Nb-cu based welding wire for welding titanium-steel dissimilar materials and preparation method thereof

Abstract

This invention discloses an Nb-Cu-based welding wire for welding dissimilar materials of titanium and steel, comprising a flux core and a welding sheath. The flux powder is composed of the following components by mass percentage: 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y₂O₃ powder, and the remainder being Nb powder, with the sum of the mass percentages of the above components being 100%. This welding wire solves the cracking problem during the fusion welding of dissimilar materials of titanium and steel. A method for preparing the Nb-Cu-based welding wire for welding dissimilar materials of titanium and steel is also disclosed.

Description

Technical Field

[0001] This invention belongs to the field of metal material welding technology, specifically relating to an Nb-Cu-based welding wire for welding dissimilar materials such as titanium and steel. This invention also relates to a method for preparing the Nb-Cu-based welding wire for welding dissimilar materials such as titanium and steel. Background Technology

[0002] Joining dissimilar materials like titanium and steel has long been a challenging problem in engineering practice. The main reason is that titanium and steel are metallurgically incompatible; direct fusion welding results in the formation of brittle Fe-Ti intermetallic compounds. These compounds are extremely hard, leading to severe joint cracking, and in some cases, the joint even detaches immediately after welding. However, welded titanium-steel dissimilar material structures can effectively combine the excellent corrosion resistance of titanium with the high strength and low cost of steel, thus showing great promise for applications.

[0003] Existing research indicates that an effective way to avoid cracking in titanium-steel dissimilar joints is to prevent the metallurgical reaction between Ti and Fe. However, preventing the reaction of Ti and Fe under fusion welding conditions is extremely difficult. Although high-energy beam welding, such as laser and electron beam welding, has a concentrated heat source and produces smaller weld joints, these two methods are impractical for actual engineering field applications. Highly adaptable arc welding methods, such as MIG and TIG, have become the preferred choice for welding titanium-steel dissimilar materials in practical engineering fields. However, controlling the reaction of Ti and Fe through the welding process under conventional arc welding methods is very difficult; it is necessary to indirectly achieve direct fusion welding of titanium and steel using one or more of these elements. Summary of the Invention

[0004] The purpose of this invention is to provide an Nb-Cu based welding wire for welding dissimilar materials such as titanium and steel, which solves the cracking problem during the fusion welding of dissimilar materials such as titanium and steel.

[0005] Another object of the present invention is to provide a method for preparing Nb-Cu based welding wire for welding dissimilar materials such as titanium and steel.

[0006] The first technical solution adopted in this invention is an Nb-Cu based welding wire for welding dissimilar materials such as titanium and steel, comprising a flux core and a welding sheath, wherein the flux powder is composed of the following components by mass percentage: 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y2O3 powder, and the remainder is Nb powder, the sum of the mass percentages of the above components being 100%.

[0007] The invention is further characterized in that,

[0008] The purity of all six powders is ≥99.9%.

[0009] The particle size of all six powders is 100-200 mesh.

[0010] The welding layer is made of pure niobium strip, with a thickness of 0.3 mm and a width of 7 mm.

[0011] The filling amount of flux-cored welding wire is controlled between 30wt% and 32wt%.

[0012] The second technical solution adopted in this invention is a method for preparing the above-mentioned Nb-Cu-based welding wire for welding dissimilar titanium and steel materials, the specific steps of which are as follows:

[0013] Step 1: Weigh out 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y2O3 powder, and the remainder is Nb powder, according to the following mass percentages: the sum of the mass percentages of the above components is 100%.

[0014] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at a temperature of 250-280℃ for 2-4 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1-2 hours.

[0015] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm; the filling amount of the flux-cored wire is controlled between 30 wt% and 32 wt%.

[0016] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0017] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0018] The invention is further characterized in that,

[0019] The purity of the six powders in step 1 is ≥99.9%, and the particle size of the six powders is 100-200 mesh.

[0020] In step 3, the pure niobium strip has a thickness of 0.3 mm and a width of 7 mm.

[0021] The beneficial effects of this invention are:

[0022] (1) The flux-cored welding wire of the present invention has a relatively small diameter, fewer alloying elements, is simple to prepare, and is convenient for conventional MIG / TIG welding, making it highly applicable to engineering practice.

[0023] (2) The welding wire of this invention is mainly composed of Nb and Cu elements, which indirectly connect Fe and Ti elements. Combined with multiple alloying elements such as Ag, Cr, Zr, and Y2O3, it achieves a high-quality connection between titanium and steel dissimilar joints.

