Fe-Cr-Mo series damping alloy powder and preparation method thereof and damping alloy

Abstract

The present invention relates to the field of additive manufacturing technology, and in particular, to a Fe-Cr-Mo damping alloy powder, a preparation method thereof, and a damping alloy. The alloy powder includes, by weight percentage, Cr 15.5-16.5%, Mo 2-3%, Mn 0.3-1.5%, Si 0.3-1.5%, Ni 1-2%, Cu 0.2-0.3%, Nb 0-0.2%, Ti 0-0.2%, Al 0-0.1%, rare earth elements 0-0.3%, and the remainder is Fe and other unavoidable impurity elements, and the content of impurity elements is less than 0.01%, wherein Nb, Ti, Al or rare earth elements are greater than 0. The Fe-Cr-Mo damping alloy powder of the present invention has high sphericity, low oxygen content, good fluidity, and has broad application prospects in the fields of additive manufacturing and vibration reduction and noise reduction components.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a Fe-Cr-Mo series damping alloy powder, a preparation method thereof, and a damping alloy. Background Art

[0002] The progress of modern science and technology has promoted the improvement of the power and operating speed of mechanical equipment, but it has also brought serious vibration and noise problems. These problems not only affect the accuracy of instruments and meters, but also have an adverse effect on the service life of mechanical equipment. According to statistics, in the machinery manufacturing industry, about 80% of accidents and equipment damage are caused by resonance. Therefore, in the market competition of mechanical products, the vibration and noise levels have become an important factor that cannot be ignored. Damping alloys are a type of alloy that has the strength that structural materials should have. They can effectively convert vibration energy into heat energy through their own structure and consume it quickly to achieve the effect of vibration reduction and noise reduction. It is a novel functional structural material that mainly absorbs external vibration energy through various damping mechanisms inside the material and irreversibly converts it into heat energy for dissipation.

[0003] Among many damping alloys, Fe-Cr-Mo damping alloys have attracted widespread attention due to their excellent mechanical properties, damping properties and corrosion resistance. This type of alloy is ferromagnetic and mainly consumes vibration energy through the movement of internal magnetic domains, thereby producing a damping effect. The matrix of this alloy is single-phase ferrite with a coarse grain structure. It does not undergo solid-state phase transformation during traditional heat treatment, and it is difficult to improve mechanical properties by conventional methods by refining the grains. The preparation of traditional Fe-Cr-Mo damping alloys mostly uses casting and forging processes, which makes it difficult to form complex structural components.

[0004] In recent years, additive manufacturing technology has developed rapidly. This technology uses the method of stacking raw materials layer by layer. Compared with traditional equal-material manufacturing and subtractive manufacturing technologies, it significantly reduces the difficulty of forming complex structural components without the need for molds. Using additive manufacturing technology to manufacture complex lattice structures can effectively combine the material properties of damping alloys with structural advantages, thereby enhancing the vibration reduction effect. In addition, the powder preparation and additive manufacturing forming process are rapid solidification, which can significantly refine the grain size of Fe-Cr-Mo damping alloys, which helps to improve their mechanical properties and damping properties. Compared with other powder making methods, vacuum induction melting gas atomization (VIGA) has become the main preparation method for metal powders for additive manufacturing at home and abroad with its advantages of lower powder making cost, high efficiency and large output.

[0005] The melting point of Fe-Cr-Mo damping alloy is high (1450~1550℃), which requires that the melt must have sufficient superheat during the gas atomization powder making process to ensure excellent fluidity and stability of the powder making process. However, the traditional VIGA process uses a tundish for operation, and the melt loses heat during the pouring process, so a higher melt superheat (300~500℃) and enhanced insulation capacity of the tundish are required. Excessive superheat will cause alloy element burnout, increase the powder solidification time, and thus reduce the sphericity of the powder. At the same time, the insulation and heating measures of the tundish make the process complicated and increase the cost of powder preparation. In addition, due to the high chromium and low nickel chemical composition characteristics of Fe-Cr-Mo damping alloy, the alloy is easy to inhale during the smelting and atomization process, so that interstitial elements such as N and O exist in the form of second phase particles, pinning the magnetic domain to move, affecting the damping performance of the alloy. Therefore, developing a Fe-Cr-Mo damping alloy powder with low oxygen content, good sphericity and high powder yield suitable for additive manufacturing has important practical value and research significance. Summary of the invention

[0006] To solve at least one problem in the background technology, the present invention provides a Fe-Cr-Mo series damping alloy powder, a preparation method thereof and a damping alloy.

