Material component adjustable and controllable additive manufacturing process based on laser powder bed melting

Abstract

The invention relates to a material component adjustable and controllable additive manufacturing process based on laser powder bed melting, which comprises the following steps: S1, determining a component gradient path of a printing material from a workpiece matrix area to a strengthening area according to a preset workpiece three-dimensional model; s2, after matrix powder is laid layer by layer according to the component gradient path in the S1, a carbon nanoparticle solution is sprayed in a strengthening area; s3, carrying out L-PBF treatment in the matrix area by adopting a high scanning speed and a low power parameter, and carrying out L-PBF treatment in the strengthening area by adopting a low scanning speed and high power, so that the matrix powder and the carbon nanoparticles form metallurgical bonding; and S4, the steps S2 and S3 are repeated till forming, and a workpiece is obtained through aftertreatment. The method has the advantages of high component control precision, high material utilization rate and capability of realizing a complex functional gradient structure.

Description

Technical Field

[0001] The present invention relates to the technical field of metal additive manufacturing, and in particular to an additive manufacturing process with controllable material composition based on laser powder bed melting. Background Art

[0002] Laser powder bed fusion (L-PBF) is an additive manufacturing (AM) technology widely used in the manufacture of metal parts. It is renowned for its design flexibility and efficient resource utilization. However, given the fundamental differences between the formation principles of L-PBF and traditional material removal techniques, in-depth evaluation and analysis of the material's microstructure and mechanical properties are essential. Due to the characteristics of the raw materials used in the L-PBF manufacturing process, various types of pores are easily formed within the material, which can lead to fatigue behavior during use. Since subsequent heat treatment processes are difficult to effectively improve defects within L-PBF-manufactured materials, the selection and optimization of processing conditions are crucial for improving material performance.

[0003] In the field of metal additive manufacturing, laser powder bed fusion technology occupies a prominent position and even has a dominant influence in some aspects. The main advantages of this technology include: the ability to produce multiple parts, including some large parts, at a high resolution; the process is relatively easy to understand and master, the forming process is stable, and the final manufacturing results are highly predictable. Although laser powder bed fusion technology has the above advantages, it also has several disadvantages and limitations. Traditional L-PBF technology faces the following challenges: First, the material composition is limited to premixed powder and cannot be dynamically adjusted during the printing process; second, if trace elements need to be added, alloying treatment must be carried out in advance, which not only increases the cost but also reduces the flexibility of the material; finally, in the multi-material printing process, due to the difference in melting points of different materials, defects are easily caused at the interface of the printed parts. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide an additive manufacturing process with controllable material composition based on laser powder bed melting in response to the above-mentioned deficiencies in the prior art, which has the advantages of high composition control accuracy, high material utilization rate, and the ability to realize complex functional gradient structures.

[0005] The above-mentioned object of the present invention is achieved through the following technical solutions: A material composition controllable additive manufacturing process based on laser powder bed fusion, comprising the following steps: S1 determines the composition gradient path of the printing material from the base area to the strengthening area of ​​the workpiece according to the preset three-dimensional model of the workpiece; S2 sprays a carbon nanoparticle solution in the strengthening area after laying the matrix powder layer by layer according to the composition gradient path of S1; S3 uses high scanning speed and low power parameters for L-PBF treatment in the matrix area, while low scanning speed and high power are used for L-PBF treatment in the strengthening area to form a metallurgical bond between the matrix powder and carbon nanoparticles; S4 repeats S2 and S3 until the workpiece is formed and then undergoes post-processing to obtain the workpiece.

[0006] Furthermore, in said S1, a stress analysis is first performed on a preset three-dimensional model of the workpiece, focusing on identifying the easily worn area of ​​the fillet subjected to periodic loads as the reinforcement area, and based on the mechanical performance requirements, determining the composition gradient path of the printing material from the workpiece substrate to the reinforcement area.

