Preparation method of gradient quality control sample for nitrogen element analysis of nickel-based superalloy

Abstract

The invention discloses a preparation method of a gradient quality control sample for nitrogen element analysis of a nickel-based superalloy, belonging to the technical fields of material preparation and element analysis. By preparing an ingot with a gradient nitrogen element content, through homogenization treatment, two upsetting and drawing deformation treatments, surface turning, uniformity inspection and value determination analysis, a gradient quality control sample for nitrogen element analysis of a nickel-based superalloy is obtained, solving the problem that it is difficult to introduce nitrogen element in a gradient manner in the field of nickel-based superalloy material preparation. It provides a set of matrix-matched superalloy-like gradient quality control samples for the determination of nitrogen element by the inert gas fusion thermal conductivity method (relative method), improves the quality determination system of nitrogen element in superalloys, ensures the accuracy and traceability of nitrogen element determination in superalloy-like samples, and at the same time, the invention fills the blank of gradient quality control samples for nitrogen element in nickel-based superalloy samples.

Description

Technical Field

[0001] The present invention belongs to the technical fields of material preparation and elemental analysis, and particularly relates to a preparation method of a gradient quality control sample for nitrogen element analysis of a nickel-based superalloy. Background Art

[0002] Due to their excellent high-temperature strength, oxidation resistance, corrosion resistance and other excellent properties, superalloys are widely used in the preparation of core components of major equipment such as aerospace, ships and energy. The microstructure and properties of superalloy components are affected by chemical compositions. Therefore, the accurate control and determination of chemical compositions have always been the focus of industry research. Among them, nitrogen element, as an interstitial element and the main element for the formation of nitrides, has a great influence on the properties of superalloys, and its content must be strictly specified within a certain range in various superalloys. The nitrogen element content is mainly determined by the smelting process of the superalloy, but there are significant differences in the control range of the nitrogen element content in different nickel-based superalloys. For example, in the most commonly used GH4169 alloy, the nitrogen element content is 30-60 ppm, and the upper limit is 100 ppm; for disk-type superalloys, the nitrogen element is 10-20 ppm, and the upper limit is 32 ppm; for solution-strengthened nickel-based superalloys, nitrogen element is considered as a strengthening phase beneficial to the strength of the material, and it can be controlled within 100-400 ppm. On the one hand, the nitrogen element can act as an interstitial strengthening element to improve strength and also improve corrosion resistance; on the other hand, it is also an element for the formation of nitrides, and the formed nitride inclusions have an impact on the fatigue performance of the material. Therefore, strict control and rapid and accurate detection of nitrogen elements in various nickel-based superalloys are of great significance for the quality control and cost control of superalloy products.

[0003] The most commonly used and recognized method for nitrogen testing of superalloys is the inert gas fusion thermal conductivity method. This method uses solid direct injection and belongs to a relative method. Therefore, it heavily relies on quality control samples. Calibration curves need to be drawn using a series of quality control samples of the same type, and single-point quality control samples of the same type are used as control samples to correct the test results of the samples to be tested or to control the measurement quality as quality control samples. However, at present, there is a lack of special quality control samples for nitrogen element analysis of superalloys, and standard samples of steel are usually selected in the actual analysis process. There are significant differences between the iron-based components of steel and the commonly used nickel-based components of superalloys, which affects the accuracy of the nitrogen element analysis results of superalloys. However, with the continuous improvement of the quality stability requirements of superalloys for high-end equipment such as aeroengines, the accurate determination of alloy components has become increasingly urgent.

[0004] In order to improve the accuracy of nitrogen analysis of high-temperature alloys by inert gas melting thermal conductivity method, it is urgent to develop a set of high-temperature alloy granular gradient quality control samples of nitrogen to solve the problem of its lack. There are two main difficulties in its preparation. First, due to the complexity of the matrix of high-temperature alloys, multiple smelting is required. As a gas element, nitrogen is difficult to reach the target content in a gradient and accurately. On the other hand, the prepared quality control samples need a more accurate method to determine the composition to ensure the accuracy and traceability of the value, but there is currently a lack of a more accurate determination method for nitrogen. Summary of the invention

[0005] The present invention proposes a method for preparing a gradient quality control sample for analyzing the nitrogen element in a nickel-based high-temperature alloy, which solves the problem of the lack of gradient quality control samples due to the difficulty in accurate gradient control and inability to trace the value of the nitrogen element in the nickel-based high-temperature alloy. The gradient quality control sample of the present invention can accurately analyze the nitrogen element in the nickel-based high-temperature alloy, ensure its traceability, and guarantee the service safety of the nickel-based high-temperature alloy in major equipment.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a gradient quality control sample for nitrogen element analysis of a nickel-based high-temperature alloy, comprising the following steps:

[0008] Taking GH3536 nickel-based superalloy as the matrix, ingots with gradient nitrogen content were prepared. Ingots were named N1 to N5 in descending order according to the nitrogen content. Ingot N1 was GH3536 nickel-based superalloy.

