Superalloy powder, components, and a method for manufacturing components from the powder.

Abstract

A nickel-based superalloy powder containing, by mass percentage, 14.00-15.25% chromium, 14.25-15.75% cobalt, 3.9-4.5% molybdenum, 4.0-4.6% aluminum, 3.0-3.7% titanium, 0-200 ppm carbon, and the remainder consisting of nickel and unavoidable impurities. Components made from the powder and methods for manufacturing the components (100).

Description

Technical Field

[0001] The present disclosure relates to superalloy powders, components made from such powders, and methods for manufacturing such components from such powders.

Background Art

[0002] Methods for manufacturing metallic components by powder injection, called metal injection molding (MIM), include the step of mixing metal powder with a plastic binder so that the mixture can be injected into a mold. The as-formed component obtained in the injection mold is then debound and sintered to provide a high density component. When the alloy is a nickel-based superalloy, the high density component is then heat treated to obtain the desired properties.

[0003] However, in the MIM manufacturing method of Rene77 alloy, it is difficult to obtain components having excellent creep behavior, especially at temperatures above 800 degrees Celsius (°C).

[0004] This high temperature creep behavior can have a negative impact on Rene77 components produced by MIM. This creep behavior can limit the fields of use of Rene77 components manufactured by the MIM method.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure aims to at least partially correct these demerits.

Means for Solving the Problems

[0006] For this purpose, the present disclosure relates to a nickel-based superalloy powder containing 14.00 to 15.25% chromium, 14.25 to 15.75% cobalt, 3.9 to 4.5% molybdenum, 4.0 to 4.6% aluminum, 3.0 to 3.7% titanium, 0 to 0.10 copper, 0 to 0.50 iron, 0 to 200 ppm carbon by mass percentage, with the balance being composed of nickel and inevitable impurities.

[0007] This powder is intended for the manufacture of nickel-based superalloy components, such as blades or vanes, such as gas turbine blades.

[0008] The main additive elements are cobalt (Co), chromium (Cr), molybdenum (Mo), aluminum (Al) and titanium (Ti).

[0009] The minor additive elements are copper (Cu) and iron (Fe), and their maximum mass percentage is less than 1%.

[0010] Inevitable impurities are defined as elements that are not intentionally added to the composition but are brought in with other elements. Examples of inevitable impurities include silicon (Si), manganese (Mn), oxygen (O), sulfur (S), boron (B) and yttrium (Y).

[0011] Although an upper limit can be provided for the carbon content of nickel-based superalloys, it is pointed out that nickel-based superalloys generally have a carbon content close to this upper limit. Therefore, a superalloy containing less than 500 ppm carbon is understood to have a carbon content close to 500 ppm, and the carbon content is generally more than 300 ppm.

[0012] The carbon content of the as-received components and the binder-removed components can be limited by the carbon content of the powder being 200 ppm (ppm by mass) or less. Since the carbon content of the debound components decreases during the sintering step, precipitation of carbides at the grain boundaries can be significantly reduced compared to conventional powders having a similar composition with a carbon content generally exceeding 500 ppm, and further exceeding 700 ppm.

[0013] In fact, the inventors have identified that one of the causes limiting the creep properties of the components is the presence of carbides at the grain boundaries that slow down or even prevent the growth of the grains in the sintered components.

[0014] Thus, during the heat treatment step for growing grains in the sintered components, it is possible to obtain grains having a larger size than that obtainable with conventional powders with a carbon content generally exceeding 500 ppm, and further exceeding 700 ppm.

[0015] Since the grain size is larger compared to that obtainable with conventional powders with a carbon content generally exceeding 500 ppm, and further exceeding 700 ppm, the creep behavior of the components is improved.

[0016] In some embodiments, the superalloy powder contains 5 - 200 ppm of carbon.

[0017] In some embodiments, the superalloy powder has a D90 particle size of 75 μm or less, preferably 50 μm or less, when measured by laser diffraction according to the ISO 13320 standard.

[0018] The smaller the particle size of the powder, the lower the sintering temperature and the higher the density of the sintered components.

