Dissolvable stent

Abstract

The application discloses a metal type flux-cored wire for 3D printing of a duplex stainless steel flange structural member and a method. The flux-cored wire comprises the following components in percentage by mass: chromium powder 22-28%, titanium powder 1-2%, aluminum powder 2-4%, molybdenum powder 6-8%, copper powder 2-3%, niobium powder 5-7%, carbon powder 0.03%, manganese powder 1-2%, silicon powder 0.3-0.6%, chromium nitride 0.1-0.2%, and the rest is iron powder, and the sum of the percentages by mass of the above components is 100%. The duplex stainless steel structural member obtained by 3D printing is good in appearance, excellent in mechanical properties and good in corrosion resistance, and fully meets the use requirements of the flange structural member.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology of wire materials, specifically relating to a duplex stainless steel metal mold flux-cored welding wire and method for 3D printing flange structural parts. Background Technology

[0002] The "duplex" in duplex stainless steel refers to the presence of both austenite and ferrite in its microstructure. This microstructure allows duplex stainless steel to achieve a good balance between strength and corrosion resistance. This material has wide applications in the automotive industry, chemical equipment, marine engineering, and other fields, primarily in applications requiring high strength and excellent corrosion resistance.

[0003] Flange structural components are widely used in petrochemical, marine engineering, power equipment, and shipbuilding industries. These industries have extremely high requirements for the corrosion resistance, strength, and reliability of materials, especially in high-temperature, high-pressure, and highly corrosive environments, where ordinary materials are difficult to meet the requirements. Therefore, the selection of high-performance materials is particularly important.

[0004] Currently, 3D printing technology is widely used in the manufacture of complex structural parts because it can achieve geometric complexity and material utilization rates that are difficult to achieve with traditional manufacturing methods. Duplex stainless steel, as a high-performance material, is widely used in many industrial fields due to its excellent mechanical properties and superior corrosion resistance. However, due to its complex metallographic structure and high processing difficulty, producing duplex stainless steel parts, especially those with complex internal structures, using traditional manufacturing methods often faces challenges such as high cost, long lead times, and significant material waste.

[0005] Flux-cored welding wire is a special welding material consisting of an outer metal sheath encasing an inner layer of metal powder or other additives. During welding, flux-cored welding wire provides a more stable arc, better droplet transfer, and higher deposition efficiency. Furthermore, the chemical composition and properties of the weld metal can be controlled by adjusting the flux core composition. Applying our self-developed duplex stainless steel flux-cored welding wire to 3D printing technology, particularly for manufacturing flange structural components, offers several technological advantages: superior material properties, the flexibility of 3D printing technology, the advantages of flux-cored welding wire, cost-effectiveness, and the potential for technological innovation and industrial upgrading. Therefore, the application of our self-developed duplex stainless steel flux-cored welding wire in 3D printing flange structural components not only meets the market demand for high-performance, high-reliability components but also promotes technological innovation and industrial upgrading in related fields.

[0006] Currently, the existing technology for 3D printing of duplex stainless steel mainly uses commercial solid welding wire. There are no flux-cored wires specifically for arc 3D printing and remanufacturing of duplex stainless steel. Solid welding wire has a long manufacturing cycle, causes significant environmental pollution, and has limited material variety. The welding wires available on the market often fail to meet the requirements of 3D printing.

[0007] Therefore, how to develop a new type of duplex stainless steel flux-cored welding wire is a current problem. Summary of the Invention

[0008] The first objective of this invention is to provide a duplex stainless steel flux-cored welding wire that can be used as a raw material for 3D printing flange structural components. The preparation process of this flux-cored welding wire is simple and pollution-free, and its composition is easy to control.

[0009] A second objective of this invention is to provide a 3D printing method for duplex stainless steel structural components, specifically for 3D printing flange structural components.

