High-performance alloy component with low carbon content and high density and 3d printing method thereof

Abstract

The application relates to the field of additive manufacturing, in particular to a high-performance alloy component with low carbon content and high density and a 3D printing method thereof. The method comprises the following steps: drying high-carbon-sensitive alloy powder, designing a core-shell structure model, 3D printing, heat curing, sintering, and obtaining the high-performance alloy component with low carbon content and high density. The core-shell structure model comprises a shell region and a core region, and the binder saturation degree of the shell region is controlled to be 30-100% and the binder saturation degree of the core region is controlled to be 0% during the 3D printing process. The method combines the selection of low residual carbon binder, the design of the core-shell structure and the differential injection of the binder, so that the 3D printed alloy component forms a gas resolution channel in the sintering process, reduces the gas escape distance, reduces the local residual carbon accumulation caused by the carbon retention in the core, and solves the problems of organization segregation or brittle phase generation. Moreover, the prepared alloy component has high density, low porosity and good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, specifically to a high-performance alloy component with low carbon content and high density, and its 3D printing method. Background Technology

[0002] With the widespread application of additive manufacturing technology in aerospace, energy equipment, and biomedicine, binder jetting 3D printing has become an important development direction in the fabrication of powder-based metal components due to its advantages such as high forming efficiency, lack of support structure limitations, and suitability for mass production of complex structures. However, for certain alloy materials with high carbon sensitivity (such as some high-strength steels, titanium alloys, or nickel-based superalloys), traditional binder jetting 3D printing methods face the following challenges in the forming and sintering processes:

[0003] (1) Carbon source enrichment occurs during the pyrolysis process of the binder. Conventional organic or high-residue binders are not easily decomposed during heat treatment. Especially in the core area of ​​the printed part, carbon is difficult to escape, which can easily cause local carbon accumulation, resulting in microsegregation or brittle phase formation.

[0004] (2) Difficulty in controlling structural compactness: High-carbon sensitive alloys are extremely sensitive to residual carbon. Excessive use of binder or uneven forming density will affect subsequent compaction, resulting in high porosity and decreased mechanical properties of components.

[0005] (3) Stress concentration and carbon residue are difficult to coordinate and control during heat treatment: Traditional uniform structure design cannot take into account the release path of pyrolysis products in complex geometry, especially in thick-walled areas or inside closed structures, which can easily lead to carbon residue accumulation and sintering defects.

[0006] Therefore, there is an urgent need for a 3D printing method suitable for high carbon-sensitive alloys to solve the above problems. Summary of the Invention

[0007] To address the technical problems existing in the prior art, the present invention aims to provide a high-performance alloy component with low carbon content and high density, and a 3D printing method thereof. This method is applicable to the printing of high-carbon-sensitive alloys.

[0008] This invention aims to solve the technical problems of residual carbon, poor sintering density, and degradation of mechanical properties in the binder jet 3D printing process of high carbon sensitive alloys in the prior art. It proposes a 3D printing method that combines powder pretreatment, core-shell structure modeling and zoned differentiated jetting control to reduce carbon residue from the source and improve forming stability and material properties.

[0009] According to a first aspect of the present invention, the present invention provides a 3D printing method for high-performance alloy components with low carbon content and high density; the method includes the following steps:

[0010] (1) The high carbon sensitive alloy powder is dried to obtain the dried high carbon sensitive alloy powder.

[0011] (2) Design a core-shell structure model according to the required component structure, load the dried high carbon sensitive alloy powder described in step (1) into the powder hopper of 3D printing, and perform 3D printing;

[0012] (3) The printed components described in step (2) are subjected to thermosetting and sintering treatment to obtain high-performance alloy components with low carbon content and high density.

[0013] In step (2), the core-shell structure model includes a shell region and a core region. During the 3D printing process, the saturation of the binder in the shell region is controlled at 30-100%, and the saturation of the binder in the core region is controlled at 0%. Differentiated adhesive spraying is applied to the core region and the shell region.

[0014] In some implementations, during the 3D printing process, the binder saturation in the shell region is controlled at 80-100%, and the binder saturation in the core region is controlled at 0%.

[0015] In some embodiments, the core-shell structure model includes a shell region and a core region, which are bonded together. The core-shell structure model is constructed by adaptively designing the shell thickness based on the structural complexity of the printed component, variations in wall thickness, and the thermal decomposition characteristics of the selected binder. This invention achieves spatially differentiated control by adjusting the binder spray saturation, guiding the outward diffusion of pyrolysis products.

