Directional solidification high-boron high-speed steel jet nozzle for oil field hydraulic power and preparation method thereof

Abstract

The invention discloses a directional solidification high-boron high-speed steel jet nozzle for oil field hydraulic power and a preparation method thereof, and belongs to the technical field of oil field exploitation equipment. The preparation method comprises the steps that raw materials such as electrical pure iron and micro-carbon ferrochrome are proportioned according to the specific mass fraction, and high-boron high-speed steel molten steel is obtained through vacuum melting; after the molten steel is subjected to rare earth aluminum desulfurization and temperature control, an as-cast blank is obtained through directional solidification treatment; and the cast blank is subjected to machining, austenitizing quenching, tempering heat treatment and fine polishing treatment, and a finished product is obtained. The finished product comprises a metal matrix and a directionally-arranged (Fe, Cr) 2B boride hard phase, alloy components are accurate and controllable, the hardness is 58.5-64.5 HRC, and the surface roughness is 0.25-0.40 mu m. The high-wear-resistance and high-brittleness high-wear-resistance and high-performance alloy nozzle has low cost and high performance, the problems that a traditional nozzle is poor in wear resistance, high in cost and large in brittleness are solved, the service life is remarkably prolonged, and the high-wear-resistance and high-brittleness high-wear-resistance and high-brittleness high-wear-resistance high-brittleness high-wear-resistance high-brittleness high-wear-resistance high-brittleness high-

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oilfield exploitation equipment, and particularly relates to a directional solidification high-boron high-speed steel jetting nozzle for oilfield hydraulic and a preparation method thereof. BACKGROUND

[0002] In the field of oilfield exploitation, the wear-resistant nozzle of the hydraulic jetting tool needs to withstand microscopic cutting damage of high-pressure jet flow containing sand as an important and vulnerable component, and its service life and use cost directly determine the working efficiency of the hydraulic jetting tool.

[0003] Traditional jetting tools are usually made of the following three materials: The high-performance wear-resistant nozzle adopts a composite structure of a steel matrix + hard alloy nozzle, but the hard alloy has high cost and high brittleness, is prone to failure, and the steel / hard alloy interface has a serious stress cracking risk; The ordinary steel nozzle has low production cost, but has insufficient wear resistance and a service life of less than 200 hours; The traditional high-speed steel nozzle has high hardness, but has a complex production process, high content of precious metals (such as Mo, W, V, etc.), significantly high production cost, and uneven distribution of carbides, which results in poor toughness and fatigue resistance, and the service safety of the nozzle cannot be guaranteed.

[0004] High-boron high-speed steel replaces C elements with B elements, and replaces hard carbide phases with borides with higher hardness and stability, flexibly controls the metal matrix and hard phases of the alloy, reduces the addition amount of precious metal elements, and significantly reduces the production cost of high-speed steel, so that the high-boron high-speed steel can balance the production cost and reliable service performance in various wear service conditions. Microscopic cutting wear caused by sand splashing on the tool body is the main cause of failure, but the above-mentioned existing material tools have a series of service shortcomings, and therefore a new material structure with high wear resistance, low cost and impact resistance needs to be developed. SUMMARY

[0005] The technical problem to be solved by the application is to provide a directional solidification high-boron high-speed steel jetting nozzle for oilfield hydraulic and a preparation method thereof to solve the technical problem that the wear resistance, toughness and production cost of the existing oilfield hydraulic jetting nozzle are difficult to balance, obtain high-boron high-speed steel with Cr-toughened Fe2B hard phase directional arrangement and high-density fine second-phase particles at low cost, significantly improve the cost-effectiveness of the oilfield hydraulic jetting tool, and provide a new idea for the application of high-boron high-speed steel in the field of oilfield exploitation.

[0006] The application adopts the following technical solutions: The application discloses a preparation method of a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic use. S1, vacuum smelting treatment is performed on electrically pure iron, micro-carbon chromium iron, tungsten iron, molybdenum iron, pig iron, manganese iron and silicon iron as raw materials to obtain high-boron high-speed steel liquid steel; S2, temperature control treatment is performed on the high-boron high-speed steel liquid steel obtained in the step S1, and then the high-boron high-speed steel liquid steel is transferred to a directional solidification device to perform directional solidification treatment, so that a cast blank with directional solidification structure is obtained; S3, the cast blank obtained in the step S2 is sequentially subjected to mechanical processing, austenitizing quenching and tempering heat treatment, so that the directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic use is obtained.

[0007] Preferably, in the step S1, the raw materials include, in terms of mass fraction, 62.069%-70.700% of electrically pure iron, 9.509%-11.175% of micro-carbon chromium iron, 4.388%-4.938% of tungsten iron, 1.736%-2.463% of molybdenum iron, 9.239%-11.127% of boron iron, 3.397%-7.405% of pig iron, 0.550%-0.700% of manganese iron and 0.096%-0.481% of silicon iron.

[0008] Preferably, in the step S1, the vacuum smelting specifically includes the following steps. First, the electrically pure iron, the micro-carbon chromium iron, the tungsten iron, the molybdenum iron, the pig iron, the manganese iron and the silicon iron are melted into liquid steel at 1550-1580 DEG C; The liquid steel is transferred to a ladle for ladle heating treatment; Then, the boron iron which is kept at 300 DEG C for 40-60 min is added, and is subjected to re-melting, so that the temperature of the liquid steel is increased to 1500-1540 DEG C for keeping, and the high-boron high-speed steel liquid steel is obtained.

[0009] Preferably, in the step S2, the temperature control treatment includes the following steps. 0.008%-0.012% of rare earth aluminum in terms of the mass of the liquid steel is added to the liquid steel for desulfurization treatment, and the temperature of the liquid steel is controlled to be reduced to 1350-1400 DEG C.

[0010] Preferably, in the step S2, the process parameters of the directional solidification treatment are as follows. The solidification interface temperature gradient is 100-200 K / cm, and the pulling rate is 3-8 mm / min.

