CN107702986B - Method for determining residual life of nickel-based single crystal superalloy - Google Patents

Method for determining residual life of nickel-based single crystal superalloy Download PDF

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CN107702986B
CN107702986B CN201710780127.3A CN201710780127A CN107702986B CN 107702986 B CN107702986 B CN 107702986B CN 201710780127 A CN201710780127 A CN 201710780127A CN 107702986 B CN107702986 B CN 107702986B
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target
determining
metallographic
phase
nickel
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CN107702986A (en
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王心美
岳珠峰
余志远
王新忠
王耀
李磊
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Northwest University of Technology
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Northwest University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/18—Performing tests at high or low temperatures
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/10—Segmentation; Edge detection
    • G06T7/187—Segmentation; Edge detection involving region growing; involving region merging; involving connected component labelling
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/60—Analysis of geometric attributes
    • G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0071—Creep
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/022—Environment of the test
    • G01N2203/0222—Temperature
    • G01N2203/0226—High temperature; Heating means
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10056—Microscopic image
    • G06T2207/10061—Microscopic image from scanning electron microscope
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30108—Industrial image inspection
    • G06T2207/30136—Metal

Abstract

the invention provides a method for determining the residual life of a nickel-based single crystal superalloy, and relates to the technical field of nickel-based superalloys. The method comprises the following steps: providing a reference sample and a target sample of the nickel-based single crystal superalloy; carrying out creep test on a reference sample until the reference sample is fractured, and acquiring a reference metallographic image of the reference sample at a plurality of reference moments, wherein the reference moments comprise the fracture moments and a plurality of previous moments; determining the end point number and the bifurcation point number of the gamma' phase in each reference metallographic picture, and determining the reference connected number of each reference metallographic picture according to the end point number and the bifurcation point number; determining a reference function according to each reference communication number and each reference moment; collecting a target metallographic image of a target sample; determining the end point number and the bifurcation point number of the gamma' phase in the target golden phase diagram, and determining the target connectivity number of the target golden phase diagram according to the end point number and the bifurcation point number; determining a target time corresponding to the target connectivity number according to the target connectivity number and a reference function; and determining the residual life of the target sample according to the target time and the fracture time.

Description

Method for determining residual life of nickel-based single crystal superalloy
Technical Field
The disclosure relates to the technical field of nickel-based high-temperature alloys, in particular to a method for determining the residual life of a nickel-based single crystal high-temperature alloy.
Background
The nickel-based single crystal superalloy is a superalloy taking nickel as a matrix, and is widely applied to parts such as aircraft engines, gas turbine blades and the like due to good high-temperature mechanical properties. The microstructure of a nickel-based single crystal superalloy typically includes a gamma prime phase and a gamma phase, wherein the gamma prime phase is Ni3Al-based intermetallic compound, gamma phase is face-centered cubic structure containing a large amount of solid solution elements, and gamma 'phase is embedded in the gamma phase in a coherent form, and the gamma' phase are the main components of the nickel-based single crystal alloy. In long-term service state, high-temperature creep is failure of nickel-based single crystal superalloyin the main form, in order to avoid failure due to creep rupture, the residual life of the nickel-based single crystal superalloy needs to be predicted.
in the prior art, the residual life can be predicted by analyzing the evolution of the microstructure of the nickel-based single crystal superalloy. Specifically, under the same temperature and stress conditions, the size of the γ' phase and the width of the γ phase can be counted. As the microstructure of the nickel-based single crystal superalloy gradually evolves from an initial state to a complete raft process, the size of a gamma' phase and the width of the gamma phase are in sectional linear changes along with time, and the residual life can be predicted.
However, under some experimental conditions, as time goes by, the completely-rafts microstructure may be decomposed, and since adjacent γ 'phases meet and are connected, and the structures of the γ and γ' phases may become complicated, the conventional method for predicting the residual life is difficult to apply, the difficulty in predicting the residual life is increased, and the accuracy of the result is reduced.
it is to be noted that the information disclosed in the above background section is only for enhancement of understanding of the background of the present disclosure, and thus may include information that does not constitute prior art known to those of ordinary skill in the art.
