Cladding material for nano-reinforced gradient component cutter alloy steel

Abstract

The invention discloses a cladding material for nano-reinforced gradient component cutter alloy steel. The cladding material comprises basic alloy powder, a composite nano-reinforced phase and a gradient regulation and control additive, the basic alloy powder is an iron-based system and contains chromium, nickel, titanium, boron and niobium elements; the composite nano reinforced phase is a compound system of in-situ synthesis TiC and nano CBN; in the preparation process, selective laser gradient material distribution, segmented ball milling and vacuum passivation processes are adopted, it is ensured that the coating is tightly combined with the base body, and the requirements of tool use for wear resistance, corrosion resistance and high-temperature stability are met. According to the cladding material, through cooperation of gradient design and a core technology, the basic mechanical property and forming quality of a coating are remarkably improved, and the interface bonding strength and density are enhanced; the coating has excellent wear resistance, high-temperature stability and corrosion resistance and good storage performance.

Description

Technical Field

[0001] This invention relates to the field of cladding materials technology, specifically to a cladding material for nano-reinforced gradient composition tool alloy steel. Background Technology

[0002] Tool alloy steels are subjected to severe friction, impact, and high temperatures during cutting and grinding, making their surfaces highly susceptible to wear, deformation, and even failure. Laser cladding technology is crucial for creating reinforcing coatings on their surfaces to extend tool life. Current cladding materials for tool alloy steels primarily use a single iron-based alloy powder as the matrix, combined with single reinforcing phases such as tungsten carbide or titanium carbide. While this can improve surface hardness to some extent, several technical bottlenecks remain. Firstly, the reinforcing phases in traditional cladding materials are often externally doped, resulting in poor interfacial compatibility with the matrix and a tendency for agglomeration and segregation. This leads to stress concentration within the coating, hindering the formation of a stable metallurgical bond and causing the coating to peel off during service. Secondly, existing gradient cladding materials often employ a linear gradient distribution design, failing to balance the bonding strength between the coating and the matrix, the impact resistance in the center of the coating, and the wear resistance of the surface layer, making it difficult to meet the complex service requirements of cutting tools.

[0003] Furthermore, existing cladding materials suffer from insufficient high-temperature stability. Under high-temperature conditions, the reinforcing phase is prone to decomposition and growth, leading to a sharp decline in coating hardness and wear resistance. While some cladding materials incorporate rare earth oxides as additives, these are mostly single rare earth components, only achieving the single function of grain refinement and failing to synergistically regulate the in-situ generation and high-temperature stability of the reinforcing phase. Simultaneously, existing cladding materials exhibit poor matching between powder flowability and loose packing density, easily resulting in uneven powder feeding and high porosity during laser cladding, affecting coating quality. In conclusion, developing a nano-reinforced gradient composition cladding material for cutting tool alloy steel with good interfacial compatibility, a reasonable gradient distribution, stable high-temperature performance, and excellent forming quality has become an urgent need to overcome existing technological bottlenecks. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a cladding material for nano-reinforced gradient composition tool alloy steel.

[0005] (II) Technical Solution A cladding material for nano-reinforced gradient composition cutting tool alloy steel is composed of a base alloy powder, a composite nano-reinforcing phase, and a gradient control agent. The weight percentages of each component in the total mass of the cladding material are as follows: base alloy powder 70-85 parts, composite nano-reinforcing phase 8-15 parts, and gradient control agent 2-5 parts. The base alloy powder is an iron-based alloy powder, and the weight percentages of each component in the total mass of the base alloy powder are: Cr 12%-18%, Ni 5%-10%, Ti 3%-6%, B 0.8%-1.5%, Nb 0.5%-1.2%, with the balance being iron; the composite nano-reinforcing phase is an in-situ self-generated TiC and nano-CBN crystal plane matching composite system, with an average TiC particle size of 20-60 nm and an average CBN particle size of 15-40 nm, and a weight ratio of 3:1-5:1; the gradient regulation aid is a functional synergistic mixture of La2O3 and Y2O3, with the two accounting for 60-70% and 30-40% of the total mass of the gradient regulation aid by weight, respectively.