[0011] Preferably, in the step S3, the austenitizing quenching and tempering heat treatment specifically includes the following steps. The workpiece after the mechanical processing is heated to 1040-1110 DEG C at a rate of 10-20 DEG C / min under vacuum, and is subjected to oil quenching after keeping for 60-120 min. The quenched workpiece is tempered under vacuum condition, the tempering temperature is 525-605 DEG C, the holding time is 55-65 min, and the tempering treatment is repeated at least 3 times.

[0012] Preferably, after the tempering heat treatment, the inner wall of the flow channel of the spray head is further subjected to surface finishing treatment, the finishing treatment adopts diamond grinding wheel, the polishing medium is 10vol.% water-based 2.5 μm SiO2 suspension, and the polishing time is 120-180 s.

[0013] Another technical scheme of the application is a directional solidification high-boron high-speed steel spray head for oilfield hydraulic use, which is characterized by being prepared by the preparation method, and comprises a metal base and boride hard phases distributed on the base, and the alloy composition is C: 0.21%-0.37%, B: 1.76%-2.12%, Cr: 5.42%-6.37%, Mo: 1.05%-1.49%, W: 3.51%-3.95%, Mn: 0.44%-0.56%, Si: 0.40%-0.60% by weight percentage, and the rest is Fe and inevitable trace impurities.

[0014] Preferably, the hardness of the spray head is 58.5-64.5 HRC, the surface roughness Ra of the inner wall of the flow channel is 0.25-0.40 μm, the microstructure of the spray head comprises tempered martensite base and (Fe, Cr)2B boride hard phases arranged directionally on the base.

[0015] Preferably, the directional solidification direction of the spray head is perpendicular to the inner wall direction of the nozzle.

[0016] Compared with the prior art, the application has at least the following beneficial effects: A directional solidification high-boron high-speed steel spray head preparation method for oilfield hydraulic use adopts vacuum induction melting process to smelt high-boron high-speed steel liquid, avoids the introduction of impurity elements and the burning loss of raw materials, and improves the accuracy of alloy chemical composition and the stability of performance. The directional solidification pulling method is adopted to prepare the as-cast high-boron high-speed steel blank, the directional solidification parameters can be adjusted in a large range, so that the alloy microstructure form can be controlled according to the service performance requirements, and a workpiece with excellent service performance in a specific direction can be obtained. The as-cast directional solidification high-boron high-speed steel is subjected to austenitizing + tempering process, the sharp corners of the boride hard phase skeleton are passivated, and a large amount of dispersed precipitated phase is obtained, the abrasive wear resistance, bending strength and fatigue resistance of the directional solidification high-boron high-speed steel oilfield hydraulic spray tool are significantly improved. The core of the application lies in the alloy composition design conducive to the formation of directional solidification hard phase texture, the smelting of high-boron high-speed steel liquid, the directional solidification texture control technology, and the directional solidification high-boron high-speed steel hardening and tempering heat treatment technology.

[0017] Further, the content of Cr element in the alloy is 5.42%~6.37%, at this content, the boride hard phase of high boron high speed steel is (Fe, Cr)2B of tetragonal structure, which can grow along <002> direction to obtain rod-shaped directional arrangement of boride texture under directional solidification process, significantly improving the strength and wear resistance of the workpiece at the vertical interface of the solidification direction; the total content of Mo and W elements is controlled within 5%, which significantly reduces the production cost of raw materials of high boron high speed steel, and the elements dissolved in the boride hard phase further improve the hardness and toughness of the boride, and the elements dissolved in the metal matrix improve the hardenability of the alloy, which helps to reduce the heat treatment cost; the content of C element is controlled at 0.21%~0.37%, which can obtain low-carbon tempered martensite structure after heat treatment, which has high hardness and toughness, and can further improve the service safety of the workpiece.

[0018] Further, in the vacuum melting process, the melting temperature before adding boron iron is 1540~1580℃, which is higher than the melting point of pure iron 1538℃, so that various raw materials can be quickly melted to ensure sufficient thermal flow stirring and melting of the molten steel, and the homogenization and cleanliness of the melt are improved; the boron iron is preheated at 300℃ for 40~60min, which can improve the yield of boron element.

[0019] Further, in the directional solidification process, the solidification interface temperature gradient and the pulling speed are controlled to control the solidification speed of high boron high speed steel, so as to realize the regulation of the directional organization parameters (such as primary metal matrix grain size and eutectic boride lamellar spacing) of the same composition alloy, and to realize the regulation of the service performance of the directional solidification high boron high speed steel.

[0020] Further, austenitizing at 1040~1110℃ for 60~120min, so that the metal matrix of high boron high speed steel is completely converted into austenite, and part of the carbides and borides around the matrix are broken and dissolved, thereby improving the hardness and toughness of the high boron high speed steel workpiece; the tempering temperature is set to 525~605℃, and the furnace is cooled to room temperature, and the tempering treatment is repeated for 3 times, which can effectively release the internal stress generated in the quenching process, promote the tempering precipitation hardening effect of M7(C, B)3, M6(C, B), M6(C, B) and other hard and fine second phase particles on the tempered martensite matrix, and improve the stability of the alloy organization, especially the tempered martensite and the precipitated fine second phase particles, thereby improving the service performance stability and service safety of the workpiece.

[0021] The directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic use has components and structural design, so that the product has high hardness (boride hard phase) and good toughness (metal matrix), and solves the problems of large brittleness of traditional hard alloy, poor wear resistance of ordinary steel, and high cost of traditional high-speed steel. Precise limitation of the component range ensures stable and controllable product performance, avoids performance fluctuations caused by component deviation, and provides structural and component protection for reliable service of the product in the high-pressure sand-containing environment of the oilfield.

[0022] Further, the hardness of 58.5-64.5 HRC and the surface roughness of 0.25-0.40 μm accurately match the service requirements of the oilfield hydraulic jet. The directional arrangement of (Fe, Cr) 2B boride and the tempered martensite matrix synergistically act to achieve a balance between wear resistance and impact resistance. Compared with existing products, this combination of performance parameters solves the problems of insufficient hardness, poor wear resistance, or insufficient toughness and easy breakage of traditional nozzles, ensures long-term stable operation of the nozzle in the high-pressure sand-containing jet environment, and significantly improves the service life and use cost ratio.

