A boronizing process for martensitic stainless steel 17-4PH

Abstract

The application provides application of a boronizing agent in a surface boronizing process of martensitic stainless steel; the boronizing agent comprises 5-20 parts by weight of a boron supplier, 5-20 parts by weight of an activator and 60-90 parts by weight of a filler in terms of mass fraction. The application also provides a corresponding surface boronizing method of martensitic stainless steel. The application realizes vacuum solid surface boronizing treatment of martensitic stainless steel, improves surface hardness, does not affect core hardness, improves wear resistance and prolongs the service life of products. The application has low boronizing temperature, small material heat influence, achieves the effect of "surface hard and core soft", and the vacuum solid powder boronizing process is simple, convenient to operate, environment-friendly and suitable for batch industrial production.

Description

Technical Field

[0001] This invention belongs to the field of treatment technology for martensitic stainless steel 17-4PH, and relates to the application of boronizing agent in the boronizing process of martensitic stainless steel surface and a boronizing method for martensitic stainless steel surface, particularly the application of boronizing agent in the boronizing process of martensitic stainless steel surface and a boronizing process for martensitic stainless steel 17-4PH. Background Technology

[0002] Chemical heat treatment is one of the important processes for strengthening the surface of materials. This process involves placing the workpiece in a certain medium and heating it to a certain temperature, causing certain active components in the medium to undergo a chemical reaction on the surface of the workpiece and diffuse into the core of the workpiece, thereby changing the chemical composition of the surface layer. Subsequently, necessary heat treatment is performed to give the workpiece the required properties, thus meeting the service requirements under various working conditions.

[0003] 17-4PH (0Cr17Ni4Cu4Nb) is a chromium-nickel-copper precipitation-hardening martensitic stainless steel whose precipitated phases and properties can be controlled through heat treatment. As a commonly used precipitation-hardening stainless steel, 17-4PH (0Cr17Ni4Cu4Nb) exhibits excellent corrosion resistance, water droplet erosion resistance, cavitation erosion resistance, and certain anti-degradation properties, making it widely used in oil and gas extraction, petrochemical, marine, aerospace, and nuclear energy fields. However, due to long-term exposure to complex service environments involving high temperatures, corrosion, impact, and friction, 17-4PH components experience severe wear, erosion, and degradation, leading to unstable and unsafe long-term service. Conventional heat treatment strengthening methods are insufficient to meet the demands of industrial applications under these harsh conditions.

[0004] Therefore, finding a more suitable heat treatment strengthening method to solve the problems existing in current conventional heat treatment strengthening has become one of the urgent problems to be solved by many front-line researchers in the industry. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide the application of boronizing agent in the boronizing process of martensitic stainless steel and a method for surface boronizing of martensitic stainless steel, particularly a boronizing process for martensitic stainless steel 17-4PH. The boronizing process provided by the present invention improves surface hardness without affecting core hardness, thereby improving wear resistance and extending product lifespan. Furthermore, the boronizing method is simple, operates under mild conditions, and is highly controllable, making it more suitable for industrial-scale production and widespread application.

[0006] This invention provides the application of boronizing agent in the boronizing process of martensitic stainless steel surface;

[0007] The boronizing agent, by mass parts, comprises:

[0008] 5-20 parts by weight of boron-donating agent;

[0009] Activator 5-20 parts by weight;

[0010] 60-90 parts by weight of filler.

[0011] Preferably, the boron donor includes boron carbide and / or ferroboron;

[0012] The activator includes potassium fluoroborate and / or ammonium carbonate;

[0013] The filler includes alumina and / or silicon carbide.

[0014] Preferably, the martensitic stainless steel includes 17-4PH stainless steel;

[0015] The surface boronizing process is specifically a vacuum solid surface boronizing process.

[0016] Preferably, the surface boronizing process includes surface boronizing using vacuum heat treatment;

[0017] The surface boronizing temperature is 850–1050 °C;

[0018] The surface boronizing time is 240–600 minutes.

[0019] This invention provides a method for surface boronizing of martensitic stainless steel, comprising the following steps:

[0020] 1) Boronizing agent is obtained by mixing, drying and grinding boron donor, activator and filler;

[0021] 2) After the boronizing agent obtained in the above steps is composited on the surface of martensitic stainless steel, it is subjected to vacuum boronizing heat treatment to obtain surface boronized martensitic stainless steel.