[0006] Preferably, the base alloy powder has a bimodal particle size distribution, wherein the 40-50μm coarse powder accounts for 60% of the total mass of the base alloy powder by weight, the 10-20μm fine powder accounts for 40% of the total mass of the base alloy powder by weight, the powder purity is ≥99.8%, and the powder sphericity is ≥0.92.

[0007] Preferably, the in-situ self-generated TiC is produced by laser cladding of Ti powder and graphite powder at an energy density of 150-200 J / mm². 2 Under certain conditions, an in-situ reaction is triggered to generate Ti powder and graphite powder in a weight ratio of 5:1. The TiC particles generated by the reaction are dispersedly distributed within the grains and grain boundaries of the alloy matrix.

[0008] Preferably, nano-SiC is also added to the composite nano-reinforcing phase. The average particle size of the nano-SiC is 30-40 nm, and it is added only in the 0-1.0 mm wear-resistant section of the coating surface, forming a dual nano-hard phase synergistic reinforcement structure with CBN.

[0009] Preferably, the gradient regulation agent further includes CeO2, which forms a rare earth oxide composite system with La2O3 and Y2O3.

[0010] Preferably, the cladding material is distributed in a segmented gradient along the coating thickness direction. The weight percentage of the composite nano-reinforcing phase in the bottom 0.5-1.0mm bonding section of the coating gradually increases to 8% at a rate of 0.5% / 100μm. The weight percentage in the middle 1.0-2.0mm transition section of the coating steadily increases to 15% at a rate of 1.0% / 100μm. The weight percentage in the surface 0-1.0mm wear-resistant section of the coating increases sharply to a high value of 18%-22% at a rate of 3.0% / 100μm. The weight percentage of the gradient control additive is uniformly distributed throughout the entire coating thickness direction.

[0011] Preferably, the preparation method of the cladding material for nano-reinforced gradient composition tool alloy steel includes the following steps: S1: Weigh each component of the base alloy powder according to the weight percentage, put them into a planetary ball mill, use argon as the protective gas, use zirconia ceramic balls as the grinding media, and the ball-to-material ratio is 10:1-15:1. First, ball mill at high speed of 350-450 r / min for 5-8 hours, and then ball mill at low speed of 150-200 r / min for 10-17 hours to obtain a uniformly mixed base alloy powder. S2: Weigh Ti powder, graphite powder and nano CBN, add gradient control agent, and continue ball milling at 250-300 r / min for 8-12 h. During the ball milling process, control the temperature inside the mill cavity to ≤50℃ to form a premixed powder. S3: Place the premixed powder into a laser selective gradient coating equipment, and design it according to the segmented gradient design of the bottom bonding section, the middle transition section and the surface wear-resistant section. Control the thickness of each layer of coating to 50-100μm. Keep it at a pressure of 50-80MPa and a temperature of 80-120℃ for 2-4 hours. After cooling to room temperature, crush it and pass it through a 200-300 mesh sieve to obtain the cladding material.

[0012] Preferably, stearic acid is added as a dispersant after the high-speed ball milling stage in S1. The ball milling media adopts a large ball to small ball weight ratio of 2:1, with the large ball diameter being 10 mm and the small ball diameter being 5 mm.

[0013] Preferably, the laser selective gradient fabrication process in S3 consists of three layers, corresponding to the cutting edge wear-resistant layer, the cutting body transition layer, and the substrate bonding layer of the cutting tool. The weight percentage difference of the composite nano-reinforcing phase in the cutting edge wear-resistant layer is 5%, the weight percentage difference in the cutting body transition layer is 3%, and the weight percentage difference in the substrate bonding layer is 0.5%. Furthermore, an inert gas atmosphere is used for protection during the fabrication process.

[0014] Preferably, the process also includes step S4: placing the sieved cladding material into a vacuum drying oven and keeping it at a temperature of 100-120℃ and a vacuum degree of ≤10Pa for 3-5 hours; then introducing an argon-hydrogen mixed passivation gas with a volume ratio of argon to hydrogen of 95:5 and passivating at room temperature for 1-2 hours to form a passivation film.

