Method for diffusion welding of titanium-aluminum alloy and stainless steel

Abstract

The invention discloses a diffusion welding method for a titanium-aluminum alloy and stainless steel. The diffusion welding method comprises the steps that to-be-welded end faces of the titanium-aluminum alloy and a steel structure are ground, polished and ultrasonically cleaned; placing in a mold in a centering contact manner, and then placing in a vacuum hot-pressing sintering furnace; heating operation is conducted, vacuum diffusion welding is started, the temperature is increased to 450-650 DEG C at the temperature increasing speed of 8-10 DEG C / min, heat preservation is conducted, then the temperature is continuously increased to 800-1000 DEG C, and heat preservation is conducted; heating and pressurizing operation is carried out, pressurizing is started when the temperature reaches 800-1000 DEG C, the speed is 1-5 MPa / min, pressurizing is stopped after 10-30 min, the pressure is 20-50 MPa, and heat preservation and pressure maintaining are continued for 20-80 min; and final treatment is conducted, specifically, the surfaces of the obtained TiAl and steel components are polished and cleaned. The joint without obvious welding defects is obtained, and has the advantages of small deformation, no stress concentration, few cracks, few brittle phases, high room temperature strength and the like.

Description

Technical Field

[0001] The invention relates to a method for diffusion welding titanium aluminum alloy and stainless steel, in particular to a method for manufacturing a diffusion welding joint of TiAl alloy and stainless steel. Background Art

[0002] Titanium-aluminum intermetallic compounds are a kind of metal material with low density, high specific strength, high rigidity and high oxidation resistance. They are mostly used in engine turbine rotor parts to replace high-temperature alloy materials. They can significantly reduce the moment of inertia of turbine rotors and improve the transient response capability of engines. Steel structures are the components that bear the loads of most components. Therefore, the connection between titanium-aluminum alloys and steel structures is the key technology to ensure their use in engines.

[0003] At present, the connection methods of titanium aluminum alloy and steel structure include fusion welding, brazing, friction welding and diffusion welding, etc. The residual stress of fusion welding joint is large, cracks are easy to occur, and the process is complex and difficult to control; the brazing joint has a low melting point eutectic structure, which will damage the high temperature performance of the joint; the friction welding joint is prone to non-uniform plastic deformation, which has great restrictions on the shape and size of the material; the diffusion welding process is simple, easy to operate, the residual stress of the joint is small, the strength is high, and the welding precision is high, but there are still many problems in the specific application of the connection between titanium aluminum alloy and steel structure.

[0004] For example, patent CN115319260A discloses a diffusion welding method for butt joints between two dissimilar materials, TiAl alloy and steel, which uses diffusion welding of a Ti / Al+X ternary laminated foil strip composed of multiple layers of alternately stacked Ti metal layers and Al metal layers and a single layer of X metal layer. However, the bonding of the Ti layer and the Al layer by solid solution is not only limited compared to the bonding degree of the solid solution alloy of the TiAl alloy itself, but also the introduction of a new X element easily leads to segregation and insufficient bonding strength.

[0005] Patent CN110216376A discloses a method for welding dissimilar metals between TiAl-based alloy and 40Cr steel, which uses laser welding to treat the surfaces of TiAl-based alloy, 40Cr steel, pure V thin sheet, and pure Cu thin sheet to be welded, remove scale and grease, and then place the composite intermediate layer between the TiAl-based alloy and the 40Cr steel, and ensure that the V layer is adjacent to the TiAl-based alloy, and the Cu layer is adjacent to the 40Cr steel, and use Nd:YAG pulse laser welding equipment for welding. The industrialization cost of this welding method is high, and more types of elements are introduced, resulting in more prone to crystallization embrittlement.

[0006] Patent CN106141469A discloses a friction-diffusion composite welding method for a TiAl alloy turbine and a quenched and tempered steel shaft, which requires a spindle motor on a friction welding machine to drive an intermediate to rotate at high speed through a spindle and a rotating fixture to apply friction welding, which results in relatively high deformation stress and the need for post-welding slow cooling and tempering treatment. The process is cumbersome, costly, and has a long production cycle.

