Surface treatment composite process for prolonging service life of stamping die

Abstract

The invention belongs to the technical field of die machining, and discloses a surface treatment composite process for prolonging the service life of a stamping die, which comprises the following steps: S1, matrix pretreatment; s2, preparing a gradient permeation and diffusion layer; s3, performing strong beam deposition on the composite coating; s4, carrying out a post-treatment process; the substrate pretreatment comprises vacuum subzero treatment and surface nano shot peening strengthening, and the gradient permeation and diffusion layer preparation comprises double-layer glow plasma metal permeation and low-temperature active screen plasma nitriding. According to the method, stress peak points are dispersed through element affinity, a nano layered transition structure and a superlattice functional layer in strong beam deposition form multi-stage synergy, interface shear energy is released while ultrahigh pressure stress is maintained through alternately stacked hard phases, finally, stress field distribution is reconstructed through ion beam induced diffusion and sub-temperature relaxation, and the super-high-pressure ultrahigh-pressure stress is obtained. The whole set of technology enables the die to form a self-adaptive buffer system with gradually-decreased stress from a substrate to a plating layer, and the problem that microcracks induced by stress concentration rapidly expand along an interface is thoroughly solved.

Description

Technical Field

[0001] This invention belongs to the field of mold processing technology, specifically a surface treatment composite process for improving the life of stamping dies. Background Technology

[0002] Composite surface treatment technology for stamping dies is an advanced process that combines multiple surface treatment techniques to improve the wear resistance, corrosion resistance, and service life of the dies. Common composite processes include surface carburizing, nitriding, and coating treatments. These methods can effectively improve the hardness, fatigue resistance, and oxidation resistance of the die surface. Carburizing or nitriding treatments can form a high-hardness thin layer on the die surface, effectively resisting the wear and corrosion generated during stamping, while coating treatments can form a protective film on the die surface, further enhancing its corrosion resistance and oxidation resistance.

[0003] However, traditional composite surface treatment processes for stamping dies mainly suffer from residual stress mismatch and thermal history differences between the same process layers, which induce early fatigue failure. When physical vapor deposition is used, although the deposition temperature of 200-500℃ can preserve the hardness of the substrate, the high-energy particles bombarding the deposition process form intrinsic tensile stress (often reaching 1-5GPa) inside the coating. When superimposed on the die substrate that has undergone quenching / tempering pretreatment (compressive stress layer), shear stress concentration occurs at the interface. Especially at stress concentration areas such as the cutting edge, microcracks are prone to initiation under alternating stamping loads and propagate along the coating / substrate interface.

[0004] When using a composite process of plasma nitriding and PVD, the nitriding layer (approximately 500-580℃) causes secondary tempering of the substrate, reducing the surface hardness by 3-5 HRC. The subsequent low-temperature deposition of PVD cannot compensate for this softening. The stress field synergistic failure leads to a decrease in the substrate's support strength, and the coating peels off in large areas after millions of strokes. At the same time, the composite process requires multiple entries and exits from the processing equipment, and repeated heating and cooling cause the substrate to undergo uncontrolled thermal cycling. Repeated cycling of high-speed steel in the 300-500℃ range will promote carbide coarsening and precipitation of brittle η phase at grain boundaries. The longer the process chain, the more significant the accumulation of microscopic damage to the substrate, directly weakening the overall fatigue life of the mold. Summary of the Invention

[0005] The purpose of this invention is to provide a surface treatment composite process for improving the life of stamping dies, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a surface treatment composite process for improving the life of stamping dies, comprising the following steps:

[0007] S1: Matrix pretreatment;

[0008] S2: Preparation of gradient diffusion layer;

[0009] S3: High-current deposition composite coating;

[0010] S4: Post-processing;

[0011] The substrate pretreatment includes vacuum cryogenic treatment and surface nano-shot peening. The gradient diffusion layer preparation includes double-layer glow discharge plasma metallization and low-temperature active screen plasma nitriding. The high-current deposition composite coating includes magnetron sputtering transition layer deposition and high-power pulsed magnetron sputtering functional layer. The post-treatment process includes low-temperature ion beam mixing treatment and vacuum relaxation annealing.

