Laser Additive Manufacturing Titanium-Steel Multimaterial Components, Equipment and Methods for Improving Interface Bonding and Forming Performance by Suppressing Element Diffusion through an Intermediate Layer

Abstract

The present invention discloses a laser additive manufacturing titanium-steel multi-material component, its equipment and method for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer. The laser additive manufacturing titanium-steel multi-material component includes a titanium alloy layer, an intermediate layer, and a stainless steel layer. The intermediate layer includes a single-element metal Ce layer and a single-element metal Cr layer; the titanium alloy layer, the single-element metal Ce layer, the single-element metal Cr layer, and the stainless steel layer are all sequentially deposited by a laser directed energy deposition process. It can be seen that, for the intermediate layer of the present invention, by designing the single-element metal Ce layer and the single-element metal Cr layer, the diffusion of Ti element in the titanium alloy layer and Fe element in the stainless steel layer is blocked through the mutual solubility characteristics of Ce and Cr, and good metallurgical bonding between different materials is achieved, solving the problems such as interface cracking and holes caused by brittle intermetallic compounds when titanium alloy and stainless steel are directly connected.

Description

Technical Field

[0001] The present invention relates to a laser additive manufacturing titanium-steel multi-material component, its equipment and method for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer, and belongs to the technical field of metal laser additive manufacturing. Background Art

[0002] Traditional technical methods can manufacture multi-material components with simple geometric structures, but cannot manufacture components with complex structures and multifunctional characteristics. The multi-material laser additive manufacturing technology provides a new way for preparing components with specific physical properties, can achieve good metallurgical bonding of multiple materials, and can also prepare complex structural components. In the past decade or so, laser additive manufacturing has been widely studied and used in manufacturing technology due to its inherent flexibility and high efficiency in producing complex components. Traditional laser additive manufacturing is limited to one material. Therefore, it is impossible to ensure that the component has properties such as wear resistance, high temperature resistance, and corrosion resistance while meeting the requirements of strength and low cost. The emerging multi-material laser additive manufacturing technology can overcome the above problems.

[0003] Laser directed energy deposition is an advanced additive manufacturing technology that can directly manufacture high-density and functional components. During the manufacturing process, a laser beam is focused on a substrate to form a molten pool, and a powder stream is continuously input into the molten pool and melted through a delivery system, and finally printed into shape. Because of its advantages such as small heat affected zone and fine solidification structure, it is beneficial to prepare multi-material components. Titanium alloys have the advantages of light weight, high strength, corrosion resistance, and biocompatibility, and stainless steels have the advantages of high strength, corrosion resistance, easy processing, and low cost. Therefore, achieving good metallurgical bonding between titanium alloys and stainless steels is of great significance for industrial development. However, due to the different metallurgical and thermophysical properties of the two materials, they cannot be mixed and melted. When directly connecting the two materials, many brittle Ti-Fe intermetallic compounds will be generated, resulting in defects such as interface cracking and pores, which often reduce the interface bonding strength and severely limit their industrial applications. Summary of the Invention

[0004] The object of the present invention is to provide a laser additive manufacturing titanium-steel multi-material component, its equipment and method for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer. By setting an intermediate layer capable of blocking the diffusion of Ti and Fe elements between the titanium alloy layer and the stainless steel layer, it is possible to effectively avoid harmful brittle cracking caused by the mismatch of atomic structure and thermal expansion coefficient, and then obtain a titanium-steel multi-material component with good metallurgical bonding at the interface and excellent properties.

[0005] To achieve the above technical object, the present invention will adopt the following technical solutions:

[0006] A laser additive manufacturing titanium-steel multi-material component, comprising a titanium alloy layer, an intermediate layer, and a stainless steel layer. The intermediate layer includes a single-element metal Ce layer and a single-element metal Cr layer. The titanium alloy layer, the single-element metal Ce layer, the single-element metal Cr layer, and the stainless steel layer are all deposited from bottom to top in sequence by laser directed energy deposition process.

[0007] Preferably, the titanium alloy layer is formed by laser sintering and melting titanium alloy powder, the single-element metal Ce layer is formed by laser sintering and melting single-element metal Ce powder, the single-element metal Cr layer is formed by laser sintering and melting single-element metal Cr powder, and the stainless steel layer is formed by laser sintering and melting stainless steel powder.

[0008] Preferably, the number of layers of both the single-element metal Ce layer and the single-element metal Cr layer is two.

[0009] Preferably, the titanium alloy powder is TC4 powder, the particle size of TC4 powder is 53 - 150 μm, and in the TC4 powder, the Al content is 6.75 wt.%, the V content is 4.5 wt.%, and the rest is Ti;

[0010] The stainless steel powder is SS316 powder, the particle size of SS316 powder is 53 - 150 μm, and in the SS316 powder, the Cr content is 18.0 wt.%, the Ni content is 10.0 wt.%, the Mo content is 2.5 wt.%, and the rest is Fe.