[0009] Performing homogenization treatment on the N1-N5 ingots;

[0010] The ingot subjected to the homogenization treatment is subjected to two upsetting deformation treatments to obtain a rod;

[0011] The bar is surface polished and processed into a specification of 30mm~ For small bars of 100 mm, the uniformity of the small bars is initially inspected at the head, middle and tail positions;

[0012] The small bars that have passed the initial inspection are processed into 6.35mm alternative material;

[0013] Conducting uniformity inspection and fixed value analysis on the candidate materials, wherein the fixed value analysis methods include an inert gas melting thermal conductivity method and a prompt gamma neutron activation analysis k0 standard method;

[0014] When using the gradient quality control sample, the sample weight is >20 mg.

[0015] The nitrogen content in nickel-based superalloys is mainly determined by the smelting process and raw materials. Considering the content control requirements of nitrogen in nickel-based superalloys and the actual usage needs, the present invention selects the GH3536 nickel-based superalloy with a large usage amount as the base material, and the contents of elements (such as Ti, Nb) that are easy to combine with nitrogen in this material are relatively low. Ingots numbered N1 to N5 with different nitrogen contents are prepared, solving the problem that it is difficult to add nitrogen element in a gradient manner during the melting and casting process of nickel-based superalloys, and at the same time solving the problem that nitrogen element is difficult to be uniform. The nitrogen content in the N1 ingot refers to the nitrogen element existing in the raw material (i.e., the GH3536 nickel-based superalloy), and the N2 to N5 ingots are respectively adjusted for nitrogen content by adding high-nitrogen ferrochrome according to weight and content.

[0016] Before homogenizing the N1 to N5 ingots, the following treatments are carried out on the N1 to N5 ingots: Cut off the heads and tails of the N1 to N5 ingots to expose the metallic luster, and there are no visible porosities and shrinkage cavities to the naked eye. After the above-treated ingots are subjected to high-temperature long-term homogenization treatment, the gradient quality control samples can meet the requirements of element uniformity and consistency.

[0017] For the ingots subjected to two upsetting and drawing deformation treatments, their as-cast structures are completely broken, which further promotes the composition uniformity.

[0018] The GH3536 nickel-based superalloy, calculated by mass percentage, includes the following components: Fe: 17% - 20%, Cr: 20.5% - 23%, Mo: 8% - 10%, Co: 0.5% - 2.5%, W: 0.2% - 1%, C: 0.05 - 0.15%, Ti ≤ 0.15%, N ≤ 0.04%, Ni: the balance.

[0019] The preparation step of the ingot with gradient nitrogen content is: Add high-nitrogen ferrochrome to the matrix, and prepare the ingot with gradient nitrogen content by vacuum induction melting.

[0020] The gradient in the ingot with gradient nitrogen content is: The N content in the N1 ingot is 0.0005 - 0.003 wt%, the N content in the N2 ingot is 0.003 - 0.007 wt%, the N content in the N3 ingot is 0.007 - 0.015 wt%, the N content in the N4 ingot is 0.015 - 0.025 wt%, and the N content in the N5 ingot is 0.025 - 0.045 wt%, where the range values of the N content do not include the upper limit endpoint values.

[0021] The steps of the homogenization treatment are: Heat up to 1160 - 1200 °C at a rate of 1 - 10 °C / min, hold for 40 - 80 h, and after the holding ends, cool down to room temperature.

[0022] The deformation temperatures for the two upsetting and drawing deformations are both 1140 - 1160 °C, the heating rates are both 1 - 5 °C / min, the holding times are both not less than 4 h, and the single deformation amounts are both 30 - 60%.

[0023] The bars after the two upsetting and drawing deformations are 32 - 102 mm round bars.

