Ultrahigh strength and toughness gearbox valve body, powder core wire for gearbox valve body and method

Abstract

The application discloses a powder core wire for a gearbox valve body with super high strength and toughness, which comprises a powder core and a sheath. The powder core is composed of the following powders in percentage by mass: carbon powder 0.5%, manganese powder 10%-15%, chromium powder 10%-15%, nickel powder 15-20%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%-2%, and iron powder in the rest. The sheath is a low-carbon steel belt. The filling rate of the powder core wire is 20wt%-25wt%. The powder core wire is used for 3D printing to manufacture a super high strength and toughness structural member. The application also discloses a gearbox valve body with super high strength and toughness, a preparation method of the powder core wire for the gearbox valve body with super high strength and toughness, and a preparation method of the gearbox valve body with super high strength and toughness.

Description

Technical Field

[0001] This invention belongs to the field of intelligent manufacturing, specifically relating to a powder core wire for an ultra-high strength and toughness transmission valve body and an ultra-high strength and toughness transmission valve body, as well as a method for preparing the powder core wire for an ultra-high strength and toughness transmission valve body and a method for preparing the ultra-high strength and toughness transmission valve body. Background Technology

[0002] Due to its excellent properties such as high strength and high toughness, ultra-high strength and toughness steel has been widely chosen as the preferred material for key components in metallurgy, automotive, and aerospace industries for many years. It is also widely used in many important industrial fields such as metallurgy, military, engineering, power, and aviation.

[0003] The transmission valve body mainly controls the clutch and shift fork through hydraulic principles. Automotive transmission valve bodies are usually made of ultra-high strength and toughness materials. However, investigations have found that the production technology and quality control of this type of ultra-high strength and toughness steel in China are currently unstable. The transmission valve body is manufactured using die casting technology, resulting in inconsistent thicknesses in different parts. Defects such as porosity, slag holes, and sand holes may occur during the casting process, which seriously limits the service life.

[0004] Currently, most gearbox valve bodies are manufactured using a casting-forging-finishing process. This method not only results in high material waste and inconsistent casting quality, but also leads to long production cycles and numerous steps. Casting such complex parts is difficult to control for uniform cooling, which can cause macroscopic segregation and cracking. Furthermore, forging this high-strength steel is extremely difficult to machine and can easily damage cutting tools. Summary of the Invention

[0005] The first objective of this invention is to provide a powder core filament for an ultra-high strength and toughness gearbox valve body, which is used for 3D printing to manufacture ultra-high strength and toughness structural parts.

[0006] The second objective of this invention is to provide a method for preparing powder core wire for ultra-high strength and toughness gearbox valve bodies.

[0007] The third objective of this invention is to provide a method for preparing an ultra-high strength and toughness transmission valve body. The mechanical properties of the ultra-high strength and toughness transmission valve body manufactured by this method meet the actual working conditions, while avoiding the problems of difficulty in hardening and cracking that occur in the traditional manufacturing of ultra-high strength and toughness transmission valve bodies.

[0008] The fourth objective of this invention is to provide an ultra-high strength and toughness gearbox valve body.

[0009] The first technical solution adopted in this invention is a powder core wire for an ultra-high strength and toughness gearbox valve body, comprising a core powder and an outer sheath. The core powder is composed of the following powders by mass percentage: carbon powder 0.5%, manganese powder 10%–15%, chromium powder 10%–15%, nickel powder 15–20%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%–2%, and iron powder balance, with the sum of the above components by mass percentage being 100%. The outer sheath is a low-carbon steel strip, specifically composed of C: 0.021%; Mn: 0.15%; S: 0.006%; P: 0.007%; Si: 0.19%; Fe: balance. The filling rate of the powder core wire is 20wt%–25wt%.

[0010] The second technical solution adopted in this invention is a method for preparing ultra-high strength and toughness powder core wire for gearbox valve bodies, specifically as follows:

[0011] Step 1: Weigh the following core powders according to their mass percentages: carbon powder 0.5%, manganese powder 10%–15%, chromium powder 10%–15%, nickel powder 15%–20%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%–2%, and iron powder balance. The sum of the mass percentages of the above components is 100%.

[0012] Step 2: All weighed powders are first alloyed using a planetary ball mill at a speed of 300-350 r / min for 4-5 hours. Then, flux-cored wires are prepared using a metal flux-cored wire drawing machine. The diameter of the flux-cored wire is reduced every 0.2 mm until it reaches a diameter of 1.6 mm. The outer sheath is made of low-carbon steel strip with the following composition: C: 0.021%; Mn: 0.15%; S: 0.006%; P: 0.007%; Si: 0.19%; Fe: balance. The filling rate of the powder-cored wire is 20wt%-25wt%.