[0010] The first technical solution adopted in this invention is: a duplex stainless steel flux-cored welding wire, comprising a flux core and an outer sheath, wherein the flux core is composed of the following components by mass percentage: 22-28% chromium powder, 1-2% titanium powder, 6-8% molybdenum powder, 2-3% copper powder, 5-7% niobium powder, 2-4% aluminum powder, 0.03% carbon powder, 1-2% manganese powder, 0.3-0.6% silicon powder, 0.1-0.2% chromium nitride, and the remainder being iron powder.

[0011] The outer sheath is made of 0Cr18Ni9 austenitic stainless steel strip, and the filling amount of the core powder is 20wt%-25wt%. (The composition is shown in Table 1).

[0012] The second technical solution adopted in this invention is a 3D printing method for duplex stainless steel structural parts, which is carried out according to the following steps: Step 1: Weigh the following raw materials according to their mass percentages: 22-28% chromium powder, 1-2% titanium powder, 6-8% molybdenum powder, 2-3% copper powder, 5-7% niobium powder, 2-4% aluminum powder, 0.03% carbon powder, 1-2% manganese powder, 0.3-0.6% silicon powder, 0.1-0.2% chromium nitride, and the remainder is iron powder. Step 2: Heat and keep warm the raw material powder weighed in Step 1 in an inert gas atmosphere to remove moisture; Step 3: Place the outer sheath on the feeding machine of the welding wire forming machine, and roll the outer sheath into a U-shaped groove through the pressing groove of the forming machine. After keeping the raw material powder obtained in Step 2 warm, cool it to room temperature in the furnace. Then fill the powder into the U-shaped groove. The filling rate of the flux core powder is controlled at 20wt%-25wt%. After passing through the closed forming roller, a 2.10mm welding wire is made. Finally, a 1.20mm metal mold flux core welding wire is made by gradually reducing the diameter. Step 4: Assemble the prepared metal-cored welding wire onto the fully automated welding robot, determine the layer height of each layer to be 2-3mm, write the corresponding program and input it into the welding robot, run the welding machine command, and use MIG welding as the heat source to 3D print the structural parts.

[0013] In step 2, the inert protective atmosphere is argon gas with a purity of 99.999%; in step 3, the outer sheath is 0Cr18Ni9 austenitic stainless steel strip.

[0014] In step 2, the heating temperature is 150~200℃ and the holding time is 2~2.5h.

[0015] In step 4, the process parameters for MIG welding are: welding speed 0.2m / min-0.3m / min; welding torch height 2mm-3mm for each layer; shielding gas 99.999% pure argon; and interpass cooling in step 4, with the interpass temperature controlled between 100℃ and 150℃.

[0016] The beneficial effects of this invention are: 1. The duplex stainless steel flux-cored welding wire of the present invention has a short preparation cycle and high production efficiency. Its performance can be improved by adjusting the composition and ratio of the flux core. At the same time, the production of flux-cored welding wire is pollution-free and the welding process has high cladding efficiency.

[0017] 2. The strengthening effect of the duplex stainless steel flux-cored welding wire of the present invention is achieved by adding a variety of precipitated phase elements to the welding wire, with Cr and Ni as the main alloying elements, and adding a certain amount of trace alloying elements such as Cu, Al, Mo, Nb, Ti, and CrN. At the same time, the proportion of each element is strictly controlled. The phase structure is predicted by Jmatpro thermodynamic software. When the ratio of ferrite to austenite is 1:1, the duplex steel has the best performance and can significantly improve mechanical properties.

[0018] 3. The present invention relates to a 3D printing method for duplex stainless steel structural parts, which uses MIG welding as a heat source and metal-cored welding wire as raw material to prepare duplex stainless steel using 3D printing technology. The present invention places uniformly mixed flux powder in a tube furnace, continuously introduces argon gas, and holds it at 150℃~200℃ for 2h~2.5h. The present invention uses a fully automated welding robot programmed to achieve 3D printing of duplex stainless steel structural parts, resulting in high efficiency. During the printing process, the arc is stable, the weld formation is aesthetically pleasing, the weld surface is smooth, and there are no pores or slag inclusions.