[0023] Further, the directional solidification direction is perpendicular to the inner wall of the nozzle, so that the hard phase is arranged along the erosion stress direction to form targeted protection. This design allows the inner wall of the nozzle to directly resist the microscopic cutting and erosion of sand particles, solving the problem of disordered arrangement of the hard phase and insufficient erosion resistance of traditional products. The optimization of the directional solidification direction further enhances the wear resistance, significantly reduces the wear rate of the nozzle in the high-pressure sand-containing working condition, further prolongs the service life, and improves the use efficiency ratio.

[0024] In summary, the directional solidification high-boron high-speed steel oilfield hydraulic jet tool manufactured by the vacuum melting + directional solidification + heat treatment process in the present application has a tempered martensite- (Fe, Cr) 2B dual-phase columnar crystal organization, and a high-density tempered precipitated hard particle in the tempered martensite, so that the service life and performance of the oilfield hydraulic jet tool are greatly improved, and the cost ratio is higher than that of existing oilfield hydraulic jet tools.

[0025] The technical solutions of the present application will be further described in detail below with the aid of drawings and examples. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the relative example description are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 The manufacturing flowchart of the present application; Figure 2 Schematic diagram of the oilfield hydraulic jet tool of the present application; Figure 3 SEM photo of the heat treated directional solidification high boron high speed steel obtained in Example 1; Figure 4 Actual photos of the oilfield hydraulic jet nozzle of the directional solidification high boron high speed steel and the oilfield hydraulic jet nozzle of cemented carbide after 1800h service under the test conditions of Example 1, wherein (a) is the oilfield hydraulic jet nozzle of the directional solidification high boron high speed steel, and (b) is the oilfield hydraulic jet nozzle of cemented carbide. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0030] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0031] In the present application, the percentage (%) or the part refers to the percentage by weight or the weight part of the composition, if not otherwise specified.

[0032] In the present application, the components or the preferred components thereof mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0033] In the present application, the numerical range "a~b" represents the abbreviation of any real number combination between a and b, wherein a and b are both real numbers, if not otherwise specified. For example, the numerical range "6~22" represents that all the real numbers between "6~22" have been listed in the present application, and "6~22" is only the abbreviation of these numerical combinations.

[0034] The lower limit and the upper limit of the range disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

[0035] In the present application, the term "and / or" used in the present application means any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0036] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or in sequence.

[0037] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to that described can also be applied in the present application.

[0038] The present application provides an oilfield hydraulic directional solidification high boron high speed steel jet nozzle and its preparation method, relates to a wear-resistant material processing technology based on directional solidification high boron high speed steel, and obtains high boron high speed steel with Cr toughened Fe2B hard phase directional arrangement and high-density fine second phase particles by a low-cost production processing technology, significantly improves the cost-effectiveness ratio of the oilfield hydraulic jet tool, and provides a new idea for the application of high boron high speed steel in the field of oilfield exploitation.

[0039] Please refer to Figure 1 The present application provides an oilfield hydraulic directional solidification high boron high speed steel jet nozzle and its preparation method, relates to a wear-resistant material processing technology based on directional solidification high boron high speed steel, and obtains high boron high speed steel with Cr toughened Fe2B hard phase directional arrangement and high-density fine second phase particles by a low-cost production processing technology, significantly improves the cost-effectiveness ratio of the oilfield hydraulic jet tool, and provides a new idea for the application of high boron high speed steel in the field of oilfield exploitation. S1, the pure iron, the micro-carbon chromium iron, the tungsten iron, the molybdenum iron, the pig iron, the manganese iron, the silicon iron are used as raw materials, and vacuum melting treatment is carried out at 1550~1580 DEG C, and refined molten steel is obtained; The mass fraction of the pure iron in the raw material is 62.069%~70.700%, the mass fraction of the micro-carbon chromium iron is 9.509%~11.175%, the mass fraction of the tungsten iron is 4.388%~4.938%, the mass fraction of the molybdenum iron is 1.736%~2.463%, the mass fraction of the boron iron is 9.239%~11.127%, the mass fraction of the pig iron is 3.397%~7.405%, and the mass fraction of the manganese iron is 0.550%~0.700%, and the mass fraction of the silicon iron is 0.096%~0.481%.

[0040] The vacuum melting is specifically as follows: First, the pure iron, the micro-carbon chromium iron, the tungsten iron, the molybdenum iron, the manganese iron and the pig iron are added to the vacuum induction furnace, and the temperature is raised to 1550~1580 DEG C after the furnace charge is completely melted; Then, the molten steel is transferred to the ladle for ladle treatment, and the boron iron with 300 DEG C insulation for 40~60 min is added to the induction furnace, the molten steel in the ladle is remelted, the molten steel temperature is raised to 1500~1540 DEG C again, and the molten steel is kept for 10 min, to obtain pure high boron high speed steel.

[0041] S2. Temperature control treatment is applied to the molten steel obtained in step S1 to control the temperature of the high boron high speed steel molten steel to be reduced to 1350~1400℃ and then transferred to a vacuum pulling furnace for directional solidification treatment to obtain directional solidified high boron high speed steel cast billet. The temperature control process is as follows: After the hot ladle treatment, place rare earth aluminum at the bottom of the ladle, equivalent to 0.008%~0.012% of the molten steel mass. Pour the molten steel into the ladle for desulfurization treatment. When the temperature of the molten steel drops to 1350~1400℃, transfer it to an industrial vacuum clinker furnace.

[0042] Directional solidification specifically refers to: Directional solidification was carried out in an industrial-grade directional solidification pulling furnace. The solidification interface temperature gradient was 100~200K / cm, the pulling rate was 3~8mm / min, and the obtained directional solidification ingot size was Φ80×250mm.