[0024] (3) The welding wire of the present invention contains Cu and Ag elements. When the welding wire is used for welding dissimilar materials such as titanium and steel, the Ti element of the base material together with the Cu and Ag elements form a ternary eutectic phase, which has good plasticity and toughness and effectively prevents the weld from cracking. Attached Figure Description

[0025] Figure 1 The microstructure of the steel side of the flux-cored welding wire prepared in Example 2 during titanium-steel dissimilar material welding;

[0026] Figure 2 The microstructure of the weld seam when the flux-cored welding wire prepared in Example 2 is used for welding dissimilar materials such as titanium and steel;

[0027] Figure 3 The flux-cored welding wire prepared in Example 2 was used for titanium-steel dissimilar material welding, and the tensile fracture morphology of the joint after welding was obtained. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] This invention provides an Nb-Cu based welding wire for welding dissimilar materials such as titanium and steel, comprising a flux core and a welding sheath, wherein the flux powder is composed of the following components by mass percentage: 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y2O3 powder, and the remainder is Nb powder, the sum of the mass percentages of the above components being 100%.

[0030] The purity of all six powders is ≥99.9%; the particle size of all six powders is 100-200 mesh; the welding skin is made of pure niobium strip with a thickness of 0.3 mm and a width of 7 mm; the filling amount of the flux-cored welding wire is controlled between 30 wt% and 32 wt%.

[0031] The roles and functions of each component in this flux-cored welding wire are as follows:

[0032] (1) Nb is the main alloying element of welding wire. According to the Nb-Ti binary phase diagram, Nb and Ti can be infinitely dissolved at high temperature, resulting in excellent weldability. According to the Nb-Fe binary phase diagram, both have a certain degree of solid solubility. Even if the solid solubility is exceeded, the resulting structure is mainly iron-based solid solution with dispersed Fe2Nb hard phase, resulting in good weld toughness and low cracking sensitivity.

[0033] (2) Cu is the main alloying element in welding wire powder. According to the Cu-Fe binary phase diagram, the two do not form brittle intermetallic compounds and can be welded. According to the Cu-Nb binary phase diagram, Nb and Cu do not form intermetallic compounds and can be welded. According to the Cu-Ti binary phase diagram, although Cu and Ti will form various intermetallic compounds, their brittleness is much lower than that of the Fi-Ti brittle phase.

[0034] The aforementioned Cu and Nb elements are the main alloying elements of the flux-cored welding wire of this invention.

[0035] (3) Ag is the main alloying element in welding wire flux. Ag has a low melting point, and according to the binary phase diagrams of Ag-Fe and Ag-Ti, no brittle intermetallic phases are generated during welding. Furthermore, Ag, Cu, and Ti will form a eutectic structure with good plasticity and toughness, thereby avoiding the formation of a large-scale Cu-Ti phase.

[0036] (4) Cr and Zr are additive elements in welding wire flux. Zr has a similar effect to Nb, and can be infinitely dissolved with Ti at high temperatures, thereby further improving the bonding strength between the weld and the titanium base material. Cr has high weldability with steel, and adding a small amount of Cr can improve the bonding strength between the weld and the steel.

[0037] (5) The addition of Y2O3 oxide can purify the grain boundaries of the weld and improve the grain boundary bonding force, thereby improving the ductility and toughness of the Nb-Cu weld. In addition, Y2O3 can also refine the size of Cu-Ti intermetallic compounds.

[0038] This invention also provides a method for preparing the above-mentioned Nb-Cu-based welding wire for welding dissimilar titanium and steel materials, the specific steps of which are as follows:

[0039] Step 1: Weigh out 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y2O3 powder, and the remainder is Nb powder, according to the following mass percentages. The sum of the mass percentages of the above components is 100%. The purity of the six powders in Step 1 is ≥99.9%, and the particle size of the six powders is 100-200 mesh.

[0040] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at a temperature of 250-280℃ for 2-4 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1-2 hours.

[0041] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in Step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. The filling amount of the flux-cored wire is controlled between 30 wt% and 32 wt%. In Step 3, the thickness of the pure niobium strip is 0.3 mm and the width is 7 mm.

[0042] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0043] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0044] Example 1

[0045] Step 1: Weigh out 70% Cu powder, 5% Ag powder, 1% Cr powder, 1% Zr powder, 0.5% Y2O3 powder, and the remainder is Nb powder, according to the following mass percentages. The sum of the mass percentages of the above components is 100%. The purity of the six powders in Step 1 is ≥99.9%, and the particle size of the six powders is 200 mesh.

[0046] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 250℃ for 2 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1 hour.

[0047] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in Step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm; the filling amount of the flux-cored wire is controlled at 32 wt%; in Step 3, the thickness of the pure niobium strip is 0.3 mm and the width is 7 mm.

[0048] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0049] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0050] Titanium-steel dissimilar material welding was performed using the Nb-Cu welding wire prepared in Example 1. MIG welding was performed using a CMT welding power source, with no preheating required. The welding current was 150-180 A, and the shielding gas was pure argon with a flow rate of 15-18 L / min. The results are as follows:

[0051] (1) The titanium-steel dissimilar material joint was well bonded and no crack defects were observed;

[0052] (2) The tensile strength of the titanium-steel dissimilar material joint is 473 MPa, the elongation after fracture is 15%, and the fracture surface is composed of quasi-cleavage + bremsstrahlung morphology.