[0013] The third technical solution adopted in this invention is a method for preparing an ultra-high strength and toughness gearbox valve body, characterized by the following specific operating steps:

[0014] Step 1: Prepare ultra-high strength and toughness powder core wire for gearbox valve body using the above method;

[0015] Step 2: Select a 12CrNiMoV martensitic stainless steel substrate of suitable size, use an angle grinder to grind the rust, oil, oxide scale and dust impurities on the surface of the workpiece, after grinding, use an ultrasonic cleaning device to remove impurities, and then place the steel plate in a vacuum drying oven and store it for later use.

[0016] Step 3: First, a 3D model of the ultra-high strength and toughness gearbox valve body is created using the electric arc additive manufacturing method. Then, the model is layered and converted into a program suitable for electric arc additive manufacturing.

[0017] Step 4: Load the ultra-high strength and toughness steel flux-cored welding wire prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body layer by layer on the working substrate;

[0018] Step 5: After the ultra-high strength and toughness transmission valve body prepared in step 4 has cooled to room temperature, the ultra-high strength and toughness transmission valve body is subjected to a heat treatment process.

[0019] Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, the parts are then precision machined.

[0020] The invention is further characterized in that,

[0021] In step 3, the ultra-high strength and toughness of the gearbox valve body is modeled using PRO / E 3D solid modeling software. CAM software is used for slicing, followed by program conversion and import into the arc welding robot teach pendant for layered arc additive manufacturing. A single-layer, multi-pass, reciprocating path is selected to complete the deposition of multiple passes per layer. Non-linear areas are welded using continuous short-pass straight welding. During 3D printing, the deposition direction needs to be changed after each layer is completed before starting the next layer. The length and width of the path and the height of the additive manufacturing process are designed according to the proportions in the gearbox valve body design drawing. Additive manufacturing is performed layer by layer to accumulate the required height and width as specified in the design drawing. The non-linear welding speed is 0.3-0.55 m / m. For straight sections, the welding speed range is 0.2-0.35 m / min. For non-straight sections, the welding speed should be 0.1-0.2 m / min faster than that for straight sections. For parts with a thickness of 5 mm or less, a machining allowance of ±3 mm is required. For straight sections with a width of ≥10 mm, the swing arc welding process is used. The welding speed for swing arc welding is 0.20 m / min to 0.26 m / min, the swing arc amplitude is 10 mm to 12 mm, the swing arc frequency is 1 Hz to 2 Hz, and the swing arc dwell time is 0.1-0.2 s. When stacking multiple passes in a single layer, the design spacing ensures an overlap rate of 55%-60% between passes. The above process is converted into a program and imported into the arc welding robot.

[0022] In step 4, the specific process parameters for arc additive manufacturing are as follows: Welding process parameters: Welding voltage: 21V~23V, welding current: 140A~150A, wire extension length: 12mm~14mm, after each layer of arc cladding, the surface oxide scale and slag are removed with an angle grinder; after cooling to 150℃, the next cladding is carried out; the shielding gas is 100% Ar mixed gas, the gas flow rate is 15L / min-20L / min, and the welding speed is 280mm / min~320mm / min.

[0023] In step 5, the prepared gearbox valve body is subjected to overall heat treatment using a nitrate furnace for tempering at a temperature of 600±10℃; then it is placed in air and cooled to room temperature.

[0024] In step 6, a six-axis CNC machine tool is used to perform precision machining on the entire part. The uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm.

[0025] The fourth technical solution adopted in this invention is an ultra-high strength and toughness gearbox valve body, which is prepared by the above-mentioned method.

[0026] The beneficial effects of this invention are:

[0027] (1) When the method of the present invention is based on the preparation of ultra-high strength and toughness gearbox valve body by arc additive manufacturing, the preparation method of flux-cored welding wire is simple and the composition of the structural parts can be changed relatively easily to optimize the performance.

[0028] (2) The method of the present invention provides a novel way of manufacturing ultra-high strength and toughness transmission valve body. The mechanical properties of the manufactured ultra-high strength and toughness transmission valve body meet the actual working conditions, while avoiding the uneven structure and other phenomena that occur in the traditional manufacturing of ultra-high strength and toughness transmission valve bodies.

[0029] (3) The method of the present invention is based on electric arc additive manufacturing technology. From wire making to part forming, the forming cycle is short, the processing speed is fast, the material waste rate is low, the labor intensity is low, the manufacturing process steps are simple, the labor intensity of workers is low, and it is more conducive to automated production.

[0030] (4) The metal powder core welding wire of the present invention can not only manufacture ultra-high strength and toughness gearbox valve bodies, but also other ultra-high strength and toughness steel structural parts by changing the model, and has a wide range of applications.

