3D printing metal material and modification method thereof

Abstract

The application provides a 3D printing metal material and a modification method thereof, and relates to the technical field of metal modification. The modification method of the 3D printing metal material provided by the application takes laser 3D printing metal titanium / titanium alloy as an initial material, forms a wrapping material and an encapsulation layer in sequence to obtain a synthetic block, and then obtains a strong and tough 3D printing metal titanium through a direct high-pressure treatment process. This is because the ultrahigh pressure can inhibit the long-range diffusion of atoms and avoid the coarsening of crystal grains at high temperatures; meanwhile, the high pressure can cause the grain refinement of the metal titanium / titanium alloy, thereby improving the strength thereof; the high pressure can repair the defects such as holes and microcracks in the metal component; under high temperature and high pressure, more strengthening defect structures such as dislocations and twins can be generated in the metal component; the high-temperature heat treatment under high pressure can eliminate the distribution of residual stress and uneven phases and improve the ductility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal modification, and particularly relates to a 3D printing metal material and a modification method thereof. BACKGROUND

[0002] Titanium and titanium alloy is a high-performance metal material, which has a series of remarkable advantages, such as light weight and high strength, which makes titanium and titanium alloy become an ideal material for manufacturing components that need light weight and high strength; corrosion resistance, excellent corrosion resistance to various acids, alkalis, salts and other corrosive media, can be used in harsh chemical environment for a long time without corrosion; good biocompatibility and good plasticity and processability. In short, titanium and titanium alloy is widely used in aerospace, chemical equipment, automobile manufacturing, medical devices and many other fields, and plays an increasingly important role in modern industry and technological development.

[0003] 3D printing technology, also known as additive manufacturing, is a technology that builds three-dimensional solid objects by layering materials. Through digital control of the accumulation path, it can directly manufacture complex components. Because of its free-forming ability, it fully meets the needs of high-end equipment and components for high integration, multi-functionality, light weight and integration, and is considered a disruptive technology in the manufacturing field. Compared with traditional manufacturing, 3D printing technology has the advantages of strong manufacturing capability of complex structure, high material utilization rate, high design flexibility and high production efficiency. Due to the excellent performance of titanium / titanium alloy and the advancement of 3D printing technology, the use of 3D printing to prepare titanium components and products has great demand in the fields of aerospace, military and biomedicine.

[0004] However, due to the technical limitations of existing 3D printing, the metal materials prepared by 3D printing still have deficiencies, which seriously restrict their widespread application as structural load-bearing components.

[0005] The deficiencies of 3D printing are: 1. It is currently almost impossible to achieve samples without micropores; 2. The inhomogeneous distribution of phases and strong textured columnar crystal structure reduces the mechanical properties of the material and also leads to anisotropy; 3. The 3D printed metal parts have cracks and high residual stress. Residual stress and anisotropy of microstructure can affect the performance of the material.

[0006] Traditional post-processing methods usually improve the ductility of metal material components, but also reduce their strength, making it difficult to obtain metal materials with both strength and toughness. The heat treatment process is complex and has a long cycle. Vacuum heat treatment can eliminate micropores, but this usually leads to changes in the microstructure, such as the growth of beta grains, the fragmentation of unique layered needle-like morphology, etc. Hot isostatic pressing can repair microcracks, but will lead to grain coarsening and the precipitation of unfavorable phases, thereby weakening the mechanical properties of the material. SUMMARY

[0007] The present application aims to provide a 3D printing metal material and a modification method thereof, and aims to solve the problem that the existing post-processing means is difficult to obtain a metal material with good strength and toughness.

[0008] To achieve the above object, the present application provides a modification method of a 3D printing metal material, comprising:

[0009] placing an initial 3D printing sample into a wrapping material for pre-press forming to obtain a blank;

[0010] forming an encapsulation layer outside the blank to obtain a synthesis block, and baking;

[0011] treating the baked synthesis block at a pressure of 1GPa-6GPa and a temperature of room temperature-500℃ for 1min-60min to obtain a 3D printing metal material with high strength and toughness.

[0012] In some embodiments, the treating the baked synthesis block at a pressure of 1GPa-6GPa and a temperature of room temperature-500℃ for 1min-60min is performed three times.