[0053] (3) The average micro Vickers hardness at the center of the weld of the titanium-steel dissimilar material joint was 340 HV0.2. Example 2

[0054] Step 1: Weigh out 80% Cu powder, 10% Ag powder, 3% Cr powder, 3% Zr powder, 1% Y2O3 powder, and the remainder is Nb powder, according to the following mass percentages. The sum of the mass percentages of the above components is 100%. The purity of the six powders in Step 1 is ≥99.9%, and the particle size of the six powders is 100 mesh.

[0055] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 280℃ for 4 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 2 hours.

[0056] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in Step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm; the filling amount of the flux-cored wire is controlled at 30 wt%; in Step 3, the thickness of the pure niobium strip is 0.3 mm and the width is 7 mm.

[0057] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0058] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0059] Titanium-steel dissimilar material welding was performed using the Nb-Cu welding wire prepared in Example 2. MIG welding was performed using a CMT welding power source, with no preheating required. The welding current was 150-180 A, and the shielding gas was pure argon with a flow rate of 15-18 L / min. The results are as follows:

[0060] (1) The titanium-steel dissimilar material joint was well bonded and no crack defects were observed;

[0061] (2) The tensile strength of the titanium-steel dissimilar material joint is 477 MPa, the elongation after fracture is 14.2%, and the fracture surface is composed of quasi-cleavage + bremsstrahlung morphology.

[0062] (3) The average micro Vickers hardness at the center of the weld of the titanium-steel dissimilar material joint is 345HV0.2.

[0063] Figure 1 The image shows the microstructure of the steel side of the flux-cored welding wire prepared in Example 2 during titanium-steel dissimilar material welding. As can be seen from the image, the weld seam is well bonded to the steel side, and no crack defects are observed.

[0064] Figure 2 The image shows the microstructure of the weld seam when the flux-cored welding wire prepared in Example 2 is used for welding dissimilar materials such as titanium and steel. As can be seen from the image, the weld seam microstructure is mainly composed of Nb-based solid solutions and Cu-based solid solutions, and no crack defects were observed in the weld seam.

[0065] Figure 3 The flux-cored welding wire prepared in Example 2 was used for titanium-steel dissimilar material welding, and the tensile fracture morphology of the weld joint was observed. As can be seen from the figure, bremsstrahlung morphology appears in the fracture surface, and the surface joint has certain plasticity and toughness, which also proves that the developed Nb-Cu-based welding wire effectively dilutes the brittle Fe-Ti phase.

[0066] Example 3

[0067] Step 1: Weigh out 75% Cu powder, 7% Ag powder, 2% Cr powder, 2% Zr powder, 0.7% Y2O3 powder, and the remainder is Nb powder, according to the following mass percentages. The sum of the mass percentages of the above components is 100%. The purity of the six powders in Step 1 is ≥99.9%, and the particle size of the six powders is 200 mesh.

[0068] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 270℃ for 3 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.5 hours.

[0069] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in Step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm; the filling amount of the flux-cored wire is controlled at 31 wt%; in Step 3, the thickness of the pure niobium strip is 0.3 mm and the width is 7 mm.

[0070] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0071] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0072] Titanium-steel dissimilar material welding was performed using the Nb-Cu welding wire prepared in Example 3. MIG welding was performed using a CMT welding power source, with no preheating required. The welding current was 150-180 A, and the shielding gas was pure argon with a flow rate of 15-18 L / min. The results are as follows:

[0073] (1) The titanium-steel dissimilar material joint was well bonded and no crack defects were observed;

[0074] (2) The tensile strength of the titanium-steel dissimilar material joint is 483 MPa, the elongation after fracture is 14.1%, and the fracture surface is composed of quasi-cleavage + bremsstrahlung morphology.

[0075] (3) The average micro Vickers hardness at the center of the weld of the titanium-steel dissimilar material joint is 374HV0.2.

[0076] Example 4

[0077] Step 1: Weigh out the following components by mass percentage: 78% Cu powder, 6% Ag powder, 1.3% Cr powder, 1.3% Zr powder, 0.6% Y2O3 powder, with the remainder being Nb powder. The sum of the mass percentages of these components is 100%. The purity of all six powders in Step 1 is ≥99.9%, and the particle size of all six powders is 200 mesh.

[0078] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 265℃ for 2.4 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.2 hours.

[0079] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in Step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm; the filling amount of the flux-cored wire is controlled at 32 wt%; in Step 3, the thickness of the pure niobium strip is 0.3 mm and the width is 7 mm.