[0015] (iii) Beneficial technical effects Compared with existing technologies, the beneficial effects of this invention are: 1. The composite nano-reinforcing phase employs a crystal plane-matched compounding system, significantly improving the interfacial compatibility between the reinforcing phase and the matrix, avoiding the problems of reinforcing phase agglomeration and segregation, resulting in a uniform and dense internal structure of the coating and significantly enhancing the overall mechanical properties of the coating. Secondly, the cladding material adopts a segmented gradient distribution design. The gentle gradient distribution at the bottom of the coating ensures a strong bond with the tool alloy steel matrix, effectively reducing the risk of coating peeling; the stable gradient distribution in the middle gives the coating excellent impact resistance; and the steeply increasing gradient distribution on the surface maximizes the coating's wear resistance, comprehensively matching the complex service conditions of the tool.

[0016] 2. The gradient regulation additive adopts a rare earth oxide composite system, which realizes the synergistic effect of functions. It can not only induce the in-situ generation of the reinforcing phase, but also inhibit the high-temperature decomposition of the reinforcing phase, significantly improving the high-temperature stability of the coating, so that the coating can still maintain good mechanical properties under high-temperature conditions.

[0017] 3. Composite rare earth additives can further refine the coating grains, improve the corrosion resistance of the coating, and expand the application scenarios of cladding tools. By using segmented ball milling and laser selective gradient feeding processes, the powder properties of the cladding material are optimized, the powder flowability and loose density matching are improved, the powder feeding uniformity during laser cladding is ensured, the coating porosity is reduced, and the coating forming quality is improved. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for preparing a cladding material for nano-reinforced gradient composition tool alloy steel, as disclosed in this invention. Figure 2 This is a line graph comparing the surface hardness of the coating and the bonding strength between the coating and the substrate in the examples and comparative examples; Figure 3 This is a graph comparing the impact resistance and coating porosity of the embodiments and comparative examples using a histogram. Figure 4 This is a radar comparison chart created by standardizing the dimensions of the performance comparison data of the examples and comparative examples. Detailed Implementation

[0019] according to Figures 1 to 4 The specific embodiments of the present invention are as follows: The following detailed description, in conjunction with embodiments and comparative examples, illustrates the nano-reinforced gradient composition tool alloy steel cladding material and its preparation method of the present invention. All raw materials used in the embodiments and comparative examples are of industrial grade purity and, unless otherwise specified, have been purified using conventional processes.

[0020] I. Example 1 (a) Component Design The base alloy powder consists of 77 parts, which are iron-based alloy powders with a bimodal particle size distribution design. 60% of the powder is coarse (40-50 μm), and 40% is fine (10-20 μm). The powder purity is 99.8%, and the sphericity is 0.92. Its chemical composition, based on the total mass percentage of the base alloy powder, is: Cr 15%, Ni 7%, Ti 4.5%, B 1.1%, Nb 0.8%, with the balance being iron.

[0021] Eleven composite nano-reinforcing phases were used, consisting of an in-situ self-generated TiC and nano-CBN crystal plane-matched composite system with a weight ratio of 4:1. The average particle size of TiC was 40 nm, and the average particle size of nano-CBN was 25 nm. The in-situ self-generated TiC was produced by laser cladding of Ti powder and graphite powder at an energy density of 175 J / mm². 2 Under certain conditions, an in-situ reaction is triggered to generate TiC particles, with a Ti powder to graphite powder weight ratio of 5:1. The generated TiC particles are dispersed within the grains and grain boundaries of the alloy matrix. Simultaneously, nano-SiC with an average particle size of 35 nm is added to the composite nano-reinforcing phase. This nano-SiC is added only to the 0-1.0 mm wear-resistant section of the coating surface, forming a synergistic reinforcement structure with CBN through a dual nano-hard phase.

[0022] Three parts of gradient regulation additives were used, which were rare earth oxide composite systems formed by La2O3, Y2O3 and CeO2. The total mass ratio of the gradient regulation additives was: La2O3 65%, Y2O3 30%, CeO2 5%.

[0023] The cladding material exhibits a segmented gradient distribution along the coating thickness, with a total coating thickness of 1.5 mm. Within the bottom 0.7 mm bonding section, the weight percentage of the composite nano-reinforcing phase gradually increases to 8% at a rate of 0.5% / 100 μm; within the middle 0.8 mm transition section, the weight percentage steadily increases to 15% at a rate of 1.0% / 100 μm; and within the surface 0-1.0 mm wear-resistant section, the weight percentage sharply increases to a high value of 20% at a rate of 3.0% / 100 μm. The weight percentage of the gradient-regulating additive is uniformly distributed throughout the entire coating thickness.

