A method for preparing low-wettability hard phase particle reinforced high-strength steel

Abstract

The present invention belongs to the technical field of metal material preparation, and specifically relates to a method for preparing high-strength steel reinforced with hard phase particles having low wettability. A combination of gas-solid two-phase flow-assisted jet deposition rapid solidification and high-frequency induction melting technology under high vacuum conditions is adopted. The melting parameters, jet parameters and nozzle layout are precisely controlled to ensure that the molten steel is sprayed in the form of fine droplets, thus avoiding the agglomeration of second-phase particles that occurs in traditional powder metallurgy, casting and other methods. Negative pressure environment spraying is used to reduce defects such as pores on the solidification interface, and the wettability of hard phase particles and molten steel is improved through surface modification technology. The second-phase strengthening particles are dispersed and distributed in the high-strength steel without grain boundary segregation.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material preparation, and in particular relates to a method for preparing low-wettability hard phase particle reinforced high-strength steel. Background Art

[0002] With the rapid development of my country's aerospace, nuclear engineering, and petrochemical industries, there is an increasing demand for materials that can maintain high strength, high oxidation resistance, and high corrosion resistance under extremely high temperature conditions. However, high-strength steels produced by traditional powder metallurgy and casting processes often fail to meet the requirements of use under extreme working conditions after long-term high-temperature service due to problems such as material softening, uneven distribution of second-phase particles, and grain coarsening. Gas-solid two-phase flow, as an efficient mass transfer method, can precisely control the airflow velocity and particle concentration to achieve the positioning and dispersion of solid particles. During the spray deposition process, the high-temperature molten steel liquid converges with the gas-solid two-phase flow, and the inert gas exerts a certain impact and stirring effect on the steel liquid flow, which helps to evenly disperse and refine the steel liquid. At the same time, solid particles are entrained into the steel liquid flow and deposited onto the substrate as the steel liquid is sprayed. The introduction of gas-solid two-phase flow achieves the dispersed distribution of the strengthening phase in the steel liquid, which significantly affects the mechanical properties of the material.

[0003] Based on this, we propose a technique for preparing high-strength steel reinforced with low-wettability hard-phase particles using gas-solid two-phase flow-assisted rapid solidification. This technique cleverly combines the excellent dispersion capabilities of gas-solid two-phase flow with the rapid solidification characteristics of spray deposition, providing a new approach to addressing bottlenecks such as coarsening and uneven distribution of second-phase particles in high-temperature environments. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing low-wettability hard phase particle reinforced high-strength steel.

[0005] The technical solution of the present invention is:

[0006] A method for preparing low-wettability hard phase particle reinforced high-strength steel comprises the following steps:

[0007] Step (1) adopts a double vacuum chamber closed structure device: the double vacuum chamber structure device is divided into a melting chamber, a tundish chamber and a spray deposition chamber, the tundish chamber is connected to the melting chamber and the spray deposition chamber, and the connection and isolation are achieved by a casting plug valve; the melting chamber is provided with a melting ladle, and the liftable tundish is preheated to a temperature outside the chamber and then placed in the tundish chamber; the melting chamber is connected to a high vacuum pump group, and the vacuum degree of the melting chamber is ≤5×10 -2 Pa; the jet deposition chamber is equipped with a high-speed vacuum pump group to maintain the ambient pressure under the jet gas input condition ≤ 5000Pa;

[0008] Step (2) vacuum medium frequency induction melting of the base alloy in a melting chamber, the base alloy being a high alloy steel, including wear-resistant steel, medium manganese steel and die steel, with a typical composition having a medium to high carbon content, and a high level of Mn and Mo segregation components. The typical composition, in terms of mass fraction, comprises C: 0.3-1.2%, Cr: 3-10%, Ni: 0.5-2%, Mn: 0.8-12.5%, Mo: 0.2-1.5%, other microalloying Nb / V / Ti: 0.05-0.5%, N≤10ppm, and the rest being Fe; the melting amount is 1-10t;

[0009] After step (3) and step (2), the superheat of the base alloy solution after smelting is controlled to be +30~80℃, the sealing door of the tundish cabin is closed, the bottom argon blowing deslagging and degassing treatment is carried out by the smelting ladle, the control valve 2 is opened, the pouring gate valve 6 is closed, and then the pouring gate valves of the smelting cabin and the jet deposition cabin are opened, the high-speed vacuum pump group is started, the smelting ladle controls the flow through the bottom slide gate and injects the 304 stainless steel alloy solution into the tundish at a stable liquid level of 110~190mm, and the tundish preheating temperature is ≥1250℃;

