CN103240412A - Method for preparing powder super-alloy by near net shape - Google Patents

Abstract

A method for preparing powdered superalloys in a near-net shape. First, vacuum smelting and jet milling techniques are used to prepare high-purity master alloy powders, and then the master alloy powders are mixed with fine-grained metal powders (such as carbonyl nickel powder, carbonyl iron powder, reduced tungsten powder, reduced molybdenum powder, etc.) to obtain mixed powder. The mixed powder and the paraffin-based binder are pre-mixed evenly, and the feed with uniform rheological properties is obtained through kneading, and the feed is formed on an injection molding machine to obtain a complex-shaped green body. Solvent degreasing, heating and degreasing process is used to remove the binder for the complex shape body, and the degreased body is sintered in a vacuum atmosphere. alloy parts. This invention significantly reduces the cost of raw material powder and process energy consumption, and the prepared superalloy is close to full density, uniform in structure and excellent in comprehensive mechanical properties.

Description

A method for preparing powder superalloy in near-net shape

technical field

The invention belongs to the technical field of powder injection molding, and particularly provides a method for preparing a powder superalloy in a near-net shape.

Background technique

Powder superalloys have good high-temperature strength, oxidation and corrosion resistance, excellent fatigue and creep resistance, fracture performance and structural stability, and are irreplaceable key materials for many modern defense equipment and national economic construction. Powder superalloys have a high degree of alloying, and traditional casting products often have serious composition segregation and uneven structure, so that their performance cannot be fully exerted. Compared with cast superalloys, powder superalloys have the advantages of uniform structure composition, no macro segregation, etc., and their comprehensive properties are more excellent. The traditional process of preparing powder superalloy parts generally uses the process of "atomized alloy powder-hot isostatic pressing (hot extrusion)-isothermal forging-machining". When manufacturing parts with complex shapes (especially small and complex parts), it is often More machining processes are required, the utilization rate of raw materials is low, and the machining performance of superalloys is poor, and the manufacturing cost of parts is very high, which limits the wide application of powder superalloys. Powder injection molding has unique advantages in mass production of small parts with three-dimensional complex shapes, such as hot-end parts in locomotive engine turbochargers (such as supercharger turbines, regulating blades, etc.), and small-sized components in aeroengines. High temperature parts such as small high pressure blades, honeycomb turbine seals, lock nuts and adjustment rods. However, until now, injection molding powder superalloy products have not been widely used in industrial applications. There are two main reasons: first, it is difficult to sinter and densify the product, the required sintering temperature is high, and the sintering deformation is often large. The second is that powder injection molding often needs to use fine powder with a small particle size (average particle size ~10μm), while the existing alloy powder production technology has low yield and high manufacturing cost, especially high quality (low Oxygen content, less non-metallic inclusions) the source of fine superalloy powder is extremely limited. From the perspective of reducing the cost of raw material powders, the invention alloys by adding fine intermediate alloy powders, and prepares superalloy parts with complex shapes by using injection molding technology.

Contents of the invention

The object of the present invention is to provide a method for preparing superalloy parts with complex shapes by using injection molding technology. Using the mixed powder of master alloy powder and fine pure metal powder (such as carbonyl nickel powder, carbonyl iron powder, reduced tungsten powder, reduced molybdenum powder, etc.) Gradients are used to increase the driving potential of atom migration during sintering, and to reduce the sintering temperature, so that the sintering process can be carried out under the condition that there is no liquid phase or only a small amount of liquid phase appears. This method helps to solve the problem of product sintering deformation, and can also significantly reduce the cost of raw material powder and process energy consumption.

In the present invention, the high-purity master alloy powder is firstly prepared by vacuum smelting and jet crushing technology, and then fine-grained metal powder (carbonyl nickel powder, carbonyl iron powder, ultrafine cobalt powder, reduced tungsten powder , reduced molybdenum powder, etc.) are mixed with the master alloy powder to obtain a mixed powder with uniform composition distribution, suitable bulk density and fluidity, and large lattice distortion. Next, the mixed powder and the paraffin-based binder are pre-mixed evenly, and the mixed powder is kneaded to obtain a feed material with uniform rheological properties, and the feed material is formed on an injection molding machine to obtain the required complex shape green body. The binder is removed by solvent degreasing + thermal degreasing, and the degreased body is sintered in a vacuum atmosphere. The sintered body is further densified by hot isostatic pressing without a jacket, and finally solid solution and aging treatment are performed to obtain a superalloy with a complex shape. Parts, preparation process as shown in Figure 1, the specific process steps are:

1. Raw material powder preparation: Design the master alloy according to the type and content of alloy elements in the target superalloy. The content of matrix elements (Fe, Ni or Co) in the master alloy is 25-40wt.%, and the rest are active elements (such as Cr, Ti, Al, Ta, Nb, Zr, Hf, B, Re and C), and the mass ratio of various active elements is consistent with the mass ratio of each element in the target superalloy. The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. Next, the master alloy ingot is turned into chips, and the chips are broken into fine particles on a high-speed pulverizer. The fine particles are further refined by airflow crushing, the gas pressure is 3~8MPa, and the frequency of the sorting wheel is 40~60Hz, and the intermediate alloy powder with an average particle size of ≤10μm is obtained. In a high-purity Ar atmosphere (99.999%), fine-grained (2-10μm) metal powders (such as carbonyl nickel powder, carbonyl iron powder, ultra-fine cobalt powder, reduced tungsten powder, reduced molybdenum powder, etc.) Perform high-energy ball milling to obtain mixed powder;

The target superalloys are various standard brands of iron-based superalloys (such as K213, GH2036, GH2038 or GH2132, etc.), nickel-based superalloys (such as K418, René104, GH4049 or GH4169, etc.), cobalt-based superalloys (Mar -M509, FSX-414, Mar-M302 or Haynes25, etc.), or non-standard alloys designed according to actual working conditions;

2. Mixing: mixing powder with a particle size of less than 20 μm and a paraffin-based binder in a double planetary mixer at 135-150°C and a speed of 30-50 rpm for 60-120 minutes. Rheologically homogeneous feed with a powder loading of 60-64vol%;

The content of each component in the paraffin-based binder is: 15-30wt.% low-density polyethylene, 10-15wt.% polypropylene, 5-7wt.% stearic acid and the balance of paraffin;

2. Injection molding: direct injection molding on the injection molding machine, the injection temperature is 135-150°C, the injection pressure is 70-110MPa, and the complex shape blank is obtained;

3. Degreasing: Two-step degreasing process of solvent degreasing and thermal degreasing is adopted. First, dissolve and degrease in trichlorethylene for 6-12 hours; then perform thermal degreasing and pre-sintering in a high-purity argon atmosphere. The degreasing process is as follows: heating to 250°C at a heating rate of 2°C/min and holding for 2 hours, then heating to 420°C at a heating rate of 3°C/min and holding for 1 hour, and then heating to 500°C at a heating rate of 5°C/min and holding for 0.5 h, and finally pre-sintered at 650-750°C for 1-1.5h to obtain a degreased green body;

4. Sintering: The degreased body is sintered in a vacuum atmosphere with a vacuum degree of 1×10 ^-4 Pa, a sintering temperature of 1180-1240°C, and a holding time of 60-180 minutes to obtain a sintered body;

5. Uncovered hot isostatic pressing: the sintered billet is subjected to uncoated hot isostatic pressing within the temperature range of 1150-1200 ° C, the pressure is 100-200 MPa, and the holding time is 60-120 minutes to obtain full density (density greater than 99%) body;

6. Heat treatment: The solid-dense green body is subjected to solution treatment at 1150-1200°C, water-cooled after holding for 1-2 hours, and then subjected to aging treatment at 650-700°C to finally obtain a complex-shaped superalloy.

In the present invention, highly active alloying elements (such as Cr, Ti, Al, Ta, Nb, Zr, Hf, B, Re and C) are prepared into master alloys in advance, and then added in the form of master alloys instead of individual elements. In the material, it is not limited by conditions such as the easy oxidation of alloy elements, and can effectively avoid the oxidation of active elements, which is conducive to reducing the oxygen content and expanding the way of alloying. The master alloy is easy to break, and it is convenient to obtain fine alloy powder. The cost of raw material powder is low, which can reduce the sintering temperature, so that the sintering process can be carried out under the condition that there is no liquid phase or only a small amount of liquid phase appears, which helps to solve the problem of sintering deformation of the product, can improve the dimensional accuracy of the sample, and can also significantly Reduce raw material powder cost and process energy consumption. The prepared superalloy is close to fully dense, uniform in structure and excellent in comprehensive mechanical properties.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