[0019] In some embodiments, the superalloy powder has a spherical morphology.

[0020] The spherical morphology is advantageous for the MIM process and sintering.

[0021] The present disclosure also relates to components made from nickel-based superalloy powders as defined above, containing less than 700 ppm carbon, preferably less than 600 ppm carbon.

[0022] In some embodiments, the component is obtained by a powder injection molding process.

[0023] In some embodiments, the average grain size is ASTM 6 or more, preferably ASTM 5 or more, more preferably ASTM 4 or more when measured according to the ASTM E112-13 standard.

[0024] The present disclosure also relates to a method for manufacturing a component from a nickel-based superalloy powder as defined above, - mixing at least two binders with the nickel-based superalloy powder to obtain a mixture; - injection molding the mixture in a mold to obtain a raw component; - debinding the raw component to obtain a binder-removed component; - sintering the binder-removed component to obtain a sintered component; - heat-treating the sintered component, including growing the crystal grains and precipitating the γ' phase such that the size of the average crystal grains is ASTM 6 or more, preferably ASTM 5 or more, and even more preferably ASTM 4 or more when measured according to ASTM E112-13; and relates to a manufacturing method including the above steps.

[0025] In some embodiments, the sintering step is performed in a temperature step of 1 hour to 6 hours.

[0026] In some embodiments, the grain growth step is carried out at a temperature step for 1 hour or more and 20 hours or less, preferably 15 hours or less, and even more preferably 10 hours or less.

[0027] In some embodiments, the step of precipitating the γ' phase is carried out at a temperature step for 1 hour or more and 20 hours or less, preferably 15 hours or less, and more preferably 10 hours or less.

[0028] In some embodiments, the input rate of the mixture is 55% or more, preferably 60% or more, and 75% or less, preferably 70% or less.

[0029] The input rate of the mixture is defined as the ratio of the powder to the total volume (powder + additive). The additive includes a binder and may include other additives.

[0030] In some embodiments, the debinding treatment step is carried out in two sub-steps: a first sub-step of debinding the primary binder and a second sub-step of debinding the secondary binder.

[0031] The second debinding treatment sub-step is a thermal step, that is, a step of heating the component to obtain a component from which the secondary binder has been burned off and the binder removed.

[0032] Other features and advantages of the present disclosure will become apparent from the following description of the embodiments shown as non-limiting examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

DETAILED DESCRIPTION OF THE INVENTION

[0034] Figure 1 schematically shows a method 100 for manufacturing a component from a nickel-based superalloy powder containing 0 to 200 ppm of carbon, preferably 5 to 200 ppm of carbon.

EXAMPLES

[0035] Two types of superalloy powder compositions were studied: a composition containing 160 ppm of carbon (Example 1) and a composition similar to that of Example 1 but containing 740 ppm of carbon (Example 2).

[0036] Table 1 shows the respective compositions of Examples 1 and 2 (Ex1 and Ex2) in mass percentages, with the remainder consisting of nickel and unavoidable impurities.

[0037] Example 1 further contains 0.060 mass% of silicon and 0.030 mass% of oxygen as unavoidable impurities.

[0038] Example 2 further contains 0.050 mass% of silicon, 0.022 mass% of oxygen, and 0.014 mass% of manganese as unavoidable impurities.

[0039]

TABLE 1

[0040] During the mixing step 102, at least two binders, namely a thermoplastic primary binder that imparts rheological properties to the mixture to enable injection of the mixture into the mold, and a secondary binder that imparts mechanical strength to the green component to enable handling of the green component after demolding, are mixed with the superalloy powder.

[0041] Typically, the powder feed rate of the mixture, i.e., the volume of the powder in relation to the total volume (powder + additives), is 60 - 70%. The additives include binders and other additives.

[0042] In the described embodiment, the ratio of the primary binder to the secondary binder is 2:1 by mass, i.e., the mixture contains twice the amount of the primary binder as the secondary binder by mass.

