Modified structure for bearing surface of fan impeller shaft and modification method

Abstract

The application discloses a modified structure for a fan impeller bearing surface, comprising a transition layer prepared on the fan impeller bearing surface through arc cladding, and a TC4 layer prepared above the transition layer through arc cladding and laser remelting. The modified structure for the fan impeller bearing surface solves the problem of the falling-off of the TC4 surface modification layer caused by the local accumulation of brittle phases in the prior art. The application further discloses a modification method for a fan impeller bearing surface.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of stainless steel surface modification method, and relates to a modified structure for a fan impeller bearing surface. BACKGROUND

[0002] Titanium alloy material has excellent properties such as high strength, corrosion resistance, high temperature resistance and low temperature resistance, and can adapt to various harsh working environments, and is often used in the front fan and low-pressure compressor of an aero-engine. The impeller processed from titanium alloy has excellent corrosion resistance to corrosive substances in a steam turbine, and the turbine blade made of the titanium alloy does not appear pitting, stress corrosion and corrosion fatigue when used in an environment containing chlorides, hydroxides and sulfates. Similarly, the dust and corrosive gas entering the fan also makes the working environment of the impeller bearing in a wear, corrosion and high temperature condition. If the wear resistance of the impeller bearing is improved, a titanium alloy material with high hardness and good wear resistance can be used, but this not only brings difficulties to the manufacturing process of the impeller, but also is not reasonable from the economic point of view. Therefore, improving the surface quality of the impeller bearing and performing surfacing or spray welding of a TC4 layer on the seriously worn and corroded parts of the impeller bearing to achieve wear resistance and corrosion resistance is an economic and reasonable solution in engineering.

[0003] Stainless steel is a commonly used material for the impeller bearing, and has excellent mechanical properties, cold forming properties, good corrosion resistance and weldability. However, because of the large difference in composition between TC4 and stainless steel, pitting corrosion, crevice corrosion and even overall corrosion will occur in a short time. In the surfacing or spray welding process, the FeTi phase and the cavity phase Fe2Ti generated by the most important elements Fe and Ti of the titanium alloy and the stainless steel are very easy to produce brittle fracture, the hardness of which cannot be accurately measured. In addition, the small amount of nickel in the stainless steel is usually dissolved in the intermetallic phase and the solid solution, which will form an additional brittle phase with chromium. The local accumulation of this brittle phase will cause serious cold cracking, resulting in the peeling of the surface modification layer.

[0004] In addition, because titanium has a high melting point, poor thermal conductivity and small specific heat, if the high-temperature residence time of the overheated zone is too long or the cooling speed is too slow during welding, obvious coarse grains will appear in the overheated zone. The appearance of these coarse grains will cause the plasticity of the overheated zone to decrease, resulting in the decrease of the mechanical properties of the substrate and the difficulty of bearing axial and radial loads. In engineering, laser irradiation is used to melt the substrate, and the required alloying elements are added to form an alloying modification layer with a thickness of several hundred microns to one millimeter, so as to improve the surface properties of the material. However, in this preparation process, the high requirement for raw materials, the large amount of time and cost required for preparing qualified powder, and the decrease of the quality and stability of the workpiece caused by the failure of the powder particle size, powder distribution and sphericity to meet the requirements will indirectly increase the cost of preparing the workpiece and reduce the efficiency of preparing the surface modification layer. SUMMARY

[0005] The purpose of the present application is to provide a modified structure for the bearing surface of a fan impeller, which solves the problem of the existing technology that the modified layer of TC4 surface falls off due to the local accumulation of brittle phase.

[0006] Another purpose of the present application is to provide a modification method for the bearing surface of a fan impeller.

[0007] The technical solution adopted by the present application is a modified structure for the bearing surface of a fan impeller, which comprises a transition layer prepared by arc cladding on the bearing surface of the fan impeller, and a TC4 layer prepared by arc cladding and laser remelting above the transition layer.

[0008] The present application is also characterized in that,

[0009] When preparing the transition layer, a metal powder core welding wire is used, which is composed of the following raw material components in mass percentage: 75%-80% of Inconel 625 nickel-based alloy with skin and 20%-25% of metal powder core, and the sum of the above component mass percentages is 100%; the metal powder core is composed of the following raw material components in mass percentage: nickel powder 63-65%, chromium powder 20-23%, niobium powder 3-4%, molybdenum powder 3-5%, iron powder 3-5%, titanium powder 0.5-1%, aluminum powder 0.5-1%, boron nitride 0.5-1%, silicon powder 0.5-1%, graphite 0.1-0.3%, cerium oxide 0.2-0.3%, and the sum of the above component mass percentages is 100%.

[0010] Another technical solution adopted by the present application is a modification method for the bearing surface of a fan impeller, which prepares the above-mentioned modified structure for the bearing surface of a fan impeller, and is specifically implemented according to the following steps:

[0011] Step 1, prepare a metal powder core welding wire for the transition layer;

[0012] Step 2, place the metal powder core welding wire prepared in step 1 into the wire feeding mechanism of the welding robot to perform arc cladding on the bearing surface of the fan impeller and cool it down, and after the surfacing is completed, the required transition layer is obtained;

[0013] Step 3, place the solid core TC4 welding wire into the wire feeding mechanism of the welding robot to directly perform arc cladding on the transition layer prepared in step 2 and cool it down, and after the surfacing is completed, the TC4 layer is obtained, then laser remelting is performed on the surface of the TC4 layer obtained by arc cladding and cooled down, and the surface modification layer is obtained, thereby obtaining the modified structure for the bearing surface of the fan impeller.