[0043] S3. The as-cast billet obtained in step S2 is subjected to rough machining, austenitization and tempering heat treatment, and surface polishing to obtain a directional solidification high boron high-speed steel oilfield hydraulic jet nozzle.

[0044] The specific machining process is as follows: The casting billet is rough machined into a tool body of Φ65×220mm using a lathe, and four nozzle channels with a diameter of 4.5±0.1mm are evenly drilled on the end face using a drilling machine.

[0045] The austenitizing and tempering heat treatment specifically includes: The workpiece to be processed is placed in a vacuum resistance furnace and heated to 1040~1110℃ at a heating rate of 10~20℃ / min for austenitization and holding for 60~120min. Then, it is quenched in vacuum quenching oil. Next, the quenched workpiece is placed in a vacuum resistance furnace and heated to the tempering temperature of 525~605℃ and held for 55~65 minutes. Then, it is cooled to room temperature in the furnace and the tempering process is repeated 3 times.

[0046] The specific surface polishing process is as follows: The inner wall of the flow channel was polished using a diamond grinding wheel for 120-180 seconds. The polishing medium was a 10 vol.% water-based 2.5 μm SiO2 suspension.

[0047] A high-boron high-speed steel jet nozzle for oilfield hydraulic applications, prepared using the method described above, comprises a metal matrix and a boride hard phase distributed on the matrix. By weight percentage, the alloy composition is: C: 0.21%~0.37%, B: 1.76%~2.12%, Cr: 5.42%~6.37%, Mo: 1.05%~1.49%, W: 3.51%~3.95%, Mn: 0.44%~0.56%, Si: 0.40%~0.60%, with the remainder being Fe and unavoidable trace impurities. The nozzle workpiece hardness is 58.5~64.5 HRC; the surface roughness Ra of the inner wall of the flow channel is 0.25~0.40 μm.

[0048] The heat-treated directionally solidified high-boron high-speed steel has a high-density, finely dispersed tempered martensite matrix and a directionally arranged rod-shaped (Fe,Cr)2B hard phase. Cr, Mo, and W elements can improve the matrix strength and hardenability, as well as the hardness and toughness of the boride hard phase. B element can form rod-shaped eutectic boride hard phase and improve the matrix hardenability, which determines the wear resistance of high-boron high-speed steel. The addition of C can promote the formation of tempered martensite in the matrix, improving the wear resistance and service safety of the material.

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] Example 1 Water jet tool manufacturing and processing This invention uses electrical pure iron, micro-carbon ferrochrome, ferromolybdenum, ferrotungsten, ferroboron, pig iron, ferrosilicon, and ferromanganese as raw materials. 62.069% electrical pure iron (chemical composition of electrical pure iron: 0.020% C, 0.020% Si, 0.150% Mn, balance Fe) is added respectively, along with 11.175% micro-carbon ferrochrome (chemical composition of micro-carbon ferrochrome: 0.060% C, 57.000% Cr, 1.450% Si, balance Fe), 1.736% ferromolybdenum (chemical composition of ferromolybdenum: 0.021% C, 0.510% Si, 60.500% Mo, balance Fe), and 4.938% ferrotungsten (chemical composition of ferrotungsten: 0.100% C, 0.500% Si, 80.50% Mn, balance Fe), and 80% ferromanganese. 0.000%W, balance Fe), 11.127% ferroboron (ferroboron has a chemical composition of 0.380%C, 0.490%Si, 19.050%B, balance Fe), 7.405% pig iron (pig iron has a chemical composition of 4.270%C, 0.900%Si, 0.113%Mn, balance Fe), % ferrosilicon (ferrosilicon has a chemical composition of 0.210%C, 72.200%Si, balance Fe), 0.550% ferromanganese (ferrosilicon has a chemical composition of 1.500%C, 1.500%Si, 80.000%Mn, balance Fe).

[0051] The specific preparation process of this invention is as follows: S1. Using electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon as raw materials, vacuum melting is carried out at 1580℃. Then, the molten steel is transferred to a ladle for hot ladle treatment. Boron iron that has been held at 300℃ for 60 minutes is added to the induction furnace. The molten steel in the ladle is then returned to the furnace for remelting. The temperature of the molten steel is raised again to 1540℃ and held for 10 minutes to obtain pure high-boron high-speed steel. S2. Temperature control treatment is applied to the molten steel obtained in step S1. Rare earth aluminum equivalent to 0.012% of the molten steel mass is placed at the bottom of the ladle after the hot ladle treatment. The molten steel is then poured into the ladle for desulfurization treatment. The temperature of the high boron high-speed steel is controlled to decrease to 1350℃ and then transferred to an industrial-grade directional solidification pulling furnace for directional solidification treatment. The solidification interface temperature gradient is 200K / cm, the pulling rate is 8mm / min, and the obtained directional solidification ingot size is Φ80×250mm. S3. The cast billet obtained in step S2 is subjected to rough machining. The billet is rough machined into a tool body of Φ65×220mm using a lathe, and four nozzle channels with a diameter of 4.5±0.1mm are evenly drilled on the end face using a drilling machine. The workpiece to be processed is placed in a vacuum resistance furnace and heated to 1110℃ at a heating rate of 20℃ / min for austenitization and held for 120min. Then, it is quenched with vacuum quenching oil. Next, the quenched workpiece is placed in a vacuum resistance furnace and heated to the tempering temperature of 525℃ and held for 55min. It is then cooled to room temperature in the furnace and the tempering process is repeated three times. The final alloy hardness is 64.5HRC. Finally, the inner wall of the flow channel is finely polished with a diamond grinding wheel for 180s. The polishing medium is 10 vol.% water-based 2.5μm SiO2 suspension, and the inner wall roughness Ra is 0.25μm.

