatment.

[0023] Preferably, in a method for preparing a high-strength titanium alloy forging, in step eight, fine processing is performed according to the required size of the finished forging.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The structural design of the present invention is reasonable, the heating temperature and holding time are accurately controlled during the forging process, the obtained titanium alloy forging has fine and uniform microstructure, the mechanical properties of the forging meet the technical requirements, and the furnace cooling method is adopted to effectively reduce the generation of surface cracks and ensure the structural strength;

[0026] 2. The present invention breaks the as-cast structure through a series of deformation operations during the forging process, which can forge internal porosity defects, optimize the structure and performance of the material, and ensure structural strength;

[0027] 3. The present invention adopts solid solution and aging treatment processes to achieve excellent strength and toughness matching of titanium alloy forgings, with fewer overall forging fires, significantly reduced forging cycles and costs, and enhanced process controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the specific implementation methods will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] This embodiment is a method for preparing a high-strength titanium alloy forging, comprising the following steps:

[0032] Step 1: Select titanium alloy ingots with qualified chemical composition and pre-treat the outer surface. Ingot pre-treatment refers to a series of treatments on raw materials before ingot production to ensure the quality and performance of the ingot. This process includes but is not limited to the pre-treatment of alloy ingots, which aims to optimize the physical and chemical properties of the ingots through specific processes and techniques to meet specific usage requirements. There are various methods and techniques for pre-treatment, which in this embodiment include removing surface defects of the ingots, cutting off the riser and bottom of the titanium alloy ingots, and chamfering the end faces.

[0033] Step 2: After heating the titanium alloy ingot to the process temperature, the blanking treatment is carried out. The process temperature is 1150℃. After heating the titanium alloy ingot to the process temperature, the blanking treatment is an important hot working process, which aims to improve the physical properties and surface quality of the titanium alloy ingot, while improving production efficiency and product yield. This process involves heating, insulation, blanking forging, etc. During the heating process of the titanium alloy ingot, a specific heating method needs to be adopted to ensure that the ingot is heated evenly to avoid product quality problems caused by uneven temperature. After reaching the set process temperature, the ingot needs to be kept at this temperature for a period of time to ensure that the internal temperature of the ingot is uniform, which also helps to eliminate internal stress and improve the organizational structure of the ingot. The ingot after insulation is placed on a press for blanking forging. The purpose of this step is to forge the ingot into the desired shape and size. By controlling the forging temperature and pressure, a titanium alloy billet with good surface quality and internal structure can be obtained.

[0034] Step 3: Heat the billet to the process temperature and keep it warm. The medium process temperature is 1050℃-1100℃, and the holding time is 5h-6h. Perform two upsetting and two drawing forging, that is, the first upsetting and the first drawing, and the subsequent second upsetting and the second drawing. After the forging is completed, cool it with the furnace; the two upsetting and two drawing forging process mainly includes the following steps. The first upsetting is mainly to increase the forging ratio, while breaking the cast structure and forging the internal porosity defects. The diameter and the height of the billet after the first upsetting have an important influence on the subsequent process parameter control. Immediately after the first upsetting, the first drawing is the most important deformation stage for breaking the cast structure and forging the internal hole defects. This step is crucial for repairing hole defects and controlling the morphology of inclusions. The deformation and closure of the hole defects are guaranteed by large plastic deformation. At the same time, high temperature insulation provides time and temperature guarantee for atomic diffusion and recrystallization in the welding stage. After the first drawing, the second upsetting is performed. The purpose of this step is to further deal with the defects inside the blank, promote grain growth and composition homogenization through deformation and high-temperature forging, and complete the repair process. After the second upsetting, the second drawing is carried out. This step is similar to the first drawing, but because there is more operating experience and data support, the control of process parameters is more precise, which helps to further improve the performance of the material. Through this series of process flows, not only can the internal holes and defects be effectively broken and forged, but the plasticity and toughness of the material can also be significantly improved, thereby improving the overall performance of the material.

[0035] Step 4: After heating the blank to the process temperature, perform multiple forging. After forging, cool it with the furnace to obtain a titanium alloy forging blank. The process temperature is 970℃-1020℃, the holding time is 3h-5h, and 3-4 forgings are adopted. Through multiple heating and forging processes, the grains are refined, the organizational properties are improved, and the required shape and size are achieved. Multi-fire forging helps to break up the cast structure and promote organizational homogenization, thereby improving the plasticity and toughness of the forging blank. Through repeated forging and correction, the required shape and size can be gradually approached, and the dimensional accuracy of the forging blank is improved. During the forging process, the heating temperature needs to be strictly controlled to ensure that the titanium alloy maintains appropriate plasticity and deformation ability during the forging process. The deformation amount of each fire should be controlled within a reasonable range to avoid excessive deformation causing cracking of the forging blank or performance degradation.

