A method for evaluating the crack resistance of laser cladding additive manufacturing materials

Abstract

This invention discloses a method for evaluating the crack resistance of laser cladding additive manufacturing materials, comprising the following steps: S1: performing laser cladding on the surface of a metal sample to obtain a test cladding layer, and measuring and calculating the cladding width; S2: performing single-layer or multi-layer laser cladding additive manufacturing within an annular groove to obtain a cladding layer for the metal material; S3: calculating the final crack rate of the metal material; S4: repeating steps S1-S3 under the same test conditions for multiple laser cladding additive manufacturing materials to be evaluated, and ranking the final crack rates of the multiple laser cladding additive manufacturing materials. This invention targets the crack resistance of materials during laser cladding additive manufacturing. By performing single-layer or multi-layer laser cladding within the space of an annular groove, the sidewalls of the annular groove exert tensile stress on the solidified cladding layer, causing cracking, thereby evaluating the crack resistance of the material. This method is highly targeted and provides reliable evaluation results.

Description

Technical Field

[0001] This invention relates to a method for evaluating crack resistance, and more particularly to a method for evaluating the crack resistance of laser cladding additive manufacturing materials. Background Technology

[0002] Laser cladding additive manufacturing is a highly efficient additive manufacturing method that uses the high energy of a laser beam to rapidly melt and solidify materials, forming a tightly bonded cladding layer. This layer-by-layer additive manufacturing process creates a complete component. However, due to the rapid heating and cooling characteristics of laser cladding, cracks are easily generated, affecting the quality and service life of the clad additive components. Furthermore, laser cladding additive manufacturing differs fundamentally from traditional laser cladding surface modification, exhibiting significant differences in melt pool composition, solidification path and temperature, and stress distribution, directly impacting crack initiation mechanisms and crack resistance evaluation methods. Existing methods for evaluating the crack resistance of laser cladding are mostly designed for laser cladding surface modification. Directly applying these surface modification evaluation methods to evaluate laser cladding additive manufacturing materials results in low reliability of the evaluation results. Summary of the Invention

[0003] Purpose of the invention: The first purpose of this invention is to provide an evaluation method for the crack resistance of laser cladding additive manufacturing materials with high reliability of evaluation results.

[0004] Technical solution: This invention discloses a method for evaluating the crack resistance of laser cladding additive manufacturing materials, comprising the following steps:

[0005] S1: Select a metal sample made of a laser cladding additive manufacturing material to be evaluated, perform laser cladding on the surface of the metal sample to obtain a test cladding layer, measure and calculate the width of the test cladding layer, and take the width of the test cladding layer as the cladding width of the metal material;

[0006] S2: Construct a crack resistance evaluation device with an annular groove. The material of the crack resistance evaluation device is the same as that of the metal sample in step S1. The width of the annular groove is the same as the cladding width. Use the same cladding powder as in step S1. Perform single-layer or multi-layer laser cladding additive manufacturing along the annular trajectory in the annular groove to obtain the metal material as the cladding layer of the laser cladding additive manufacturing material.

[0007] S3: Take cross-sections of the cladding layer every θ° from the starting position of laser cladding, measure the total crack length and height of each cross-section, calculate the individual crack rate of each cross-section, and calculate the average of all individual crack rates as the final crack rate of the metal material.

[0008] S4: For the various laser cladding additive manufacturing materials to be evaluated, repeat steps S1-S3 under the same test conditions to obtain the final crack rate of the various laser cladding additive manufacturing materials, and rank the final crack rates of the various laser cladding additive manufacturing materials.

[0009] Furthermore, the method for obtaining the cladding width in step S1 is as follows: select multiple locations of the test cladding layer, measure the width of each location, calculate the average width of all sampling points, and use it as the cladding width.

[0010] Furthermore, the formula for calculating the individual crack rate in step S3 is as follows:

[0011]

[0012] Furthermore, θ° is divisible by 360°.

[0013] Furthermore, the metal sample must be cleaned with acetone solution before laser cladding and before laser cladding is performed in the annular groove.