[0013] In some embodiments, the pressure increasing rate and the pressure decreasing rate of the pressure are independently 5GPa / h-20GPa / h; and the temperature increasing rate and the temperature decreasing rate of the temperature are independently 10℃ / min-300℃ / min.

[0014] In some embodiments, the pre-press forming pressure is 100MPa-500MPa, and the pressure application time is 1s-20s.

[0015] In some embodiments, the baking temperature is 120-220℃.

[0016] In some embodiments, the wrapping material is selected from any one of hexagonal boron nitride, magnesium oxide, NaCl, and CsCl; and the purity of the wrapping material is greater than 99%.

[0017] In some embodiments, the encapsulation layer comprises a heating material, a heat preservation material, and a pressure transmission medium which are nested in sequence; and the encapsulation layer further comprises a conductive cap arranged on the pressure transmission medium and connected to the heating material.

[0018] In some embodiments, at least one of the following conditions is met:

[0019] A. The heating material is a graphite tube material;

[0020] B. The heat preservation material is selected from any one of dolomite tube, zirconia, rhenium chromate tube, and zirconia doped with calcium oxide tube;

[0021] C. The pressure transmitting medium is pyrophyllite;

[0022] D. The conductive cap comprises any one of a copper column, an iron column, a molybdenum column, and a graphite column.

[0023] The application also provides a 3D printing metal material prepared by the modification method of the 3D printing metal material.

[0024] In some embodiments, the 3D printing metal material has a strength of 1000 MPa to 1100 MPa and an elongation of 5% to 20%.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] The modification method of the 3D printing metal material provided by the application takes laser 3D printing titanium / titanium alloy as the initial material, sequentially forms a wrapping material and an encapsulation layer to obtain a synthesis block, and then obtains a strong and tough 3D printing titanium through a direct high-pressure treatment process. This is because the ultrahigh pressure can inhibit the long-range diffusion of atoms and avoid the coarsening of grains at high temperatures. At the same time, the high pressure can cause grain refinement in the titanium / titanium alloy, thereby improving the strength thereof. The high pressure can repair defects such as pores and microcracks in the metal member. Under high temperature and high pressure, more strengthening defect structures such as dislocations and twins can be generated in the metal member. High-temperature heat treatment under high pressure can eliminate the distribution of residual stress and inhomogeneous phases and improve the ductility.

[0027] The modification method of the 3D printing metal material provided by the application simplifies the process flow and removes the complex heat treatment process. Compared with the traditional heat treatment lasting for several hours, the method can be completed within one hour, thereby shortening the production time, reducing the production cost, and facilitating large-scale production. The strong and tough titanium prepared by the method has both improved strength and ductility, thereby solving the problem of insufficient performance of existing metal members and having a wide range of applications.

[0028] The 3D printing metal material provided by the application has both strength and toughness, and the strength can reach 1000 MPa to 1100 MPa and the elongation can reach 5% to 20%. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope of the application.

[0030] Figure 1 FIG. 1 is a flowchart of the modification method of the 3D printing metal material of the application;

[0031] Figure 2 FIG. 2 is a structural diagram of the synthesis block of the application.

[0032] Figure 3 This is a comparison diagram of the tensile properties of the 3D-printed titanium metal components before and after ultra-high pressure modification in this application;

[0033] Figure 4 The images are scanning electron microscope images of the 3D printed titanium metal component in Example 1 before and after high pressure treatment.

[0034] Figure 5 The image shows electron backscatter diffraction patterns of the 3D-printed titanium metal component in Example 1 before and after high-pressure treatment.

[0035] Figure label:

[0036] 10 - Initial 3D printed sample; 20 - Wrapping material; 30 - Heating material; 40 - Thermal insulation material; 50 - Pressure transmission medium; 60 - Conductive cap. Detailed Implementation

[0037] As used in this article:

[0038] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0039] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0040] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0041] In these embodiments, the parts and percentages are by mass unless otherwise indicated.

[0042] "Mass parts" refers to a basic unit of measurement that represents the mass ratio relationship of multiple components, 1 part can represent any unit mass, such as 1 g, 2.689 g, etc. If we say that the mass of component A is a parts, and the mass of component B is b parts, it means that the mass ratio of component A to component B is a:b. Alternatively, it means that the mass of component A is aK, and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that unlike mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0043] "And / or" is used to indicate that one or both of the described cases can occur, for example, A and / or B includes (A and B) and (A or B).