[0007] Patent CNCN102794578A and others use a new type of Ti-Ni-V-Cr-Cu brazing filler metal to braze titanium aluminum and steel, effectively avoiding the formation of Ti-Fe binary brittle phase, but there are also the following disadvantages: 1. The thermal expansion coefficients of the brazing filler metal and the substrate are quite different, resulting in large internal stress and easy poor bonding; 2. The melting point of titanium is 1668°C, the melting point of aluminum is 660°C, and the melting point of iron is 1538°C. The large temperature difference leads to mutual melting and solidification difficulties during fusion welding; 3. Although the formation of a large number of brittle Ti-Fe metal compounds is avoided, complex components are introduced, and other brittle phases are easily formed during welding. Summary of the invention

[0008] In view of the above defects in the prior art and the current situation where there is still very little research on how to weld TiAl alloys to steel components, especially stainless steel components, the inventors of the present invention propose to avoid introducing additional elements other than Ti, Al and Fe as much as possible when welding TiAl alloys to stainless steel structures, so as to avoid problems such as insufficient solid solution, complicated process and uneven distribution of elements in the joint, which are prone to segregation and brittle phases; to adopt welding methods with low cost, easy scale and industrialization as much as possible, to avoid deformation stress caused by excessive pre-machining, and to eliminate the stress that inevitably occurs in the processing process as much as possible in the processing process itself, so as to avoid applying additional processes.

[0009] According to one aspect of the present disclosure, a method for diffusion welding titanium aluminum alloy and stainless steel is provided, which comprises the following steps: Step 1: material preparation and surface treatment, grinding the end faces of the titanium aluminum alloy and the steel structure to be welded, then polishing until there are no scratches on the surface, using an organic solvent to ultrasonically clean the end faces and then drying; Step 2: placing the sample, placing the titanium aluminum alloy and the steel structure in a graphite mold in contact with each other, and then placing the graphite mold in a hot pressing sintering furnace; Step 3: heating operation, starting vacuum diffusion welding, heating to 450-650°C at a heating rate of 8-10°C / min and keeping warm for 30-40 min, then continue to heat up to 800-1000°C, and keep warm for 10-30min; step 4: heating and pressurizing operation, start pressurizing when the temperature reaches 800-1000°C, the rate is 1-5MPa / min, stop after 10-30min, the pressure is 20-50MPa, and continue to keep warm and pressurized for 20-80min; step 5: final treatment, the pressure drops naturally after stopping heating, and the surfaces of the obtained vacuum diffusion welded TiAl and steel components are polished and cleaned.

[0010] Preferably, in step 1, 80#, 120#, 280#, 400#, 800#, 1200# and 1500# sandpapers are used in sequence to grind the end faces to be welded of the titanium-aluminum alloy and the steel structure.

[0011] Preferably, in step 1, the organic solvent is various organic solvents, such as one or more of hydrocarbons, alkanes, fluorinated hydrocarbons, brominated hydrocarbons, alcohols, ethers, ketones, and gasoline. Preferably, the alcohol is one or more of C1 to C4 alcohols, particularly preferably ethanol (alcohol), the ketone is acetone, and the end surface ultrasonic cleaning lasts for 10 to 30 minutes, more preferably 15 minutes.

[0012] Preferably, in step 3, the temperature is increased to 500-600° C. at a heating rate of 8-10° C. / min and kept at that temperature for 30-40 min, and then the temperature is further increased to 850-950° C. at a heating rate of 8-10° C. / min and kept at that temperature for 10-25 min.

[0013] Preferably, in step 4, when the temperature reaches 850°C to 950°C, pressurization is started at a rate of 2 to 3 MPa / min, and is stopped after 10 to 25 minutes. The pressure is 30 to 50 MPa, and the temperature and pressure are maintained for 30 to 60 minutes.