[0007] According to a first aspect of the present invention, the present invention provides a Fe-Cr-Mo damping alloy powder, which comprises, by weight percentage:

[0008] Cr 15.5-16.5%, Mo 2-3%, Mn 0.3-1.5%, Si 0.3-1.5%, Ni 1-2%, Cu0.2-0.3%, Nb 0-0.2%, Ti 0-0.2%, Al 0-0.1%, rare earth elements 0-0.3%, the balance is Fe and other unavoidable impurity elements, the content of the impurity elements is less than 0.01%, of which Nb, Ti, Al or rare earth elements are greater than 0;

[0009] The particle size of the alloy powder particles is 15 to 105 μm;

[0010] The base phase in the alloy powder particles is ferrite, and the strengthening phase is second phase particles formed by Nb, Ti, Al and rare earth elements and C, N and O elements among the impurity elements. The ferrite and the second phase particles are in a coherent relationship or a semi-coherent relationship.

[0011] According to one embodiment of the present invention, the rare earth element includes Y, Ce or La.

[0012] According to one embodiment of the present invention, the oxygen content of the damping alloy powder is ≤374ppm, the sphericity is ≥92%, the Hall flow rate is ≤16.8s / 50g, and the tap density is ≥5.16g / cm 3 .

[0013] According to a second aspect of the present invention, the present invention provides a method for preparing Fe-Cr-Mo series damping alloy powder, comprising the following steps:

[0014] After the master alloy raw material containing the above-mentioned Fe-Cr-Mo series damping alloy powder elements is smelted to form a melt, the melt flows out through a guide pipe for atomization;

[0015] When the molten liquid flows out through the flow guide tube for atomization, the pressure in the smelting chamber is higher than the pressure in the atomization chamber;

[0016] During the outflow of the molten liquid, the molten liquid contacts with the atomizing gas, and the molten liquid forms droplets under the impact of the atomizing gas. The droplets are cooled and solidified during the flight to form spherical particles and sub-spherical particles.

[0017] The particles are collected and sieved to obtain Fe-Cr-Mo damping alloy powder having a ferrite matrix and second phase particles formed by the reaction of Nb, Ti, Al and rare earth elements in the master alloy raw material with C, N and O.

[0018] According to one embodiment of the present invention, the smelting comprises: in a smelting environment with a vacuum degree of ≤0.01 Pa, filling an inert gas to a first smelting chamber pressure; at a first power and a first smelting temperature, raising the first smelting chamber pressure to a second smelting chamber pressure, and melting the master alloy raw material to obtain a first molten liquid;

[0019] After raising the first melting temperature to a second temperature, maintaining the temperature at the second temperature for a first time to obtain a second molten liquid;

[0020] After the second melting temperature is raised to the atomization temperature, the atomization temperature is maintained for a second time, the second time being shorter than the first time, to obtain a third molten liquid, and the third molten liquid flows out through the guide pipe for atomization;

[0021] When the third molten liquid flows out for atomization, the pressure of the second smelting chamber is increased to the pressure of the third smelting chamber, and the pressure of the third smelting chamber is higher than the pressure of the atomization chamber.

[0022] According to one embodiment of the present invention, the atomization includes: the gas pressure in the atomization chamber is 3 to 6 MPa, and the ratio of the flow rate of the atomization gas to the flow rate of the melt flowing out for atomization is 4:1 to 10:1.

[0023] According to one embodiment of the present invention, the first smelting temperature is 1450-1550°C;

[0024] The second smelting temperature is 1550-1600°C;

[0025] The atomization temperature is 1650-1750°C.

[0026] According to one embodiment of the present invention, the pressure of the first smelting chamber is equal to the atmospheric pressure;

[0027] The difference between the pressure of the second smelting chamber and the atmospheric pressure is 2-5 kPa;

[0028] The difference between the pressure of the third smelting chamber and the pressure of the atomizing chamber is 20-40 kPa;

[0029] When the third molten liquid flows out to be atomized, the second power is reduced at a first speed, and the first speed is 100-200 W / s.

[0030] According to an embodiment of the present invention, the superheat degree of the third molten liquid for the atomization is 200°C to 300°C.

[0031] According to a third aspect of the present invention, the present invention provides a damping alloy, which is prepared using the Fe-Cr-Mo series damping alloy powder as described above, wherein the grains in the damping alloy are equiaxed crystals with a size of 10 to 20 μm.

[0032] The present invention has the following beneficial effects:

[0033] 1. The present invention improves the fluidity of low superheat melt by optimizing the alloy powder composition, thereby ensuring the efficient atomization process of the high melting point Fe-Cr-Mo damping alloy.

[0034] 2. The present invention adopts the method of melting the master alloy raw material into a molten liquid, and then the molten liquid directly flows into the atomization chamber for atomization without using a tundish, which simplifies the process flow, reduces the production cost, and avoids the drop in the superheat of the melt during the pouring process. By coordinating the power supply power drop during the atomization process, the superheat of the melt is kept within the preset range, so that the superheat is only 200-300°C.