[0011] Another technical object of the present invention is to provide a titanium-steel multi-material laser additive manufacturing device for suppressing element diffusion through an intermediate layer to improve interface bonding and forming performance. It is built based on the laser directed energy deposition process and is used for laser additive manufacturing of titanium-steel multi-material components, including a protection cavity, a powder feeder, a printing head, a forming substrate, and a controller. The printing head is integrated with a powder delivery tube, a laser, and a shielding gas delivery tube; the forming substrate is placed in the protection cavity, the powder feeder contains the powder to be printed, and the printing powder contained in the powder feeder can be delivered to the printing area on the forming substrate through the powder delivery tube; the laser beam spot emitted by the laser can fall on the printing area on the forming substrate; the shielding gas can be delivered to the printing area on the forming substrate through the shielding gas delivery tube; the forming substrate is a titanium alloy substrate; the powder feeder contains four kinds of printing powders, corresponding to titanium alloy powder, single-element metal Ce powder, single-element metal Cr powder, and stainless steel powder;

[0012] The controller creates a powder processing file based on the structural characteristics of the titanium-steel multi-material component; four powder processing data are integrated in the powder processing file, and each powder processing data is configured with laser printing process parameters and corresponding laser scanning path planning;

[0013] Four powder processing data correspond to the first to fourth powder processing data, where: the first powder processing data is used to deposit and melt titanium alloy powder to form a titanium alloy layer; the second powder processing data is used to deposit and melt elemental metal Ce powder to form an elemental metal Ce layer; the third powder processing data is used to deposit and melt elemental metal Cr powder to form an elemental metal Cr layer; the fourth powder processing data is used to deposit and melt stainless steel powder to form a stainless steel layer;

[0014] Under the control of the controller, after controlling the laser power and scanning speed of the laser beam output by the laser according to the laser printing process parameters in the first powder processing data, start the powder delivery pipe to transport the titanium alloy powder contained in the powder feeder to the printing area, and then control the movement of the working head according to the laser scanning path planning in the first powder processing data until the deposition of the titanium alloy layer on the titanium alloy substrate is completed; switch the type of powder transported by the powder delivery pipe so that the powder delivery pipe transports the elemental metal Ce powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the second powder processing data until the deposition of the elemental metal Ce layer with a preset number of layers on the titanium alloy layer is completed; switch the type of powder transported by the powder delivery pipe so that the powder delivery pipe transports the elemental metal Cr powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the third powder processing data until the deposition of the elemental metal Cr layer with a preset number of layers on the elemental metal Ce layer is completed; switch the type of powder transported by the powder delivery pipe so that the powder delivery pipe transports the stainless steel powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the fourth powder processing data until the deposition of the stainless steel layer on the elemental metal Cr layer is completed, and a titanium-steel multi-material component can be obtained.

[0015] Another technical object of the present invention is to provide a method for improving the interface bonding and forming performance by suppressing element diffusion through an intermediate layer in titanium-steel multi-material laser additive manufacturing, which is realized based on the above-mentioned titanium-steel multi-material laser additive manufacturing equipment for improving the interface bonding and forming performance by suppressing element diffusion through an intermediate layer. After cleaning the titanium alloy substrate, a laser directed energy deposition process is adopted, and by controlling the powder feeding rate, defocus amount, overlap rate, and protective gas flow rate, a titanium alloy layer, an elemental metal Ce layer, an elemental metal Cr layer, and a stainless steel layer are sequentially deposited on the surface of the titanium alloy substrate, thereby obtaining a titanium-steel multi-material component with good metallurgical bonding at the interface and excellent performance. The specific steps are as follows:

[0016] Step 1: Powder drying:

[0017] Titanium alloy powder, elemental metal Ce powder, elemental metal Cr powder, and stainless steel powder were dried in a vacuum drying oven at 80°C for 10 h to remove moisture and improve powder fluidity. After drying, they were placed in a powder feeder.

[0018] Step 2: Create powder processing data:

[0019] Based on the laser directed energy deposition process, four independent powder processing data sets are created, each of which is configured with laser printing process parameters and laser scanning path planning;

[0020] The four sets of powder processing data correspond to the first to fourth powder processing data, where:

[0021] The first powder processing data is used to deposit melted titanium alloy powder to form a titanium alloy layer;

[0022] The second powder processing data is used to deposit and melt the elemental metal Ce powder to form an elemental metal Ce layer;

[0023] The third powder processing data is used to deposit and melt the elemental metal Cr powder to form an elemental metal Cr layer;

[0024] The fourth powder processing data is used to deposit the melted stainless steel powder to form a stainless steel layer;

[0025] Step 3: Place the titanium alloy substrate into the protective chamber, control the industrial robot to adjust the defocus, close the door of the protective chamber after adjustment, and introduce pure argon gas for deoxygenation;

[0026] Step 4: After the oxygen content in the protected cavity drops to 50 ppm, start the laser to sequentially deposit different materials on the titanium alloy substrate to obtain a titanium-steel multi-material component with a good metallurgical bond at the interface. The specific steps include:

[0027] Step 4.1, loading the first powder processing data in step 2 to first deposit a titanium alloy layer on the titanium alloy substrate;

[0028] Step 4.2: After the titanium alloy layer is deposited, the defocus amount is adjusted based on the top surface of the titanium alloy layer, and the second powder processing data in step 2 is loaded to deposit a single metal Ce layer on the surface of the titanium alloy layer;

[0029] Step 4.3: After the deposition of the elemental metal Ce layer is completed, the defocus amount is adjusted based on the top surface of the elemental metal Ce layer, and the third powder processing data in step 2 is loaded to deposit an elemental metal Cr layer on the surface of the elemental metal Ce layer;

[0030] Step 4.4: After the deposition of the single-element metal Cr layer is completed, adjust the defocus amount based on the top surface of the single-element metal Cr layer, and load the fourth powder processing data in Step 2 to deposit a stainless steel layer on the surface of the single-element metal Cr layer, and finally obtain a titanium-steel multi-material component with good metallurgical bonding at the interface.