Disclosure of Invention
It is an object of the present disclosure to provide a method for determining a residual life of a nickel-based single crystal superalloy, thereby overcoming, at least to some extent, one or more of the problems due to limitations and disadvantages of the related art.
According to one aspect of the present disclosure, there is provided a method of determining a residual life of a nickel-based single crystal superalloy, comprising:
Providing a reference sample and a target sample of the nickel-based single crystal superalloy;
Carrying out creep test on the reference sample until the reference sample is fractured, and acquiring a reference metallographic image of the reference sample at a plurality of reference moments, wherein the reference moments comprise fracture moments and a plurality of moments before the fracture moments;
Determining the end point number and the bifurcation point number of the gamma' phase in each reference golden phase map, and determining the reference connection number of each reference golden phase map according to the end point number and the bifurcation point number;
determining a reference function according to each reference connected number and each reference moment;
Collecting a target metallographic image of the target sample;
Determining the end point number and the bifurcation point number of the gamma' phase in the target golden phase diagram, and determining the target connectivity number of the target golden phase diagram according to the end point number and the bifurcation point number;
Determining a target time corresponding to the target connectivity number according to the target connectivity number and the reference function;
And determining the residual life of the target sample according to the target time and the fracture time.
in an exemplary embodiment of the present disclosure, before determining the number of end points and the number of branch points of the γ' phase in each of the reference metallographic diagrams, the method of determining the residual life of the nickel-based single crystal superalloy further includes:
Carrying out binarization on each reference golden phase map;
Filtering the binarized reference golden phase diagram;
and carrying out image refinement on the filtered reference golden phase map.
In an exemplary embodiment of the present disclosure, determining the reference connected component of any one of the reference golden phase diagrams includes:
Calculating a reference connectivity number according to a preset formula, wherein the preset formula is as follows:
NA(γ＇)＝(NT-NTP)/2S；
Wherein: n is a radical ofA(γ') is the reference number of connections, NTis the number of endpoints of the gamma' phase in the reference golden phase diagram, NTPAnd S is the area of the region for counting the gamma' phase end point number and the bifurcation point number in the reference golden phase diagram.
In an exemplary embodiment of the present disclosure, determining the reference function includes:
Establishing a coordinate system with a horizontal axis as time and a vertical axis as a communication number;
Representing each reference connected number and corresponding reference time as a reference coordinate point, wherein the ordinate of each reference coordinate point is the reference connected number, and the abscissa is the reference time;
Fitting each of the reference coordinate points to determine the reference function.
in an exemplary embodiment of the present disclosure, collecting each of the reference golden phase maps comprises:
At each reference moment, cutting a reference metallographic specimen with a preset size on the reference specimen;
And shooting each reference metallographic sample by a microscope at a preset magnification to obtain each reference metallographic picture.
In an exemplary embodiment of the present disclosure, before photographing each of the reference metallographic specimens, acquiring each of the reference metallographic diagrams further includes:
grinding and polishing each reference metallographic specimen;
and corroding each ground and polished reference metallographic specimen.
In an exemplary embodiment of the present disclosure, acquiring the target golden phase map includes:
Intercepting the target metallographic specimen with the preset size from the target specimen;
And shooting the target metallographic specimen by a microscope at the preset magnification to obtain the target metallographic image.
In an exemplary embodiment of the present disclosure, before photographing the target metallographic specimen, acquiring the target metallographic specimen further includes:
grinding and polishing the target metallographic specimen;
And corroding the ground and polished target metallographic specimen.
in an exemplary embodiment of the present disclosure, determining the target connectivity number includes:
calculating the target connected quantity according to a preset formula, wherein the preset formula is as follows:
NA(γ＇)＝(NT-NTP)/2S；
Wherein: n is a radical ofA(γ') is the target connectivity number, NTis the number of endpoints of gamma' phase in the target golden phase diagram, NTPand S is the area of the region for counting the end point number and the branch point number of the gamma' phase in the target golden phase diagram.