[0016] In some embodiments, the shell region can be divided into a distal core region (i.e., the area of ​​the shell region far from the core region) and a proximal core region (i.e., the area of ​​the shell region close to the core region). The distal core region is connected to the proximal core region, and the proximal core region is connected to the core region. The thickness of the proximal core region is 1–4 mm. The binder saturation in the proximal core region is controlled at 60–80%, while the binder saturation in the distal core region is controlled at 90–100%. However, overall, the binder saturation of the shell region (including the proximal and distal core regions) is controlled at 80–100%. This invention, by controlling the binder saturation in each region, allows for a larger amount of binder sprayed in the shell region, forming a highly dense barrier structure (increasing shell density), facilitating gas extraction (promoting gas escape through differences in binder saturation), and maintaining a high strength level of the green body after thermosetting.

[0017] In some embodiments, the high carbon sensitive alloy powder in step (1) is at least one of the following: high entropy alloy, titanium, titanium alloy, copper, copper alloy, aluminum alloy, and nickel alloy. High carbon sensitive alloy powder refers to a type of metal powder material that reacts significantly to changes in carbon content. The properties of alloy components prepared from it (such as mechanical strength and elongation) will change drastically with small fluctuations in carbon content.

[0018] In some embodiments, the high-carbon sensitive alloy powder described in step (1) is graded and sieved before use to control the particle size of the high-carbon sensitive alloy powder to below 50 μm. Grading and sieving can remove agglomerates.

[0019] In some embodiments, the drying temperature in step (1) is no higher than 200°C, and the drying time is 1 to 3 hours; the drying is carried out under a vacuum of less than 30 Pa. The drying temperature being no higher than 200°C maximizes the preservation of powder surface activity while avoiding the risks of heat-induced surface oxidation, binder pre-reaction, and carbon source enrichment.

[0020] In some embodiments, the drying process in step (1) is carried out at a temperature of 100-170°C.

[0021] In some implementations, the shell thickness in the core-shell structure model described in step (2) is 2-10 mm. There are no requirements regarding the core thickness. The shell thickness is automatically adjusted during construction based on the minimum wall thickness of the components, the distribution of heat flow channels, and volumetric dimensions to prevent problems with the efficient emission of residual carbon from the core due to improper shell thickness design.

[0022] In some implementations, the shell thickness in the core-shell structure model described in step (2) is 3-6 mm;

[0023] In some embodiments, both the core and shell regions are solid structures. While both are high-density solid structures, the method of this invention employs a differentiated control strategy for the saturation of the sprayed binder to guide the outward escape of thermal decomposition products from the core region, thereby improving gas permeability and carbon release efficiency.

[0024] In some embodiments, the density of the core region and the shell region are both 40-70% in the 3D printing. The forming densities of the core and shell regions are kept consistent during the 3D printing process.

[0025] In some implementations, in the core-shell structure model described in step (2), the thickness of the shell region is 3-6 mm; during the 3D printing process, the forming density of the core region and the shell region remains consistent.

[0026] In some embodiments, the 3D printing method in step (2) is binder jet 3D printing; the 3D printing is performed layer by layer using the following parameters: powder bed temperature is 30-70℃, single layer drying time is 3-15s, powder spreading roller rotation speed is 200-380rpm, single layer powder thickness is 50-150μm, and powder spreading speed is 1-15mm / s.

[0027] In some embodiments, the adhesive used in the 3D printing of step (2) is an oil-based adhesive or a water-based adhesive;

[0028] In some embodiments, the oil-based adhesive is a phenolic resin adhesive; the phenolic resin adhesive is manufactured by Wuhan Yizhi Technology Co., Ltd.

[0029] In some embodiments, the water-based adhesive is at least one of ExOne BA005 and ExOne BS004. ExOne BA005 and ExOne BS004 are manufactured by ExOne Corporation, USA.

[0030] The binders selected in this invention are all low-carbon volatile binders with a pyrolysis temperature of less than 300°C.

[0031] In some embodiments, the thermosetting process in step (3) includes: heating the 3D-printed integral powder hopper to 120–350°C and holding it at that temperature for 1–6 hours to obtain a green body that has undergone thermosetting. The thermosetting process stabilizes the green body structure.

[0032] In some embodiments, the thermosetting process in step (3) includes: heating the 3D-printed powder hopper to 120-200°C and holding it at that temperature for 1-3 hours to obtain a green blank that has undergone thermosetting.