[0031] Preferably, the powder feeding rate is 10 g / min, the defocus amount is 2 - 3 mm, the overlapping rate is 50%, and the protective gas flow rate is 14 - 16 L / min.

[0032] Preferably, the particle size of the TC4 powder is 53 - 150 μm, and in the TC4 powder, the Al content is 6.75 wt.%, the V content is 4.5 wt.%, and the rest is Ti; the particle size of the SS316 powder is 53 - 150 μm, and in the SS316 powder, the Cr content is 18.0 wt.%, the Ni content is 10.0 wt.%, the Mo content is 2.5 wt.%, and the rest is Fe;

[0033] The particle size of the single-element metal Ce powder is 20 - 130 μm, and the particle size of the single-element metal Cr powder is 20 - 130 μm.

[0034] Preferably, in the first powder processing data, the laser power is 700 W and the scanning speed is 10 mm / s;

[0035] In the second powder processing data, the laser power is 700 W and the scanning speed is 10 mm / s;

[0036] In the third powder processing data, the laser power is 900 W and the scanning speed is 10 mm / s;

[0037] In the fourth powder processing data, the laser power is 1000 W and the scanning speed is 8 mm / s.

[0038] Preferably, after the titanium alloy layer is deposited on the titanium alloy substrate, repeat Step 4.2 to deposit more than two layers of single-element metal Ce layers on the titanium alloy layer; after the deposition of the single-element metal Ce layer is completed, repeat Step 4.3 to deposit more than two layers of single-element metal Cr layers on the single-element metal Ce layer.

[0039] Based on the above technical objectives, compared with the prior art, the present invention has the following advantages:

[0040] 1. The laser additive manufacturing titanium-steel multi-material component that suppresses element diffusion through an intermediate layer to improve interface bonding and forming performance. A single-element metal Ce layer and a single-element metal Cr layer are sequentially deposited between the titanium alloy layer and the stainless steel layer, thereby effectively blocking the diffusion of Ti and Fe elements, and finally preparing a titanium-steel multi-material component with a stainless steel layer and a titanium alloy layer as the outer layers. Thus, it can be seen that the titanium-steel multi-material component described in the present invention can simultaneously possess the advantages of both titanium alloy and stainless steel materials (usually, titanium alloy has advantages such as high specific strength, good heat and low temperature resistance, and good impact resistance, while stainless steel has excellent mechanical properties, good corrosion resistance, and low cost). On the other hand, by utilizing the mutual solubility of Ce and Cr, a single-element metal Ce layer and a single-element metal Cr layer are sequentially deposited between the titanium alloy layer and the stainless steel layer, which can effectively block Ti and Fe elements. At the same time, the single-element metal Ce can improve the corrosion resistance and oxidation resistance of the titanium alloy material, and the single-element metal Cr can achieve good metallurgical bonding with the stainless steel material. Therefore, the present invention realizes good metallurgical bonding of titanium and steel multi-materials under the action of the intermediate layer, and solves the problems such as interface cracking and pores caused by brittle intermetallic compounds when titanium alloy and stainless steel are directly connected.

[0041] 2. The present invention uses laser directed energy deposition technology to prepare multi-material components, which can possess the advantages of different materials, such as local heat resistance, corrosion resistance, high thermal conductivity, wear resistance, etc. It can also precisely control the material distribution, and can print specific materials at designated positions with a unique structure to achieve specific functions, and achieve more excellent comprehensive performance.

[0042] 3. The multi-material additive manufacturing technology can better adapt to different working conditions with its unique structure design and material distribution, especially under harsh working conditions that require multi-function and multi-environment adaptability. Therefore, it provides a new option for the development of fields such as aerospace, nuclear industry, medical treatment, and automobile manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic structural diagram of depositing a titanium-steel multi-material component by the titanium-steel multi-material laser additive manufacturing equipment described in the present invention;

[0044] In the figure: 1 - laser; 2 - powder delivery tube; 3 - protective gas delivery tube; 4 - substrate; 51 - titanium alloy layer; 52 - intermediate layer; 53 - stainless steel layer;

[0045] Figure 2 It is a schematic diagram of the laser scanning strategy of the present invention;

[0046] Figure 3 It is an OM image of the Cr and SS316 interfaces of the titanium-steel multi-material component described in Example 3 of the present invention;

[0047] Figure 4 OM image of the Cr, SS316 interface of the titanium-steel multi-material component described in Embodiment 4 of the present invention;

[0048] Figure 5 OM image of the Cr, SS316 interface of the titanium-steel multi-material component described in Embodiment 5 of the present invention;

[0049] Figure 6 Macrograph of the direct connection of laser directed energy deposition TC4 titanium alloy and SS316 stainless steel according to the present invention. Detailed implementation manners

[0050] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Unless otherwise specifically stated, the relative arrangements, expressions, and numerical values of the components and steps described in these embodiments do not limit the scope of the present invention. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0051] Titanium alloys have advantages such as high specific strength, good heat and low temperature resistance, and good impact resistance. Stainless steels have excellent mechanical properties, good corrosion resistance, and low cost. If stainless steel and titanium alloy can be effectively connected, the advantages of both materials can be combined at the same time. However, due to the large differences in physical properties (such as thermal expansion coefficient, thermal conductivity, etc.) between titanium alloys and stainless steels, a large number of brittle intermetallic compounds will be generated at their interfaces when directly connecting the two materials, and residual stresses and a large amount of strain will be generated, resulting in connection failure. Figure 6 The macrograph of the direct connection of laser directed energy deposition TC4 titanium alloy and SS316 stainless steel is disclosed. It can be observed that many cracks appear on the surface of SS316, and the quality of the interfacial metallurgical bonding is very poor. Eventually, the SS316 part falls off during wire cutting, indicating that a large number of brittle intermetallic compounds are generated between the stainless steel and the titanium alloy, resulting in connection failure.