[0014] Furthermore, during the laser cladding process described in step S2, an inert gas is introduced as a protective gas.

[0015] Furthermore, the metal plate has a length of 80-150mm, a width of 15-30mm, and a thickness of ≥1mm.

[0016] The crack resistance evaluation device includes a base plate, a base plate disposed at the top of the base plate and having a circular hole at its center, and a cylinder disposed at the center of the base plate and forming an annular groove with the base plate and the base plate. The depth of the annular groove can be adjusted by the thickness of the base plate and the cylinder, and the width of the annular groove can be adjusted by the diameter of the circular hole and the cylinder. The materials of the base plate, the base plate and the cylinder are the same as the materials of the metal sample.

[0017] Furthermore, the base plate has a length of 75-300mm, a width of 75-300mm, and a thickness of ≥2mm; the substrate has a length of 50-200mm, a width of 50-200mm, a thickness of ≥2mm, and a diameter of ≥20mm for the circular hole; and the cylinder has a diameter of ≥10mm and a thickness of ≥2mm.

[0018] Furthermore, mounting holes are provided around the perimeter of the substrate and at the center of the cylinder, and fasteners for connecting the base plate are provided at the mounting holes of both the substrate and the cylinder.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0020] (1) This invention targets the crack resistance of materials in the laser cladding additive manufacturing process. Laser cladding of single or multiple layers of additive manufacturing is carried out in the space of an annular groove. Unlike the evaluation method of laser cladding surface modification, crack sources are not pre-set. Instead, the sidewall of the annular groove exerts tensile stress on the solidified cladding layer, causing cracking, thereby evaluating the crack resistance of the material. It is highly targeted. By selecting different metal materials for laser cladding and measuring their crack rate, the crack resistance of laser cladding additive manufacturing of different metal materials can be evaluated, and the evaluation results are reliable.

[0021] (2) The crack resistance evaluation device of the present invention has a simple overall structure and is easy to operate during laser cladding. The dimensions of the substrate, cylinder and base plate can be flexibly set according to actual requirements. The depth of the annular groove can be adjusted by changing the thickness of the substrate and cylinder, thereby achieving the adjustment of the restraint. The deeper the annular groove, the greater the restraint of the cladding layer.

[0022] (3) The method for calculating the crack rate in this invention is rigorous, accurate and convenient. It takes into account the difference in crack rate at different sampling positions of the cladding layer in the annular groove, which is conducive to improving the reliability of the crack resistance evaluation results of laser cladding additive manufacturing. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the crack resistance evaluation device of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0025] Example 1

[0026] The present invention provides a method for evaluating the crack resistance of laser cladding additive manufacturing materials, comprising the following steps:

[0027] S1: Select a metal sample made of a laser cladding additive manufacturing material to be evaluated. Clean the metal sample with acetone solution to remove water, oil, and other contaminants from its surface. Perform laser cladding on the surface of the metal sample, introducing an inert gas as a protective gas during the laser cladding process to obtain a test cladding layer. Measure and calculate the width of the test cladding layer, and use this width as the cladding width of the metal material. Select multiple locations on the test cladding layer and measure the width at each location. Calculate the average width of all sampling points and use this as the cladding width. Preferably, multiple locations for width measurement are selected at equal intervals. Preferably, the length of the metal sample is 80-150 mm, the width is 15-30 mm, and the thickness is ≥1 mm. The cladding metal powder can be selected from composite powders (such as carbides, nitrides, etc.), copper-based alloy powders, titanium-based alloy powders, magnesium-based alloy powders, aluminum-based alloy powders, nickel-based alloy powders, and cobalt-based alloy powders, etc.

[0028] S2: Construct a crack resistance evaluation device with an annular groove 4. The material of the crack resistance evaluation device is the same as that of the metal sample in step S1. The width of the annular groove is the same as the cladding width. Clean the crack resistance evaluation device with acetone solution to remove water, oil and other contaminants from its surface. Use the same cladding powder as in step S1 to perform single-layer or multi-layer laser cladding additive manufacturing along an annular trajectory in the annular groove 4. During the laser cladding additive manufacturing process, an inert gas is introduced as a protective gas. Finally, the metal material is obtained as the cladding layer of the laser cladding additive manufacturing material.