[0024] (II) Preparation steps S1: Weigh each component of the base alloy powder according to the above chemical composition, mix them, and transfer them to a planetary ball mill. Use argon as the protective gas at a flow rate of 5 L / min. The milling media are zirconia ceramic balls with a large ball diameter of 10 mm and a small ball diameter of 5 mm. The weight ratio of large balls to small balls is 2:1, and the total ball-to-material ratio is 12:1. First, ball mill at a high speed of 400 r / min for 6 hours. After the high-speed ball milling stage, add stearic acid as a dispersant, and then ball mill at a low speed of 180 r / min for 14 hours to obtain a uniformly mixed base alloy powder.

[0025] S2: Weigh Ti powder, graphite powder, and nano-CBN according to the above chemical composition, add gradient control additives, and transfer them together into the planetary ball mill. Ball mill at 280 r / min for 10 h. During the ball milling process, the temperature inside the chamber is controlled to not exceed 50℃ by circulating cooling water through the mill jacket to avoid oxidation and agglomeration of nanoparticles and to form a premixed powder.

[0026] S3: The premixed powder is transferred to a laser selective gradient cladding device, which consists of three cladding units corresponding to the substrate bonding layer, the blade transition layer, and the cutting edge wear-resistant layer of the cutting tool, respectively. The cladding is performed according to a segmented gradient design, with each layer being 80 μm thick. Argon gas is introduced during the cladding process as an inert protective gas at a flow rate of 3 L / min to prevent powder oxidation. After cladding, the powder is held at 60 MPa and 100°C for 3 hours to achieve initial densification. After natural cooling to room temperature, the blocky powder is crushed and screened through a 250-mesh standard sieve to remove large particle agglomerates, obtaining a gradient-distributed cladding material crude product. The weight percentage difference of the composite nano-reinforcing phase in the cutting edge wear-resistant layer is 5%, the weight percentage difference in the blade transition layer is 3%, and the weight percentage difference in the substrate bonding layer is 0.5%.

[0027] S4: Place the sieved cladding material crude product into a vacuum drying oven, set the temperature to 110℃ and the vacuum degree to 8Pa, and keep it at this temperature for 4 hours to remove the moisture and residual gas adsorbed by the powder. After drying, introduce an argon-hydrogen mixed passivation gas into the oven, with an argon to hydrogen volume ratio of 95:5, and passivate at room temperature for 1.5 hours to form a dense passivation film on the powder surface, improving storage stability and finally obtaining the finished cladding material.

[0028] II. Example 2 (a) Component Design The base alloy powder consists of 70 parts, which is an iron-based alloy powder with a bimodal particle size distribution design. 60% of the powder is coarse (40-50 μm), and 40% is fine (10-20 μm). The powder purity is 99.9%, and the sphericity is 0.93. Its chemical composition, based on the total mass percentage of the base alloy powder, is: Cr 12%, Ni 5%, Ti 3%, B 0.8%, Nb 0.5%, with the balance being iron.

[0029] Eight parts of the composite nano-reinforcing phase consist of an in-situ self-generated TiC and nano-CBN crystal plane-matched composite system, with a weight ratio of 3:1. The average particle size of TiC is 20 nm, and the average particle size of nano-CBN is 15 nm. The in-situ self-generated TiC is generated by an in-situ reaction triggered by Ti powder and graphite powder under laser cladding energy density of 150 J / mm², with a Ti powder to graphite powder weight ratio of 5:1. The generated TiC particles are dispersedly distributed within the grains and grain boundaries of the alloy matrix. Simultaneously, nano-SiC with an average particle size of 30 nm is added to the composite nano-reinforcing phase, added only in the 0-1.0 mm wear-resistant section of the coating surface, forming a synergistic reinforcement structure with CBN using a dual nano-hard phase.

[0030] Two parts of gradient regulation additives were used, which were rare earth oxide composite systems formed by La2O3, Y2O3 and CeO2. The total mass ratio of the gradient regulation additives was: 60% La2O3, 35% Y2O3 and 5% CeO2.