[0033] In some implementations, the sintering process is segmented sintering;

[0034] In some embodiments, the sintering process is carried out at a vacuum level below 10. -2 The sintering process is carried out in the Pa sintering furnace;

[0035] In some embodiments, the sintering process includes the following steps: first, holding at 400–900°C for 0.5–4 hours, then holding at 900–1000°C for 0.5–3 hours, and finally holding at 1000–1500°C for 1–4 hours. The sintering process promotes complete pyrolysis and removal of the binder (complete escape of the carbon source), resulting in improved density and reduced carbon content in the high-carbon sensitive alloy components.

[0036] This invention provides a 3D printing method for high-performance alloy components with low carbon content and high density, applicable to the printing of high-carbon-sensitive alloys. Furthermore, this method is suitable not only for printing components with simple structures but also for printing components with complex morphologies, porous walls with interlaced structures, or high structural integrity requirements with gradient strength. Components printed using this method have a residual carbon content of less than 0.01 wt%, and the overall mechanical properties of the resulting alloy components are superior to those obtained using traditional binder jet 3D printing methods.

[0037] According to a second aspect of the present invention, the present invention provides a high-performance alloy component with low carbon content and high density prepared by the above-described 3D printing method, wherein the residual carbon content is less than 0.01 wt% and the density is ≥98%.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) The carbon residue of the alloy components prepared by the method provided by the present invention is significantly reduced. The method combines the selection of low carbon residue binder, the design of core-shell structure, and the differential spraying of binder to enable the 3D printed alloy components to form degassing channels during sintering, reduce the distance of decomposition gas escape, reduce the local carbon residue accumulation formed by carbon retention in the core, and solve the problem of microstructure segregation or brittle phase formation.

[0040] (2) The method provided by the present invention can improve the density of alloy components. The method provided by the present invention optimizes the pyrolysis path and sintering shrinkage path by differentiating the spraying strategy. On the one hand, it reduces the use of binder from the source. On the other hand, it takes into account the release path of pyrolysis products of the shaped body and the sintering shrinkage path, reduces the accumulation of residual carbon, increases the density of the shaped body, and avoids defects caused by carbon residue accumulation.

[0041] (3) The method provided by the present invention can be applied to the printing of complex structures and is suitable for the manufacturing of high-performance parts with complex geometry, thin-walled-thick-walled transition and gradient functional structure;

[0042] (4) The method and process provided by the present invention have strong adaptability and are applicable to a variety of high carbon sensitive alloy powders, and have the potential for industrial promotion.

[0043] (5) The alloy components prepared by the method provided by the present invention have high density, low porosity and good mechanical properties, which are superior to alloy components prepared by existing processes. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 The schematic diagram and cross-sectional view of the core-shell structure model provided in the embodiments of the present invention;

[0046] Where 1 represents the shell region and 2 represents the core region;

[0047] Figure 2Metallographic image of the low-carbon, high-density high-performance alloy component prepared in Example 1 at the core-shell structure interface;

[0048] Figure 3 Metallographic image of the core region of the high-performance alloy component with low carbon content and high density prepared in Example 1;

[0049] Figure 4 SEM image of the high-performance alloy component with low carbon content and high density prepared in Example 1;

[0050] Figure 5 Metallographic image of the alloy component prepared in Comparative Example 1;

[0051] Figure 6 Stress-strain diagrams of alloy components prepared by the 3D printing method (core-shell printing method) of Example 1 and the conventional printing method of Comparative Example 1 are shown.

[0052] Figure 7 SEM image of the alloy component prepared in Comparative Example 1;

[0053] Figure 8 Metallographic image of the low-carbon, high-density high-performance alloy component prepared in Example 2 at the core-shell structure interface;

[0054] Figure 9 SEM images of alloy components prepared under experimental conditions 2 in Table 2 of Comparative Example 2;

[0055] Figure 10 SEM image of the alloy component prepared under experimental conditions number 4 in Table 2 of Comparative Example 2;

[0056] Figure 11 SEM image of the alloy component prepared under the experimental conditions of No. 6 in Table 2 of Comparative Example 2. Detailed Implementation

[0057] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0058] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0059] The 3D printing equipment used in the following examples and comparative examples was provided by ExOne Inc., USA, and the model is Innovent+.

[0060] The mechanical property tests in the following examples and comparative examples were performed in accordance with the methods described in the literature (Enhancing mechanical properties and electrochemical behavior of equiatomic FeNiCoCr high-entropy alloy through sintering and hot isostatic pressing for binder jet 3D printing).

[0061] The residual carbon content of the alloy components in the following examples and comparative examples was detected by a carbon-sulfur analyzer; the manufacturer of the carbon-sulfur analyzer was LECO (Laboratory Equipment Corporation), model CS6.