[0014] Preferably, during the vacuum diffusion welding, the vacuum degree of the vacuum sintering furnace is ≤2×10 -2 Pa.

[0015] Preferably, the titanium aluminum alloy contains 40-50% Al and 8-9% Nb in atomic percentage, and the material of the steel structure is chromium silicon stainless steel. Further preferably, the titanium aluminum alloy contains 45% Al and 8.5% Nb in atomic percentage, and the grade of the chromium silicon stainless steel is 45Cr9Si3 stainless steel. Further preferably, the titanium aluminum alloy also includes 0-0.2% W, 0-0.2% B, and 0-0.02% Y in atomic percentage. Preferably, the titanium aluminum alloy also includes 0.2% W, 0.2% B, and 0.02% Y in atomic percentage.

[0016] Preferably, the titanium aluminum alloy is a titanium aluminum rod with a processing diameter of 10 to 50 mm, more preferably 30 mm; the steel structure is a steel rod with a processing diameter of 10 to 50 mm, more preferably 30 mm.

[0017] The present invention uses a vacuum hot pressing sintering furnace to perform diffusion bonding on titanium aluminum alloy and steel, so that the fresh surfaces of the materials on both sides are closely bonded, and a joint without obvious welding defects is obtained; the pressure and high temperature in the diffusion welding process are utilized to reasonably adjust the welding interface structure, reduce the brittle phase, and increase the solid solution phase, so that the joint obtained by the TiAl alloy has the advantages of small deformation, no stress concentration, few cracks, few brittle phases, high room temperature strength, etc., thereby realizing effective connection of the TiAl alloy and the stainless steel component, and improving the welding strength of the TiAl alloy and the stainless steel component. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other purposes, features and advantages of the present disclosure will become more apparent by describing the embodiments of the present disclosure in more detail in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the drawings, the same reference numerals generally represent the same components or steps.

[0019] Figure 1 A metallographic image showing a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and a stainless steel diffusion welded joint by diffusion welding according to Example 1 of the present disclosure, wherein the upper side is the titanium aluminum alloy and the lower side is the stainless steel; Figure 2 A SEM image showing a cross-section of a joint obtained by the method for manufacturing a titanium aluminum alloy and stainless steel diffusion welded joint by diffusion welding according to Example 1 of the present disclosure, wherein the upper side is the titanium aluminum alloy and the lower side is the stainless steel; Figure 3 A hardness distribution diagram of a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and a stainless steel diffusion welded joint by diffusion welding according to Example 1 of the present disclosure is shown, with the transition from the titanium aluminum alloy to the stainless steel from left to right; Figure 4A metallographic image showing a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and stainless steel diffusion welded joint by diffusion welding according to Example 2 of the present disclosure, wherein the upper side is titanium aluminum alloy and the lower side is stainless steel; Figure 5 A SEM image showing a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and stainless steel diffusion welded joint by diffusion welding according to Example 2 of the present disclosure, wherein the upper side is titanium aluminum alloy and the lower side is stainless steel; Figure 6 A hardness distribution diagram of a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and a stainless steel diffusion welded joint by diffusion welding according to Example 2 of the present disclosure is shown, with the transition from the titanium aluminum alloy to the stainless steel from left to right; Figure 7 A metallographic image showing a cross-section of a joint obtained by a method for manufacturing a diffusion welded joint of a titanium aluminum alloy and stainless steel by diffusion welding according to Example 3 of the present disclosure, wherein the upper side is the titanium aluminum alloy and the lower side is the stainless steel; Figure 8 A SEM image showing a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and stainless steel diffusion welded joint by diffusion welding according to Example 3 of the present disclosure, wherein the upper side is titanium aluminum alloy and the lower side is stainless steel; Fig. 9 A hardness distribution diagram of a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and stainless steel diffusion welded joint by diffusion welding according to Example 3 of the present disclosure is shown, with a transition from titanium aluminum to stainless steel from left to right.

