Machining method of large thermal strength titanium alloy forge piece

Abstract

The invention discloses a processing method of a large thermal strength titanium alloy forge piece, which comprises the following steps of: mixing a single electrode, pressing into an electrode block, welding the pressed electrode block into a strip-shaped electrode, putting the electrode into a vacuum consumable electric arc furnace, and carrying out vacuum melting for 2-3 times to obtain a thermal strength titanium alloy cast ingot; the method comprises the following steps: brushing an antioxidant protective coating on the surface of a hot-strength titanium alloy ingot, heating and preserving heat after the coating is dried, discharging an ingot blank, transferring the ingot blank to a forging machine for cogging forging, performing multi-heating-number forging on a titanium alloy forging blank above and below a phase transformation point, discharging the titanium alloy forging blank, and putting the titanium alloy forging blank into a mold for finish forging forming, carrying out solid solution aging treatment on the semi-finished thermal strength titanium alloy forge piece; the die is reasonable in structural design, the service life of the die is guaranteed, it is guaranteed that the quality and performance of the thermal strength titanium alloy forge piece meet the requirements, and various application requirements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy forgings, and more specifically, to a processing method for large-scale heat-resistant titanium alloy forgings. 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] Large heat-resistant titanium alloy forgings are titanium alloy forgings with excellent high-temperature strength and heat resistance. They are mainly used to manufacture compressor disks, blades, drums and other parts of aircraft engines, and can also be used to manufacture aircraft structural parts. This forging exhibits excellent heat-resistant properties below 500°C, including high-temperature strength and creep resistance, and has good hot processing properties, and can be welded and machined in various ways.

[0004] Heat-resistant titanium alloys have poor plasticity, a narrow hot working temperature window, and are prone to cracking during hot working. Therefore, large heat-resistant titanium alloy forgings are generally die forged or isothermal forged, which requires the use of high-strength heat-resistant steel to manufacture the mold. The high forging temperature results in a short mold life and a significant increase in mold costs. For some heat-resistant titanium alloy forgings with simpler shapes, this will lead to a significant increase in their manufacturing costs. To this end, we propose a processing method for large heat-resistant titanium alloy forgings. Summary of the invention

[0005] The purpose of the present invention is to provide a processing method for large heat-resistant titanium alloy forgings 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 processing a large heat-resistant titanium alloy forging comprises the following steps:

[0008] Step 1: Select a master alloy containing Mo, Zr, Al, small-grained sponge zirconium, aluminum beans, TiO2 powder, C powder and small-grained sponge titanium to mix a single electrode, and then press it into an electrode block;

[0009] Step 2: Weld the pressed electrode blocks into long strip electrodes;

[0010] Step 3: placing the electrode in a vacuum consumable arc furnace for 2-3 times of vacuum melting to obtain a heat-resistant titanium alloy ingot;

[0011] Step 4: Apply an anti-oxidation protective coating on the surface of the heat-resistant titanium alloy ingot, and heat and keep warm after the coating is dried;

[0012] Step 5: The ingot is taken out of the furnace and transferred to a forging machine for forging to obtain a titanium alloy forging billet;

[0013] Step 6: heating the titanium alloy forging billet to the process temperature and keeping the temperature, and performing multiple fire forging above and below the phase transformation point on the titanium alloy forging billet;

[0014] Step 7: Mechanically process the titanium alloy forging billet, remove surface crack defects, apply a lubricating and thermal insulation coating on its surface, and heat and insulate after the coating is dried;

[0015] Step 8: After the titanium alloy forging billet is taken out of the furnace, it is placed in a mold for final forging to obtain a semi-finished heat-resistant titanium alloy forging;

[0016] Step nine: performing solid solution aging treatment on the semi-finished heat-resistant titanium alloy forging to obtain a finished heat-resistant titanium alloy forging;

[0017] Step 10: Conduct quality inspection on the finished heat-resistant titanium alloy forgings.

[0018] Preferably, in a method for processing a large heat-resistant titanium alloy forging, the welding method in step 2 specifically adopts argon shielded plasma welding.