[0035] 3. The Fe-Cr-Mo damping alloy powder prepared by the present invention has high sphericity (≥92%), low oxygen content (≤380ppm) and good fluidity (≤17s / 50g), providing high-performance, low-cost iron-based damping alloy spherical powder for additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 shows the particle size distribution curve of the damping alloy powder of Example 1 of the present invention;

[0037] Figure 2 The macroscopic morphology of the damping alloy powder of Example 1 of the present invention is shown;

[0038] Figure 3 An alloy test block image printed by the damping alloy powder of Example 1 of the present invention is shown;

[0039] Figure 4 The macroscopic morphology of the damping alloy powder of Comparative Example 2 of the present invention is shown;

[0040] Figure 5 The macroscopic morphology of the damping alloy powder of Example 2 of the present invention is shown;

[0041] Figure 6 A damping alloy test block image printed by the damping alloy powder of Example 1 or Example 2 of the present invention is shown;

[0042] Figure 7 The damping alloy microstructure diagram printed by the damping alloy powder of Example 1 and Example 2 of the present invention is shown. DETAILED DESCRIPTION

[0043] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0044] According to the first aspect of the present invention, this embodiment discloses a Fe-Cr-Mo damping alloy powder, such as Figure 1 As shown, by weight percentage, it includes:

[0045] Cr 15.5-16.5%, Mo 2-3%, Mn 0.3-1.5%, Si 0.3-1.5%, Ni 1-2%, Cu0.2-0.3%, Nb 0-0.2%, Ti 0-0.2%, Al 0-0.1%, rare earth elements 0-0.3%, the balance is Fe and other unavoidable impurity elements, the content of the impurity elements is less than 0.01%, of which Ti, Al or rare earth elements are greater than 0;

[0046] The particle size of the alloy powder particles is 15 to 105 μm;

[0047] The base phase in the alloy powder particles is ferrite, and the strengthening phase is second phase particles formed by Nb, Ti, Al and rare earth elements and C, N and O elements among the impurity elements. The ferrite and the second phase particles are in a coherent relationship or a semi-coherent relationship.

[0048] In this embodiment, through the selection of the components of this embodiment, Nb, Ti, Al, rare earth elements and C, N, O in the impurity elements are combined to form second phase particles of moderate size, and the second phase particles are in a coherent or semi-coherent relationship with the ferrite matrix. The second phase particles act as nucleation particles to refine the grains in the alloy, and as a local internal stress source in the form of weak pinning, the energy consumption of magnetic domain movement is increased, thereby improving the damping performance of the alloy; at the same time, the damage of C, N, O interstitial elements to the alloy performance is reduced. 1-2% Ni is beneficial to provide the strength of the alloy.

[0049] Preferably, Cr 15.51%, Mo 2.03%, Mn 0.37%, Si 0.47%, Ni 1.02%, Cu 0.21%, Nb 0.059%, Ti 0.058%, Al 0.062% and the sum of at least two rare earth elements is 0.022%.

[0050] Preferably, Cr 16.42%, Mo 2.91%, Mn 0.81%, Si 0.86%, Ni 1.88%, Cu 0.27%, Nb 0.18%, Ti 0.14%, Al 0.048% and the sum of at least two rare earth elements is 0.046%.

[0051] Preferably, the particle size of the alloy powder particles is 15 to 53 μm.

[0052] Preferably, the particle size of the alloy powder particles is 45 to 105 μm.

[0053] According to one embodiment of the present invention, the rare earth element includes Y, Ce or La.

[0054] In this embodiment, the selection and amount of rare earth elements are beneficial to controlling the purity of the alloy and improving the damping performance of the alloy.

[0055] Preferably, the rare earth element includes one or more of Y, Ce and La elements.

[0056] According to one embodiment of the present invention, the oxygen content of the damping alloy powder is ≤374ppm, the sphericity is ≥92%, the Hall flow rate is ≤16.8s / 50g, and the tap density is ≥5.16g / cm 3 .

[0057] In this embodiment, high-performance, low-cost iron-based damping alloy spherical powder is provided for additive manufacturing.

[0058] Preferably, the damping alloy powder has an oxygen content of 374 ppm, a sphericity of 93%, a Hall flow rate of 16.8 s / 50 g, and a tap density of 5.16 g / cm 3 .

[0059] Preferably, the damping alloy powder has an oxygen content of 341 ppm, a sphericity of 92%, a Hall flow rate of 15.6 s / 50 g, and a tap density of 5.28 g / cm 3 .

[0060] According to the second aspect of the present invention, this embodiment discloses a method for preparing Fe-Cr-Mo damping alloy powder, comprising the following steps:

[0061] After the master alloy raw material containing the Fe-Cr-Mo series damping alloy powder element as claimed in claim 1 is smelted to form a melt, the melt flows out through a guide pipe for atomization;

[0062] When the molten liquid flows out through the flow guide tube for atomization, the pressure in the smelting chamber is higher than the pressure in the atomization chamber;

[0063] During the outflow of the molten liquid, the molten liquid contacts with the atomizing gas, and the molten liquid forms droplets under the impact of the atomizing gas. The droplets are cooled and solidified during the flight to form spherical particles and sub-spherical particles.

