A method for reducing amorphous alloy laser cladding cracks by using an inclined double-layer substrate

Abstract

The application discloses a method for reducing amorphous alloy laser cladding cracks by using inclined double-layer substrates. The method adopts double-layer parallel plates without cutting faults as substrates, and performs laser cladding on the substrates in an inclined manner, so as to reduce cracks generated in the process of amorphous alloy laser cladding. The inclination angle θ of the double-layer parallel plates is 5°-30°. The method enhances the liquidity of a molten pool in the printing process and releases thermal stress by deforming a printed part, so as to inhibit crack generation. The substrates are subjected to cutting treatment and are divided into double-layer parallel plates with two layers of different thicknesses without faults, thermal stress in the printing process is released by deforming the thin plate. By adjusting the inclined placement and printing mode of the double-layer parallel plates, the liquidity of a laser molten pool in the printing process is enhanced by means of gravity, and preheating is adopted to reduce the temperature gradient in the printing process, so as to reduce thermal stress and inhibit crack generation.

Description

Technical Field

[0001] This invention relates to a method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate, specifically belonging to the field of laser cladding technology. Background Technology

[0002] Amorphous alloys, also known as amorphous metals or amorphous alloys, are a class of metallic materials with an irregular atomic structure. When a molten liquid alloy is cooled and solidified at an extremely rapid rate, the atoms in the alloy do not have time to arrange themselves in an orderly manner and crystallize, resulting in a solid alloy that exhibits long-range order and short-range disorder. Amorphous alloys differ structurally from crystalline metals. Crystalline metals have ordered atomic arrangements and a well-defined crystal lattice structure. In contrast, the atomic arrangements of amorphous alloys are irregular, exhibiting a highly close-packed amorphous structure.

[0003] Compared to traditional crystalline metals, the disordered nature of amorphous alloys results in superior mechanical properties and unique physical and chemical characteristics, such as high strength, high hardness, excellent toughness, and superior damping performance, giving them broad application potential in multiple fields. Furthermore, amorphous alloys possess a large number of low-coordination surface atoms and defect sites, making them promising candidates for applications in catalysis. Studying the preparation, structure, and property relationships of amorphous alloys can provide important guidance for materials design and processing, making it a crucial research topic in materials science.

[0004] The most common method for preparing amorphous alloys is copper mold suction casting, which has a high cooling rate and yields high amorphous purity. However, this method limits the shape of the mold, making it difficult to fabricate large-sized amorphous components with complex structures. Therefore, researchers have turned their attention to 3D printing technology. 3D printing (3DP), a type of rapid prototyping technology also known as additive manufacturing, does not require molds. It is a technology that uses digital model files as a basis and employs powdered metals or plastics and other bondable materials to construct objects layer by layer. It can produce parts with more diverse shapes and larger sizes than traditional manufacturing methods. Currently, selective laser melting (SLM), selective laser sintering (SLS), laser melting deposition (LMD), and electron beam melting (EBM) are the most commonly used 3D printing technologies.

[0005] Laser cladding processes are mainly classified into several types, including pre-fed powder cladding, synchronous powder cladding, and wire-fed laser cladding, with synchronous powder cladding being the most widely used. In synchronous powder cladding, the cladding powder is fed from the powder feeding pipe by a carrier gas and arrives at the substrate surface simultaneously with the laser beam. After interacting with the laser, the powder enters the molten pool, forming a cladding layer as the laser beam and powder feeding nozzle move synchronously. Due to the small laser spot diameter and high scanning speed, the molten pool size is small, creating a very high cooling rate (10³~10⁸ K / s) for powder melting and solidification, which is significantly higher than the critical cooling rate required for forming amorphous alloys.

[0006] However, laser 3D printing technology has a complex thermal history during the printing process. Amorphous components are prone to recrystallization, reducing the amorphous content in the component. On the other hand, the high energy density of the laser input creates significant thermal stress. Under this stress, atomic rearrangement occurs within the amorphous material, forming shear transition zones that expand into shear bands. Energy is concentrated within these shear bands, which are only tens of nanometers in size, resulting in thermo-mechanical coupling and shear softening, forming voids that then propagate into cracks. Summary of the Invention

[0007] This invention proposes a method for laser cladding of iron-based amorphous alloys onto tilted double-layer substrates, aiming to overcome the aforementioned problems in traditional technologies. This invention suppresses crack formation by enhancing the fluidity of the molten pool and releasing thermal stress through deformation of the printed part during the printing process.