[0010] Step (4), surface modification of low-wettability hard phase particles: low-wettability hard phase particles include SiC, Fe3C, corundum and graphite particles, the low-wettability hard phase particles are ball-milled and mixed with low-carbon steel, Fe or Al powder in liquid argon, and the mass fraction of low-wettability hard phase particles is more than 95%; wherein, the particle size of the low-wettability hard phase particles is less than 2.5 μm, the particle size of the metal powder is 25-35 μm, the ball milling time is more than 20 hours, the ball milling speed is 280-320 r / min, the metal powder is promoted to adhere to the surface of the low-wettability hard phase particles, and the low-wettability hard phase particles and the matrix alloy solution are fully wetted, wherein the particles provide a solidification heat transfer ratio of more than 30%;

[0011] Step (5), the low-wettability hard phase particles after surface modification in step (4) are mixed uniformly with the inert gas Ar in a gas-solid two-phase flow mixing and preheating device and preheated to form a gas-solid two-phase flow, and are divided into two routes to enter the injection mechanism through the two-phase flow pipeline, the matrix alloy solution is ejected through the injection mechanism, and the inert gas Ar blows the low-wettability hard phase particles into the matrix alloy solution being ejected through the two-phase flow pipeline, and the two converge and are deposited on the deposition blank;

[0012] Step (6), the gas-solid two-phase flow fully disperses the matrix alloy solution flowing out of the two pouring ingots of the injection mechanism into uniform droplets in the injection deposition chamber, and completes the deposition blank injection on the deposition plate;

[0013] After step (7), the top temperature of the ingot is controlled to be ≤1300℃ and the bottom temperature of the ingot is controlled to be ≤1200℃. After the ingot is taken out, it is sent to a 1180℃ forging and holding furnace for 2 hours, and then forged into a square billet for hot rolling. The final rolling thickness is 3.0~30mm.

[0014] Furthermore, in the above-mentioned method for preparing a low-wettability hard phase particle reinforced high-strength steel, the number of pores counted on the solidification end surface in the spray deposition chamber is ≤4 / 10mm 2 , and the pore size is ≤1.5μm, and all the pores are pressed together after forging in step (7).

[0015] Furthermore, in the above-mentioned method for preparing a high-strength steel reinforced with low-wettability hard phase particles, after hot rolling in step (7), the mass fraction of low-wettability hard phase particles in the hot-rolled plate matrix is ​​more than 1%, the size of the low-wettability hard phase particles is controlled to be 800~3000nm, and they are evenly distributed on the matrix, without grain boundary segregation phenomenon, and without shrinkage cavity phenomenon around the second phase. The wear resistance life of the reinforced particles is increased by more than 30%, the macro hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by ≤1% compared with the non-second phase reinforced matrix.

[0016] Furthermore, in the above-mentioned method for preparing high-strength steel reinforced with low-wettability hard phase particles, the preheating temperature of the surface-modified low-wettability hard phase particles in step (5) is ≥650°C, and the powder feeding rate of the low-wettability hard phase particles with a particle size of 500~3000nm is 320~1200g / min.

[0017] Furthermore, in the above-mentioned method for preparing a low-wettability hard phase particle reinforced high-strength steel, in step (1), two nozzles are horizontally arranged at the lower edge of the tundish, the nozzle diameter is φ4~10mm, the single nozzle flow rate is 25~65kg / min, the nozzle outlet flow rate is 1.2~2.0m / min, the nozzle position is opposite to the 1 / 3 and 2 / 3 positions of the deposited billet radius, and the outer nozzle aperture area is 25% larger than the inner nozzle aperture.

[0018] Furthermore, in the above-mentioned method for preparing a low-wettability hard phase particle reinforced high-strength steel, in step (5), the number of openings of the spray deposition ring of the spray mechanism is 10 to 218, the aperture is 4 to 10 mm, and the focal length is 50 to 80 mm below the normal plane; the spray deposition ring is made of heat-resistant stainless steel, and the inner surface is plated with hard chromium, HRC52 or above; the inclination angle of the spray deposition ring is -25 to +35°, and the scanning frequency is 0 to 3 Hz; the gas injection pressure is 0.5 to 0.857 MPa, and the injection volume of a single spray deposition ring is 10 to 40 m 3 / min.