[0022] Preferably, the drying temperature is 50–120°C;

[0023] The drying time is 30 to 60 minutes;

[0024] The grinding method includes ball milling;

[0025] The grinding time is 30 to 120 minutes.

[0026] Preferably, the thickness of the composite is 10–35 mm;

[0027] The composite on the surface of martensitic stainless steel specifically refers to the composite on at least one surface of martensitic stainless steel.

[0028] The vacuum pressure for the vacuum boronizing heat treatment is 0.010–10 Pa.

[0029] Preferably, the temperature of the vacuum boronizing heat treatment is 850–1050°C;

[0030] The vacuum boronizing heat treatment time is 240–600 minutes;

[0031] The vacuum boronizing heat treatment also includes the steps of furnace cooling or rapid cooling to 60-300°C before unloading.

[0032] Preferably, the vacuum boronizing heat treatment further includes a post-boronizing heat treatment step;

[0033] The post-distillation heat treatment methods include solution aging heat treatment;

[0034] The solution temperature for the solution aging heat treatment is 1000–1060 °C.

[0035] The solution treatment time for the solution aging heat treatment is 1 to 2.5 hours.

[0036] The solution aging heat treatment process includes a cooling step between solution treatment and aging heat treatment.

[0037] Preferably, the aging temperature of the solution aging heat treatment is 500–650°C;

[0038] The aging time for the solution aging heat treatment is 6-8 hours;

[0039] The thickness of the boronized layer on the surface-boronized martensitic stainless steel is 60–200 μm.

[0040] The boronized layer of the surface-boronized martensitic stainless steel has a hardness of 1400–1700 Hv.

[0041] This invention provides the application of a boronizing agent in the boronizing process of martensitic stainless steel. The boronizing agent, by weight, comprises 5-20 parts by weight of a boron donor, 5-20 parts by weight of an activator, and 60-90 parts by weight of a filler. Compared with existing technologies, this invention creatively applies a boronizing agent with a specific composition and ratio to the boronizing process of martensitic stainless steel, and further provides a corresponding method for surface boronizing of martensitic stainless steel. This invention achieves vacuum solid surface boronizing treatment of martensitic stainless steel, improving surface hardness without affecting core hardness, thereby improving wear resistance and extending product lifespan. This invention features low boronizing temperature and minimal heat-affected zone, achieving a "hard surface, soft core" effect. Furthermore, this vacuum solid powder boronizing process is simple, easy to operate, environmentally friendly, and suitable for mass industrial production.

[0042] Experimental results show that for martensitic stainless steel 17-4PH (0Cr17Ni4Cu4Nb), the depth of the boronizing layer is 80-100μm, the hardness of the boronizing layer is 1400-1700HV, and the core hardness is 24-33HRC. The wear resistance of the boronized product is increased by 3-6 times, and the mechanical properties meet the application requirements. Attached Figure Description

[0043] Figure 1 A schematic diagram of the vacuum solid surface boronizing process for martensitic stainless steel 17-4PH (0Cr17Ni4Cu4Nb) provided by the present invention.

[0044] Figure 2 Metallographic image of the boronized layer of the surface-boronized martensitic stainless steel prepared in Example 1 of the present invention;

[0045] Figure 3 The boronizing layer of the surface-boronized martensitic stainless steel prepared in Example 1 of this invention is shown in the elemental spectrum. Detailed Implementation

[0046] To further understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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.

[0047] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0048] There are no particular restrictions on the purity of any of the raw materials used in this invention. However, this invention preferably uses industrial-grade pure or conventionally pure materials used in the preparation of martensitic stainless steel.

[0049] This invention provides the application of boronizing agent in the boronizing process of martensitic stainless steel surface;

[0050] The boronizing agent, by mass parts, comprises:

[0051] 5-20 parts by weight of boron-donating agent;

[0052] Activator 5-20 parts by weight;

[0053] 60-90 parts by weight of filler.

[0054] In this invention, the amount of boron-donating agent added is 5 to 20 parts by weight, or 8 to 17 parts by weight, or 11 to 14 parts by weight.

[0055] In this invention, the amount of activator added is 5 to 20 parts by weight, or 8 to 17 parts by weight, or 11 to 14 parts by weight.

[0056] In this invention, the amount of filler added is 60-90 parts by weight, or 65-85 parts by weight, or 70-80 parts by weight.

[0057] In this invention, the boron-donating agent preferably includes boron carbide and / or ferroboron, more preferably boron carbide or ferroboron.