[0064] The particles are collected and sieved to obtain Fe-Cr-Mo damping alloy powder having a ferrite matrix and second phase particles formed by the reaction of Nb, Ti, Al and rare earth elements in the master alloy raw material with C, N and O.

[0065] In this embodiment, after the mother alloy raw material is melted into molten liquid, the molten liquid directly flows into the atomization chamber for atomization without using a tundish, which simplifies the process flow, reduces production costs, and avoids the drop in superheat of the melt during the pouring process.

[0066] According to one embodiment of the present invention, the smelting comprises: in a smelting environment with a vacuum degree of ≤0.01 Pa, filling an inert gas to a first smelting chamber pressure; at a first power and a first smelting temperature, raising the first smelting chamber pressure to a second smelting chamber pressure, and melting the master alloy raw material to obtain a first molten liquid;

[0067] After raising the first melting temperature to a second temperature, maintaining the temperature at the second temperature for a first time to obtain a second molten liquid;

[0068] After the second melting temperature is raised to the atomization temperature, the atomization temperature is maintained for a second time, the second time being shorter than the first time, to obtain a third molten liquid, and the third molten liquid flows out through the guide pipe for atomization;

[0069] When the third molten liquid flows out for atomization, the pressure of the second smelting chamber is increased to the pressure of the third smelting chamber, and the pressure of the third smelting chamber is higher than the pressure of the atomization chamber.

[0070] In some embodiments, the first time is 8 minutes and the second time is 3 minutes.

[0071] According to one embodiment of the present invention, the atomization includes: the gas pressure in the atomization chamber is 3 to 6 MPa, and the ratio of the flow rate of the atomizing gas to the flow rate of the melt flowing out for atomization is 4:1 to 10:1.

[0072] Preferably, the ratio of the flow rate of the atomizing gas to the flow rate of the melt flowing out for atomization is 8:1.

[0073] Preferably, the ratio of the flow rate of the atomizing gas to the flow rate of the melt flowing out for atomization is 5:1.

[0074] According to one embodiment of the present invention, the first smelting temperature is 1450-1550°C;

[0075] The second smelting temperature is 1550-1600°C;

[0076] The atomization temperature is 1650-1750°C.

[0077] Preferably, the first smelting temperature is 1520°C;

[0078] The second melting temperature is 1550;

[0079] The atomization temperature is 1700°C.

[0080] Preferably, the first smelting temperature is 1530°C;

[0081] The second smelting temperature is 1560°C;

[0082] The atomization temperature is 1660°C.

[0083] According to one embodiment of the present invention, the pressure of the first smelting chamber is equal to the atmospheric pressure;

[0084] The pressure of the second smelting chamber is 2-5 kPa higher than the atmospheric pressure;

[0085] The pressure of the third smelting chamber is 20-40 kPa higher than the pressure of the atomizing chamber;

[0086] When the third molten liquid flows out to be atomized, the first power is reduced at a first speed, and the first speed is 100 to 200 W / s.

[0087] In this embodiment, the atmospheric pressure is 1.013×10 5 Pa. The first power is 40-70kW.

[0088] Preferably, the pressure of the second smelting chamber is 2-5 kPa higher than the atmospheric pressure; and the pressure of the third smelting chamber is 20-40 kPa higher than the pressure of the atomizing chamber.

[0089] Preferably, the pressure of the second smelting chamber is 4 kPa higher than the atmospheric pressure; the pressure of the third smelting chamber is 25 kPa higher than the pressure of the atomizing chamber; the first power is 50 kW, and the first speed is 120 W / s.

[0090] Preferably, the pressure of the second smelting chamber is 3 kPa higher than the atmospheric pressure; the pressure of the third smelting chamber is 40 kPa higher than the pressure of the atomizing chamber; the first power is 55 kW, and the first speed is 160 W / s.

[0091] According to an embodiment of the present invention, the superheat degree of the third molten liquid for the atomization is 200°C to 300°C.

[0092] In some embodiments, the length of the guide tube extending into the atomization environment is 3 to 5 mm, and the inner diameter of the guide tube is 2 to 4.5 mm.

[0093] Preferably, the length of the guide tube extending into the atomization environment is 3.5 mm, and the inner diameter of the guide tube is 3 mm.

[0094] Preferably, the length of the guide tube extending into the atomization environment is 5 mm, and the inner diameter of the guide tube is 4.5 mm.

[0095] In some embodiments, the inert gas and the atomizing gas are high-purity argon gas with a purity of 99.999%. The atomizing gas is high-purity argon gas which can not only achieve the atomization effect, but also protect the atomization process to prevent the alloy powder particles from reacting with other substances.

[0096] According to the third aspect of the present invention, this embodiment discloses a damping alloy, which is prepared by using the above-mentioned Fe-Cr-Mo series damping alloy powder, and the grains in the damping alloy are equiaxed crystals with a size of 10 to 20 μm.