[0019] Furthermore, in the above-mentioned method for preparing a low-wettability hard phase particle reinforced high-strength steel, during the spray deposition process in step (6), the distance between the deposition disk and the lower end of the spray deposition ring is controlled to be 180~500mm, the diameter of the deposition billet is 300~600mm, the rotation speed of the deposition disk is 30~90r / min, the descending speed is 60~120mm / min, and the surface molten pool depth is controlled to be 1~2.5mm.

[0020] Advantages and beneficial effects of the present invention:

[0021] 1. The present invention utilizes gas-solid two-phase flow technology for precise control, accurately injecting size-controlled second-phase particles into the molten steel, avoiding agglomeration and significantly improving the strengthening effect;

[0022] 2. The present invention combines rapid solidification technology with spray deposition to rapidly cool the molten steel, achieve dislocation pinning by second-phase particles, and refine grains, thereby improving the comprehensive mechanical properties of the steel and meeting application requirements under extreme working conditions.

[0023] 3. The present invention selects second-phase particles such as SiC or corundum, which are stable at high temperatures and have significant strengthening effects. These particles can maintain stable physical and chemical properties in high-temperature environments, providing a long-lasting strengthening effect for high-strength steel.

[0024] 4. The present invention performs injection molding completely in a vacuum environment, and the deposition process reduces oxidation and contamination of materials, thereby reducing subsequent processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the process for preparing low-wettability hard phase particle reinforced high-strength steel according to the present invention;

[0026] In the figure: 1- high vacuum pump group; 2- control valve a; 3- melting chamber; 4- melting ladle; 5- tundish; 6- pouring gate valve; 7- tundish chamber sealing door; 8- tundish chamber; 9- gas-solid two-phase flow mixing and preheating device; 10- two-phase flow pipeline; 11- injection mechanism; 12- injection deposition chamber; 13- deposition blank; 14- deposition plate; 15- control valve b; 16- solid phase particle cyclone separator; 17- control valve c; 18- high pumping speed vacuum pump group. DETAILED DESCRIPTION

[0027] The schematic diagram of the process for preparing low-wettability hard phase particle reinforced high-strength steel of the present invention is as follows: Figure 1 As shown, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention but cannot be used to limit the scope of the present invention.

[0028] In the following embodiments, a double vacuum chamber closed structure is used to achieve negative pressure environment spraying: the double vacuum chamber structure is divided into a melting chamber 3, a tundish chamber 8 and a spray deposition chamber 12. The tundish chamber 8 connects the melting chamber 3 and the spray deposition chamber 12, and is connected and isolated by a casting gate valve 6; the melting chamber 3 is provided with a melting ladle 4, and the liftable tundish 5 is preheated to temperature outside the chamber and then placed in the tundish chamber 8; the melting chamber 3 is connected to the high vacuum pump group 1, and the spray deposition chamber 12 is independently provided with a high-speed vacuum pump group 18. Example 1

[0029] In this embodiment, a method for preparing low-wettability hard phase particle reinforced high-strength steel includes the following steps:

[0030] Step (1) Open the control valve a2, close the pouring plate valve 6, and adjust the vacuum degree of the melting chamber 3 to ≤5×10 -2 Pa, maintaining the ambient pressure under the injection gas input condition ≤ 5000Pa; two nozzles are arranged horizontally on the lower edge of the tundish 5, with a nozzle diameter of φ4mm, a single nozzle flow rate of 20kg / min, and a nozzle outlet flow rate of 1.0m / min. The nozzle position is directly opposite to the 1 / 3 and 2 / 3 positions of the deposited billet radius, and the outer nozzle aperture area is 20% larger than the inner nozzle aperture;

[0031] Step (2) vacuum medium frequency induction melting of manganese steel in the melting chamber 3, wherein the manganese steel composition is: C: 0.3%, Cr: 3%, Ni: 0.5%, Mn: 0.8%, Mo: 0.2%, other microalloying Nb / V / Ti: 0.05%, N ≤ 10ppm, and the rest is Fe; the melting amount is 2t;

[0032] Step (3) After the smelting of step (2), the superheat of the manganese steel solution is controlled to be +30°C, and the smelting ladle 4 is used for bottom argon blowing and deslagging and degassing treatment. The control valve a2 and the tundish cabin sealing door 7 are closed, and then the control valve b15 and the control valve c17 are opened. Then, the pouring plug valve 6 of the smelting cabin 3 and the spray deposition cabin 12 is opened, and the high-speed vacuum pump group 18 is started. The smelting ladle 4 controls the flow through the bottom slide water inlet and injects the 304 stainless steel alloy solution into the tundish to stabilize the liquid level at 100mm. The tundish 5 is preheated to 1200°C.