[0019] 4. The duplex stainless steel structural parts obtained by 3D printing according to this invention have beautiful shapes, excellent mechanical properties, and perfectly meet the requirements for flange use. Attached Figure Description

[0020] Figure 1 This is a stress-strain curve of duplex stainless steel prepared by the flux-cored welding wire in Example 4 of this invention; Figure 2 This is a microstructure diagram of Example 4 of the present invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] This invention provides a duplex stainless steel flux-cored welding wire, comprising a flux core and an outer sheath, wherein the flux core is composed of the following components by mass percentage: 22-28% chromium powder, 1-2% titanium powder, 6-8% molybdenum powder, 2-3% copper powder, 5-7% niobium powder, 2-4% aluminum powder, 0.03% carbon powder, 1-2% manganese powder, 0.3-0.6% silicon powder, 0.1-0.2% chromium nitride, and the remainder being iron powder.

[0023] The metal-cored welding wire of this invention offers simple composition control, more precise chemical composition range, and zero wastewater and exhaust gas emissions throughout the entire process. Its wide composition adjustment range makes it suitable for new material research and development, providing greater flexibility and easily meeting diverse performance requirements.

[0024] The functions and roles of each component in this welding wire are as follows: Cr (Cr): As one of the main alloying elements in duplex stainless steel, Cr plays an important role in improving the strength and corrosion resistance of weld overlay alloys. Cr can be incorporated into carbides (such as MnO2) in atomic form. 23 C6 atoms substitute for Fe atoms to form complex phases, such as (Fe,Cr)7C3 and (Fe,Cr). 23 C6, etc. Furthermore, the Cr element in the weld overlay alloy can dissolve in γ-Fe and α-Fe, improving the alloy's high-temperature strength and hardness, and enhancing the material's corrosion resistance.

[0025] Mo (Mo): When added within appropriate ranges, Mo helps promote the formation of a duplex (ferrite + austenite) structure. This not only improves the overall mechanical properties of the material but also enhances its corrosion resistance. The ferrite phase in the duplex structure improves the material's plasticity and toughness, while the austenite phase helps maintain high strength and corrosion resistance.

[0026] Ni (Ni): The alloying element Ni in steel strip can significantly inhibit the migration of carbon, effectively reduce the stability of carbides and the binding ability of carbide-forming elements to carbon, promote the formation of austenite and ferrite dual-phase structure, inhibit the growth of carbides, and improve the overall mechanical properties.

[0027] Cu element: Cu can enhance the strength and hardness of duplex stainless steel through solid solution strengthening effect. In particular, under appropriate heat treatment conditions, Cu element can regulate the phase transformation and microstructure formation of duplex stainless steel, and can optimize the mechanical properties and wear resistance of stainless steel.

[0028] Niobium (Nb): Nb can dissolve in the iron matrix and improve the strength and hardness of stainless steel through solid solution strengthening. At the same time, Nb can act as a grain boundary strengthening element, promote grain refinement, improve the toughness and tensile properties of the material, and affect the phase transformation behavior of stainless steel, which helps to optimize the microstructure and properties of duplex stainless steel.

[0029] Titanium (Ti): The strengthening effect of Ti is mainly reflected in two aspects: grain refinement and precipitation strengthening. Appropriate Ti addition can act as nucleation sites during the solidification process of the molten pool, promoting microstructure refinement. The abundance of fine grain boundaries effectively hinders dislocation movement, thereby limiting deformation and crack propagation, and improving the yield strength and impact toughness of the steel.