[0029] like Figure 1 As shown, the crack resistance evaluation device includes a base plate 3, a base plate 2, and a cylinder 1. A circular hole is opened at the center of the base plate 2, and the cylinder 1 is located at the center of the circular hole in the base plate 2. Mounting holes are opened around the base plate 2 and at the center of the cylinder 1. Fasteners for connecting the base plate 3 are provided at the mounting holes of the base plate 2 and the cylinder 1. That is, the base plate 2 and the cylinder 1 are mounted on the top of the base plate 3 through the mounting holes and fasteners, so as to achieve a tight connection between the three and avoid thermal deformation of the device due to high energy during the laser cladding additive manufacturing process. In practical applications, the tight connection of the three is not limited to the use of fasteners through holes, and welding or integral forming of the device can also be considered. The circular hole, the base plate 3, and the cylinder 1 form an annular groove for laser cladding additive manufacturing. Preferably, the base plate 3 has a length of 75-300mm, a width of 75-300mm, and a thickness of ≥2mm; the substrate 2 has a length of 50-200mm, a width of 50-200mm, a thickness of ≥2mm, a diameter of ≥20mm for the circular hole; and the cylinder 1 has a diameter of ≥10mm and a thickness of ≥2mm.

[0030] The depth of the annular groove 4 can be adjusted by the thickness of the substrate 2 and the cylinder 1. The deeper the annular groove, the greater the constraint on the cladding layer. The width of the annular groove 4 can be adjusted by the diameter of the circular hole and the cylinder 1. The materials of the base plate 3, the substrate 2, and the cylinder 1 are the same as the materials of the metal sample.

[0031] S3: Take cross-sections of the cladding layer at intervals of θ° from the starting position of laser cladding. Preferably, θ° is divisible by 360°. Measure the total crack length and height of each cross-section, calculate the individual crack rate of each cross-section, and calculate the average of all individual crack rates as the final crack rate of the material. The formula for calculating the individual crack rate is:

[0032]

[0033] S4: For the various laser cladding additive manufacturing materials to be evaluated, repeat steps S1-S3 under the same test conditions to obtain the final crack rate of each laser cladding additive manufacturing material, and rank the final crack rates of the various laser cladding additive manufacturing materials. The laser cladding additive manufacturing material with the lower crack rate has stronger crack resistance.

[0034] Example 2

[0035] In this embodiment, Ni60A powder was selected as the cladding powder, and 304 stainless steel, 310 stainless steel and 316 stainless steel were used as the materials for the metal sample and the crack resistance evaluation device, respectively, to evaluate the crack resistance of different materials in laser cladding additive manufacturing.

[0036] Prepare metal samples corresponding to 304 stainless steel, 310 stainless steel, and 316 stainless steel respectively. Use wire cutting to prepare test cladding metal samples for each of the three stainless steel materials. The length, width, and thickness of the three metal samples are identical. Y The width is 80mm, and the width is (W). Y The thickness is 20mm, and the thickness (H) is 20mm. Y The value is 2mm.

[0037] Three metal samples were cleaned with acetone solution to remove water and oil from their surfaces.

[0038] Laser cladding was employed, with experimental parameters set as follows: laser power 1.5 kW, scanning speed 3 mm / s, and powder feed rate 18 g / min. During the laser cladding process, 99.9999% pure argon gas was introduced as a protective gas at a flow rate of 15 L / min. Argon gas was continuously introduced for 10 seconds before and after the start and end of the laser cladding process. A rectangular laser spot measuring 5 mm × 5 mm was moved to the starting position of the laser cladding process, and laser cladding was performed on three metal samples. The test cladding length was 60 mm, resulting in a test cladding layer.