Example 1: Near net shape preparation of iron-based superalloy K213

According to the composition of the iron-based superalloy K213 (35wt.%Ni, 15wt.%Cr, 1.8wt.%Al, 3.5wt.%Ti, 5wt.%W, 0.08wt.%B, 0.08wt.%C and the balance Fe) Design master alloy, the content of matrix element Fe in the master alloy is 25wt.%, and the rest are active elements, where W _Cr :W _Al :W _Ti :W _B :W _C ＝15:1.8:3.5:0.08:0.08） . The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. Next, the master alloy ingot is turned into chips, and the chips are broken into fine particles on a high-speed pulverizer. The fine particles were further refined by jet crushing, the gas pressure was 8 MPa, and the frequency of the sorting wheel was 60 Hz to obtain master alloy powder with an average particle size of 6.6 μm. In a high-purity Ar atmosphere (99.999%), fine-grained (2-10 μm) metal powders (such as carbonyl nickel powder, carbonyl iron powder, reduced tungsten powder) are subjected to high-energy ball milling with master alloy powder to obtain mixed powder. The composition of the paraffin-based binder is: 15wt.% low-density polyethylene, 15wt.% polypropylene, 6wt.% stearic acid and the rest paraffin. First, mix the mixed powder and paraffin-based binder in a double planetary mixer at 135°C and a speed of 30 rpm for 120 minutes to make a feed with uniform rheological properties, and the powder loading is 60vol.%. . The feed material is injection-molded on a CJ80-E injection molding machine with an injection temperature of 140°C and an injection pressure of 100MPa to obtain a complex-shaped green body. The complex-shaped green body was dissolved in trichlorethylene at 40°C for 10 hours, and then thermally degreased in a high-purity argon atmosphere. Heat at a heating rate of 1 min to 420°C for 1 hour, then heat at a rate of 5°C/min to 500°C and hold for 0.5 hours, and finally pre-sinter at 650°C for 1.5 hours to obtain a degreased green body. The degreased body was sintered in a vacuum atmosphere with a vacuum degree of 1×10 ^-4 Pa, a sintering temperature of 1180° C., and a holding time of 180 minutes to obtain a sintered body. The sintered compact was subjected to hot isostatic pressing without jacket at 1100°C, the pressure was 200MPa, and the holding time was 120min to obtain a fully dense compact. The full-dense body was solution treated at 1150°C for 2 hours, then water-cooled, and then aged at 650°C for 2 hours to obtain superalloy parts with complex shapes.

Embodiment 2: Nickel-base superalloy K418 is prepared near net shape

The master alloy is designed according to the composition of the nickel-based superalloy K418 (13%Cr, 6.0%Al, 0.8%Ti, 4.2%Mo, 2.3%Nb, 0.04%B, 0.09%Zr, 0.08%C and the balance of Ni). The content of matrix element Ni in the alloy is 30wt.%, and the rest are active elements. The mass ratio of each active element is: W _Cr :W _Al :W _Ti :W _Nb :W _B :W _Zr :W _C ＝13:6: 0.8:2.3:0.04:0.09:0.08). The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. Next, the master alloy ingot is turned into chips, and the chips are broken into fine particles on a high-speed pulverizer. The fine particles are further refined by jet crushing, the gas pressure is 6MPa, the frequency of the sorting wheel is 50Hz, and the master alloy powder with an average particle size of 7.2μm is obtained. In a high-purity Ar atmosphere (99.999%), fine-grained (2-10 μm) metal powders (such as carbonyl nickel powder, reduced molybdenum powder) and master alloy powders are subjected to high-energy ball milling to obtain mixed powders; paraffin-based binders The ingredients are: 20wt.% low-density polyethylene, 12wt.% polypropylene, 5wt.% stearic acid and the rest paraffin. First, the mixed powder and paraffin-based binder were mixed for 90 minutes in a double planetary mixer at 140°C and a speed of 35 rpm to make a feed with uniform rheological properties, and the powder loading was 62vol.%. . The feed material is injection-molded on a CJ80-E injection molding machine with an injection temperature of 135°C and an injection pressure of 110MPa to obtain a complex-shaped green body. The complex-shaped green body was dissolved in trichlorethylene at 40°C for 10 hours, and then thermally degreased in a high-purity argon atmosphere. Heat at a heating rate of 1 min to 420°C for 1 hour, then heat at a rate of 5°C/min to 500°C and hold for 0.5 hours, and finally pre-sinter at 700°C for 1.5 hours to obtain a degreased green body. The degreased body was sintered in a vacuum atmosphere with a vacuum degree of 1×10 ^-4 Pa, a sintering temperature of 1200° C., and a holding time of 180 minutes to obtain a sintered body. The sintered compact was subjected to hot isostatic pressing without jacket at 1100°C, the pressure was 200MPa, and the holding time was 120min to obtain a fully dense compact. The full-dense body was solution treated at 1180°C for 2 hours, then water-cooled, and then aged at 680°C for 2 hours to obtain superalloy parts with complex shapes.

