Laser additive manufacturing method with low heat input and high deposition efficiency and application

Abstract

The invention discloses a laser additive manufacturing method with low heat input and high deposition efficiency and application. The invention belongs to the field of additive manufacturing. The invention aims to solve the technical problem that the existing laser additive manufacturing method cannot meet the deposition quality of a workpiece and also cannot consider the deposition efficiency under the condition of low heat input. According to the method, a metal welding strip is used as a filling material, rectangular laser is used as a heat source, and layer-by-layer deposition is carried out under Ar gas protection. The characteristics that the middle section of a rectangular laser spot is flat and the edge is steep are coupled with the strip-shaped filling metal, the uniformity of energy distribution of the rectangular laser on the strip-shaped metal is further improved, it is guaranteed that good interlayer metallurgical bonding of the filling metal material is achieved under the limited heat input condition, and the deposition speed can be increased to the maximum extent. In addition, under the combined action of the rectangular laser and the rectangular welding strip, the high deposition rate is met, and meanwhile the high deposition yield can be obtained. The method can be applied to additive manufacturing of other heat-sensitive alloys.

Description

Technical Field

[0001] The present invention belongs to the field of additive manufacturing, and specifically relates to a laser additive manufacturing method and application with low heat input and high deposition efficiency. Background Art

[0002] Additive Manufacturing (AM), also known as 3D printing, is a technology that constructs objects by printing layer by layer based on digital model files. Additive manufacturing uses software to slice the three-dimensional model of an object, and then uses specific equipment to stack the materials layer by layer according to the slice information to eventually form a complete solid object. This technology has the advantages of high design freedom, fast molding speed, material saving and personalized customization, and is widely used in many key manufacturing fields.

[0003] As a key technical parameter in additive manufacturing technology, heat input can significantly affect the uniformity of the structure, grain size and residual stress of metal parts, and also affect the dimensional accuracy and surface quality of the parts. Lower heat input can reduce the interlayer remelting zone and avoid the formation of coarse grains, thereby improving the mechanical properties of the material such as strength, hardness and toughness. Low heat input can also effectively reduce the molten pool fluctuation, improve the dimensional accuracy and stability of the parts, reduce local stress concentration and improve the overall reliability of the parts. For some heat-sensitive materials (such as titanium alloys and magnesium alloys), lower heat input is particularly required in the additive manufacturing process to avoid directional growth of the organization or performance deterioration. Deposition rate (DR), as an important consideration in the additive manufacturing process, is often used to characterize the volume of metal deposited per unit time and is one of the important parameters that additive manufacturing technology urgently needs to improve. The reason why deposition rate is valued is mainly because the improvement of this indicator can greatly shorten the production cycle, improve production capacity and reduce costs. In addition, it can also expand the application scope of additive manufacturing technology in large components in the engineering field.

[0004] Researchers have proposed a variety of methods to reduce heat input in the additive manufacturing process, such as reducing the intensity and size of the heat source, increasing the scanning speed, optimizing the forming strategy, and performing pre-treatment and post-processing. Although these methods can reduce heat input to a certain extent, it is obvious that these methods will reduce the deposition efficiency in the additive manufacturing process to varying degrees and increase the manufacturing cycle of the parts. Therefore, how to meet the deposition quality of the parts under low heat input conditions while taking into account the deposition efficiency is a difficult problem that needs to be overcome in this field. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problem that the existing laser additive manufacturing method cannot meet the deposition quality of the workpiece under low heat input conditions while taking into account the deposition efficiency, and to provide a laser additive manufacturing method and application with both low heat input and high deposition efficiency.

[0006] One of the objects of the present invention is to provide a laser additive manufacturing method with low heat input and high deposition efficiency, the method being carried out in the following steps:

[0007] A metal welding ribbon is used as the filling material and a rectangular laser is used as the heat source. The width of the rectangular laser is greater than the width of the welding ribbon. The angle between the laser beam and the normal line of the substrate surface is set to 2°-6°. The angle between the welding ribbon feeding angle and the normal line of the substrate surface is set to 60°-70°. The welding ribbon moves along the laser scanning direction and is deposited layer by layer under the protection of Ar gas.