[0058] In this invention, the activator preferably includes potassium fluoroborate and / or ammonium carbonate, more preferably potassium fluoroborate or ammonium carbonate.

[0059] In this invention, the filler preferably includes alumina and / or silicon carbide, more preferably alumina or silicon carbide.

[0060] In this invention, the martensitic stainless steel includes 17-4PH stainless steel, more preferably 14-7PH stainless steel, and even more preferably 11-10PH stainless steel.

[0061] In this invention, the surface boronizing process is preferably a vacuum solid surface boronizing process.

[0062] In this invention, the surface boronizing process preferably includes surface boronizing using vacuum heat treatment.

[0063] In this invention, the surface boronizing temperature is preferably 850-1050°C, more preferably 890-1010°C, and even more preferably 930-970°C.

[0064] In this invention, the surface boronizing time is preferably 240-600 minutes, more preferably 300-550 minutes, more preferably 350-500 minutes, and even more preferably 400-450 minutes.

[0065] This invention provides a method for surface boronizing of martensitic stainless steel, comprising the following steps:

[0066] 1) Boronizing agent is obtained by mixing, drying and grinding boron donor, activator and filler;

[0067] 2) After the boronizing agent obtained in the above steps is composited on the surface of martensitic stainless steel, it is subjected to vacuum boronizing heat treatment to obtain surface boronized martensitic stainless steel.

[0068] The present invention first mixes, activators and fillers, and then dries and grinds them to obtain a boronizing agent.

[0069] In this invention, the drying temperature is preferably 50-120°C, more preferably 65-105°C, and even more preferably 80-90°C.

[0070] In this invention, the drying time is preferably 30 to 60 minutes, more preferably 35 to 55 minutes, and even more preferably 40 to 50 minutes.

[0071] In this invention, the grinding method preferably includes ball milling.

[0072] In this invention, the grinding time is preferably 30 to 120 minutes, more preferably 50 to 100 minutes, and even more preferably 70 to 80 minutes.

[0073] Finally, the boronizing agent obtained in the above steps is composited onto the surface of martensitic stainless steel, and then subjected to vacuum boronizing heat treatment to obtain surface boronized martensitic stainless steel.

[0074] In this invention, the thickness of the composite is preferably 10-35 mm, more preferably 15-30 mm, and even more preferably 20-25 mm.

[0075] In this invention, the composite on the surface of martensitic stainless steel is preferably composited on at least one surface of martensitic stainless steel, but it can also be composited on two corresponding surfaces, or four or six corresponding surfaces, or composited on all surfaces. Specifically, the surface to be protected is excluded.

[0076] In this invention, the vacuum pressure of the vacuum boronizing heat treatment is preferably 0.010 to 10 Pa, more preferably 0.10 to 6 Pa, and even more preferably 1 to 2 Pa.

[0077] In this invention, the temperature of the vacuum boronizing heat treatment is preferably 850-1050°C, more preferably 890-1010°C, and even more preferably 940-970°C.

[0078] In this invention, the vacuum boronizing heat treatment time is preferably 240-600 minutes, more preferably 300-550 minutes, more preferably 350-500 minutes, and even more preferably 400-450 minutes.

[0079] In this invention, the vacuum boronizing heat treatment preferably includes a step of cooling or rapidly cooling to 60-300°C before exiting the furnace, more preferably a step of cooling or rapidly cooling to 100-250°C before exiting the furnace, and even more preferably a step of cooling or rapidly cooling to 150-200°C before exiting the furnace.

[0080] In this invention, the vacuum boronizing heat treatment preferably includes a post-boronizing heat treatment step.

[0081] In this invention, the post-diffusion heat treatment method preferably includes solution aging heat treatment.

[0082] In this invention, the solution temperature of the solution aging heat treatment is preferably 1000-1060℃, more preferably 1010-1050℃, and even more preferably 1020-1040℃.

[0083] In this invention, the solution treatment time for the solution aging heat treatment is preferably 1 to 2.5 h, more preferably 1.3 to 2.2 h, and even more preferably 1.6 to 1.9 h.

[0084] In this invention, the solution aging heat treatment process preferably includes a cooling step between solution aging and heat treatment.

[0085] In this invention, the aging temperature of the solution aging heat treatment is preferably 500-650°C, more preferably 530-620°C, and even more preferably 560-590°C.