[0024] In the inert gas fusion thermal conductivity method: the analysis power is 5.5 KW, the analysis time is 180 s, and the reference reagent is potassium nitrate (purity > 99.9%).

[0025] The specific method of the prompt gamma neutron activation analysis k0 standard method is as follows: the gradient quality control samples to be measured and potassium chloride are respectively packaged with carbonate, and irradiated with a 14 MeV neutron beam of 7×10 9 n / s for 10 minutes, each is cooled for 2 minutes, the analysis sensitivity ratios of nitrogen element and the comparator are measured in turn, and then the k0 value is obtained by using the wide energy region efficiency calibration curve;

[0026] The comparator is 36 The 1951 KeV γ-ray of 36 Cl.

[0027] Look up according to the wide energy region efficiency calibration curve 36 The 1951 KeV γ-ray emitted by the 36 Cl nuclear reaction and 15 The corresponding of the 1884 KeV γ-ray emitted by the 15 N nuclear reaction Substitute into formula (1) to obtain the k0 value,

[0028] (1)

[0029] Substitute the k0 value into formula (2) to calculate the content of nitrogen (C x )

[0030] (2)

[0031] Among them, the one with x represents the parameters of the element to be measured, and the one with c represents the parameters of the comparator.

[0032] A p , the counting rate per unit weight (Bq / g);

[0033] A sp , the counting rate per unit weight (Bq / μg);

[0034] , the absolute detection efficiency of the full energy peak;

[0035] C x Unit: μg / g.

[0036] The present invention uses the prompt gamma neutron activation analysis single comparator k0 method, selects Cl ( 36 the 1951 KeV γ-ray of Cl) as the single comparator, and uses high-purity potassium chloride (purity of 99.8%) as the standard to achieve the quantitative analysis of nitrogen elements in gradient quality control samples.

[0037] Compared with the prior art, the present invention has the following advantages and technical effects:

[0038] The present invention solves the problem that it is difficult to introduce nitrogen elements in a gradient manner in the field of nickel-based superalloy material preparation. It provides a set of matrix-matched high-temperature alloy-like gradient quality control samples for the determination of nitrogen elements by the inert gas fusion thermal conductivity method (relative method), improves the quality determination system of nitrogen elements in nickel-based superalloys, and ensures the accuracy and traceability of the determination of nitrogen elements in nickel-based superalloy samples.

[0039] The present invention fills the blank of gradient quality control samples for nitrogen elements in nickel-based superalloy samples. Nitrogen element is one of the essential elements to be measured in the testing of nickel-based superalloys. The raw materials of the gradient quality control samples used in the present invention can be prepared repeatedly and at low cost, and can provide reference for the preparation of other gas element quality control samples. Detailed Embodiments

[0040] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0041] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0043] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the specification of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of the present invention are merely exemplary.

[0044] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0045] An embodiment of the present invention provides a method for preparing a gradient quality control sample for nitrogen element analysis of a nickel-based superalloy:

[0046] The nitrogen element content in the nickel-based superalloy is mainly determined by the smelting process and raw materials. Combining the content control requirements and actual usage requirements of nitrogen elements in the nickel-based superalloy, the present invention uses GH3536 nickel-based superalloy as the matrix to prepare ingots with gradient nitrogen element contents, which are named N1 - N5 ingots in order from low to high nitrogen element content. The N1 ingot is GH3536 nickel-based superalloy. The GH3536 nickel-based superalloy, calculated by mass percentage, includes the following components: Fe: 17% - 20%, Cr: 20.5% - 23%, Mo: 8% - 10%, Co: 0.5% - 2.5%, W: 0.2% - 1%, C: 0.05 - 0.15%, Ti ≤ 0.15%, N ≤ 0.04%, Ni: the balance. The present invention designs five ingots with gradient contents, which are named N1 - N5 quality control samples in order from low to high nitrogen element content. The nitrogen content in the N1 ingot refers to the nitrogen element existing in the raw materials (i.e., GH3536 nickel-based superalloy). The N2 - N5 ingots respectively achieve the regulation of nitrogen content by adding high-nitrogen ferrochrome according to weight and content. The N content of the N1 ingot is 0.0005 - 0.003 wt%, the N content of the N2 ingot is 0.003 - 0.007 wt%, the N content of the N3 ingot is 0.007 - 0.015 wt%, the N content of the N4 ingot is 0.015 - 0.025 wt%, and the N content of the N5 ingot is 0.025 - 0.045 wt%. The range values of the N content do not include the upper limit endpoint values, and the expanded uncertainty is given after fully considering factors such as material preparation level, testing level, actual application requirements, and the level of quality control samples with similar compositions at home and abroad. The present invention solves the problem that it is difficult to add nitrogen elements in gradients during the melting and casting process of nickel-based superalloys. When using the gradient quality control sample of the present invention, the sample weighing amount > 20 mg;

