A preparation method of a carbon and nitrogen assisted laser strengthened wear-resistant layer

Abstract

The present invention provides a method for preparing a carbon-nitride-assisted laser-strengthened wear-resistant layer, comprising: Step A, first, dividing the surface of the alloy to be treated into a structure with a base region and a strengthening region spaced apart from each other, and coating the surface of each strengthening region with a carbon layer structure; Step B, placing the alloy sample in a sealed glass container, and sequentially introducing nitrogen gas and liquid nitrogen; Step C, using a laser head to laser-melt the strengthening regions; and Step D, repeating Step C to complete the carbonitriding laser strengthening of all strengthening regions. This method targets the surface of alloy steel with low carbon content through laser melting and strengthening, utilizing the principles of carbonitriding to modify and strengthen the low-carbon alloy surface, resulting in the alloy surface exhibiting excellent wear resistance and fatigue resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of surface wear-resistant protection, and in particular to a method for preparing a carbon-nitrogen assisted laser-strengthened wear-resistant layer. Background Art

[0002] The two main factors affecting the service life of alloy steel mechanical motion parts are wear and fatigue. In the existing technology, in order to improve the service life and usage strength of parts, the surface of the parts is usually modified or strengthened.

[0003] Laser surface modification technology is a new surface engineering technology that uses laser radiation to induce a series of physical and chemical reactions on the surface of a material, thereby enhancing its performance. Compared to traditional surface modification technologies, laser surface modification technology has the advantages of high energy density, concentrated heat output, and environmental friendliness. It mainly includes laser surface quenching, laser melting, laser alloying, and laser cladding. Among them, laser melting technology involves scanning the workpiece surface with a high-energy laser beam, rapidly increasing the surface temperature of the material, and then rapidly cooling it by the material itself to achieve the purpose of strengthening the material. After strengthening, the surface hardness, wear resistance, and thermal fatigue resistance of the material are significantly improved.

[0004] Currently, laser melting technology has been used to strengthen high-carbon alloy steels such as 40Cr, 40CrNiMo, 5CrNiMo, and 45 steel. The wear and thermal fatigue resistance of the strengthened alloy steels has been significantly improved. Research has also shown that the higher the carbon equivalent of the alloy steel, the greater the microhardness of the strengthened unit cell, and the better the wear and thermal fatigue resistance. However, for alloy steels with lower carbon contents, such as AF1410 and 17-4PH, direct laser melting strengthening has poor surface modification effects due to the low carbon content. The surface hardness of the strengthened surface is not significantly improved, and it is impossible to achieve a significant improvement in the material's surface hardness, wear resistance, and other properties. Summary of the Invention

[0005] In response to the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a carbon-nitrogen-assisted laser-strengthened wear-resistant layer. This method performs laser melting and strengthening modification on the surface of alloy steel with a low carbon content, and utilizes the principle of carbonitriding to modify and strengthen the surface of the low-carbon alloy, so that the alloy surface exhibits excellent wear resistance and fatigue resistance.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a carbon-nitride assisted laser-strengthened wear-resistant layer, characterized by comprising the following steps:

[0008] Step A: First, the surface to be strengthened of the alloy to be treated is divided into a modified structure surface with a matrix area and a strengthening area spaced apart from each other; then, a carbon layer structure is coated on the surface of each strengthening area to obtain an alloy sample;

[0009] Step B: placing the alloy sample treated in step A in a sealed glass container, then first introducing nitrogen into the sealed glass container, and after the sealed glass container is filled with nitrogen, stopping the introduction of nitrogen, and then introducing liquid nitrogen into the sealed glass container;

[0010] Step C: Using a manipulator to control the laser emitting end of the laser head of the laser melting device to align with the strengthening area of ​​the alloy sample that has not been laser treated in the sealed glass container, with the laser head located on the upper side of the sealed glass container, setting the parameters of the laser melting device, starting the laser melting device, and simultaneously controlling the translation of the laser head by the manipulator to achieve carbonitriding laser strengthening of the strengthening area of ​​the alloy sample; during the laser melting process, maintaining continuous flow of liquid nitrogen;

[0011] Step D: repeat step C until the carbonitriding laser strengthening of all strengthening zones is completed to obtain a surface-modified alloy.

[0012] Based on further optimization of the above solution, the alloy to be treated is steel with a low carbon content, such as AF1410 and 17-4PH.

[0013] Based on further optimization of the above solution, the width of the base area, that is, the distance between two adjacent strengthening areas, is 3 to 6 mm.