[0033] Step (4) Surface modification of low-wettability hard phase particles: low-wettability hard phase SiC particles are mixed with low-carbon steel by ball milling in liquid argon, with the mass fraction of low-wettability hard phase particles being 95%; wherein, the particle size of the low-wettability hard phase SiC particles is 2 μm, the particle size of the low-wettability hard phase particles is 2 μm, and the ball milling time is 24 hours, to promote the attachment of metal powder to the surface of the low-wettability hard phase particles and to promote the sufficient wetting of the low-wettability hard phase particles and the manganese steel solution, wherein the particles provide 30% of the solidification heat transfer ratio;

[0034] Step (5) The low-wettability hard phase particles after surface modification in step (4) are mixed evenly with the inert gas Ar in the gas-solid two-phase flow mixing and preheating device 9 and preheated to form a gas-solid two-phase flow, and are divided into two routes to enter the injection mechanism 11 through the two-phase flow pipe 10. The manganese steel solution is ejected through the injection mechanism 11, and the inert gas Ar blows the low-wettability hard phase particles through the two-phase flow pipe 10 into the manganese steel solution being ejected. The two converge and are deposited on the deposition blank 13; the preheating temperature of the surface-modified low-wettability hard phase particles is 600°C, and the 500nm particle size is 0. The powder feeding rate of the low-wettability hard phase particles is 500g / min; the nozzle of the injection mechanism 11 is adjusted to the center of the injection deposition ring, the center line is aligned, and the lower plane is parallel to the lower plane of the injection deposition ring. The number of openings in the injection deposition ring is 12, the aperture is 4mm, and the focal length is 60mm below the normal plane; the injection deposition ring is made of heat-resistant stainless steel, the inner surface is plated with hard chrome, HRC52 or above; the injection deposition ring inclination angle is -30~+30°, the scanning frequency is 1Hz; the gas injection pressure is 0.5MPa, and the injection volume of a single injection deposition ring is 15m 3 / min;

[0035] Step (6) The gas-solid two-phase flow fully disperses the manganese steel solution flowing out of the two pouring ingots of the injection mechanism 11 into uniform droplets in the injection deposition chamber 12, and completes the injection of the deposition blank 13 on the deposition plate 14; during the injection deposition process, the deposition plate 14 is controlled to be 200 mm away from the lower end of the injection deposition ring, the diameter of the deposition blank 13 is 400 mm, the rotation speed of the deposition plate is 40 r / min, the descending speed is 50 mm / min, and the surface molten pool depth is controlled to be 1 mm;

[0036] After step (7) spraying is completed, the top temperature of the ingot is controlled at 1350°C and the bottom temperature of the ingot is controlled at 1250°C. After the ingot is taken out, it is sent to a 1180°C forging and holding furnace for 2 hours, and then forged into a square billet for hot rolling. The final rolling thickness is 3.0 mm. The mass fraction of low-wettability hard phase particles in the hot-rolled plate matrix is ​​1%, and the size of the low-wettability hard phase particles is controlled at 800 nm. They are evenly distributed on the matrix without grain boundary segregation. The wear resistance of the reinforced particles is increased by more than 30%, the macro hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by ≤1% compared with the non-second phase reinforced matrix.

[0037] The number of pores on the solidification end surface in the spray deposition chamber 12 is 4 / 10mm. 2 , and the pore size is 1.5μm. After forging in step (7), all the pores are pressed together. Example 2

[0038] In this embodiment, a method for preparing low-wettability hard phase particle reinforced high-strength steel includes the following steps:

[0039] Step (1) Open the control valve a2, close the pouring plate valve 6, and adjust the vacuum degree of the melting chamber 3 to ≤5×10 -2 Pa, maintain the ambient pressure under the injection gas input condition ≤ 5000Pa; two nozzles are arranged horizontally on the lower edge of the tundish 5, with a nozzle diameter of φ7mm, a single nozzle flow rate of 40kg / min, and a nozzle outlet flow rate of 1.4m / min. The nozzle position is directly opposite to the 1 / 3 and 2 / 3 positions of the deposited billet radius, and the outer nozzle aperture area is 20% larger than the inner nozzle aperture;

[0040] Step (2) vacuum medium frequency induction melting of manganese steel in the melting chamber 3, wherein the manganese steel composition is: C: 0.8%, Cr: 5%, Ni: 1%, Mn: 6.5%, Mo: 1%, other microalloying Nb / V / Ti: 0.25%, N ≤ 10ppm, and the rest is Fe; the melting amount is 3t;