[0052] In order to achieve an effective connection between stainless steel and titanium alloy, the present invention introduces elemental metal Ce and elemental metal Cr. By utilizing the mutual solubility characteristics between elemental metal Ce and elemental metal Cr, it can effectively block Ti and Fe elements, and achieve good metallurgical bonding between stainless steel and titanium alloy, thus solving the problems such as interface cracking and holes caused by brittle intermetallic compounds when directly connecting titanium alloy and stainless steel.

[0053] Therefore, the present invention discloses a laser additive manufacturing titanium-steel multi-material component, as well as an apparatus and a method for laser additive manufacturing of titanium-steel multi-material components. The technical solutions involved in the present invention will be described in detail below in conjunction with each embodiment. Embodiment

[0054] This embodiment discloses a laser additive manufacturing titanium-steel multi-material component, which includes a titanium alloy layer 51, an intermediate layer 52, and a stainless steel layer 53. The intermediate layer 52 includes an elemental metal Ce layer and an elemental metal Cr layer. The titanium alloy layer 51, the elemental metal Ce layer, the elemental metal Cr layer, and the stainless steel layer 53 are all deposited from bottom to top in sequence by the laser directed energy deposition process. Among them: The titanium alloy layer 51 is formed by laser sintering and melting titanium alloy powder. The titanium alloy powder can be TC4 powder. The particle size of the TC4 powder is 53 - 150 μm. In the TC4 powder, the Al content is 6.75 wt.%, the V content is 4.5 wt.%, and the rest is Ti. Of course, other existing types of titanium alloy powders can also be selected for the titanium alloy powder. The elemental metal Ce layer is formed by laser sintering and melting elemental metal Ce powder. The particle size of the elemental metal Ce powder is 20 - 130 μm. The elemental metal Cr layer is formed by laser sintering and melting elemental metal Cr powder. The particle size of the elemental metal Cr powder is 20 - 130 μm. And the stainless steel layer 53 is formed by laser sintering and melting stainless steel powder. The stainless steel powder can be selected as SS316 powder. The particle size of the SS316 powder is 53 - 150 μm. In the SS316 powder, the Cr content is 18.0 wt.%, the Ni content is 10.0 wt.%, the Mo content is 2.5 wt.%, and the rest is Fe. Of course, other existing types of stainless steel powders can also be selected for the stainless steel powder.

[0055] The number of layers of the elemental metal Ce layer and the elemental metal Cr layer can be determined according to actual needs. Through testing, it is found that when the number of layers of both the elemental metal Ce layer and the elemental metal Cr layer is 2, the interface metallurgical bonding of the titanium-steel multi-material component is good, with only some small holes and basically no defects, indicating that using 2 layers of the elemental metal Ce layer and 2 layers of the elemental metal Cr layer can effectively inhibit the diffusion of Ti and Fe elements, avoid the formation of brittle intermetallic compounds, reduce stress, and avoid the generation and propagation of cracks, thus achieving the purpose of improving the comprehensive mechanical properties. Embodiment

[0056] This embodiment discloses a titanium-steel multi-material laser additive manufacturing device that improves interface bonding and forming performance by suppressing element diffusion through an intermediate layer. It is built based on the laser directed energy deposition process and is used for laser additive manufacturing of the titanium-steel multi-material component described in Example 1. Under the action of a focused laser beam, the printing powder flows into the molten pool and melts. Through the preferred intermediate layer 52, crack-free connection can be basically achieved between the titanium alloy and the stainless steel, and it has excellent mechanical properties.

[0057] As Figure 1 shown, the titanium-steel multi-material laser additive manufacturing device described in this embodiment includes a protection cavity, a powder feeder, a printing head, a forming substrate, and a controller. The printing head is integrated with a powder delivery tube 2, a laser 1, and a shielding gas delivery tube 3. The forming substrate is placed in the protection cavity. The powder feeder contains the printing powder to be printed, and the printing powder contained in the powder feeder can be delivered to the printing area on the forming substrate through the powder delivery tube 2. The laser beam spot emitted by the laser 1 can fall on the printing area on the forming substrate. The shielding gas can be delivered to the printing area on the forming substrate through the shielding gas delivery tube 3. The forming substrate is a titanium alloy substrate. The powder feeder contains four kinds of printing powders, corresponding to titanium alloy powder, elemental metal Ce powder, elemental metal Cr powder, and stainless steel powder.

[0058] The controller creates a powder processing file based on the structural characteristics of the titanium-steel multi-material component. The powder processing file integrates four powder processing data, and each powder processing data is configured with laser printing process parameters and corresponding laser scanning path planning. The laser printing process parameters include laser power and scanning speed. The laser scanning path planning adopts a reciprocating scanning strategy. Referring to Appendix Figure 2 , the initial point of laser melting is different for each layer, and each layer rotates 90°, which can ensure uniform heating of the specimen and a flat surface.

[0059] The four powder processing data correspond to the first to fourth powder processing data, where: the first powder processing data is used to deposit and melt titanium alloy powder to form a titanium alloy layer 51; the second powder processing data is used to deposit and melt elemental metal Ce powder to form an elemental metal Ce layer; the third powder processing data is used to deposit and melt elemental metal Cr powder to form an elemental metal Cr layer; the fourth powder processing data is used to deposit and melt stainless steel powder to form a stainless steel layer 53.