[0047] Cut off the heads and tails of ingots N1 to N5, expose the metallic luster, and there are no visible porosities and shrinkage cavities to the naked eye. Perform homogenization treatment on the ingots N1 to N5: heat up at a rate of 1 to 10 °C / min to 1160 to 1200 °C, hold for 40 to 80 h, and after the holding is completed, cool down to room temperature;

[0048] Perform two upsetting and drawing deformation treatments on the homogenized ingots to completely break the as-cast structure and further promote the compositional uniformity, obtaining 32 to 102 mm bars. The deformation temperatures of the two upsetting and drawing deformation treatments are both 1140 to 1160 °C, the heating rates are both 1 to 5 °C / min, the holding times are both not less than 4 h, and the single deformation amounts are both 30 to 60%;

[0049] Turn the surface of the bars to process them into small bars with a specification of 30 mm to 100 mm, and conduct a preliminary inspection of the uniformity at three positions of the head, middle, and tail of the small bars;

[0050] Process the small bars that pass the preliminary inspection into 6.35 mm alternative materials;

[0051] Select 8 units with the qualification of standard sample value determination for value determination analysis. The selected units have passed CNAS recognition or qualification certification and have the ability to test the value determination of standard samples that meet the requirements. In the process of value determination of the gradient quality control sample of nitrogen element in the nickel-based superalloy of the present invention, the inert gas fusion thermal conductivity method (ISO 10720 potassium nitrate reference reagent method) and the prompt gamma neutron activation analysis k0 standard method are used, ensuring the accuracy and traceability of the quantity value.

[0052] In the present invention, "high-nitrogen ferrochrome" refers to high-nitrogen ferrochrome that meets the YB / T 4135-2016 standard. The YB / T 4135-2016 standard stipulates that high-nitrogen ferrochrome is divided into three grades according to the nitrogen content: HNCF10, HNCF15, and HNCF20. Among them, the nitrogen content of HNCF10 is not less than 10%, the nitrogen content of HNCF15 is not less than 15%, and the nitrogen content of HNCF20 is not less than 20%.

[0053] Unless otherwise specified, the room temperature in the present invention is uniformly calculated as 25 ± 2 °C.

[0054] It should be noted that the parts not described in detail in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0055] The technical solutions of the present invention are further described below through examples.

[0056] Example 1

[0057] (1) Using GH3536 nickel-based superalloy (by mass percentage, including the following components: Fe: 18.5%, Cr: 21.8%, Mo: 9%, Co: 1.5%, W: 0.6%, C: 0.08%, Ti: 0.02%, N: 0.0005 - 0.003, Ni: the balance) as the matrix, ingots with gradient nitrogen element content were prepared, named N1 - N5 ingots in ascending order of nitrogen element content. The N1 ingot is GH3536 nickel-based superalloy, and for N2 - N5 ingots, the nitrogen content was regulated by adding 0.3 kg, 0.6 kg, 1.2 kg, and 2.6 kg of HNCF10 high-nitrogen ferrochrome into 600 kg of the matrix respectively. The designed composition content (wt%) and expected uncertainty (%) of N1 - N5 ingots in this example are shown in Table 1;

[0058] Table 1 Designed composition content (wt%) and expected uncertainty (%) of gradient quality control samples

[0059]

[0060] (2) The preparation method of the ingot is as follows: According to the above ratio, the matrix and / or HNCF10 high-nitrogen ferrochrome were added to a vacuum induction melting furnace for smelting to prepare a 305 mm vacuum induction ingot with a single weight of 600 kg. Subsequently, after cutting the head, removing the tail, and turning the surface of the vacuum induction ingot (exposing the metallic luster, without visible porosity and shrinkage to the naked eye), it was subjected to electroslag remelting to obtain an electroslag ingot with a diameter of 406 mm;