[0039] After the three metal samples cooled, the width of the trial cladding layer was measured at three equal points on each metal sample, starting from the laser cladding start point. The average width (W) of the trial cladding layer for each metal sample was then calculated based on the measured widths. p From this, the average width (W) of the 304 stainless steel trial cladding layer was calculated. p1 The average width (W) of the 310 stainless steel trial cladding layer is 11.5 mm. p2 The average width (W) of the 316 stainless steel trial cladding layer is 13mm. p3 The width of the annular groove 4 is 12.4 mm. a ) and the average width of the test cladding layer (W) p )equal.

[0040] Continuing with wire cutting, corresponding crack resistance evaluation devices were prepared using three different types of stainless steel materials. Specifically, base plates 3, substrates 2, and cylinders 1 were prepared using three different stainless steel materials. The three substrates 2 had a length (Lz) of 100mm, a width (Wz) of 100mm, a diameter (Dz) of 30mm for the circular hole, and a thickness (Hz) of 3mm. The three base plates 3 had a length (Ld) of 200mm, a width (Wd) of 200mm, and a thickness (H) of 3mm. d The diameter of cylinder 1 is 5mm; while the diameter of cylinder 1 (D) is 5mm. L ) and the width (W) of the constructed annular groove 4 a Regarding the diameter (D) of the cylinder 1 used in 304 stainless steel... L1 The diameter (D) of the cylinder 1 used in 310 stainless steel is 18.5mm. L2 The diameter (D) of the cylinder 1 used in 316 stainless steel is 17mm. L3 The thickness of the three sets of cylinders 1 is 17.6 mm; L All are 3mm deep; the final three sets of evaluation devices are all 3mm deep, the annular groove 4 of the three sets of evaluation devices is 11.5mm wide, the annular groove 4 of the 304 stainless steel is 13mm wide, and the annular groove 4 of the 310 stainless steel is 12.4mm wide.

[0041] Through holes with a diameter of 5mm were drilled around the perimeter of the substrate 2 and at the center of the cylinder 1 in each group. M5 threaded holes were drilled on the three base plates 3 at positions corresponding to the through holes. The three base plates 3, substrate 2, and cylinder 1 were cleaned with acetone solution to remove water and oil. The substrate 2 and cylinder 1 were fixed to the corresponding base plates 3 with M5 bolts to obtain three sets of crack resistance evaluation devices for different stainless steel materials.

[0042] The experimental parameters for the laser cladding process were kept consistent with those for the trial cladding test. A 5mm × 5mm rectangular laser spot was moved to any starting point on the annular groove 4, and laser cladding was performed along a preset annular path, cladding two layers successively. After the first layer was clad, the second layer was clad along the same annular path. Under the action of the laser heat source, Ni60A powder melted and uniformly clad onto the surface of the three stainless steel materials. However, due to the restriction of the sidewalls of the annular groove 4, the normal shrinkage process of the cladding layer was hindered, leading to the generation and continuous propagation of cracks.

[0043] After the three sets of crack resistance evaluation devices cooled down, the cross-section of the cladding layer was sampled every 60° along the starting position of the laser cladding. The total crack length (Lc) and cross-sectional height (Hc) of the cross-section were measured. Based on the measured data, the individual crack rate of each cross-section was calculated. The crack rate (δ) of the three stainless steel materials was obtained by averaging the individual crack rates of each cross-section.p Calculations show that the crack rate for 304 stainless steel is 58.6%, for 310 stainless steel it is 78.6%, and for 316 stainless steel it is 65.7%.

[0044] The crack rates of three stainless steel materials obtained under the same conditions were ranked to evaluate their crack resistance. The results showed that 304 stainless steel > 316 stainless steel > 310 stainless steel, thus achieving the evaluation of crack resistance in laser cladding additive manufacturing.

[0045] Example 3

[0046] In this embodiment, WC powder was selected as the cladding powder, and 2024 aluminum alloy, 5083 aluminum alloy and 6061 aluminum alloy were used as the materials for the metal templates and crack resistance evaluation device, respectively, to evaluate the crack resistance of different materials in laser cladding additive manufacturing.