[0007] Furthermore, in S2, the matrix region and the strengthening region use H13 steel powder prepared by gas atomization as the matrix powder. The H13 steel powder prepared by gas atomization has high sphericity and good fluidity, which is conducive to uniform powder spreading in the L-PBF process.

[0008] Furthermore, in S2, the inkjet-printed carbon nanoparticle solution comprises the following raw materials in weight percentage: 1-3 wt% carbon powder, 80-90 wt% ethanol, 1-3 wt% dispersant, 0.5-1.0 wt% stabilizer, and 0.1-0.5 wt% viscosity modifier. The dispersant is BYK-190 from BYK, the stabilizer is polyvinylpyrrolidone (PVPK30) from BASF, and the viscosity modifier is hydroxyethyl cellulose (HEC) from Dow Chemical.

[0009] Furthermore, in S2, the particle size of the carbon nanoparticles in the carbon nanoparticle solution is 180-220 nm. The addition of a dispersant and a stabilizer ensures that the carbon nanoparticles are uniformly dispersed and do not settle.

[0010] Furthermore, in S3, the L-PBF laser power of the substrate region is controlled to be 220-250 W, the scanning speed is 1000-1200 mm / s, the layer thickness is 30-50 μm, the powder spreading speed is 50-70 mm / s, and the argon atmosphere is used for protection.

[0011] Furthermore, in the step S3, the laser power of the L-PBF in the strengthening zone is controlled to be 350-400 W, the scanning speed is controlled to be 600-800 mm / s, and the injection amount of the carbon nanoparticle solution is controlled to be 0.5-1.0 μL / mm 2 , layer thickness 30~50μm.

[0012] Furthermore, in S4, the formed workpiece is first subjected to a heating degreasing process in an argon protective atmosphere, followed by diffusion sintering at a temperature slightly below the melting point of the base material to form a strong bond between the carbon elements and the steel matrix. The heating degreasing process removes the ethanol solvent, dispersant, and stabilizer to prevent defects caused by sudden vaporization. By controlling the sintering temperature and holding time, excessive grain growth is prevented while ensuring interfacial bonding strength.

[0013] Furthermore, in the S4, the temperature of the degreasing is controlled to be first raised from room temperature to 300°C at 5°C / min, and then kept at this temperature for 1-2 hours under the protection of an argon atmosphere at a flow rate of 10-15 L / min.

[0014] Furthermore, in the above S4, the sintering temperature of the diffusion sintering is controlled to be 1250-1350° C., the heating rate is 10° C. / min, the holding time is 2-4 hours, and the cooling method is furnace cooling.

[0015] In summary, the beneficial technical effects of the present invention are as follows: the present invention integrates inkjet printing technology in the powder spreading process of laser powder bed fusion (L-PBF). After the L-PBF powder spreading, the composition ratio of each layer of powder is controlled in real time by precisely spraying a nanoparticle suspension of trace elements, thereby achieving local directional optimization of material properties such as hardness, strength, and toughness; through the coordinated control of the dynamic powder supply system and inkjet printing, the matching design of the composition gradient and the microstructure is ensured, solving the problem that traditional LPBF is difficult to flexibly adjust the material composition; the laser power and scanning speed are adjusted according to the composition to avoid thermal stress problems caused by differences in the melting points of elements, and has the advantages of high composition control precision, high material utilization, and the realization of complex functional gradient structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flowchart of the method provided in Example 1 of the present invention; Figure 2 This is a schematic diagram of the L-PBF device structure of the method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below with reference to the accompanying drawings and specific implementation methods.

[0018] Example 1: Reference Figure 1 and Figure 2 , which is a material composition controllable additive manufacturing process based on laser powder bed melting disclosed by the present invention, comprising the following steps: S1 determines the composition gradient path of the printing material from the base area to the strengthening area of ​​the workpiece according to the preset three-dimensional model of the workpiece; S2 sprays the carbon nanoparticle solution in the strengthening area after laying the matrix powder layer by layer according to the composition gradient path of S1; S3 uses high scanning speed and low power parameters for L-PBF treatment in the matrix area, while low scanning speed and high power are used for L-PBF treatment in the strengthening area to form a metallurgical bond between the matrix powder and carbon nanoparticles; S4 repeats S2 and S3 until the workpiece is formed and then undergoes post-processing to obtain the workpiece.