[0031] (5) During the layer-by-layer deposition process of arc additive manufacturing, the part undergoes multiple heating and heat treatment processes, which can eliminate problems such as difficulty in hardening, macroscopic segregation, and anisotropy of strength and toughness present in large castings. The manufactured part has good overall mechanical properties, high manufacturing efficiency, and shortened subsequent finishing time. This invention uses arc additive manufacturing to prepare this ultra-high strength and toughness gearbox valve body part; this part has advantages such as high strength, low cost, and high manufacturing efficiency. Attached Figure Description

[0032] Figure 1 This is a microstructure image of the gearbox valve body prepared in Example 1 of the present invention;

[0033] Figure 2 This is a modeling diagram of the internal structure of the gearbox valve body prepared according to the present invention;

[0034] Figure 3 This is a physical image of the gearbox valve body printed according to Embodiment 1 of the present invention;

[0035] Figure 4 This is for Figure 3 Enlarged view of the area within the Chinese box. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0037] This invention provides a high-strength and high-toughness powder core wire for gearbox valve bodies, comprising a core powder and an outer sheath. The core powder is composed of the following powders by mass percentage: carbon powder 0.5%, manganese powder 10%–15%, chromium powder 10%–15%, nickel powder 15%–20%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%–2%, and iron powder as the balance, with the sum of the mass percentages of the above components being 100%. The outer sheath is a low-carbon steel strip, specifically composed of C: 0.021%; Mn: 0.15%; S: 0.006%; P: 0.007%; Si: 0.19%; Fe: balance. The filling rate of the powder core wire is 20wt%–25wt%.

[0038] In the powder-cored welding wire of this invention, the addition of Mn and Si elements can achieve the purpose of deoxidation, while the addition of Mn, Cr, and C elements can strengthen the iron matrix, improve strength, and enhance the mechanical properties of the structural component. The addition of Ni element is to improve the corrosion resistance of the structural component and, on the other hand, can work with Cu, Ti, and Mo elements to improve the toughness of the structural component. CeO2 powder, rare earth elements, and grain refiners are added. Through the effects of the above elements, an ultra-high strength and toughness structural component can be obtained.

[0039] This invention also provides a method for preparing ultra-high strength and toughness powder core wire for gearbox valve bodies, specifically:

[0040] Step 1: Weigh the following core powders according to their mass percentages: carbon powder 0.5%, manganese powder 10%–15%, chromium powder 10%–15%, nickel powder 15%–20%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%–2%, and iron powder balance. The sum of the mass percentages of the above components is 100%.

[0041] Step 2: All weighed powders are first alloyed using a planetary ball mill at a speed of 300-350 r / min for 4-5 hours. Then, flux-cored wires are prepared using a metal flux-cored wire drawing machine. The diameter of the flux-cored wire is reduced every 0.2 mm until it reaches a diameter of 1.6 mm. The outer sheath is made of low-carbon steel strip with the following composition: C: 0.021%; Mn: 0.15%; S: 0.006%; P: 0.007%; Si: 0.19%; Fe: balance. The filling rate of the powder-cored wire is 20wt%-25wt%.

[0042] This invention also provides a method for preparing an ultra-high strength and toughness gearbox valve body, the specific operation steps of which are as follows:

[0043] Step 1: Prepare ultra-high strength and toughness powder core wire for gearbox valve body using the above method;

[0044] Step 2: Select a 12CrNiMoV martensitic stainless steel substrate of suitable size, use an angle grinder to grind the rust, oil, oxide scale and dust impurities on the surface of the workpiece, after grinding, use an ultrasonic cleaning device to remove impurities, and then place the steel plate in a vacuum drying oven and store it for later use.

[0045] Step 3: First, a 3D model of the ultra-high strength and toughness gearbox valve body is created using the electric arc additive manufacturing method. Then, the model is layered and converted into a program suitable for electric arc additive manufacturing.

[0046] In step 3, the ultra-high strength and toughness of the gearbox valve body is modeled using PRO / E 3D solid modeling software. CAM software is used for slicing, followed by program conversion and import into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During 3D printing, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The path length, width, and height of the additive manufacturing process are designed according to the proportions in the gearbox valve body design drawing. Additive manufacturing is performed layer by layer to accumulate the required height and width as specified in the design drawing. The non-linear welding speed is 0.3 m / min-0.55 m / min, and the linear welding speed range is...

[0047] The welding speed for non-linear parts should be 0.1m / min-0.2m / min-0.35m / min, and the welding speed for non-linear parts should be 0.1m / min-0.2m / min faster than that for linear parts. Parts with a thickness of 5mm or less need to have a machining allowance of ±3mm. For linear parts with a width of ≥10mm, the swing arc welding process should be used. The welding speed for swing arc welding parts should be 0.20m / min-0.26m / min, the swing arc amplitude should be 10mm-12mm, the swing arc frequency should be 1Hz-2Hz, and the swing arc dwell time should be 0.1-0.2s. When stacking multiple passes in a single layer, the design spacing should ensure an overlap rate of 55%-60% between passes. The above process should be converted into a program and imported into the arc welding robot.