[0030] Al (aluminum) element: In steel, Al combines with other alloying elements to form the main precipitated phases: γ' phase (Ni3Al, (Ni,Co)3(Al,Ti)), β phase (NiAl), and η phase (Ni3(Al,Ti)). Among them, the γ' phase has high strength and toughness, and its strength tends to increase with increasing temperature, while maintaining a certain degree of plasticity, making it an ideal choice for strengthening stainless steel. The β phase has relatively high hardness but is a hard and brittle phase. In Fe-based alloys, nickel (Ni) and aluminum (Al) tend to form the NiAl phase first, rather than the Ni3Al phase. Only with the addition of Ti and Al can the γ'-Ni3(Ti,Al) phase with a significant strengthening effect be generated. The strengthening effect of the η phase depends on the difference in its precipitation morphology at different precipitation temperatures and its orientation relationship with the matrix. However, when the aluminum content in the flux-cored wire is too high, it will significantly affect the wire's process performance, leading to increased spatter and cracking tendency during welding, and adversely affecting the toughness of the deposited metal.

[0031] Mn and Si elements: In the welding process, the main role of Mn and Si is deoxidation and desulfurization, which reduces the oxygen and sulfur content in the weld overlay alloy and prevents defects such as porosity in the weld overlay metal, thus reducing the forming quality.

[0032] CrN: The role of CrN in duplex stainless steel is mainly reflected in enhancing its corrosion resistance and mechanical properties. As a hard, wear-resistant compound, CrN can effectively improve the surface hardness and wear resistance of stainless steel, extending its service life. Furthermore, CrN can improve the corrosion resistance of stainless steel, giving it better corrosion resistance in harsh environments, thus expanding its application range in industrial and manufacturing fields.

[0033] The outer sheath is made of 0Cr18Ni9 austenitic stainless steel strip, and the filling amount of the core powder is controlled at 20wt%-25wt%.

[0034] This invention also provides a 3D printing method for duplex stainless steel structural components, specifically prepared according to the following steps: Step 1: Weigh the following raw materials according to their mass percentages: 22-28% chromium powder, 1-2% titanium powder, 6-8% molybdenum powder, 2-3% copper powder, 5-7% niobium powder, 2-4% aluminum powder, 0.03% carbon powder, 1-2% manganese powder, 0.3-0.6% silicon powder, 0.1-0.2% chromium nitride, and the remainder is iron powder. Step 2: Heat and keep warm the raw material powder weighed in Step 1 in an inert gas atmosphere to remove moisture; In step 2, the heating temperature is 150℃~200℃, and the holding time is 2h~2.5h.

[0035] Step 3: Place the outer sheath on the feeding machine of the welding wire forming machine, and roll the outer sheath into a U-shaped groove through the pressing groove of the forming machine. After keeping the raw material powder obtained in Step 2 warm, cool it to room temperature in the furnace. Then fill the powder into the U-shaped groove. The filling rate of the flux core powder is controlled at 20wt%-25wt%. After passing through the closed forming roller, a 2.10mm welding wire is made. Finally, a 1.20mm metal mold flux core welding wire is made by gradually reducing the diameter. In step 3, the inert atmosphere is argon gas with a purity of 99.999%; in step 3, the outer skin is 0Cr18Ni9 austenitic stainless steel strip.

[0036] Step 4: Assemble the prepared metal-cored welding wire onto the fully automated welding robot, determine the layer height of each layer to be 2-3mm, and write the corresponding program and input it into the welding robot. Use MIG welding as the heat source to 3D print the structural parts.

[0037] In step 4, the process parameters for MIG welding are: welding speed 0.2m / min-0.3m / min; welding torch height 2mm-3mm for each layer; shielding gas 99.999% pure argon; and interpass cooling in step 4, with the interpass temperature controlled between 100℃ and 150℃.

[0038] The duplex stainless steel structural component obtained by 3D printing in this invention is prepared using the method described above.

[0039] Example 1 Step 1: Weigh out the following components by mass percentage: 22% chromium powder, 1% titanium powder, 6% molybdenum powder, 2% copper powder, 5% niobium powder, 2% aluminum powder, 0.03% carbon powder, 1% manganese powder, 0.3% silicon powder, 0.1% chromium nitride, and the remainder is iron powder. The sum of the mass percentages of the above components is 100%. Step 2: Mix all the raw materials weighed in Step 1 evenly and place them in a tube furnace. Keep the furnace at 200°C for 2.5 hours under continuous argon gas supply.