[0060] Under the control of the controller, after controlling the laser power and scanning speed of the laser beam output by the laser 1 according to the laser printing process parameters in the first powder processing data, start the powder delivery pipe 2 to deliver the titanium alloy powder contained in the powder feeder to the printing area, and then control the movement of the working head according to the laser scanning path planning in the first powder processing data until the deposition of the titanium alloy layer 51 on the titanium alloy substrate is completed; switch the type of powder delivered by the powder delivery pipe 2 so that the powder delivery pipe 2 delivers the elemental metal Ce powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the second powder processing data until the deposition of the elemental metal Ce layer with a preset number of layers on the titanium alloy layer 51 is completed; switch the type of powder delivered by the powder delivery pipe 2 so that the powder delivery pipe 2 delivers the elemental metal Cr powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the third powder processing data until the deposition of the elemental metal Cr layer with a preset number of layers on the elemental metal Ce layer is completed; switch the type of powder delivered by the powder delivery pipe 2 so that the powder delivery pipe 2 delivers the stainless steel powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the fourth powder processing data until the deposition of the stainless steel layer 53 on the elemental metal Cr layer is completed, and a titanium-steel multi-material component can be obtained. Example

[0061] This example discloses a method for improving the interface bonding and forming performance by suppressing element diffusion through an intermediate layer in titanium-steel multi-material laser additive manufacturing, which is realized based on the above-mentioned titanium-steel multi-material laser additive manufacturing equipment for improving the interface bonding and forming performance by suppressing element diffusion through an intermediate layer. After cleaning the titanium alloy substrate, the laser directed energy deposition process is adopted, and by controlling the powder feeding rate, defocus amount, overlapping rate, and protective gas flow rate, a titanium alloy layer 51, an elemental metal Ce layer, an elemental metal Cr layer, and a stainless steel layer 53 are sequentially deposited on the surface of the titanium alloy substrate, thereby obtaining a titanium-steel multi-material component with good metallurgical bonding at the interface and excellent performance. Among them: the powder feeding rate is 10 g / min, the defocus amount is 2 - 3 mm, the overlapping rate is 50%, and the protective gas flow rate is 14 - 16 L / min.

[0062] Specifically, the method for improving the interface bonding and forming performance by suppressing element diffusion through an intermediate layer in the titanium-steel multi-material laser additive manufacturing described in this example includes the following steps:

[0063] Step 1. Powder drying:

[0064] Put the titanium alloy powder, elemental metal Ce powder, elemental metal Cr powder, and stainless steel powder in a vacuum drying oven and dry them at 80 °C for 10 h to remove moisture and improve the powder fluidity. After drying, place them in a powder feeder; the powder feeding rate of the powder feeder is 10 g / min;

[0065] Step Two: Create powder processing data:

[0066] Based on the laser directed energy deposition process, create four independent powder processing data. Each powder processing data is configured with laser printing process parameters and laser scanning path planning; then use a controller to integrate the above four powder processing data into a powder processing file to control the deposition of the corresponding printed powder layer by layer;

[0067] The four powder processing data correspond to the first to fourth powder processing data, where:

[0068] The first powder processing data is used to deposit and melt the titanium alloy powder to form a titanium alloy layer 51;

[0069] The second powder processing data is used to deposit and melt the elemental metal Ce powder to form an elemental metal Ce layer;

[0070] The third powder processing data is used to deposit and melt the elemental metal Cr powder to form an elemental metal Cr layer;

[0071] The fourth powder processing data is used to deposit and melt the stainless steel powder to form a stainless steel layer 53;

[0072] Step Three: After cleaning the titanium alloy substrate, place it in a protective cavity. Then, use an industrial robot to adjust the defocus amount of the working head. The defocus amount is 2 - 3 mm. After adjustment, close the chamber door and introduce pure argon for deoxidation. The protective gas flow rate is 14 - 16 L / min;

[0073] Step Four: After the oxygen content in the protective cavity drops to 50 ppm, start the laser 1 to sequentially deposit different materials on the titanium alloy substrate to obtain a titanium - steel multi - material component with good metallurgical bonding at the interface. The specific steps are as follows:

[0074] Step 4.1: Load the first powder processing data in Step Two to deposit the titanium alloy layer 51 on the titanium alloy substrate first;

[0075] After the deposition of the titanium alloy layer 51 is completed, adjust the defocus amount based on the top surface of the titanium alloy layer 51, and load the second powder processing data in Step Two to deposit the elemental metal Ce layer on the surface of the titanium alloy layer 51;

[0076] Step 4.3: After the deposition of the elemental metal Ce layer, adjust the defocus amount based on the top surface of the elemental metal Ce layer, and load the third powder processing data in Step 2 to deposit an elemental metal Cr layer on the surface of the elemental metal Ce layer;

[0077] Step 4.4: After the deposition of the elemental metal Cr layer, adjust the defocus amount based on the top surface of the elemental metal Cr layer, and load the fourth powder processing data in Step 2 to deposit a stainless steel layer 53 on the surface of the elemental metal Cr layer, and finally obtain a titanium-steel multi-material component with good metallurgical bonding at the interface.

