Method for improving interface quality of additive manufacturing gradient functional material

Abstract

The invention discloses a method for improving the interface quality of an additive manufacturing gradient functional material, and belongs to the field of advanced processing and preparation of metal materials. According to the method, firstly, the additive manufacturing gradient functional material is subjected to heat preservation for 1 h to 3 h in a heat treatment furnace under the condition of 400 DEG C to 1000 DEG C, then thermal deformation is conducted under the condition of the thermal deformation speed of 0.1 mm / s to 10 mm / s, and the deformation amount is 10% to 70%. The additive manufacturing gradient functional material is subjected to thermal deformation treatment, diffusion of alloy elements at the interface is promoted, the connection strength of chemical bonds at the interface is improved, the defects at the gradient interface are eliminated, the path of cracks in the expansion process is more zigzag, the deflection angle is increased, and the performance of the gradient functional material is improved. And the quality of the additive manufacturing gradient functional material interface is greatly improved.

Description

Technical Field

[0001] The invention relates to the field of advanced processing and preparation of metal materials, and specifically to a method for improving the interface quality of gradient functional materials in additive manufacturing. Background Art

[0002] Although advanced manufacturing technology for metal materials is constantly developing, most alloy components are mostly made of a single homogeneous material, manufactured using traditional subtractive processes, and assembled and combined through mechanical connections, with a single function. Due to this limitation, traditional alloy structures have a large number of parts, many separation surfaces, and redundant structural and functional systems, resulting in problems such as overweight structures, many fatigue weak parts and frequent cracking, long manufacturing cycles, and high manufacturing and assembly costs. As a typical non-uniform material, functional gradient materials have good designability. By changing the composition and microstructure of gradient materials, different functions can be achieved in different areas. These characteristics that traditional materials cannot match make gradient materials have important development and application prospects in the fields of aviation and aerospace.

[0003] Traditional methods for preparing functional gradient materials mainly include powder metallurgy and centrifugal casting. These methods are relatively mature and widely used in production, but they have practical problems such as high cost, long cycle, complex process, and difficulty in preparing parts with complex shapes and high forming precision, which restrict the application and development of functional gradient materials to a certain extent. Since additive manufacturing technology uses a discrete-stacking method to achieve near-net forming, by changing the alloy composition, process parameters and stacking path of the filler material during the layer-by-layer stacking process, components with gradient physical and chemical properties in one or more dimensions can be obtained. In recent years, the use of additive manufacturing methods to prepare alloy gradient materials has received more and more attention and has become a hot topic in the current research field of alloy gradient material preparation.

[0004] The existence of the gradient structure of additively manufactured gradient functional materials provides high strength while maintaining excellent ductility, solving the traditional conflict between strength and ductility, but there are still some problems. The physical properties of each layer in the gradient material, such as density, thermal expansion coefficient, melting point and laser absorptivity, are different, resulting in quality problems such as interface defects and poor bonding ability. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a method for improving the interface quality of gradient functional materials in additive manufacturing, reasonably arrange the alloy materials according to strength, stiffness, life and function, and improve the interface quality of gradient functional materials in additive manufacturing through thermal deformation technology, which is of great significance for realizing the composite integration, reasonable layout and uniform transition of different alloy materials, promoting the progress and development of national defense science and technology, and greatly improving the performance of weapons and equipment.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A method for improving the interface quality of a gradient functional material in additive manufacturing, comprising the following steps:

[0008] Step 1. Insulation before thermal deformation: Insulate the additively manufactured gradient functional material; wherein the insulation temperature is 400°C to 1000°C, and the insulation time is 1h to 3h. The specific insulation temperature and time are selected according to the type of additively manufactured gradient functional material and the interface quality;

[0009] Step 2. thermal deformation: thermally deforming the additively manufactured gradient functional material after heat preservation to obtain an alloy material with good gradient interface quality; wherein the thermal deformation speed is 0.1 mm / s-10 mm / s, and the deformation amount is 10% to 70%;

[0010] The functional gradient material is manufactured by an additive manufacturing method;

[0011] During the thermal deformation process, the additively manufactured functional gradient material does not produce surface cracks and folding defects.