[0052] This embodiment utilizes a high proportion of ferroborone (11.127%), the highest vacuum melting temperature (1580℃), the maximum directional solidification temperature gradient (200K / cm), and the fastest pulling rate (8mm / min), combined with high-temperature austenitization (1110℃) and low-temperature tempering (525℃) processes, to obtain a product with a hardness of 64.5HRC and a surface roughness of 0.25μm. The high boron content and optimized process parameters result in a more dense and ordered arrangement of the (Fe,Cr)2B hard phase, and a sufficiently refined tempered martensitic matrix, exhibiting both extremely high hardness and good toughness. In actual testing, after 1800 hours of service, only slight wear was observed, and the erosion weight loss was only 32mg / 100h, significantly superior to cemented carbide and ordinary carbon steel, making it suitable for high-pressure sand-containing blasting conditions where wear resistance is extremely important.

[0053] Example 2 Water jet tool manufacturing and processing This invention uses electrical pure iron, micro-carbon ferrochrome, ferromolybdenum, ferrotungsten, ferroboron, pig iron, ferrosilicon, and ferromanganese as raw materials. The following components are added respectively: 67.104% electrical pure iron (chemical composition of electrical pure iron: 0.020% C, 0.020% Si, 0.150% Mn, balance Fe), 10.264% micro-carbon ferrochrome (chemical composition of micro-carbon ferrochrome: 0.060% C, 57.000% Cr, 1.450% Si, balance Fe), 2.215% ferromolybdenum (chemical composition of ferromolybdenum: 0.021% C, 0.510% Si, 60.500% Mo, balance Fe), and 4.512% ferrotungsten (chemical composition of ferrotungsten: 0.100% C, 0.500% Si, 80.00% Mn, balance Fe). 0%W, balance Fe), 10.054% ferroboron (ferroboron has a chemical composition of 0.380%C, 0.490%Si, 19.050%B, balance Fe), 5.154% pig iron (pig iron has a chemical composition of 4.270%C, 0.900%Si, 0.113%Mn, balance Fe), 0.096% ferrosilicon (ferrosilicon has a chemical composition of 0.210%C, 72.200%Si, balance Fe), 0.601% ferromanganese (ferrosilicon has a chemical composition of 1.500%C, 1.500%Si, 80.000%Mn, balance Fe).

[0054] The specific preparation process of this invention is as follows: S1. Using electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon as raw materials, vacuum melting is carried out at 1555℃. Then, the molten steel is transferred to a ladle for hot ladle treatment. Boron iron that has been held at 300℃ for 50 minutes is added to the induction furnace. The molten steel in the ladle is then returned to the furnace for remelting. The temperature of the molten steel is raised again to 1520℃ and held for 10 minutes to obtain pure high-boron high-speed steel. S2. Temperature control treatment is applied to the molten steel obtained in step S1. Rare earth aluminum equivalent to 0.012% of the molten steel mass is placed at the bottom of the ladle after the hot ladle treatment. The molten steel is then poured into the ladle for desulfurization treatment. The temperature of the high boron high-speed steel is controlled to decrease to 1380℃ and then transferred to an industrial-grade directional solidification pulling furnace for directional solidification treatment. The solidification interface temperature gradient is 150K / cm, the pulling rate is 5mm / min, and the obtained directional solidification ingot size is Φ80×250mm. S3. The cast billet obtained in step S2 is subjected to rough machining. The billet is rough machined into a tool body of Φ65×220mm using a lathe, and four nozzle channels with a diameter of 4.5±0.1mm are evenly drilled on the end face using a drilling machine. The workpiece to be processed is placed in a vacuum resistance furnace and heated to 1080℃ at a heating rate of 15℃ / min for austenitization and held for 80min. Then, it is quenched with vacuum quenching oil. Next, the quenched workpiece is placed in a vacuum resistance furnace and heated to the tempering temperature of 575℃ and held for 60min. It is then cooled to room temperature in the furnace and the tempering process is repeated three times. The alloy hardness is 60.5HRC. Finally, the inner wall of the flow channel is finely polished with a diamond grinding wheel for 145s. The polishing medium is 10 vol.% water-based 2.5μm SiO2 suspension, and the inner wall roughness Ra is 0.30μm.

[0055] This embodiment employs a moderate component ratio and process parameters: 10.054% ferroboron, vacuum melting temperature of 1555℃, directional solidification temperature gradient of 150K / cm, pulling rate of 5mm / min, austenitizing temperature of 1080℃, tempering temperature of 575℃, product hardness of 60.5HRC, and surface roughness of 0.30μm. This parameter combination achieves an optimal balance between performance and cost, with uniform hard phase arrangement, moderate matrix toughness, and optimal erosion weight loss and service life. It is suitable for most conventional oilfield hydraulic jetting scenarios, balancing reliability and economy, and facilitating large-scale production applications.

[0056] Example 3 Water jet tool manufacturing and processing This invention uses electrical pure iron, micro-carbon ferrochrome, ferromolybdenum, ferrotungsten, ferroboron, pig iron, ferrosilicon, and ferromanganese as raw materials. 70.700% electrical pure iron (with a chemical composition of 0.020% C, 0.020% Si, 0.150% Mn, and the balance being Fe) is added respectively, along with 9.509% micro-carbon ferrochrome (with a chemical composition of 0.060% C, 57.000% Cr, 1.450% Si, and the balance being Fe), 1.736% ferromolybdenum (with a chemical composition of 0.021% C, 0.510% Si, 60.500% Mo, and the balance being Fe), and 4.388% ferrotungsten (with a chemical composition of 0.100% C, 0.500% Si, 80.00% Mn, and the balance being Fe). 0%W, balance Fe), 9.239% ferroboron (ferroboron has a chemical composition of 0.380%C, 0.490%Si, 19.050%B, balance Fe), 3.397% pig iron (pig iron has a chemical composition of 4.270%C, 0.900%Si, 0.113%Mn, balance Fe), 0.481% ferrosilicon (ferrosilicon has a chemical composition of 0.210%C, 72.200%Si, balance Fe), 0.550% ferromanganese (ferrosilicon has a chemical composition of 1.500%C, 1.500%Si, 80.000%Mn, balance Fe).