[0078] Step Five: After preparation, cut the specimen from the substrate by wire electrical discharge machining, put it into an oil stain cleaning agent for ultrasonic cleaning to remove surface stains, and then polish and grind the titanium-steel multi-material specimen according to the standard metallographic preparation method, and observe the interface under an optical microscope. Example

[0079] The difference between this example and Example 3 is as follows:

[0080] In Step One, the titanium alloy powder is TC4 powder, the particle size of the TC4 powder is 53 - 150 μm, and in the TC4 powder, the Al content is 6.75 wt.%, the V content is 4.5 wt.%, and the rest is Ti; the stainless steel powder is SS316 powder, the particle size of the SS316 powder is 53 - 150 μm, and in the SS316 powder, the Cr content is 18.0 wt.%, the Ni content is 10.0 wt.%, the Mo content is 2.5 wt.%, and the rest is Fe. The particle size of the elemental metal Ce powder is 20 - 130 μm, and the particle size of the elemental metal Cr powder is 20 - 130 μm.

[0081] In Step 4, Step 4.1 is repeatedly implemented to continuously deposit 4 layers of titanium alloy layers 51 on the titanium alloy substrate. The laser process parameters for depositing the titanium alloy layer 51 are: laser power 700 W, scanning speed 10 mm / s; after the deposition of 4 layers of titanium alloy layers 51 is completed, based on the surface of the uppermost titanium alloy layer 51, Step 4.2 is repeatedly implemented to continuously deposit 2 layers of elemental metal Ce layers on the titanium alloy layer 51. The laser process parameters for depositing the elemental metal Ce layer are: laser power 700 W, scanning speed 10 mm / s; after the deposition of 2 layers of elemental metal Ce layers is completed, based on the surface of the uppermost elemental metal Ce layer, Step 4.3 is repeatedly implemented to deposit 2 layers of elemental metal Cr layers on the elemental metal Ce layer. The laser process parameters for depositing the elemental metal Cr layer are: laser power 900 W, scanning speed 10 mm / s; after the deposition of 2 layers of elemental metal Cr layers is completed, based on the surface of the uppermost elemental metal Cr layer, Step 4.4 is implemented to deposit 2 layers of stainless steel layers 53 on the elemental metal Cr layer, finally forming a titanium-steel multi-material component with good metallurgical bonding at the interface and excellent properties. The laser process parameters for depositing the stainless steel layer 53 are: laser power 1000 W, scanning speed 8 mm / s.

[0082] In the titanium-steel multi-material component prepared in this embodiment, the average thickness of the 2 layers of elemental metal Ce layers is 1.06 mm, and the average thickness of the 2 layers of elemental metal Cr layers is 1.05 mm.

[0083] After preparation, the specimen is cut from the substrate by wire electrical discharge machining, placed in an oil stain cleaning agent and ultrasonically cleaned to remove surface stains, and then the titanium-steel multi-material specimen is polished and ground according to the standard metallographic preparation method, and the interface is observed under an optical microscope as Figure 3 shown.

[0084] By observing Figure 3 the interface optical image of the titanium-steel multi-material component shown, it can be seen that the metallurgical bonding at the interface is good, there are only some small holes, and there are basically no defects, indicating that the use of 2 intermediate layers 52 can effectively inhibit the diffusion of Ti and Fe elements, avoid the formation of brittle intermetallic compounds, reduce stress, avoid the generation and propagation of cracks, so as to achieve the purpose of improving the comprehensive mechanical properties. Example

[0085] The difference between this embodiment and Example 4 is that both the elemental metal Ce layer and the elemental metal Cr layer are 1 layer. The titanium-steel multi-material component obtained is polished and ground according to the standard metallographic preparation method, and the interface is observed under an optical microscope as Figure 4 shown.

[0086] In the titanium-steel multi-material component prepared in this example, the average thickness of the single-layer elemental metal Ce layer is 0.45 mm, and the average thickness of the single-layer elemental metal Cr layer is 0.5 mm.

[0087] Comparing the OM pictures of Comparative Example 4 and Example 5, it can be seen that vertical cracks and holes appear in the titanium-steel multi-material component prepared in this example. This shows that when the intermediate barrier layer (1 single-layer elemental metal Ce layer and 1 single-layer elemental metal Cr layer) is relatively thin, the effect of the barrier element is limited, and brittle intermetallic compounds are generated at the interface, which will greatly reduce the comprehensive mechanical properties of the titanium-steel multi-material. Example

[0088] The difference between this example and Example 4 is that both the single-layer elemental metal Ce layer and the single-layer elemental metal Cr layer are 3 layers. The titanium-steel multi-material component prepared is polished according to the standard metallographic preparation method, and the interface is observed under an optical microscope as Figure 5 shown.

[0089] In the titanium-steel multi-material component prepared in this example, the average thickness of the 3 single-layer elemental metal Ce layers is 1.2 mm, and the average thickness of the 3 single-layer elemental metal Cr layers is 1.5 mm.

[0090] Comparing the OM pictures of Example 4 and Example 6, it can be seen that large holes appear in the intermediate barrier layer of the titanium-steel multi-material component prepared in this example. This shows that when the thickness of the intermediate barrier layer is too large, the defects will also increase. Therefore, when connecting multi-materials, the thickness of the intermediate barrier layer should be controlled well, which can not only control the defects but also improve the comprehensive mechanical properties of the titanium-steel multi-material.

[0091] Comprehensively comparing Examples 4-6, it can be seen that for specific powder materials (TC4 titanium alloy powder, SS316 stainless steel powder), under the control of specific laser power, scanning speed, and defocus amount, a single-layer elemental metal Ce layer and a single-layer elemental metal Cr layer with a thickness of 1-1.2 mm are sequentially formed between the titanium alloy layer 51 and the stainless steel layer 53, which can effectively achieve the effective barrier of Ti and Fe elements between the titanium alloy layer 51 and the stainless steel layer 53, thereby obtaining a titanium-steel multi-material component with good interface bonding and excellent properties. In fact, for different powder materials and different process conditions (laser power, scanning speed, defocus amount), the thickness of the intermediate barrier layer is variable, but the overall control goal is to achieve the effective barrier of Ti and Fe elements.