[0014] The second technical solution of the present application is also characterized in that,

[0015] Step 1 is specifically implemented according to the following steps:

[0016] Step 1.1, the following raw material components are weighed according to mass percentage: nickel powder 63-65%, chromium powder 20-23%, niobium powder 3-4%, molybdenum powder 3-5%, iron powder 3-5%, titanium powder 0.5-1%, aluminum powder 0.5-1%, boron nitride 0.5-1%, silicon powder 0.5-1%, graphite 0.1-0.3%, cerium oxide 0.2-0.3%, the sum of the above components is 100% by mass percentage;

[0017] Step 1.2, the raw materials weighed in step 1.1 are mixed uniformly and placed in a vacuum tube furnace for heating, holding, drying, and then cooled to room temperature to obtain a metal powder core;

[0018] Step 1.3, the Inconel 625 nickel-based alloy strip is rolled into a U-shaped welding strip by a wire drawing machine, then the metal powder core obtained in step 1.1 is placed in the U-shaped welding strip, then the opening side of the U-shaped welding strip is pressed to cover the metal powder core, then the U-shaped welding strip is rolled through an O-shaped rolling to close the lap O-shaped welding wire, then the lap O-shaped welding wire is drawn to reduce the diameter, and then the surface impurities and oil stains of the welding wire are removed with cotton cloth dipped in acetone to obtain a metal powder core welding wire for the transition layer.

[0019] Step 1.2, the raw materials are mixed as follows: the weighed raw material powders are poured into a vibrating powder mixer and vibrated at a frequency of 1500-2000 times / min for 60-90 min; in step 1.2, the raw materials are dried in a vacuum tube furnace, specifically, 99.9% Ar gas is introduced into the vacuum tube furnace, the drying temperature is 150-200°C, and the drying time is 60-90 min.

[0020] In the arc cladding process for preparing the transition layer in step 2, shielded metal arc welding is used, and the protective gas is composed of 98% Ar gas and 2% CO2 gas by mass percentage.

[0021] In the arc cladding process for preparing the transition layer in step 2, the welding current is 165-170 A, the welding voltage is 17 V, the amplitude is 8 mm, and the welding speed is 0.25-0.30 m / min.

[0022] In step 2, the welding method for preparing the transition layer is multi-pass deposition, and the overlap rate of the last pass cladding and the previous pass is 40%.

[0023] In step 3, the solid core TC4 welding wire is used for arc cladding, and shielded metal arc welding is used, and the protective gas is 99.9% Ar gas;

[0024] In step 3, the solid core TC4 welding wire is used for arc cladding, and the welding parameters are as follows: welding current 115-120 A, welding voltage 11-12 V, amplitude 0 mm, and welding speed 0.7 m / min.

[0025] The welding mode of the solid core TC4 welding wire in step 3 is multi-pass deposition, and the overlap rate of the last pass cladding and the previous pass is 40%.

[0026] The process parameters of the laser remelting in step 3 are as follows: the laser power is 100-140 W, the spot diameter is 80-120 mu m, the scanning speed is 0.9 m / s, and the protective gas is 99.9% Ar gas.

[0027] The beneficial effects of the present application are:

[0028] (1) The modified structure for the surface of the fan impeller bearing of the present application adds a transition layer between the TC4 modified layer and the surface of the fan impeller bearing, uses metal powder core type welding wire for the preparation of the transition layer, the forming quality of the transition layer is excellent, there is no obvious defect and slag, the welding arc smoke is small, and the TC4 surface modified layer prepared by using the metal powder core type welding wire and the transition layer prepared by using the metal powder core type welding wire are combined well, and the corrosion resistance and friction resistance are excellent.

[0029] (2) The present application uses the cladding method of the metal inert gas welding to manufacture the transition layer on the surface of the 316L stainless steel bearing, the arc and the droplet transition are stable during the surfacing process, the welding spatter is less, the argon can prevent the oxidation of the solute metal, the weld forming quality is high, and the welding process is completed by the robot, and the production efficiency is high.