[0043] Non-limiting examples of the thermoplastic primary binder can include paraffin, carnauba wax, beeswax, peanut oil, acetanilide, antipyrine, naphthalene, polyoxymethylene resin (POM).

[0044] Non-limiting examples of the secondary binder can include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyamide (PA), polyethylene vinyl acetate (PE-VA), polyethylene acrylate (PEA), polyphthalamide (PPA).

[0045] Non-limiting examples of other additives can include stearic acid, oleic acid and its esters, and phthalic acid esters.

[0046] Next, the step 104 of injection molding the mixture in the mold to obtain the green component is performed by a known method.

[0047] The debinding process step 106 is generally performed in two sub-steps. In the first sub-step 106A, the primary binder is subjected to a debinding process. This step of debinding the primary binder 106A is generally carried out at a temperature of 30°C to 100°C using a solvent. The solvent may be, for example, water.

[0048] The secondary binder is always present and imparts mechanical strength to the components to enable handling of the components.

[0049] The second debinding process sub-step 106B is a thermal step, that is, a step of heating the components to burn off the secondary binder and obtain the components from which the binder has been removed.

[0050] This second sub-step 106B is performed, for example, during the temperature rise for sintering the components. For example, the thermal debinding process step 106B is carried out at 400°C to 700°C with one stage being 30 minutes to 10 hours.

[0051] In the sintering step 108, the components from which the binder has been removed are densified. For example, the components are sintered at 1230°C to 1300°C for 5 hours.

[0052] Figures 2 and 3 show the microstructures of Example 2 and Example 1, respectively. After the sintering step 108 and before the heat treatment step 110, it can be seen that the average grain size is about ASTM 4 for Example 1 and about ASTM 8 for Example 2 when measured according to the ASTM E112-13 standard.

[0053] Next, the sintered components are heat-treated. The heat treatment step 110 includes a step 110A of growing the crystal grains such that the average crystal grain size measured according to ASTM E112-13 is ASTM 6 or more, preferably ASTM 5 or more, and more preferably ASTM 4 or more, and a step 110B of precipitating the γ' phase.

[0054] Typically, for Example 2, after the grain growth step 110A, the average grain size is about ASTM 6 for the grain growth step 110A performed at 1275 °C for 10 hours.

[0055] After the grain growth step 110A, for Example 1, the average grain size is about ASTM 3 for the grain growth step 110A performed at 1275 °C for 5 hours.

[0056] After the grain growth step 110A, the heat treatment step 110 includes a step 110B of precipitating the γ' phase. This step 110B of precipitating the γ' phase does not change the average grain size.

[0057] Between the sintering step 108 and the heat treatment step 110, the component can be cooled down to room temperature.

[0058] Between the grain growth step 110A and the precipitation step 110B, the component may be cooled down to room temperature.

[0059] The components obtained from the superalloy powder of Example 1 have better high-temperature creep behavior than the components obtained from the superalloy powder of Example 2. For reference, at 950 °C, assuming all test conditions are constant, a service life 2 to 2.5 times longer is observed for the components obtained from the superalloy powder of Example 1 than for the components obtained from the superalloy powder of Example 2. The test was a uniaxial tensile creep test carried out until failure according to the NF EN ISO204 standard.

[0060] Although the present disclosure has been described in connection with specific exemplary embodiments, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention defined by the claims. Furthermore, it is possible to combine the individual features of the various described embodiments in the form of additional embodiments. Therefore, the specification and drawings should be considered in an illustrative rather than a limiting sense. Some embodiments of the present invention are described in the following items [1] -