[0092] Comparative Example

[0093] This comparative example provides a method for fabricating a titanium-steel multi-material component using laser directed energy deposition. After melting and depositing TC4 titanium alloy powder on a titanium alloy substrate to form a titanium alloy layer 51, SS316 stainless steel powder is directly melted and deposited on the titanium alloy layer 51. The specific steps are as follows:

[0094] (1) Take appropriate amounts of TC4 and SS316 powders, place them in a vacuum drying oven at 80 °C for 10 h to remove moisture and improve powder fluidity. After drying, place them in a powder feeder;

[0095] (2) Start the industrial robot (i.e., the above-mentioned controller), and program and plan the laser power, scanning speed, and scanning path for different materials, specifically divided into two processing data files for TC4 and SS316;

[0096] (3) Start the powder feeder, water chiller, laser 1, and oxygen content detector in sequence. After cleaning the titanium alloy substrate, place it in the protection cavity. Then, control the industrial robot to adjust the defocus amount. After adjustment, close the chamber door and introduce 99.9% pure argon gas. When the oxygen content drops below 50 ppm, start printing;

[0097] (4) First, deposit 4 layers of TC4 on the titanium alloy substrate with a laser power of 700 W and a scanning speed of 10 mm / s. Then, based on the surface of TC4, deposit 2 layers of SSз16 with a laser power of 1000 W and a scanning speed of 8 mm / s. Finally, the printing is completed. The macroscopic image is as shown in Figure 6 shown. It can be observed that many cracks appear on the surface of SS316, and the quality of the interfacial metallurgical bonding is very poor. Finally, the SS316 part falls off during wire cutting, indicating that a large amount of brittle intermetallic compounds are formed between stainless steel and titanium alloy without the barrier element of the intermediate layer 52, resulting in connection failure.

Claims

1. A laser additive manufacturing titanium-steel multi-material component that improves interface bonding and forming performance by suppressing element diffusion through an intermediate layer, comprising a titanium alloy layer, an intermediate layer, and a stainless steel layer, characterized in that The middle layer includes a single-element metal Ce layer and a single-element metal Cr layer; the titanium alloy layer, the single-element metal Ce layer, the single-element metal Cr layer, and the stainless steel layer are sequentially deposited from bottom to top by laser directed energy deposition process; the number of layers of both the single-element metal Ce layer and the single-element metal Cr layer is two.

2. The laser additive manufacturing titanium-steel multi-material component for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer according to claim 1, wherein The titanium alloy layer is formed by laser sintering and melting titanium alloy powder, the single-element metal Ce layer is formed by laser sintering and melting single-element metal Ce powder, the single-element metal Cr layer is formed by laser sintering and melting single-element metal Cr powder, and the stainless steel layer is formed by laser sintering and melting stainless steel powder.

3. The laser additive manufacturing titanium-steel multi-material component for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer according to claim 2, characterized in that, The titanium alloy powder is TC4 powder, the particle size of TC4 powder is 53 - 150 μm, and in the TC4 powder, the Al content is 6.75 wt.%, the V content is 4.5 wt.%, and the rest is Ti; The stainless steel powder is SS316 powder, the particle size of SS316 powder is 53 - 150 μm, and in the SS316 powder, the Cr content is 18.0 wt.%, the Ni content is 10.0 wt.%, the Mo content is 2.5 wt.%, and the rest is Fe.

4. A titanium-steel multi-material laser additive manufacturing device that suppresses element diffusion through an intermediate layer to improve interface bonding and forming performance, built based on the laser directed energy deposition process, and used for laser additive manufacturing of titanium-steel multi-material components, including a protective cavity, a powder feeder, a printing head, a forming substrate, and a controller. The printing head is integrated with a powder delivery tube, a laser, and a shielding gas delivery tube; the forming substrate is placed in the protective cavity, the powder feeder contains the powder to be printed, and the printing powder contained in the powder feeder can be transported through the powder delivery tube to the printing area on the forming substrate; the laser beam spot emitted by the laser can fall on the printing area on the forming substrate; the shielding gas can be transported through the shielding gas delivery tube to the printing area on the forming substrate; it is characterized in that, The forming substrate is a titanium alloy substrate; the powder feeder contains four kinds of printing powders, corresponding to titanium alloy powder, single-element metal Ce powder, single-element metal Cr powder, and stainless steel powder; The controller creates a powder processing file based on the structural characteristics of the titanium-steel multi-material component; four powder processing data are integrated in the powder processing file, and each powder processing data is configured with laser printing process parameters and corresponding laser scanning path planning; The four powder processing data correspond to the first to fourth powder processing data, where: the first powder processing data is used to deposit and melt titanium alloy powder to form a titanium alloy layer; the second powder processing data is used to deposit and melt single-element metal Ce powder to form a single-element metal Ce layer; the third powder processing data is used to deposit and melt single-element metal Cr powder to form a single-element metal Cr layer; the fourth powder processing data is used to deposit and melt stainless steel powder to form a stainless steel layer; Under the control of the controller, after controlling the laser power and scanning speed of the laser beam output by the laser according to the laser printing process parameters in the first powder processing data, start the powder delivery pipe to deliver the titanium alloy powder contained in the powder feeder to the printing area, and then control the movement of the working head according to the laser scanning path planning in the first powder processing data until the deposition of the titanium alloy layer on the titanium alloy substrate is completed; switch the type of powder delivered by the powder delivery pipe so that the powder delivery pipe delivers the elemental metal Ce powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the second powder processing data until the deposition of two layers of elemental metal Ce layers on the titanium alloy layer is completed; switch the type of powder delivered by the powder delivery pipe so that the powder delivery pipe delivers the elemental metal Cr powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the third powder processing data until the deposition of two layers of elemental metal Cr layers on the elemental metal Ce layer is completed; switch the type of powder delivered by the powder delivery pipe so that the powder delivery pipe delivers the stainless steel powder contained in the powder feeder to the printing area, and control the movement of the working head according to the laser scanning path planning in the fourth powder processing data until the deposition of the stainless steel layer on the elemental metal Cr layer is completed, and a titanium-steel multi-material component can be obtained.