[0030] (3) The metal powder core type welding wire production process is simple, convenient to operate, high in controllability of composition, flexible in adjustment, low in cost, can realize continuous production, and the metal powder core type welding wire adopts Inconel 625 alloy strips and metal powder cores, Ni element is the most contented alloying element in the Inconel 625 alloy strips and the metal powder cores, forms the matrix structure of the transition layer, the Ni element is easy to dissolve most of the metal elements to form a solid solution, cannot occur allotropy transformation, maintains stable austenite structure, and the Ni element combines with Al, Ti and other elements to form gamma prime and gamma double prime phases which can strengthen mechanical properties; Cr element can generate a dense oxide film, ensures the corrosion resistance of the transition layer metal, slows down the composition change, reduces the corrosion potential difference between the 316L stainless steel and the transition layer, and can be dissolved into the nickel element to cause lattice distortion to improve the mechanical properties of the transition layer as an important component element of the nickel-based alloy, the appropriate amount of Cr plays a good solid solution strengthening effect, causes lattice distortion, and improves the mechanical properties of the alloy; the appropriate amount of Ti element can react with C and N to generate hard phases in the intergranular, pin the boundary to hinder the slip of the grain boundary, hinder the grain, improve the hardness of the alloy to a certain extent, and improve the pitting corrosion resistance and crevice corrosion resistance of the alloy; Fe element is the main component of the 316L stainless steel bearing matrix, and the addition of the Fe element can slow down the dilution of the matrix to the transition layer, reduce the macrosegregation phenomenon between the transition layer and the matrix, and inhibit the segregation phenomenon between the matrix and the transition layer in the welding process; CeO2 as a high melting point compound only partially decomposes at high temperatures in the welding process, can be used as a nucleation site, inhibits the precipitation of harmful phases, and inhibits the possibility of crack occurrence in the preparation process of the transition layer; Mo and Nb elements can be dissolved in the nickel matrix to improve the mechanical strength of the nickel-based alloy, and because the atomic radii of Mo and Nb are large, the solid solution strengthening effect is significant. At the same time, they are the formation elements of M 23 C6 strengthening phases distributed in the grains and the grain boundaries, which can play the roles of dispersion strengthening and grain boundary strengthening.

[0031] (4) The flux-cored arc welding equipment has extremely low cost, can realize automatic production, has high production efficiency, and the laser remelting process improves the performance of the arc cladding surface modification layer. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1is a friction and wear test wear loss result diagram of a fan impeller bearing surface modified structure modified by using the modification method for a fan impeller bearing surface of embodiment 2 of the present application;

[0033] Figure 2 is a microstructure diagram of a fan impeller bearing surface modified structure modified by using the modification method for a fan impeller bearing surface of embodiment 2 of the present application;

[0034] Figure 3 is a microstructure diagram of a transition layer in a fan impeller bearing surface modified structure modified by using the modification method for a fan impeller bearing surface of embodiment 2 of the present application;

[0035] Figure 4 is an element line scan diagram of a modified layer and a transition layer of a fan impeller bearing surface modified structure modified by using the modification method for a fan impeller bearing surface of embodiment 2 of the present application. DETAILED DESCRIPTION

[0036] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0037] The modification structure for a fan impeller bearing surface of the present application comprises a transition layer prepared by arc cladding on the surface of the fan impeller bearing, and a TC4 layer prepared by arc cladding and laser remelting above the transition layer; the metal powder core welding wire is used to prepare the transition layer, and the metal powder core welding wire is composed of the following raw material components in mass percentage: 75%-80% of Inconel 625 nickel-based alloy with skin and 20%-25% of metal powder core, and the sum of the mass percentages of the above components is 100%; the metal powder core is composed of the following raw material components in mass percentage: nickel powder 63-65%, chromium powder 20-23%, niobium powder 3-4%, molybdenum powder 3-5%, iron powder 3-5%, titanium powder 0.5-1%, aluminum powder 0.5-1%, boron nitride 0.5-1%, silicon powder 0.5-1%, graphite 0.1-0.3%, cerium oxide 0.2-0.3%, and the sum of the mass percentages of the above components is 100%.

[0038] The modification method for a fan impeller bearing surface of the present application is used to prepare the above-mentioned modification structure for a fan impeller bearing surface, and is specifically implemented according to the following steps:

[0039] Step 1, preparing the metal powder core welding wire for the transition layer; specifically implemented according to the following steps:

[0040] Step 1.1, the following raw material components are weighed according to mass percentage: nickel powder 63-65%, chromium powder 20-23%, niobium powder 3-4%, molybdenum powder 3-5%, iron powder 3-5%, titanium powder 0.5-1%, aluminum powder 0.5-1%, boron nitride 0.5-1%, silicon powder 0.5-1%, graphite 0.1-0.3%, cerium oxide 0.2-0.3%, the sum of the above components is 100% by mass percentage;

[0041] Step 1.2, the raw materials weighed in step 1.1 are mixed uniformly and placed in a vacuum tube furnace for heating, holding, drying, and then cooled to room temperature to obtain a metal powder core;

[0042] Step 1.3, the Inconel 625 nickel-based alloy strip is drawn by a wire drawing machine to form a U-shaped welding strip from a flat rolled strip, then the metal powder core obtained in step 1.1 is placed in the U-shaped welding strip, then the opening side of the U-shaped welding strip is pressed to cover the metal powder core, then the U-shaped welding strip is rolled through an O-shaped rolling to close the lap O-shaped welding wire, then the lap O-shaped welding wire is drawn to reduce the diameter, and then the surface impurities and oil stains of the welding wire are removed with cotton cloth dipped in acetone to obtain a metal powder core welding wire for the transition layer.