[0048] In additive manufacturing, the process is a one-time forming. For straight sections with a width of less than 10mm, the welding process can be either direct welding or sway welding. The welding current and voltage used for straight sections with a width of less than 10mm are the same as those with a width of ≥10mm, and the welding current and voltage are fixed. The heat input mainly depends on the welding speed and dwell time. If direct welding with a low speed is used, the weld bead will become narrower and thicker. If direct welding is used when the width is ≥10mm, the sides of the weld bead will not be fully filled, so the weld bead width will not meet the requirements. Therefore, for widths ≥10mm, I used a low speed + sway welding process to achieve the required weld bead width.

[0049] Step 4: Load the ultra-high strength and toughness steel flux-cored welding wire prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body layer by layer on the working substrate;

[0050] In step 4, the specific process parameters for arc additive manufacturing are as follows: Welding process parameters: Welding voltage: 21V~23V, welding current: 140A~150A, wire extension length: 12mm~14mm, after each layer of arc cladding, the surface oxide scale and slag are removed with an angle grinder; after cooling to 150℃, the next cladding is carried out; the shielding gas is 100% Ar mixed gas, the gas flow rate is 15L / min-20L / min, and the welding speed is 280mm / min~320mm / min;

[0051] Step 5: After the ultra-high strength and toughness transmission valve body prepared in step 4 has cooled to room temperature, the ultra-high strength and toughness transmission valve body is subjected to a heat treatment process.

[0052] In step 5, the prepared gearbox valve body is subjected to overall heat treatment using a nitrate furnace for tempering at a temperature of 600±10℃; then it is placed in air and cooled to room temperature.

[0053] Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, the parts are then precision machined.

[0054] In step 6, a six-axis CNC machine tool is used to perform precision machining on the entire part. The uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm.

[0055] The present invention also provides an ultra-high strength and toughness gearbox valve body, which is prepared by the method described above.

[0056] Example 1

[0057] The purpose of this invention is to provide an arc additive manufacturing method for ultra-high strength and toughness powder core wire and ultra-high strength and toughness gearbox valve body, the specific steps of which are as follows:

[0058] Step 1: Preparation of ultra-high strength and toughness flux-cored wire: Weigh the following flux-cored powders according to their mass percentages: carbon powder 0.5%, manganese powder 10%, chromium powder 10%, nickel powder 15%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%, and iron powder balance. The sum of the mass percentages of the above components is 100%. All weighed powders are first alloyed using a planetary ball mill at a speed of 300 r / min for 4 hours. The strip used to prepare the flux-cored wire is a low-carbon steel strip. After filling with powder, the diameter of the metal flux-cored wire needs to be reduced every 0.2 mm until the diameter is 1.6 mm, with a filling rate of 21.3%.

[0059] Step 2: Select a 12CrNiMoV martensitic stainless steel substrate of suitable size, and use an angle grinder to grind the rust, oil, oxide scale and dust impurities on the surface of the workpiece. After grinding, use an ultrasonic cleaning device to remove impurities, and then place the steel plate in a vacuum drying oven and store it for later use.

[0060] Step 3: Model the ultra-high strength and toughness gearbox valve body using PRO / E 3D solid modeling software; slice the material using CAM software, then convert the slices into a program and import it into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During the 3D printing process, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The length, width, and height of the additive manufacturing path are designed according to the proportions in the gearbox valve body design drawing, and additive manufacturing is repeated layer by layer. Accumulate to the height and width required by the design drawing; the welding speed for non-linear parts is 0.4m / min, and the welding speed for linear parts is 0.32m / min. For thin parts of the part, a machining allowance of ±3mm is required; for linear parts with a width ≥10mm, the swing arc welding process is adopted. The welding speed of the swing arc welding part is 0.22m / min, the swing arc amplitude is 12mm, the swing arc frequency is 1.2Hz, and the swing arc dwell time is 0.1s. When stacking multiple passes in a single layer, the design spacing ensures that the overlap rate between passes is 55%-60%. The above process is converted into a program and imported into the arc welding robot.

[0061] Step 4: Load the ultra-high strength and toughness powder-cored welding material prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body. Take out the working substrate placed in the vacuum drying oven and place it on the horizontal worktable. During the arc cladding process, a T2 copper plate twice the size of the 12CrNiMOV martensitic stainless steel should be placed under it to facilitate heat dissipation. Arc additive manufacturing process parameters: additive voltage: 21.5V, additive current: 140A, wire extension length: 12mm. After each layer of arc cladding, remove the surface oxide scale and slag with an angle grinder. After cooling to 150℃, proceed to the next cladding. The shielding gas is 100% Ar mixed gas, the gas flow rate is 18L / min, and the wire filling speed is 230mm / min.

[0062] Step 5: Perform overall heat treatment on the prepared gearbox valve body. The heat treatment is carried out in a salt nitrate furnace and tempering is performed at a temperature of 600±10℃.

[0063] Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, a six-axis CNC machine tool is used to perform precision machining on the parts. Uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm.

[0064] In Example 1, an ultra-high strength and toughness structural component was prepared using an electric arc additive manufacturing method. After mechanical property testing, the yield strength was 632 MPa, the tensile strength was 802 MPa, and the room temperature impact energy was 81.4 J. All the measured mechanical properties met the requirements of actual working conditions.