5. A method for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer in titanium-steel multi-material laser additive manufacturing, which is realized based on the titanium-steel multi-material laser additive manufacturing equipment for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer as described in claim 4, characterized in that, After cleaning the titanium alloy substrate, adopt the laser directed energy deposition process, and by controlling the powder feeding rate, defocus amount, overlap rate, and protective gas flow rate, deposit a titanium alloy layer, an elemental metal Ce layer, an elemental metal Cr layer, and a stainless steel layer on the surface of the titanium alloy substrate in sequence, thereby manufacturing a titanium-steel multi-material component with good metallurgical bonding at the interface and excellent properties. The specific steps are as follows: Step 1. Powder drying: Place the titanium alloy powder, elemental metal Ce powder, elemental metal Cr powder, and stainless steel powder in a vacuum drying oven respectively and dry them at 80 °C for 10 h to remove moisture and improve the powder fluidity. After drying, place them into the powder feeder. Step 2. Create powder processing data: Based on the laser directed energy deposition process, create four independent powder processing data, and each powder processing data is configured with laser printing process parameters and laser scanning path planning. The four powder processing data correspond to the first to fourth powder processing data, where: The first powder processing data is used to deposit and melt the titanium alloy powder to form a titanium alloy layer; The second powder processing data is used to deposit and melt the elemental metal Ce powder to form an elemental metal Ce layer; The third powder processing data is used to deposit and melt the elemental metal Cr powder to form an elemental metal Cr layer; The fourth powder processing data is used to deposit and melt the stainless steel powder to form a stainless steel layer; Step 3. Place the titanium alloy substrate into the protection cavity, control the industrial robot to adjust the defocus amount. After adjustment, close the hatch of the protection cavity and introduce pure argon gas for deoxidation. Step 4. After the oxygen content in the cavity to be protected drops to 50 ppm, start the laser to sequentially deposit different materials on the titanium alloy substrate to obtain a titanium-steel multi-material component with good metallurgical bonding at the interface, specifically including the following steps: Step 4.

1. Load the first powder processing data in Step 2 to deposit a titanium alloy layer on the titanium alloy substrate first; Step 4.

2. After the deposition of the titanium alloy layer is completed, adjust the defocus amount based on the top surface of the titanium alloy layer, and load the second powder processing data in Step 2 to deposit two layers of elemental metal Ce layers on the surface of the titanium alloy layer; Step 4.

3. After the deposition of the elemental metal Ce layer is completed, adjust the defocus amount based on the top surface of the elemental metal Ce layer, and load the third powder processing data in Step 2 to deposit two layers of elemental metal Cr layers on the surface of the elemental metal Ce layer; Step 4.

4. After the deposition of the elemental metal Cr layer is completed, adjust the defocus amount based on the top surface of the elemental metal Cr layer, and load the fourth powder processing data in Step 2 to deposit a stainless steel layer on the surface of the elemental metal Cr layer, and finally obtain a titanium-steel multi-material component with good metallurgical bonding at the interface.

6. The method for improving interface bonding and forming properties by suppressing element diffusion through an intermediate layer in titanium-steel multi-material laser additive manufacturing according to claim 5, characterized in that, The powder feeding rate is 10 g / min, the defocus amount is 2 - 3 mm, the overlapping rate is 50%, and the protective gas flow rate is 14 - 16 L / min.

7. The method for suppressing element diffusion through an intermediate layer to improve interface bonding and forming performance in titanium-steel multi-material laser additive manufacturing according to claim 5, characterized in that, The particle size of the TC4 powder is 53 - 150 μm, and in the TC4 powder, the Al content is 6.75 wt.%, the V content is 4.5 wt.%, and the rest is Ti; the particle size of the SS316 powder is 53 - 150 μm, and in the SS316 powder, the Cr content is 18.0 wt.%, the Ni content is 10.0 wt.%, the Mo content is 2.5 wt.%, and the rest is Fe; The particle size of the elemental metal Ce powder is 20 - 130 μm, and the particle size of the elemental metal Cr powder is 20 - 130 μm.

8. The method for improving interface bonding and forming performance by suppressing element diffusion through an intermediate layer in titanium-steel multi-material laser additive manufacturing according to claim 5, wherein, In the first powder processing data, the laser power is 700 W and the scanning speed is 10 mm / s; In the second powder processing data, the laser power is 700 W and the scanning speed is 10 mm / s; In the third powder processing data, the laser power is 900 W and the scanning speed is 10 mm / s; In the fourth powder processing data, the laser power is 1000 W and the scanning speed is 8 mm / s.

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