[0080] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0081] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0082] Titanium-steel dissimilar material welding was performed using the Nb-Cu welding wire prepared in Example 4. MIG welding was performed using a CMT welding power source, with no preheating required. The welding current was 150-180 A, and the shielding gas was pure argon with a flow rate of 15-18 L / min. The results are as follows:

[0083] (1) The titanium-steel dissimilar material joint was well bonded and no crack defects were observed;

[0084] (2) The tensile strength of the titanium-steel dissimilar material joint is 449 MPa, the elongation after fracture is 17.2%, and the fracture surface is composed of quasi-cleavage + bremsstrahlung morphology.

[0085] (3) The average micro Vickers hardness at the center of the weld of the titanium-steel dissimilar material joint is 329HV0.2.

[0086] Example 5

[0087] Step 1: Weigh out the following components by mass percentage: 71% Cu powder, 9% Ag powder, 2.7% Cr powder, 2.8% Zr powder, 0.9% Y2O3 powder, with the remainder being Nb powder. The sum of the mass percentages of these components is 100%. The purity of all six powders in Step 1 is ≥99.9%, and the particle size of all six powders is 200 mesh.

[0088] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 265℃ for 3.5 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.1 hours.

[0089] Step 3: Remove the grease from the surface of the pure niobium strip with alcohol, and wrap the flux powder prepared in Step 2 inside the pure niobium strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm; the filling amount of the flux-cored wire is controlled at 32 wt%; in Step 3, the thickness of the pure niobium strip is 0.3 mm and the width is 7 mm.

[0090] Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm.

[0091] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0092] Titanium-steel dissimilar material welding was performed using the Nb-Cu welding wire prepared in Example 5. MIG welding was performed using a CMT welding power source, with no preheating required. The welding current was 150-180 A, and the shielding gas was pure argon with a flow rate of 15-18 L / min. The results are as follows:

[0093] (1) The titanium-steel dissimilar material joint was well bonded and no crack defects were observed;

[0094] (2) The tensile strength of the titanium-steel dissimilar material joint is 458 MPa, the elongation after fracture is 15.7%, and the fracture surface is composed of quasi-cleavage + bremsstrahlung morphology.

[0095] (3) The average micro Vickers hardness at the center of the weld of the titanium-steel dissimilar material joint is 353HV0.2.

Claims

1. A Nb-Cu based welding wire for welding dissimilar materials such as titanium and steel, characterized in that, It includes a flux core and a welding sheath. The flux powder is composed of the following components by mass percentage: 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y2O3 powder, and the remainder is Nb powder. The sum of the mass percentages of the above components is 100%. The welding sheath is made of pure niobium strip. The filling amount of the flux-cored welding wire is controlled at 30wt%-32wt%.

2. The Nb-Cu based welding wire for welding dissimilar materials of titanium and steel according to claim 1, characterized in that, The purity of all six powders is ≥99.9%.

3. The Nb-Cu based welding wire for welding dissimilar materials of titanium and steel according to claim 1, characterized in that, The particle size of all six powders is 100-200 mesh.

4. The Nb-Cu based welding wire for welding dissimilar materials of titanium and steel according to claim 1, characterized in that, The weld bead thickness is 0.3mm and the width is 7mm.

5. The method for preparing Nb-Cu-based welding wire for titanium-steel dissimilar material welding according to claim 1, characterized in that, The specific steps are as follows: Step 1: Weigh out the following components by mass percentage: 70-80% Cu powder, 5-10% Ag powder, 1-3% Cr powder, 1-3% Zr powder, 0.5-1% Y2O3 powder, with the remainder being Nb powder. The sum of the mass percentages of the above components should be 100%. Step 2: Place the powdered core material weighed in Step 1 into a vacuum heating furnace and heat it at a temperature of 250~280℃ for 2~4 hours; place the dried powder into a powder mixer for thorough mixing for 1~2 hours. Step 3: The flux-cored wire powder prepared in Step 2 is wrapped inside a pure niobium strip using a flux-cored wire drawing machine. The diameter of the first drawing die is 2.6 mm. The filling amount of the flux-cored wire is controlled between 30 wt% and 32 wt%. Step 4: After the first drawing process is completed, the die hole diameter is changed to 2.5mm, 2.3mm, 2.1mm, 1.9mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm and 1.2mm respectively for drawing. The final diameter of the flux-cored wire is 1.2mm. Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

6. The method for preparing Nb-Cu-based welding wire for titanium-steel dissimilar material welding according to claim 5, characterized in that, The purity of the six powders in step 1 is ≥99.9%, and the particle size of the six powders is 100~200 mesh.

7. The method for preparing Nb-Cu-based welding wire for titanium-steel dissimilar material welding according to claim 5, characterized in that, In step 3, the pure niobium strip has a thickness of 0.3 mm and a width of 7 mm.

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