[0019] Preferably, in a method for processing large heat-resistant titanium alloy forgings, the smelting current in step three is 5-12KA, and the smelting voltage is controlled at 26-45V.

[0020] Preferably, in a method for processing a large heat-resistant titanium alloy forging, the heating temperature in step 4 is 1150° C. and the holding time is 4 hours.

[0021] Preferably, in a processing method for a large heat-resistant titanium alloy forging, the multi-fire forging in step six is ​​changed to 3-4 fire forging, the temperature is 1050°C-940°C, and the holding time is 3h.

[0022] Preferably, in a processing method for a large heat-resistant titanium alloy forging, the heating temperature in step seven is 1020°C-970°C and the holding time is 3 hours.

[0023] Preferably, in a processing method for a large heat-resistant titanium alloy forging, the solid solution aging treatment in step nine is a solid solution and aging treatment.

[0024] Preferably, in a processing method for a large heat-resistant titanium alloy forging, the quality inspection items in step ten include chemical composition analysis, mechanical property testing and metallographic structure analysis.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The structural design of the present invention is reasonable, the heating temperature and the holding time are accurately controlled during the forging process, the obtained titanium alloy forging has a fine and uniform microstructure, the mechanical properties of the forging meet the technical requirements, the overall forging number is small, the forging cycle and the cost are significantly reduced, and the final forging is carried out in the mold after being taken out of the furnace, which is conducive to ensuring the life of the mold;

[0027] 2. The present invention performs surface spraying treatment on the heat-resistant titanium alloy during the forging process, which can improve the surface quality and corrosion resistance of the titanium alloy, ensure the subsequent use effect, ensure that the quality and performance of the heat-resistant titanium alloy forgings meet the requirements, and meet the needs of various applications;

[0028] 3. The present invention adopts solid solution and aging treatment processes to achieve excellent strength and toughness matching of titanium alloy forgings, which can effectively reduce the occurrence of surface cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] This embodiment is a method for processing a large heat-resistant titanium alloy forging, comprising the following steps:

[0033] Step 1: Select intermediate alloys containing Mo, Zr, Al, small-grained sponge zirconium, aluminum beans, TiO2 powder, C powder and small-grained sponge titanium to mix a single electrode, and then press it into an electrode block. The main purpose of the mixing is to evenly mix the electrode materials to ensure that the electrode block can show consistent and stable performance during subsequent use. According to the shape and size requirements of the electrode block, prepare the corresponding mold and fill the evenly mixed electrode material into the mold. During the filling process, it is necessary to ensure that the material is evenly distributed to avoid voids or uneven density. The main purpose of pressing is to press the evenly mixed electrode material into an electrode block with a certain shape, density and strength for subsequent installation and use. During the pressing process, it is necessary to control parameters such as pressing pressure and holding time to ensure that the electrode block can achieve the required density and strength.

[0034] Step 2: The pressed electrode blocks are welded into long strip electrodes. The specific welding method is argon shielded plasma welding; the electrode blocks are cleaned to remove impurities such as oil and oxides on the surface to ensure welding quality. According to the characteristics of the electrode blocks and welding materials, the electrode blocks are preheated as needed to reduce welding stress and improve welding quality. According to the material of the electrode blocks and welding requirements, suitable welding materials such as welding wire and welding rod are selected. After welding, the weld is inspected to ensure that the weld quality is good and there are no defects such as cracks and pores. Subsequently, the long strip electrodes after welding are cleaned to remove impurities such as welding slag and spatter.

[0035] Step 3: Place the electrode in a vacuum consumable arc furnace for 2-3 vacuum melting, with a melting current of 5-12KA and a melting voltage of 26-45V to obtain a heat-resistant titanium alloy ingot; under vacuum or inert gas protection, melt and refine the metal consumable electrode by arc heating, and finally obtain a high-purity, high-performance alloy ingot. This method is widely used in the preparation of titanium alloys because it can effectively remove impurities and gases in the metal and improve the purity and performance of the metal. The titanium alloy is further purified by multiple melting to reduce the inclusions and gas content, thereby obtaining a titanium alloy ingot with excellent heat-resistant properties. This ingot can be used as a raw material for manufacturing high-performance components in the fields of aviation, aerospace, nuclear energy, etc.