[0014] Based on further optimization of the above solution, the carbon layer structure is a carbon powder slurry composed of one or more carbon-containing materials selected from carbon powder, graphene or graphene oxide; the thickness of the carbon layer structure is 50 to 150 μm.

[0015] Based on further optimization of the above scheme, the preparation process of the carbon layer structure is: dissolving the carbon-containing material in an alcohol solution, stirring and mixing thoroughly to form a carbon powder slurry for coating; wherein the mass ratio of the carbon-containing material to the alcohol solution is 2.5-3.5:1.5-2.5.

[0016] Based on the further optimization of the above scheme, the sealed glass container is a rectangular structure, and a partition plate parallel to the top surface is set in the middle of its inner cavity, and the partition plate is used to place the alloy sample; a nitrogen inlet pipe and a liquid nitrogen inlet pipe are respectively set on the side of one side of the sealed glass container and located under the partition plate, and a nitrogen outlet pipe is set on the side of the sealed glass container corresponding to the nitrogen inlet pipe and located on the upper side of the partition plate; a plurality of ventilation holes are evenly arranged on the partition plate and around the alloy sample.

[0017] Based on further optimization of the above scheme, the flow rates of the nitrogen gas and liquid nitrogen are both 1 L / min to 3 L / min.

[0018] Based on further optimization of the above solution, the parameters of the laser melting equipment are specifically as follows: power 400W to 1000W, spot diameter 2mm, defocusing amount 2cm, scanning speed 2mm / s to 15mm / s.

[0019] The following are the effects of the above technical solution of the present invention:

[0020] This application divides the surface of the alloy to be treated into a matrix area and a strengthening area, uses a carbon layer structure and nitrogen and liquid nitrogen to provide carbon and nitrogen sources respectively, and uses laser melting technology to achieve carbonitriding and laser strengthening of the surface of low-carbon steel, thereby significantly improving the hardness of the alloy surface. By dividing the matrix area and the strengthening area, firstly, a soft-hard alternating distribution is achieved on the alloy surface after laser strengthening, thereby effectively improving the wear resistance of the alloy surface; secondly, by coordinating the matrix area and the strengthening area, the matrix area is used to buffer the energy of the laser strengthening process, avoiding problems such as crack propagation and extension during the laser treatment process, and effectively ensuring the hardness and strength of the alloy surface after laser strengthening.

[0021] In addition, during the laser strengthening process, the present application adopts the method of first introducing nitrogen and then introducing liquid nitrogen. First, the air in the sealed glass container is preferentially discharged through nitrogen to avoid the liquefaction of water vapor in the air to form white mist during the process of liquid nitrogen vaporization to form nitrogen, which affects the laser emission, resulting in poor strengthening effect and even safety hazards; second, the flow of liquid nitrogen is used to cool the alloy sample, accelerate the cooling rate of the strengthening zone, and avoid deformation due to excessive temperature of the alloy matrix, thereby achieving the purpose of refining the grains and enhancing the surface strength of the alloy sample; third, the nitrogen formed after the liquid nitrogen absorbs heat and vaporizes continuously and uninterruptedly provides a nitrogen source for the strengthening zone in the laser strengthening process, thereby ensuring the effectiveness of carbonitriding; fourth, the nitrogen formed by the continuous and uninterrupted flow of liquid nitrogen is used as an inert protective gas to avoid oxidation of the strengthening zone and the surrounding alloys during the laser strengthening process, effectively improve the surface quality and hardness of the strengthening zone, and avoid oxidation and burning of the carbon source during the laser strengthening process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure in which an alloy sample is placed in a sealed glass container for laser melting in an embodiment of the present invention.

[0023] Among them, 10. Sealed glass container; 11. Partition plate; 110. Vent; 12. Nitrogen inlet pipe; 13. Liquid nitrogen inlet pipe; 14. Nitrogen outlet pipe; 20. Alloy specimen; 21. Matrix area; 22. Strengthening area; 30. Laser head. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] Example 1:

[0026] For alloy sample 20 made of AF1410 low carbon steel, a method for preparing a carbon-nitrogen-assisted laser-strengthened wear-resistant layer comprises the following steps:

[0027] Step A: First, the surface to be strengthened of AF1410 alloy steel is divided into a modified structure surface with a base area 21 and a strengthening area 22 spaced apart from each other, such as Figure 1 The width of the matrix area 21, ie, the spacing between two adjacent strengthening areas 22 is 3 mm.