[0065] from Figure 1 As can be seen from the microstructure, the gearbox valve body parts prepared by this method are mainly composed of bainite and ferrite. These two structures have good plasticity and toughness, and the fine bainite structure has a fine grain strengthening effect. At the same time, bainite also has good mechanical properties.

[0066] from Figure 2 As can be seen, the gearbox valve body is a complex curved surface component, which is difficult to machine using traditional processes and has problems such as large machining allowances. However, electric arc additive manufacturing technology can directly print it into shape, reducing the difficulty of subsequent processing.

[0067] Figure 3 To obtain a printed image of the gearbox valve body, from Figure 3-4 As can be seen from the image, no obvious defects such as pores or cracks were found, indicating good forming and smooth transition between straight lines and arcs.

[0068] Example 2

[0069] The purpose of this invention is to provide an arc additive manufacturing method for ultra-high strength and toughness powder core wire and ultra-high strength and toughness gearbox valve body, the specific steps of which are as follows:

[0070] Step 1: Preparation of ultra-high strength and toughness flux-cored wire: Weigh the following flux-cored powders according to their mass percentages: carbon powder 0.5%, manganese powder 11.2%, chromium powder 11.2%, nickel powder 15%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%, and iron powder balance. The sum of the mass percentages of the above components is 100%. All weighed powders are first alloyed using a planetary ball mill at a speed of 300 r / min for 4 hours. The strip used to prepare the flux-cored wire is a low-carbon steel strip. After filling with powder, the diameter of the metal flux-cored wire needs to be reduced every 0.2 mm until the diameter is 1.6 mm, with a filling rate of 21.3%.

[0071] Step 2: Select a suitable 12CrNiMoV martensitic stainless steel substrate. Use an angle grinder to remove rust, oil, scale, and dust from the workpiece surface. After grinding, use an ultrasonic cleaner to remove impurities. Then, place the steel plate in a vacuum drying oven and store it for later use.

[0072] Step 3: Model the ultra-high strength and toughness gearbox valve body using PRO / E 3D solid modeling software; slice the material using CAM software, then convert the slices into a program and import it into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During the 3D printing process, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The length, width, and height of the additive manufacturing path are designed according to the proportions in the gearbox valve body design drawing, and additive manufacturing is repeated layer by layer. Accumulate to the height and width required by the design drawing; the welding speed for non-linear parts is 0.4m / min, and the welding speed for linear parts is 0.32m / min. For thin parts of the part, a machining allowance of ±3mm is required; for linear parts with a width ≥10mm, the swing arc welding process is adopted. The welding speed of the swing arc welding part is 0.20m / min, the swing arc amplitude is 12mm, the swing arc frequency is 1.2Hz, and the swing arc dwell time is 0.1s. When stacking multiple passes in a single layer, the design spacing ensures that the overlap rate between passes is 55%-60%. The above process is converted into a program and imported into the arc welding robot.

[0073] Step 4: Load the ultra-high strength and toughness powder-cored welding material prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body. Take out the working substrate placed in the vacuum drying oven and place it on a horizontal worktable. During the arc cladding process, a T2 copper plate twice the size of the 12CrNiMoV martensitic stainless steel should be placed under the substrate to facilitate heat dissipation. Arc additive manufacturing process parameters: additive voltage: 21.5V, additive current: 140A, wire extension length: 12mm. After each layer of arc cladding, remove the surface oxide scale and slag with an angle grinder. After cooling to 150℃, proceed to the next cladding. The shielding gas is 100% Ar mixed gas, the gas flow rate is 18L / min, and the wire filling speed is 230mm / min.

[0074] Step 5: After the valve body parts prepared in Step 4 have cooled to room temperature, perform a heat treatment process on the parts.

[0075] Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, the parts are precision machined as a whole. Uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm. In Example 2, an ultra-high strength and toughness structural part prepared by an electric arc additive manufacturing method was used. After mechanical property testing, the yield strength was 610.2MPa, the tensile strength was 810.86MPa, and the room temperature impact energy was 79.3J. The measured mechanical properties all meet the requirements of actual working conditions.

[0076] Example 3

[0077] The purpose of this invention is to provide an arc additive manufacturing method for ultra-high strength and toughness powder core wire and ultra-high strength and toughness gearbox valve body, the specific steps of which are as follows:

[0078] Step 1: Preparation of ultra-high strength and toughness flux-cored wire: Weigh the following flux-cored powders according to their mass percentages: carbon powder 0.5%, manganese powder 12.6%, chromium powder 12.6%, nickel powder 15%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%, and iron powder balance. The sum of the mass percentages of the above components is 100%. All weighed powders are first alloyed using a planetary ball mill at a speed of 300 r / min for 4 hours. The strip used to prepare the flux-cored wire is a low-carbon steel strip. After filling with powder, the diameter of the metal flux-cored wire needs to be reduced every 0.2 mm until the diameter is 1.6 mm, with a filling rate of 21.3%.