[0008] It is further defined that the metal welding strip has a width of 12-30 mm and a thickness of 1-2 mm.

[0009] It is further defined that the difference between the width of the rectangular laser and the width of the metal welding strip is between 2-3 mm, and the length of the rectangular laser is 2-4 mm. The side of the rectangular laser parallel to the laser scanning direction is the length direction of the rectangular laser, and the side of the rectangular laser parallel to the laser scanning direction is the width direction of the rectangular laser.

[0010] It is further defined that the vertical distance between the end of the laser head and the welding strip is 12-16 mm.

[0011] It is further defined that the rectangular laser power is 3200-4800W, the scanning speed is 4-10mm / s, and the metal welding strip feeding speed is 4-15mm / s.

[0012] It is further defined that the dwell time after the laser is started is 200-400ms, and the welding strip feeding mechanism is started after the molten pool is stabilized.

[0013] It is further defined that the inter-layer cooling time is 20-40s.

[0014] A second object of the present invention is to provide an application of the above method in additive manufacturing of heat-sensitive alloys.

[0015] Further defined, heat-sensitive alloys include carbon steel, stainless steel, titanium alloys, magnesium alloys, aluminum alloys, and nickel-based alloys.

[0016] A third object of the present invention is to provide a heat-sensitive alloy obtained by the above application.

[0017] The advantages of the present invention compared to the prior art are:

[0018] The present invention uses a rectangular laser with a flat middle section and steep edges, and couples the flat middle section and steep edges with the strip-shaped filler metal, further improving the uniformity of the energy distribution of the rectangular laser on the strip metal, improving the problem of excessive melting of the wire material by Gaussian energy distribution in laser fuse and arc fuse additive manufacturing technology, greatly improving the energy utilization rate of the heat source, and ensuring that the filler metal material achieves good interlayer metallurgical bonding under limited heat input conditions, and maximizing the deposition rate, thereby achieving the effect of increasing the deposition rate. In addition, under the joint action of the rectangular laser and the rectangular welding strip, a high deposition rate can be achieved while a higher deposition yield can be obtained. It can be applied to additive manufacturing of other heat-sensitive alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the morphology of a single-layer deposited layer in Example 1 of the present invention;

[0020] Figure 2 The surface roughness of the multi-layer 5052 aluminum alloy part in Example 1 of the present invention;

[0021] Figure 3 The surface roughness of the multi-pass 5052 aluminum alloy product in comparative example 1 of the present invention;

[0022] Figure 4 This is a schematic diagram of the yield of multi-layer 5052 aluminum alloy deposition in Example 1 of the present invention;

[0023] Figure 5 This is a schematic diagram of the yield of multi-pass 5052 aluminum alloy deposition in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0026] The terms "comprising," "including," "having," "containing," or any other variations thereof, as used in the following examples, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus comprising the listed elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0027] Embodiment 1: The method for laser additive manufacturing of 5052 aluminum alloy with low heat input and high deposition efficiency in this embodiment is carried out in the following steps:

[0028] (1) Select a 5052 aluminum alloy welding strip with a width of 12 mm and a thickness of 1 mm, select a 5052 aluminum alloy plate with a size of 100 mm × 300 mm × 20 mm as a substrate, treat the substrate to remove the surface oxide layer, and fix the substrate;

[0029] (2) A 14 mm × 2 mm rectangular laser was used as the heat source to ensure that the rectangular laser could completely cover the size of the solder strip. The angle between the laser beam and the normal line of the substrate surface was set to 2°, the angle between the solder strip feeding angle and the normal line of the substrate surface was set to 70°, and the protective gas was Ar.