[0047] Prepare metal templates for three aluminum alloys: 2024, 5083, and 6061. Use wire cutting to fabricate test cladding templates for each of the three alloys. The length, width, and thickness of the three templates should be identical. Y The width is 150mm, and the width is (W). Y The thickness is 30mm, and the thickness (H) is 30mm. Y The value is 3mm.

[0048] Three metal samples were cleaned with acetone solution to remove water and oil from their surfaces.

[0049] Laser cladding was employed, with experimental parameters set as follows: laser power 3kW, scanning speed 6mm / s, and powder feed rate 25g / min. During the laser cladding process, 99.9999% pure argon gas was introduced as a protective gas at a flow rate of 15L / min. Argon gas was continuously introduced for 10s before and after the start and end of the laser cladding process. A rectangular laser spot of 4mm × 4mm was moved to the starting position of the laser cladding process, and laser cladding was performed on three metal samples. The test cladding length was 120mm, resulting in a test cladding layer.

[0050] After the three metal samples cooled, the width of each sample was measured at five equal divisions starting from the laser cladding start point. The width of the test cladding layer was then measured, and the average width (W) of the test cladding layer for each metal sample was calculated based on the measured widths. p From this, the average width (W) of the 2024 aluminum alloy cladding layer was calculated. p1 The average width (W) of the 5083 aluminum alloy cladding layer is 8.3 mm. p2 The average width (W) of the 6061 aluminum alloy cladding layer is 7.8 mm. p3The width of the annular groove 4 is 8.5mm. a ) and the average width of the test cladding layer (W) p )equal.

[0051] Continuing with wire cutting, corresponding crack resistance evaluation devices were prepared using three types of stainless steel materials, namely, base plates 3, substrates 2, and cylinders 1 made of three different aluminum alloy materials. The lengths (L) of the three sets of substrates 2 are... z ) is 200mm, width (W) z The diameter of the circular hole is 200mm (D). z ) is 50mm, thickness (H) z The length of the three sets of base plates (L) is 4mm; d ) is 300mm, width (W) d ) is 300mm, thickness (H) d The diameter of cylinder 1 is 6mm; while the diameter of cylinder 1 (D) is 6mm. L ) and the width (W) of the constructed annular groove 4 a Regarding the diameter (D) of cylinder 1 used in 2024 aluminum alloy... L1 The diameter (D) of cylinder 1 used in 5083 aluminum alloy is 41.7mm. L2 The diameter (D) of the cylinder 1 used in 6061 aluminum alloy is 42.2mm. L3 The thickness of the three sets of cylinders 1 is 41.5 mm; L All are 4mm deep; the final three evaluation devices are constructed with annular grooves 4 of 4mm deep, 8.3mm wide for the annular grooves 4 made of 2024 aluminum alloy, 7.8mm wide for the annular grooves 4 made of 5083 aluminum alloy, and 8.5mm wide for the annular grooves 4 made of 6061 aluminum alloy.

[0052] Through holes with a diameter of 8 mm were drilled around the perimeter of the substrate 2 and at the center of the cylinder 1 in each group. M8 threaded holes were drilled on the three base plates 3 at positions corresponding to the through holes. The three base plates 3, substrate 2, and cylinder 1 were cleaned with acetone solution to remove water and oil. The substrate 2 and cylinder 1 were fixed to the corresponding base plates 3 with M5 bolts to obtain three different crack resistance evaluation devices.

[0053] The experimental parameters for the laser cladding process were kept consistent with those for the trial cladding test. A 4mm × 4mm rectangular laser spot was moved to any starting point on the annular groove 4, and laser cladding was performed along a preset annular path, cladding two layers successively. After the first layer was clad, the second layer was clad along the same annular path. Under the action of the laser heat source, the WC powder melted and uniformly clad onto the surface of the three aluminum alloy materials. However, because the sidewalls of the annular groove 4 hindered the normal shrinkage of the cladding layer, cracks were generated and continued to propagate.