[0012] As a further technical solution of the present invention, the vacuum cryogenic treatment includes using SKD11 high-carbon high-chromium steel mold material, whose chemical composition is 1.5% carbon, 12.0% chromium, 0.8% molybdenum, and 0.35% vanadium. First, it is oil quenched at 1020 degrees Celsius and held for 30 minutes. Then, it is deeply cooled to -110 degrees Celsius in a liquid nitrogen environment for 90 minutes. After that, a stepped tempering process is implemented: the temperature is increased to +150 degrees Celsius at a rate of 5 degrees Celsius per minute and held for 120 minutes. Then, the temperature is increased to +520 degrees Celsius at a rate of 3 degrees Celsius per minute and held for 180 minutes. Finally, a second stage of deep cooling is performed using a dry ice ethanol bath to -80 degrees Celsius and held for 120 minutes.

[0013] As a further technical solution of the present invention, the surface nano-shot peening includes using zirconia ceramic pellets with a diameter of 50 micrometers as the shot peening medium to achieve 300% coverage impact treatment under a spraying pressure of 0.35 MPa, forming a nano-scale surface layer with a thickness of 20 micrometers, a grain size of no more than 50 nanometers, and a surface compressive stress value of -850 MPa.

[0014] As a further technical solution of the present invention, the double-layer glow discharge plasma metallization includes configuring a 99.99% pure chromium target and a 99.95% pure tungsten target as source electrodes, applying a 750V glow discharge voltage for 180 minutes under the conditions of a substrate temperature of 480 degrees Celsius and a working pressure of 35 Pa, to form a 15-micrometer thick Cr / W gradient layer, with the chromium concentration gradually changing from 28% on the surface to 5% on the bottom layer, and the tungsten concentration decreasing from 15% to 8%.

[0015] As a further technical solution of the present invention, the low-temperature active screen plasma nitriding includes using a mixed gas with a nitrogen-hydrogen volume ratio of 3:1, and controlling the substrate temperature at 380 degrees Celsius for 240 minutes under a working pressure of 280 Pa and a pulse frequency of 15 kHz to generate a 5-micron thick compound layer, wherein the ε-Fe2-3N phase content is not less than 95% and the surface hardness reaches 1350HV0.05.

[0016] As a further technical solution of the present invention, the magnetron sputtering transition layer deposition includes using a titanium 80 aluminum 20 alloy target, applying a negative 100 volt substrate bias and 8 kW sputtering power under an argon flow rate of 150 standard milliliters per minute, maintaining a deposition temperature of 180 degrees Celsius, and depositing a 0.8 micrometer thick nanolayered TiAlN structure at a rate of 3 nanometers per minute, with the interlayer spacing precisely controlled at 10 nanometers.

[0017] As a further technical solution of the present invention, the high-power pulsed magnetron sputtering functional layer includes using an aluminum 70Cr30 alloy target, configured with a pulse peak power of 2500 kW, a pulse width of 50 microseconds and a frequency of 500 Hz, and processed for 300 minutes under the conditions of negative 800 V pulse bias, 260 °C substrate temperature and 0.25 Pa deposition gas pressure to form a dual-structure functional layer: the bottom layer is a 3 μm thick AlCrN nanocrystalline layer with a grain size of 30 nm and a stoichiometric ratio of 1:1, and the surface layer is a 1.2 μm superlattice structure composed of AlCrN and AlCrON with a periodic alternation of 15 nm, with a final surface hardness of 3500 HV0.025 and a residual compressive stress of negative 2.1 GPa.

[0018] As a further technical solution of the present invention, the low-temperature ion beam mixing treatment includes using a Kaufman-type ion source, with a beam current energy of 800 electron volts and a beam current density of 150 microamps per square centimeter, and continuously introducing argon gas at a rate of 20 standard milliliters per minute for 40 minutes to form a 120-nanometer thick composition gradient transition layer at the coating interface.