[0062] The NiCoCr-based high-entropy alloy powder used in the following examples and comparative examples is Ni 34 Co 28 Cr 28 Al 10 Its composition can be found in the reference (Study on densification behavior and microstructure properties of NiCoCr-based high-entropy alloys printed by binder jetting 3D printing).

[0063] The titanium alloy powder used in the following examples is manufactured by AVIC MAT Powder Metallurgy Technology (Beijing) Co., Ltd., and the model is TC4 alloy powder.

[0064] The nickel-based superalloy powder used in the following examples is manufactured by Xi'an Ouzhong Materials Technology Co., Ltd., and its model is GH3044 alloy powder.

[0065] Example 1

[0066] This embodiment provides a 3D printing method for high-performance alloy components with low carbon content and high density. This method is used for binder jet 3D printing of NiCoCr-based high-entropy alloys. The method includes the following steps:

[0067] (1) Pretreatment of powder: NiCoCr high-entropy alloy powder is graded and sieved to remove agglomerates and control the particle size to below 50μm; then the sieved powder is subjected to low-temperature drying treatment under vacuum of less than 30Pa and 160℃ for 2h to obtain pretreated alloy powder.

[0068] (2) Construction of the core-shell structure model: As an example, a core-shell structure STL format model with an external shape of 60×40×20mm is constructed (e.g., Figure 1 As shown, Figure 1The diagram and cross-sectional view of the core-shell structure model provided in the embodiment of the present invention are shown. The core-shell structure model includes a shell region 1 and a core region 2, wherein the shell region 1 encloses the core region 2. Both the core region and the shell region are solid structures and are connected to each other. The shell region and the core region are attached together, and the thickness of the shell region is 3mm.

[0069] (3) The pretreated alloy powder was loaded into the powder hopper of the 3D printer. The 3D printing method was binder jet 3D printing. The 3D printing parameters were set as follows: powder bed temperature 50℃, single layer drying time 10s, powder spreading roller rotation speed 230rpm, single layer powder thickness 50μm, powder spreading speed 1mm / s, and ultrasonic strength 70%. During the 3D printing process, the binder saturation in the shell area was controlled at 80%, and the binder saturation in the core area was controlled at 0%. The forming density of the core area and the shell area was kept consistent during the 3D printing. The binder used was ExOne BA005 produced by ExOne Corporation of the United States.

[0070] (4) Thermosetting and Vacuum Sintering: After 3D printing, the entire chamber is thermoset to enhance structural stability (thermosetting temperature is 180℃, time is 4h), and then the printed green body is sintered under a vacuum of less than 10℃. -2 In the Pa sintering furnace, the temperature is raised to 1270℃ and sintered in stages for 4 hours. During the 4-hour sintering process, the temperature is first held at 600℃ for 4 hours, then held at 900℃ for 1 hour, and finally held at 1270℃ for 4 hours to obtain high-performance alloy components with low carbon content and high density.

[0071] The mechanical properties of the alloy component (i.e., a low-carbon, high-density high-performance alloy component) formed by the binder jet 3D printing method provided in this embodiment are as follows: yield strength 617 MPa, tensile strength 870 MPa, and elongation 18.1%. The density of this low-carbon, high-density high-performance alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was 99.16%. Furthermore, the residual carbon content of this low-carbon, high-density high-performance alloy component is 0.004 wt%, which is less than 0.01 wt%.

[0072] Figure 2 This is a metallographic image of the low-carbon, high-density, high-performance alloy component prepared in Example 1 at the core-shell structure interface. Figure 3 This is a metallographic image of the core region of the low-carbon, high-density, high-performance alloy component prepared in Example 1. (From...) Figure 2 and Figure 3It is known that the core region without binder spray has fewer pores (gas holes) after sintering due to the absence of gases generated by binder pyrolysis, thus avoiding the influence of porosity on mechanical properties. The resulting alloy component can maintain good mechanical properties. On the other hand, the shell region has certain pores after sintering due to the presence of gases generated during the binder pyrolysis process. These pores are degassing channels, which can reduce the local residual carbon accumulation caused by carbon retention in the core, solve the problem of microstructure segregation or brittle phase formation, and thus avoid the influence of local residual carbon accumulation on the mechanical properties of the alloy component. Figure 4 SEM image of the low-carbon, high-density, high-performance alloy component prepared in Example 1; by Figure 4 It can be seen that the high-performance alloy component with low carbon content and high density prepared in Example 1 has no obvious second phase, that is, there is no local residual carbon accumulation.