[0031] The cladding material exhibits a segmented gradient distribution along the coating thickness direction, with a total coating thickness of 1.0 mm. Within the bottom 0.5 mm bonding section, the weight percentage of the composite nano-reinforcing phase gradually increases to 8% at a rate of 0.5% / 100 μm; within the middle 0.5 mm transition section, the weight percentage steadily increases to 15% at a rate of 1.0% / 100 μm; and within the surface 0-1.0 mm wear-resistant section, the weight percentage sharply increases to a high value of 18% at a rate of 3.0% / 100 μm. The weight percentage of the gradient-regulating additive is uniformly distributed throughout the entire coating thickness direction.

[0032] (II) Preparation steps S1: Weigh each component of the base alloy powder according to the above chemical composition, mix them, and transfer them to a planetary ball mill. Use argon as the protective gas at a flow rate of 4 L / min. The milling media are zirconia ceramic balls with a large ball diameter of 10 mm and a small ball diameter of 5 mm. The weight ratio of large balls to small balls is 2:1, and the total ball-to-material ratio is 10:1. First, ball mill at a high speed of 350 r / min for 5 hours. After the high-speed ball milling stage, add stearic acid as a dispersant, and then ball mill at a low speed of 200 r / min for 10 hours to obtain a uniformly mixed base alloy powder.

[0033] S2: Weigh Ti powder, graphite powder, and nano-CBN according to the above chemical composition, add gradient control additives, and transfer them together into the planetary ball mill. Ball mill at 250 r / min for 8 hours. During the ball milling process, the temperature inside the chamber is controlled to not exceed 48℃ by circulating cooling water through the mill jacket to avoid oxidation and agglomeration of nanoparticles and to form a premixed powder.

[0034] S3: The premixed powder is transferred to a laser selective gradient cladding device, which consists of three cladding units corresponding to the substrate bonding layer, the blade transition layer, and the cutting edge wear-resistant layer of the cutting tool. The cladding is performed according to a segmented gradient design, with each layer being 50 μm thick. Nitrogen gas is introduced during the cladding process as an inert protective gas at a flow rate of 2 L / min to prevent powder oxidation. After cladding, the powder is held at 50 MPa and 80°C for 2 hours to achieve initial densification. After natural cooling to room temperature, the blocky powder is crushed and screened through a 200-mesh standard sieve to remove large agglomerates, obtaining a gradient-distributed cladding material crude product. The weight percentage difference of the composite nano-reinforcing phase in the cutting edge wear-resistant layer is 5%, the weight percentage difference in the blade transition layer is 3%, and the weight percentage difference in the substrate bonding layer is 0.5%.

[0035] S4: Place the sieved crude cladding material into a vacuum drying oven, set the temperature to 100℃ and the vacuum degree to 5Pa, and keep it at this temperature for 3 hours to remove the moisture and residual gas adsorbed by the powder. After drying, introduce an argon-hydrogen mixed passivation gas into the oven, with an argon to hydrogen volume ratio of 95:5, and passivate at room temperature for 1 hour to form a dense passivation film on the powder surface, improving storage stability and finally obtaining the finished cladding material.

[0036] III. Example 3 (a) Component Design The base alloy powder consists of 85 parts, which is an iron-based alloy powder with a bimodal particle size distribution design. 60% of the powder is 40-50 μm coarse powder, and 40% is 10-20 μm fine powder. The powder purity is 99.9%, and the sphericity is 0.95. Its chemical composition, based on the total mass percentage of the base alloy powder, is: Cr 18%, Ni 10%, Ti 6%, B 1.5%, Nb 1.2%, with the balance being iron.

[0037] Fifteen parts of the composite nano-reinforcing phase consist of an in-situ self-generated TiC and nano-CBN crystal plane-matched composite system, with a weight ratio of 5:1. The average particle size of TiC is 60 nm, and the average particle size of nano-CBN is 40 nm. The in-situ self-generated TiC is generated by an in-situ reaction triggered by Ti powder and graphite powder under laser cladding energy density of 200 J / mm², with a Ti powder to graphite powder weight ratio of 5:1. The generated TiC particles are dispersedly distributed within the grains and grain boundaries of the alloy matrix. Simultaneously, nano-SiC with an average particle size of 40 nm is added to the composite nano-reinforcing phase, added only in the 0-1.0 mm wear-resistant section of the coating surface, forming a synergistic reinforcement structure with CBN using a dual nano-hard phase.

