Additive manufacturing gradient alloy and preparation method thereof

Abstract

The invention belongs to the technical field of metal material additive manufacturing, and particularly relates to an additive manufacturing gradient alloy and a preparation method thereof.The alloy comprises an alloy matrix, a transition layer and a cladding layer, the transition layer is located between the alloy matrix and the cladding layer, the transition layer is deposited on the alloy matrix, and the cladding layer is deposited on the transition layer; and the transition layer is formed by mixing alloy matrix powder and cladding layer powder. According to the method, nucleation growth of printing cracks can be remarkably inhibited, so that no crack exists in the cladding layer, no unfused hole exists at the interface of the cladding layer and the matrix, and the bonding effect of the cladding layer is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing of metal materials, and particularly relates to an additive manufacturing gradient alloy and a preparation method thereof. Background Art

[0002] Some equipment in the nuclear industry has complex structures and harsh operating environments, and has extremely high requirements for the mechanical properties and corrosion resistance of component materials. Especially for some imported foreign equipment, the spare parts procurement cycle is long, the procurement cost is high, and once damaged, the shutdown and repair cycle is long, which will cause great economic losses. Additive manufacturing (also known as 3D printing) technology is a rapid prototyping technology that has emerged in recent years. It has the advantages of realizing integrated net forming of complex structures, short manufacturing cycle, high material utilization rate, and excellent product performance. Especially in the aspect of component repair, it can not only optimize the product design scheme, improve the equipment manufacturing quality, reduce the spare parts procurement cost, but also quickly and efficiently solve the problem of on-site emergency spare parts supply, and optimize the spare parts inventory structure, with great market application value.

[0003] Nickel-based superalloys are preferred repair materials for equipment components in the aerospace and nuclear industry fields due to their good oxidation and ablation resistance, excellent manufacturing process performance, good plasticity, and high temperature strength. Laser additive manufacturing technology has characteristics such as high energy density, rapid cooling, and multiple thermal cycles. Therefore, there are problems such as complex types of manufacturing defects, difficult control of defect content, and uneven stress distribution in additive manufacturing alloys. Although domestic and foreign researchers have carried out some basic research on printing process technologies, there are still micro and macro crack defects, and mechanical properties are lower than expected. Among them, how to improve the stress distribution of the repair layer and reduce the residual stress is the key bottleneck problem of metal additive manufacturing repair technology. Summary of the Invention

[0004] The purpose of the present invention is to provide an additive manufacturing gradient alloy and a preparation method thereof. Based on the design of the transition layer and by optimizing the laser cladding parameters, the nucleation and growth of printing cracks can be significantly inhibited, so that there are no cracks in the cladding layer, no unfused pores at the interface between the cladding layer and the substrate, and the bonding effect of the cladding layer is improved.

[0005] The technical solution for achieving the purpose of the present invention: An additive manufacturing gradient alloy includes an alloy substrate, a transition layer, and a cladding layer. The transition layer is located between the alloy substrate and the cladding layer, the transition layer is deposited on the alloy substrate, the cladding layer is deposited on the transition layer, and the transition layer is composed of a mixture of alloy substrate powder and cladding layer powder.

[0006] The alloy substrate is at least one of 17-4 PH stainless steel, 316L stainless steel, 15-5 PH stainless steel, and 18-8 stainless steel.

[0007] The cladding layer is at least one of Incoloy 800 alloy, Hastelloy C276 alloy, Inconel 600 alloy, Monel 400 alloy and Stellite 6 alloy.

[0008] The mass proportions of the alloy matrix powder and the cladding layer powder in the transition layer are as follows: the alloy matrix powder accounts for 10%-90%, and the cladding layer powder accounts for 10%-90%.

[0009] The number of layers of the transition layer is at least one of 1 layer, 2 layers, 3 layers, and 4 layers.