[0008] The present invention provides a method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate. The method uses an uncut double-layer parallel plate as the substrate and performs laser cladding on the substrate in a tilted manner to reduce cracks generated during laser cladding of amorphous alloys. The specific process is as follows: The substrate material is cut into unbroken double-layer parallel plates as the substrate for laser cladding. The substrate is placed at an angle and clamped in the laser cladding printing equipment. Then, iron-based amorphous alloy powder is poured into the powder feeder. The substrate is preheated with a laser and then laser cladding is performed. The printed workpiece after cladding is naturally cooled to room temperature to obtain iron-based amorphous alloy with fewer cracks. The tilt angle of the double-layer parallel plates is 5°~30°.

[0009] The aforementioned unbroken double-layer parallel plate is obtained by wire cutting a No. 45 steel plate to obtain a double-layer parallel plate with two layers of thin and thick that are not completely broken. The thickness of the thin layer is 1~2mm, the thickness of the thick layer is 2.5~3.5mm, and the gap between the two layers is 0.5mm.

[0010] The atomic composition of the iron-based amorphous alloy powder is Fe. 41 Co7Cr 15 Mo14 C 15 B6Y2, with a particle size of 300~400 mesh.

[0011] The preheating process parameters are as follows: spot diameter 2.0 mm, laser power 400~900 W, laser scanning speed 12.0~20 mm / s, laser scanning gap 2 mm, and defocusing amount controlled within 10 ± 2.0 mm.

[0012] The laser cladding process parameters are as follows: spot diameter 2.0 mm, laser power 700~2000 W, laser scanning speed 12.0~30 mm / s, defocusing amount controlled within ±2.0 mm, argon purity 99.9%, and gas flow rate 12~20 L / min.

[0013] The beneficial effects of this invention are as follows: This invention suppresses crack formation by enhancing the fluidity of the molten pool and releasing thermal stress through the deformation of the printed part during the printing process. By cutting the substrate into two parallel double-layer plates of different thicknesses without any breaks, the thermal stress during the printing process is released through the deformation of the thinner plate. Furthermore, by tilting the parallel double-layer plates and adjusting the printing method, gravity is used to enhance the fluidity of the laser molten pool during printing, and preheating is employed to reduce the temperature gradient during printing, thereby reducing thermal stress and suppressing crack formation. Attached Figure Description

[0014] Figure 1 : A schematic diagram of the process for laser cladding of iron-based amorphous alloys onto tilted double-layer substrates according to the present invention; Among them: 1. Laser cladding nozzle; 2. Coaxial powder feeding; 3. Double-layer parallel plate; θ, tilt angle of the double-layer parallel plate; 3-1. Thin-layer substrate; 3-2. Thick-layer substrate; Figure 2 In Embodiment 1 of this invention, a parallel single-layer substrate is used as the defect map for dye penetrant testing of laser cladding parts; Figure 3 Example 2 of this invention: Dye penetrant testing defect map of laser cladding component; Figure 4 Example 3 of this invention: Dye penetrant testing defect map of the cladding component; Figure 5 Example 4 of this invention: Dye penetrant testing defect map of the cladding part. Detailed Implementation

[0015] Example 1 The substrate material is made of No. 45 steel, and the substrate is wire-cut to a size of 20mm*30mm*5mm. Mechanical grinding is used to remove surface oxides, oil stains, etc.

[0016] Iron-based amorphous alloy powder was selected as the cladding powder. Its chemical composition (mass fraction) was 41 wt.% Fe, 7 wt.% Co, 15 wt.% Cr, 14 wt.% Mo, 15 wt.% C, 6 wt.% B, and 2 wt.% Y. The powder was screened with a particle size of 300~400 mesh and dried in a drying oven at 70℃ for 2 hours.