[0028] Then, a carbon layer structure with a thickness of 50 μm was coated on the surface of each strengthening area 22 to obtain an AF1410 alloy steel sample; the carbon layer structure was a carbon powder slurry composed of carbon powder, and the preparation method of the carbon powder slurry was specifically as follows: carbon powder was dissolved in an alcohol solution, and after sufficient stirring and mixing, a carbon powder slurry for coating was formed; wherein the mass ratio of carbon powder to alcohol solution was 2.5:1.5.

[0029] Step B: Place the AF1410 alloy steel sample processed in step A in a sealed glass container 10. The sealed glass container 10 is a rectangular parallelepiped structure, and a partition plate 11 parallel to the top surface is set in the middle of the inner cavity. The partition plate 11 is used to place the alloy sample 20. In this embodiment: the AF1410 alloy steel sample is placed on the end surface of the partition plate 11; one side of the sealed glass container 10 (i.e. Figure 1 The left side is shown) and the nitrogen inlet pipe 12 and the liquid nitrogen inlet pipe 13 are respectively provided on the lower side of the partition plate 11, and the sealed glass container 10 and the nitrogen inlet pipe 12 are on the corresponding side (i.e. Figure 1 A nitrogen outlet pipe 14 is provided on the partition plate 11 (as shown on the right side) and on the upper side of the partition plate 11; a plurality of vent holes 110 are evenly provided on the partition plate 11 and around the AF1410 alloy steel sample (the aperture of the vent holes 110 is set according to actual conditions, and it is necessary to ensure the passage of nitrogen and the balance of nitrogen flow. At the same time, the vent holes 110 are opened according to the size of the alloy sample 20).

[0030] Then, nitrogen is first introduced into the sealed glass container 10 through the nitrogen inlet pipe 12 at a nitrogen flow rate of 1 L / min. After the sealed glass container 10 is filled with nitrogen (air is discharged through the nitrogen outlet pipe 14, and a nitrogen concentration detector can be set at the nozzle of the nitrogen outlet pipe 14 to detect whether the sealed glass container 10 is full of nitrogen), the nitrogen introduction is stopped, and liquid nitrogen is then introduced into the sealed glass container 10 at a flow rate of 1 L / min;

[0031] Step C: Use a robot to control the laser emitting end of the laser head 30 of the laser melting equipment to align with the untreated strengthened area 22 of the AF1410 alloy steel sample in the sealed glass container 10. The laser head 30 is located on the upper side of the sealed glass container 10 and can emit laser light toward the strengthened area 22 through the top glass of the sealed glass container 10. Set the parameters of the laser melting equipment, specifically: power 400 W, spot diameter 2 mm, defocus 2 cm, and scanning speed 2 mm / s.

[0032] The laser melting equipment was started and the laser head 30 was controlled to move horizontally by a manipulator to achieve carbonitriding laser strengthening of the strengthening zone 22 of the AF1410 alloy steel sample. During the laser melting process, liquid nitrogen was continuously introduced at a flow rate of 1 L / min.

[0033] Step D: repeat step C until the carbonitriding laser strengthening of all the strengthening zones 22 is completed to obtain the surface-modified AF1410 alloy steel.

[0034] Example 2:

[0035] For alloy sample 20 made of 17-4PH low carbon steel, a method for preparing a wear-resistant layer by carbon-nitrogen-assisted laser strengthening is provided, comprising the following steps:

[0036] Step A: First, the surface to be strengthened of 17-4PH alloy steel is divided into a modified structure surface with a base area 21 and a strengthening area 22 spaced apart from each other, such as Figure 1 The width of the matrix area 21, ie, the spacing between two adjacent strengthening areas 22 is 4.5 mm.

[0037] Then, a carbon layer structure with a thickness of 100 μm is coated on the surface of each strengthening zone 22 to obtain a 17-4PH alloy steel sample; the carbon layer structure is a carbon powder slurry composed of a mixture of graphene and graphene oxide, and the mass ratio of graphene to graphene oxide is 2 to 4:1 (preferably 3:1). The preparation method of the carbon powder slurry is specifically as follows: graphene and graphene oxide are mixed according to a mass ratio to obtain a carbon-containing material mixture, the carbon-containing material mixture is dissolved in an alcohol solution, and after sufficient stirring and mixing, a carbon powder slurry for coating is formed; wherein the mass ratio of the carbon-containing material mixture to the alcohol solution is 3:2.