[0041] Step (3) After the smelting of step (2), the superheat of the medium manganese steel solution is controlled to be +55°C, and the smelting ladle 4 is used for bottom argon blowing and deslagging and degassing treatment. The control valve a2 and the tundish cabin sealing door 7 are closed, and then the control valve b15 and the control valve c17 are opened. Then, the pouring plug valve 6 of the smelting cabin 3 and the spray deposition cabin 12 is opened, and the high-speed vacuum pump group 18 is started. The smelting ladle 4 controls the flow through the bottom slide water inlet and injects the 304 stainless steel alloy solution into the tundish to stabilize the liquid level at 150mm. The preheating temperature of the tundish 5 is ≥1300°C.

[0042] Step (4) Surface modification of low-wettability hard phase particles: SiC particles are selected as low-wettability hard phase particles, and the SiC particles are ball-milled with medium manganese steel powder in liquid argon to obtain a mass fraction of low-wettability hard phase particles of 96%; wherein, the particle size of the SiC particles is 2 μm, the particle size of the SiC particles is 1.8 μm, and the ball milling time is 30 hours, to promote the adhesion of metal powder to the surface of the SiC particles and to promote the full wetting of the SiC particles and the manganese steel solution, wherein the particles provide 30% of the solidification heat transfer ratio;

[0043] Step (5) The SiC particles after surface modification in step (4) are mixed uniformly with the inert gas Ar in the gas-solid two-phase flow mixing and preheating device 9 and preheated to form a gas-solid two-phase flow, and are divided into two routes to enter the injection mechanism 11 through the two-phase flow pipe 10. The manganese steel solution is ejected through the injection mechanism 11, and the inert gas Ar blows the B4C particles into the manganese steel solution in the injection through the two-phase flow pipe 10. The two converge and are deposited on the deposition blank 13; the preheating temperature of the surface modified SiC particles is 700°C, and the particle size is 1500nm. The SiC particle feeding rate is 750g / min; the nozzle of the injection mechanism 11 is adjusted to the center of the injection deposition ring, the center line is aligned, and its lower plane is parallel to the lower plane of the injection deposition ring. The injection deposition ring has 16 openings with an aperture of 6mm and a focal length of 70mm below the normal plane; the injection deposition ring is made of heat-resistant stainless steel, with an inner surface plated with hard chrome, HRC52 or above; the injection deposition ring has an inclination angle of -0° and a scanning frequency of 1Hz; the gas injection pressure is 0.65MPa, and the injection volume of a single injection deposition ring is 30m 3 / min;

[0044] Step (6) The gas-solid two-phase flow fully disperses the manganese steel solution flowing out of the two pouring ingots of the injection mechanism 11 into uniform droplets in the injection deposition chamber 12, and completes the injection of the deposition blank 13 on the deposition plate 14; during the injection deposition process, the deposition plate 14 is controlled to be 325 mm away from the lower end of the injection deposition ring, the diameter of the deposition blank 13 is 450 mm, the rotation speed of the deposition plate is 60 r / min, the descending speed is 85 mm / min, and the surface molten pool depth is controlled to be 1-2 mm;

[0045] After step (7) spraying is completed, the top temperature of the ingot is controlled at 1250°C and the bottom temperature of the ingot is controlled at 1150°C. After the ingot is taken out, it is sent to a 1180°C forging and holding furnace for 2 hours, and then forged into a square billet for hot rolling. The final rolling thickness is 10 mm. The mass fraction of SiC particles in the hot-rolled plate matrix is ​​1%, and the SiC particle size is controlled at 1500 nm. It is evenly distributed on the matrix without grain boundary segregation. The SiC particles enhance the wear resistance life by more than 30%, the macro hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by ≤1% compared with the non-second phase strengthened matrix.

[0046] The number of pores on the solidification end surface in the spray deposition chamber 12 is 4 / 10mm. 2 , and the pore size is 0.8μm. After forging in step (7), all the pores are pressed together. Example 3

[0047] In this embodiment, a method for preparing low-wettability hard phase particle reinforced high-strength steel includes the following steps:

[0048] Step (1) Open the control valve a2, close the pouring plate valve 6, and adjust the vacuum degree of the melting chamber 3 to ≤5×10 -2 Pa, maintaining the ambient pressure under the injection gas input condition ≤ 5000Pa; two nozzles are arranged horizontally on the lower edge of the tundish 5, with a nozzle diameter of φ10mm, a single nozzle flow rate of 60kg / min, and a nozzle outlet flow rate of 1.8m / min. The nozzle position is directly opposite to the 1 / 3 and 2 / 3 positions of the deposited billet radius, and the outer nozzle aperture area is 20% larger than the inner nozzle aperture;