[0061] (3) High-temperature homogenization treatment was carried out on the electroslag ingot: It was heated to 1190 °C at a rate of 2 °C / min, held for 60 h, and then cooled to room temperature after the holding was completed to ensure uniform composition;

[0062] (4) The ingot subjected to high-temperature homogenization treatment was subjected to two upsetting and drawing deformation treatments: The first upsetting deformation was 30%, the deformation temperature was 1150 °C, and the holding time was 4 h; the drawing deformation was 30%, the deformation temperature was 1150 °C, and the holding time was 4 h. The second upsetting deformation was 40%, the deformation temperature was 1150 °C, and the holding time was 4 h; the drawing deformation was 40%, the deformation temperature was 1150 °C, and the holding time was 4 h. After the two upsetting and drawing deformation treatments, the intermediate billet was drawn to an 80 mm round bar, the deformation temperature was 1150 °C, and the single deformation was 35%. Subsequently, rolling was carried out, the single-pass drawing deformation was 30%, the deformation temperature was 1150 °C, and the holding time was 4 h to prepare a 33 mm small-sized rolled bar;

[0063] (5) The small-sized rolled bars are surface-turned to process into rolled bars of 30 mm. One rolled bar is taken for composition analysis every three rolled bars. For each rolled bar, composition analysis is carried out at the head, middle, and tail (5 grains are intercepted from each part). The test results are shown in Table 2. The nitrogen element content meets the expected composition design, and the RSD values of the samples are all less than 5%. The rolled bars prepared by the present invention meet the initial inspection analysis of the composition uniformity of the quality control samples and have the conditions for preparing reference materials;

[0064] Table 2 Initial inspection summary table (%)

[0065]

[0066] (6) The 30-mm rolled bars are processed into alternative materials for gradient quality control samples according to 6.35 mm. The packaging material is a high-density polyethylene bottle with a capacity of 15 mL, and each bottle contains 50 grains. The minimum packaging unit number of each sample is 500 bottles. The samples packaged into the minimum packaging units are subjected to homogeneity inspection according to JJF1343-2012 "General Principles and Statistical Principles for the Certification of Reference Materials". Randomly select 20 bottles, number them in sequence as 1-20, and measure them in the following order. Each bottle is measured three times repeatedly.

[0067] First time: 1-3-5-7-9-11-13-15-17-19-2-4-6-8-10-12-14-16-18-20;

[0068] Second time: 20-19-18-17-16-15-14-13-12-11-10-9-8-7-6-5-4-3-2-1;

[0069] Third time: 2-4-6-8-10-12-14-16-18-20-1-3-5-7-9-11-13-15-17-19;

[0070] The determination is carried out by the inert gas fusion thermal conductivity method (refer to GB / T20124-2006). The minimum sample weighing amount is 1.0 g, and the test results are statistically analyzed by the one-way analysis of variance method. All F statistics are less than the F critical value of 1.85, and the requirements for the homogeneity of national reference materials can be met. The test results are shown in Table 3.

[0071] Table 3 Summary of statistical results of homogeneity inspection (%)

[0072]

[0073] (7) In accordance with GB / T15000.1~15000.8 “Guidelines for Standard Samples”, a total of 8 laboratories (referred to as units 1~8) participated in the determination analysis. The determination methods mainly adopted the inert gas fusion thermal conductivity method (ISO 10720 potassium nitrate reference reagent method), the neutron activation method (prompt gamma neutron activation analysis k0 standard method) and the inert gas fusion thermal conductivity method (refer to GB / T20124-2006).

[0074] Inert gas fusion thermal conductivity method (ISO 10720 potassium nitrate reference reagent method):

[0075] The sample weight is 1.0g, the flux is 0.2g nickel foil, the graphite crucible, and the instrument setting parameters are: analysis power 5.5KW, analysis time 180s. The reference reagent (purity>99.9%) potassium nitrate is dried and cooled to room temperature to prepare the calibration curve of nitrogen content (0%~0.05%) shown in Table 4.