[0044] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0045] The present application provides a modification method of 3D printed metal material, please refer to Figure 1 , comprising:

[0046] S100: Put the initial 3D printed sample into the wrapping material for pre-press forming to obtain a blank;

[0047] S200: Form an encapsulation layer outside the blank to obtain a synthesis block, and perform baking;

[0048] S300: Treat the baked synthesis block at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500°C for 1 min to 60 min to obtain a strong and tough 3D printed metal material.

[0049] The present application takes a laser 3D printed sample as the initial material, forms a wrapping material and an encapsulation layer outside the initial 3D printed sample in turn to obtain a synthesis block, and then obtains a strong and tough 3D printed titanium metal through a direct high-pressure treatment process. This is because ultra-high pressure can inhibit the long-range diffusion of atoms and avoid grain coarsening at high temperatures; at the same time, high pressure can cause grain refinement inside the titanium metal / titanium alloy, thereby improving its strength; high pressure can repair defects such as pores and micro-cracks inside the metal component; under high temperature and high pressure, more strengthening defect structures such as dislocations and twins can be generated inside the metal part; high-temperature heat treatment under high pressure can eliminate residual stress and the distribution of inhomogeneous phases, and improve ductility.

[0050] In some embodiments, the 3D printed sample in step S100 is a 3D printed metal titanium / titanium alloy component, and the wrapping material is selected from any one of hexagonal boron nitride, magnesium oxide, NaCl, and CsCl; the purity of the wrapping material is greater than 99%. The wrapping material is a material with good hydrostatic pressure (fluid or quasi-fluid state at high temperature and high pressure) and stable performance.

[0051] In some embodiments, the pre-pressing forming pressure in step S100 is 100 MPa to 500 MPa, for example, 100 MPa, 200 MPa, 300 MPa, 400 MPa, 500 MPa, or any value between 100 MPa and 500 MPa, and the pressure application time is 1 s to 20 s, for example, 1 s, 5 s, 10 s, 15 s, 20 s, or any value between 1 s and 20 s.

[0052] In some embodiments, the packaging layer in step S200 comprises a heating material, a heat preservation material, and a pressure transmission medium nested in sequence; and the packaging layer further comprises a conductive cap arranged on the pressure transmission medium and connected to the heating material.

[0053] In some embodiments, the heating material is a graphite tube material.

[0054] In some embodiments, the heat preservation material is selected from any one of dolomite tube, zirconia, rhenium chromate tube, and zirconia doped with calcium oxide tube.

[0055] In some embodiments, the pressure transmission medium is pyrophyllite.

[0056] In some embodiments, the conductive cap comprises any one of a copper column, an iron column, a molybdenum column, and a graphite column.

[0057] Please refer to Figure 2 , Figure 2 FIG. 2 is a structural schematic diagram of a synthetic block in step S200, wherein 10 is an initial 3D printed sample, 20 is a wrapping material, 30 is a heating material, 40 is a heat preservation material, 50 is a pressure transmission medium, and 60 is a conductive cap.

[0058] In an embodiment of the present application, the initial 3D printed sample 10 is a 3D printed metal titanium component, the wrapping material 20 is hexagonal boron nitride, the heating material 30 is a graphite tube material, the heat preservation material 40 is a dolomite tube, the pressure transmission medium 50 is pyrophyllite, and the conductive cap 60 is a molybdenum column.

[0059] In some embodiments, the baking temperature in step S200 is 120-220°C, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, or any value between 120°C and 220°C.

[0060] In some embodiments, the pressure in step S200 can be, for example, 1 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, or any value between 1 GPa and 6 GPa, the temperature can be, for example, room temperature, 100℃, 200℃, 300℃, 400℃, 500℃, or any value between room temperature and 500℃, and the processing time can be, for example, 1 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or any value between 1 min and 60 min.

[0061] In some embodiments, the number of times of processing the baked synthesis block in step S300 at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500℃ for 1 min to 60 min is three.

[0062] In some embodiments, the pressure increasing rate and the pressure decreasing rate in step S300 are independently 5 GPa / h to 20 GPa / h, for example, 5 GPa / h, 10 GPa / h, 15 GPa / h, 20 GPa / h, or any value between 5 GPa / h and 20 GPa / h.