[0019] Example 2: This is a material composition controllable additive manufacturing process based on laser powder bed melting disclosed by the present invention. The difference from Example 1 is that it includes the following steps: S1 first performs stress analysis on the preset 3D model of the workpiece, focusing on identifying the wear-prone areas of the fillet that are subjected to periodic loads as the strengthening area. Based on the mechanical performance requirements, the composition gradient path of the printing material from the workpiece substrate to the strengthening area is determined; S2, after laying down the base powder layer by layer according to the composition gradient path of S1, sprays the carbon nanoparticle solution in the reinforcement area. The base powder in the base and reinforcement areas is H13 steel powder prepared by atomization. The inkjet-printed carbon nanoparticle solution is composed of the following raw materials in weight percentage: carbon powder 2wt%, ethanol 85wt%, dispersant 2wt%, stabilizer 0.8wt%, and viscosity modifier 0.3wt%. S3 uses high scanning speed and low power parameters for L-PBF treatment in the substrate area. The laser power of the L-PBF in the substrate area is controlled at 240W, scanning speed at 1200mm / s, layer thickness at 40μm, powder spreading speed at 60mm / s, and argon atmosphere protection. The strengthening area was treated with L-PBF at low scanning speed and high power. The laser power of L-PBF in the strengthening area was controlled to be 380W, the scanning speed was 600mm / s, and the injection volume of carbon nanoparticle solution was 1.0μL / mm 2 , layer thickness of 40 μm, so that the matrix powder and carbon nanoparticles form a metallurgical bond; After S4 forming, the workpiece is first heated and degreased in an argon protective atmosphere. The temperature of the heating and degreasing is controlled to be first heated from room temperature to 300℃ at 5℃ / min, and then kept warm for 1.5 hours under the protection of argon atmosphere at 15L / min; then diffusion sintering is carried out at a temperature slightly lower than the melting point of the matrix material, that is, the sintering temperature of the diffusion sintering is controlled to be 1350℃, the heating rate is 10℃ / min, the holding time is 3h, and the cooling method is furnace cooling, so that a strong bond is formed between the carbon element and the steel matrix.

[0020] Example 3: This is a material composition controllable additive manufacturing process based on laser powder bed melting disclosed by the present invention, which is different from Example 1 in that it includes the following steps: S1 first performs stress analysis on the preset 3D model of the workpiece, focusing on identifying the wear-prone areas of the fillet that are subjected to periodic loads as the strengthening area. Based on the mechanical performance requirements, the composition gradient path of the printing material from the workpiece substrate to the strengthening area is determined; S2, after laying down the base powder layer by layer according to the composition gradient path of S1, sprays the carbon nanoparticle solution in the reinforcement area. The base and reinforcement areas use H13 steel powder prepared by aerosolization as the base powder. The inkjet-printed carbon nanoparticle solution is composed of the following raw materials in weight percentage: carbon powder 1wt%, ethanol 80wt%, dispersant 1wt%, stabilizer 0.5wt%, and viscosity regulator 0.1wt%. S3 uses high scanning speed and low power parameters for L-PBF treatment in the substrate area. The laser power of the L-PBF in the substrate area is controlled at 220W, scanning speed at 1000mm / s, layer thickness at 30μm, powder spreading speed at 50mm / s, and argon atmosphere protection. The strengthening area was treated with L-PBF at low scanning speed and high power. The laser power of L-PBF in the strengthening area was controlled to be 350W, the scanning speed was 600mm / s, and the injection volume of carbon nanoparticle solution was 0.5μL / mm 2 , layer thickness of 30 μm, so that the matrix powder and carbon nanoparticles form a metallurgical bond; After S4 forming, the workpiece is first heated and degreased in an argon protective atmosphere. The temperature of the heating and degreasing is controlled to be first heated from room temperature to 300℃ at 5℃ / min, and then kept warm for 1h under the protection of argon atmosphere at 10L / min; then diffusion sintering is carried out at a temperature slightly lower than the melting point of the matrix material, that is, the sintering temperature of the diffusion sintering is controlled to be 1250℃, the heating rate is 10℃ / min, the holding time is 2h, and the cooling method is furnace cooling, so that a strong bond is formed between the carbon element and the steel matrix.