[0020] Fig.10 A metallographic image showing a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and a stainless steel diffusion welded joint by diffusion welding according to Example 4 of the present disclosure, wherein the upper side is the titanium aluminum alloy and the lower side is the stainless steel; Fig.11 A SEM image showing a cross-section of a joint obtained by a method for manufacturing a diffusion welded joint of a titanium aluminum alloy and stainless steel by diffusion welding according to Example 4 of the present disclosure, wherein the upper side is the titanium aluminum alloy and the lower side is the stainless steel; Fig.12 A hardness distribution diagram of a cross-section of a joint obtained by a method for manufacturing a titanium aluminum alloy and stainless steel diffusion welded joint by diffusion welding according to Example 4 of the present disclosure is shown, with a transition from titanium aluminum to stainless steel from left to right. DETAILED DESCRIPTION

[0021] Below, the exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described here. Example Example 1

[0022] Step 1: Material preparation and surface treatment An ingot with an alloy composition of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y and a 45Cr9Si3 stainless steel ingot were respectively cut to obtain cylinders with a size of 50 mm in length and 30 mm in diameter, one end of each cylinder was selected as the end face to be welded, and the end faces to be welded of the titanium-aluminum alloy and the stainless steel cylinder were polished with 80#, 120#, 280#, 400#, 800#, 1200#, and 1500# sandpapers in sequence, and then polished until there were no scratches on the surface, and the end faces were ultrasonically cleaned with alcohol or acetone for 15 minutes and then dried; Step 2: The ground, polished, cleaned and dried titanium aluminum rod and stainless steel rod are placed in a graphite mold in contact with each other, and then the graphite mold is placed in a vacuum hot sintering furnace; Step 3: Heating Operation Start vacuum diffusion welding, heating rate is 10℃ / min, heating to 600℃ and keeping warm for 30min, then continue heating to 950℃ at 10℃ / min and keep warm for 10min; Step 4: Heating and Pressurizing Operation When the temperature reaches 950°C, the TiAl alloy rod and the stainless steel rod placed in the graphite die are axially pressed at a pressure rate of 3MPa / min, and the pressure is stopped after 10 minutes, reaching a pressure of 30MPa, and the pressure is maintained for 30 minutes, while the temperature remains unchanged; Step 5: Final processing After the heating is stopped, the pressure drops naturally, and the surfaces of the vacuum diffusion welded TiAl and steel components are polished and cleaned.

[0023] The obtained joint of the TiAl alloy and the stainless steel alloy was cut into a cross section by wire cutting, and the cross section was ground and polished, and the obtained metallographic photographs, SEM photographs and hardness distribution diagrams were respectively shown as follows: Figure 1 , 2 , as shown in Figure 3.

[0024] from Figure 1 It can be seen that the joint of the TiAl alloy and the stainless steel obtained by the present invention has no obvious shrinkage cavities, is tight, and has good bonding. Figure 2 It can be seen that the joint elements of the TiAl alloy obtained by the present invention and the stainless steel diffuse to form an intermediate phase layer with a small thickness and low hardness; Figure 3 The hardness distribution diagram of the cross section of the diffusion welded joint of titanium aluminum alloy and stainless steel. From left to right, it is the transition from titanium aluminum alloy to stainless steel. The hardness decreases in the middle, which is the hardness of the intermediate phase layer between TiAl alloy and steel. Figure 3It can be seen that the hardness distribution of the joint between the TiAl alloy and the stainless steel obtained in the present invention is uniform, and the hardness at the interface is lower than that of the pure TiAl or pure steel area, reaching about 350HV, which effectively reduces the hardness of the joint. Example 2