[0049] Step (2) vacuum medium frequency induction melting of mold steel in the melting chamber 3, wherein the mold steel composition is: C: 1.2%, Cr: 10%, Ni: 2%, Mn: 12.5%, Mo: 1.5%, other microalloying Nb / V / Ti: 0.5%, N ≤ 10ppm, and the rest is Fe; the melting amount is 6t;

[0050] Step (3) After the smelting of step (2), the mold steel solution is controlled to be superheated at +80°C, and the bottom argon blowing deslagging and degassing treatment is carried out by the melting ladle 4. The control valve a2 and the tundish cabin sealing door 7 are closed, and then the control valve b15 and the control valve c17 are opened. Then, the pouring plug valve 6 of the melting cabin 3 and the spray deposition cabin 12 is opened, and the high-speed vacuum pump group 18 is started. The melting ladle 4 controls the flow through the bottom slide water inlet and injects the 304 stainless steel alloy solution into the tundish to stabilize the liquid level at 180 mm. The tundish 5 is preheated to 1400°C.

[0051] Step (4) Surface modification of low-wettability hard phase particles: Fe3C particles are selected as low-wettability hard phase particles, and the Fe3C particles are ball-milled with low-carbon steel in liquid argon, with a mass fraction of SiC particles of 98%; wherein, the Fe3C particle size is 2 μm, the Fe3C particle size is less than 1.5 μm, and the ball milling time is more than 35 hours, to promote the adhesion of metal powder to the surface of the Fe3C particles and promote the full wetting of the Fe3C particles and the manganese steel solution, wherein the particles provide 30% of the solidification heat transfer ratio;

[0052] Step (5) The Fe3C particles after surface modification in step (4) are mixed uniformly with the inert gas Ar in the gas-solid two-phase flow mixing and preheating device 9 and preheated to form a gas-solid two-phase flow, and are divided into two routes to enter the injection mechanism 11 through the two-phase flow pipe 10. The manganese steel solution is ejected through the injection mechanism 11, and the inert gas Ar blows the Fe3C particles through the two-phase flow pipe 10 into the manganese steel solution being ejected. The two converge and are deposited on the deposition blank 13; the preheating temperature of the surface modified Fe3C particles is 620°C, and the particle size is 3000nm. The Fe3C particle feeding rate is 1250g / min; the nozzle of the injection mechanism 11 is adjusted to the center of the injection deposition ring, the center line is aligned, and its lower plane is parallel to the lower plane of the injection deposition ring. The injection deposition ring has 20 openings with an aperture of 8mm and a focal length of 80mm below the normal plane; the injection deposition ring is made of heat-resistant stainless steel, with an inner surface plated with hard chrome, HRC52 or above; the injection deposition ring has an inclination angle of +30° and a scanning frequency of 2Hz; the gas injection pressure is 0.85MPa, and the injection volume of a single injection deposition ring is 45m 3 / min;

[0053] Step (6) The gas-solid two-phase flow fully disperses the manganese steel solution flowing out of the two pouring ingots of the injection mechanism 11 into uniform droplets in the injection deposition chamber 12, and completes the injection of the deposition blank 13 on the deposition plate 14; during the injection deposition process, the deposition plate 14 is controlled to be 450 mm away from the lower end of the injection deposition ring, the diameter of the deposition blank 13 is 500 mm, the rotation speed of the deposition plate is 80 r / min, the descending speed is 120 mm / min, and the surface molten pool depth is controlled to be 2 mm;

[0054] After step (7) spraying is completed, the top temperature of the ingot is controlled at 1280°C and the bottom temperature of the ingot is controlled at 1180°C. After the ingot is taken out, it is sent to a 1180°C forging and holding furnace for 2 hours, and then forged into a square billet for hot rolling. The final rolling thickness is 15 mm. The mass fraction of Fe3C particles in the hot-rolled plate matrix is ​​1%, and the Fe3C particle size is controlled at 1500 nm. It is evenly distributed on the matrix without grain boundary segregation. The Fe3C particles enhance the wear life by more than 30%, the macro hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by ≤1% compared with the non-second phase strengthened matrix.

