Electric arc additive manufacturing method for dissimilar material impact rotating wheel

Abstract

The invention aims to provide an electric arc additive manufacturing method of a dissimilar material impact rotating wheel, which is characterized in that the impact rotating wheel is prepared by an electric arc fuse wire additive method, the impact rotating wheel is divided into a spoke unit and a bucket unit along the circumference, and the spoke unit and the bucket unit are made of dissimilar materials; the split spoke units are manufactured by adopting a sand mold casting, electroslag casting or integral forging forming method; and an additive area is reserved at the bucket heel of the spoke unit according to the structural characteristics of the split bucket unit, bucket unit arc fuse additive manufacturing is conducted by taking the area as a starting point, arc striking, arc stopping and anti-deformation treatment measures are adopted in the bucket arc fuse additive manufacturing process, and overall manufacturing of the impact rotating wheel is completed. According to the method, the manufacturing period can be shortened, the overall performance of the impact rotating wheel is improved, and shape and character regulation and control of the impact rotating wheel in efficient fuse wire additive manufacturing are achieved.

Description

Technical Field

[0001] The invention relates to a manufacturing process for an impact wheel, and in particular provides an arc additive manufacturing method for an impact wheel made of different materials. Background Art

[0002] The impulse turbine uses a special water guide mechanism to direct water from the pressure pipe to the runner, causing it to rotate and drive the generator rotor to generate electricity. It is mostly used in hydropower stations with high head and small flow. As the core flow component of the unit, the impulse runner is currently manufactured by traditional methods such as integral sand casting, integral forging, and CNC machining. The performance of the components and the equipment capacity of the manufactured components are difficult to meet the requirements.

[0003] Arc additive manufacturing uses arc as heat source and wire as filling material, and realizes additive manufacturing of parts through the layer-by-layer accumulation process of point-line-surface-body in the molten pool. It has the advantages of high deposition efficiency, low manufacturing cost and high material utilization, and is particularly suitable for the rapid manufacturing of large and medium-sized metal components. However, steel components manufactured by additive manufacturing with existing grades of welding wire cannot meet the specific service performance requirements of the impact wheel. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes an arc additive manufacturing method for a heterogeneous material impact runner, and develops an ultra-low carbon martensitic stainless steel wire and an additive manufacturing process method suitable for arc additive manufacturing of a water turbine impact runner. That is, according to the composition characteristics and performance requirements of the water turbine impact runner, its alloy system and the content of each element are determined, and a metal arc welding deposition method is adopted. By optimizing the deposition process parameters, a water turbine impact runner that meets the performance requirements is manufactured. The method of the present invention can shorten the manufacturing cycle and improve the overall performance of the impact runner.

[0005] The first technical problem solved by the present invention is to provide an arc additive manufacturing method for impact wheels made of different materials to meet the needs of high-quality and rapid manufacturing of impact wheels.

[0006] The second technical problem solved by the present invention is to provide an ultra-low carbon martensitic stainless steel wire for an arc-added turbine impact runner that can achieve good strength, toughness and corrosion resistance, and has low spatter, low slag and suitable surface tension.

[0007] The technical solution of the present invention is:

[0008] An arc additive manufacturing method for a heterogeneous material impact wheel, characterized in that: the impact wheel is prepared by an arc fuse additive method, the impact wheel is split into a spoke unit and a bucket unit along the circumference, and the spoke unit and the bucket unit are made of heterogeneous materials;

[0009] The split spoke unit is manufactured by sand casting, electroslag casting or integral forging;

[0010] An additive area is reserved at the heel of the spoke unit according to the structural characteristics of the bucket unit after splitting. This area is used as the starting point for the additive manufacturing of the bucket unit arc fuse. The bucket arc fuse additive manufacturing process adopts arc starting, arc ending and anti-deformation treatment measures to complete the overall manufacturing of the impact wheel.

[0011] The spoke unit is made of 20SiMn material, and the bucket unit is made of 0Cr13Ni5Mo martensitic stainless steel material.

[0012] The chemical composition requirements of the impact wheel are shown in Table 1. Combined with the arc additive manufacturing process requirements of low spatter, low slag, and appropriate surface tension, the present invention selects ultra-low carbon Ni-Mn-Cr-Mo-Cu as the alloy system of the ultra-low carbon martensitic stainless steel wire.