[0017] The substrate is placed in parallel and clamped in a laser cladding printing device. Iron-based amorphous alloy powder is then poured into a powder feeder. After preheating the substrate with a laser, laser cladding is performed. The clad printed workpiece is then allowed to cool naturally to room temperature, resulting in an iron-based amorphous alloy with fewer cracks. The substrate is then clamped in the laser cladding device.

[0018] The preheating process parameters are: spot diameter 2.0mm, laser power 900w, laser scanning speed 12.0mm / s, scanning gap 2mm, and defocusing amount 10mm.

[0019] After preheating, the laser cladding process parameters include: spot diameter 2.0 mm, laser power 700 W, laser scanning speed 12.0 mm / s, defocusing amount 0 mm, and the laser cladding process is protected by argon gas with a purity of 99.9% and a gas flow rate of 12 L / min.

[0020] The crack density of the clad part is 19.68%.

[0021] Example 2 The substrate material is 45 steel, wire-cut into 20mm*30mm*5mm substrates, and then horizontally wire-cut into thin layers with a thickness of 1.0mm and thick layers with a thickness of 3.5mm. The gap between the two parallel layers is 0.5mm. Mechanical grinding is used to remove surface oxides, oil stains, etc.

[0022] Iron-based amorphous alloy powder was selected as the cladding powder. Its chemical composition (mass fraction) was 41 wt.% Fe, 7 wt.% Co, 15 wt.% Cr, 14 wt.% Mo, 15 wt.% C, 6 wt.% B, and 2 wt.% Y. The powder was screened with a particle size of 300~400 mesh and dried in a drying oven at 70℃ for 2 hours.

[0023] The substrate material is cut into unbroken double-layer parallel plates to serve as the substrate for laser cladding. The substrate is placed at an angle (θ) and clamped in the laser cladding printing equipment. Iron-based amorphous alloy powder is then poured into the powder feeder. After preheating the substrate with a laser, laser cladding is performed. The clad printed workpiece is then allowed to cool naturally to room temperature, resulting in an iron-based amorphous alloy with few cracks. The workpiece is then clamped in the laser cladding equipment.

[0024] The preheating process parameters are: spot diameter 2.0mm, laser power 900w, laser scanning speed 12.0mm / s, scanning gap 2mm, and defocusing amount 10mm.

[0025] After preheating, the laser cladding process parameters include: spot diameter 2.0 mm, laser power 700 W, laser scanning speed 12.0 mm / s, defocusing amount 0 mm, and the laser cladding process is protected by argon gas with a purity of 99.9% and a gas flow rate of 12 L / min.

[0026] The crack density of the cladding component is 13.00%.

[0027] Example 3 The substrate material is 45 steel, wire-cut into 20mm*30mm*5mm substrates, and then horizontally wire-cut into thin layers with a thickness of 1.5mm and thick layers with a thickness of 3.0mm. The gap between the two parallel layers is 0.5mm. Mechanical grinding is used to remove surface oxides, oil stains, etc.

[0028] Iron-based amorphous alloy powder was selected as the cladding powder. Its chemical composition (mass fraction) was 41 wt.% Fe, 7 wt.% Co, 15 wt.% Cr, 14 wt.% Mo, 15 wt.% C, 6 wt.% B, and 2 wt.% Y. The powder was screened with a particle size of 300~400 mesh and dried in a drying oven at 70℃ for 2 hours.

[0029] The substrate material is cut into unbroken double-layer parallel plates to serve as the substrate for laser cladding. The substrate is placed at an angle (θ) and clamped in the laser cladding printing equipment. Iron-based amorphous alloy powder is then poured into the powder feeder. After preheating the substrate with a laser, laser cladding is performed. The clad printed workpiece is then allowed to cool naturally to room temperature, resulting in an iron-based amorphous alloy with few cracks. The workpiece is then clamped in the laser cladding equipment.

[0030] The laser preheating process parameters are: spot diameter 2.0mm, laser power 600w, laser scanning speed 12.0mm / s, scanning gap 2mm, and defocusing amount 10mm.