[0097] Example 1

[0098] This embodiment is a preparation method of Fe-Cr-Mo damping alloy powder with a particle size range of 15 to 53 μm and a preparation method thereof. The chemical composition of the alloy powder is Cr 15.51%, Mo 2.03%, Mn 0.37%, Si 0.47%, Ni 1.02%, Cu 0.21%, Nb 0.059%, Ti 0.058%, Al 0.062% and at least two rare earth elements whose sum is 0.022% by weight percentage, and the balance is Fe and unavoidable impurities. The steps are as follows:

[0099] S1: Preliminary preparation, use two crucibles, one large and one small, stacked together, and pour refractory sand into the gap in the middle of the crucible to ensure the strength and stability of the crucible during the smelting process. Drill a hole (diameter 1.2cm) at the bottom of the crucible, insert the guide tube into it, and use refractory mud to fill the gap between the guide tube and the crucible to ensure sealing. Place the crucible in the induction coil in the center of the smelting chamber, and align it with the center of the atomization spray plate, so that the guide tube passes through the center of the nozzle and extends out. The extension length of the guide tube is 3.5mm and the inner diameter is 3mm. Place the temperature measuring thermocouple in the ceramic plug rod, and fix the upper end of the plug rod in the vertical feeding mechanism in the center of the smelting chamber. The lower end of the plug rod is fitted with the upper end of the guide tube through the feeding mechanism at a certain pressure to ensure that the molten alloy will not leak during the smelting process.

[0100] S2: Vacuuming. The master alloy is prepared using a vacuum induction melting furnace (VIM). The master alloy raw materials are sanded to remove the surface oxide scale and placed in a crucible. Close the furnace door, open the mechanical pump and the roughing valve. When the vacuum is evacuated to 800Pa, turn on the Roots pump. When the vacuum is below 1Pa, turn on the diffusion pump. When the vacuum degree reaches below 0.01Pa, turn off the vacuum pump and fill with high-purity argon (purity is 99.999%) until the melting chamber pressure reaches atmospheric pressure.

[0101] S3: Melting, turn on the medium frequency induction power supply, start heating and melting, the first power is 50kW, the melting temperature is 1520℃, and the gas diversion is adjusted to make the melting chamber pressure 4kPa higher than the atmospheric pressure. After the master alloy is melted, continue to heat up and refine, the refining temperature is 1550℃, and the refining time is 8min. After the refining is completed, power is supplied to heat up, and the melt temperature is heated to 1700℃ and kept warm for 3min.

[0102] S4: Atomization, the temperature of the atomization chamber is 1700℃, the plug rod is lifted through the vertical feeding mechanism to make the molten liquid flow out through the guide tube, and the air inlet valve is opened at the same time to adjust the atomization gas pressure to 5MPa. During the atomization process, the gas diversion is adjusted to make the pressure of the smelting chamber 25kPa higher than the pressure of the atomization chamber to ensure the fluidity of the molten liquid under positive pressure and improve the atomization stability. The flow rate of the atomization gas and the flow rate of the molten liquid into the atomization chamber are stabilized at 8:1. As the remaining molten liquid in the crucible decreases, the first power of the medium frequency power supply is lowered to a speed of 120W / s to ensure that the superheat of the molten liquid remains unchanged during the atomization process. The molten liquid is atomized into fine droplets by high-pressure argon gas and cooled and solidified into alloy powder. The powder is stored in the powder collecting tank through the cyclone separation system.

[0103] S5: Powder collection. After atomization, turn off the heating power supply and the air inlet valve. When collecting powder, close the two pneumatic butterfly valves on the powder collecting tank, remove the pneumatic butterfly valve together with the powder collecting tank, and transfer to the vacuum glove box to take out the powder. Under the protection of inert gas, use an explosion-proof vibrating screen to screen the powder. The screening particle size range is 15 to 53μm, and then vacuum seal and package.

[0104] Comparative Example 1

[0105] The difference from Example 1 is that in step S3, the pressure in the smelting chamber is consistent with the atmospheric pressure; in step S4, the pressure in the smelting chamber is consistent with the pressure in the atomization chamber.

[0106] Comparative Example 2

[0107] The difference from Example 1 is that the alloy powder chemistry is fully calculated by weight percentage as Cr 15.3%, O 3.2%, Mn 0.1%, Si 0.2%, Ni 2.2%, Cu 0.1%, Nb 0.3%, Ti 0.4% and Al 0.2%, and the balance is Fe and inevitable impurities.

[0108] Comparative Example 3

[0109] The difference from Example 1 is that in step S1, the extension length of the flow guide tube is 2.5 mm.