[0079] Step 2: Select a suitable 12CrNiMoV martensitic stainless steel substrate. Use an angle grinder to remove rust, oil, scale, and dust from the workpiece surface. After grinding, use an ultrasonic cleaner to remove impurities. Then, place the steel plate in a vacuum drying oven and store it for later use.

[0080] Step 3: Model the ultra-high strength and toughness gearbox valve body using PRO / E 3D solid modeling software; slice the material using CAM software, then convert the slices into a program and import them into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During the 3D printing process, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The length, width, and height of the additive manufacturing path are designed according to the proportions in the gearbox valve body design drawing, and additive manufacturing is repeated layer by layer. Accumulate to the height and width required by the design drawing; the welding speed for non-linear parts is 0.4m / min, and the welding speed for linear parts is 0.32m / min. For thin parts of the part, a machining allowance of ±3mm is required; for linear parts with a width ≥10mm, the swing arc welding process is adopted. The welding speed of the swing arc welding part is 0.22m / min, the swing arc amplitude is 12mm, the swing arc frequency is 1.2Hz, and the swing arc dwell time is 0.1s. When stacking multiple passes in a single layer, the design spacing ensures that the overlap rate between passes is 55%-60%. The above process is converted into a program and imported into the arc welding robot.

[0081] Step 4: Load the ultra-high strength and toughness powder-cored welding material prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body. Take out the working substrate placed in the vacuum drying oven and place it on a horizontal worktable. During the arc cladding process, a T2 copper plate twice the size of the 12CrNiMoV martensitic stainless steel should be placed under the substrate to facilitate heat dissipation. Arc additive manufacturing process parameters: additive voltage: 21.5V, additive current: 140A, wire extension length: 12mm. After each layer of arc cladding, remove the surface oxide scale and slag with an angle grinder. After cooling to 150℃, proceed to the next cladding. The shielding gas is 100% Ar mixed gas, the gas flow rate is 18L / min, and the wire filling speed is 230mm / min.

[0082] Step 5: After the valve body parts prepared in Step 4 have cooled to room temperature, perform a heat treatment process on the parts.

[0083] Step 6: After the part, which has undergone heat treatment in Step 5, cools to room temperature, the entire part is precision machined. Uneven areas on the surface are treated by milling, ensuring a machining accuracy of ±3mm required for its working condition. Example 3 uses an ultra-high strength and toughness structural component prepared using an electric arc additive manufacturing method. After mechanical property testing, the yield strength is 615.10 MPa, the tensile strength is 819.34 MPa, and the room temperature impact energy is 82.3 J. All measured mechanical properties meet the requirements of actual working conditions.

[0084] Example 4

[0085] The purpose of this invention is to provide an arc additive manufacturing method for ultra-high strength and toughness powder core wire and ultra-high strength and toughness gearbox valve body, the specific steps of which are as follows:

[0086] Step 1: Preparation of ultra-high strength and toughness flux-cored wire: Weigh the following flux-cored powders according to their mass percentages: carbon powder 0.5%, manganese powder 12.6%, chromium powder 11.6%, nickel powder 15%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.8%, and iron powder balance. The sum of the mass percentages of the above components is 100%. All weighed powders are first alloyed using a planetary ball mill at a speed of 300 r / min for 4 hours. The strip used to prepare the flux-cored wire is a low-carbon steel strip. After filling with powder, the diameter of the metal flux-cored wire needs to be reduced every 0.2 mm until the diameter is 1.6 mm, with a filling rate of 21.3%.

[0087] Step 2: Select a suitable 12CrNiMoV martensitic stainless steel substrate. Use an angle grinder to remove rust, oil, scale, and dust from the workpiece surface. After grinding, use an ultrasonic cleaner to remove impurities. Then, place the steel plate in a vacuum drying oven and store it for later use.

[0088] Step 3: Model the ultra-high strength and toughness gearbox valve body using PRO / E 3D solid modeling software; slice the material using CAM software, then convert the slices into a program and import them into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During the 3D printing process, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The length, width, and height of the additive manufacturing path are designed according to the proportions in the gearbox valve body design drawing, and additive manufacturing is repeated layer by layer. Accumulate to the height and width required by the design drawing; the welding speed for non-linear parts is 0.4m / min, and the welding speed for linear parts is 0.32m / min. For thin parts of the part, a machining allowance of ±3mm is required; for linear parts with a width ≥10mm, the swing arc welding process is adopted. The welding speed of the swing arc welding part is 0.22m / min, the swing arc amplitude is 12mm, the swing arc frequency is 1.2Hz, and the swing arc dwell time is 0.1s. When stacking multiple passes in a single layer, the design spacing ensures that the overlap rate between passes is 55%-60%. The above process is converted into a program and imported into the arc welding robot.