[10] . [1] A nickel-based superalloy powder containing 14.00 - 15.25% chromium, 14.25 - 15.75% cobalt, 3.9 - 4.5% molybdenum, 4.0 - 4.6% aluminum, 3.0 - 3.7% titanium, 0 - 0.10 copper, 0 - 0.50 iron, 0 - 200 ppm carbon by mass percentage, with the balance being nickel and unavoidable impurities. [2] The nickel-based superalloy powder according to claim 1, containing 5 - 200 ppm carbon. [3] The nickel-based superalloy powder according to item 1 or 2, having a D90 particle size of 75 μm or less, preferably 50 μm or less, when measured by laser diffraction according to the ISO13320 standard. [4] The nickel-based superalloy powder according to any one of items 1 - 3, having a spherical morphology. [5] A component made from the nickel-based superalloy powder according to any one of items 1 - 4, containing less than 700 ppm carbon, preferably less than 600 ppm carbon. [6] The component according to item 5, obtained by a powder injection molding process. [7] The component according to item 5 or 6, having an average grain size of ASTM 6 or more, preferably ASTM 5 or more, more preferably ASTM 4 or more, when measured according to the ASTM E112 - 13 standard. [8] A method (100) for manufacturing a component from the nickel-based superalloy powder according to any one of items 1 - 4, comprising: - Mixing at least two binders with the nickel-based superalloy powder to obtain a mixture step (102); - Injecting the mixture into a mold to obtain a raw component in step (104); - Debinding the raw component to obtain a binder-removed component in step (106); - Sintering the binder-removed component to obtain a sintered component in step (108 ); - Heat-treating the sintered component in step (110), growing the grains such that the average size of the grains is ASTM 6 or more, preferably A STM 5 or more, even more preferably ASTM 4 or more, when measured according to ASTM E112 - 1 3 in step (110A) and precipitating the γ' phase in step (110B) in step (110); - including step (110). A manufacturing method (100) including the above steps. [9] The manufacturing method (100) according to item 8, wherein the sintering step (108) is carried out in a temperature step of 1 hour to 6 hours.

[10] The manufacturing method (100) according to item 8 or 9, wherein the crystal grain growth step (110A) is carried out in a temperature step of 1 hour or more and 20 hours or less, preferably 15 hours or less, and even more preferably 10 hours or less.

Claims

1. A method (100) for manufacturing a component from a nickel-based superalloy powder, comprising 14.00 to 15.25% chromium, 14.25 to 15.75% cobalt, 3.9 to 4.5% molybdenum, 4.0 to 4.6% aluminum, 3.0 to 3.7% titanium, 0 to 0.10% copper, 0 to 0.50% iron, 0 to 200 ppm carbon by mass percentage, with the balance being composed of nickel and unavoidable impurities, comprising: - mixing at least two binders including a primary binder and a secondary binder with the nickel-based superalloy powder to obtain a mixture (step 102); - injection molding the mixture in a mold to obtain a raw component (step 104); - debinding the raw component to obtain a binder-removed component (step 106), wherein the debinding step is performed in two sub-steps: a first sub-step of debinding the primary binder and a second sub-step of debinding the secondary binder; - sintering the binder-removed component to obtain a sintered component (step 108); - heat-treating the sintered component (step 110), the heat-treating step (110) including a step (110A) of growing crystal grains such that an average size of crystal grains measured according to ASTM E112-13 is ASTM 6 or more and a step (110B) of precipitating a γ' phase; The manufacturing method (100) comprising the above steps.

2. The manufacturing method (100) according to claim 1, wherein the step (108) is performed in a temperature step of 1 hour to 6 hours.

3. The manufacturing method (100) according to claim 1 or 2, wherein the step (110A) is performed in a temperature step of 1 hour or more and 20 hours or less.

4. The manufacturing method (100) according to any one of claims 1 to 3, wherein the nickel-based superalloy powder contains 5 to 200 ppm carbon.

5. The manufacturing method (100) according to any one of claims 1 to 4, wherein the nickel-based superalloy powder has a D90 particle size of 75 μm or less when measured by laser diffraction according to ISO 13320 standard.

6. The manufacturing method (100) according to any one of claims 1 to 5, wherein the nickel-based superalloy powder has a spherical morphology.

7. The manufacturing method (100) according to any one of claims 1 to 6, wherein a second sub-step of performing a debinding process on the secondary binder is performed by obtaining a component from which the secondary binder has been removed by burning off the binder.

8. The manufacturing method (100) according to any one of claims 1 to 7, wherein the charging rate of the mixture is 55% or more.

Images