A method for predicting solution treatment porosity in a nickel-based powder superalloy

Abstract

The application discloses a method for predicting porosity of nickel-based powder high-temperature alloy after solid solution treatment, and belongs to the technical field of metal material testing. First, the initial porosity of the nickel-based powder high-temperature alloy is determined, and then the initial porosity and solid solution treatment parameters are input into a porosity prediction model, so that the porosity of the nickel-based powder high-temperature alloy after the solid solution treatment can be obtained. The application can predict the porosity of the nickel-based powder high-temperature alloy after the solid solution treatment, so as to provide a reference for selection of a solid solution treatment process of the nickel-based powder high-temperature alloy, reduce the trial and error cost of the solid solution treatment, and improve the product quality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal material testing, and particularly relates to a method for predicting porosity of nickel-based powder high-temperature alloy solid solution treatment. BACKGROUND

[0002] High-temperature alloys are widely used in aerospace, nuclear engineering, energy power, chemical industry and other high-temperature environments with corrosion resistance and oxidation resistance due to their excellent performance. With the development of modern aerospace technology, the thrust-to-weight ratio and thrust-to-weight force of engines are continuously improved, and the working temperature and performance requirements of high-temperature alloys are also higher and higher. In order to meet the new requirements, the alloying degree is also higher and higher, so that the alloy performance is deteriorated, which is not conducive to casting and deformation processing. With the rise of gas atomization powder preparation technology, people prepare powder high-temperature alloy turbine discs, and the performance is greatly improved, so the powder high-temperature alloy is rapidly developed. The powder high-temperature alloy component preparation process is as shown in the figure. Figure 1

[0003] Compared with the traditional casting / forging nickel-based high-temperature alloy, the advantages of the nickel-based powder high-temperature alloy include the following aspects. First, the alloy liquid droplets are rapidly solidified to form powder particles in the atomization powder preparation process, and the composition segregation is limited within the micron-level powder particles, so that the macro-segregation in conventional casting is eliminated. Second, the powder after rapid solidification has the characteristics of uniform organization and small grain size, and the mechanical properties and hot working properties of the alloy are significantly improved. Therefore, the nickel-based powder high-temperature alloy is widely used in the manufacture of engine turbine discs, compressor discs, turbine baffles and other hot end components, and is an important symbol of advanced aero-engines. However, due to the particularity of the manufacturing process, some defects are inevitably introduced, mainly including prior particle boundary (PPB), thermal induced porosity (TIP) and inclusions, which seriously affect the mechanical properties and use reliability of the powder high-temperature alloy.

[0004] As one of the main defects of the powder high-temperature alloy, the thermal induced porosity TIP refers to that in the hot isostatic pressing process, the inert gas (Ar) involved does not react with the alloy elements, and cannot be discharged from the package, and is left in the alloy blank, and under the action of high pressure, closed pores containing inert gas are formed, and in the subsequent solid solution treatment process, the residual inert gas expands under the heat to form discontinuous pores in the alloy, and the sources mainly include the following aspects: (1) In the powder preparation or powder treatment process, the argon gas adsorbed on the surface of the powder is not completely removed; (2) The argon gas and other inert gases are involved in the powder, or the argon gas is contained in the hollow powder; (3) The package is not tightly sealed, and the high-pressure inert gas is infiltrated in the hot isostatic pressing process.

[0005] ​During the solution treatment of heat treatment, the pressure of inert gas increases with the increase of time and temperature, the deformation resistance of metal decreases, the diffusion creep of the superalloy is promoted, the TIP grows rapidly, the volume fraction of TIP increases, and the mechanical properties such as tensile, endurance and creep of the alloy are deteriorated. In addition, the formation of TIP not only causes the workpiece to warp, but also easily causes stress concentration around TIP, forms a crack source, causes the alloy to crack during heat treatment, and further affects the use reliability and safety of the alloy.

[0006] In order to ensure the use reliability and safety of the alloy, it is necessary to understand the change of TIP before and after the solution treatment. SUMMARY

[0007] In view of the above problems, the present application provides a method for predicting the porosity of nickel-based powder superalloy during solution treatment, which establishes a model for predicting the porosity of nickel-based powder superalloy during solution treatment according to the main factors affecting the growth of TIP during solution treatment.