[0030] (3) The laser power is 4000W, the vertical distance between the laser head and the welding strip is 16mm, the metal welding strip feeding speed is 6mm / s, the laser scanning speed (operating speed) during the additive process is 4mm / s, and the control system is set to stay for 400ms after the laser is started. After the molten pool is stable, the welding strip feeding mechanism is started and moves along the scanning direction. The welding strip is melted under the action of the rectangular laser to form a molten pool, and the deposition of a single layer is completed after solidification;

[0031] (4) During the deposition process, the interlayer cooling time of each deposited layer is 40 s, completing the additive manufacturing of 5052 aluminum alloy.

[0032] Comparative Example 1: The laser fuse additive manufacturing method is carried out according to the following steps:

[0033] (1) Select a 5052 aluminum alloy welding wire with a welding wire diameter of 1.2 mm, select a 5052 aluminum alloy plate with a size of 200 mm × 30 mm × 5 mm as a substrate, treat the substrate to remove the surface oxide layer, and fix the substrate;

[0034] (2) A laser beam with a spot diameter of 0.26 mm was used as the heat source and the protective gas was Ar;

[0035] (3) The laser power is 2800 W, the scanning speed is 0.02 m / s, and the wire feeding speed is 0.04 m / s. The welding wire melts under the action of the laser to form a molten pool, and the single-layer deposition is completed after solidification;

[0036] (4) Adjacent deposited layers are overlapped at a rate of 20% to form a block, completing the additive manufacturing of the aluminum alloy.

[0037] The 5052 aluminum alloy parts manufactured by the additive manufacturing method of the present invention are well formed, have uniform size distribution, and the edges of the deposited layer on both sides are smoothly connected to the substrate. The specific morphology of the single-layer deposited layer is as follows: Figure 1As shown in Table 1, compared with the aluminum alloy laser additive manufacturing in Comparative Example 1, the energy density is reduced by 89.7%. Under the condition of greatly reducing the heat input, the deposition efficiency is 59.3% higher than that in Comparative Example 1. The dimensional accuracy of multilayer deposition is also significantly improved. Figure 2 The schematic diagram of the deposition yield of the multilayer product of the present invention is shown in Figure 3 The calculation formula of deposition yield is as follows:

[0038]

[0039] Where η is the deposition yield, D1 is the effective deposition area, and D2 is the area to be removed. The details are shown in Table 1.

[0040] Table 1 Comparison of deposition effects between laser fuse additive manufacturing and the present invention

[0041]

[0042] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A laser additive manufacturing method with low heat input and high deposition efficiency, characterized in that: The method: A metal welding ribbon is used as the filling material and a rectangular laser is used as the heat source. The width of the rectangular laser is greater than the width of the welding ribbon. The angle between the laser beam and the normal line of the substrate surface is set to 2°-6°. The angle between the welding ribbon feeding angle and the normal line of the substrate surface is set to 60°-70°. The welding ribbon moves along the laser scanning direction and is deposited layer by layer under the protection of Ar gas.

2. The method according to claim 1, characterized in that The metal welding strip width is 12-30mm and the thickness is 1-2mm.

3. The method according to claim 1, characterized in that The difference between the width of the rectangular laser and the width of the metal welding strip is between 2-3 mm, and the length of the rectangular laser is 2-4 mm.

4. The method according to claim 1, characterized in that: The vertical distance between the end of the laser head and the welding strip is 12-16mm.

5. The method according to claim 1, characterized in that The rectangular laser power is 3200-4800W, the scanning speed is 4-10mm / s, and the metal welding strip feeding speed is 4-15mm / s.

6. The method according to claim 1, characterized in that The laser stays for 200-400ms after starting, and the welding strip feeding mechanism is started after the molten pool is stable.

7. The method according to claim 1, characterized in that The inter-layer cooling time is 20-40s.

8. Use of the method according to any one of claims 1 to 7 in additive manufacturing of heat-sensitive alloys.

9. The use according to claim 8, characterized in that: Heat-sensitive alloys include carbon steel, stainless steel, titanium alloys, magnesium alloys, aluminum alloys, and nickel-based alloys.

10. The heat-sensitive alloy obtained by the use according to claim 8 or 9.

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