[0057] The specific preparation process of this invention is as follows: S1. Using electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon as raw materials, vacuum melting is carried out at 1550℃. Then, the molten steel is transferred to a ladle for hot ladle treatment. Boron iron that has been held at 300℃ for 40 minutes is added to the induction furnace. The molten steel in the ladle is then returned to the furnace for remelting. The temperature of the molten steel is raised again to 1500℃ and held for 10 minutes to obtain pure high-boron high-speed steel. S2. Temperature control treatment is applied to the molten steel obtained in step S1. Rare earth aluminum equivalent to 0.012% of the molten steel mass is placed at the bottom of the ladle after the hot ladle treatment. The molten steel is then poured into the ladle for desulfurization treatment. The temperature of the high boron high-speed steel is controlled to decrease to 1400℃ and then transferred to an industrial-grade directional solidification pulling furnace for directional solidification treatment. The solidification interface temperature gradient is 100K / cm, the pulling rate is 3mm / min, and the obtained directional solidification ingot size is Φ80×250mm. S3. The cast billet obtained in step S2 is subjected to rough machining. The billet is rough machined into a tool body of Φ65×220mm using a lathe, and four nozzle channels with a diameter of 4.5±0.1mm are evenly drilled on the end face using a drilling machine. The workpiece to be processed is placed in a vacuum resistance furnace and heated to 1040℃ at a heating rate of 10℃ / min for austenitization and held for 60min. Then, it is quenched with vacuum quenching oil. Next, the quenched workpiece is placed in a vacuum resistance furnace and heated to the tempering temperature of 605℃ and held for 65min. It is then cooled to room temperature in the furnace and the tempering process is repeated three times. The alloy hardness is 58.5HRC. Finally, the inner wall of the flow channel is finely polished with a diamond grinding wheel for 120s. The polishing medium is 10 vol.% water-based 2.5μm SiO2 suspension, and the inner wall roughness Ra is 0.40μm.

[0058] This embodiment uses a low boron-iron content (9.239%) and a lower processing strength, with a vacuum melting temperature of 1550℃, a directional solidification temperature gradient of 100K / cm, a pulling rate of 3mm / min, an austenitizing temperature of 1040℃, and a tempering temperature of 605℃. The product has a hardness of 58.5HRC and a surface roughness of 0.40μm. The lower hardness combined with better toughness can withstand impact loads under complex working conditions and avoid brittle fracture. Although the wear resistance is slightly lower than the previous two embodiments, the production cost is lower, making it suitable for working conditions with small sand particle size and large impact loads, expanding the product's application range and meeting the differentiated needs of different scenarios.

[0059] Example 4 Water jet tool manufacturing and processing This invention uses electrical pure iron, micro-carbon ferrochrome, ferromolybdenum, ferrotungsten, ferroboron, pig iron, ferrosilicon, and ferromanganese as raw materials. The following components are added respectively: 65.320% electrical pure iron (chemical composition of electrical pure iron: 0.020% C, 0.020% Si, 0.150% Mn, balance Fe), 10.850% micro-carbon ferrochrome (chemical composition of micro-carbon ferrochrome: 0.060% C, 57.000% Cr, 1.450% Si, balance Fe), 2.010% ferromolybdenum (chemical composition of ferromolybdenum: 0.021% C, 0.510% Si, 60.500% Mo, balance Fe), and 4.725% ferrotungsten (chemical composition of ferrotungsten: 0.100% C, 0.500% Si, 80.00% Mn, balance Fe). 0%W, balance Fe), 10.580% ferroboron (ferroboron has a chemical composition of 0.380%C, 0.490%Si, 19.050%B, balance Fe), 5.890% pig iron (pig iron has a chemical composition of 4.270%C, 0.900%Si, 0.113%Mn, balance Fe), 0.215% ferrosilicon (ferrosilicon has a chemical composition of 0.210%C, 72.200%Si, balance Fe), 0.610% ferromanganese (ferrosilicon has a chemical composition of 1.500%C, 1.500%Si, 80.000%Mn, balance Fe).

[0060] The specific preparation process of this invention is as follows: S1. Using electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon as raw materials, vacuum melting is carried out at 1565℃. Then, the molten steel is transferred to a ladle for hot ladle treatment. Boron iron that has been held at 300℃ for 55 minutes is added to the induction furnace. The molten steel in the ladle is then returned to the furnace for remelting. The temperature of the molten steel is raised again to 1530℃ and held for 10 minutes to obtain pure high-boron high-speed steel. S2. Temperature control treatment is applied to the molten steel obtained in step S1. Rare earth aluminum equivalent to 0.010% of the molten steel mass is placed at the bottom of the ladle after the hot ladle treatment. The molten steel is then poured into the ladle for desulfurization treatment. The temperature of the high boron high-speed steel is controlled to decrease to 1370℃ and then transferred to an industrial-grade directional solidification pulling furnace for directional solidification treatment. The solidification interface temperature gradient is 180K / cm, the pulling rate is 6mm / min, and the obtained directional solidification ingot size is Φ80×250mm. S3. The cast billet obtained in step S2 is subjected to rough machining. The billet is rough machined into a tool body of Φ65×220mm using a lathe, and four nozzle channels with a diameter of 4.5±0.1mm are evenly drilled on the end face using a drilling machine. The workpiece to be processed is placed in a vacuum resistance furnace and heated to 1095℃ at a heating rate of 18℃ / min for austenitization and held for 100min. Then, it is quenched with vacuum quenching oil. Next, the quenched workpiece is placed in a vacuum resistance furnace and heated to the tempering temperature of 550℃ and held for 62min. It is then cooled to room temperature in the furnace and the tempering process is repeated three times. The alloy hardness is 62.8HRC. Finally, the inner wall of the flow channel is finely polished with a diamond grinding wheel for 160s. The polishing medium is 10 vol.% water-based 2.5μm SiO2 suspension, and the inner wall roughness Ra is 0.28μm.