[0076] Table 4 Calibration curve of nitrogen content

[0077]

[0078] Neutron activation method (prompt gamma neutron activation analysis k0 standard method):

[0079] Using prompt gamma neutron activation analysis single comparator k0 method, Cl( 36 Cl 1951 KeV γ-ray) as a single comparator, with high-purity potassium chloride as the standard. Accurately weigh 50 mg of the gradient quality control sample to be tested and 1.0 g of high-purity potassium chloride, and pack them in high-purity carbonate, respectively, with 7×10 9 Irradiate with 14MeV neutron beam count rate of n / s for 10 minutes, cool down for 2 minutes respectively, measure the analytical sensitivity ratio of nitrogen element and comparator in turn, and find out according to the wide energy range efficiency calibration curve 36 The 1951KeV gamma rays emitted by the Cl nuclear reaction and 15 The 1884KeV gamma ray emitted by the N nuclear reaction corresponds to Substituting into formula (1), we can obtain the value of k0:

[0080] (1)

[0081] Substituting the k0 value into formula (2) we can calculate the nitrogen content (C x ),

[0082] (2)

[0083] The x's represent the parameters of the element to be measured, and the c's represent the comparator parameters.

[0084] A p , counting rate per unit weight (Bq / g);

[0085] A sp , counting rate per unit weight (Bq / μg);

[0086] , absolute detection efficiency of the full-energy peak;

[0087] C x Unit: μg / g.

[0088] Inert gas fusion thermal conductivity method (refer to GB / T 20124-2006): Select 3 granular standard samples for steel nitrogen analysis (purchased from Shanghai Wugang Co., Ltd., Shanghai Research Institute of Iron and Steel, and Baoshan Iron & Steel Co., Ltd. respectively) to draw the standard curve, and the nitrogen content is between 0.001% and 0.05%. The weighing amount of the standard sample and the sample is 1.0 g, and the instrument setting parameters are: analysis power 5.5 KW, analysis time 180 s.

[0089] Each certifying unit (unit 1-8) and the certification method are shown in Table 5.

[0090] Table 5 Summary of each certifying unit and the certification method

[0091]

[0092] (8) Use the Shapiro-Wilk method to test whether all the data of each unit's certified values obey the normal distribution. Take the average value of the data that obeys the normal distribution as the single determination value, form a new set of data and use the Grubbs method to test, and then use the Cochran method to test whether the data of each group are of equal precision. After processing the data of each group, calculate the arithmetic mean and standard deviation of each group of data. For the significant figure digits of the standard value, round according to GB 8170 "Rules for Rounding off Data". The obtained data is the standard value of the nitrogen element series quality control samples of superalloys, and the results are shown in Table 6.

[0093] Table 6 Standard values and uncertainties (%) of the gradient quality control samples for nitrogen element analysis of nickel-based superalloys

[0094]

[0095] Comparative Example 1

[0096] Same as Example 1, the only difference is that the high-temperature homogenization treatment in step (3) is not carried out.

[0097] When performing the component analysis in step (5), the nitrogen element content at the head and tail of the rolled bar has a large difference, does not meet the uniformity requirement, and the nitrogen of the five contents N1-N5 is not in a gradient.

[0098] Comparative Example 2

[0099] Same as Example 1, except that in step (4), only one upsetting and drawing deformation treatment is performed.

[0100] Perform surface turning in step (5) and machine it into When the rolled bar is 30 mm, the shape of the bar is irregular, and cracks appear in many places on the bar.

[0101] Comparative Example 3

[0102] Same as Example 1, except that in step (7) of the inert gas fusion thermal conductivity method (ISO 10720 potassium nitrate reference reagent method), the instrument analysis power is set to 4.5 KW.

[0103] When performing the determination, although the sample can be completely melted, the nitrogen release curve has a tailing, and the determination result is on the low side.

[0104] Comparative Example 4

[0105] Same as Example 1, except that in step (7) of the neutron activation method, the weighed amount of the gradient quality control sample to be measured is 20 mg.

[0106] When performing the determination, due to the too small weighed amount, the sample uniformity is poor, resulting in poor parallelism of the determination results.

[0107] From the above content, it can be seen that the present invention solves the problem that it is difficult to introduce nitrogen element in a gradient manner in the field of nickel-based superalloy material preparation. It provides a set of matrix-matched high-temperature alloy type gradient quality control samples for the determination of nitrogen element by the inert gas fusion thermal conductivity method (relative method), improves the quality determination system of nitrogen element in high-temperature alloys, ensures the accuracy and traceability of the determination of nitrogen element in high-temperature alloy samples, and at the same time, the present invention fills the blank of nitrogen element gradient quality control samples for nickel-based superalloy samples.