[0086] In this invention, the aging time of the solution aging heat treatment is preferably 6 to 8 hours, more preferably 6.4 to 7.6 hours, and even more preferably 6.8 to 7.2 hours.

[0087] In this invention, the thickness of the boronized layer of the surface-boronized martensitic stainless steel is preferably 60-200 μm, more preferably 65-180 μm, more preferably 70-150 μm, more preferably 75-130 μm, and more preferably 80-100 μm.

[0088] In this invention, the hardness of the boronized layer of the surface-boronized martensitic stainless steel is preferably 1400-1700 Hv, more preferably 1450-1650 Hv, and even more preferably 1500-1600 Hv.

[0089] To complete and refine the overall technical solution, this invention better ensures the boronizing effect, stability, and controllability of the above-mentioned boronizing process for martensitic stainless steel, and further improves the surface hardness, wear resistance, and service life of martensitic stainless steel. The above-mentioned surface boronizing method for martensitic stainless steel may specifically include the following steps:

[0090] A vacuum solid surface boronizing process for martensitic stainless steel, comprising the following main process steps: preparation of boronizing agent (P1), product cleaning (P2), loading into containers (P3), loading into the furnace (P4), vacuum boronizing (P5), post-boroning heat treatment (P6), product cleaning (P7), product testing (P8), and warehousing of qualified products (P9).

[0091] See Figure 1 , Figure 1 A schematic diagram of the vacuum solid surface boronizing process for martensitic stainless steel 17-4PH (0Cr17Ni4Cu4Nb) provided by the present invention.

[0092] Wherein: P1 is the preparation of boronizing agent, P2 is product cleaning, P3 is loading into containers, P4 is loading into the furnace, P5 is vacuum boronizing, P6 is post-boronizing heat treatment, P7 is product cleaning, P8 is product testing, and P9 is the warehousing of qualified products.

[0093] Specifically, the vacuum solid surface boronizing process is applicable to all known martensitic stainless steels, especially 17-4PH (0Cr17Ni4Cu4Nb) stainless steel.

[0094] Specifically, the boronizing agent in the preparation of the P1 boronizing agent includes boron donor, activator, filler, etc.

[0095] Specifically, the boron-donating agent is one or more of boron carbide, ferroboron, etc., accounting for 5-20%.

[0096] Specifically, the activator is one or more of potassium fluoroborate KBF4, ammonium carbonate (NH4)2CO3, etc., accounting for 5-20%.

[0097] Specifically, the filler is one or more of alumina (Al2O3), silicon carbide (SiC), etc., accounting for 60-90%.

[0098] Specifically, the boronizing agent is weighed according to the components P11, then sieved and mixed P12, dried once P13, ball-milled and mixed P14, and dried a second time P15.

[0099] Specifically, the P12 mixture is sieved and mixed using a sieve with a mesh size of 30-200.

[0100] Specifically, P13 is dried once and P15 is dried twice, at a temperature of 50-120℃ for 30-60 minutes.

[0101] Specifically, the P14 ball milling process takes 30-120 minutes.

[0102] Specifically, the P3 container has a 10-35mm thick layer of boronizing agent powder pre-placed at the bottom, compacted without gaps or holes; the distance between the workpiece and the container wall is 5-20mm, and the distance between the workpieces is about 5-20mm; the top of the workpiece is covered with a 10-35mm thick layer of boronizing agent powder and compacted; the container lid is closed tightly and sealed if necessary.

[0103] Specifically, the P4 furnace is a boronizing furnace, which is a vacuum heating furnace with argon gas replacement protection function, a maximum temperature of 900-1200℃, and a vacuum degree of 0.010-10Pa.

[0104] Specifically, the P5 vacuum boronizing process involves a boronizing temperature of 850-1050℃, a holding time of 240-600 minutes, and furnace cooling or rapid cooling to 60-300℃ before exiting the furnace.

[0105] Specifically, the P6 post-diffusion heat treatment is a solution aging heat treatment with a solution temperature of 1000-1060℃, held for 1-2.5 hours and then air-cooled to room temperature. The aging treatment is held at 500-650℃ for 6-8 hours and then air-cooled to room temperature.

[0106] When the boronizing temperature is low and has little impact on the material, the P6 post-boronizing heat treatment can be omitted.

[0107] See Table 1, which shows the technical specifications of the boronizing layer in the boronizing process for martensitic stainless steel provided by this invention.

[0108] Table 1

[0109]

[0110] See Table 2, which shows the mechanical properties of martensitic stainless steel before and after boronizing process provided by the present invention.