In an exemplary embodiment of the present disclosure, the conditions of the creep test include: the test temperature is 980 ℃ and the test stress is 146.67 MPa.
the method for determining the residual life of the nickel-based single crystal superalloy can take the communication number determined according to the number of the end points and the number of the bifurcation points of the gamma' -phase as the characteristic of the microstructure of the nickel-based single crystal superalloy; determining a reference function related to the number of connections and time by analyzing reference metallographic images of a reference sample at a plurality of reference moments; therefore, the target time reflecting the stage of the target sample can be determined according to the reference function and the target connectivity number of the target sample, and further the residual life can be determined according to the fracture time and the target time. Compared with the method for determining the sizes of the gamma 'phase and the gamma phase, the method for determining the number of the end points and the number of the bifurcation points of the gamma' phase is simpler and more convenient to count, so that the difficulty in predicting the residual life can be reduced, and the accuracy of the result is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
drawings
the accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.
FIG. 1 is a flow chart of a method for determining residual life of a nickel-based single crystal superalloy in an exemplary embodiment of the present disclosure.
FIG. 2 is a flow chart of one embodiment of collecting respective reference golden phase maps.
FIG. 3 is a flow diagram of one embodiment of determining a reference function.
FIG. 4 is a flow chart of one embodiment of collecting a target golden phase map.
FIG. 5 is a schematic diagram of one embodiment of preprocessing each reference golden phase map.
FIG. 6 is a schematic diagram of an embodiment of pre-processing a target metallographic image.
Fig. 7 is a reference golden phase diagram obtained in step 120.
Fig. 8 is a reference phase diagram obtained after step 210 and step 220 in fig. 7.
fig. 9 is a reference metallographic image obtained after step 230 of fig. 8.
Fig. 10 is an enlarged view of a portion a in fig. 9.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.
The terms "a," "an," "the," and "said" are used to indicate the presence of one or more elements/components/etc.; the term "comprising" is used in an open-ended inclusive sense and means that there may be additional elements/components/etc. other than the listed elements/components/etc.
In the present exemplary embodiment, a method for determining a residual life of a nickel-based single crystal superalloy is provided for determining a residual life of a target specimen of a nickel-based single crystal superalloy. As shown in fig. 1, the method for determining the residual life of the nickel-based single crystal superalloy according to the present embodiment may include the steps of:
And step S110, providing a reference sample and a target sample of the nickel-based single crystal superalloy.
and S120, performing a creep test on the reference sample until the reference sample is fractured, and acquiring a reference metallographic of the reference sample at a plurality of reference moments, wherein the reference moments comprise the fracture moment and a plurality of previous moments.
And step S130, determining the end point number and the bifurcation point number of the gamma' phase in each reference golden phase map, and determining the reference connection number of each reference golden phase map according to the end point number and the bifurcation point number.
Step S140, determining a reference function according to each reference connected quantity and each reference time.
And S150, collecting a target metallographic image of the target sample.
And step S160, determining the end point number and the bifurcation point number of the gamma' phase in the target golden phase diagram, and determining the target connectivity number of the target golden phase diagram according to the end point number and the bifurcation point number.
and S170, determining target time corresponding to the target connectivity number according to the target connectivity number and the reference function.
And S180, determining the residual life of the target sample according to the target time and the fracture time.
In the method for determining the residual life of the nickel-based single crystal superalloy in the exemplary embodiment, the connectivity number is taken as the characteristic of the microstructure of the nickel-based single crystal superalloy, so that statistics is facilitated; determining a reference function for the number of connections and time by analyzing reference golden phase diagrams of the reference sample at a plurality of reference times; therefore, the target time reflecting the stage of the target sample can be determined according to the reference function and the connectivity number of the target sample, and further the residual life can be determined according to the fracture time and the target time. Compared with the method for determining the sizes of the gamma 'phase and the gamma phase, the method for determining the number of the end points and the number of the bifurcation points of the gamma' phase is simpler and more convenient to count, so that the difficulty in predicting the residual life can be reduced, and the accuracy of the result is improved.