[0061] This embodiment employs a medium-to-high proportion of ferroboron and a suitable combination of process parameters: ferroboron content 10.580%, vacuum melting temperature 1565℃, directional solidification temperature gradient 180K / cm, and pulling rate 6mm / min. Combined with austenitization at 1095℃ and tempering at 550℃, a precise balance between hardness and toughness is achieved. The directionally arranged (Fe,Cr)₂B hard phase has a moderate density, and the dispersed precipitates in the tempered martensitic matrix are uniformly distributed. This results in a product with a weight loss of only 38mg after 100 hours of erosion under 60MPa high-pressure sand-containing conditions, and a service life exceeding 1700 hours. This embodiment covers the middle-to-optimal range of process parameters in the claims, further verifying the stability of the composition ratio and process parameter combination. It is suitable for conventional oilfield extraction scenarios with high requirements for wear resistance and impact resistance, providing sufficient support for the scope of protection of the claims.

[0062] Example 5 Water jet tool manufacturing and processing This invention uses electrical pure iron, micro-carbon ferrochrome, ferromolybdenum, ferrotungsten, ferroboron, pig iron, ferrosilicon, and ferromanganese as raw materials. The following components are added respectively: 68.950% electrical pure iron (chemical composition of electrical pure iron: 0.020% C, 0.020% Si, 0.150% Mn, balance Fe), 9.980% micro-carbon ferrochrome (chemical composition of micro-carbon ferrochrome: 0.060% C, 57.000% Cr, 1.450% Si, balance Fe), 2.320% ferromolybdenum (chemical composition of ferromolybdenum: 0.021% C, 0.510% Si, 60.500% Mo, balance Fe), and 4.460% ferrotungsten (chemical composition of ferrotungsten: 0.100% C, 0.500% Si, 80.00% Mn, balance Fe). 0%W, balance Fe), 9.870% ferroboron (ferroboron has a chemical composition of 0.380%C, 0.490%Si, 19.050%B, balance Fe), 4.120% pig iron (pig iron has a chemical composition of 4.270%C, 0.900%Si, 0.113%Mn, balance Fe), 0.350% ferrosilicon (ferrosilicon has a chemical composition of 0.210%C, 72.200%Si, balance Fe), 0.650% ferromanganese (ferrosilicon has a chemical composition of 1.500%C, 1.500%Si, 80.000%Mn, balance Fe).

[0063] The specific preparation process of this invention is as follows: S1. Using electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon as raw materials, vacuum melting is carried out at 1570℃. Then, the molten steel is transferred to a ladle for hot ladle treatment. Boron iron that has been held at 300℃ for 45 minutes is added to the induction furnace. The molten steel in the ladle is then returned to the furnace for remelting. The temperature of the molten steel is raised again to 1515℃ and held for 10 minutes to obtain pure high-boron high-speed steel. S2. Temperature control treatment is applied to the molten steel obtained in step S1. Rare earth aluminum equivalent to 0.009% of the molten steel mass is placed at the bottom of the ladle after the hot ladle treatment. The molten steel is then poured into the ladle for desulfurization treatment. The temperature of the high boron high-speed steel is controlled to decrease to 1390℃ and then transferred to an industrial-grade directional solidification pulling furnace for directional solidification treatment. The solidification interface temperature gradient is 120K / cm, the pulling rate is 4mm / min, and the obtained directional solidification ingot size is Φ80×250mm. S3. The cast billet obtained in step S2 is subjected to rough machining. The billet is rough machined into a tool body of Φ65×220mm using a lathe, and four nozzle channels with a diameter of 4.5±0.1mm are evenly drilled on the end face using a drilling machine. The workpiece to be processed is placed in a vacuum resistance furnace and heated to 1060℃ at a heating rate of 12℃ / min for austenitization and held for 75min. Then, it is quenched with vacuum quenching oil. Next, the quenched workpiece is placed in a vacuum resistance furnace and heated to the tempering temperature of 590℃ and held for 58min. It is then cooled to room temperature in the furnace and the tempering process is repeated three times. The alloy hardness is 59.8HRC. Finally, the inner wall of the flow channel is finely polished with a diamond grinding wheel for 135s. The polishing medium is 10 vol.% water-based 2.5μm SiO2 suspension, and the inner wall roughness Ra is 0.35μm.

[0064] This embodiment uses a low to medium proportion of ferroborone and mild process parameters: ferroborone content 9.870%, vacuum melting temperature 1570℃, directional solidification temperature gradient 120K / cm, and pulling rate 4mm / min. Combined with austenitization at 1060℃ and tempering at 590℃, it highlights the product's impact resistance. In the microstructure, the (Fe,Cr)₂B hard phase is uniformly distributed in rod-like shapes, and the tempered martensitic matrix exhibits excellent toughness. Under conditions with large sand particle size (50-80 mesh quartz sand) and large fluctuations in impact load, no cracks were generated after 1500 hours of service, and the erosion weight loss was 45mg / 100h. This embodiment covers the low to medium range of composition and process parameters in the claims, verifying the adaptability of the invention's technical solution under different chemical conditions, further supporting the rationality of the parameter range in the claims, and expanding the application scenarios of the product under complex impact conditions. It also provides more experimental evidence for the process control and performance optimization of high-boron high-speed steel.

[0065] Actual test of hydraulic jetting in oilfield wells Hydraulic jetting tools made of directional solidified high-boron high-speed steel, ordinary carbon steel hydraulic jetting tools, and cemented carbide hydraulic jetting tools were tested in oilfield downhole operations under the following conditions: sand jetting speed: 50 m / s² 3 / h (40~70 mesh quartz sand), water flow velocity: 220m / s, water flow pressure: 60MPa.

[0066] 1. Service life test results: See actual photos of the jetting equipment after service operation testing. Figure 4 .

[0067] Tools made of ordinary carbon steel: After 200 hours of downhole service operation test, the nozzle and pipe wall surface have been damaged, and the oilfield hydraulic jetting tool has lost its service function.

[0068] Example 1: Directional solidification high-boron high-speed steel tool: After 1800 hours of downhole service operation test, the nozzle only showed slight wear, and the oilfield hydraulic jet tool still has service function.