[0031] After preheating, the laser cladding process parameters include: spot diameter 2.0 mm, laser power 700 W, laser scanning speed 12.0 mm / s, defocusing amount 0 mm, and the laser cladding process is protected by argon gas with a purity of 99.9% and a gas flow rate of 12 L / min.

[0032] The crack density of the clad part is 8.36%.

[0033] Example 4 The substrate material is 45 steel, wire-cut into 20mm*30mm*5mm substrates, and then horizontally wire-cut into thin layers with a thickness of 2.0mm and thick layers with a thickness of 2.5mm. The gap between the two parallel layers is 0.5mm. Mechanical grinding is used to remove surface oxides, oil stains, etc.

[0034] Iron-based amorphous alloy powder was selected as the cladding powder. Its chemical composition (mass fraction) was 41 wt.% Fe, 7 wt.% Co, 15 wt.% Cr, 14 wt.% Mo, 15 wt.% C, 6 wt.% B, and 2 wt.% Y. The powder was screened with a particle size of 300~400 mesh and dried in a drying oven at 70℃ for 2 hours.

[0035] The substrate material is cut into unbroken double-layer parallel plates to serve as the substrate for laser cladding. The substrate is placed at an angle (θ) and clamped in the laser cladding printing equipment. Iron-based amorphous alloy powder is then poured into the powder feeder. After preheating the substrate with a laser, laser cladding is performed. The clad printed workpiece is then allowed to cool naturally to room temperature, resulting in an iron-based amorphous alloy with few cracks. The workpiece is then clamped in the laser cladding equipment.

[0036] The laser preheating process parameters are: spot diameter 2.0mm, laser power 400w, laser scanning speed 12.0mm / s, scanning gap 2mm, and defocusing amount 10mm.

[0037] After preheating, the laser cladding process parameters include: spot diameter 2.0 mm, laser power 700 W, laser scanning speed 12.0 mm / s, defocusing amount 0 mm, and the laser cladding process is protected by argon gas with a purity of 99.9% and a gas flow rate of 12 L / min.

[0038] The crack density of the clad part is 6.95%.

Claims

1. A method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate, characterized in that: The method uses an uncut double-layer parallel plate as a substrate and performs laser cladding on the substrate in an inclined manner to reduce cracks generated by laser cladding of amorphous alloys. The specific process is as follows: The substrate material is transversely cut into thin and thick double-layer parallel plates without breaks along a direction parallel to the substrate surface. These plates are used as the substrate for laser cladding. The substrate is placed at an angle and clamped in the laser cladding printing equipment. Then, iron-based amorphous alloy powder is poured into the powder feeder. After the substrate is preheated with a laser, laser cladding is performed on the thin surface of the thin double-layer parallel plate. The clad printed workpiece is naturally cooled to room temperature to obtain an iron-based amorphous alloy with few cracks. The tilt angle θ of the double-layer parallel plate is 5°~30°.

2. The method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate according to claim 1, characterized in that: The aforementioned unbroken double-layer parallel plate is obtained by wire cutting a No. 45 steel plate to obtain a double-layer parallel plate with two layers of thin and thick that are not completely broken. The thickness of the thin layer is 1~2mm, the thickness of the thick layer is 2.5~3.5mm, and the gap between the two layers is 0.5mm.

3. The method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate according to claim 1, characterized in that: The atomic composition of the iron-based amorphous alloy powder is Fe. 41 Co7Cr 15 Mo 14 C 15 B6Y2, with a particle size of 300~400 mesh.

4. The method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate according to claim 1, characterized in that: The preheating process parameters are as follows: spot diameter 2.0 mm, laser power 400~900 W, laser scanning speed 12.0~20 mm / s, laser scanning gap 2 mm, and defocusing amount controlled within 10 ± 2.0 mm.

5. The method for reducing laser cladding cracks in amorphous alloys using a tilted double-layer substrate according to claim 1, characterized in that: The laser cladding process parameters are as follows: spot diameter 2.0 mm, laser power 700~2000 W, laser scanning speed 12.0~30 mm / s, defocusing amount controlled within ±2.0 mm, argon purity 99.9%, and gas flow rate 12~20 L / min.

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