[0008] The technical scheme of the present application is as follows:

[0009] A method for predicting the porosity of nickel-based powder superalloy during solution treatment, specifically comprising the following steps:

[0010] (1) embedding, polishing, mechanical polishing, cleaning and drying treatment are performed on the nickel-based powder superalloy sample;

[0011] (2) observing the pretreated nickel-based powder superalloy sample under an optical microscope, randomly taking several metallographic photos, statistically analyzing the randomly taken metallographic photos according to the national standard GB / T 15749-2008 quantitative metallographic determination method, and calculating the initial porosity P0;

[0012] (3) inputting the initial porosity P0 calculated in step (2) and the solution treatment parameters into the porosity prediction model to obtain the porosity P of the nickel-based powder superalloy after solution treatment:

[0013]

[0014] Wherein, P is the porosity after solution treatment, %; P0 is the initial porosity, %; t is the time in the solution treatment parameters, h; T is the temperature in the solution treatment parameters, K; Q is the pore growth activation energy, kJ / mol; R is the gas constant 8.314 J / (mol·K); A, n are material constants, Q takes the value range of: 1.8×10 5 ~ 2.5×10 5 , A takes the value range of: 1.0×10 10 ~ 8.2×10 10 , n takes the value range of: 1.4~2.0.

[0015] The chemical composition and mass percentage content of the nickel-based powder superalloy are as follows: Cr: 8.0-10.0%, Co: 15.0-16.5%, W: 4.8-5.9%, Mo: 3.5-4.2%, Al: 4.85-5.25%, Ti: 1.6-2.0%, Nb: 2.4-2.8%, Hf: 0.1-0.4%, and Ni: the balance.

[0016] In the mechanical polishing of the sample in step (1), first, the diamond polishing paste with a particle size of 3.5 μm is used for rough polishing, and when the polishing trace direction is consistent, the diamond polishing paste with a particle size of 1.5 μm is used for fine polishing until the sample surface has no obvious scratches under optical microscope observation.

[0017] In step (2), the initial porosity P0 is the average value or the worst value of the statistical results.

[0018] In step (3), the solution treatment parameters include solution treatment time and temperature.

[0019] The beneficial technical effects of the present application are as follows: the present application can predict the change of the porosity of the nickel-based powder superalloy after solution treatment, can provide a reference for optimizing the solution treatment process of the nickel-based powder superalloy, can reduce the trial and error cost of the solution treatment process, and can improve the production efficiency and product quality. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The powder metallurgy product manufacturing process is shown in the following table:

[0021] Figure 2 The metallographic diagram of the TIP (average value) of the nickel-based powder superalloy after solution treatment of Example 1 changing with the solution time is shown in the following figure:

[0022] Figure 3 The metallographic diagram of the TIP (average value) of the nickel-based powder superalloy after solution treatment of Example 2 changing with the solution temperature is shown in the following figure:

[0023] Figure 4 The metallographic diagram of the TIP (worst value) of the nickel-based powder superalloy after solution treatment of Example 3 changing with the solution time is shown in the following figure:

[0024] Figure 5 The comparison results of the predicted value and the measured value of the porosity prediction model of the nickel-based powder superalloy after solution treatment are shown in the following table: DETAILED DESCRIPTION

[0025] The specific embodiments of the present application will be further described in detail below with reference to specific examples, but the protection scope of the present application is not limited to the content described.

[0026] Example 1

[0027] A method for predicting the porosity of a nickel-based powder superalloy after solution treatment, comprising the following steps:

[0028] Step 1: The original nickel-based powder superalloy sample (the composition and mass percentage of the nickel-based powder superalloy are as follows: Cr: 8.92%, Co: 16.11%, W: 5.57%, Mo: 3.81%, Al: 5.19%, Ti: 1.85%, Nb: 2.49%, Hf: 0.19%, and Ni: the balance) is subjected to inlaying, grinding, mechanical polishing, and water cleaning, and then is dried by a hair dryer; when the sample is mechanically polished, first use diamond polishing paste with a particle size of 3.5 μm for rough polishing, and then use diamond polishing paste with a particle size of 1.5 μm for fine polishing until the sample surface has no scratches under optical microscopy;

[0029] Step 2: Observe the pretreated nickel-based powder superalloy sample under an optical microscope, and randomly take several metallographic photos; according to the national standard GB / T 15749-2008 quantitative metallographic determination method, statistically analyze the randomly taken metallographic photos, and calculate the initial porosity (average value) P0 of the nickel-based powder superalloy as 0.108;