[0043] The raw material mixing in step 1.2 is as follows: the weighed raw material powder is poured into a vibrating powder mixer and vibrated at a frequency of 1500-2000 times / min for 60-90 min; in step 1.2, the raw materials are dried in a vacuum tube furnace, specifically, 99.9% Ar gas is introduced into the vacuum tube furnace, the drying temperature is 150-200°C, and the drying time is 60-90 min;

[0044] Step 2, the metal powder core welding wire prepared in step 1 is placed in the wire feeding mechanism of the welding robot to perform arc cladding on the surface of the fan impeller bearing and cooling, during welding, gas shielded arc welding is used, the protective gas is composed of 98% Ar gas and 2% CO2 gas by mass percentage, the welding current is 165-170 A, the welding voltage is 17 V, the amplitude is 8 mm, the welding speed is 0.25-0.30 m / min, multi-pass deposition is used, the overlap rate of the last pass cladding and the previous pass is 40%, and the desired transition layer is obtained after the surfacing is completed;

[0045] Step 3, put the solid core TC4 welding wire into the welding robot wire feeding mechanism, adopt gas tungsten arc welding, the protective gas is 99.9% Ar gas, directly arc cladding and cooling on the transition layer prepared in step 2, the welding current is 115A-120A, the welding voltage is 11-12V, the swing is 0mm, the welding speed is 0.7m / min, adopt multi-pass deposition, the overlap rate of the last pass cladding and the previous pass is 40%, after the surfacing is completed, the TC4 layer is obtained, then the surface of the TC4 layer obtained by arc cladding is laser remelted and cooled, the laser power is 100-140W, the spot diameter is 80-120μm, the scanning speed is 0.9m / s, the protective gas is 99.9% Ar gas, the surface modification layer is obtained, and the modified structure of the surface of the fan impeller bearing is obtained.

[0046] Example 1

[0047] On the basis of example 1, the lap O-shaped welding wire in step 1.3 is drawn to a diameter of 1.6mm.

[0048] Example 2

[0049] The method for modifying the surface of the fan impeller bearing is specifically implemented according to the following steps:

[0050] Step 1, the raw materials are weighed according to the mass percentage, the metal powder core welding wire is composed of the following raw material components according to the mass percentage: 80% of Inconel 625 nickel-based alloy with skin and 20% of metal powder core, the metal powder core is composed of the following raw material components according to the mass percentage: nickel powder 65%, chromium powder 20%, niobium powder 5%, molybdenum powder 3%, iron powder 4%, titanium powder 1%, aluminum powder 0.5%, boron nitride 0.5%, silicon powder 0.5%, graphite 0.3%, cerium oxide 0.2%, and the sum of the above component mass percentages is 100%.

[0051] Step 2, pour the weighed powder into the vibration powder mixer, the vibration frequency is 1500 times / min, and the vibration time is 60min. Then place the mixed alloy powder in the tube furnace for drying, introduce 99.9% Ar gas, the drying temperature is 180℃, and the drying time is 75min.

[0052] Step 3, the Inconel 625 alloy strip is rolled into a U-shaped welding strip by a wire drawing machine, then the dried mixed metal powder obtained in step 2 is put into the U-shaped welding strip as a metal powder core, then the U-shaped welding strip is pressed to cover the metal powder core on one side by a clamping device, and the lap O-shaped welding wire is closed by the wire drawing machine, the powder filling speed and amount are controlled during the process; and the rough welding wire is drawn to a diameter of 1.6mm again, the surface impurities and oil stains of the welding wire are removed with cotton soaked in acetone, and a transition layer metal powder core welding wire is prepared.

[0053] Step 4, the welding wire obtained in step 3 is put into the welding robot wire feeding mechanism to perform arc cladding on the surface of the fan blade bearing, i.e. 316L stainless steel, and cooling, the arc cladding process parameters are: welding current is 160 A, welding voltage is 17 V, swing is 8 mm, welding speed is 0.30 m / min, and the welding mode adopts multi-pass deposition, the overlap between the last pass cladding and the previous pass is 40%, and the transition layer is obtained after the surfacing is completed.

[0054] Step 5, the commercial solid TC4 welding wire is put into the welding robot wire feeding mechanism to directly perform arc cladding on the transition layer prepared in step 4 and cooling, the arc cladding process parameters are: welding current is 120 A, welding voltage is 12 V, swing is 0 mm, welding speed is 0.7 m / min, and the welding mode adopts multi-pass deposition, the overlap between the last pass cladding and the previous pass is 40%, and the protective gas is 99.9% Ar gas.

[0055] After the surfacing is completed, the surface modification layer is remelted by a laser device and cooled, the laser power is 120 W, the scanning speed is 0.9 m / s, the protective gas is 99.9% Ar gas, and the target corrosion-resistant and friction-resistant fan blade bearing surface modification structure is prepared.