Hereinafter, the respective steps of the method for determining the residual life of the nickel-based single crystal superalloy in the exemplary embodiment of the present disclosure will be further described.
In step S110, a reference sample and a target sample of a nickel-based single crystal superalloy are provided.
The above-mentioned nickel-based single crystal superalloy may be in an as-cast state, but is not limited thereto, and it may be composed of C, Cr, Co, W, Mo, Ta, Al, Hf, B, Re, Y, and Ni, and of course, may include other components. Wherein the mass percentages of the elements are respectively as follows: c: 0.059%; cr: 7.00 percent; co: 7.83 percent; w: 5.01 percent; mo: 1.52 percent; ta: 6.51 percent; al: 6.01 percent; hf: 0.11 percent; b: 0.004%; re: 3.08 percent; y: 0.016 percent; the balance being Ni; however, the mass percentages of the elements are not limited to the above ratios, and other ratios may be used. The reference sample and the target sample may be both flat plate structures having the same size, or may be cylindrical or "i" shaped structures. Further, the reference and target specimens may have an axial direction that is at an angle of no more than 12 °, such as 8 °, 10 °, etc., to the crystal orientation of the nickel-based single crystal superalloy. The crystal orientation can be [001] orientation, [110] orientation or [111] orientation, and the like, and the crystal orientation of the existing nickel-based single crystal superalloy can be referred to specifically, and is not detailed herein.
In step S120, a creep test is performed on the reference sample until the reference sample is fractured, and a reference metallographic image of the reference sample is acquired at a plurality of reference times, wherein the reference times include the fracture time and a plurality of previous times.
The creep test may be performed at a test temperature of 980 ℃ and a test stress of 146.67MPa, but not limited thereto, and both the test temperature and the test stress may be greater or smaller. The creep test can be carried out by adopting a creep testing machine to carry out the creep test on the reference sample in a unidirectional stretching mode, and the test is stopped until the reference sample is broken. The reference time may include a plurality of times before the reference specimen breaks, for example, it may be a time when the creep test is performed up to 494.2 hours. Meanwhile, the reference time also includes the time at which the reference sample is broken, i.e., the breaking time. The specific number of reference times is not particularly limited, and may be 8, 10, etc.
Each reference metallographic image is used to reflect the microstructure of the reference sample at the corresponding time, and the reference metallographic image may be an image of a certain region of the reference sample after being magnified by a predetermined magnification factor, based on which the γ' phase and the γ phase can be observed in the reference metallographic image, and is not particularly limited herein.
For example, the creep test may be performed at a test temperature of 980 ℃ and a test stress of 146.67Mpa, with the time from the test time to the 494.2 th hour as a reference time, and a reference metallographic image of the reference sample is acquired at the reference time, as shown in fig. 7, which is shown in fig. 7.
As shown in fig. 2, the method for acquiring each reference golden phase map may include steps S1201 to S1204, where:
In step S1201, a reference metallographic specimen of a predetermined size may be cut out on the reference specimen at each reference timing.
Specifically, the creep test may be suspended at each reference time and at the time of fracture, and during the suspension, a region having a length of 5mm may be cut out on the reference specimen using a wire cutting machine as a reference metallographic specimen, so that the reference metallographic specimen corresponding to each time may be produced. The time of pause is not particularly limited herein, provided that it is sufficient to intercept the reference metallographic specimen. The length of the cut is not limited to 5mm, but may be larger or smaller.
In step S1202, each reference metallographic specimen may be ground and polished. So as to make the surface of the reference metallographic specimen more flat.
the method can be used for firstly grinding each reference metallographic specimen by using sand paper so as to grind the surface of the reference specimen and remove damage and a deformation layer brought by the cutting and intercepting process of the specimen. And polishing the ground reference metallographic specimen by using the grinding paste, and removing grinding marks left on the ground surface of the reference metallographic specimen to obtain a mirror-like surface which is ready for displaying a microstructure. The types of sandpaper and abrasive paste are not particularly limited herein. Of course, the above-mentioned grinding and polishing process may be performed by using a special grinding machine or the like.