[0030] Step 3: Input the initial porosity of the nickel-based powder superalloy sample and the solution treatment parameters (time and temperature) into the porosity prediction model:

[0031]

[0032] wherein P is the porosity after solution treatment (%), P0 is the initial porosity (%), t is the solution treatment time (h), T is the solution treatment temperature (K), Q is the pore growth activation energy (kJ / mol), R is the gas constant (8.314 J / (mol·K)), A and n are material constants, Q is 2.3×10 5 , A is 4.47×10 10 , and n is 1.48;

[0033] The porosity P of the nickel-based powder superalloy after solution treatment at 1175℃ and different solution treatment times (2h, 4h, 8h) can be obtained; the alloy is actually subjected to solution treatment, and according to the national standard GB / T 15749-2008 quantitative metallographic determination method, the randomly taken metallographic photos are statistically analyzed, and the TIP average value of the nickel-based powder superalloy after different solution treatment times is calculated, as shown in Figure 2 ​The TIP measured average value of the alloy after solution treatment, P is the TIP predicted value (average value) after solution treatment, from the results, the difference between the TIP predicted value and the measured value is small, and the prediction model has high prediction accuracy.

[0034] Example 2

[0035] A method for predicting the porosity of a nickel-based powder superalloy after solution treatment, the specific steps are as follows:

[0036] Step one, the original state of the nickel-based powder superalloy sample (nickel-based powder superalloy composition and its mass percentage: Cr: 8.92%, Co: 16.11%, W: 5.57%, Mo: 3.81%, Al: 5.19%, Ti: 1.85%, Nb: 2.49%, Hf: 0.19%, Ni: balance) is embedded, polished, mechanically polished, washed with clean water, and dried with a hair dryer; when the sample is mechanically polished, first use diamond polishing paste with a particle size of 3.5 μm for rough polishing, and when the polishing trace direction is consistent, use diamond polishing paste with a particle size of 1.5 μm for fine polishing, until the sample surface is free of scratches under optical microscope observation;

[0037] Step two, observe the pretreated nickel-based powder superalloy sample under an optical microscope and randomly take several metallographic photos, statistically analyze the randomly taken metallographic photos according to the national standard GB / T 15749-2008 quantitative metallographic determination method, and calculate the initial porosity (average value) P0 of the nickel-based powder superalloy as 0.026;

[0038] Step three, input the initial porosity of the nickel-based powder superalloy sample and the solution treatment parameters (time, temperature) into the porosity prediction model:

[0039]

[0040] Wherein, P is the porosity (%) after solution treatment, P0 is the initial porosity (%), t is the solution treatment time (h), T is the solution treatment temperature (K), Q is the pore growth activation energy (kJ / mol), R is the gas constant (8.314 J / (mol·K)), A, n are material constants, wherein Q is 2.0×10 5 , A is 1.0×10 10 , and n is 1.45;

[0041] The porosity P of the nickel-based powder superalloy after different treatment temperatures (1150°C, 1175°C, 1200°C) and the same solution treatment time (0.5h) can be obtained. The alloy is subjected to actual solution treatment, and the randomly taken metallographic pictures are statistically analyzed according to the national standard GB / T15749-2008 quantitative metallographic determination method to calculate the measured average value of TIP of the nickel-based powder superalloy after different solution treatment temperatures, as shown in FIG. Figure 3 As shown, represents the measured average value of TIP of the alloy after solution treatment, and P is the predicted value (average value) of TIP after solution treatment. From the results, it can be seen that the prediction model has high accuracy, and the higher the temperature, the higher the accuracy of the model.

[0042] Example 3

[0043] A method for predicting porosity of nickel-based powder high-temperature alloy solution treated, the specific steps are as follows:

[0044] Step 1: The original nickel-based powder high-temperature alloy sample (the composition and mass percentage of the nickel-based powder high-temperature alloy are: Cr: 8.92%, Co: 16.11%, W: 5.57%, Mo: 3.81%, Al: 5.19%, Ti: 1.85%, Nb: 2.49%, Hf: 0.19%, Ni: balance) is inlaid, ground, mechanically polished, cleaned with water, and dried with a hair dryer; when the sample is mechanically polished, a diamond polishing paste with a particle size of 3.5 μm is first used for rough polishing. When the polishing marks are in the same direction, a diamond polishing paste with a particle size of 1.5 μm is used for fine polishing until the sample surface is free of scratches when observed under an optical microscope;