[0010] A method for preparing a gradient alloy by additive manufacturing, comprising: Step S1, preparing alloy matrix powder and cladding layer powder, screening through a sieve to obtain alloy matrix powder and cladding layer powder; placing the screened alloy matrix powder and cladding layer powder into a dryer for drying; Step S2, fully mixing the alloy matrix powder and the cladding layer powder obtained by drying in step S1 according to the mass ratio to obtain a mixed powder; Step S3: using a laser cladding process, depositing the mixed powder obtained in step S2 on the surface of the alloy substrate to form a transition layer, and depositing cladding layer powder on the surface of the transition layer to form a cladding layer; finally forming a gradient alloy.

[0011] The sieve in step S1 is 300-500 mesh.

[0012] In step S1, the drying temperature is 60° C.-80° C., and the drying time is 18 h-30 h.

[0013] In the step S2, the mass proportions of the alloy matrix powder and the cladding layer powder are respectively: the alloy matrix powder accounts for 10%-90%, and the cladding layer powder accounts for 10%-90%.

[0014] The process parameters for forming the transition layer by laser cladding process in step S3 are as follows: laser power of 800-3200 W, scanning speed of 5-25 mm / s, spot diameter of 3-5 mm, powder feeding rate of 0.5-2.5 r / min, and overlap rate of 30%-80%; the process parameters for forming the cladding layer by laser cladding process are as follows: laser power of 800-3200 W, scanning speed of 5-25 mm / s, spot diameter of 3-5 mm, powder feeding rate of 0.5-2.5 r / min, and overlap rate of 30%-80%.

[0015] The beneficial technical effects of the present invention are: The present invention prepares a high-quality gradient alloy cladding layer by depositing an intermediate layer between the alloy substrate and the cladding layer and setting specific laser cladding parameters, so that there are no cracks in the cladding layer and no unfused pores at the interface between the cladding layer and the substrate, thereby achieving performance improvement. Description of the Drawings

[0016] Figure 1 The following are optical microscope images of the macroscopic morphologies of the cladding layers of Example 1 and Comparative Examples 1-5: Figure 1 In (a) is the macroscopic morphology diagram of the cladding layer of Example 1, Figure 1 In (b) is the macroscopic morphology diagram of the cladding layer of Comparative Example 1, Figure 1 In (c) is the macroscopic morphology diagram of the cladding layer of Comparative Example 2, Figure 1 In (d) is the macroscopic morphology diagram of the cladding layer of Comparative Example 3, Figure 1 In (e) is the macroscopic morphology diagram of the cladding layer of Comparative Example 4, Figure 1 In (f) is the macroscopic morphology diagram of the cladding layer of Comparative Example 5; Figure 2 It is the microstructure diagram of the alloy of Example 1; Figure 2 In it, 1 - alloy substrate layer; 2 - intermediate layer; 3 - cladding layer. Detailed Description of the Invention

[0017] The present invention will be further described in detail below with reference to the drawings and examples.

[0018] An additive manufacturing gradient alloy provided by the present invention includes an alloy substrate, an intermediate layer, and a cladding layer. The intermediate layer is located between the alloy substrate and the cladding layer. The intermediate layer is deposited on the alloy substrate, and the cladding layer is deposited on the intermediate layer. The intermediate layer is composed of a mixture of alloy substrate powder and cladding layer powder.

[0019] The alloy substrate is at least one of 17-4 PH stainless steel, 316L stainless steel, 15-5 PH stainless steel, and 18-8 stainless steel. Further, the alloy substrate is any one of 17-4 PH stainless steel, 316L stainless steel, 15-5 PH stainless steel, and 18-8 stainless steel. Preferably, the alloy substrate is 15-5 PH stainless steel.

[0020] The cladding layer is at least one of Incoloy 800 alloy, Hastelloy C276 alloy, Inconel 600 alloy, Monel 400 alloy, and Stellite 6 alloy. Further, the cladding layer is any one of Incoloy 800 alloy, Hastelloy C276 alloy, Inconel 600 alloy, Monel 400 alloy, and Stellite 6 alloy. Preferably, the cladding layer is Stellite 6 alloy.

[0021] The mass percentages of the alloy matrix powder and the cladding layer powder in the transition layer are respectively: the proportion of the alloy matrix powder is 10%-90%, and the proportion of the cladding layer powder is 10%-90%. Further, the proportion of the alloy matrix powder is any one or the range between any two of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%; the proportion of the cladding layer powder is any one or the range between any two of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%.