[0038] Five parts of gradient regulation additives were used, which were rare earth oxide composite systems formed by La2O3, Y2O3 and CeO2. The total mass ratio of the gradient regulation additives was: 70% La2O3, 25% Y2O3 and 5% CeO2.

[0039] The cladding material exhibits a segmented gradient distribution along the coating thickness, with a total coating thickness of 2.0 mm. Within the bottom 1.0 mm bonding section, the weight percentage of the composite nano-reinforcing phase gradually increases to 8% at a rate of 0.5% / 100 μm; within the middle 1.0 mm transition section, the weight percentage steadily increases to 15% at a rate of 1.0% / 100 μm; and within the 0-1.0 mm wear-resistant section on the surface of the coating, the weight percentage sharply increases to a high value of 22% at a rate of 3.0% / 100 μm. The weight percentage of the gradient-regulating additive is uniformly distributed throughout the entire coating thickness.

[0040] (II) Preparation steps S1: Weigh each component of the base alloy powder according to the above chemical composition, mix them, and transfer them to a planetary ball mill. Use argon as the protective gas at a flow rate of 6 L / min. The milling media are zirconia ceramic balls with a large ball diameter of 10 mm and a small ball diameter of 5 mm. The weight ratio of large balls to small balls is 2:1, and the total ball-to-material ratio is 15:1. First, ball mill at a high speed of 450 r / min for 8 hours. After the high-speed ball milling stage, add stearic acid as a dispersant, and then ball mill at a low speed of 150 r / min for 17 hours to obtain a uniformly mixed base alloy powder.

[0041] S2: Weigh Ti powder, graphite powder, and nano-CBN according to the above chemical composition, add gradient control additives, and transfer them together into the planetary ball mill. Ball mill at 300 r / min for 12 h. During the ball milling process, the temperature inside the chamber is controlled to not exceed 45℃ by circulating cooling water through the mill jacket to avoid oxidation and agglomeration of nanoparticles and form a premixed powder.

[0042] S3: The premixed powder is transferred to a laser selective gradient cladding device, which consists of three cladding units corresponding to the substrate bonding layer, the blade transition layer, and the cutting edge wear-resistant layer of the cutting tool, respectively. The cladding is performed according to a segmented gradient design, with each layer being 100μm thick. Argon gas is introduced during the cladding process as an inert protective gas at a flow rate of 4L / min to prevent powder oxidation. After cladding, the powder is held at 80MPa and 120℃ for 4 hours to achieve initial densification. After natural cooling to room temperature, the blocky powder is crushed and screened through a 300-mesh standard sieve to remove large particle agglomerates, obtaining a gradient-distributed cladding material crude product. The weight percentage difference of the composite nano-reinforcing phase in the cutting edge wear-resistant layer is 5%, the weight percentage difference in the blade transition layer is 3%, and the weight percentage difference in the substrate bonding layer is 0.5%.

[0043] S4: Place the sieved cladding material crude product into a vacuum drying oven, set the temperature to 120℃ and the vacuum degree to 10Pa, and keep it at this temperature for 5 hours to remove the moisture and residual gas adsorbed by the powder. After drying, introduce an argon-hydrogen mixed passivation gas into the oven, with an argon to hydrogen volume ratio of 95:5, and passivate at room temperature for 2 hours to form a dense passivation film on the powder surface, improving storage stability and finally obtaining the finished cladding material.

[0044] IV. Comparative Example 1 (a) Component Design The base alloy powder consists of 80 parts, which is an iron-based alloy powder with a unimodal particle size distribution design. 100% of the powder is 30-40 μm, with a purity of 99.7% and a sphericity of 0.90. Its chemical composition, based on the total mass percentage of the base alloy powder, is: Cr 14%, Ni 8%, Ti 2%, B 0.6%, Nb 0.4%, with the balance being iron.

[0045] Ten parts of the reinforcing phase were a mixed system of externally doped TiC and nano-CBN, with a weight ratio of 4:1. The average particle size of TiC was 50 nm, and the average particle size of nano-CBN was 30 nm. No in-situ self-generation process was used, and no nano-SiC was added.