[0040] Step 3: Place a 0Cr18Ni9 austenitic stainless steel strip with a width of 7mm and a thickness of 0.3mm (composition as shown in Table 1) on the feeding machine of the wire forming machine. Roll the steel strip into a U-shaped groove through the pressing groove of the forming machine. Put the flux-cored powder obtained in Step 2 into the U-shaped groove. The filling rate of the flux-cored powder is controlled at 21wt%. Then, use the forming machine to close the U-shaped groove. Wipe it clean with acetone or anhydrous ethanol and draw it into a welding wire with a diameter of 2.1mm. Then reduce the diameter to 1.20mm. Wipe the oil stains on the welding wire with a cotton cloth dipped in acetone or anhydrous ethanol. Finally, straighten the welding wire, coil it into a disc, and seal it in packaging to obtain the duplex stainless steel metal mold flux-cored welding wire for 3D printing.

[0041] Step 4: Load the prepared duplex stainless steel metal mold flux-cored welding wire for 3D printing into the fully automatic welding robot, determine the layer height of each layer to be 2-3mm, write the program and input it into the welding machine, run the welding machine commands, and use MIG welding as the heat source to 3D print the structural parts; the specific parameters of the welding process are: welding speed of 0.2m / min-0.3m / min; lifting of the welding torch by 2mm-3mm for each layer; shielding gas of 99.999% argon.

[0042] The duplex stainless steel parts prepared in this example have a beautiful shape, no obvious spatter, a tensile strength of up to 783.6 MPa, and an elongation of 19.5%.

[0043] Example 2 Step 1: Weigh out the following by mass percentage: 24% chromium powder, 1% titanium powder, 6.5% molybdenum powder, 2.5% copper powder, 5.5% niobium powder, 2.5% aluminum powder, 0.03% carbon powder, 1.5% manganese powder, 0.4% silicon powder, 0.15% chromium nitride, and the remainder is iron powder. Step 2: Mix all the raw materials weighed in Step 1 evenly and place them in a tube furnace. Keep the furnace at 200°C for 2.5 hours under continuous argon gas supply.

[0044] Step 3: Place a 0Cr18Ni9 austenitic stainless steel strip with a width of 7mm and a thickness of 0.3mm (composition as shown in Table 1) on the feeding machine of the wire forming machine. Roll the steel strip into a U-shaped groove through the pressing groove of the forming machine. Put the flux-cored powder obtained in Step 2 into the U-shaped groove. The filling rate of the flux-cored powder is controlled at 24wt%. Then, use the forming machine to close the U-shaped groove. Wipe it clean with acetone or anhydrous ethanol and draw it into a welding wire with a diameter of 2.1mm. Then reduce the diameter to 1.20mm. Wipe the oil stains on the welding wire with a cotton cloth dipped in acetone or anhydrous ethanol. Finally, straighten the welding wire, coil it into a disc, and seal it in packaging to obtain the duplex stainless steel metal mold flux-cored welding wire for 3D printing.

[0045] Step 4: Load the prepared duplex stainless steel metal mold flux-cored welding wire for 3D printing into the fully automatic welding robot, determine the layer height of each layer to be 2-3mm, write the program and input it into the welding machine, run the welding machine commands, and use MIG welding as the heat source to 3D print the structural parts; the specific parameters of the welding process are: welding speed of 0.2m / min-0.3m / min; lifting of the welding torch by 2mm-3mm for each layer; shielding gas of 99.999% argon.

[0046] The duplex stainless steel parts prepared in this example have good mechanical properties, no obvious spatter, a tensile strength of up to 815.2 MPa, and an elongation of 17.6%.