[0110] Figure 1 The particle size distribution curve of the Fe-Cr-Mo damping alloy powder obtained by sieving in Example 1 is shown, and the particle size distribution is 15 to 53 μm. Figure 2 This is the overall morphology of the Fe-Cr-Mo damping alloy powder obtained by screening in Example 1 using a scanning electron microscope. It can be seen from the figure that the Fe-Cr-Mo damping alloy powder prepared by the present invention has a smooth surface, excellent sphericity, and a narrow particle size distribution. Table 1 shows the alloy powder particle size distribution and powder yield data of Example 1 and Comparative Examples 1 to 3. The results show that the optimized parameters of Example 1 can produce a powder with a high fine powder yield of 47.8%. Table 2 lists the oxygen content and physical property parameters of the alloy powders of Example 1 and Comparative Examples 1 to 3, showing that the optimized parameters of Example 1 can be used to prepare Fe-Cr-Mo damping alloy powders with a high fine powder yield (47.8%), low oxygen content (374ppm), high sphericity (94%), and excellent fluidity (16.8s / 50g). The particle size distribution is 15 to 53μm, which is suitable for powder bed-based additive manufacturing processes such as SLM (selective laser melting). The prepared powder was used for SLM powder printing and heat treatment. The test block is as follows Figure 3 As shown, the density of the test block reaches more than 99.4% and the damping performance reaches 0.051.

[0111] For Comparative Example 1, the melting chamber pressurization process was not used during the melting and atomization stages, resulting in an increase in oxygen content. Although the fine powder yield was slightly improved, the sphericity and fluidity of the powder were reduced. Figure 4The macroscopic morphology of the damping alloy powder of Comparative Example 2 is presented. In the powder making process of Comparative Example 2, the melt viscosity is high, the fluidity is poor, the sphericity of the obtained powder is low, and the oxygen content is high. In Comparative Example 3, the extended length of the guide tube is increased to 4.5 mm, resulting in an increase in the suction pressure at the end of the guide tube, an increase in the melt flow rate, and a decrease in the gas-liquid ratio, thereby reducing the fine powder recovery rate.

[0112] Table 1 Particle size distribution and powder yield of alloy powder in Example 1 and Comparative Examples 1 to 3

[0113]

[0114]

[0115] Table 2 Oxygen content and physical properties of alloy powders in Example 1 and Comparative Examples 1 to 3

[0116]

[0117] Example 2

[0118] This embodiment is a preparation method of Fe-Cr-Mo damping alloy powder with a particle size range of 45 to 105 μm and a preparation method thereof. The chemical composition of the alloy powder is Cr 16.42%, Mo 2.91%, Mn 0.81%, Si 0.86%, Ni 1.88%, Cu 0.27%, Nb 0.18%, Ti 0.14%, Al 0.048% and at least two rare earth elements whose sum is 0.046% by weight percentage, and the balance is Fe and unavoidable impurities. The steps are as follows:

[0119] S1: Preliminary preparation, use two crucibles, one large and one small, stacked together, and pour refractory sand into the gap in the middle of the crucible to ensure the strength and stability of the crucible during the smelting process. Drill a hole (1.4cm in diameter) in the lower part of the crucible, insert the guide tube into it, and use refractory mud to fill the gap between the guide tube and the crucible to ensure sealing. Place the crucible in the induction coil in the center of the smelting chamber, and align it with the center of the atomization spray plate, so that the guide tube passes through the center of the nozzle and extends out. The extension length of the guide tube is 5mm and the inner diameter is 4.5mm. Place the temperature measuring thermocouple in the ceramic plug rod, and fix the upper end of the plug rod in the vertical feeding mechanism in the center of the smelting chamber. The lower end of the plug rod is fitted with the upper end of the guide tube through the feeding mechanism at a certain pressure to ensure that the molten alloy will not leak during the smelting process.

[0120] S2: Vacuuming. The master alloy is prepared using a vacuum induction melting furnace (VIM). The master alloy raw materials are sanded to remove the surface oxide scale and placed in a crucible. Close the furnace door, open the mechanical pump and the roughing valve. When the vacuum is evacuated to 800Pa, turn on the Roots pump. When the vacuum is below 1Pa, turn on the diffusion pump. When the vacuum degree reaches below 0.01Pa, turn off the vacuum pump and fill with high-purity argon (purity is 99.999%) until the melting chamber pressure reaches atmospheric pressure.

[0121] S3: Melting. Turn on the medium frequency induction power supply and start heating and melting. The first power is 55kW, the melting temperature is 1530℃, and the gas diversion is adjusted so that the pressure in the melting chamber is 3kPa higher than the atmospheric pressure. After the master alloy is melted, continue to heat and refine, the refining temperature is 1560℃, and the refining time is 8min. After the refining is completed, power is supplied to heat up, and the melt temperature is heated to 1660℃ and kept warm for 3min.

[0122] S4: Atomization, lift the plug rod through the vertical feeding mechanism to make the molten liquid flow out through the guide tube, and open the air inlet valve at the same time to adjust the atomizing gas pressure to 4MPa. During the atomization process, adjust the gas diversion so that the pressure of the smelting chamber is 40kPa higher than the pressure of the atomizing chamber to ensure the fluidity of the molten liquid under positive pressure and improve the atomization stability. The flow rate of the atomizing gas and the flow rate of the molten liquid into the atomizing chamber are stabilized at 5:1. As the remaining molten liquid in the crucible decreases, the first power of the medium frequency power supply is lowered to 160W / s to ensure that the superheat of the molten liquid remains unchanged during the atomization process. The molten liquid is atomized into fine droplets by high-pressure argon gas and cooled and solidified into alloy powder. The powder is stored in the powder collecting tank through the cyclone separation system.