[0063] In some embodiments, the temperature increasing rate and the temperature decreasing rate in step S300 are independently 10℃ / min to 300℃ / min, for example, 10℃ / min, 50℃ / min, 100℃ / min, 150℃ / min, 200℃ / min, 250℃ / min, 300℃ / min, or any value between 10℃ / min and 300℃ / min. If the temperature increasing rate is too low, the processing period is too long; if the temperature increasing rate is too high, the stability and safety of the equipment are easily affected.

[0064] The application also provides a 3D printing metal material prepared by the modification method of the 3D printing metal material described above.

[0065] The 3D printing metal material provided by the application has both strength and toughness, the strength can reach 1000 MPa to 1100 MPa, and the elongation can reach 5% to 20%.

[0066] The embodiments of the application will be described in detail below with specific examples, but those skilled in the art will understand that the following examples are only for illustration of the application and should not be regarded as limiting the scope of the application. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be purchased on the market.

[0067] In the following examples and comparative examples, the large cavity static high pressure device is a domestic hinged six-surface press, model DS6x 36MN, and the metal titanium / titanium alloy components used are all prepared by laser 3D printing equipment.

[0068] In the following examples and comparative examples, the heating material is graphite tube material, the heat preservation material is dolomite tube, and the pressure transmission medium is pyrophyllite.

[0069] Example 1

[0070] The present embodiment provides a modification method of 3D printed metal material, the steps of which include:

[0071] (1) Initial sample preparation

[0072] In the selected laser melting (SLM) printing equipment, 15-53 micron pure titanium powder is hung in the forming area, the program text of the required printed metal part cylindrical block is input in the control system, the laser power is set at about 150W and the scanning interval is about 100 microns, and after melting and solidification, the powder is printed again, and the printing forming of the component is realized by repeated multiple times.

[0073] (2) Package selection

[0074] Hexagonal boron nitride powder is selected as the package material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0075] (3) Pre-pressing forming

[0076] The metal titanium component processed in step (1) is placed in the package material purified in step (2) for pre-pressing forming, so that the package material fills around the metal titanium component, and a pre-pressing formed blank is obtained, the pre-pressing pressure is 300MPa, and the pressure holding time is 20 seconds.

[0077] (4) Synthesis block baking

[0078] The pre-pressing formed blank is placed in the nested pressure transmission medium, heat preservation material and heating material to form a synthesis block, and the synthesis block is baked in a muffle furnace or oven at 120°C for 10 minutes.

[0079] (5) High temperature and high pressure treatment and removal of the package

[0080] The baked synthesis block is directly placed in a high temperature and high pressure device, the pressure is increased from atmospheric pressure to 5GPa at a rate of 15GPa / h, and then the pressure is kept constant, the high pressure treatment is carried out at a pressure of 5GPa and a temperature of room temperature for 10 minutes, after the treatment time, the pressure is decreased to atmospheric pressure at a rate of 12GPa / h, and then the surface adsorbed impurities are removed by alcohol and deionized water ultrasonic, thereby obtaining the strong and tough 3D printed metal titanium component of Example 1.

[0081] The strong and tough 3D printed metal titanium component of Example 1 is tested for tensile strength, which is improved from an initial 700 MPa to 1050 MPa, and elongation, which is improved from 1% to 12%, as shown in Figure 3 FIG. 1. Figure 4 FIG. 2 is a scanning electron microscope image of a 3D printed metal titanium component before and after 5 GPa high pressure treatment. Figure 5 FIG. 3 is an electron backscatter diffraction image of a 3D printed metal titanium component before and after 5 GPa high pressure treatment. As can be seen, there are a large number of holes, cracks, and uneven structures in the 3D printed metal titanium before ultra-high pressure treatment Figure 4 (left side part a), and there are obvious columnar crystals of large size Figure 5 (left side part c). After ultra-high pressure modification treatment, the internal holes and cracks are repaired Figure 4 (right side part b), and the grains are refined and homogenized under high pressure Figure 5 (right side part d), improving the mechanical properties of titanium.

[0082] Example 2

[0083] The present embodiment provides a modification method for a 3D printed metal material, the steps of which include:

[0084] (1) Initial sample preparation

[0085] In a selected laser melting (SLM) printing device, 15-53 micron pure titanium powder is hung in the forming area, the program text of the required printed metal component cylindrical block is input in the control system, the laser power is set to about 150 W and the scanning interval is about 100 microns, and after melting and solidification, the powder is printed again, and the printing forming of the component is realized by repeated multiple times.