[0056] After the preparation is completed, the surface modification layer is subjected to electrochemical corrosion experiment in 3.5% NaCl corrosion solution. It is found through experimental test that the open circuit potential of the base material (316L stainless steel) is-0.533 V, the open circuit potential of the surface modification layer is-0.36 V, the self-corrosion potential of the base material (316L stainless steel) is-1.1137 V, the self-corrosion potential of the surface modification layer is-1.0355 V, the current size on the electrode unit area of the base material (316L stainless steel) is 2.5119*10 -5 A·cm -2 , and the current size on the electrode unit area of the surface modification layer is 1.4454*10 -4 A·cm -2 . The lower the open circuit potential, the less the tendency of corrosion of the material, the current size on the electrode unit area is the corrosion rate of the polarization process, and the value is the corrosion speed of the material, the greater the current, the faster the corrosion speed, and the corrosion resistance of the surface modification layer is greatly improved compared with the base material (316L stainless steel). Then, the surface modification layer is subjected to room temperature pin-on-disk friction and wear experiment, the load is 5 N, and the counter-plate material is 45# steel. As shown in Figure 1 , the base material wear loss is 0.50 mg, and the surface modification layer wear loss is 0.23 mg. The wear loss can directly show the friction degree of the material, and the lower the wear loss, the better the friction resistance. The corrosion resistance and friction resistance of the surface modification layer are greatly improved compared with the base material. The microstructure of the surface modification layer is as shown in Figure 2As shown, the microstructure of the surface modification layer is mainly manifested as widmanstatten structure, which can often exhibit good mechanical properties and good thermal stability, and the microstructure of the transition layer is mainly composed of columnar crystals and cellular crystals, as shown Figure 3 As shown, the transition layer and the surface modification layer are composed of columnar crystals and cellular crystals, and the interface exhibits good combination of the transition layer and the 316L stainless steel substrate, and the interface has few defects; as shown, the composition of the transition layer and the surface modification layer is smooth, and the elements slightly fluctuate; according to the analysis of the microstructure, the composition distribution, the corrosion performance test and the friction and wear experiment, the surface modification layer has excellent corrosion resistance and friction resistance, the transition layer and the surface modification layer have good bonding force with the substrate, and the prepared fan impeller bearing structure part meets the performance requirements. Figure 4 Example 3

[0057] The application is used for modifying the structure of the surface of a fan impeller bearing, which comprises a transition layer prepared on the surface of the fan impeller bearing by arc cladding, and a TC4 layer prepared above the transition layer by arc cladding and laser remelting; the metal powder core welding wire is used to prepare the transition layer, and the metal powder core welding wire is composed of the following raw material components in percentage by mass: 75% of Inconel 625 nickel-based alloy with a skin and 25% of metal powder core, and the sum of the above component percentages by mass is 100%; the metal powder core is composed of the following raw material components in percentage by mass: nickel powder 63%, chromium powder 20%, niobium powder 4%, molybdenum powder 5%, iron powder 5%, titanium powder 1%, aluminum powder 0.5%, boron nitride 0.5%, silicon powder 0.5%, graphite 0.2%, cerium oxide 0.3%, and the sum of the above component percentages by mass is 100%.

[0058] The application is used for modifying the structure of the surface of a fan impeller bearing, which comprises a transition layer prepared on the surface of the fan impeller bearing by arc cladding, and a TC4 layer prepared above the transition layer by arc cladding and laser remelting; the metal powder core welding wire is used to prepare the transition layer, and the metal powder core welding wire is composed of the following raw material components in percentage by mass: 75% of Inconel 625 nickel-based alloy with a skin and 25% of metal powder core, and the sum of the above component percentages by mass is 100%; the metal powder core is composed of the following raw material components in percentage by mass: nickel powder 63%, chromium powder 20%, niobium powder 4%, molybdenum powder 5%, iron powder 5%, titanium powder 1%, aluminum powder 0.5%, boron nitride 0.5%, silicon powder 0.5%, graphite 0.2%, cerium oxide 0.3%, and the sum of the above component percentages by mass is 100%.

[0059] The application is used for modifying the structure of the surface of a fan impeller bearing, which comprises a transition layer prepared on the surface of the fan impeller bearing by arc cladding, and a TC4 layer prepared above the transition layer by arc cladding and laser remelting; the metal powder core welding wire is used to prepare the transition layer, and the metal powder core welding wire is composed of the following raw material components in percentage by mass: 75% of Inconel 625 nickel-based alloy with a skin and 25% of metal powder core, and the sum of the above component percentages by mass is 100%; the metal powder core is composed of the following raw material components in percentage by mass: nickel powder 63%, chromium powder 20%, niobium powder 4%, molybdenum powder 5%, iron powder 5%, titanium powder 1%, aluminum powder 0.5%, boron nitride 0.5%, silicon powder 0.5%, graphite 0.2%, cerium oxide 0.3%, and the sum of the above component percentages by mass is 100%.

[0060] Step 1.1, the following raw material components are weighed according to percentage by mass: nickel powder 63%, chromium powder 20%, niobium powder 4%, molybdenum powder 5%, iron powder 5%, titanium powder 1%, aluminum powder 0.5%, boron nitride 0.5%, silicon powder 0.5%, graphite 0.2%, cerium oxide 0.3%, and the sum of the above component percentages by mass is 100%;

[0061] Step 1.2, the raw materials weighed in step 1.1 are mixed uniformly, placed in a vacuum tube furnace for heating, heat preservation and drying, and then cooled to room temperature to obtain the metal powder core;

[0062]

[0063] ​Step 1.3, the Inconel 625 nickel-based alloy strip skin is rolled into a U-shaped welding strip by a wire drawing machine from a flat shape, then the metal powder core obtained in step 1.1 is put into the U-shaped welding strip, then the opening side of the U-shaped welding strip is pressed to cover the metal powder core, then the U-shaped welding strip is rolled through the O-shaped rolling closure by the wire drawing machine to form a lap O-shaped welding wire, then the lap O-shaped welding wire is drawn to reduce the diameter, and then the impurities and oil stains on the surface of the welding wire are removed by using cotton cloth dipped in acetone, thereby preparing the metal powder core welding wire for the transition layer.