[0123] S5: Powder collection. After atomization, turn off the heating power supply and the air inlet valve. When collecting powder, close the two pneumatic butterfly valves on the powder collecting tank, remove the pneumatic butterfly valve together with the powder collecting tank, and transfer to the vacuum glove box to take out the powder. Under the protection of inert gas, use an explosion-proof vibrating screen to screen the powder. The screening particle size range is 45-105μm, and then vacuum seal the package.

[0124] Comparative Example 4

[0125] The difference from Example 2 is that, in step S4, as the remaining melt in the crucible decreases, the first power of the medium frequency power supply remains unchanged.

[0126] Comparative Example 5

[0127] The difference from Example 2 is that in step S1, the inner diameter of the flow guide tube is 6 mm.

[0128] Comparative Example 6

[0129] The difference from Example 2 is that in step S3, the melt temperature is 1600°C.

[0130] Figure 5 The scanning electron microscope morphology of the Fe-Cr-Mo damping alloy powder obtained by screening in Example 2 is shown, and its particle size distribution range is 45 to 105 microns. It can be observed from the figure that the Fe-Cr-Mo damping alloy powder prepared by the present invention has a high sphericity and a low proportion of irregular powder. Table 3 lists in detail the particle size distribution of the alloy powders of Example 2 and Comparative Examples 4 to 6 and the yield of 45 to 105 μm powder. As shown in Table 3, Example 2 prepared a powder with a high yield of 56.6% by optimizing the parameters. Table 4 further shows the oxygen content and other physical property parameters of the alloy powders of Example 2 and Comparative Examples 4 to 6. The results show that the Fe-Cr-Mo damping alloy powder with an oxygen content as low as 341 ppm, a sphericity as high as 92%, and excellent fluidity (15.6s / 50g) can be prepared by using the optimized parameters of Example 2. The particle size distribution is 45 to 105 microns, which is suitable for additive manufacturing processes based on coaxial powder feeding such as laser molten deposition (LMD).

[0131] In Comparative Example 4, the power supply power remained unchanged during the atomization stage, resulting in an increase in the superheat of the remaining melt in the crucible, an increase in the oxygen content, and an extension of the spheroidization and solidification time of the droplets, which reduced the sphericity and fluidity of the powder. Comparative Example 5 used a flow guide tube with an inner diameter of 6 mm, which increased the melt flow rate and reduced the gas-liquid ratio. As a result, the prepared powder had a larger particle size and a significantly reduced powder yield. In Comparative Example 6, the atomization temperature was reduced to 1600°C, and the superheat of the melt was insufficient, resulting in the melt solidifying in the flow guide tube and the atomization process being interrupted.

[0132] Table 3 Particle size distribution and powder yield of gold powder in Example 2 and Comparative Examples 4 to 6

[0133]

[0134] Table 4 Oxygen content and physical properties of alloy powders in Example 2 and Comparative Examples 4 to 6

[0135]

[0136] Example 3

[0137] The powder prepared in Example 1 or Example 2 was used for LMD powder feeding printing to obtain a damping alloy test block such as Figure 6 The metallographic structure of the damping alloy test block is shown in Figure 7 As shown in the figure, the white part is the grain, the gray part is the grain boundary, and the metallographic structure is dispersed with fine equiaxed crystals with a size of 10 to 20 μm, which act as local internal stress sources in the form of weak pinning, thereby increasing the energy consumption of magnetic domain movement and thus improving the damping performance of the alloy. The density of the damping alloy test block reaches more than 99.5%, and the damping performance reaches 0.047.

[0138] Compared with the traditional VIGA system using a tundish, the present invention adopts a plug rod direct pouring system, which simplifies the process flow, reduces production costs, and avoids the drop in superheat of the melt during pouring. By coordinating the power supply slow-down during the atomization process, the superheat of the melt is maintained within a preset range, so that the superheat is only 100 to 200°C. In addition, by optimizing the alloy powder composition, the fluidity of the low superheat melt is improved, ensuring the efficient atomization process of the high melting point Fe-Cr-Mo damping alloy.

[0139] The present invention effectively suppresses the loss of easily burnt elements during the smelting process by precisely controlling the gas partial pressure in the smelting chamber, and maintains the gas-liquid ratio in the atomization process within a preset range, thereby reducing the particle size distribution width of the powder and increasing the powder yield to 56.6%. The entire process from smelting, powder making to screening and storage is carried out under vacuum or inert gas protection, ensuring that the oxygen content of the Fe-Cr-Mo damping alloy powder is strictly controlled during smelting, atomization and storage.