[0111] Table 2

[0112]

[0113] This invention provides the application of boronizing agents in the boronizing process of martensitic stainless steel and a boronizing process for martensitic stainless steel 17-4PH. This invention uses boronizing agents with specific compositions and ratios in the boronizing process of martensitic stainless steel, and further provides a corresponding method for surface boronizing of martensitic stainless steel. This invention achieves vacuum solid surface boronizing treatment of martensitic stainless steel, improving surface hardness without affecting core hardness, thereby improving wear resistance and extending product lifespan. This invention features low boronizing temperature and minimal heat-affected zone, achieving a "hard surface, soft core" effect. Furthermore, this vacuum solid powder boronizing process is simple, easy to operate, environmentally friendly, and suitable for mass industrial production.

[0114] Experimental results show that for martensitic stainless steel 17-4PH (0Cr17Ni4Cu4Nb), the depth of the boronizing layer is 80-100μm, the hardness of the boronizing layer is 1400-1700HV, and the core hardness is 24-33HRC. The wear resistance of the boronized product is increased by 3-6 times, and the mechanical properties meet the application requirements.

[0115] To further illustrate the present invention, the following describes in detail, with reference to embodiments, the application of the boronizing agent provided by the present invention in the boronizing process of martensitic stainless steel and a method for boronizing the surface of martensitic stainless steel. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures, only to further illustrate the features and advantages of the present invention, and not to limit the scope of protection of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0116] Example 1

[0117] The main process flow for vacuum solid surface boronizing of martensitic stainless steel 17-4PH (0Cr17Ni4Cu4Nb) is as follows: boronizing agent preparation P1, product cleaning P2, loading into containers P3, loading into the furnace P4, vacuum boronizing P5, post-boroning heat treatment P6, product cleaning P7, product inspection P8, and qualified product warehousing P9.

[0118] The boronizing agent is formulated by comprising a boron donor, an activator, and a filler. The boron donor is boron carbide and ferroboron, accounting for 10% of the total. The activator is potassium fluoroborate and ammonium carbonate, accounting for 10% of the total. The filler is alumina and silicon carbide, accounting for 80% of the total.

[0119] After weighing the boronizing agents according to their components, they are sieved and mixed, then subjected to a first drying, ball milling, and a second drying. The sieving process is carried out at a 200-mesh screen, at 100℃ for 60 minutes, and the ball milling process is carried out for 100 minutes.

[0120] Place a 30mm thick layer of boronizing agent powder at the bottom of the container, compact it without gaps or holes; keep a 20mm distance between the workpiece and the container wall, and about 20mm between workpieces; cover the top of the workpiece with a 30mm thick layer of boronizing agent powder and compact it; close the container lid tightly, and seal it if necessary.

[0121] The container is placed in a vacuum heating furnace with argon replacement gas protection function for vacuum boronizing. The vacuum degree is 0.010~10 Pa, the boronizing temperature is 1000℃, and the holding time is 400 minutes. The container is then cooled in the furnace or rapidly cooled to 100℃ before being removed from the furnace.

[0122] The obtained martensitic stainless steel was subjected to post-diffusion heat treatment, namely solution aging heat treatment at 1050℃, holding at 1050℃ for 2 hours and then air-cooled to room temperature, followed by aging treatment at 650℃ for 5 hours and then air-cooled to room temperature, to obtain surface boronized martensitic stainless steel.

[0123] The surface boronized martensitic stainless steel prepared in Example 1 of the present invention was tested.

[0124] The results show that the boronized layer has a depth of 100 μm, a hardness of 1550–1600 HV, and a core hardness of 28–30 HRC. The wear resistance ratio of the boronized product is 3 times higher than that of the unboronized martensitic stainless steel, and its mechanical properties meet the application requirements.

[0125] The tensile strength Rm is 1050-1100MPa, the yield strength Rp0.2 is 1000-1050MPa, the impact energy is 103J, the elongation after fracture A25mm is 13%, and the reduction of area Z is 60%.

[0126] The surface boronized martensitic stainless steel prepared in Example 1 of the present invention was characterized.

[0127] See Figure 2 , Figure 2 Metallographic image of the boronized layer of the surface-boronized martensitic stainless steel prepared in Example 1 of the present invention.

[0128] See Figure 3 , Figure 3 The boronizing layer of the surface-boronized martensitic stainless steel prepared in Example 1 of this invention is shown in the elemental spectrum.