[0055] The number of pores on the solidification end surface in the spray deposition chamber 12 is 4 / 10mm. 2 , and the pore size is ≤1.2μm, and all the pores are pressed together after forging in step (7). Example 4

[0056] The difference between this embodiment and embodiment 1 is that:

[0057] (1) The low-wettability hard phase particles are corundum particles. The corundum particles and low-carbon steel are subjected to low-temperature ball milling to modify the surface, promote the attachment of low-carbon steel powder to the surface of the corundum particles, and improve the wettability of the solid phase particles and the steel liquid. The particle size of the reinforcement particles is less than 2μm, and the metal powder is 20-30μm. The ball milling is carried out for 50 hours.

[0058] (2) The diamond powder and the low carbon steel powder are ball milled and stirred evenly for 24 hours at a ball mill speed of 280 r / min;

[0059] (3) After the ingot is sprayed, it is forged into a square billet for hot rolling, with a final rolling thickness of 20 mm;

[0060] (4) The jet deposition ring is equipped with 20 holes. Example 5

[0061] The difference between this embodiment and embodiment 2 is that:

[0062] (1) The low-wettability hard phase particles are graphite particles. The graphite particles are subjected to low-temperature ball milling with Fe to modify the surface, promote the attachment of low-carbon steel powder to the surface of the diamond particles, and improve the wettability of the solid phase particles and the steel liquid. The particle size of the reinforcement particles is less than 2μm, the metal powder is 20-30μm, and the ball milling is carried out for 50 hours;

[0063] (2) The graphite sand powder and the low carbon steel powder are ball milled and stirred evenly for 24 hours at a ball mill speed of 280 r / min;

[0064] (3) After the ingot is sprayed, it is forged into a square billet for hot rolling, with a final rolling thickness of 30 mm;

[0065] (4) The jet deposition ring is equipped with 20 holes. Example 6

[0066] The difference between this embodiment and embodiment 3 is that:

[0067] (1) The low-wettability hard phase particles are graphite particles. The graphite particles and Al alloy are subjected to low-temperature ball milling for surface modification, which promotes the attachment of low-carbon steel powder to the surface of the diamond particles and improves the wettability of the solid phase particles and the steel liquid. The particle size of the reinforcement particles is less than 2μm, and the metal powder is 20-30μm. The ball milling is carried out for 50 hours.

[0068] (2) The graphite sand powder and the Al alloy powder are ball-milled and stirred to mix evenly. The ball-milling process is repeated in the following modes: ball milling for 2 hours, pausing for 15 minutes; ball milling for 1 hour, pausing for 10 minutes; and then ball milling for 1 hour, pausing for 5 minutes.

[0069] (3) After the ingot is sprayed, it is forged into a square billet for hot rolling, with a final rolling thickness of 10 mm;

[0070] (4) The jet deposition ring is equipped with 20 holes.

[0071] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing low-wettability hard phase particle reinforced high-strength steel, characterized in that: The following steps are involved: Step (1) adopting a double vacuum chamber closed structure device: the double vacuum chamber structure device is divided into a melting chamber, a tundish chamber and a spray deposition chamber, the tundish chamber is connected to the melting chamber and the spray deposition chamber, and the connection and isolation are achieved by a casting plug valve; the melting chamber is provided with a melting ladle, and the liftable tundish is preheated to temperature outside the chamber and then placed in the tundish chamber; The smelting chamber is connected to a high vacuum pump group, and the vacuum degree of the smelting chamber is ≤5×10 -2 Pa; the jet deposition chamber is equipped with a high-speed vacuum pump group to maintain the ambient pressure under the jet gas input condition ≤ 5000Pa; Step (2) vacuum medium frequency induction melting of the base alloy in a melting chamber, the base alloy being a high alloy steel, including wear-resistant steel, medium manganese steel or die steel, with a typical composition having a medium to high carbon content, and a high level of Mn and Mo segregation components, wherein the typical composition, by mass fraction, comprises C: 0.3-1.2%, Cr: 3-10%, Ni: 0.5-2%, Mn: 0.8-12.5%, Mo: 0.2-1.5%, other microalloying Nb / V / Ti: 0.05-0.5%, N≤10ppm, and the remainder being Fe; the melting amount is 1-10t; In step (3) and step (2), the superheat of the base alloy solution after smelting is controlled to be +30~80℃, the sealing door of the tundish cabin is closed, the bottom argon blowing deslagging and degassing treatment is carried out by the smelting ladle, the control valve 2 is opened, the pouring gate valve 6 is closed, and then the pouring gate valves of the smelting cabin and the spray deposition cabin are opened, the high-speed vacuum pump group is started, the smelting ladle controls the flow through the bottom slide water inlet and injects the smelted molten steel into the tundish at a stable liquid level of 110~190mm, and the tundish preheating temperature is ≥1250℃; Step (4), surface modification of low-wettability hard phase particles: low-wettability hard phase particles include SiC, Fe3C, corundum or graphite particles, and the low-wettability hard phase particles are ball-milled with low-carbon steel, Fe or Al powder in liquid argon, with the mass fraction of low-wettability hard phase particles being more than 95%; wherein, the particle size of the low-wettability hard phase particles is less than 2.5 μm, the particle size of the metal powder is 25-35 μm, the ball milling time is more than 20 hours, the ball milling speed is 280-320 r / min, the metal powder is promoted to adhere to the surface of the low-wettability hard phase particles, and the low-wettability hard phase particles and the matrix alloy solution are fully wetted, wherein the particles provide a solidification heat transfer ratio of more than 30%; Step (5), the low-wettability hard phase particles after surface modification in step (4) are mixed uniformly with the inert gas Ar in a gas-solid two-phase flow mixing and preheating device and preheated to form a gas-solid two-phase flow, and are divided into two routes to enter the injection mechanism through the two-phase flow pipeline, the matrix alloy solution is ejected through the injection mechanism, and the inert gas Ar blows the low-wettability hard phase particles into the matrix alloy solution being ejected through the two-phase flow pipeline, and the two converge and are deposited on the deposition blank; Step (6), the gas-solid two-phase flow fully disperses the matrix alloy solution flowing out of the two pouring ingots of the injection mechanism into uniform droplets in the injection deposition chamber, and completes the deposition blank injection on the deposition plate; After step (7), the top temperature of the ingot is controlled to be ≤1300℃ and the bottom temperature of the ingot is controlled to be ≤1200℃. After the ingot is taken out, it is sent to a 1180℃ forging and holding furnace for 2 hours, and then forged into a square billet for hot rolling. The final rolling thickness is 3.0~30mm.