[0086] (2) Wrapping selection

[0087] Hexagonal boron nitride powder is selected as the wrapping material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0088] (3) Pre-pressing forming

[0089] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing forming, so that the wrapping material fills around the metal titanium component, and a pre-pressing formed blank is obtained, the pre-pressing pressure is 300 MPa, and the pressure holding time is 20 seconds.

[0090] (4) Synthesis block baking

[0091] The pre-pressing formed blank is placed in the nested pressure transmission medium, heat preservation material and heating material to form a synthesis block, and the synthesis block is baked in a muffle furnace or oven at 120°C for 10 minutes.

[0092] (5) High temperature and high pressure treatment and removal of inclusions

[0093] The roasted synthesis block is directly placed into a high temperature and high pressure device, first raised to 5 GPa from normal pressure at a pressure increasing rate of 15 GPa / h, then raised to 500°C at a temperature increasing rate of 100°C / min and kept for 30 min, after the treatment time, first reduced to normal temperature at a temperature decreasing rate of 100°C / min, then reduced to normal pressure at a pressure decreasing rate of 13 GPa / h, then the surface adsorbed impurities are removed by alcohol and deionized water ultrasonic, thereby obtaining the strong and tough 3D printed metal titanium of Example 2.

[0094] The strong and tough 3D printed metal titanium of Example 2 is subjected to tensile test, the strength is increased from the initial 700 MPa to 1000 MPa, the elongation is increased from 1% to 19%, as shown in Figure 3 , the mechanical properties of titanium are greatly improved.

[0095] Example 3

[0096] The embodiment provides a modification method of 3D printed metal material, the steps of which comprise:

[0097] (1) Initial sample preparation

[0098] In a selected laser melting (SLM) printing device, 15-53 micron pure titanium powder is hung to a forming area, a program text of a required printed metal piece cylindrical block is input in a control system, a laser power is set to about 150 W and a scanning interval is set to about 100 microns, after melting and solidification, powder laying is performed again, and the printing forming of the component is realized by repeated multiple times.

[0099] (2) Inclusion selection

[0100] Magnesium oxide powder is selected as the inclusion material to provide a hydrostatic pressure environment, and drying and purification treatment is performed before use to remove moisture and impurities.

[0101] (3) Pre-pressing forming

[0102] The metal titanium component processed in step (1) is placed into the inclusion material purified in step (2) to pre-press and form, so that the inclusion material is filled around the metal titanium component, thereby obtaining a pre-pressing formed blank, the pre-pressing pressure is 200 MPa, and the pressure holding time is 15 seconds.

[0103] (4) Synthesis block roasting

[0104] The pre-pressing formed blank is placed into nested pressure transmission medium, heat preservation material and heating material to form a synthesis block, and the synthesis block is roasted at 150°C in a muffle furnace or an oven for 10 minutes.

[0105] (5) High temperature and high pressure treatment and removal of the coating

[0106] The roasted synthetic block is directly put into a high temperature and high pressure device, first raised to 3 GPa from normal pressure at a pressure increasing rate of 10 GPa / h, then heated to 500℃ at a heating rate of 100℃ / min and kept for 30 min, after the treatment time, first reduced to normal temperature at a temperature decreasing rate of 100℃ / min, then reduced to normal pressure at a pressure decreasing rate of 10 GPa / h, then the surface adsorbed impurities are removed by alcohol and deionized water ultrasonic, thus the strong and tough 3D printed metal titanium of example 3 is obtained.

[0107] The strong and tough 3D printed metal titanium of example 3 is tested by tensile test, the strength is increased from the initial 750 MPa to 1000 MPa, the elongation is increased from 1% to 5%, as shown in Figure 3 , the mechanical properties of titanium are greatly improved.

[0108] Example 4

[0109] The embodiment provides a modification method of 3D printed metal material, the steps of which include:

[0110] (1) Initial sample preparation

[0111] In the selected laser melting (SLM) printing equipment, 15-53 micron pure titanium powder is hung in the forming area, the program text of the required printed medical titanium tooth is input in the control system, the laser power is set to about 150 W and the scanning interval is about 100 microns, after melting and solidification, the powder is printed again, and the printing forming of the component is realized by repeated multiple times.