[0012] During the failure process of the alloy material obtained after thermal deformation, the crack propagation path at the interface is more tortuous than that before thermal deformation, thereby improving the interface quality of the additively manufactured gradient functional material.

[0013] The design idea of ​​the present invention is:

[0014] The present invention firstly heats the additive manufacturing gradient functional material at 400℃~1000℃ for 1h-3h in a heat treatment furnace, and then performs heat deformation at a heat deformation rate of 0.1mm / s-10mm / s, with a deformation amount of 10%-70%. The present invention performs heat deformation treatment on the additive manufacturing gradient functional material, promotes the diffusion of alloy elements at the interface, increases the connection strength of chemical bonds at the interface, eliminates defects at the gradient interface, makes the crack path more tortuous and the deflection angle larger during the expansion process, and greatly improves the interface quality of the additive manufacturing gradient functional material. The method of the present invention can improve the interface quality of the additive manufacturing gradient functional material, promote the progress and development of national defense science and technology, and greatly improve the performance of weapons and equipment.

[0015] The advantages and beneficial effects of the present invention are:

[0016] The present invention is a method for improving the interface quality of additively manufactured gradient functional materials. The additively manufactured gradient functional materials are subjected to heat preservation treatment in the temperature range of 400°C to 1000°C using a heat treatment furnace, and then thermally deformed in a high temperature section of a two-phase region. This can eliminate defects at the interface of the additively manufactured gradient functional materials, promote the diffusion of alloy elements at the interface, increase the connection strength of chemical bonds at the interface, make the path of cracks in the expansion process more tortuous, and improve the interface quality of the additively manufactured gradient functional materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The microstructure at the alloy gradient interface prepared by powder feeding laser additive manufacturing in Example 1;

[0018] Figure 2 The microstructure at the gradient interface of the powder feeding laser additive alloy after thermal deformation treatment in Example 1;

[0019] Figure 3 The microstructure at the alloy gradient interface prepared by solid-state additive manufacturing in Example 2;

[0020] Figure 4 The microstructure at the gradient interface of the solid-state additive titanium alloy after thermal deformation treatment in Example 2;

[0021] Figure 5 The mechanical properties of the solid-state additive gradient functional material of Example 2 before and after thermal deformation treatment. DETAILED DESCRIPTION

[0022] The functional gradient material in the embodiment of the present invention is manufactured by additive manufacturing, including laser powder feeding additive manufacturing, laser powder spreading additive manufacturing, electron beam powder feeding additive manufacturing, electron beam powder spreading additive manufacturing, etc.

[0023] The present invention is further described in detail below through the accompanying drawings and embodiments.

[0024] Example 1

[0025] In this embodiment, a method for improving the interface quality of additively manufactured gradient functional materials is provided. Functional gradient materials are prepared by powder feeding laser additive manufacturing. When preparing the gradient functional materials prepared by powder feeding laser additive manufacturing, the sample model is first sliced ​​and layered at a certain thickness using layering and slicing software, and the three-dimensional shape information of the sample is converted into two-dimensional contour information. Then, under the control of the numerical control system, alloy powder materials of different brands are filled point by point on the alloy matrix according to a certain filling path. This process is repeated and layered to form a sample. The forming parameters of the sample are laser power 1800W, scanning speed 10mm / s, powder feeding rate 2.5g / min, and forming layer thickness 0.1mm. Then, the following steps are followed to improve the interface quality of the obtained additively manufactured gradient functional material:

[0026] Step 1. Place the gradient functional material prepared by powder feeding laser additive in a heat treatment furnace, heat it to 960°C, and keep it warm for 2 hours.