Example 3: Near net shape preparation of nickel-based superalloy René104

According to the composition of nickel-based superalloy René104 (20%Co, 13%Cr, 3.8%Mo, 3.4%Al, 3.7%Ti, 2.1%W, 0.9Nb, 0.05%C, 0.025%B, 0.05%Zr, 2.4% Ta and balance Ni) to design a master alloy, the content of the matrix element Ni in the master alloy is 35wt.%, and the rest are active elements, and the mass ratio of each active element is: W _Cr : W _Al : W _Ti : W _Nb : W _C :W _B :W _Zr :W _Ta ＝13:3.4:3.7:0.9:0.05:0.025:0.05:2.4). The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. Next, the master alloy ingot is turned into chips, and the chips are broken into fine particles on a high-speed pulverizer. The fine particles were further refined by jet crushing, the gas pressure was 5 MPa, and the frequency of the sorting wheel was 40 Hz to obtain master alloy powder with an average particle size of 8.0 μm. In a high-purity Ar atmosphere (99.999%), fine-grained (2-10 μm) metal powders (such as ultra-fine cobalt powder, carbonyl nickel powder, reduced tungsten powder, reduced molybdenum powder) are subjected to high-energy ball milling with master alloy powder to obtain Mix powder. The composition of the paraffin-based binder is: 25wt.% low-density polyethylene, 10wt.% polypropylene, 7wt.% stearic acid and the rest paraffin. First, mix the mixed powder and paraffin-based binder in a double planetary mixer at 145°C and 40 rpm for 90 minutes to make a feed with uniform rheological properties, and the powder loading is 64vol.%. . The feed material is injection-molded on a CJ80-E injection molding machine with an injection temperature of 145°C and an injection pressure of 80MPa to obtain a green body with a complex shape. The complex-shaped green body was dissolved in trichlorethylene at 40°C for 10 hours, and then thermally degreased in a high-purity argon atmosphere. Heat at a heating rate of 420°C for 1 hour, then heat at a heating rate of 5°C/min to 500°C and hold for 0.5 hour, and finally pre-sinter at 750°C for 1 hour to obtain a degreased green body. The degreased body was sintered in a vacuum atmosphere with a vacuum degree of 1×10 ^-4 Pa, a sintering temperature of 1210° C., and a holding time of 180 minutes to obtain a sintered body. The sintered compact was subjected to hot isostatic pressing without jacket at 1100°C, the pressure was 200MPa, and the holding time was 120min to obtain a fully dense compact. The full-dense body was solution treated at 1200°C for 2 hours, then water-cooled, and then aged at 680°C for 2 hours to obtain superalloy parts with complex shapes.

Embodiment 4: Preparation of cobalt-based superalloy Mar-M509 near net shape

The master alloy is designed according to the composition of the cobalt-based superalloy Mar-M509 (10%Ni, 24%Cr, 7%W, 3.5%Ta, 0.2%Ti, 0.5%Zr, 0.6%C and the balance of cobalt). The content of the matrix element Co is 40wt.%, and the rest are active elements. The mass ratio of each active element is: W _Cr : W _Ta : W _Ti : W _Zr : W _C =24: 3.5:0.2:0.5:0.6). The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots. Next, the master alloy ingot is turned into chips, and the chips are broken into fine particles on a high-speed pulverizer. The fine particles are further refined by jet crushing, the gas pressure is 3MPa, the frequency of the sorting wheel is 40Hz, and the master alloy powder with an average particle size of 9.6μm is obtained. In a high-purity Ar atmosphere (99.999%), fine-grained (2-10 μm) metal powders (such as carbonyl nickel powder, reduced tungsten powder, ultra-fine cobalt powder) are subjected to high-energy ball milling with master alloy powder to obtain mixed powder; paraffin wax The composition of the base binder is: 30wt.% low-density polyethylene, 15wt.% polypropylene, 5wt.% stearic acid and the rest paraffin. First, mix the mixed powder and paraffin-based binder in a double planetary mixer at 150°C and a speed of 50 rpm for 60 minutes to make a feed with uniform rheological properties, and the powder loading is 63vol.%. . The feed material is injection-molded on a CJ80-E injection molding machine with an injection temperature of 150°C and an injection pressure of 70MPa to obtain a complex-shaped green body. The complex-shaped green body was dissolved in trichlorethylene at 40°C for 10 hours, and then thermally degreased in a high-purity argon atmosphere. Heat at a heating rate of 1 min to 420°C for 1 hour, then heat at a rate of 5°C/min to 500°C and hold for 0.5 hours, and finally pre-sinter at 700°C for 1.5 hours to obtain a degreased green body. The degreased body was sintered in a vacuum atmosphere with a vacuum degree of 1×10 ^-4 Pa, a sintering temperature of 1240° C., and a holding time of 180 minutes to obtain a sintered body. The sintered compact was subjected to hot isostatic pressing without jacket at 1100°C, the pressure was 200MPa, and the holding time was 120min to obtain a fully dense compact. The full-dense body was solution treated at 1180°C for 2 hours, then water-cooled, and then aged at 700°C for 2 hours to obtain superalloy parts with complex shapes.