[0073] Comparative Example 1

[0074] Comparative Example 1 provides a conventional binder jet 3D printing method for NiCoCr-based high-entropy alloys; the method includes the following steps:

[0075] (1) Pretreatment of powder: NiCoCr high-entropy alloy powder is graded and sieved to remove agglomerates, so that the particle size of the alloy powder is controlled below 50μm; then the sieved alloy powder is subjected to low-temperature drying treatment under vacuum of less than 30Pa and 160℃ for 2h to obtain pretreated alloy powder.

[0076] (2) Construction of the basic model: Construct a solid model in STL format with a size of 60×40×20mm (the difference from the model in Example 1 is that the model in Comparative Example 1 does not have a shell region and a core region);

[0077] (3) The pretreated alloy powder is loaded into the powder hopper of the 3D printer. The 3D printing method is binder jet 3D printing. The 3D printing parameters are set as follows: powder bed temperature 50℃, drying time 10s, powder spreading roller rotation 230rpm, powder layer thickness 50μm, ultrasonic strength 70%, binder saturation 80%.

[0078] (4) Thermosetting and Vacuum Sintering: After printing, the entire chamber is thermoset to enhance structural stability (thermosetting temperature is 180℃, time is 4h), and then the printed green compact is sintered under a vacuum of less than 10℃. -2 In the Pa sintering furnace, the temperature is raised to 1270℃ and sintered in stages for 4 hours. During the 4-hour sintering process, the temperature is first held at 600℃ for 4 hours, then held at 900℃ for 1 hour, and finally held at 1270℃ for 4 hours to obtain the alloy component.

[0079] The mechanical properties of the alloy component formed by the conventional binder jet 3D printing method in Comparative Example 1 were tested and found to be: yield strength 588 MPa, tensile strength 639 MPa, and elongation 2.3%. The density of the alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was 97.77%. The residual carbon content of the alloy component was 0.121 wt%.

[0080] Figure 3 Metallographic image of the high-performance alloy component with low carbon content and high density prepared in Example 1; Figure 5 Metallographic image of the alloy component prepared in Comparative Example 1; Figure 3 and Figure 5 The black area at the top represents pores. Figure 3 and Figure 5 As can be seen above, the alloy component obtained by the 3D printing method (existing conventional method) provided in Comparative Example 1 has a significantly higher number of pores than the alloy component prepared in Example 1. More pores lead to a deterioration in the mechanical properties of the part. The 3D printing method provided in Example 1 significantly reduces the number of pores in the alloy component, and compared to Comparative Example 1, the pores in the alloy component of Example 1 are closed, reducing the impact of pores appearing after sintering on the mechanical properties of the alloy component.

[0081] Figure 6 Stress-strain diagrams of alloy components prepared by the 3D printing method of Example 1 (core-shell printing) and the 3D printing method of Comparative Example 1 (existing conventional method) are shown. Figure 6 According to the mechanical property data of the alloy component in Example 1 and the mechanical properties of the alloy component in Comparative Example 1, compared with the method in Comparative Example 1, the 3D printing method provided by Example 1 of the present invention significantly improves the plasticity, ductility and fracture toughness of the alloy component without sacrificing the strength index. The method of Example 1 has the ability to simultaneously optimize the strength and plasticity of the alloy component.

[0082] Figure 7 SEM images of the alloy components prepared in Comparative Example 1; from Figure 7 and Figure 4 In comparison, the alloy component prepared in Example 1 does not have a second phase and does not have local residual carbon accumulation, while the alloy component prepared in Comparative Example 1 has local residual carbon accumulation.

[0083] Example 2

[0084] Example 2 is basically the same as Example 1, except that: during the 3D printing process, the saturation of the binder in the shell region is controlled at 90%, and the saturation of the binder in the core region is controlled at 0%.

[0085] The mechanical properties of the alloy component prepared by the method in Example 2 were tested and found to be: yield strength 698 MPa, tensile strength 941 MPa, and elongation 25.3%. The density of the low-carbon, high-density high-performance alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was 98.13%. Furthermore, the residual carbon content of this low-carbon, high-density high-performance alloy component was 0.009 wt%, less than 0.01 wt%.

[0086] Figure 8 Metallographic image of the low-carbon, high-density, high-performance alloy component prepared in Example 2 at the core-shell interface. Figure 8 It is known that the core region without binder spray has fewer pores (gas holes) and closed pores due to the absence of gas generated by binder pyrolysis, thus avoiding the influence of pores on mechanical properties. The resulting alloy component can maintain good mechanical properties. On the other hand, the shell region has certain pores after sintering due to the presence of gas generated during the binder pyrolysis process. These pores are degassing channels, which can reduce the local residual carbon accumulation formed by carbon retention in the core, solve the problem of microstructure segregation or brittle phase formation, and thus avoid the influence of local residual carbon accumulation on the mechanical properties of the alloy component.