[0027] Step 2. The heat-insulated material is subjected to thermal deformation at a deformation speed of 10 mm / s with a deformation amount of 50%. After the thermal deformation, air cooling is adopted to finally obtain a powder-fed laser additive gradient functional material with good gradient interface quality.

[0028] The microstructure at the interface of the gradient functional material prepared by powder feeding laser additive manufacturing in the embodiment of the present invention is as follows: Figure 1 As shown. Figure 1 It can be seen that the gradient interface between alloy 1 and alloy 2 is obvious; the microstructure of the gradient interface of the powder feeding laser additive titanium alloy after thermal deformation treatment is as follows Figure 2 As shown, through Figure 2 It can be seen that the interface traces of the thermally deformed powder feeding laser additive gradient functional material in this embodiment disappear, a large number of short rod-shaped α phases appear, and the α phase has a tendency to spheroidize, which is consistent with the Figure 1 Compared with the microstructure at the interface in, the amount of secondary α phase and grain boundary increased, indicating that the diffusion of alloy elements at the interface is more sufficient and the interface quality is improved.

[0029] Example 2

[0030] This embodiment provides a method for improving the interface quality of a gradient functional material in additive manufacturing, and manufactures the functional gradient material by solid-state laser additive manufacturing.

[0031] Step 1. Place the functional gradient material prepared by solid-state laser additive manufacturing in a heat treatment furnace, heat it to 950°C, and keep it warm for 1.5 hours;

[0032] Step 2. The heat-insulated material is subjected to thermal deformation at a deformation speed of 5 mm / s, with a deformation amount of 20%. After thermal deformation, air cooling is used to finally obtain a solid-state laser additive gradient functional material with good gradient interface quality.

[0033] The microstructure of the gradient functional material interface prepared by solid-state additive manufacturing in this embodiment is as follows: Figure 3 As shown in the figure, the gradient interface between alloy 1 and alloy 2 is obvious; the microstructure of the gradient interface of solid-state additive titanium alloy after thermal deformation treatment is as follows Figure 4 As shown, from Figure 4 It can be seen that the interface traces of the solid-state additive gradient functional material in this embodiment disappear after thermal deformation, and the microstructure is composed of equiaxed α phase, newly generated secondary α phase and a small amount of β phase. Figure 3Compared with the microstructure at the interface, the amount of secondary α phase increases, the equiaxed α phase is broken, spheroidization and refinement are achieved, and the number of grain boundaries increases.

[0034] At the same time, the mechanical properties of the solid-state laser additive gradient functional material prepared in this embodiment before and after thermal deformation treatment were tested. The results are as follows: Figure 5 As shown in the figure, it can be clearly seen that the yield strength and tensile strength of the gradient interface of the solid additive alloy are improved after hot deformation treatment.

[0035] The above is only the best example of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for improving the interface quality of gradient functional materials in additive manufacturing, characterized in that: The specific steps include: Step 1. Insulation before thermal deformation: Insulate the additively manufactured gradient functional material at a temperature of 400°C to 1000°C for a time of 1h to 3h; Step 2. Thermal deformation: thermally deform the heat-insulated material to obtain an alloy material with good gradient interface quality.

2. A method for improving the interface quality of gradient functional materials in additive manufacturing according to claim 1, characterized in that: In step 1, the specific holding temperature and time are selected according to the type of gradient functional material for additive manufacturing and the interface quality.

3. A method for improving the interface quality of gradient functional materials in additive manufacturing according to claim 1, characterized in that: In step 2, the thermal deformation rate is 0.1 mm / s-10 mm / s.

4. A method for improving the interface quality of gradient functional materials in additive manufacturing according to claim 1, characterized in that: In step 2, during the thermal deformation process, the deformation amount is 10% to 70%.

5. A method for improving the interface quality of gradient functional materials in additive manufacturing according to claim 1, characterized in that: In step 2, during the thermal deformation process, the additively manufactured functional gradient material did not produce surface cracks and folding defects.

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