in step S1203, each of the ground and polished reference metallographic specimens is etched. In order to observe the microstructure of the reference metallographic specimen.
the reference metallographic specimen can be corroded by a chemical corrosion method, namely the reference metallographic specimen is corroded by corrosive liquid, wherein the corrosive liquid can be prepared from nitric acid, hydrofluoric acid and glycerol according to the proportion of 1:2: 3. Of course, the components and the proportion of the etching solution are not limited to these, and etching solutions of other components and proportions may be used. Meanwhile, the corrosion time of each reference metallographic specimen can be controlled to be the same, so that the same corrosion degree of the surfaces of different reference metallographic specimens is ensured. In addition, other methods such as electrolytic etching may be used for the etching of the reference metallographic specimen, and details thereof will not be described.
In step S1204, each reference metallographic specimen may be photographed by a microscope at the above-described predetermined magnification to obtain each reference metallographic specimen.
The predetermined magnification may be 5000 times, but is not limited thereto, and may be greater or less than 5000 times. The microscope device may be a scanning electron microscope, and the principle and the use method of the scanning electron microscope may refer to the existing scanning electron microscope and are not described in detail herein. The microscopic means may also employ other microscopic devices as long as images can be taken that enable observation of the microstructure of the reference metallographic specimen. The reference golden phase map may be in TIFF format or JPEG format, but may be in other formats.
it should be noted that the above method for acquiring each reference golden phase diagram may not include step S1202 and step S1203, or may further include other steps, which are not described in detail herein. In addition, in other example embodiments of the present disclosure, the respective reference golden phase diagrams may also be acquired by other methods, which are not listed here.
in step S130, determining the number of end points and the number of branch points of the γ' phase in each reference golden phase map, and determining the reference connectivity number of each reference golden phase map according to the determined number;
In any of the reference metallographic pictures, the γ ' phase may have an end point, which is the end of the γ ' phase where no branching occurs, and a branch point, which is the intersection point of the branches formed by the branching of the γ ' phase. Meanwhile, for any reference golden phase diagram, the end point number and the bifurcation point number of the gamma' phase in the reference golden phase diagram can be obtained by counting in a certain area of the reference golden phase diagram; meanwhile, the γ 'facies for the boundary positions of the reference golden phase map may not be counted because points at the boundary of the reference golden phase map may be formed due to truncation of the γ' facies by the boundary, and are not true endpoints or bifurcation points.
determining the reference connectivity number for any of the reference golden phase plots may include: the reference number of connections is calculated according to the following formula, which may be:
NA(γ＇)＝(NT-NTP)/2S；
wherein: n is a radical ofA(γ') denotes the reference number of connections, NTDenotes the number of endpoints of the gamma' phase in the reference metallographic picture, NTPthe number of bifurcation points of gamma' phase in the reference golden phase diagram is shown, S represents the statistic NTand NTPThe area of the region (d).
For example, in a reference golden phase diagram, NTIs 173, NTP131, S466.59 μm2Substituting into the above preset formula to obtain NA(gamma') was 0.045 μm-2That is, the reference connectivity number of the reference golden phase diagram is 0.045 μm-2。
The reference connected number can be determined by adopting the mode for each reference golden phase diagram, and of course, the reference connected number can also be determined by adopting other modes. Meanwhile, in the reference golden phase diagram, the gamma' phase may have statistics of end points and branch points, which may be manual statistics, or may be automatically obtained through software by using the existing image recognition and feature acquisition technology, so as to improve the working efficiency, and will not be described in detail herein.
In step S140, a reference function is determined based on each reference connectivity number and each reference time.
The reference function can reflect the corresponding relation between each reference connected number and each corresponding reference time. As shown in fig. 3, the method of determining the reference function may include steps S1401 to S1403, wherein:
In step S1401, a coordinate system in which the horizontal axis is time and the vertical axis is the number of connected components is established.
the horizontal axis of the coordinate system at least comprises scales corresponding to each reference moment; the longitudinal axis includes at least a scale corresponding to each reference communication number.