[0036] Step 5: Perform ultrasonic inspection on titanium alloy forgings to confirm that there are no cracks or internal injuries in the forgings; use the propagation characteristics of ultrasound in the material medium, that is, the sound wave will lose energy during the propagation of the medium, and reflection will occur when encountering the interface of the medium. By measuring the sound propagation time between the incident sound wave and the received sound wave, the distance between the reflection point and the incident point can be known, so as to find the defects inside the material. Ultrasonic inspection of titanium alloy forgings is a key quality control step, which aims to ensure that there are no defects inside the forgings or the defects are within an acceptable range. During the inspection, clean the surface of the forgings, remove impurities such as oil, oxides, etc., to ensure that the ultrasound can propagate smoothly and accurately receive the reflected signal, place the probe on the surface of the forgings, and scan along the predetermined path to ensure that all areas of the forgings are fully covered. Observe the defect signal on the display screen and record information such as the location, size and shape of the defects.

[0037] Step six: heat the titanium alloy forging billet to the process temperature and keep it warm, put it into the corresponding size mold for forging to obtain titanium alloy forgings. The process temperature is 970℃-1020℃ and the insulation time is 3h-4h; put the titanium alloy forging billet into the mold of predetermined shape, heat the billet to the appropriate forging temperature to improve its plasticity and reduce deformation resistance, and plastically deform the forging billet under the action of the press to fill the mold cavity and form a forging of the desired shape. Strictly control the heating temperature and time to avoid overheating or overburning that may cause the billet performance to deteriorate. The die forging process has the advantages of high production efficiency, high material utilization rate, high dimensional accuracy of forgings, good surface quality, etc., and can produce high-quality and high-precision titanium alloy forgings.

[0038] Step 7: Heat treatment of titanium alloy forgings, specifically using solution plus aging treatment; solution plus aging treatment of titanium alloy forgings is a combined heat treatment process, which aims to comprehensively strengthen the performance of titanium alloys through two steps of solution treatment and aging treatment. Solution treatment is the process of heating the titanium alloy forgings to a certain temperature, keeping it warm for a period of time, and then rapidly cooling it to room temperature. Its main purpose is to fully dissolve the alloying elements in the titanium alloy into the matrix phase to form a uniform solid solution, and eliminate or reduce the internal stress and work hardening phenomenon in the alloy, while retaining the metastable phase that can produce aging strengthening. Aging treatment is the process of heating the titanium alloy forgings to an appropriate temperature after solution treatment, keeping it warm for a period of time, and then cooling it to room temperature. Its main purpose is to decompose or precipitate the metastable phase retained during the solution treatment process to form a fine strengthening phase, thereby improving the strength and hardness of the titanium alloy. This combined heat treatment process can significantly improve the strength, hardness and corrosion resistance of titanium alloys while maintaining good plasticity and toughness.

[0039] Step 8: Finish the titanium alloy forgings according to the required size of the finished forgings; clarify the final size requirements of the finished forgings, including length, width, height and any special shape or contour requirements, select appropriate processing equipment, tools, fixtures and processing paths, etc., ensure that the processing equipment is in good condition, and calibrate and adjust as needed to ensure processing accuracy. During the finishing process, pay special attention to maintaining the surface finish and accuracy of the forgings to avoid scratches, burrs and other defects.

[0040] Step 9: Perform mechanical property testing on the titanium alloy forgings after fine machining. The mechanical property testing is intended to evaluate the behavior of titanium alloy forgings under stress, including its strength, toughness, plasticity and other characteristics, to ensure that the forgings can meet the design requirements and use conditions in actual applications. The mechanical property testing of titanium alloy forgings should follow relevant national or industry standards, such as GB / T (national standard), ASTM (American Society for Testing and Materials Standard), etc. These standards specify the specific requirements of the test method, the preparation and size of the specimen, the accuracy and calibration of the test equipment, etc.

[0041] The embodiments described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have all been recorded in the claims.

Claims

1. A method for preparing a high-strength titanium alloy forging, characterized in that: The following steps are involved: Step 1: Select titanium alloy ingots with qualified chemical composition and pre-treat the outer surface; Step 2: heating the titanium alloy ingot to the process temperature and then performing a blanking process; Step 3: Heat the blank to the process temperature and keep it warm, perform two upsetting and two drawing forging, and cool it with the furnace after forging is completed; Step 4: After heating the blank to the process temperature, perform multi-fire forging, and after forging, cool it with the furnace to obtain a titanium alloy forging blank; Step 5: Conduct ultrasonic testing on the titanium alloy forging billet; Step 6: Heat the titanium alloy forging billet to the process temperature and keep it warm, then put it into a mold of corresponding size for forging to obtain a titanium alloy forging; Step 7: heat treating the titanium alloy forging; Step 8: Finishing the titanium alloy forgings; Step 9: Test the mechanical properties of the titanium alloy forgings after fine processing.

2. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: The pretreatment operation in step 1 includes removing surface defects of the ingot, cutting off the riser and bottom of the titanium alloy ingot, and chamfering the end surface.

3. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: In step 2, the process temperature for the blanking treatment is 1150°C.

4. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: In step 3, the process temperature is 1050°C-1100°C and the insulation time is 5h-6h.

5. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: In step 4, the process temperature is 970°C-1020°C, the holding time is 3h-5h, and 3-4 fire forging is adopted in step 4.

6. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: In step six, the process temperature is 970°C-1020°C and the insulation time is 3h-4h.

7. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: In step seven, the heat treatment adopts solid solution plus aging treatment.

8. The method for preparing a high-strength titanium alloy forging according to claim 1, characterized in that: In step eight, the forging is finished according to the required size.

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