[0064] In step 1.2, the raw material mixing is specifically as follows: the weighed raw material powder is poured into a vibration powder mixer to mix for 60 minutes at a vibration frequency of 1500 times per minute; in step 1.2, the raw material powder is dried in a vacuum tube furnace, specifically by introducing 99.9% Ar gas into the vacuum tube furnace, the drying temperature is 150°C, and the drying time is 60 minutes.

[0065] Step 2, the metal powder core welding wire prepared in step 1 is put into the wire feeding mechanism of the welding robot to perform arc cladding on the surface of the fan impeller bearing and cooling, during welding, gas shielded arc welding is adopted, the protective gas is composed of 98% Ar gas and 2% CO2 gas by mass percentage, the welding current is 165 A, the welding voltage is 17 V, the amplitude is 8 mm, the welding speed is 0.25 m / min, multi-pass deposition is adopted, the overlap rate of the subsequent cladding and the previous pass is 40%, and the required transition layer is obtained after the surfacing is completed.

[0066] Step 3, the solid core TC4 welding wire is put into the wire feeding mechanism of the welding robot, gas shielded arc welding is adopted, the protective gas is 99.9% Ar gas, the transition layer prepared in step 2 is directly arc cladded and cooled, the welding current is 115 A, the welding voltage is 11 V, the amplitude is 0 mm, the welding speed is 0.7 m / min, multi-pass deposition is adopted, the overlap rate of the subsequent cladding and the previous pass is 40%, the TC4 layer is obtained after the surfacing is completed, then the surface of the TC4 layer obtained by arc cladding is laser remelted and cooled, the laser power is 100 W, the spot diameter is 80 μm, the scanning speed is 0.9 m / s, the protective gas is 99.9% Ar gas, the surface modification layer is obtained, and the modified structure of the fan impeller bearing surface is obtained.

[0067] Example 4

[0068] The application is used for the modification structure of the bearing surface of the fan impeller, comprising a transition layer prepared on the bearing surface of the fan impeller by arc cladding, and a TC4 layer prepared above the transition layer by arc cladding and laser remelting; the metal cored welding wire is used to prepare the transition layer, and the metal cored welding wire is composed of the following raw material components in percentage by mass: 78% of Inconel 625 nickel-based alloy with skin and 22% of metal cored; the sum of the above component percentages by mass is 100%; the metal cored is composed of the following raw material components in percentage by mass: 64% of nickel powder, 22% of chromium powder, 3% of niobium powder, 4% of molybdenum powder, 4% of iron powder, 0.8% of titanium powder, 0.8% of aluminum powder, 0.5% of boron nitride, 0.5% of silicon powder, 0.2% of graphite, 0.2% of cerium oxide, and the sum of the above component percentages by mass is 100%.

[0069] The application is used for the modification method of the bearing surface of the fan impeller, and the above modification structure of the bearing surface of the fan impeller is prepared, and the method is specifically implemented according to the following steps:

[0070] Step 1, the metal cored welding wire for preparing the transition layer is prepared; the method is specifically implemented according to the following steps:

[0071] Step 1.1, the following raw material components are weighed according to percentage by mass: 64% of nickel powder, 22% of chromium powder, 3% of niobium powder, 4% of molybdenum powder, 4% of iron powder, 0.8% of titanium powder, 0.8% of aluminum powder, 0.5% of boron nitride, 0.5% of silicon powder, 0.2% of graphite, 0.2% of cerium oxide, and the sum of the above component percentages by mass is 100%;

[0072] Step 1.2, the raw materials weighed in step 1.1 are uniformly mixed, placed in a vacuum tube furnace for heating, heat preservation and drying, and then cooled to room temperature to obtain the metal cored;

[0073] Step 1.3, the Inconel 625 nickel-based alloy with skin is rolled into a U-shaped welding strip by a wire drawing machine from a planar shape, then the metal cored obtained in step 1.1 is put into the U-shaped welding strip, then the opening side of the U-shaped welding strip is pressed to cover the metal cored, then the U-shaped welding strip is rolled through the O-shaped rolling closure to form a lap O-shaped welding wire through the wire drawing machine, then the lap O-shaped welding wire is drawn to reduce the diameter, and then the welding wire surface impurities and oil stains are removed by using cotton cloth dipped in acetone to prepare the metal cored welding wire for the transition layer.

[0074] In step 1.2, the raw materials are mixed by pouring the weighed raw material powder into a vibration powder mixer to vibrate and mix at a vibration frequency of 1700 times / min for 75 min; in step 1.2, the raw materials are heated, heat preserved and dried in a vacuum tube furnace, and 99.9% Ar gas is introduced into the vacuum tube furnace, the drying temperature is 180 DEG C, and the drying time is 70 min;

[0075] Step 2, the metal cored wire prepared in step 1 is put into the wire feeding mechanism of the welding robot to perform arc cladding on the surface of the fan impeller bearing and cooling, during welding, shielded metal arc welding is adopted, the protective gas is composed of 98% Ar gas and 2% CO2 gas in mass percentage, the welding current is 168 A, the welding voltage is 17 V, the amplitude is 8 mm, the welding speed is 0.3 m / min, multi-pass deposition is adopted, the overlap rate of the last pass cladding and the previous pass is 40%, and the transition layer is obtained after surfacing is completed;