[0019] As a further technical solution of the present invention, the vacuum relaxation annealing includes annealing at 280 degrees Celsius under a vacuum of 2 x 10 -3 Pa, holding at that temperature for 90 minutes, and then cooling in a stepwise manner from furnace cooling to 100 degrees Celsius and then air cooling, so that the residual stress on the coating surface is reduced to -1.5 GPa and the interfacial shear strength is increased by 40%.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) This invention fundamentally eliminates the problem of stress mismatch in traditional composite processes by deeply coordinating material phase change regulation and interface design. The multi-level deep cryogenic tempering combined with high-energy shot peening in the substrate pretreatment stage constructs a nanocrystalline reinforcement layer with gradient compression characteristics. This structure forms a stable dislocation network at the molecular scale, effectively blocking the microscopic damage caused by subsequent thermal cycling. The gradient diffusion layer constructs a continuous chromium-tungsten concentration gradient and a high-purity nitride layer on the subsurface. The element affinity disperses the stress peak point. The nanolayer transition structure and the superlattice functional layer in the strong beam deposition form a multi-level synergy. The alternating stacked hard phases release interfacial shear energy while maintaining ultra-high pressure stress. Finally, the stress field distribution is reconstructed through ion beam induced diffusion and sub-temperature relaxation. The whole technology enables the mold to form an adaptive buffer system with decreasing stress from the substrate to the coating, completely solving the problem of rapid propagation of microcracks along the interface induced by stress concentration.

[0022] (2) This invention breaks through the bottleneck of uncontrollable deterioration in traditional heat treatment process, and ensures that the core performance of the material does not decay by controlling the low temperature throughout the process. The plasma infiltration temperature is strictly limited below the critical point of carbide coarsening, and the gradient infiltration layer and the ultra-stable nitride layer are deposited simultaneously. The functional coating deposition adopts high-energy beam non-equilibrium synthesis technology to avoid the tensile stress accumulation caused by conventional PVD high-temperature particle bombardment. The ion beam mixing treatment completes the interface healing at the atomic scale, replacing the high-temperature exposure link in the traditional equipment conversion process. This temperature-controlled system throughout the process keeps the high-speed steel matrix in a stable microstructure, fundamentally eliminating the risk of tempering softening and brittle phase precipitation. At the same time, the chromium-tungsten dispersion in the gradient strengthening layer plays a thermal barrier effect, and the superlattice structure of the functional layer reduces the accumulation of frictional heat through periodic alumina phase passivation, so that the mold can maintain a dynamic balance between surface hardness and core toughness under continuous stamping conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall process of the present invention;

[0024] Figure 2 This is a schematic diagram of the matrix pretreatment process of the present invention;

[0025] Figure 3 This is a schematic diagram of the process for preparing the gradient diffusion layer of the present invention;

[0026] Figure 4 This is a schematic diagram of the process for depositing the composite coating using a high-current beam in this invention.

[0027] Figure 5 This is a schematic diagram of the post-processing technology of the present invention;

[0028] Figure 6 This is a data comparison chart of the present invention and the traditional process. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figures 1 to 6 As shown in the embodiment of the present invention, a surface treatment composite process for improving the life of stamping dies includes the following steps:

[0031] S1: Matrix pretreatment;

[0032] S2: Preparation of gradient diffusion layer;

[0033] S3: High-current deposition composite coating;

[0034] S4: Post-processing;

[0035] The substrate pretreatment includes vacuum cryogenic treatment and surface nano-shot peening. The gradient diffusion layer preparation includes double-layer glow discharge plasma metallization and low-temperature active screen plasma nitriding. The high beam deposition composite coating includes magnetron sputtering transition layer deposition and high-power pulsed magnetron sputtering functional layer. The post-treatment process includes low-temperature ion beam mixing treatment and vacuum relaxation annealing.

[0036] By reconstructing gradient stress and coupling with multi-scale structures, a strong and tough synergistic system with high bonding strength is established. Specifically, this manifests as the formation of a continuously transitioning compressive stress field between the substrate and the coating, achieving cross-scale synergistic strengthening of the outer hardness and inner toughness, effectively suppressing interface failure and microcrack propagation under alternating loads.

[0037] like Figure 2 As shown, the vacuum cryogenic treatment involves using SKD11 high-carbon, high-chromium steel mold material, with a chemical composition of 1.5% carbon, 12.0% chromium, 0.8% molybdenum, and 0.35% vanadium. First, it undergoes oil quenching at 1020 degrees Celsius and holds for 30 minutes. Then, it undergoes a first-stage deep cooling process in a liquid nitrogen environment to -110 degrees Celsius and holds for 90 minutes. Following this, a stepped tempering process is implemented: heating at 5 degrees Celsius per minute to +150 degrees Celsius and holding for 120 minutes, then heating at 3 degrees Celsius per minute to +520 degrees Celsius and holding for 180 minutes. Finally, a second-stage deep cooling process is performed using a dry ice ethanol bath to -80 degrees Celsius and hold for 120 minutes. Surface nano-blasting strengthening involves using 50-micron diameter zirconia ceramic pellets as the blasting medium, achieving 300% coverage impact treatment under a blasting pressure of 0.35 MPa, forming a 20-micron thick nano-scale surface layer with a grain size no larger than 50 nanometers and a surface compressive stress value reaching -850 MPa.