[0054] After the three sets of crack resistance evaluation devices cooled down, cross-sections of the cladding layer were cut at 90° intervals along the initial cladding position. The total crack length (Lc) and cross-sectional height (Hc) of each cross-section were measured. Based on the measured data, the individual crack rate of each cross-section was calculated. The crack rate (δp) of the three aluminum alloys was obtained by averaging the individual crack rates of each cross-section. The calculated crack rate was 46.5% for 2024 aluminum alloy, 36.8% for 5083 aluminum alloy, and 60.7% for 6061 aluminum alloy.

[0055] The crack rates of three aluminum alloys obtained under the same conditions were ranked to evaluate their crack resistance. The results showed that 5083 aluminum alloy > 2024 aluminum alloy > 6061 aluminum alloy, thus achieving the evaluation of crack resistance in laser cladding additive manufacturing.

Claims

1. A method for evaluating the crack resistance of laser cladding additive manufacturing materials, characterized in that: Includes the following steps: S1: Select a metal sample made of a laser cladding additive manufacturing material to be evaluated, perform laser cladding on the surface of the metal sample to obtain a test cladding layer, measure and calculate the width of the test cladding layer, and take the width of the test cladding layer as the cladding width of the metal material; S2: Construct a crack resistance evaluation device with an annular groove (4). The material of the crack resistance evaluation device is the same as that of the metal sample in step S1. The width of the annular groove (4) is consistent with the cladding width. The same cladding powder as in step S1 is used. Single-layer or multi-layer laser cladding additive manufacturing is carried out in the annular groove (4) along the annular trajectory to obtain the metal material as the cladding layer of the laser cladding additive manufacturing material. S3: Take cross-sections of the cladding layer every θ° from the starting position of laser cladding, measure the total crack length and height of each cross-section, calculate the individual crack rate of each cross-section, and calculate the average of all individual crack rates as the final crack rate of the metal material. S4: For the various laser cladding additive manufacturing materials to be evaluated, repeat steps S1-S3 under the same test conditions to obtain the final crack rate of the various laser cladding additive manufacturing materials, and rank the final crack rates of the various laser cladding additive manufacturing materials.

2. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: The method for obtaining the cladding width in step S1 is as follows: select multiple locations of the test cladding layer, measure the width of each location, calculate the average width of all sampling points, and use it as the cladding width.

3. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: The formula for calculating the individual crack rate in step S3 is:

4. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: The given θ° is divisible by 360°.

5. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: Metal samples must be cleaned with acetone solution before laser cladding and before laser cladding in the annular groove.

6. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: In the laser cladding process described in step S2, an inert gas is introduced as a protective gas.

7. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: The metal template has a length of 80-150mm, a width of 15-30mm, and a thickness of ≥1mm.

8. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 1, characterized in that: The crack resistance evaluation device includes a base plate (3), a base plate (2) with a circular hole at the top of the base plate (3) and a cylinder (1) at the center of the base plate (2) and forming an annular groove (4) with the base plate (2) and the base plate (3). The depth of the annular groove (4) can be adjusted by the thickness of the base plate (2) and the cylinder (1), and the width of the annular groove (4) can be adjusted by the diameter of the circular hole and the cylinder (1). The materials of the base plate (3), the base plate (2) and the cylinder (1) are the same as the materials of the metal sample.

9. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 8, characterized in that: The base plate (3) has a length of 75-300mm, a width of 75-300mm, and a thickness of ≥2mm. The substrate (2) has a length of 50-200mm, a width of 50-200mm, a thickness of ≥2mm, and a diameter of ≥20mm for the circular hole. The cylinder (1) has a diameter of ≥10mm and a thickness of ≥2mm.

10. The method for evaluating the crack resistance of laser cladding additive manufacturing materials according to claim 9, characterized in that: Mounting holes are provided around the base plate (2) and at the center of the cylinder (1), and fasteners for connecting the base plate (3) are provided at the mounting holes of the base plate (2) and the cylinder (1).

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