[0112] (2) Coating selection

[0113] The hexagonal boron nitride powder is selected as the coating material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0114] (3) Pre-pressing forming

[0115] The metal titanium component processed in step (1) is put into the coating material purified in step (2) for pre-pressing forming, so that the coating material is filled around the metal titanium component, and a pre-pressing blank is obtained, the pre-pressing pressure is 300 MPa, and the pressure holding time is 20 seconds.

[0116] (4) Roasting of synthetic block

[0117] The pre-pressing blank is put into the nested pressure transmission medium, heat preservation material and heating material to form a synthetic block, and the synthetic block is roasted at 120℃ for 10 minutes in a muffle furnace or an oven.

[0118] (5) High temperature and high pressure treatment and removal of the coating

[0119] The baked synthesis block is directly placed into a high-temperature and high-pressure device, and is subjected to ultra-high pressure treatment under the condition that the pressure is increased to 5 GPa at a pressure increasing rate of 15 GPa / h and the temperature is room temperature, and then the pressure is decreased to the normal pressure at a pressure decreasing rate of 12 GPa / h, and then the pressure is increased to 5 GPa again, and the ultra-high pressure treatment is performed for three cycles. Then, the surface adsorbed impurities are removed by ultrasonic treatment with alcohol and deionized water, and thus the strong and tough 3D printed metal titanium tooth is obtained.

[0120] After the ultra-high pressure treatment, the holes and cracks in the titanium tooth are repaired, and the grains are refined and homogenized under high pressure, and thus the mechanical properties of the titanium are improved. The strength of the strong and tough 3D printed metal titanium component of Example 4 is increased from 700 MPa to 1100 MPa, and the elongation is increased from 1% to 7% after the tensile test, and compared with the single high pressure treatment, the strength is slightly increased, but the elongation is slightly decreased.

[0121] Example 5

[0122] The embodiment provides a modification method of a 3D printed metal material, and the steps of the method include:

[0123] (1) Initial sample preparation

[0124] In a selected laser melting (SLM) printing device, 15-53 micron pure titanium powder is hung in a forming area, a program text required for printing a medical titanium tooth is input in a control system, a laser power is set to be about 150 W and a scanning interval is set to be about 100 microns, and after melting and solidification, powder laying is performed again, and the printing forming of the component is realized by repeating multiple times.

[0125] (2) Package selection

[0126] Hexagonal boron nitride powder is selected as a package material to provide a hydrostatic pressure environment, and before use, drying and purification treatment are performed to remove water and impurities.

[0127] (3) Pre-pressing forming

[0128] The metal titanium component processed in step (1) is placed into the package material purified in step (2) to be pre-pressed and formed, so that the package material is filled around the metal titanium component, and a pre-pressed blank body is obtained, and the pre-pressing pressure is 300 MPa, and the pressure holding time is 20 seconds.

[0129] (4) Synthesis block baking

[0130] The pre-pressed blank body is placed into nested pressure transmission media, heat preservation materials and heating materials to form a synthesis block, and the synthesis block is baked at 120 DEG C for 10 minutes in a muffle furnace or an oven.

[0131] (5) High temperature and high pressure treatment and removal of the coating

[0132] The baked synthesis block is directly placed into a high temperature and high pressure device, and is subjected to high pressure treatment at a temperature of room temperature for 10 min after being raised to 3 GPa at a pressure raising rate of 15 GPa / h, and then the pressure is reduced to normal pressure at a pressure reducing rate of 12 GPa / h. Then, the surface adsorbed impurities are removed by ultrasonic treatment with alcohol and deionized water, thereby obtaining a strong and tough 3D printed metal titanium tooth.

[0133] After the high pressure treatment, the holes and cracks in the titanium tooth are repaired, and the grains are refined and homogenized under high pressure, thereby improving the mechanical properties of the titanium. The strength of the strong and tough 3D printed metal titanium component of Example 5 is improved from 700 MPa to 1050 MPa after the tensile test, and the elongation is also obviously improved compared with before the treatment, as shown in Figure 3 .

[0134] Comparative Example 1

[0135] The present comparative example provides a modification method of a 3D printed metal material, and the steps include:

[0136] (1) Preparation of an initial sample

[0137] In a selected laser melting (SLM) printing device, 15-53 micron pure titanium powder is hung in a forming area, a program text required for printing a cylindrical block of a metal part is input into a control system, a laser power is set to about 150 W and a scanning interval is set to about 100 microns, and after melting and solidification, powder laying is performed again, and the printing of the component is realized by repeated implementation.