[0013] Table 1 Chemical composition requirements for impact runner castings for turbines (Wt%)

[0014]

[0015] Arc fuse additive manufacturing uses ultra-low carbon martensitic stainless steel wire, and the wire composition is as follows: C≤0.04%, Mn≤0.15%, Si≤0.70%, Cr 12.0-13.0%, Ni 5.00-6.00%, Mo 0.50-0.70%, S≤0.008%, P≤0.015%, Fe balance.

[0016] The preparation method of the wire material is as follows: high-purity iron, low-carbon ferromanganese, low-carbon ferrosilicon, pure carbon, metal molybdenum, metal chromium, metal nickel, and metal copper are selected as raw materials to smelt welding wire steel, and a 500kg vacuum induction furnace is used for smelting; after smelting, the metal ingot is cast into a metal ingot with a diameter of 100mm, and then the metal ingot is forged into a square billet of 50×50mm, and then rolled into a wire rod with a diameter of 8mm by a rolling mill; the wire rod is processed into a finished wire material with a diameter of 1.2mm through annealing, rough drawing, fine drawing, and winding.

[0017] As the preferred technical solution:

[0018] Arc additive manufacturing is carried out using metal arc gas shielded welding deposition method. The specific process parameters are: current 145A, voltage 23V, additive speed 600mm / min, shielding gas 98% Ar+2% CO2 mixed gas, flow rate 25mL / min, overlap between welds 30%, and interlayer temperature controlled at no more than 300℃.

[0019] Arc striking and arc ending treatment, adding arc striking plates and arc extinguishing plates, or striking and extinguishing the arc on the outermost layer of the component.

[0020] To prevent deformation and stress, a base is set up in the starting area of ​​additive manufacturing of the heel part for rigid fixation, reserved processing dimensions, and stress relief annealing is performed after welding to reduce deformation and residual stress.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The arc additive manufacturing of an impact wheel made of a different material is used, which is based on the concept of additive manufacturing of different materials and meets the needs of high-quality and rapid manufacturing of the impact wheel. The production difficulty of large impact wheels and the requirements for equipment scale are reduced, and the manufacturing difficulty is significantly reduced. Near-net forming can reduce the later processing allowance, improve metal utilization, and greatly reduce manufacturing costs and manufacturing time.

[0023] (2) The ultra-low carbon martensitic stainless steel wire used in the impact wheel of the turbine can achieve good strength, toughness and corrosion resistance, and has the advantages of low spatter, low slag and suitable surface tension. At the same time, a process method for rapid additive manufacturing of the impact wheel for the turbine is formed, which has strong practicality and promotion value and is easy to realize engineering application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The microstructure of the additive metal non-metallic inclusions of Example 1 of the present invention (non-metallic inclusions: Class A level 0, Class B level 0, Class C level 0, Class D fine system level 1);

[0025] Figure 2 This is the metallographic structure morphology of the additive metal in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments and the accompanying drawings, but is not limited thereto.

[0027] Example 1

[0028] The impact wheel is split into a spoke unit and a bucket unit along the circumference. The spoke unit after splitting is integrally formed and manufactured by electroslag casting. An additive area is reserved at the heel of the spoke unit according to the structural characteristics of the bucket unit after splitting, and the arc fuse additive manufacturing of the bucket unit is carried out with this area as the starting point.

[0029] The chemical composition (mass percentage) of the designed arc additively manufactured impact runner wire for turbine is: C 0.03%; Mn 0.15%; Si 0.60%; Cr 12.5%; Ni 5.78%; Mo 0.59%; S 0.002%; P 0.003%, and the rest is Fe.

[0030] Forming technology and additive manufacturing process of impact runner wire for water turbine:

[0031] High-purity iron, low-carbon ferromanganese, low-carbon ferrosilicon, pure carbon, metallic molybdenum and metallic nickel are selected as raw materials for smelting welding wire steel in a 500 kg vacuum induction furnace. After smelting, it is cast into a metal ingot with a diameter of 100 mm, and then the metal ingot is forged into a 50×50 mm square billet, and then rolled into a wire rod with a diameter of 8 mm by a rolling mill; the wire rod is annealed, rough drawn, fine drawn and wound into a finished wire with a diameter of 1.2 mm.