[0087] Example 3

[0088] Example 3 is basically the same as Example 1, except that: during the 3D printing process, the saturation of the binder in the shell region is controlled at 100%, and the saturation of the binder in the core region is controlled at 0%.

[0089] The mechanical properties of the low-carbon, high-density high-performance alloy component prepared by the method in Example 3 were tested and found to be: yield strength of 713 MPa, tensile strength of 817 MPa, and elongation of 11.7%. The density of this low-carbon, high-density high-performance alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was found to be 98.21%. Furthermore, the residual carbon content of this low-carbon, high-density high-performance alloy component was 0.007%, less than 0.01 wt%.

[0090] Example 4

[0091] Example 4 is basically the same as Example 1, except that: the core-shell structure model includes a core region and a shell region; the shell region is divided into a far-core region (i.e., the area of ​​the shell region far from the core region) and a near-core region (i.e., the area of ​​the shell region close to the core region), wherein the far-core region is connected to the near-core region, and the near-core region is connected to the core region, and the thickness of the near-core region is 1 mm; the binder saturation of the near-core region is controlled at 80%, while the binder saturation of the far-core region is controlled at 100%.

[0092] The mechanical properties of the alloy component prepared by the method in Example 4 were tested and found to be: yield strength 740 MPa, tensile strength 833 MPa, and elongation 12.3%. The density of the low-carbon, high-density high-performance alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was 98.68%. Furthermore, the residual carbon content of this low-carbon, high-density high-performance alloy component was 0.008 wt%, less than 0.01 wt%.

[0093] Example 5

[0094] Example 5: To investigate the effect of binder selection on alloy components, a series of experiments were conducted. The experimental conditions and the mechanical properties and density parameters of the prepared alloy components are shown in Table 1 below. All other conditions were the same as in Example 1. The oil-based binder (phenolic-based) was a phenolic resin adhesive, manufactured by Wuhan Yizhi Technology Co., Ltd. The water-based binder was ExOne BA005 or ExOne BS004, manufactured by ExOne Corporation, USA.

[0095] Table 1

[0096]

[0097]

[0098] As shown in Table 1, alloy components prepared by 3D printing using water-based binders exhibit better mechanical properties.

[0099] Comparative Example 2

[0100] Comparative Example 2: To investigate the effect of differentiated binder spraying in the shell and core regions on alloy components, a series of experiments were conducted. The experimental conditions and the mechanical properties and density parameters of the alloy components obtained are shown in Table 2 below. All other conditions were the same as in Example 1.

[0101] Table 2

[0102]

[0103] In the experiments corresponding to serial numbers 8 and 9 in Table 2, due to the low saturation of the binder in the shell region, a formed green blank could not be obtained during the 3D printing process in step (3), so there is no relevant result data.

[0104] As shown in Table 2, the lower the binder saturation in the core region, the better the mechanical properties of the alloy component, especially the elongation. This is because the lower the binder saturation in the core region, the lower the porosity in the alloy component, and the less the second phase caused by residual carbon (i.e., local residual carbon accumulation).

[0105] The alloy components prepared in experiments 2, 4 and 6 in Table 2 were selected for SEM observation. Figure 9 SEM images of alloy components prepared under experimental conditions 2 in Table 2 of Comparative Example 2;

[0106] Figure 10 SEM image of the alloy component prepared under experimental conditions number 4 in Table 2 of Comparative Example 2; Figure 11 SEM images of the alloy components prepared under the experimental conditions of item 6 in Table 2 of Comparative Example 2. From... Figures 9-11 It can be seen that when the core region binder saturation is 20-80%, there is local carbon accumulation on these alloy components, and their mechanical properties are worse than those of alloy components prepared under the condition of 0% core region binder saturation (i.e., Example 1).

[0107] Example 6

[0108] This embodiment provides a 3D printing method for high-performance alloy components with low carbon content and high density; the method includes the following steps:

[0109] (1) Pretreatment of powder: The high carbon sensitive alloy powder (titanium alloy powder is selected here) is graded and sieved to remove agglomerates and control the particle size to below 50μm; then the sieved powder is subjected to low-temperature drying treatment under vacuum of less than 30Pa and temperature of 195℃ for 3h to obtain pretreated alloy powder.

[0110] (2) Construction of the core-shell structure model: Construct a hollow core-shell structure model in STL format with an outer shape of 60×40×20mm and a shell thickness of 3mm (refer to...). Figure 1 As shown in the figure, the core-shell structure model includes a shell region and a core region, wherein the shell region encloses the core region and the shell region has a thickness of 10 mm.