[0076] Step 3, the solid core TC4 wire is put into the wire feeding mechanism of the welding robot, shielded metal arc welding is adopted, the protective gas is 99.9% Ar gas, arc cladding is directly performed on the transition layer prepared in step 2 and cooling, the welding current is 117 A, the welding voltage is 11 V, the amplitude is 0 mm, the welding speed is 0.7 m / min, multi-pass deposition is adopted, the overlap rate of the last pass cladding and the previous pass is 40%, the TC4 layer is obtained after surfacing is completed, then the surface of the TC4 layer obtained by arc cladding is subjected to laser remelting and cooling, the laser power is 120 W, the spot diameter is 100 μm, the scanning speed is 0.9 m / s, the protective gas is 99.9% Ar gas, the surface modification layer is obtained, and the modified structure of the surface of the fan impeller bearing is obtained.

[0077] Example 5

[0078] The application is used for modifying the structure of the surface of a fan impeller bearing, comprising a transition layer prepared by arc cladding on the surface of the fan impeller bearing, and a TC4 layer prepared by arc cladding and laser remelting above the transition layer; the metal cored wire is used to prepare the transition layer, the metal cored wire is composed of the following raw material components in mass percentage: 80% Inconel 625 nickel-based alloy with a skin and 20% metal core, and the sum of the mass percentages of the above components is 100%; the metal core is composed of the following raw material components in mass percentage: nickel powder 65%, chromium powder 20%, niobium powder 4%, molybdenum powder 3%, iron powder 4%, titanium powder 0.5%, aluminum powder 1%, boron nitride 1%, silicon powder 1%, graphite 0.3%, cerium oxide 0.2%, and the sum of the mass percentages of the above components is 100%.

[0079] The application is used for a modification method for the surface of a fan impeller bearing, and the above-mentioned modified structure for the surface of the fan impeller bearing is prepared according to the following steps:

[0080] Step 1, a metal cored wire for preparing a transition layer is prepared; the following steps are specifically implemented:

[0081] Step 1.1, the following raw material components are weighed according to mass percentage: nickel powder 65%, chromium powder 20%, niobium powder 4%, molybdenum powder 3%, iron powder 4%, titanium powder 0.5%, aluminum powder 1%, boron nitride 1%, silicon powder 1%, graphite 0.3%, cerium oxide 0.2%, the sum of the mass percentage of the above components is 100%;

[0082] Step 1.2, the raw materials weighed in step 1.1 are mixed uniformly and placed in a vacuum tube furnace for heating, holding, drying and cooling to room temperature to obtain a metal powder core;

[0083] Step 1.3, the Inconel 625 nickel-based alloy strip is rolled into a U-shaped welding strip by a wire drawing machine from a flat shape, then the metal powder core obtained in step 1.1 is placed in the U-shaped welding strip, then the opening side of the U-shaped welding strip is pressed to cover the metal powder core, then the U-shaped welding strip is rolled through the O-shaped rolling to close the lap O-shaped welding wire, then the lap O-shaped welding wire is drawn to reduce the diameter, and then the surface impurities and oil stains of the welding wire are removed with cotton cloth dipped in acetone to obtain a metal powder core welding wire for the transition layer.

[0084] Step 1.2, the raw materials are mixed as follows: the weighed raw material powder is poured into a vibrating powder mixer and vibrated at a frequency of 2000 times / min for 90 min; in step 1.2, the raw materials are dried in a vacuum tube furnace, specifically, 99.9% Ar gas is introduced into the vacuum tube furnace, the drying temperature is 200°C, and the drying time is 90 min;

[0085] Step 2, the metal powder core welding wire prepared in step 1 is placed in the wire feeding mechanism of the welding robot to perform arc cladding on the surface of the fan impeller bearing and cooling, during welding, gas shielded arc welding is adopted, the protective gas is composed of 98% Ar gas and 2% CO2 gas according to mass percentage, the welding current is 170 A, the welding voltage is 17 V, the amplitude is 8 mm, the welding speed is 0.30 m / min, multi-pass deposition is adopted, the overlap rate of the last pass cladding and the previous pass is 40%, and the required transition layer is obtained after surfacing;

[0086] Step 3, the solid core TC4 welding wire is placed in the wire feeding mechanism of the welding robot, gas shielded arc welding is adopted, the protective gas is 99.9% Ar gas, arc cladding is directly performed on the transition layer prepared in step 2 and cooling, the welding current is 120 A, the welding voltage is 12 V, the amplitude is 0 mm, the welding speed is 0.7 m / min, multi-pass deposition is adopted, the overlap rate of the last pass cladding and the previous pass is 40%, the TC4 layer is obtained after surfacing, then the surface of the TC4 layer obtained by arc cladding is subjected to laser remelting and cooling, the laser power is 140 W, the spot diameter is 120 μm, the scanning speed is 0.9 m / s, the protective gas is 99.9% Ar gas, the surface modification layer is obtained, and the modified structure of the fan impeller bearing surface is obtained.