[0025] Step 1: Material preparation and surface treatment An ingot with alloy composition of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y and a 45Cr9Si3 stainless steel ingot were respectively cut to obtain cylinders with dimensions of 50 mm in length and 30 mm in diameter, one end of each cylinder was selected as the end face to be welded, and the end faces to be welded of the titanium-aluminum alloy and the stainless steel cylinder were polished with 80#, 120#, 280#, 400#, 800#, 1200#, and 1500# sandpapers in sequence, and then polished until there were no scratches on the surface, and the end faces were ultrasonically cleaned with alcohol or acetone for 15 minutes and then dried for 15; Step 2: The ground, polished, cleaned and dried titanium aluminum rod and stainless steel rod are placed in a graphite mold in contact with each other, and then the graphite mold is placed in a vacuum hot sintering furnace; Step 3: Heating Operation Start vacuum diffusion welding, heating rate is 8℃ / min, heating to 500℃ and keeping warm for 30min, then continue heating to 850℃ at 8℃ / min and keep warm for 25min; Step 4: Heating and Pressurizing Operation When the temperature reaches 850°C, the TiAl alloy rod and the stainless steel rod placed in the graphite die are axially pressurized at a pressurization rate of 2MPa / min, and the pressure is stopped after 25 minutes. When the pressure reaches 50MPa, the pressure is maintained for 60 minutes while the temperature is kept constant. Step 5: Final processing After the heating is stopped, the pressure drops naturally, and the surfaces of the vacuum diffusion welded TiAl and steel components are polished and cleaned.

[0026] The obtained joint of the TiAl alloy and the stainless steel alloy was cut into a cross section by wire cutting, and the cross section was ground and polished, and the obtained metallographic photographs, SEM photographs and hardness distribution diagrams were respectively shown as follows: Figure 4 , 5 , 6. From Figure 4 It can be seen that the joint of the TiAl alloy and the stainless steel obtained by the present invention has no obvious shrinkage cavities, is tight, and has good bonding; Figure 5 It can be seen that the joint elements of the TiAl alloy obtained by the present invention and the stainless steel diffuse to form an intermediate phase layer with a small thickness and low hardness; Figure 6The hardness distribution diagram of the cross section of the diffusion welded joint of titanium aluminum alloy and stainless steel. From left to right, it is the transition from titanium aluminum alloy to stainless steel. The hardness decreases in the middle, which is the hardness of the intermediate phase layer between TiAl alloy and steel. Figure 6 It can be seen that the hardness distribution of the joint between the TiAl alloy and the stainless steel obtained in the present invention is uniform, and the hardness at the interface is lower than that of the pure TiAl or pure steel area, reaching about 350HV, which effectively reduces the hardness of the joint. Example 3

[0027] Step 1: Material preparation and surface treatment An ingot with an alloy composition of Ti-45Al-9Nb and a 45Cr9Si3 stainless steel ingot are respectively cut to obtain a cylinder with a size of 50 mm in length and 30 mm in diameter, one end of each cylinder is selected as the end face to be welded, and the end faces to be welded of the titanium-aluminum alloy and the stainless steel cylinder are polished with 80#, 120#, 280#, 400#, 800#, 1200#, and 1500# sandpapers in sequence, and then polished until there are no scratches on the surface, and the end faces are ultrasonically cleaned with alcohol or acetone for 15 minutes and then dried; Step 2: The ground, polished, cleaned and dried titanium aluminum rod and stainless steel rod are placed in a graphite mold in contact with each other, and then the graphite mold is placed in a vacuum hot sintering furnace; Step 3: Heating Operation Start vacuum diffusion welding, heating rate is 10℃ / min, heating to 600℃ and keeping warm for 30min, then continue heating to 950℃ at 10℃ / min and keep warm for 10min; Step 4: Heating and Pressurizing Operation When the temperature reaches 950°C, the TiAl alloy rod and the stainless steel rod placed in the graphite die are axially pressed at a pressure rate of 3MPa / min, and the pressure is stopped after 10 minutes, reaching a pressure of 30MPa, and the pressure is maintained for 30 minutes, while the temperature remains unchanged; Step 5: Final processing After the heating is stopped, the pressure drops naturally, and the surfaces of the vacuum diffusion welded TiAl and steel components are polished and cleaned.