[0021] Example 4: This is a material composition controllable additive manufacturing process based on laser powder bed melting disclosed by the present invention, which is different from Example 1 in that it includes the following steps: S1 first performs stress analysis on the preset 3D model of the workpiece, focusing on identifying the wear-prone areas of the fillet that are subjected to periodic loads as the strengthening area. Based on the mechanical performance requirements, the composition gradient path of the printing material from the workpiece substrate to the strengthening area is determined; S2, after laying down the base powder layer by layer according to the composition gradient path of S1, sprays a carbon nanoparticle solution in the reinforcement area. The base and reinforcement areas use H13 steel powder prepared by aerosolization as the base powder. The inkjet-printed carbon nanoparticle solution consists of the following raw materials in weight percentage: carbon powder 2wt%, ethanol 88wt%, dispersant 2wt%, stabilizer 0.7wt%, and viscosity modifier 0.2wt%. S3 uses high scanning speed and low power parameters for L-PBF treatment in the substrate area. The laser power of the L-PBF in the substrate area is controlled at 230W, scanning speed at 1100mm / s, layer thickness at 45μm, powder spreading speed at 55mm / s, and argon atmosphere protection. The strengthening area was treated with L-PBF at low scanning speed and high power. The laser power of L-PBF in the strengthening area was controlled to be 370W, the scanning speed was 700mm / s, and the injection volume of carbon nanoparticle solution was 0.8μL / mm 2 , layer thickness of 45 μm, so that the matrix powder and carbon nanoparticles form a metallurgical bond; After S4 forming, the workpiece is first heated and degreased in an argon protective atmosphere. The temperature of the heating and degreasing is controlled to be first heated from room temperature to 300℃ at 5℃ / min, and then kept warm for 1.5 hours under the protection of argon atmosphere at 12L / min; then diffusion sintering is carried out at a temperature slightly lower than the melting point of the matrix material, that is, the sintering temperature of the diffusion sintering is controlled to be 1300℃, the heating rate is 10℃ / min, the holding time is 3h, and the cooling method is furnace cooling, so that a strong bond is formed between the carbon element and the steel matrix.