In step S1402, each reference connected component and the corresponding reference time are expressed as reference coordinate points, the ordinate of each reference coordinate point is the reference connected component, and the abscissa is the reference time.
Any reference golden phase diagram has a corresponding set of reference connected numbers and a reference time, which may be the fracture time or a previous time. The time corresponding to the reference golden phase diagram may be taken as an abscissa and the corresponding reference connected number as an ordinate, thereby determining a reference coordinate point with respect to the reference golden phase diagram. In this way, reference coordinate points corresponding to the respective reference golden phase maps can be determined, each of which can be marked in the above-mentioned coordinate system.
In step S1403, each reference coordinate point is fitted to determine a reference function.
Connecting the reference coordinate points to form a curve; determining a known function with a plurality of coefficients to be determined according to the shape of the curve; the undetermined coefficient can be determined by substituting each coordinate point into the known function, and the known function is the reference function at the moment.
for example, if the known function is a power function y ═ kxaThe reference coordinate points include (x)1，y1)、(x2、y2) And (x)3、y3) Etc., substituting the coordinates of each reference coordinate point into y ═ kxaRespectively obtain y1＝k x1 a、y2＝k x2 aAnd y3＝k x3 aSo that the values k, k ' and a, a ' can be calculated, and finally y, k ', x, can be determineda＇and this is taken as the reference function.
It should be noted that the above power function is only an exemplary one, and is intended to illustrate the process of determining the reference function by fitting, and the specific type of the reference function may be determined according to the shape of the curve formed by connecting the reference coordinate points, and the type is not particularly limited herein.
In step S150, a target metallographic image of a target sample is acquired. The target sample is a nickel-based single crystal superalloy sample which is not fractured under the same experimental conditions, and has the same specification as a reference sample.
The specific method for collecting the target golden phase diagram can refer to the method for collecting the reference golden phase diagram. For example, as shown in fig. 4, the method for acquiring a target golden phase map may include steps S1501 to S1504, where:
In step S1501, a target metallographic specimen of a predetermined size is cut out of the target metallographic specimen.
In step S1502, the target metallographic specimen is ground and polished;
in step S1503, the ground and polished target metallographic specimen is corroded by a corrosive solution.
in step S1504, the target metallographic specimen is photographed by a microscope at a predetermined magnification to obtain a target metallographic image.
It should be noted that the method for acquiring the target golden phase diagram may not include step S1502 and step S1503, or may further include other steps, which are not described in detail herein. Meanwhile, the step S150 may be performed independently from the above steps S120 to S140, and is not limited to be performed after the step S140, for example, the step S150 may be performed simultaneously with the step S120. In addition, in other example embodiments of the present disclosure, the target golden phase diagram may also be acquired by other methods, which are not listed here.
In step S160, the number of end points and the number of branch points of the γ' phase in the target golden phase map are determined, and the target connected number of the target golden phase map is determined based on the determined end points and branch points.
The method for determining the number of end points and the number of branch points of the γ 'phase in the target golden phase map may refer to the above-described method for determining the number of end points and the number of branch points of the γ' phase in the reference golden phase map, and will not be described in detail herein. Meanwhile, the method for determining the reference connectivity number may be referred to for determining the target connectivity number of the target golden phase map, that is, the number of end points and the number of branch points of the γ' phase in the target golden phase map may be substituted into the preset formula, that is:
NA(γ＇)＝(NT-NTP)/2S；
wherein: n is a radical ofA(γ') represents the number of target connections, NTdenotes the number of endpoints of the gamma' phase in the target metallographic picture, NTPThe number of bifurcation points of gamma' phase in the target golden phase diagram is shown, S represents the statistic NTAnd NTPThe area of the region (d).
In other example embodiments of the present disclosure, the target connected number of the target golden phase diagram may also be determined in other manners, and will not be described in detail herein.
In step S170, a target time corresponding to the target number of connected components is determined based on the target number of connected components and the reference function.