[0046] Three parts of the additive, consisting of a single La2O3 with a purity of 99.8% and a particle size ≤5μm.

[0047] The cladding material is linearly gradient distributed along the coating thickness direction. The total coating thickness is 1.5 mm. The weight percentage of the reinforcing phase increases linearly from 6% to 14%, and the weight percentage of the additives is uniformly distributed throughout the coating thickness direction.

[0048] (II) Preparation steps Weigh each component of the base alloy powder according to the above chemical composition, add external dopant TiC, nano CBN and La2O3 additives, mix and transfer to a planetary ball mill.

[0049] Using air as the medium and without inert gas protection, the ball milling media is zirconia ceramic balls with a ball-to-material ratio of 12:1. It is continuously ball-milled at a single speed of 300 r / min for 15 hours without the addition of stearic acid dispersant. During the ball milling process, the temperature inside the chamber naturally rises to about 60℃.

[0050] The mixed powder is transferred to a standard fabric-laying machine and fabricated according to a linear gradient design, with each layer 80 μm thick. The powder is then held at 60 MPa and 100°C for 3 hours to densify it. After natural cooling to room temperature, the lumpy powder is crushed and screened through a 250-mesh standard sieve to obtain the crude cladding material.

[0051] The sieved cladding material was placed in a regular drying oven, the temperature was set to 110℃, and it was kept at that temperature for 4 hours to remove the moisture adsorbed by the powder. No passivation treatment was performed, and the finished cladding material was obtained directly.

[0052] The basic mechanics and coating formation of the examples and comparative examples are compared in the table below: Table 1

[0053] The specific performance comparisons between the examples and comparative examples are shown in the table below: Table 2

[0054] Based on the performance data in both tables, it can be seen that the cladding materials prepared in Examples 1-3 of this invention exhibit significant advantages in basic mechanical properties, coating forming quality, and specific application performance, with overall performance superior to Comparative Example 1. Example 3, with its higher content of composite nano-reinforcing phase, optimized process parameters, and complete core technology solution, demonstrates the best performance in key indicators such as hardness, bonding strength, wear resistance, and high-temperature stability. Although the performance of Example 2 is slightly lower than that of Example 1, it still far exceeds that of Comparative Example 1, meeting the requirements for cladding of tool alloy steel and reflecting the rationality of the gradient design of composition and process parameters. Comparative Example 1, lacking the core technologies of this invention such as in-situ self-generated reinforcing phase, segmented gradient distribution, and rare earth composite additives, exhibits significant shortcomings in interface bonding, density, high-temperature stability, and long-term storage, further confirming the performance-enhancing effect of the technical solution of this invention on the cladding material.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cladding material for nano-reinforced gradient composition tool alloy steel, characterized in that, The cladding material is composed of a basic alloy powder, a composite nano-reinforcing phase, and a gradient regulation agent. The weight percentages of each component in the total mass of the cladding material are as follows: basic alloy powder 70-85 parts, composite nano-reinforcing phase 8-15 parts, and gradient regulation agent 2-5 parts. The basic alloy powder is an iron-based alloy powder, and the weight percentages of each component in the total mass of the basic alloy powder are: Cr 12%-18%, Ni 5%-10%, Ti 3%-6%, B 0.8%-1.5%, Nb 0.5%-1.2%, with the balance being iron. The composite nano-reinforcing phase is an in-situ self-generated TiC and nano-CBN crystal plane-matched composite system, with an average TiC particle size of 20-60 nm and an average CBN particle size of 15-40 nm, in a weight ratio of 3:1-5:

1. The gradient regulation agent is a functionally synergistic mixture of La2O3 and Y2O3, with the weight percentages of La2O3 being 60-70% and Y2O3 being 30-40% of the total mass of the gradient regulation agent.

2. The cladding material for nano-reinforced gradient composition tool alloy steel according to claim 1, characterized in that, The base alloy powder has a bimodal particle size distribution, wherein 40-50μm coarse powder accounts for 60% of the total mass of the base alloy powder by weight, and 10-20μm fine powder accounts for 40% of the total mass of the base alloy powder by weight. The powder purity is ≥99.8%, and the powder sphericity is ≥0.

92.