2. The method for preparing a low-wettability hard phase particle reinforced high-strength steel according to claim 1, characterized in that: The number of pores on the solidification end surface in the spray deposition chamber is ≤4 / 10mm 2 , and the pore size is ≤1.5μm, and all the pores are pressed together after forging in step (7).

3. The method for preparing a low-wettability hard phase particle reinforced high-strength steel according to claim 1, characterized in that: After hot rolling in step (7), the mass fraction of low-wettability hard phase particles in the hot-rolled plate matrix is ​​more than 1%, the size of the low-wettability hard phase particles is controlled to be 800-3000 nm, and they are evenly distributed on the matrix without grain boundary segregation and shrinkage cavities around the second phase.

4. The method for preparing a low-wettability hard phase particle reinforced high-strength steel according to claim 1, characterized in that: The preheating temperature of the surface-modified low-wettability hard phase particles in step (5) is ≥650°C, and the powder feeding rate of the low-wettability hard phase particles with a particle size of 500~3000nm is 320~1200g / min.

5. The method for preparing low-wettability hard phase particle reinforced high-strength steel according to claim 1, characterized in that: In step (1), two nozzles are arranged horizontally at the lower edge of the tundish, with a nozzle diameter of φ4~10mm, a single nozzle flow rate of 25~65kg / min, a nozzle outlet flow rate of 1.2~2.0m / min, and the nozzle position is opposite to the 1 / 3 and 2 / 3 positions of the deposited billet radius. The outer nozzle aperture area is 25% larger than the inner nozzle aperture.

6. The method for preparing low-wettability hard phase particle reinforced high-strength steel according to claim 1, characterized in that: The number of openings of the spray deposition ring of the spray mechanism in step (5) is 10 to 218, the aperture is 4 to 10 mm, and the focal length is 50 to 80 mm below the normal plane; the spray deposition ring is made of heat-resistant stainless steel, and the inner surface is plated with hard chrome, HRC52 or above; the spray deposition ring inclination angle is -25 to +35°, and the scanning frequency is 0 to 3 Hz; the gas injection pressure is 0.5 to 0.857 MPa, and the injection volume of a single spray deposition ring is 10 to 40 m 3 / min.

7. The method for preparing low-wettability hard phase particle reinforced high-strength steel according to claim 1, characterized in that: During the spray deposition process in step (6), the distance between the deposition disk and the lower end of the spray deposition ring is controlled to be 180~500mm, the diameter of the deposition billet is 300~600mm, the rotation speed of the deposition disk is 30~90r / min, the descending speed is 60~120mm / min, and the surface molten pool depth is controlled to be 1~2.5mm.

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