[0028] The obtained joint of the TiAl alloy and the stainless steel alloy was cut into a cross section by wire cutting, and the cross section was ground and polished, and the obtained metallographic photographs, SEM photographs and hardness distribution diagrams were respectively shown as follows: Figure 7 , 8 , 9. From Figure 7 It can be seen that the joint of the TiAl alloy and the stainless steel obtained by the present invention has no obvious shrinkage cavities, is tight, and has good bonding; Figure 8It can be seen that the joint elements of the TiAl alloy obtained by the present invention and the stainless steel diffuse to form an intermediate phase layer with a small thickness and low hardness; Fig. 9 The hardness distribution diagram of the cross section of the diffusion welded joint of titanium aluminum alloy and stainless steel. From left to right, it is the transition from titanium aluminum alloy to stainless steel. The hardness decreases in the middle, which is the hardness of the intermediate phase layer between TiAl alloy and steel. Fig. 9 It can be seen that the hardness distribution of the joint between the TiAl alloy and the stainless steel obtained in the present invention is uniform, and the hardness at the interface is lower than that of the pure TiAl or pure steel area, reaching about 350HV, which effectively reduces the hardness of the joint. Example 4

[0029] Step 1: Material preparation and surface treatment An ingot with an alloy composition of Ti-50Al-8Nb and a 45Cr9Si3 stainless steel ingot are respectively cut to obtain a cylinder with a size of 50 mm in length and 30 mm in diameter, one end of each cylinder is selected as the end face to be welded, and the end faces to be welded of the titanium-aluminum alloy and the stainless steel cylinder are polished with 80#, 120#, 280#, 400#, 800#, 1200#, and 1500# sandpapers in sequence, and then polished until there are no scratches on the surface, and the end faces are ultrasonically cleaned with alcohol or acetone for 15 minutes and then dried; Step 2: The ground, polished, cleaned and dried titanium aluminum rod and stainless steel rod are placed in a graphite mold in contact with each other, and then the graphite mold is placed in a vacuum hot sintering furnace; Step 3: Heating Operation Start vacuum diffusion welding, heating rate is 10℃ / min, heating to 600℃ and keeping warm for 30min, then continue heating to 950℃ at 10℃ / min and keep warm for 10min; Step 4: Heating and Pressurizing Operation When the temperature reaches 950°C, the TiAl alloy rod and the stainless steel rod placed in the graphite die are axially pressed at a pressure rate of 3MPa / min, and the pressure is stopped after 10 minutes, reaching a pressure of 30MPa, and the pressure is maintained for 30 minutes, while the temperature remains unchanged; Step 5: Final processing After the heating is stopped, the pressure drops naturally, and the surfaces of the vacuum diffusion welded TiAl and steel components are polished and cleaned.

[0030] The obtained joint of the TiAl alloy and the stainless steel alloy was cut into a cross section by wire cutting, and the cross section was ground and polished, and the obtained metallographic photographs, SEM photographs and hardness distribution diagrams were respectively shown as follows: Fig.10 , 11 , 12. From Fig.10It can be seen that the joint of the TiAl alloy and the stainless steel obtained by the present invention has no obvious shrinkage cavities, is tight, and has good bonding. Fig.11 It can be seen that the joint elements of the TiAl alloy obtained by the present invention and the stainless steel diffuse to form an intermediate phase layer with a small thickness and low hardness; Fig.12 The hardness distribution diagram of the cross section of the diffusion welded joint of titanium aluminum alloy and stainless steel. From left to right, it is the transition from titanium aluminum alloy to stainless steel. The hardness decreases in the middle, which is the hardness of the intermediate phase layer between TiAl alloy and steel. Fig.12 It can be seen that the hardness distribution of the joint between the TiAl alloy and the stainless steel obtained in the present invention is uniform, and the hardness at the interface is lower than that of the pure TiAl or pure steel area, reaching about 350HV, which effectively reduces the hardness of the joint.