[0138] (2) Coating selection

[0139] Hexagonal boron nitride powder is selected as a coating material to provide a hydrostatic pressure environment, and is subjected to drying and purification treatment before use to remove moisture and impurities.

[0140] (3) Pre-pressing

[0141] The metal titanium component processed in step (1) is placed into the coating material subjected to the purification treatment in step (2) to be pre-pressed, so that the coating material is filled around the metal titanium component, and a pre-pressed blank is obtained, and the pre-pressing pressure is 300 MPa and the pressure holding time is 20 seconds.

[0142] (4) Baking of the synthesis block

[0143] The pre-pressed blank is placed into nested pressure transmission media, heat preservation materials and heating materials to form a synthesis block, and the synthesis block is baked at 120°C for 10 min in a muffle furnace or an oven.

[0144] (5) High temperature and high pressure treatment and removal of the coating

[0145] The baked synthesis block is directly placed into a high-temperature high-pressure device, and the pressure is increased to 5 GPa at a rate of 15 GPa / h, then the pressure is kept constant, and the temperature is increased to 1000°C at a rate of 100°C / min and kept constant for 30 min. After the treatment time, the temperature is first decreased to room temperature at a rate of 100°C / min, and then the pressure is decreased to atmospheric pressure at a rate of 13 GPa / h. Then the surface adsorbed impurities are removed by alcohol and deionized water ultrasonic, and the titanium tensile piece of Comparative Example 1 is obtained.

[0146] The tensile test strength of the titanium tensile piece of Comparative Example 1 remains essentially unchanged from the initial 700 MPa, and the elongation rate increases from 1% to 4%. This is mainly due to the fact that the temperature is too high, causing the grains to coarsen significantly and reducing the mechanical properties. Even if the holes and cracks are eliminated under high pressure, the strength does not increase significantly. When the set temperature does not match, the strength and ductility cannot be improved simultaneously.

[0147] Comparative Example 2

[0148] The present comparative example provides a modification method of 3D printed metal material, the steps of which include:

[0149] (1) Initial sample preparation

[0150] In the selected laser melting (SLM) printing equipment, 15-53 micron pure titanium powder is hung in the forming area, the program text of the required printed metal piece cylindrical block is input in the control system, the laser power is set to about 150 W and the scanning pitch is about 100 microns, and after melting and solidification, the powder is printed again, and the printing forming of the component is realized by repeated multiple times.

[0151] (2) High-temperature annealing treatment

[0152] The printed titanium metal piece is placed in a vacuum tube furnace and vacuum annealed at a temperature of 800°C for 30 min. After the treatment time, the temperature is decreased to room temperature. Then the surface adsorbed impurities are removed by alcohol and deionized water ultrasonic, and the treated titanium tensile piece of Comparative Example 2 is obtained.

[0153] The treated titanium tensile piece of Comparative Example 2 has a tensile test strength of 600 MPa, which is lower than the initial 700 MPa, and an elongation rate of 0.5%, which is lower than the initial 1%. This is mainly due to the fact that the simple temperature annealing treatment cannot repair the holes and cracks in the metal titanium. When the temperature is too high, the grains coarsen significantly, reducing the mechanical properties.

[0154] Comparative Example 3

[0155] The present comparative example provides a modification method of 3D printed metal material, the steps of which include:

[0156] (1) Initial sample preparation

[0157] In a selective laser melting (SLM) printing device, 15-53 micron pure titanium powder was hung in the forming area, the program text of the required printed metal part cylinder block was input in the control system, the laser power was set at about 150 W and the scanning interval was about 100 microns, and after melting and solidification, powder printing was performed again, and repeated multiple times to realize the printing forming of the component.

[0158] (2) Package selection

[0159] Hexagonal boron nitride powder was selected as the package material to provide a hydrostatic pressure environment, and was dried and purified before use to remove moisture and impurities.

[0160] (3) Pre-pressing

[0161] The metal titanium component processed in step (1) was placed in the package material purified in step (2) for pre-pressing, so that the package material filled around the metal titanium component, and a pre-pressed blank was obtained. The pre-pressing pressure was 300 MPa, and the pressure holding time was 20 seconds.