[0022] In a specific embodiment, by mass percentage, the transition layer is composed of a mixture of 50% cladding layer powder + 50% alloy matrix powder, 10% cladding layer powder + 90% alloy matrix powder, 20% cladding layer powder + 80% alloy matrix powder, 30% cladding layer powder + 70% alloy matrix powder, 40% cladding layer powder + 60% alloy matrix powder, 60% cladding layer powder + 40% alloy matrix powder, 70% cladding layer powder + 30% alloy matrix powder, 80% cladding layer powder + 20% alloy matrix powder, or 90% cladding layer powder + 10% alloy matrix powder.

[0023] The number of layers of the transition layer is at least one of 1 layer, 2 layers, 3 layers, and 4 layers.

[0024] When the number of layers of the transition layer is multiple (i.e., 2 layers, 3 layers, or 4 layers), the mass percentages of the cladding layer powder and the alloy matrix powder in each layer of the transition layer gradually decrease in the direction of the alloy matrix powder and gradually increase in the direction of the cladding layer powder from the alloy matrix to the cladding layer. For example: When the number of layers of the transition layer is 2 layers, in the direction from the alloy matrix to the cladding layer, transition layers with mass percentages of 40% cladding layer powder + 60% alloy matrix powder and 60% cladding layer powder + 40% alloy matrix powder are successively used; When the number of layers of the transition layer is 3 layers, in the direction from the alloy matrix to the cladding layer, transition layers with mass percentages of 30% cladding layer powder + 70% alloy matrix powder, 50% cladding layer powder + 50% alloy matrix powder, and 70% cladding layer powder + 30% alloy matrix powder are successively used.

[0025] When the number of layers of the transition layer is multiple, each layer of the transition layer is successively deposited from the surface of the alloy matrix until the last layer of the transition layer is deposited, and then the cladding layer is deposited.

[0026] In a specific embodiment, the microstructure of 15-5 PH stainless steel is martensite, and the microstructure of Stellite 6 alloy is austenite.

[0027] A method for preparing an additive manufacturing gradient alloy provided by the present invention includes the following steps: Step S1, preparing alloy matrix powder and cladding layer powder, screening through a sieve to obtain alloy matrix powder and cladding layer powder, the sieve is 300 mesh-500 mesh; placing the screened alloy matrix powder and cladding layer powder into a dryer for drying; the drying temperature is 60°C-80°C, and the drying time is 18h-30h; Step S2, fully mixing the alloy matrix powder and the cladding layer powder obtained by drying in step S1 according to the mass ratio to obtain a mixed powder; the mass ratios of the alloy matrix powder and the cladding layer powder are: the alloy matrix powder accounts for 10%-90%, and the cladding layer powder accounts for 10%-90%; Step S3, using a laser cladding process, depositing the mixed powder obtained in step S2 on the surface of the alloy substrate to form a transition layer, and depositing cladding layer powder on the surface of the transition layer to form a cladding layer; finally forming a gradient alloy; The process parameters for forming the transition layer by laser cladding deposition are as follows: laser power 800-3200 W, scanning speed 5-25 mm / s, spot diameter 3-5 mm, powder feeding rate 0.5-2.5 r / min, overlap rate 30%-80%; The process parameters for depositing the cladding layer using the laser cladding process are: laser power of 800-3200 W, scanning speed of 5-25 mm / s, spot diameter of 3-5 mm, powder feeding rate of 0.5-2.5 r / min, and overlap rate of 30%-80%.

[0028] The thickness of the deposited transition layer is 490um-510um; the thickness of the deposited cladding layer is 780um-800um.