[0036] Step 4: Apply an anti-oxidation protective coating on the surface of the heat-resistant titanium alloy ingot, and heat and keep the coating after it dries. The heating temperature is 1150℃ and the insulation time is 4h. Applying an anti-oxidation protective coating on the surface of the heat-resistant titanium alloy ingot is an important protective measure, which can significantly improve the anti-oxidation performance and service life of the titanium alloy in a high temperature environment. When selecting and preparing the anti-oxidation protective coating, it can be selected according to actual needs. The use of platinum-aluminide coating can significantly improve the high-temperature anti-oxidation performance of titanium alloy, and the use of RLHY-31 high-temperature resistant anti-oxidation coating can form a dense protective layer on the surface of the titanium alloy, effectively preventing oxidation and decarburization at high temperatures.

[0037] Step 5: Transfer the ingot to the forging machine for open forging to obtain a titanium alloy forging. Open forging is the production process of forging a metal ingot into a billet with certain specifications and properties. For titanium alloys, this step is particularly critical because it directly affects the difficulty of the subsequent forging process and the quality of the forging. Most open forging is carried out by free forging. Through the pressure of the forging machine, the titanium alloy ingot undergoes plastic deformation to obtain the required shape and size. The ingot needs to be preheated before it is taken out of the furnace to remove impurities and oil stains on the surface to ensure the smooth progress of the forging process. After the ingot is taken out of the furnace, it should be quickly transferred to the forging machine for processing. During the transfer process, care should be taken to avoid collision or scratching of the ingot. Under the pressure of the forging machine, the ingot is free forged. When forging, the principle of "one light, two heavy and three small" should be followed, that is, light pressure and fast forging during the initial forging, and the pressure should be gradually increased as the deformation increases.

[0038] Step 6: Heat the titanium alloy forging billet to the process temperature and keep it warm. The titanium alloy forging billet is forged for multiple times above and below the phase transformation point. The multi-fire forging is 3-4 fires, the temperature is 1050℃-940℃, and the holding time is 3h. Multi-fire forging refers to the process of forging the titanium alloy forging billet. Through multiple heating and forging operations, the material undergoes plastic deformation above the phase transformation point, thereby achieving the purpose of refining the grains, improving the organizational structure and improving the performance. This forging method can make full use of the good plasticity and deformation ability of titanium alloy at high temperature to realize the manufacture of complex shapes and high-performance forgings. Multi-fire forging can adjust the forging process parameters and heat treatment system according to the needs of different application fields to obtain titanium alloy forgings with specific organizational structure and mechanical properties. Appropriate cleaning and cooling work is required between each heating and forging to avoid the influence of impurities and oxide scale on the quality of the forging billet.

[0039] Step 7: Machining the titanium alloy forging blank, removing the surface crack defects and applying the lubricating thermal insulation coating on its surface, heating and heat preservation after the coating is dried, the heating temperature is 1020℃-970℃, and the heat preservation time is 3h; the selection of lubricating thermal insulation coating should be determined according to the specific application requirements and working environment of the titanium alloy forging blank. Generally speaking, the coating should have good lubricity, thermal insulation and corrosion resistance. Common lubricating thermal insulation coating materials include glass powder, silica aerogel, etc. These materials can maintain stable performance at high temperatures and provide effective protection and lubrication for the forging blank. The lubricating thermal insulation coating can form a lubricating film between the forging blank and the die, reduce the friction coefficient and wear degree, improve the forging efficiency and the quality of the forging. The layer also has certain thermal insulation properties, which can reduce the heat loss of the forging blank during the forging process and maintain the stability and uniformity of the forging blank temperature. During the painting process, it is necessary to pay attention to controlling the thickness and uniformity of the coating to avoid excessive thickness or thinness resulting in a decrease in coating performance.