[0162] (4) Synthesis block baking

[0163] The pre-pressed blank was placed in the nested pressure transmission medium, heat preservation material and heating material to form a synthesis block, and the synthesis block was baked at 120°C for 10 minutes in a muffle furnace or oven.

[0164] (5) High temperature and high pressure treatment and removal of the package

[0165] The baked synthesis block was directly placed in a high temperature and high pressure device, and the pressure was increased from atmospheric pressure to 5 GPa at a rate of 15 GPa / h, then the temperature was increased to 700°C at a rate of 100°C / min and held for 30 min, after the treatment time, the temperature was first decreased to room temperature at a rate of 100°C / min, and then the pressure was decreased to atmospheric pressure at a rate of 13 GPa / h. Then use alcohol and deionized water to remove the surface adsorbed impurities to obtain the titanium tensile part of Comparative Example 3.

[0166] The titanium tensile part of Comparative Example 3 had a tensile test strength of 700 MPa, which remained essentially unchanged, and an elongation of 1% to 2%, which was mainly due to the fact that the temperature was too high, causing the grains to coarsen significantly, reducing the mechanical properties, even though the holes and cracks were eliminated under high pressure, the strength did not increase significantly. When the temperature is not matched, the strength and ductility cannot be improved simultaneously.

[0167] Finally, it should be noted that the above-described embodiments are merely intended for describing and illustrating, but not limiting the technical solutions of the present application; even though the present application has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the above embodiments, or equivalently replace some or all of the technical features thereof; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0168] Furthermore, those skilled in the art will appreciate that a combination of features from different embodiments can be meant to be within the scope of the present application and form a different embodiment, although some embodiments herein include certain features rather than others included in other embodiments. For example, in the claims above, any of the claimed embodiments can be used in any combination. The information disclosed in this Background section is only intended to deepen the understanding of the general background of the present application, and should not be considered as acknowledging or implying in any form that this information constitutes prior art known to those skilled in the art.

Claims

1. A method for modifying 3D printed metallic materials, characterized in that, include: The initial 3D printed sample is placed in the packaging material and pre-pressed to obtain the blank; An encapsulation layer is formed outside the blank to obtain a composite block, which is then baked. The baked composite block was treated at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500°C for 1 min to 60 min to obtain a tough 3D printed metal material. The process of treating the baked synthetic block under pressure of 1 GPa to 6 GPa and temperature of room temperature to 500°C for 1 min to 60 min is repeated three times. The coating material is selected from any one of hexagonal boron nitride, magnesium oxide, NaCl, and CsCl; the purity of the coating material is greater than 99%. The 3D printed metal material is pure titanium.

2. The method for modifying 3D printed metal materials according to claim 1, characterized in that, The pressure increase rate and pressure decrease rate are each independently 5 GPa / h to 20 GPa / h; the temperature increase rate and temperature decrease rate are each independently 10 °C / min to 300 °C / min.

3. The method for modifying 3D printed metal materials according to claim 1, characterized in that, The pressure of the pre-compression molding is 100 MPa to 500 MPa, and the pressure application time is 1s to 20s.

4. The method for modifying 3D printed metal materials according to claim 1, characterized in that, The baking temperature is 120~220℃.

5. The method for modifying 3D printed metal materials according to claim 1, characterized in that, The encapsulation layer includes a heating material, a heat-insulating material, and a pressure-transmitting medium nested in sequence; the encapsulation layer also includes a conductive cap disposed on the pressure-transmitting medium and connected to the heating material.

6. The method for modifying 3D printed metal materials according to claim 5, characterized in that, At least one of the following conditions must be met: A. The heating material is a graphite tube material; B. The thermal insulation material is selected from any one of dolomite pipe, zirconium oxide, rhenium chromate pipe, and zirconium oxide doped with calcium oxide pipe; C. The pressure-transmitting medium is pyrophyllite; D. The conductive cap includes any one of copper pillars, iron pillars, molybdenum pillars, and graphite pillars.

7. A 3D printing metal material, characterized in that, The 3D printing metal material is prepared by the modification method of any one of claims 1 to 6, wherein the 3D printing metal material is pure titanium.

8. The 3D printing metal material according to claim 7, characterized in that, The 3D printed metal material has a strength of 1000MPa~1100MPa and an elongation of 5%~20%.

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