[0029] Example 1 A method for preparing a gradient alloy by additive manufacturing, comprising: Step S1, the alloy matrix powder is 15-5 PH stainless steel, and the cladding layer powder is Stellite 6 alloy. 15-5 PH stainless steel powder and Stellite 6 alloy powder are prepared, and 15-5 PH stainless steel powder and Stellite 6 alloy powder are obtained by screening through a 500-mesh sieve; the screened 15-5 PH stainless steel powder and Stellite 6 alloy powder are placed in a dryer and dried at 65° C. for 24 hours; Step S2, the 15-5 PH stainless steel powder and the Stellite 6 alloy powder obtained by drying in step S1 are fully mixed in a mass ratio of 1:1 (50% of 15-5 PH stainless steel powder + 50% of Stellite 6 alloy powder) to obtain a mixed powder; Step S3: Using the laser cladding process, deposit the mixed powder obtained in step S2 on the surface of the alloy substrate to form a transition layer, and deposit 100% of the Stellite 6 alloy powder obtained by drying in step S1 on the surface of the transition layer to form a cladding layer; finally, a gradient alloy is formed. The process parameters for depositing the transition layer by the laser cladding process are the same as those for depositing the cladding layer, which are: laser power 2000 W, scanning speed 10 mm / s, overlapping rate 50%, spot diameter 4 mm, and powder feeding rate 1 r / min.

[0030] The macroscopic morphology diagram of the cladding layer prepared by the above method is as shown in Figure 1 (a) in Figure 2 . The microscopic structure diagram of the alloy prepared by the above method is as shown in

[0031] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 has no transition layer, and the cladding layer is directly deposited on the alloy substrate.

[0032] The cladding layer of Comparative Example 1 is 100% Stellite 6 alloy, and the laser cladding process parameters for alloy preparation are the same as those in Example 1.

[0033] The macroscopic morphology diagram of the cladding layer of Comparative Example 1 is as shown in Figure 1 (b) in

[0034] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 has no transition layer, the cladding layer is directly deposited on the alloy substrate, and the laser power in the laser cladding process for alloy preparation.

[0035] The cladding layer of Comparative Example 2 is 100% Stellite 6 alloy, the laser power is 1700 W, and other laser cladding process parameters are the same as those in Example 1.

[0036] The macroscopic morphology diagram of the cladding layer of Comparative Example 2 is as shown in Figure 1 (c) in

[0037] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 has no transition layer, the cladding layer is directly deposited on the alloy substrate, and the laser power in the laser cladding process for alloy preparation.

[0038] The cladding layer of Comparative Example 3 is 100% Stellite 6 alloy, the laser power is 1400 W, and other laser cladding process parameters are the same as those in Example 1.

[0039] The macroscopic morphology diagram of the cladding layer of Comparative Example 3 is as shown in Figure 1 (d) in

[0040] Comparative Example 4 The difference between Comparative Example 4 and Example 1 lies in that Comparative Example 4 has no transition layer, and the cladding layer is directly deposited on the alloy substrate. The laser power in the laser cladding process for alloy preparation.

[0041] The cladding layer of Comparative Example 4 is 100% Stellite 6 alloy, the laser power is 2300 W, and other laser cladding process parameters are the same as those of Example 1.

[0042] The macroscopic morphology diagram of the cladding layer of Comparative Example 4 is as shown in Figure 1 (e) in.

[0043] Comparative Example 5 The difference between Comparative Example 5 and Example 1 lies in that Comparative Example 5 has no transition layer, and the cladding layer is directly deposited on the alloy substrate. The laser power in the laser cladding process for alloy preparation.

[0044] The cladding layer of Comparative Example 5 is 100% Stellite 6 alloy, the laser power is 2600 W, and other laser cladding process parameters are the same as those of Example 1.

[0045] The macroscopic morphology diagram of the cladding layer of Comparative Example 5 is as shown in Figure 1 (f) in.

[0046] Obviously, from Figure 1 It can be seen that there are no cracks in the cladding layer of Example 1; obvious cracking occurred in Comparative Examples 1-5, and the cracks penetrated through the superalloy cladding layer. It can be seen from this that in the case of no transition layer, obvious cracking occurred in the cladding layer.

[0047] From Figure 2 It can be seen that the internal structures of the transition layer and the cladding layer of the alloy prepared in Example 1 are both columnar dendrites, the layer interface is well bonded, there are no cracks, and the nucleation and growth of cracks during the laser cladding process are effectively inhibited.