[0045] Step 2: Observe the pretreated nickel-based powder superalloy sample under an optical microscope and randomly take several metallographic photographs. The randomly taken metallographic photographs are statistically analyzed according to the national standard GB / T 15749-2008 quantitative metallographic determination method, and the initial porosity (worst value) P0 of the nickel-based powder superalloy is calculated to be 0.116;

[0046] Step 3: Input the initial porosity and solution treatment parameters (time, temperature) of the nickel-based powder high-temperature alloy sample into the porosity prediction model:

[0047]

[0048] Where P is the porosity after solution treatment (%), P0 is the initial porosity (%), t is the solution treatment time (h), T is the solution treatment temperature (K), Q is the pore growth activation energy (kJ / mol), R is the gas constant (8.314 J / (mol·K)), A and n are material constants, and the Q value is 2.31×105 A value is 4.33 x 10 10 n is 1.43;

[0049] The porosity P of the nickel-based powder superalloy after different solution treatment time (2h, 4h, 8h) at 1200℃ can be obtained, the alloy is actually solution treated, and the worst value of TIP of the nickel-based powder superalloy after different solution treatment time is calculated according to the quantitative metallographic determination method of national standard GB / T 15749-2008, the metallographic picture is randomly taken and counted, as shown in Figure 4 The worst value of TIP of the alloy after solution treatment is represented, and P is the predicted value (worst value) of TIP after solution treatment. From the results, the accuracy of the prediction model is high.

[0050] Figure 5 The comparison results of the predicted value and the measured value of the porosity prediction model for example 1 (P0 is the average value of TIP) and example 3 (P0 is the worst value of TIP) are shown in the figure. From the figure, it can be seen that the model has good prediction accuracy for the change of TIP during the solution treatment process.​

Claims

1. A method for predicting the porosity of nickel-based powder high-temperature alloy after solution treatment, characterized in that: The specific steps include: (1) Mounting, grinding, mechanical polishing, cleaning and drying the nickel-based powder high-temperature alloy sample; (2) Observe the pretreated nickel-based powder high-temperature alloy sample under an optical microscope and randomly take several metallographic photographs. The randomly taken metallographic photographs are statistically analyzed according to the national standard GB / T 15749-2008 quantitative metallographic determination method, and the initial porosity P0 is calculated; (3) The initial porosity P0 and the solution treatment parameters calculated in step (2) are input into the porosity prediction model to obtain the porosity P of the nickel-based powder high-temperature alloy after solution treatment: Where P is the porosity after solution treatment, %; P0 is the initial porosity, %; t is the time in the solution treatment parameters, h; T is the temperature in the solution treatment parameters, K; Q is the pore growth activation energy, kJ / mol; R is the gas constant 8.314 J / (mol·K); A, n are material constants, Q = 1.8×10 5 ~2.5×10 5 , A=1.0×10 10 ~8.2×10 10 , n=1.4~2.

0.

2. The method for predicting the porosity of a nickel-based powder superalloy after solution treatment according to claim 1, characterized in that: The chemical composition and mass percentage content of the nickel-based powder high-temperature alloy are: Cr: 8.0-10.0%, Co: 15.0-16.5%, W: 4.8-5.9%, Mo: 3.5-4.2%, Al: 4.85-5.25%, Ti: 1.6-2.0%, Nb: 2.4-2.8%, Hf: 0.1-0.4%, and Ni: balance.

3. The method for predicting the porosity of a nickel-based powder superalloy after solution treatment according to claim 1, characterized in that: When the sample is mechanically polished in step (1), a diamond polishing paste with a particle size of 3.5 μm is first used for rough polishing. When the polishing marks are in the same direction, a diamond polishing paste with a particle size of 1.5 μm is used for fine polishing until the sample surface is free of scratches when observed under an optical microscope.

4. The method for predicting the porosity of a nickel-based powder superalloy after solution treatment according to claim 1, characterized in that: The initial porosity P0 in step (2) is the average value or the worst value of the statistical results.

5. The method for predicting the porosity of nickel-based powder high-temperature alloy after solution treatment according to claim 1, characterized in that: The solution treatment parameters in step (3) include solution treatment time and temperature.

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