Claims

1. A modification structure for a bearing surface of a fan impeller shaft, characterized by, The transition layer is prepared on the surface of the fan impeller bearing by arc cladding, and a TC4 layer is prepared on the transition layer by arc cladding and laser remelting; The metal cored welding wire used in the preparation of the transition layer is composed of the following raw material components in percentage by mass: 75%-80% of Inconel 625 nickel-based alloy skin and 20%-25% of metal cored powder, and the sum of the above component percentages is 100%; the metal cored powder is composed of the following raw material components in percentage by mass: 63-65% of nickel powder, 20-23% of chromium powder, 3-4% of niobium powder, 3-5% of molybdenum powder, 3-5% of iron powder, 0.5-1% of titanium powder, 0.5-1% of aluminum powder, 0.5-1% of boron nitride, 0.5-1% of silicon powder, 0.1-0.3% of graphite, 0.2-0.3% of cerium oxide, and the sum of the above component percentages is 100%.

2. A method for modifying the surface of a bearing of a fan impeller, characterized in that, The modified structure for the surface of the fan impeller bearing is prepared according to the following steps: Step 1, prepare the metal cored welding wire for the transition layer; Step 2, place the metal cored welding wire prepared in step 1 into the wire feeding mechanism of the welding robot to perform arc cladding on the surface of the fan impeller bearing and cool it down, and the desired transition layer is obtained after the surfacing is completed; Step 3, place the solid TC4 welding wire into the wire feeding mechanism of the welding robot to directly perform arc cladding on the transition layer prepared in step 2 and cool it down, and the TC4 layer is obtained after the surfacing is completed, then the surface of the TC4 layer obtained by arc cladding is subjected to laser remelting and cooling to obtain the surface modification layer, thereby obtaining the modified structure for the surface of the fan impeller bearing.

3. The method for modifying a bearing surface of an impeller shaft of a fan according to claim 2, wherein, The step 1 is implemented according to the following steps: Step 1.1, weigh the following raw material components in percentage by mass: 63-65% of nickel powder, 20-23% of chromium powder, 3-4% of niobium powder, 3-5% of molybdenum powder, 3-5% of iron powder, 0.5-1% of titanium powder, 0.5-1% of aluminum powder, 0.5-1% of boron nitride, 0.5-1% of silicon powder, 0.1-0.3% of graphite, and 0.2-0.3% of cerium oxide, and the sum of the above component percentages is 100%; Step 1.2, mix the raw materials weighed in step 1.1 uniformly, place them in a vacuum tube furnace for heating, heat preservation and drying, and cool them down to room temperature to obtain the metal cored powder; Step 1.3, roll the Inconel 625 nickel-based alloy skin into a U-shaped welding strip through a wire drawing machine, then place the metal cored powder obtained in step 1.1 into the U-shaped welding strip, then press the opening side of the U-shaped welding strip to cover the metal cored powder, then roll the U-shaped welding strip through an O-shaped rolling to close it into a lap O-shaped welding wire, then reduce the diameter of the lap O-shaped welding wire by drawing, then remove the impurities and oil stains on the surface of the welding wire with cotton cloth dipped in acetone, and the metal cored welding wire for the transition layer is prepared.

4. The method for modifying a bearing surface of an impeller shaft of a fan according to claim 3, wherein The raw material mixing in step 1.2 is specifically: pouring the weighed raw material powder into a vibrating powder mixer to mix at a vibration frequency of 1500-2000 times / min for 60-90 min; and the vacuum tube furnace heating and holding drying in step 1.2 is specifically: introducing 99.9% Ar gas into the vacuum tube furnace, the drying temperature is 150-200 DEG C, and the drying time is 60-90 min.

5. The method for modifying the bearing surface of an impeller shaft of a fan according to any one of claims 2 to 4, characterized in that, In the arc cladding process for preparing the transition layer in step 2, shielded metal arc welding is adopted, and the protective gas is composed of 98% Ar gas and 2% CO2 gas by mass percentage.

6. The method for modifying a bearing surface of an impeller shaft of a fan according to any one of claims 2 to 4, characterized in that, In the arc cladding process for preparing the transition layer in step 2: the welding current is 165-170 A, the welding voltage is 17 V, the swing is 8 mm, and the welding speed is 0.25-0.30 m / min.

7. The method for modifying a bearing surface of an impeller shaft of a fan according to claim 6, wherein The welding mode of the transition layer prepared in step 2 adopts multi-pass deposition, and the overlap rate of the last pass cladding and the previous pass is 40%.

8. The method for modifying a bearing surface of an impeller shaft of a fan according to claim 6, wherein In the arc cladding process of the solid core TC4 welding wire in step 3, shielded metal arc welding is adopted, and the protective gas is 99.9% Ar gas; The welding parameters of the arc cladding process of the solid core TC4 welding wire in step 3 are: the welding current is 115-120 A, the welding voltage is 11-12 V, the swing is 0 mm, and the welding speed is 0.7 m / min; The welding mode of the arc cladding process of the solid core TC4 welding wire in step 3 adopts multi-pass deposition, and the overlap rate of the last pass cladding and the previous pass is 40%.

9. The method for modifying a bearing surface of an impeller shaft of a fan according to claim 8, wherein, The process parameters of the laser remelting in step 3 are: the laser power is 100-140 W, the spot diameter is 80-120 μm, the scanning speed is 0.9 m / s, and the protective gas is 99.9% Ar gas.

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