[0140] The present invention significantly improves the stability and powder yield of the Fe-Cr-Mo damping alloy powder making process by adjusting the alloy composition and co-optimizing the powder making process parameters. The Fe-Cr-Mo damping alloy powder manufactured by the present invention has high sphericity (≥92%), low oxygen content (≤380ppm) and good fluidity (≤17s / 50g), providing high-performance, low-cost iron-based damping alloy spherical powder for additive manufacturing.

[0141] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made thereto in form and detail without departing from the scope of the present disclosure.

Claims

1. A Fe-Cr-Mo damping alloy powder, characterized in that: The percentage by weight includes: Cr 15.5-16.5%, Mo 2-3%, Mn 0.3-1.5%, Si 0.3-1.5%, Ni 1-2%, Cu0.2-0.3%, Nb 0-0.2%, Ti 0-0.2%, Al 0-0.1%, rare earth elements 0-0.3%, the balance is Fe and other unavoidable impurity elements, the content of the impurity elements is less than 0.01%, of which Nb, Ti, Al or rare earth elements are greater than 0; The particle size of the alloy powder particles is 15 to 105 μm; The base phase in the alloy powder particles is ferrite, and the strengthening phase is second phase particles formed by Nb, Ti, Al and rare earth elements and C, N and O elements among the impurity elements. The ferrite and the second phase particles are in a coherent relationship or a semi-coherent relationship.

2. The Fe-Cr-Mo damping alloy powder according to claim 1, characterized in that: The rare earth element includes Y, Ce or La.

3. The Fe-Cr-Mo damping alloy powder according to claim 1, characterized in that: The damping alloy powder has an oxygen content of ≤374ppm, a sphericity of ≥92%, a Hall flow rate of ≤16.8s / 50g, and a tap density of ≥5.16g / cm 3 .

4. A method for preparing Fe-Cr-Mo damping alloy powder, characterized in that: The steps include: After the master alloy raw material containing the Fe-Cr-Mo series damping alloy powder as claimed in any one of claims 1 to 3 is smelted to form a molten liquid, the molten liquid flows out through a guide pipe for atomization; When the molten liquid flows out through the flow guide tube for atomization, the pressure in the smelting chamber is higher than the pressure in the atomization chamber; During the outflow of the molten liquid, the molten liquid contacts with the atomizing gas, and the molten liquid forms droplets under the impact of the atomizing gas. The droplets are cooled and solidified during the flight to form spherical particles and sub-spherical particles. The particles are collected and sieved to obtain Fe-Cr-Mo damping alloy powder having a ferrite matrix and second phase particles formed by the reaction of Ti, Al and rare earth elements in the master alloy raw material with C, N and O.

5. The method for preparing Fe-Cr-Mo damping alloy powder according to claim 4, characterized in that: The smelting comprises: in a smelting environment with a vacuum degree of ≤0.01Pa, filling an inert gas to a first smelting chamber pressure; at a first power and a first smelting temperature, raising the first smelting chamber pressure to a second smelting chamber pressure, and melting the master alloy raw material to obtain a first molten liquid; After raising the first melting temperature to a second temperature, maintaining the temperature at the second temperature for a first time to obtain a second molten liquid; After the second melting temperature is raised to the atomization temperature, the atomization temperature is maintained for a second time, the second time being shorter than the first time, to obtain a third molten liquid, and the third molten liquid flows out through the guide pipe for atomization; When the third molten liquid flows out to be atomized, the pressure of the second smelting chamber is increased to the pressure of the third smelting chamber, and the pressure of the third smelting chamber is higher than the pressure of the atomization chamber.

6. The method for preparing Fe-Cr-Mo damping alloy powder according to claim 5, characterized in that: The atomization includes: the atomization gas pressure is 3-6Mpa, and the flow rate ratio of the atomization gas to the flow rate of the melt flowing out for atomization is 4:1-10:

1.

7. The method for preparing Fe-Cr-Mo damping alloy powder according to claim 5, characterized in that: The first smelting temperature is 1450-1550°C; The second smelting temperature is 1550-1600°C; The atomization temperature is 1650-1750°C.

8. The method for preparing Fe-Cr-Mo damping alloy powder according to claim 5, characterized in that: The pressure of the first smelting chamber is equal to the atmospheric pressure; The difference between the pressure of the second smelting chamber and the atmospheric pressure is 2-5 kPa; The difference between the pressure of the third smelting chamber and the pressure of the atomizing chamber is 20-40 kPa; When the third molten liquid flows out to be atomized, the first power is reduced at a first speed, and the first speed is 100 to 200 W / s.

9. The method for preparing Fe-Cr-Mo damping alloy powder according to claim 5, characterized in that: The third molten metal subjected to the atomization has a superheat degree of 200°C to 300°C.

10. A damping alloy, characterized in that: The damping alloy is prepared by using a Fe-Cr-Mo series damping alloy powder as described in any one of claims 1 to 3, wherein the grains in the damping alloy are equiaxed crystals with a size of 10 to 20 μm.

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