[0040] Step 8: After the titanium alloy forging billet is taken out of the furnace, it is placed in the mold for final forging to obtain a semi-finished heat-resistant titanium alloy forging. Before the titanium alloy forging billet is placed in the mold, the mold needs to be preheated. The preheating temperature is usually determined according to the type of titanium alloy and the forging process requirements. The preheating time also needs to be determined according to the mold material and size to ensure that the mold maintains a stable temperature throughout the forging process. The mold closes and applies pressure to the forging billet to cause it to plastically deform and fill the mold cavity. During this process, parameters such as forging pressure, forging speed and forging temperature must be strictly controlled to ensure the quality and performance of the forgings.

[0041] Step nine: The semi-finished heat-resistant titanium alloy forgings are subjected to solution aging treatment to obtain finished heat-resistant titanium alloy forgings. The solution aging treatment is a solid solution and aging treatment. This treatment process can eliminate defects and impurities in the alloy, improve the uniformity and stability of the alloy, and at the same time strengthen the matrix of the alloy by precipitating fine second phase particles to improve the mechanical properties of the alloy.

[0042] Step 10: Conduct quality inspection on finished heat-resistant titanium alloy forgings, including chemical composition analysis, mechanical properties test and metallographic structure analysis. Through high-precision analysis methods such as spectral analysis, mass spectrometry or energy spectrum analysis, the content of various elements in the forgings can be determined and compared with the standard values. Mechanical properties tests include strength tests, hardness tests and fracture toughness tests. Metallographic structure analysis is performed by cutting, polishing and corroding the forgings, and then using microscopes and other observation equipment to clearly see the internal grain structure, phase distribution and defects. Through the comprehensive use of these detection methods, the performance and quality of the forgings can be comprehensively evaluated to ensure that they meet the design requirements and meet the actual application needs.

[0043] 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 processing large heat-resistant titanium alloy forgings, characterized in that: The following steps are involved: Step 1: Select a master alloy containing Mo, Zr, Al, small-grained sponge zirconium, aluminum beans, TiO2 powder, C powder and small-grained sponge titanium to mix a single electrode, and then press it into an electrode block; Step 2: Weld the pressed electrode blocks into long strip electrodes; Step 3: placing the electrode in a vacuum consumable arc furnace for 2-3 times of vacuum melting to obtain a heat-resistant titanium alloy ingot; Step 4: Apply an anti-oxidation protective coating on the surface of the heat-resistant titanium alloy ingot, and heat and keep warm after the coating is dried; Step 5: The ingot is taken out of the furnace and transferred to a forging machine for forging to obtain a titanium alloy forging billet; Step 6: heating the titanium alloy forging billet to the process temperature and keeping the temperature, and performing multiple fire forging above and below the phase transformation point on the titanium alloy forging billet; Step 7: Mechanically process the titanium alloy forging billet, remove surface crack defects, apply a lubricating and thermal insulation coating on its surface, and heat and insulate after the coating is dried; Step 8: After the titanium alloy forging billet is taken out of the furnace, it is placed in a mold for final forging to obtain a semi-finished heat-resistant titanium alloy forging; Step nine: performing solid solution aging treatment on the semi-finished heat-resistant titanium alloy forging to obtain a finished heat-resistant titanium alloy forging; Step 10: Conduct quality inspection on the finished heat-resistant titanium alloy forgings.

2. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: The welding method in step 2 specifically adopts argon shielded plasma welding.

3. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: In step 3, the smelting current is 5-12KA, and the smelting voltage is controlled at 26-45V.

4. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: In step 4, the heating temperature is 1150° C. and the holding time is 4 h.

5. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: In step 6, the multi-fire forging is changed to 3-4 fire forging, the temperature is 1050℃-940℃, and the holding time is 3h.

6. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: In step seven, the heating temperature is 1020°C-970°C and the insulation time is 3h.

7. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: The solution-aging treatment in step nine is a solution-aging treatment.

8. The method for processing a large heat-resistant titanium alloy forging according to claim 1, characterized in that: The quality inspection items in step ten include chemical composition analysis, mechanical properties test and metallographic structure analysis.

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