[0129] Example 2

[0130] The process flow and process parameters before and after P5 are the same as in Example 1. The difference is that the boronizing temperature of vacuum boronizing is 900℃, the holding time is 500 minutes, and it is cooled with the furnace or rapidly cooled to 100℃ before being taken out of the furnace.

[0131] The surface boronized martensitic stainless steel prepared in Example 2 of the present invention was tested.

[0132] The results show that the depth of the boronized layer is 90 μm, the hardness of the boronized layer is 1500–1550 HV, and the core hardness is 28–30 HRC.

[0133] The tensile strength Rm is 1100-1150MPa, the yield strength Rp0.2 is 1050-1100MPa, the impact energy is 110J, the elongation after fracture A25mm is 15%, and the reduction of area Z is 65%.

[0134] Example 3

[0135] The process flow and process parameters before and after P5 are the same as in Example 1. The difference is that the boronizing temperature of vacuum boronizing is 850°C, the holding time is 600 minutes, and it is cooled in the furnace or rapidly cooled to 100°C before being taken out of the furnace.

[0136] The surface boronized martensitic stainless steel prepared in Example 3 of the present invention was tested.

[0137] The results show that the depth of the boronized layer is 90 μm, the hardness of the boronized layer is 1450–1500 HV, and the core hardness is 28–30 HRC.

[0138] The tensile strength Rm is 1150-1200MPa, the yield strength Rp0.2 is 1100-1150MPa, the impact energy is 115J, the elongation after fracture A25mm is 19%, and the reduction of area Z is 68%.

[0139] The application of the boronizing agent provided by this invention in the boronizing process of martensitic stainless steel and a boronizing process for martensitic stainless steel 17-4PH have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The above descriptions of the embodiments are only for the purpose of helping to understand the method and core ideas of this invention, including the best mode, and also to enable any person skilled in the art to practice this invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A vacuum surface boronizing method for martensitic stainless steel, characterized in that, Includes the following steps: 1) Boronizing agent is obtained by mixing, drying and grinding boron donor, activator and filler; The boronizing agent, by mass parts, consists of the following components: 5-20 parts by weight of boron-donating agent; Activator 5-20 parts by weight; 60-90 parts by weight of filler; The boron-donating agent is boron carbide and ferroboron; The activator is potassium fluoroborate and ammonium carbonate; The filler is aluminum oxide and silicon carbide; 2) After the boronizing agent obtained in the above steps is composited on the surface of martensitic stainless steel, it is subjected to vacuum boronizing heat treatment to obtain surface boronized martensitic stainless steel. The thickness of the composite is 10~35mm; The martensitic stainless steel includes 17-4PH stainless steel; The vacuum pressure for the vacuum boronizing heat treatment is 0.010~10 Pa; The temperature of the vacuum boronizing heat treatment is 850~1050℃; The vacuum boronizing heat treatment time is 240~600 minutes; The vacuum boronizing heat treatment also includes a post-boronizing heat treatment step. The post-distillation heat treatment methods include solution aging heat treatment; The solution temperature for the solution aging heat treatment is 1000~1060℃; The solution treatment and aging heat treatment time is 1~2.5h; The aging temperature of the solution aging heat treatment is 500~650℃; The aging time for the solution aging heat treatment is 6-8 hours. The thickness of the boronized layer on the surface-boronized martensitic stainless steel is 60~200μm. The core hardness of the boron-dipped martensitic stainless steel is 24~33 HRC.

2. The vacuum surface boronizing method according to claim 1, characterized in that, The drying temperature is 50~120℃.

3. The vacuum surface boronizing method according to claim 1, characterized in that, The drying time is 30-60 minutes.

4. The vacuum surface boronizing method according to claim 1, characterized in that, Grinding methods include ball milling.

5. The vacuum surface boronizing method according to claim 1, characterized in that, The grinding time is 30-120 minutes.

6. The vacuum surface boronizing method according to claim 1, characterized in that, The composite on the surface of martensitic stainless steel specifically refers to the composite on at least one surface of martensitic stainless steel.

7. The vacuum surface boronizing method according to claim 1, characterized in that, The vacuum boronizing heat treatment also includes the steps of furnace cooling or rapid cooling to 60~300°C before unloading.

8. The vacuum surface boronizing method according to claim 1, characterized in that, The solution aging heat treatment process includes a cooling step between solution treatment and aging heat treatment.

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