[0048] The transition layer of the gradient alloy of the present invention is composed of the cladding layer powder and the alloy substrate powder. Because it has the same alloying elements as the adjacent layers (alloy substrate and cladding layer), the element interdiffusion during the additive manufacturing process can effectively improve the interlayer bonding ability; the optimized laser cladding process parameters can effectively avoid the hot cracks caused by excessive heat input and the unfused pores induced by insufficient heat input, which play a decisive role in the preparation of crack-resistant laser cladding gradient superalloys.

[0049] In summary, based on the transition layer design, the gradient alloy of the present invention can significantly inhibit the nucleation and growth of printing cracks and improve the bonding effect of the cladding layer by optimizing the laser cladding parameters, thereby achieving performance improvement.

[0050] The present invention has been described in detail with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art. The content not described in detail in the present invention can all adopt the prior art.

Claims

1. An additively manufactured gradient alloy, characterized in that: It includes an alloy substrate, a transition layer and a cladding layer. The transition layer is located between the alloy substrate and the cladding layer. The transition layer is deposited on the alloy substrate. The cladding layer is deposited on the transition layer. The transition layer is composed of a mixture of alloy substrate powder and cladding layer powder.

2. The additive manufacturing gradient alloy according to claim 1, characterized in that: The alloy matrix is ​​at least one of 17-4PH stainless steel, 316L stainless steel, 15-5 PH stainless steel, and 18-8 stainless steel.

3. The additive manufacturing gradient alloy according to claim 1, characterized in that: The cladding layer is at least one of Incoloy 800 alloy, Hastelloy C276 alloy, Inconel 600 alloy, Monel 400 alloy and Stellite 6 alloy.

4. The additive manufacturing gradient alloy according to claim 1, characterized in that: The mass proportions of the alloy matrix powder and the cladding layer powder in the transition layer are as follows: the alloy matrix powder accounts for 10%-90%, and the cladding layer powder accounts for 10%-90%.

5. The additive manufacturing gradient alloy according to claim 1, characterized in that: The number of layers of the transition layer is at least one of 1 layer, 2 layers, 3 layers, and 4 layers.

6. The additive manufacturing gradient alloy according to claim 5, characterized in that: When the number of transition layers is multiple, the mass ratio of the cladding layer powder to the alloy matrix powder in each transition layer gradually decreases from the alloy matrix to the cladding layer, and the mass ratio of the cladding layer powder gradually increases.

7. A method for preparing a gradient alloy by additive manufacturing, characterized in that: include: Step S1, preparing alloy matrix powder and cladding layer powder, screening through a sieve to obtain alloy matrix powder and cladding layer powder; placing the screened alloy matrix powder and cladding layer powder into a dryer for drying; Step S2, fully mixing the alloy matrix powder and the cladding layer powder obtained by drying in step S1 according to the mass ratio to obtain a mixed powder; Step S3: using a laser cladding process, depositing the mixed powder obtained in step S2 on the surface of the alloy substrate to form a transition layer, and depositing cladding layer powder on the surface of the transition layer to form a cladding layer; finally forming a gradient alloy.

8. The method for preparing a gradient alloy by additive manufacturing according to claim 7, characterized in that: The sieve in step S1 is 300-500 mesh.

9. The method for preparing a gradient alloy by additive manufacturing according to claim 7, characterized in that: In step S1, the drying temperature is 60° C.-80° C., and the drying time is 18 h-30 h.

10. The method for preparing a gradient alloy by additive manufacturing according to claim 7, characterized in that: The process parameters for forming the transition layer by laser cladding process in step S3 are as follows: laser power of 800-3200 W, scanning speed of 5-25 mm / s, spot diameter of 3-5 mm, powder feeding rate of 0.5-2.5 r / min, and overlap rate of 30%-80%; the process parameters for forming the cladding layer by laser cladding process are as follows: laser power of 800-3200 W, scanning speed of 5-25 mm / s, spot diameter of 3-5 mm, powder feeding rate of 0.5-2.5 r / min, and overlap rate of 30%-80%.

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