[0069] 2. The wear rate test results of a single nozzle after 100 hours of service are shown in Table 1. The service life of the tool made of directional solidification high boron high-speed steel in Example 1 is 2.7 times that of the traditional cemented carbide tool of the same specification and 13.5 times that of the tool made of different carbon steel.

[0070] Table 1. Comparison of erosion weight loss of a single nozzle after 100 hours of service testing for water jet tools made of different materials.

[0071] Please see Figure 2 The directional solidification direction is perpendicular to the inner wall of the nozzle. With the help of the directional arrangement of (Fe,Cr)2B rod-shaped texture and precipitation-strengthened tempered martensite, it achieves a synergistic effect of resisting abrasive wear under high pressure and high flow rate environment, which significantly reduces the erosion and abrasive wear damage suffered by the inner wall of the nozzle.

[0072] Please see Figure 3 The heat-treated directional solidified high-boron high-speed steel prepared according to the process parameters of Example 1 contains a large number of second-phase precipitated hard particles in its tempered martensitic matrix, and the network eutectic boride skeleton and sharp corners disappear. At this time, the alloy has both hardness and toughness, and has good wear resistance and service safety.

[0073] Please see Figure 4 Under test conditions (sand jetting speed: 50m) 3 The service life of the directionally solidified high-boron high-speed steel tool and the ordinary carbon steel tool in Example 1 were tested by measuring the flow rate (40~70 mesh quartz sand, water flow velocity: 220 m / s, water flow pressure: 60 MPa) for 1800 h. After 1800 h of operation, the nozzle of the directionally solidified high-boron high-speed steel tool in Example 1 showed only slight wear. After 200 h of operation, the ordinary carbon steel tool was severely damaged and lost its service function. This shows that the water jet tool made of the material of the present invention has superior service performance and service life compared with the traditional material tool.

[0074] In summary, this invention provides a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications and its preparation method.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a directional solidification high-boron high-speed steel injection nozzle for oilfield hydraulic applications, characterized in that, Includes the following steps: S1. Using electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon as raw materials, vacuum smelting is carried out to obtain high-boron high-speed steel molten steel. S2. The high-boron high-speed steel molten steel obtained in step S1 is subjected to temperature control treatment, and then transferred to a directional solidification device for directional solidification treatment to obtain a cast billet with directional solidification structure. S3. The as-cast billet obtained in step S2 is subjected to machining, austenitizing quenching and tempering heat treatment in sequence to obtain a directionally solidified high-boron high-speed steel jet nozzle for oilfield hydraulic applications.

2. The method for preparing a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 1, characterized in that, In step S1, the raw materials, by mass fraction, include: 62.069%~70.700% electrical pure iron, 9.509%~11.175% micro-carbon ferrochrome, 4.388%~4.938% ferrotungsten, 1.736%~2.463% ferromolybdenum, 9.239%~11.127% ferroboron, 3.397%~7.405% pig iron, 0.550%~0.700% ferromanganese, and 0.096%~0.481% ferrosilicon.

3. The method for preparing a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 1, characterized in that, In step S1, the vacuum melting specifically includes: First, electrical pure iron, micro-carbon ferrochrome, ferrotungsten, ferromolybdenum, pig iron, ferromanganese, and ferrosilicon are melted into molten steel at 1550~1580℃; The molten steel is transferred to a ladle for hot-scalding treatment. Then, ferroboron that has been held at 300℃ for 40-60 minutes is added and the mixture is remelted in the furnace to raise the temperature of the molten steel to 1500-1540℃ and hold it thereafter to obtain high-boron high-speed steel.

4. The method for preparing a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 1, characterized in that, In step S2, the temperature control process includes: Rare earth aluminum, accounting for 0.008%~0.012% of the steel mass, is added to the molten steel for desulfurization treatment, and the temperature of the molten steel is controlled to drop to 1350~1400℃.

5. The method for preparing a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 1, characterized in that, In step S2, the process parameters for the directional solidification treatment are: The solidification interface temperature gradient is 100~200K / cm, and the pulling rate is 3~8mm / min.

6. The method for preparing a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 1, characterized in that, In step S3, the austenitizing quenching and tempering heat treatment specifically includes: The machined workpiece is heated to 1040-1110℃ under vacuum conditions at a rate of 10-20℃ / min, held for 60-120min, and then oil quenched. The quenched workpiece is tempered under vacuum conditions at a temperature of 525~605℃ for 55~65 minutes. The tempering process is repeated at least 3 times.

7. The method for preparing a directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 1, characterized in that, In step S3, after the tempering heat treatment, the inner wall of the flow channel of the spray nozzle is also subjected to surface polishing treatment. The polishing treatment uses a diamond grinding wheel, the polishing medium is 10 vol.% water-based 2.5 μm SiO2 suspension, and the polishing time is 120~180 s.

8. A directional solidification high-boron high-speed steel injection nozzle for oilfield hydraulic applications, characterized in that, The nozzle is prepared by the preparation method according to any one of claims 1 to 7. The nozzle comprises a metal matrix and a boride hard phase distributed on the matrix. By weight percentage, the alloy composition is C: 0.21%~0.37%, B: 1.76%~2.12%, Cr: 5.42%~6.37%, Mo: 1.05%~1.49%, W: 3.51%~3.95%, Mn: 0.44%~0.56%, Si: 0.40%~0.60%, with the remainder being Fe and unavoidable trace impurities.

9. The directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 8, characterized in that, The hardness of the spray nozzle is 58.5~64.5HRC, and the surface roughness Ra of its inner wall of the flow channel is 0.25~0.40μm; the microstructure of the spray nozzle includes a tempered martensitic matrix and a (Fe,Cr)2B boride hard phase oriented on the matrix.

10. The directional solidification high-boron high-speed steel jet nozzle for oilfield hydraulic applications according to claim 8, characterized in that, The directional solidification direction of the spray nozzle is perpendicular to the direction of the inner wall of the nozzle.

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