[0022] Example 5: This is a material composition controllable additive manufacturing process based on laser powder bed melting disclosed by the present invention, which is different from Example 1 in that it includes the following steps: S1 first performs stress analysis on the preset 3D model of the workpiece, focusing on identifying the wear-prone areas of the fillet that are subjected to periodic loads as the strengthening area. Based on the mechanical performance requirements, the composition gradient path of the printing material from the workpiece substrate to the strengthening area is determined; S2, after laying down the base powder layer by layer according to the composition gradient path of S1, sprays the carbon nanoparticle solution in the reinforcement area. The base powder in the base and reinforcement areas is H13 steel powder prepared by aerosolization. The inkjet-printed carbon nanoparticle solution is composed of the following raw materials in weight percentage: carbon powder 3wt%, ethanol 90wt%, dispersant 3wt%, stabilizer 1.0wt%, and viscosity modifier 0.5wt%. S3 uses high scanning speed and low power parameters for L-PBF treatment in the substrate area. The laser power of the L-PBF in the substrate area is controlled at 250W, scanning speed at 1200mm / s, layer thickness at 50μm, powder spreading speed at 70mm / s, and argon atmosphere protection. The strengthening area was treated with L-PBF at low scanning speed and high power. The laser power of L-PBF in the strengthening area was controlled to be 400W, the scanning speed was 800mm / s, and the injection volume of carbon nanoparticle solution was 1.0μL / mm 2 , layer thickness of 50 μm, so that the matrix powder and carbon nanoparticles form a metallurgical bond; After S4 forming, the workpiece is first heated and degreased in an argon protective atmosphere. The temperature of the heating and degreasing is controlled to be first heated from room temperature to 300℃ at 5℃ / min, and then kept warm for 2h under the protection of argon atmosphere at 15L / min; then diffusion sintering is carried out at a temperature slightly lower than the melting point of the matrix material, that is, the sintering temperature of the diffusion sintering is controlled to be 1350℃, the heating rate is 10℃ / min, the holding time is 4h, and the cooling method is furnace cooling, so that a strong bond is formed between the carbon element and the steel matrix.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A compositionally controllable additive manufacturing process based on laser powder bed fusion, characterized by: The following steps are included: S1 determines the composition gradient path of the printing material from the base area to the strengthening area of ​​the workpiece according to the preset three-dimensional model of the workpiece; S2 sprays a carbon nanoparticle solution in the strengthening area after laying the matrix powder layer by layer according to the composition gradient path of S1; S3 uses high scanning speed and low power parameters for L-PBF treatment in the matrix area, while low scanning speed and high power are used for L-PBF treatment in the strengthening area to form a metallurgical bond between the matrix powder and carbon nanoparticles; S4 repeats S2 and S3 until the workpiece is formed and then undergoes post-processing to obtain the workpiece.

2. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In S1, a stress analysis is first performed on a preset three-dimensional model of the workpiece, focusing on identifying the easily worn area of ​​the fillet that is subjected to periodic loads as the reinforcement area, and based on the mechanical performance requirements, determining the composition gradient path of the printing material from the workpiece substrate to the reinforcement area.

3. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In the step S2, the matrix region and the strengthening region use H13 steel powder prepared by gas atomization as the matrix powder.

4. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In S2, the carbon nanoparticle solution for inkjet printing is composed of the following raw materials in weight percentage: 1-3 wt% of carbon powder, 80-90 wt% of ethanol, 1-3 wt% of dispersant, 0.5-1.0 wt% of stabilizer, and 0.1-0.5 wt% of viscosity regulator.

5. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In the step S2, the particle size of the carbon nanoparticles in the carbon nanoparticle solution is 180-220 nm.

6. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In S3 , the L-PBF laser power of the substrate region is controlled to be 220-250 W, the scanning speed to be 1000-1200 mm / s, the layer thickness to be 30-50 μm, the powder spreading speed to be 50-70 mm / s, and the argon atmosphere to be protected.

7. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In the above step S3, the laser power of the L-PBF in the strengthening area is controlled to be 350-400 W, the scanning speed is controlled to be 600-800 mm / s, and the injection amount of the carbon nanoparticle solution is controlled to be 0.5-1.0 μL / mm. 2 , layer thickness 30~50μm.

8. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In the above-mentioned S4, the formed workpiece is first heated and degreased in an argon protective atmosphere, and then diffusion sintered at a temperature slightly lower than the melting point of the matrix material to form a strong bond between the carbon element and the steel matrix.

9. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In the above S4, the temperature of the degreasing process is controlled to be raised from room temperature to 300°C at a rate of 5°C / min, and then kept at this temperature for 1-2 hours under the protection of an argon atmosphere at a rate of 10-15 L / min.

10. The additive manufacturing process with controllable material composition based on laser powder bed fusion according to claim 1, characterized in that: In the above S4, the sintering temperature of the diffusion sintering is controlled to be 1250-1350° C., the heating rate is 10° C. / min, the holding time is 2-4 hours, and the cooling method is furnace cooling.

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