[0111] (3) The pretreated alloy powder was loaded into the powder hopper of the 3D printer. The 3D printing method was binder jet 3D printing. The 3D printing parameters were set as follows: powder bed temperature 70℃, single layer drying time 150s, powder spreading roller rotation speed 380rpm, single layer powder thickness 150μm, powder spreading speed 15mm / s, and ultrasonic strength 100%. During the 3D printing process, the binder saturation in the shell area was controlled at 100%, and the binder saturation in the core area was controlled at 0%. The forming density of the core area and the shell area was kept consistent during the 3D printing. The binder used was BA005 produced by ExOne, USA.

[0112] (4) Thermosetting and Vacuum Sintering: After 3D printing, the entire chamber is thermoset to enhance structural stability (thermosetting temperature is 350℃, time is 1h), and then the printed green body is sintered under a vacuum of less than 10℃. -2Segmented heating sintering is carried out in Pa's sintering furnace. During the sintering process, the temperature is first held at 900℃ for 0.5h, then held at 1000℃ for 0.5h, and finally held at 1500℃ for 1h to obtain high-performance alloy components with low carbon content and high density.

[0113] Tests showed that the mechanical properties of the alloy (i.e., a low-carbon, high-density high-performance alloy component) formed by binder jet 3D printing using this method are as follows: yield strength 775 MPa, tensile strength 863 MPa, and elongation 13.2%. The density of the low-carbon, high-density high-performance alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was 98.95%. Furthermore, the residual carbon content of this low-carbon, high-density high-performance alloy component is 0.007%, less than 0.01 wt%.

[0114] Example 7

[0115] This embodiment provides a 3D printing method for high-performance alloy components with low carbon content and high density; the method includes the following steps:

[0116] (1) Pretreatment of powder: The high carbon sensitive alloy powder (nickel-based high temperature alloy powder is selected here) is graded and sieved to remove agglomerates and control the particle size to below 50 μm; then the sieved powder is subjected to low-temperature drying treatment under vacuum of less than 30 Pa and temperature of 100 °C for 1 h to obtain the pretreated alloy powder.

[0117] (2) Construction of the core-shell structure model: Construct a core-shell structure STL format model with an external diameter of 60×40×20mm (refer to...). Figure 1 As shown, the core-shell structure model includes a shell region and a core region, where the shell region encloses the core region, and the shell region has a thickness of 2 mm.

[0118] (3) The pretreated alloy powder was loaded into the powder hopper of the 3D printer. The 3D printing method was binder jet 3D printing. The 3D printing parameters were set as follows: powder bed temperature 30℃, single layer drying time 3s, powder spreading roller rotation speed 200rpm, single layer powder thickness 50μm, powder spreading speed 1mm / s, and ultrasonic strength 20%. During the 3D printing process, the binder saturation in the shell area was controlled at 80%, and the binder saturation in the core area was controlled at 0%. The forming density of the core area and the shell area was kept consistent during the 3D printing. The binder used was ExOne BS004 produced by ExOne Corporation of the United States.

[0119] (4) Thermosetting and Vacuum Sintering: After 3D printing, the entire chamber is thermoset to enhance structural stability (thermosetting temperature is 120℃, time is 6h), and then the printed green body is sintered under a vacuum of less than 10℃. -2 In the Pa sintering furnace, segmented heating sintering is carried out. During the sintering process, the temperature is first held at 400℃ for 4 hours, then held at 900℃ for 3 hours, and finally held at 1000℃ for 4 hours to obtain high-performance alloy components with low carbon content and high density.

[0120] The mechanical properties of the alloy (i.e., a low-carbon, high-density high-performance alloy component) formed by binder jet 3D printing using this method are as follows: yield strength 717 MPa, tensile strength 854 MPa, and elongation 19.3%. The density of the low-carbon, high-density high-performance alloy component was tested using the drainage method (conducted according to the method described in ASTM Standard B962-15), and the density was 99.02%. Furthermore, the residual carbon content of this low-carbon, high-density high-performance alloy component is 0.005%, less than 0.01 wt%.

[0121] As can be seen from the above embodiments and comparative examples, the 3D printing method provided by the embodiments of the present invention has the following advantages:

[0122] (1) The structural design has a significant effect on optimizing the gas diffusion path: The embodiment adopts a core-shell structure model and designs the shell thickness according to the geometric characteristics of the components, establishing an effective gas dissipation path, which is conducive to the smooth escape of the pyrolysis products of the shell binder and significantly reduces the phenomenon of residual carbon enrichment; while Comparative Example 1 adopts a homogeneous solid structure, which is prone to local carbon retention and pore defects in the thick-walled area.