[0032] Using the low-alloy high-strength steel wire with the above composition, arc additive manufacturing is carried out by metal arc gas shielded welding (MIG) deposition method, and the process parameters are as follows: current 145A, voltage 23V, additive speed 600mm / min, shielding gas using 98% Ar+2% CO2 mixed gas, flow rate 25mL / min, overlap between welds 30%, and interlayer temperature controlled at no more than 300°C.

[0033] The average tensile strength of the additive metal 0Cr13Ni5Mo is 1030MPa, the average yield strength is 874MPa, the average elongation is 13.7%, and the average cross-sectional shrinkage is 70%, which meets the service performance requirements of the impact runner for turbines.

[0034] The overall electroslag casting and welding manufacturing of the impact runner is completed by utilizing the spoke unit formed by electroslag casting and the bucket unit manufactured by arc fuse additive manufacturing in sequence.

[0035] Table 2 Mechanical properties of additive layer 0Cr13Ni4Mo

[0036]

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An arc additive manufacturing method for a heterogeneous material impact wheel, characterized in that: The impact wheel is prepared by an arc fuse additive method. The impact wheel is divided into a spoke unit and a bucket unit along the circumference. The spoke unit and the bucket unit are made of different materials. The split spoke unit is manufactured by sand casting, electroslag casting or integral forging; An additive area is reserved at the heel of the spoke unit according to the structural characteristics of the bucket unit after splitting. This area is used as the starting point for the additive manufacturing of the bucket unit arc fuse. The bucket arc fuse additive manufacturing process adopts arc starting, arc ending and anti-deformation treatment measures to complete the overall manufacturing of the impact wheel.

2. The arc additive manufacturing method for a heterogeneous material impact wheel according to claim 1, characterized in that: The spoke unit is made of 20SiMn material, and the bucket unit is made of 0Cr13Ni5Mo martensitic stainless steel material.

3. The arc additive manufacturing method for a heterogeneous material impact wheel according to claim 1, characterized in that: Arc fuse additive manufacturing uses ultra-low carbon martensitic stainless steel wire, and the wire composition is as follows: C≤0.04%, Mn≤0.15%, Si≤0.70%, Cr 12.0-13.0%, Ni 5.00-6.00%, Mo0.50-0.70%, S≤0.008%, P≤0.015%, Fe balance.

4. The arc additive manufacturing method for a heterogeneous material impact wheel according to claim 3, characterized in that: The preparation method of the wire material is as follows: high-purity iron, low-carbon ferromanganese, low-carbon ferrosilicon, pure carbon, metal molybdenum, metal chromium, metal nickel, and metal copper are selected as raw materials to smelt welding wire steel, and a 500kg vacuum induction furnace is used for smelting; after smelting, the metal ingot is cast into a metal ingot with a diameter of 100mm, and then the metal ingot is forged into a square billet of 50×50mm, and then rolled into a wire rod with a diameter of 8mm by a rolling mill; the wire rod is processed into a finished wire material with a diameter of 1.2mm through annealing, rough drawing, fine drawing, and winding.

5. The arc additive manufacturing method for a heterogeneous material impact wheel according to claim 1, characterized in that: Arc additive manufacturing is carried out using metal arc gas shielded welding deposition method. The specific process parameters are: current 145A, voltage 23V, additive speed 600mm / min, shielding gas 98% Ar+2% CO2 mixed gas, flow rate 25mL / min, overlap between welds 30%, and interlayer temperature controlled at no more than 300℃.

6. The arc additive manufacturing method for a heterogeneous material impact wheel according to claim 1, characterized in that: Arc striking and arc ending treatment, adding arc striking plates and arc extinguishing plates, or striking and extinguishing the arc on the outermost layer of the component.

7. The arc additive manufacturing method for a heterogeneous material impact wheel according to claim 1, characterized in that: To prevent deformation and stress, a base is set up in the starting area of ​​additive manufacturing of the heel part for rigid fixation, reserved processing dimensions, and stress relief annealing is performed after welding to reduce deformation and residual stress.

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