[0038] Through the synergistic effect of cryogenic phase transformation and high-energy impact, a nanocrystalline reinforcement layer with extremely high pressure stress is constructed on the surface of the mold matrix. Specifically, this manifests as a deep transformation of retained austenite, promoting the dispersed distribution of ultrafine carbides, and simultaneously inducing grain nanostructuring through plastic deformation, forming a prestressed barrier that inhibits crack initiation, significantly improving the fatigue strength and load-bearing capacity of the matrix.

[0039] like Figure 3 As shown, the double-layer glow discharge plasma metallization process involves using a 99.99% pure chromium target and a 99.95% pure tungsten target as source electrodes. Under a substrate temperature of 480 degrees Celsius and a working pressure of 35 Pa, a glow discharge voltage of 750 volts is applied for continuous treatment for 180 minutes to form a 15-micron thick Cr / W gradient layer. The chromium concentration in the surface layer gradually decreases from 28% to 5% in the bottom layer, and the tungsten concentration decreases from 15% to 8%. The low-temperature active screen plasma nitriding process involves using a nitrogen-hydrogen mixture with a volume ratio of 3:1. Under a working pressure of 280 Pa and a pulse frequency of 15 kHz, the substrate temperature is controlled at 380 degrees Celsius for constant temperature treatment for 240 minutes to generate a 5-micron thick compound layer, in which the ε-Fe2-3N phase content is not less than 95%, and the surface hardness reaches 1350 HV0.05.

[0040] Through the synergistic construction of a dual-element gradient diffusion layer and a dense nitriding layer, a composite strengthening system is formed that combines metallurgical bonding strength with a progressive hardness transition. The chromium-tungsten gradient diffusion layer provides high-temperature stability and element interdiffusion channels, while low-temperature, highly reactive nitriding generates a dense single-phase nitriding layer, forming a continuously connected, strong and toughened matrix. This composite interface not only alleviates stress concentration in subsequent coatings but also establishes a multi-layered anti-stripping barrier through chemical affinity and dislocation pinning effects, achieving a synergistic improvement in hardness and toughness from the matrix to the surface.

[0041] like Figure 4 As shown, the magnetron sputtering transition layer deposition involved using a titanium 80 / aluminum 20 alloy target, applying a negative 100 volt substrate bias and 8 kW sputtering power under an argon flow rate of 150 standard ml / min, maintaining a deposition temperature of 180 degrees Celsius, and depositing a 0.8 μm thick nanolayered TiAlN structure at a rate of 3 nm / min. The interlayer spacing was precisely controlled at 10 nm. The high-power pulsed magnetron sputtering functional layer involved using an aluminum 70 / chromium 30 alloy target, configured with a 2500 kW pulse peak power, and setting a 50 μm... With a pulse width of 1 second and a frequency of 500 Hz, and under conditions of -800 V pulse bias, 260 °C substrate temperature, and 0.25 Pa deposition pressure for 300 minutes, a dual-structure functional layer is formed: the bottom layer is a 3 μm thick AlCrN nanocrystalline layer with a grain size of 30 nm and a stoichiometric ratio of 1:1; the surface layer is a 1.2 μm superlattice structure composed of AlCrN and AlCrON with a periodic alternation of 15 nm. The final surface hardness reaches 3500 HV0.025, and the residual compressive stress is -2.1 GPa.

[0042] Through the multi-level synergy of nanolayered transition structures and superlattice functional layers, a wear-resistant system coupling high hardness and high toughness is established. The transition layer provides interfacial strain coordination capability through the alternating stacking of nano-thick layers, alleviating the thermal expansion mismatch stress between the substrate and the coating. The functional layer forms an ultra-fine grain strong and tough substrate by means of high-energy particle bombardment, and constructs a periodically overlapping hard ceramic / oxide superlattice barrier on the surface. This dual design not only uses interfacial density to inhibit crack initiation, but also reduces the tendency of cold welding through in-situ passivation of alumina phase, ultimately achieving a qualitative change in the micron-level wear control and resistance to plastic deformation of the cutting edge under extreme shear conditions.