[0031] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0032] The block diagrams of the devices, apparatuses, equipment, and systems involved in this disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including," "comprising," "having," and the like are open words, referring to "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or," and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0033] It should also be noted that in the apparatus, device and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0034] In this document, modifiers such as "first", "second", etc. without quantifiers are intended to distinguish different elements / components / circuits / modules / devices / steps, and are not used to emphasize the order, positional relationship, importance, priority, etc. In contrast, modifiers such as "first", "second", etc. with quantifiers can be used to emphasize the order, positional relationship, importance, priority, etc. of different elements / components / circuits / modules / devices / steps.

[0035] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0036] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for diffusion welding titanium aluminum alloy and stainless steel, characterized in that: The steps include: Step 1: material preparation and surface treatment, grinding the end faces of the titanium aluminum alloy and the steel structure to be welded, then polishing until there are no scratches on the surface, using an organic solvent to ultrasonically clean the end faces and then drying; Step 2: placing the sample, placing the titanium aluminum alloy and the steel structure in contact with each other in a graphite mold, and placing the graphite mold in a hot pressing sintering furnace; Step 3: Heating operation, start vacuum diffusion welding, heat up to 450-650℃ at a heating rate of 8-10℃ / min and keep warm for 30-40min, then continue to heat up to 800-1000℃ and keep warm for 10-30min; Step 4: heating and pressurizing operation, start pressurizing when the temperature reaches 800℃~1000℃, the rate is 1~5MPa / min, stop after 10~30min, the pressure is 20~50MPa, continue to keep warm and pressurized for 20~80min; Step 5: Final treatment: After stopping heating, the pressure naturally drops, and the surfaces of the vacuum diffusion welded TiAl and steel components are polished and cleaned.

2. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 1, characterized in that: In step 1, 80#, 120#, 280#, 400#, 800#, 1200#, and 1500# sandpapers are used in sequence to grind the end faces to be welded of the titanium aluminum alloy and the steel structure.

3. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 1, characterized in that: In step 1, the organic solvent is selected from one or more of hydrocarbons, alkanes, fluorinated hydrocarbons, brominated hydrocarbons, alcohols, ethers, ketones, and gasoline. The end surface ultrasonic cleaning lasts for 10 to 30 minutes.

4. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 1, characterized in that: In step 3, the temperature is raised to 500-600° C. at a heating rate of 8-10° C. / min and kept at that temperature for 30-40 min, and then the temperature is further raised to 850-950° C. at a heating rate of 8-10° C. / min and kept at that temperature for 10-25 min.

5. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 1, characterized in that: In step 4, when the temperature reaches 850°C to 950°C, pressurization is started at a rate of 2 to 3 MPa / min, and is stopped after 10 to 25 minutes. The pressure is 30 to 50 MPa, and the temperature and pressure are maintained for 30 to 60 minutes.

6. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 1, characterized in that: During the vacuum diffusion welding, the vacuum degree of the vacuum sintering furnace is ≤2×10 -2 Pa.

7. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 1, characterized in that: The titanium aluminum alloy contains 40-50% Al and 8-9% Nb in atomic percentage, and the material of the steel structure is chromium silicon stainless steel.

8. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 7, characterized in that: The titanium aluminum alloy contains 45% Al and 8.5% Nb in atomic percentage, and the chromium silicon stainless steel grade is 45Cr9Si3 stainless steel.

9. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 7, characterized in that: The titanium aluminum alloy further includes 0-0.2% W, 0-0.2% B, and 0-0.02% Y in atomic percentage.

10. The method for diffusion welding titanium aluminum alloy and stainless steel according to claim 7, characterized in that: The titanium aluminum alloy further includes 0.2% W, 0.2% B, and 0.02% Y in atomic percentage. The titanium-aluminum alloy is a titanium-aluminum alloy component with a processing diameter of 10 to 50 mm. The steel structure is a steel component with a processing diameter of 10 to 50 mm.

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