[0089] Step 4: Load the ultra-high strength and toughness powder-cored welding material prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body. Take out the working substrate placed in the vacuum drying oven and place it on the horizontal worktable. During the arc cladding process, a T2 copper plate twice the size of the 12CrNiMoV martensitic stainless steel should be placed under it to facilitate heat dissipation. Arc additive manufacturing process parameters: additive voltage: 21.5V, additive current: 140A, wire extension length: 12mm. After each layer of arc cladding, remove the surface oxide scale and slag with an angle grinder. After cooling to 50℃, proceed to the next cladding. The shielding gas is 100% Ar mixed gas, the gas flow rate is 18L / min, and the wire filling speed is 230mm / min.

[0090] Step 5: After the valve body parts prepared in Step 4 have cooled to room temperature, perform a heat treatment process on the parts.

[0091] Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, the parts are precision machined as a whole. Uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm. In Example 4, an ultra-high strength and toughness structural part based on an electric arc additive manufacturing method was used. After mechanical property testing, the yield strength was 622.39MPa, the tensile strength was 828.94MPa, and the room temperature impact energy was 81.5J. The measured mechanical properties all meet the requirements of actual working conditions.

[0092] Example 5

[0093] The purpose of this invention is to provide an arc additive manufacturing method for ultra-high strength and toughness powder core wire and ultra-high strength and toughness gearbox valve body, the specific steps of which are as follows:

[0094] Step 1: Preparation of ultra-high strength and toughness flux-cored wire: Weigh the following flux-cored powders according to their mass percentages: carbon powder 0.5%, manganese powder 15%, chromium powder 15%, nickel powder 1%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 2%, and iron powder balance. The sum of the mass percentages of the above components is 100%. All weighed powders are first alloyed using a planetary ball mill at a speed of 300 r / min for 4 hours. The strip used to prepare the flux-cored wire is a low-carbon steel strip. After filling with powder, the diameter of the metal flux-cored wire needs to be reduced every 0.2 mm until the diameter is 1.6 mm, with a filling rate of 21.3%.

[0095] Step 2: Select a suitable 12CrNiMoV martensitic stainless steel substrate. Use an angle grinder to remove rust, oil, scale, and dust from the workpiece surface. After grinding, use an ultrasonic cleaner to remove impurities. Then, place the steel plate in a vacuum drying oven and store it for later use.

[0096] Step 3: Model the ultra-high strength and toughness gearbox valve body using PRO / E 3D solid modeling software; slice the material using CAM software, then convert the slices into a program and import them into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During 3D printing, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The path length, width, and height of the additive manufacturing process are designed according to the proportions in the gearbox valve body design drawing. Layer-by-layer additive manufacturing is then performed. The welding process is repeated until the height and width required by the design drawing are reached. The welding speed for non-linear parts is 0.4 m / min, and the welding speed for linear parts is 0.32 m / min. For thin parts of the part, a machining allowance of ±3 mm is required. For linear parts with a width ≥ 10 mm, the swing arc welding process is adopted. The welding speed for swing arc welding is 0.26 m / min, the swing arc amplitude is 12 mm, the swing arc frequency is 1.2 Hz, and the swing arc dwell time is 0.1 s. When stacking multiple passes in a single layer, the design spacing ensures that the overlap rate between passes is 55%-60%. The above process is converted into a program and imported into the arc welding robot.

[0097] Step 4: Load the ultra-high strength and toughness powder-cored welding material prepared in Step 1 into the arc welding robot, and perform arc additive manufacturing to prepare the ultra-high strength and toughness gearbox valve body. Take out the working substrate placed in the vacuum drying oven and place it on a horizontal worktable. During the arc cladding process, a T2 copper plate twice the size of the 12CrNiMoV martensitic stainless steel should be placed under the substrate to facilitate heat dissipation. Arc additive manufacturing process parameters: additive voltage: 21.5V, additive current: 140A, wire extension length: 12mm. After each layer of arc cladding, remove the surface oxide scale and slag with an angle grinder. After cooling to 150℃, proceed to the next cladding. The shielding gas is 100% Ar mixed gas, the gas flow rate is 18L / min, and the wire filling speed is 230mm / min.

[0098] Step 5: After the valve body parts prepared in Step 4 have cooled to room temperature, perform a heat treatment process on the parts.

[0099] Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, the parts are precision machined as a whole. Uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm. In Example 5, an ultra-high strength and toughness structural part based on an electric arc additive manufacturing method is used. After mechanical property testing, the yield strength is 625.27MPa, the tensile strength is 839.22MPa, and the room temperature impact energy is 83.9J. The measured mechanical properties all meet the requirements of actual working conditions.

Claims

1. A powder-core wire material for ultra-high strength and toughness gearbox valve body, characterized in that, It includes a core powder and an outer sheath. The core powder is composed of the following powders by mass percentage: 0.5% carbon powder, 10%~15% manganese powder, 10%~15% chromium powder, 15~20% nickel powder, 1% titanium powder, 1% silicon powder, 2% molybdenum powder, 2% copper powder, 1.5%~2% CeO2 powder, and the balance being iron powder. The outer sheath is a low-carbon steel strip. The filling rate of the core wire is 20wt%-25wt%.