[0038] Step B: Place the 17-4PH alloy steel sample processed in step A in a sealed glass container 10. The sealed glass container 10 is a rectangular parallelepiped structure, and a partition plate 11 parallel to the top surface is set in the middle of the inner cavity. The partition plate 11 is used to place the alloy sample 20. In this embodiment: the 17-4PH alloy steel sample is placed on the end surface of the partition plate 11; one side of the sealed glass container 10 (i.e. Figure 1The left side is shown) and the nitrogen inlet pipe 12 and the liquid nitrogen inlet pipe 13 are respectively provided on the lower side of the partition plate 11, and the sealed glass container 10 and the nitrogen inlet pipe 12 are on the corresponding side (i.e. Figure 1 A nitrogen outlet pipe 14 is provided on the partition plate 11 (as shown on the right side) and on the upper side of the partition plate 11; a plurality of vent holes 110 are evenly provided on the partition plate 11 and around the 17-4PH alloy steel sample (the aperture of the vent holes 110 is set according to actual conditions to ensure the passage of nitrogen and the balance of nitrogen flow; at the same time, the vent holes 110 are opened according to the size of the alloy sample 20).

[0039] Then, nitrogen is first introduced into the sealed glass container 10 through the nitrogen inlet pipe 12 at a nitrogen flow rate of 2 L / min. After the sealed glass container 10 is filled with nitrogen (air is discharged through the nitrogen outlet pipe 14, and a nitrogen concentration detector can be set at the nozzle of the nitrogen outlet pipe 14 to detect whether the sealed glass container 10 is full of nitrogen), the nitrogen introduction is stopped, and liquid nitrogen is then introduced into the sealed glass container 10 at a flow rate of 2 L / min;

[0040] Step C: Use a robot to control the laser emitting end of the laser head 30 of the laser melting equipment to align with the untreated strengthened area 22 of the 17-4PH alloy steel sample in the sealed glass container 10. The laser head 30 is located on the upper side of the sealed glass container 10 and can emit laser light toward the strengthened area 22 through the top glass of the sealed glass container 10. Set the laser melting equipment parameters, specifically: power 700 W, spot diameter 2 mm, defocus 2 cm, and scanning speed 10 mm / s.

[0041] The laser melting equipment was started, and the laser head 30 was controlled to move horizontally by a manipulator to achieve carbonitriding laser strengthening of the strengthening area 22 of the 17-4PH alloy steel sample. During the laser melting process, liquid nitrogen was continuously introduced at a flow rate of 1 L / min.

[0042] Step D: repeat step C until the carbonitriding laser strengthening of all the strengthening zones 22 is completed to obtain the surface-modified 17-4PH alloy steel.

[0043] Example 3:

[0044] For alloy sample 20 made of AF1410 low carbon steel, a method for preparing a carbon-nitrogen-assisted laser-strengthened wear-resistant layer comprises the following steps:

[0045] Step A: First, the surface to be strengthened of AF1410 alloy steel is divided into a modified structure surface with a base area 21 and a strengthening area 22 spaced apart from each other, such as Figure 1 The width of the matrix area 21, ie, the spacing between two adjacent strengthening areas 22 is 6 mm.

[0046] Then, a carbon layer structure with a thickness of 150 μm was coated on the surface of each strengthening area 22 to obtain an AF1410 alloy steel sample; the carbon layer structure was a carbon powder slurry composed of graphene, and the preparation method of the carbon powder slurry was specifically as follows: dissolving graphene in an alcohol solution, stirring and mixing thoroughly to form a carbon powder slurry for coating; wherein the mass ratio of graphene to alcohol solution was 3.5:2.5.

[0047] Step B: Place the AF1410 alloy steel sample processed in step A in a sealed glass container 10. The sealed glass container 10 is a rectangular parallelepiped structure, and a partition plate 11 parallel to the top surface is set in the middle of the inner cavity. The partition plate 11 is used to place the alloy sample 20. In this embodiment: the AF1410 alloy steel sample is placed on the end surface of the partition plate 11; one side of the sealed glass container 10 (i.e. Figure 1 The left side is shown) and the nitrogen inlet pipe 12 and the liquid nitrogen inlet pipe 13 are respectively provided on the lower side of the partition plate 11, and the sealed glass container 10 and the nitrogen inlet pipe 12 are on the corresponding side (i.e. Figure 1 A nitrogen outlet pipe 14 is provided on the partition plate 11 (as shown on the right side) and on the upper side of the partition plate 11; a plurality of vent holes 110 are evenly provided on the partition plate 11 and around the AF1410 alloy steel sample (the aperture of the vent holes 110 is set according to actual conditions, and it is necessary to ensure the passage of nitrogen and the balance of nitrogen flow. At the same time, the vent holes 110 are opened according to the size of the alloy sample 20).