[0047] Example 3 Step 1: Weigh out the following components by mass percentage: 26% chromium powder, 1.5% titanium powder, 7.5% molybdenum powder, 2.5% copper powder, 6% niobium powder, 3% aluminum powder, 0.03% carbon powder, 2% manganese powder, 0.4% silicon powder, 0.2% chromium nitride, and the remainder is iron powder. The sum of the mass percentages of the above components shall be 100%. Step 2: Mix all the raw materials weighed in Step 1 evenly and place them in a tube furnace. Keep the furnace at 200°C for 2.5 hours under continuous argon gas supply.

[0048] Step 3: Place a 0Cr18Ni9 austenitic stainless steel strip with a width of 7mm and a thickness of 0.3mm (composition as shown in Table 1) on the feeding machine of the wire forming machine. Roll the steel strip into a U-shaped groove through the pressing groove of the forming machine. Put the flux-cored powder obtained in Step 2 into the U-shaped groove. The filling rate of the flux-cored powder is controlled at 23wt%. Then, use the forming machine to press and close the U-shaped groove. Wipe it clean with acetone or anhydrous ethanol and draw it into a welding wire with a diameter of 2.1mm. Then reduce the diameter to 1.20mm. Wipe the oil stains on the welding wire with a cotton cloth dipped in acetone or anhydrous ethanol. Finally, straighten the welding wire, coil it into a disc, and seal it in packaging to obtain the duplex stainless steel metal mold flux-cored welding wire for 3D printing.

[0049] Step 4: Load the prepared duplex stainless steel metal mold flux-cored welding wire for 3D printing into the fully automatic welding robot, determine the layer height of each layer to be 2-3mm, write the program and input it into the welding machine, run the welding machine commands, and use MIG welding as the heat source to 3D print the structural parts; the specific parameters of the welding process are: welding speed of 0.2m / min-0.3m / min; lifting of the welding torch by 2mm-3mm for each layer; shielding gas of 99.999% argon.

[0050] The duplex stainless steel part prepared in this example has no surface cracks or pores, no obvious spatter during welding, and a tensile strength of up to 824.2 MPa and an elongation of 20.8%.

[0051] Example 4 Step 1: Weigh out the following components by mass percentage: 28% chromium powder, 2% titanium powder, 8% molybdenum powder, 3% copper powder, 7% niobium powder, 4% aluminum powder, 0.03% carbon powder, 2% manganese powder, 0.6% silicon powder, 0.2% chromium nitride, and the remainder is iron powder. The sum of the mass percentages of the above components is 100%. Step 2: Mix all the raw materials weighed in Step 1 evenly and place them in a tube furnace. Keep the furnace at 200°C for 2.5 hours under continuous argon gas supply.

[0052] Step 3: Place a 0Cr18Ni9 austenitic stainless steel strip with a width of 7mm and a thickness of 0.3mm (composition as shown in Table 1) on the feeding machine of the wire forming machine. Roll the steel strip into a U-shaped groove through the pressing groove of the forming machine. Put the flux-cored powder obtained in Step 2 into the U-shaped groove. The filling rate of the flux-cored powder is controlled at 25wt%. Then, use the forming machine to press and close the U-shaped groove. Wipe it clean with acetone or anhydrous ethanol and draw it into a welding wire with a diameter of 2.1mm. Then reduce the diameter to 1.20mm. Wipe the oil stains on the welding wire with a cotton cloth dipped in acetone or anhydrous ethanol. Finally, straighten the welding wire, coil it into a disc, and seal it in packaging to obtain the duplex stainless steel metal mold flux-cored welding wire for 3D printing.