3. The cladding material for nano-reinforced gradient composition tool alloy steel according to claim 1, characterized in that, The in-situ generated TiC is produced by laser cladding of Ti powder and graphite powder at an energy density of 150-200 J / mm². 2 Under certain conditions, an in-situ reaction is triggered to generate Ti powder and graphite powder in a weight ratio of 5:

1. The TiC particles generated by the reaction are dispersedly distributed within the grains and grain boundaries of the alloy matrix.

4. The cladding material for nano-reinforced gradient composition tool alloy steel according to claim 1, characterized in that, The composite nano-reinforcing phase also contains nano-SiC with an average particle size of 30-40 nm, and it is added only in the 0-1.0 mm wear-resistant section of the coating surface, forming a dual nano-hard phase synergistic reinforcement structure with CBN.

5. The cladding material for nano-reinforced gradient composition tool alloy steel according to claim 1, characterized in that, The gradient regulation agent also includes CeO2, which forms a rare earth oxide composite system with La2O3 and Y2O3.

6. The cladding material for nano-reinforced gradient composition tool alloy steel according to claim 1, characterized in that, The cladding material is distributed in a segmented gradient along the coating thickness direction. The weight percentage of the composite nano-reinforcing phase in the bottom 0.5-1.0 mm bonding section of the coating gradually increases to 8% at a rate of 0.5% / 100μm. The weight percentage in the middle 1.0-2.0 mm transition section of the coating steadily increases to 15% at a rate of 1.0% / 100μm. The weight percentage in the surface 0-1.0 mm wear-resistant section of the coating increases sharply to a high value of 18%-22% at a rate of 3.0% / 100μm. The weight percentage of the gradient control additive is uniformly distributed throughout the entire coating thickness direction.

7. A method for preparing a cladding material for nano-reinforced gradient composition tool alloy steel according to any one of claims 1, characterized in that, Includes the following steps: S1: Weigh each component of the base alloy powder according to the weight percentage, put them into a planetary ball mill, use argon as the protective gas, use zirconia ceramic balls as the grinding media, and the ball-to-material ratio is 10:1-15:

1. First, ball mill at high speed of 350-450 r / min for 5-8 hours, and then ball mill at low speed of 150-200 r / min for 10-17 hours to obtain a uniformly mixed base alloy powder. S2: Weigh Ti powder, graphite powder and nano CBN, add gradient control agent, and continue ball milling at 250-300 r / min for 8-12 h. During the ball milling process, control the temperature inside the mill cavity to ≤50℃ to form a premixed powder. S3: Place the premixed powder into a laser selective gradient coating equipment, and design it according to the segmented gradient design of the bottom bonding section, the middle transition section and the surface wear-resistant section. Control the thickness of each layer of coating to 50-100μm. Keep it at a pressure of 50-80MPa and a temperature of 80-120℃ for 2-4 hours. After cooling to room temperature, crush it and pass it through a 200-300 mesh sieve to obtain the cladding material.

8. The method for preparing the cladding material for nano-reinforced gradient composition tool alloy steel according to claim 7, characterized in that, Stearic acid was added as a dispersant after the high-speed ball milling stage in S1. The ball milling media adopted a ratio of large balls to small balls of 2:1 by weight, with large balls having a diameter of 10 mm and small balls having a diameter of 5 mm.

9. The method for preparing the cladding material for nano-reinforced gradient composition tool alloy steel according to claim 7, characterized in that, The laser selective gradient fabrication process in S3 consists of three layers, corresponding to the cutting edge wear-resistant layer, the cutting body transition layer, and the substrate bonding layer. The weight percentage difference of the composite nano-reinforcing phase in the cutting edge wear-resistant layer is 5%, the weight percentage difference in the cutting body transition layer is 3%, and the weight percentage difference in the substrate bonding layer is 0.5%. Furthermore, an inert gas atmosphere is used for protection during the fabrication process.

10. The method for preparing the cladding material for nano-reinforced gradient composition tool alloy steel according to claim 7, characterized in that, It also includes S4: placing the sieved cladding material into a vacuum drying oven and keeping it at a temperature of 100-120℃ and a vacuum degree of ≤10Pa for 3-5 hours; then introducing an argon-hydrogen mixed passivation gas with a volume ratio of argon to hydrogen of 95:5, and passivating it at room temperature for 1-2 hours to form a passivation film.

Images