Since the reference function reflects the relationship between the number of connected components and the time of the creep test, the target number of connected components can be substituted into the reference function, and the time corresponding to the target number of connected components, that is, the target time can be calculated. Since the target specimen is not fractured, the target time is a time before the fracture time. Since the reference sample and the target sample are two samples of the same material and standard, the current target sample can be regarded as the reference sample when the creep test is performed to the target time.
in step S180, the residual life of the target specimen is determined from the target time and the fracture time.
The residual life of the target sample is the time length between the target moment and the breaking moment, so that the residual life of the target sample can be accurately calculated. For example, the target time is the time from the creep test to the 400 th hour, and the fracture time is the 2000 th hour, and the residual life is 1600 hours.
In an exemplary embodiment of the present disclosure, before determining the number of end points and the number of branch points of the γ' phase in each reference metallographic image, as shown in fig. 5, the method for determining the residual life of the nickel-based single crystal superalloy may further include a step of preprocessing each reference metallographic image, i.e., step S210 to step S230, in which:
In step S210, each reference golden phase map may be binarized.
A threshold value of the gray scale value may be set, and the threshold value may be any value greater than 0 and less than 255, such as 127. The gray value of each pixel point of the reference golden picture can be compared with the threshold value, the gray value of the reference golden picture is divided into two parts which are larger than the threshold value and smaller than the threshold value, and the two parts are displayed in a black color (the gray value is 0) and a white color (the gray value is 255) in a distinguishing mode. Thereby making the gamma' phase more clear in the reference golden phase diagram.
for example, for any reference golden picture, the gray level of each pixel of the reference golden picture can be compared with 127; setting the gray value of the pixel point with the gray value larger than 127 as 0 (255); the gradation value of the pixel point whose gradation value is smaller than 127 is set to 255 (0). The detailed process can refer to the existing image binarization processing process, and is not detailed here.
In step S220, the binarized reference golden phase map is filtered. As shown in fig. 8, fig. 8 shows the reference golden phase diagram obtained after the reference golden phase diagram in fig. 7 goes through steps 210 and 220.
The binarized reference golden phase image can be filtered by a median filtering method, noise points are eliminated, the definition degree of the reference golden phase image is further improved, and the specific process of median filtering can refer to the existing median filtering method and is not detailed here. Of course, the filtering method is not limited to median filtering, and other filtering methods that achieve the same effect may also be used, and are not listed here.
In step S230, the filtered reference golden phase map is subjected to image refinement. As shown in fig. 9 and 10, fig. 9 shows the reference golden phase diagram obtained after the step 230 of the reference golden phase diagram in fig. 8. Fig. 10 is an enlarged view of fig. 9, and the boxes in fig. 10 show the positions of the end points of the γ 'phase, and the circles show the positions of the branch points of the γ' phase.
The filtered image can be refined by an iterative refinement algorithm or a non-iterative refinement algorithm, that is, the binarized and filtered reference golden phase image is skeletonized so as to make the gamma' phase in the reference golden phase image clearer. The specific process of image refinement can refer to the existing image refinement technology, and is not detailed here.
The steps of preprocessing each reference golden phase map, namely step S210 to step S230, can be realized by image software to improve the working efficiency.
In an exemplary embodiment of the present disclosure, before determining the number of end points and the number of branch points of the γ' phase in the target metallographic phase, the method for determining the residual life of the nickel-based single crystal superalloy may further include a step of preprocessing the target metallographic phase, which may be referred to in particular as the step of preprocessing the reference metallographic phase, for example, as shown in fig. 6, the step of preprocessing the target metallographic phase may include steps S310 to S330, where:
In step S310, the target golden phase map may be binarized.
In step S320, the binarized target golden phase map is filtered.
In step S330, the filtered target golden phase map is subjected to image refinement.
other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims (10)

1. a method for determining residual life of a nickel-based single crystal superalloy, comprising:
Providing a reference sample and a target sample of the nickel-based single crystal superalloy;
carrying out creep test on the reference sample until the reference sample is fractured, and acquiring a reference metallographic image of the reference sample at a plurality of reference moments, wherein the reference moments comprise fracture moments and a plurality of moments before the fracture moments;
determining the end point number and the bifurcation point number of the gamma' phase in each reference golden phase map, and determining the reference connection number of each reference golden phase map according to the end point number and the bifurcation point number;
Determining a reference function according to each reference connected number and each reference moment;
Collecting a target metallographic image of the target sample;
Determining the end point number and the bifurcation point number of the gamma' phase in the target golden phase diagram, and determining the target connectivity number of the target golden phase diagram according to the end point number and the bifurcation point number;
Determining a target time corresponding to the target connectivity number according to the target connectivity number and the reference function;
And determining the residual life of the target sample according to the target time and the fracture time.