[0108] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A preparation method of a gradient quality control sample for nitrogen element analysis of a nickel-based superalloy, characterized in that, It includes the following steps: Using GH3536 nickel-based superalloy as the matrix, ingots with gradient nitrogen element content are prepared, named ingots N1 to N5 in ascending order of nitrogen element content. Ingot N1 is GH3536 nickel-based superalloy. Perform homogenization treatment on the ingots N1 to N5. Perform two upsetting and drawing deformation treatments on the ingots after the homogenization treatment to obtain bars. Turn and polish the surface of the bar stock to process it into small bar stocks with a specification of 30 mm to 100 mm, and conduct a preliminary inspection of the uniformity at three positions of the head, middle, and tail of the small bar stock; Process the small bar stock that has passed the initial inspection into Alternative material of 6.35 mm; Perform homogeneity inspection and certification analysis on the alternative materials. The methods of the certification analysis include the inert gas fusion thermal conductivity method and the prompt gamma neutron activation analysis k0 standard method. When using the gradient quality control samples, the sample weighing amount > 20 mg. The preparation steps of the ingots with gradient nitrogen element content are as follows: Add high-nitrogen ferrochrome to the matrix and prepare the ingots with gradient nitrogen element content by vacuum induction melting. The gradient in the ingots with gradient nitrogen element content is as follows: The N content of ingot N1 is 0.0005 - 0.003 wt%, the N content of ingot N2 is 0.003 - 0.007 wt%, the N content of ingot N3 is 0.007 - 0.015 wt%, the N content of ingot N4 is 0.015 - 0.025 wt%, and the N content of ingot N5 is 0.025 - 0.045 wt%. The range values of the N content do not include the upper limit endpoints. The steps of the homogenization treatment are as follows: Heat up to 1160 - 1200 °C at a rate of 1 - 10 °C / min, hold for 40 - 80 h, and then cool down to room temperature after the holding ends. The deformation temperatures of the two upsetting and drawing deformation treatments are both 1140 - 1160 °C, the heating rates are both 1 - 5 °C / min, the holding times are not less than 4 h, and the single deformation amounts are both 30 - 60%. In the inert gas fusion thermal conductivity method: The analysis power is 5.5 KW, the analysis time is 180 s, and the reference reagent is potassium nitrate.

2. The preparation method of the gradient quality control sample for nitrogen element analysis of nickel-based superalloy according to claim 1, wherein, The GH3536 nickel-based superalloy, by mass percentage, includes the following components: Fe: 17% - 20%, Cr: 20.5% - 23%, Mo: 8% - 10%, Co: 0.5% - 2.5%, W: 0.2% - 1%, C: 0.05 - 0.15%, Ti ≤ 0.15%, N ≤ 0.04%, and the balance is Ni.

3. The preparation method of the gradient quality control sample for nitrogen element analysis of the nickel-based superalloy according to claim 1, characterized in that, The bar after the above two upsetting and drawing deformations is 32 to a round bar with a diameter of 102 mm.

4. The preparation method of the gradient quality control sample for nitrogen element analysis of the nickel-based superalloy according to claim 1, characterized in that, The specific method of the prompt gamma neutron activation analysis k0 standard method is as follows: The gradient quality control samples to be measured and potassium chloride are respectively packaged with carbonate, and irradiated with a 14 MeV neutron beam of 7×10 9 n / s for 10 minutes, cooled for 2 minutes each, the analysis sensitivity ratios of nitrogen element and comparator are measured in turn, and then the k0 value is obtained by using the wide energy region efficiency calibration curve; The comparator is 36 the 1951 keV γ-ray of Cl.

5. The preparation method of the gradient quality control sample for nitrogen element analysis of the nickel-based superalloy according to claim 1, characterized in that, Find out according to the efficiency calibration curve in the wide energy range 36 the 1951 keV γ-ray emitted by the Cl nuclear reaction and 15 the corresponding 1884 keV γ-ray emitted by the N nuclear reaction Substitute into Equation (1) to obtain the k0 value (1) Substitute the value of k0 into Equation (2) to calculate the nitrogen content (C x ), (2) Among them, those with x represent the parameters of the element to be measured, and those with c represent the parameters of the comparator. A p , the counting rate per unit weight (Bq / g); A sp , the counting rate per unit weight (Bq / μg); , the absolute detection efficiency of the full-energy peak; C x Unit: μg / g.

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