[0043] like Figure 5 As shown, the low-temperature ion beam mixing treatment includes using a Kaufman-type ion source with a beam energy of 800 electron volts and a beam density of 150 microamps per square centimeter, and continuously introducing 20 standard milliliters per minute of argon gas for 40 minutes to form a 120-nanometer-thick compositional gradient transition layer at the coating interface. The vacuum relaxation annealing includes isothermal annealing at 280 degrees Celsius under a vacuum of 2 x 10^-3 Pascals, holding at that temperature for 90 minutes, and then using a step cooling process of furnace cooling to 100 degrees Celsius followed by air cooling. Ultimately, the residual stress on the coating surface is reduced to -1.5 GPascals, and the interfacial shear strength is increased by 40%.

[0044] Through the dual intervention of atomic-scale interface activation and controllable stress release, the metallurgical bonding between the coating and the substrate is deeply optimized. Ion beam bombardment induces interdiffusion of interfacial elements, constructing a compositional gradient transition zone that eliminates abrupt structural changes. Simultaneously implemented sub-temperature relaxation annealing drives dislocation rearrangement, precisely reducing the peak value of interfacial shear stress. The two work together to reconstruct the residual compressive stress field on the surface into a gentle gradient distribution, improving the interface deformation coordination ability while maintaining high hardness. Ultimately, this gives the stamping cutting edge a significant leap in key performance against high-cycle fatigue spalling and stress cracking.

[0045] By deeply coordinating material phase transformation control and interface design, the inherent problem of stress mismatch in traditional composite processes is fundamentally resolved. Multi-stage deep cryogenic tempering combined with high-energy shot peening in the substrate pretreatment stage constructs a nanocrystalline reinforcement layer with gradient compression characteristics. This structure forms a stable dislocation network at the molecular scale, effectively blocking microscopic damage caused by subsequent thermal cycling. The gradient diffusion layer constructs a continuous chromium-tungsten concentration gradient and a high-purity nitride layer on the subsurface. Utilizing element affinity to disperse stress peak points, the nanolayered transition structure and superlattice functional layer in strong beam deposition form a multi-stage synergy. The alternating stacked hard phases release interfacial shear energy while maintaining ultra-high pressure stress. Finally, the stress field distribution is reconstructed through ion beam-induced diffusion and sub-temperature relaxation. The entire technology enables the mold to form an adaptive buffer system with decreasing stress from the substrate to the coating, completely solving the problem of rapid propagation of microcracks along the interface induced by stress concentration.

[0046] By overcoming the bottleneck of uncontrollable degradation in traditional heat treatment processes, the entire process is controlled at low temperatures to ensure that the core performance of the material does not degrade. The plasma infiltration temperature is strictly limited below the carbide coarsening critical point, and the gradient infiltration layer and the ultra-stable nitride layer are deposited simultaneously. The functional coating deposition adopts high-energy beam non-equilibrium synthesis technology to avoid the tensile stress accumulation caused by conventional PVD high-temperature particle bombardment. Ion beam mixing treatment completes interface healing at the atomic scale, replacing the high-temperature exposure link in the traditional equipment conversion process. This temperature-controlled system throughout the process keeps the high-speed steel matrix in a stable microstructure, fundamentally eliminating the risk of tempering softening and brittle phase precipitation. At the same time, the chromium-tungsten dispersions in the gradient strengthening layer play a thermal barrier effect, and the superlattice structure of the functional layer reduces frictional heat accumulation through periodic alumina phase passivation, so that the mold maintains a dynamic balance between surface hardness and core toughness under continuous stamping conditions.

[0047] 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 surface treatment composite process for improving the life of stamping dies, characterized in that: Includes the following steps: S1: Matrix pretreatment; S2: Preparation of gradient diffusion layer; S3: High-current deposition composite coating; S4: Post-processing; The substrate pretreatment includes vacuum cryogenic treatment and surface nano-shot peening. The gradient diffusion layer preparation includes double-layer glow discharge plasma metallization and low-temperature active screen plasma nitriding. The high-current deposition composite coating includes magnetron sputtering transition layer deposition and high-power pulsed magnetron sputtering functional layer. The post-treatment process includes low-temperature ion beam mixing treatment and vacuum relaxation annealing.

2. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The vacuum cryogenic treatment involves using SKD11 high-carbon, high-chromium steel mold material, with a chemical composition of 1.5% carbon, 12.0% chromium, 0.8% molybdenum, and 0.35% vanadium. First, the material undergoes oil quenching at 1020 degrees Celsius and holds for 30 minutes. Then, it undergoes a first-stage deep cooling in a liquid nitrogen environment to -110 degrees Celsius and holds for 90 minutes. After that, a stepped tempering process is implemented: the temperature is increased at 5 degrees Celsius per minute to +150 degrees Celsius and held for 120 minutes, then increased at 3 degrees Celsius per minute to +520 degrees Celsius and held for 180 minutes. Finally, a second-stage deep cooling is performed using a dry ice ethanol bath to -80 degrees Celsius and holds for 120 minutes.

3. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The surface nano-peening reinforcement includes using 50-micrometer diameter zirconia ceramic pellets as the peening medium to achieve 300% coverage impact treatment at a 0.35 MPa blasting pressure, forming a 20-micrometer thick nano-scale surface layer with a grain size of no more than 50 nanometers and a surface compressive stress value of -850 MPa.

4. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The double-layer glow discharge plasma metallization method includes using a 99.99% pure chromium target and a 99.95% pure tungsten target as source electrodes. Under the conditions of a substrate temperature of 480 degrees Celsius and a working pressure of 35 Pa, a glow discharge voltage of 750 volts is applied for continuous treatment for 180 minutes to form a 15-micrometer thick Cr / W gradient layer. The chromium concentration on the surface layer gradually changes from 28% to 5% on the bottom layer, and the tungsten concentration decreases from 15% to 8%.

5. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The low-temperature active screen plasma nitriding process involves using a nitrogen-hydrogen volume ratio of 3:1 mixed gas, controlling the substrate temperature at 380 degrees Celsius for 240 minutes at a working pressure of 280 Pa and a pulse frequency of 15 kHz, to generate a 5-micron thick compound layer, wherein the ε-Fe2-3N phase content is not less than 95%, and the surface hardness reaches 1350 HV0.

05.

6. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The magnetron sputtering transition layer deposition involves using a titanium 80 aluminum 20 alloy target, applying a negative 100 volt substrate bias and 8 kW sputtering power under an argon flow rate of 150 standard milliliters per minute, maintaining a deposition temperature of 180 degrees Celsius, and depositing a 0.8 micrometer thick nanolayered TiAlN structure at a rate of 3 nanometers per minute, with the interlayer spacing precisely controlled at 10 nanometers.

7. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The high-power pulsed magnetron sputtering functional layer uses an aluminum 70Cr30 alloy target, is configured with a pulse peak power of 2500 kW, a pulse width of 50 microseconds and a frequency of 500 Hz, and is processed for 300 minutes under the conditions of -800V pulse bias, 260°C substrate temperature and 0.25 Pa deposition gas pressure to form a dual-structure functional layer: the bottom layer is a 3-micrometer thick AlCrN nanocrystalline layer with a grain size of 30 nanometers and a stoichiometric ratio of 1:1, and the surface layer is a 1.2-micrometer superlattice structure composed of AlCrN and AlCrON with a periodic alternation of 15 nanometers. The final surface hardness reaches 3500HV0.025 and the residual compressive stress is -2.1 GPa.

8. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The cryogenic ion beam mixing process involves using a Kaufman-type ion source with a beam energy of 800 electron volts and a beam density of 150 microamps per square centimeter, and continuously introducing argon gas at a rate of 20 standard milliliters per minute for 40 minutes to form a 120-nanometer-thick compositional gradient transition layer at the coating interface.

9. The surface treatment composite process for improving the life of stamping dies according to claim 1, characterized in that: The vacuum relaxation annealing includes isothermal annealing at 280 degrees Celsius under a vacuum of 2 x 10 -3 Pa, followed by furnace cooling to 100 degrees Celsius and then air cooling in a stepwise manner. This process ultimately reduces the residual stress on the coating surface to -1.5 GPa and increases the interfacial shear strength by 40%.

Images