[0123] (2) Differentiated spraying parameters improve density and structural integrity: In the embodiment, the high-saturation binder spraying strategy in the shell region improves the bonding strength in the early stage of forming and the subsequent dense sintering ability, forming a dense and stable shell. At the same time, the low saturation setting in the core region takes into account both exhaust efficiency and internal structure shape preservation. In contrast, the single saturation spraying control in Comparative Example 1, which is located in a porous path or thick-walled area, is difficult to simultaneously meet the requirements of carbon removal and densification.

[0124] (3) Significant improvement in mechanical properties: Compared with Comparative Example 1, the yield strength of the component obtained in Example 1 increased by nearly 5%, the tensile strength increased by more than 35%, and the elongation jumped from 2.3% to 18.1%. This shows that the 3D printing method provided by the present invention significantly improves the plasticity, ductility and fracture toughness of the material without sacrificing the strength index, demonstrating that the present invention has the ability to optimize both strength and plasticity at the same time.

[0125] (4) Excellent residual carbon control. The 3D printing method provided in this embodiment of the invention is suitable for high carbon sensitive systems: the combination of core-shell structure model and partitioned differentiated spraying binder can effectively reduce carbon residue, which helps to meet the stringent requirements of high carbon sensitive alloys for low residual carbon process and avoid problems such as intergranular precipitation or microstructure embrittlement caused by carbon enrichment.

[0126] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A 3D printing method for high-performance alloy components with low carbon content and high density, characterized in that, Includes the following steps: (1) The high carbon sensitive alloy powder is dried to obtain the dried high carbon sensitive alloy powder; (2) Design a core-shell structure model according to the required component structure, load the dried high carbon sensitive alloy powder described in step (1) into the powder hopper of 3D printing, and perform 3D printing; (3) The printed components described in step (2) are subjected to thermosetting and sintering treatment to obtain high-performance alloy components with low carbon content and high density. The high carbon sensitive alloy powder mentioned in step (1) is a NiCoCr series high entropy alloy powder; the high carbon sensitive alloy powder is graded and sieved before use so that the particle size of the high carbon sensitive alloy powder is controlled below 50 μm. The drying temperature in step (1) shall not exceed 200℃, and the drying time shall be 1~3h; the drying process shall be carried out under a vacuum degree of less than 30Pa. In step (2), the core-shell structure model includes a shell region and a core region. During the 3D printing process, the saturation of the binder in the shell region is controlled at 80-100%, and the saturation of the binder in the core region is controlled at 0%. The shell is divided into a distal nucleus region and a proximal nucleus region. The distal nucleus region is connected to the proximal nucleus region, and the proximal nucleus region is connected to the nucleus region. The thickness of the proximal nucleus region is 1 mm. The binder saturation of the proximal nucleus region is controlled at 80%, and the binder saturation of the distal nucleus region is controlled at 100%. The adhesive used in the 3D printing in step (2) is at least one of ExOne BA005 and ExOne BS004; In the core-shell structure model described in step (2), the shell region has a thickness of 3 mm; both the core region and the shell region are solid structures; during the 3D printing process, the forming density of the core region and the shell region remains consistent. The sintering process is segmented sintering; the sintering process is carried out under a vacuum degree lower than 10. -2 The sintering process is carried out in a Pa sintering furnace; the sintering process includes the following steps: first, holding at 400~900℃ for 0.5~4h, then holding at 900~1000℃ for 0.5~3h, and finally holding at 1000~1500℃ for 1~4h.

2. The 3D printing method for low-carbon, high-density, high-performance alloy components according to claim 1, characterized in that, The 3D printing method described in step (2) is binder jet 3D printing; the 3D printing is performed layer by layer using the following parameters: powder bed temperature is 30-70℃, single layer drying time is 3-15 s, powder spreading roller rotation speed is 200-380 rpm, single layer powder thickness is 50-150 μm, and powder spreading speed is 1-15 mm / s.

3. The 3D printing method for low-carbon, high-density, high-performance alloy components according to claim 1, characterized in that, The thermosetting process in step (3) includes: heating the 3D-printed powder hopper to 120~350℃ and holding it at that temperature for 1~6 hours to obtain a green blank that has undergone thermosetting.

4. A high-performance alloy component with low carbon content and high density prepared by the 3D printing method according to any one of claims 1-3, characterized in that, The residual carbon content is less than 0.01 wt%, and the density is ≥98%.

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