Claims (2)

1. A method for preparing powder superalloys near net shape, characterized in that: Step 1. Design the master alloy according to the type and content of the alloy elements in the target superalloy. The content of the matrix elements in the master alloy is 25-40wt.%, and the rest are active elements, and the mass ratio of various active elements is the same as that in the target superalloy. The mass ratio of each element is consistent; The master alloy is smelted in a vacuum induction melting furnace to obtain master alloy ingots; Next, the master alloy ingot is turned into chips, and the chips are broken into fine particles on a high-speed pulverizer; The fine particles are further refined by jet crushing to obtain master alloy powder, the gas pressure is 3~8MPa, and the frequency of the sorting wheel is 40~60Hz; On a high-energy ball mill, in a 99.999% high-purity Ar atmosphere, the master alloy powder is mixed with 2-10μm fine-grained metal powder to obtain a mixed powder; the matrix elements are Fe, Ni or Co, and the active elements are Cr, Ti, Al, Ta, Nb, Zr, Hf, B, Re and C, metal powders are carbonyl nickel powder, carbonyl iron powder, ultrafine cobalt powder, reduced tungsten powder, reduced molybdenum powder; Step 2. Mix the mixed powder with a particle size of less than 20 μm and a paraffin-based binder in a double planetary mixer at 135-150°C and a speed of 30-50 rpm for 60-120 minutes to make rheology Uniform feeding with powder loading of 60-64vol%; Step 3, direct injection molding on an injection molding machine, the injection temperature is 135-150°C, and the injection pressure is 70-110MPa, to obtain a complex shape green body; Step 4: Use solvent degreasing and thermal degreasing two-step degreasing process, first dissolve in trichlorethylene for 6-12h; then perform thermal degreasing and pre-sintering in a high-purity argon atmosphere; the degreasing process is: at 2°C/min Heating rate to 250°C for 2 hours, then heating to 420°C for 1 hour at a rate of 3°C/min, heating to 500°C for 0.5 hour at a rate of 5°C/min, and pre-sintering at 650-750°C 1-1.5h, get the degreased body; Step 5, the degreased green body is sintered in a vacuum atmosphere, the vacuum degree is 1×10 ^-4 Pa, the sintering temperature is 1180-1240°C, and the holding time is 60-180min, to obtain a sintered green body; Step 6. The sintered compact is subjected to hot isostatic pressing without jacket in the temperature range of 1150-1200° C., the pressure is 100-200 MPa, and the holding time is 60-120 minutes to obtain a fully dense green body with a density greater than 99%. Step 7: The full-dense green body is subjected to solution treatment at 1150-1200°C, heat-preserved for 1-2 hours, then water-cooled, and then subjected to aging treatment at 650-700°C to finally obtain a complex-shaped superalloy. 2. according to the method for preparing powder superalloy of near-net shape described in claim 1, it is characterized in that: described target superalloy is the iron-based superalloy of various standard grades, nickel-based superalloy, cobalt-based superalloy, or It is a non-standard alloy designed according to actual working conditions; iron-based superalloys are K213, GH2036, GH2038 or GH2132, nickel-based superalloys such as K418, René104, GH4049 or GH4169, cobalt-based superalloys are Mar-M509, FSX-414 , Mar-M302 or Haynes25; The method for preparing a powder superalloy in a near-net shape according to claim 1, characterized in that: the average particle size of the master alloy powder is ≤10 μm; The method for preparing a powder superalloy in a near-net shape according to claim 1, characterized in that: the content of each component in the paraffin-based binder is: 15-30wt.% low-density polyethylene, 10-15wt. % polypropylene, 5-7wt.% stearic acid and the balance paraffin.