2. The method for preparing ultra-high strength and toughness powder core wire for gearbox valve body according to claim 1, characterized in that, Specifically: Step 1: Weigh the following core powders by mass percentage: carbon powder 0.5%, manganese powder 10%~15%, chromium powder 10%~15%, nickel powder 15~20%, titanium powder 1%, silicon powder 1%, molybdenum powder 2%, copper powder 2%, CeO2 powder 1.5%~2%, and iron powder balance. Step 2: All weighed powders are first alloyed using a planetary ball mill at a speed of 300-350 r / min for 4-5 hours. Then, flux-cored wires are prepared using a metal flux-cored wire drawing machine. The diameter of the flux-cored wire is reduced every 0.2 mm until the diameter reaches 1.6 mm. The outer sheath is made of low-carbon steel strip. The filling rate of the powder core wire is 20wt%-25wt%.

3. A method for preparing an ultra-high strength and toughness gearbox valve body, characterized in that, The specific operating steps are as follows: Step 1: Prepare ultra-high strength and toughness powder core wire for gearbox valve body using the method described in claim 2; Step 2: Select 12CrNiMoV martensitic stainless steel substrate, grind the surface of the substrate with an angle grinder, remove impurities with an ultrasonic cleaning device after grinding, and then place the substrate in a vacuum drying oven and store it for later use. Step 3: First, a 3D model of the ultra-high strength and toughness gearbox valve body is created using the electric arc additive manufacturing method. Then, the model is layered and converted into a program suitable for electric arc additive manufacturing. Step 4: The ultra-high strength and toughness gearbox valve body prepared in Step 1 is loaded into the arc welding robot using powder core wire, and the ultra-high strength and toughness gearbox valve body is prepared layer by layer by arc additive manufacturing on the substrate. Step 5: After the ultra-high strength and toughness transmission valve body prepared in step 4 has cooled to room temperature, the ultra-high strength and toughness transmission valve body is subjected to a heat treatment process. Step 6: After the parts that have undergone heat treatment in Step 5 have cooled to room temperature, the parts are precision machined as a whole.

4. The method for preparing the ultra-high strength and toughness gearbox valve body according to claim 3, characterized in that, In step 3, the ultra-high strength and toughness of the gearbox valve body is modeled using PRO / E 3D solid modeling software. CAM software is used for slicing, followed by program conversion and import into the arc welding robot teach pendant for layered arc additive manufacturing. The path selection is a single-layer, multi-pass, reciprocating path to complete multiple passes per layer. Non-linear areas use continuous short-pass straight welding. During 3D printing, after each additive layer is completed, the deposition direction needs to be changed before starting the next layer. The path length, width, and height of the additive manufacturing process are designed according to the proportions in the gearbox valve body design drawing. Additive manufacturing is performed layer by layer to accumulate the required height and width as specified in the design drawing. The welding speed for non-linear areas is 0.3 m / min-0.55 m / min, and the welding speed for linear areas is 0.2 m / min-0.35 m / min. The welding speed for non-linear areas is 0.1 m / min faster than that for linear areas. -0.2m / min; For parts with a thickness of 5mm or less, a machining allowance of ±3mm is required; For straight parts with a width of ≥10mm, the swing arc welding process is adopted. The welding speed of the swing arc welding part is 0.20m / min~0.26m / min, the swing arc amplitude is 10mm-12mm, the swing arc frequency is 1Hz-2Hz, and the swing arc dwell time is 0.1-0.2s. When stacking multiple passes in a single layer, the design spacing ensures that the overlap rate between passes is 55%-60%. The above process is converted into a program and imported into the arc welding robot.

5. The method for preparing the ultra-high strength and toughness gearbox valve body according to claim 3, characterized in that, In step 4, the specific process parameters for arc additive manufacturing are as follows: Welding process parameters: Welding voltage: 21V~23V, welding current: 140A~150A, wire extension length: 12mm~14mm, after each layer of arc cladding, the surface oxide scale and slag are removed with an angle grinder; after cooling to 150℃, the next cladding is carried out; the shielding gas is 100%Ar, the gas flow rate is 15L / min-20L / min, and the welding speed is 280mm / min~320mm / min.

6. The method for preparing the ultra-high strength and toughness gearbox valve body according to claim 3, characterized in that, In step 5, the heat treatment is carried out in a nitrate furnace for tempering at a temperature of 600±10℃; then it is placed in air and cooled to room temperature.

7. The method for preparing the ultra-high strength and toughness gearbox valve body according to claim 3, characterized in that, In step 6, a six-axis CNC machine tool is used to perform precision machining on the entire part. The uneven areas on the surface are treated by milling, while ensuring the machining accuracy required for the working conditions is ±3mm.

8. An ultra-high strength and toughness gearbox valve body, characterized in that, It is prepared by the method described in any one of claims 3-7.

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