[0053] Step 4: Load the prepared duplex stainless steel flux-cored welding wire for 3D printing into a fully automated welding robot, ensuring each layer height is 2-3 mm. Input the program into the welding machine, run the welding machine commands, and use MIG welding as the heat source to 3D print the structural component. Specific welding parameters are: welding speed 0.2 m / min-0.3 m / min; torch height 2 mm-3 mm per layer; shielding gas 99.999% argon. Based on the method of duplex stainless steel flux-cored welding and 3D printing of structural components according to this invention, the duplex stainless steel component obtained in this example has a beautiful shape. The macroscopic morphology shows that the assembled part exhibits obvious layering, with good metallurgical bonding between layers and no defects such as porosity or inclusions. Its microstructure is as follows: Figure 2 As shown, the microstructure is austenite (A) + ferrite (δ-F). The lighter-colored areas in the figure represent austenite, and the darker-colored areas represent ferrite. The ratio of austenite to ferrite is close to 1:1, perfectly consistent with the microstructure of duplex stainless steel. Mechanical property testing yielded its stress-strain curve as shown in the figure. Figure 1 As shown, the tensile strength of the molded part in this example reaches 847.8 MPa, and the elongation is 21.5%. In summary, the duplex stainless steel obtained by this invention has good mechanical properties and fully meets the requirements for use in flange structural components.

[0054] Table 1 shows the chemical composition (mass fraction %) of the 0Cr18Ni9 austenitic stainless steel strip used. element C Cr Ni Mn Si S P Fe content 0.06 18.67 8.53 1.51 0.42 0.014 0.032 Bal. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A duplex stainless steel flux-cored welding wire for 3D printed flange structural parts, comprising a flux core and an outer sheath, characterized in that, The core is composed of the following components by mass percentage: 22-28% chromium powder, 1-2% titanium powder, 2-4% aluminum powder, 6-8% molybdenum powder, 2-3% copper powder, 5-7% niobium powder, 0.03% carbon powder, 1-2% manganese powder, 0.3-0.6% silicon powder, 0.1-0.2% chromium nitride, and the remainder is iron powder, with the sum of the mass percentages of the above components being 100%. The 3D printed flange structure is a duplex stainless steel structure with a ferrite to austenite ratio of 1:

1. The outer sheath is made of 0Cr18Ni9 austenitic stainless steel strip, and the core powder filling rate is controlled at 20wt%-25wt%.

2. A 3D printing method for duplex stainless steel structural components, characterized in that, The duplex stainless steel flux-cored welding wire for 3D printed flange structural parts as described in claim 1 is used, specifically according to the following steps: Step 1: Weigh out the following components by mass percentage: 22-28% chromium powder, 1-2% titanium powder, 2-4% aluminum powder, 6-8% molybdenum powder, 2-3% copper powder, 5-7% niobium powder, 0.03% carbon powder, 1-2% manganese powder, 0.3-0.6% silicon powder, 0.1-0.2% chromium nitride, and the remainder is iron powder. The sum of the mass percentages of the above components shall be 100%. Step 2: Heat and keep warm the alloy powder weighed in Step 1 in an inert gas atmosphere to remove moisture; Step 3: After holding the alloy powder obtained in Step 2 at a certain temperature, cool it to room temperature in the furnace. Then fill the powder into the U-shaped groove of the austenitic stainless steel strip, and make it into a welding wire with a diameter of 2.10 mm after passing through the closed forming roll. Finally, make a metal mold flux-cored welding wire with a diameter of 1.20 mm by gradually reducing the diameter. Step 4: Assemble the prepared metal-cored welding wire into the fully automated welding robot, plan the welding path, determine the layer height, and input the program into the welding machine. Run the welding machine commands and use MIG welding as the heat source to 3D print the structural parts.

3. The 3D printing method for duplex stainless steel structural parts according to claim 2, characterized in that, In step 2, the inert atmosphere is 99.999% argon.

4. The 3D printing method for duplex stainless steel structural parts according to claim 2, characterized in that, In step 2, the heating temperature is 150~200℃ and the holding time is 2~2.5h.

5. The 3D printing method for duplex stainless steel structural parts according to claim 2, characterized in that, The process parameters for the MIG welding are as follows: welding speed of 0.2-0.3 m / min; welding torch lifting height of 2-3 mm per layer; and shielding gas of 99.999% argon.

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