[0048] Then, nitrogen is first introduced into the sealed glass container 10 through the nitrogen inlet pipe 12 at a nitrogen flow rate of 3 L / min. After the sealed glass container 10 is filled with nitrogen (air is discharged through the nitrogen outlet pipe 14, and a nitrogen concentration detector can be set at the nozzle of the nitrogen outlet pipe 14 to detect whether the sealed glass container 10 is full of nitrogen), the nitrogen introduction is stopped, and liquid nitrogen is then introduced into the sealed glass container 10 at a flow rate of 3 L / min;

[0049] Step C: Use a robot to control the laser emitting end of the laser head 30 of the laser melting equipment to align with the untreated strengthened area 22 of the AF1410 alloy steel sample in the sealed glass container 10. The laser head 30 is located on the upper side of the sealed glass container 10 and can emit laser light toward the strengthened area 22 through the top glass of the sealed glass container 10. Set the parameters of the laser melting equipment, specifically: power of 1000 W, spot diameter of 2 mm, defocus of 2 cm, and scanning speed of 15 mm / s.

[0050] The laser melting equipment was started and the laser head 30 was controlled to move horizontally by a manipulator to achieve carbonitriding laser strengthening of the strengthening zone 22 of the AF1410 alloy steel sample. During the laser melting process, liquid nitrogen was continuously introduced at a flow rate of 1 L / min.

[0051] Step D: repeat step C until the carbonitriding laser strengthening of all the strengthening zones 22 is completed to obtain the surface-modified AF1410 alloy steel.

Claims

1. A method for preparing a carbon-nitrogen assisted laser-strengthened wear-resistant layer, characterized in that: The following steps are involved: Step A: First, the surface to be strengthened of the alloy to be treated is divided into a modified structure surface with a base area and a strengthening area spaced apart from each other; Then, a carbon layer structure is coated on the surface of each strengthening area to obtain an alloy sample; Step B, placing the alloy sample processed in step A in a sealed glass container, then first introducing nitrogen into the sealed glass container, and after the sealed glass container is filled with nitrogen, stopping the nitrogen introduction, and then introducing liquid nitrogen into the sealed glass container; the sealed glass container is a rectangular parallelepiped structure, and a partition plate parallel to the top surface is provided in the middle of its inner cavity, and the partition plate is used to place the alloy sample; a nitrogen inlet pipe and a liquid nitrogen inlet pipe are respectively provided on the side of one side of the sealed glass container and located below the partition plate, and a nitrogen outlet pipe is provided on the side of the sealed glass container corresponding to the nitrogen inlet pipe and located above the partition plate; a plurality of vents are evenly provided on the partition plate and around the alloy sample; the flow rates of nitrogen and liquid nitrogen are both 1L / min to 3L / min; Step C: Using a manipulator to control the laser emitting end of the laser head of the laser melting device to align with the strengthening area of ​​the alloy sample that has not been laser treated in the sealed glass container, with the laser head located on the upper side of the sealed glass container, setting the parameters of the laser melting device, starting the laser melting device, and simultaneously controlling the translation of the laser head by the manipulator to achieve carbonitriding laser strengthening of the strengthening area of ​​the alloy sample; during the laser melting process, maintaining continuous flow of liquid nitrogen; Step D: repeat step C until the carbonitriding laser strengthening of all strengthening zones is completed to obtain a surface-modified alloy.

2. The method for preparing a carbon-nitride assisted laser strengthened wear-resistant layer according to claim 1, characterized in that: The width of the base area, that is, the distance between two adjacent reinforcement areas, is 3 to 6 mm.

3. The method for preparing a carbon-nitride-assisted laser-strengthened wear-resistant layer according to claim 1 or 2, characterized in that: The carbon layer structure is a carbon powder slurry composed of one or more carbon-containing materials selected from carbon powder, graphene or graphene oxide; the thickness of the carbon layer structure is 50 to 150 μm.

4. The method for preparing a carbon-nitride-assisted laser-strengthened wear-resistant layer according to claim 3, characterized in that: The preparation process of the carbon layer structure is as follows: dissolving a carbon-containing material in an alcohol solution, stirring and mixing the mixture thoroughly to form a carbon powder slurry for coating; wherein the mass ratio of the carbon-containing material to the alcohol solution is 2.5-3.5:1.5-2.

5.

5. The method for preparing a carbon-nitride assisted laser strengthened wear-resistant layer according to claim 1, characterized in that: The parameters of the laser melting equipment are specifically as follows: power 400W-1000W, spot diameter 2mm, defocusing amount 2cm, scanning speed 2mm / s-15mm / s.

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