2. the method for determining the residual life of a nickel-based single crystal superalloy as claimed in claim 1, wherein the method for determining the residual life of a nickel-based single crystal superalloy further comprises, before determining the number of end points and the number of branch points of a γ' phase in each of the reference metallographic images:
carrying out binarization on each reference golden phase map;
Filtering the binarized reference golden phase diagram;
And carrying out image refinement on the filtered reference golden phase map.
3. The method of determining the residual life of a nickel-based single crystal superalloy as in claim 1, wherein determining the reference connectivity number for any of the reference metallographic maps comprises:
Calculating a reference connectivity number according to a preset formula, wherein the preset formula is as follows:
NA(γ＇)＝(NT-NTP)/2S；
wherein: n is a radical ofA(γ') is the reference number of connections, NTIs the number of endpoints of the gamma' phase in the reference golden phase diagram, NTPThe number of the branching points of the gamma 'phase in the reference golden phase diagram, and S is the region for counting the number of the gamma' phase end points and the branching points in the reference golden phase diagramThe area of (a).
4. the method of determining the residual life of a nickel based single crystal superalloy as in claim 1, wherein determining the reference function comprises:
Establishing a coordinate system with a horizontal axis as time and a vertical axis as a communication number;
representing each reference connected number and corresponding reference time as a reference coordinate point, wherein the ordinate of each reference coordinate point is the reference connected number, and the abscissa is the reference time;
Fitting each of the reference coordinate points to determine the reference function.
5. the method for determining the residual life of the nickel-based single crystal superalloy according to any of claims 1 to 4, wherein collecting each of the reference metallographic images comprises:
At each reference moment, cutting a reference metallographic specimen with a preset size on the reference specimen;
and shooting each reference metallographic sample by a microscope at a preset magnification to obtain each reference metallographic picture.
6. The method for determining the residual life of the nickel-based single crystal superalloy as in claim 5, wherein collecting each of the reference metallographic graphs further comprises, before photographing each of the reference metallographic samples:
Grinding and polishing each reference metallographic specimen;
And corroding each ground and polished reference metallographic specimen.
7. The method for determining the residual life of a nickel-based single crystal superalloy as in claim 5, wherein collecting the target metallographic image comprises:
Intercepting the target metallographic specimen with the preset size from the target specimen;
And shooting the target metallographic specimen by a microscope at the preset magnification to obtain the target metallographic image.
8. The method for determining the residual life of the nickel-based single crystal superalloy as in claim 7, wherein collecting the target metallographic specimen before photographing the target metallographic specimen further comprises:
Grinding and polishing the target metallographic specimen;
And corroding the ground and polished target metallographic specimen.
9. The method of determining the residual life of a nickel based single crystal superalloy as in claim 1, wherein determining the target connectivity number comprises:
calculating the target connected quantity according to a preset formula, wherein the preset formula is as follows:
NA(γ＇)＝(NT-NTP)/2S；
Wherein: n is a radical ofA(γ') is the target connectivity number, NTIs the number of endpoints of gamma' phase in the target golden phase diagram, NTPand S is the area of the region for counting the end point number and the branch point number of the gamma' phase in the target golden phase diagram.
10. the method for determining the residual life of a nickel based single crystal superalloy as claimed in claim 1, wherein the creep test conditions comprise: the test temperature is 980 ℃ and the test stress is 146.67 MPa.
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CN110018068A (en) * 2019-04-03 2019-07-16 西北工业大学 Based on the nickel-based monocrystal Blade Properties appraisal procedure for directly cutting microspecimen
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