Inspection method for G115 martensite heat-resistant steel pipe
By combining optical and electron microscopy, tungsten-rich phases were examined in G115 steel pipes. Judgment criteria for different smelting methods were established, which solved the problem that existing technologies could not effectively detect tungsten-rich phase anomalies, and improved the accuracy and safety of the examination.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DATANG YUNCHENG POWER GENERATION CO LTD
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies cannot effectively screen out the abnormal distribution of tungsten-rich phases in G115 steel pipes, leading to potential failure risks. Existing standards only cover conventional mechanical properties and cannot ensure the creep performance and long-term service safety of steel pipes.
The G115 martensitic heat-resistant steel pipe was inspected for tungsten-rich phase using a combination of optical microscopy and electron microscopy. Judgment criteria for different smelting methods were established, including optical microscopy and electron microscopy inspection criteria. The initial inspection results were determined by optical microscopy observation, and the inspection results were further confirmed under electron microscopy.
This technology enables targeted and systematic inspection of G115 steel pipes, effectively detects tungsten-rich phase anomalies, improves the accuracy of inspection, avoids potential failure risks, and ensures the safety of steel pipes.
Smart Images
Figure CN122016899A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of metal material testing technology, and in particular to a testing method for G115 martensitic heat-resistant steel pipes. Background Technology
[0002] G115 (08Cr9W3Co3VNbCuBN) steel is a new generation of martensitic heat-resistant steel. Due to its excellent high-temperature creep strength, creep resistance, and microstructural stability, it is widely used in high-temperature components of supercritical power plant boilers, such as large-diameter thick-walled steel pipes. In G115 steel, tungsten (W) is an important solid solution strengthening and precipitation strengthening element, but it may form tungsten-rich phases, such as the Laves phase, during solidification and subsequent heat treatment. The size, morphology, distribution, and quantity of these tungsten-rich phases significantly affect the mechanical properties of the steel, especially its toughness and creep resistance, thus impacting the creep performance and long-term service safety of the steel pipe.
[0003] Currently, the inspection of G115 steel pipes relies on existing standards such as T / CSTM 00017 and Q / OAPD 2253, which only cover conventional mechanical properties and microstructure testing. Therefore, relying on existing standards to inspect G115 steel pipes may result in abnormal distribution of tungsten-rich phases inside the pipes, even if the conventional mechanical properties are qualified. Existing technology cannot effectively screen out defective pipes with qualified conventional properties but abnormal tungsten-rich phases, leading to potential failure risks for G115 steel pipes. Summary of the Invention
[0004] To address the aforementioned problems in the existing technology, this application provides a testing method for G115 martensitic heat-resistant steel pipes. The technical problem to be solved by this application is achieved through the following technical solution: This application provides a testing method for G115 martensitic heat-resistant steel pipes, comprising the following steps: Prepare the sample of the steel pipe to be inspected; The sample to be tested was observed under a light microscope to determine the target testing area, which is the region where the tungsten-rich phase is located. Based on the smelting method of the steel pipe to be inspected, determine the optical microscopy inspection standard and electron microscopy inspection standard corresponding to the smelting method; Based on the first metallographic information and optical microscopy inspection standards within the target inspection area, the initial inspection results of the steel pipe to be inspected are determined. If the initial inspection results are satisfactory, the target inspection area will be observed under an electron microscope. Based on the second metallographic information and electron microscopy inspection standards within the target inspection area, the inspection results of the steel pipe to be inspected are determined.
[0005] In one feasible approach, the smelting methods include: electroslag smelting and non-electroslag smelting.
[0006] In one feasible approach, the initial inspection result of the steel pipe to be inspected is determined based on the first metallographic information and optical microscopy inspection standards within the target inspection area, specifically including: Obtain the first metallographic information within the target inspection area, including the distribution morphology of the tungsten-rich phase under light microscopy. When the distribution pattern is discrete, the initial inspection result of the steel pipe to be inspected is deemed qualified. Discrete distribution refers to the independent distribution of several tungsten-rich phase particles. When the distribution pattern is clustered, the initial inspection result of the steel pipe to be inspected is determined based on the number of clusters, cluster length, and the first optical microscope inspection standard. When the distribution pattern is discontinuous along the grain boundary or continuous, the initial inspection result of the steel pipe to be inspected is determined according to the distribution length and the second light microscope inspection standard.
[0007] In one feasible approach, the first light microscope inspection criteria include: number of clusters ≤ X, cluster length ≤ Yµm; The second light microscope testing standard includes: distribution length ≤ Qµm; When the steel pipe to be inspected is smelted by electroslag smelting, X=1, Y=80, Q=40; When the steel pipe to be inspected is smelted by non-electroslag smelting, X=3, Y=150, Q=50.
[0008] In one feasible approach, the inspection result of the steel pipe to be inspected is determined based on the second metallographic information and electron microscopy inspection standards within the target inspection area, specifically including: Obtain second metallographic information within the target inspection area, including the distribution morphology of the tungsten-rich phase under electron microscopy. When the distribution pattern is discrete or clustered, the inspection result of the steel pipe to be inspected is determined according to the particle size of the tungsten-rich phase and the first electron microscopy inspection standard. When the distribution pattern is discontinuous along the grain boundary or continuous, the inspection result of the steel pipe to be inspected is determined according to the distribution length and the second electron microscopy inspection standard.
[0009] In one feasible approach, the first electron microscopy inspection criteria include: tungsten-rich phase particle size ≤ Fµm, and the proportion of tungsten-rich phase particles with size Eµm~Fµm ≤ 30%; The second electron microscopy testing standard includes: distribution length ≤ Qµm; When the steel pipe to be inspected is smelted by electroslag smelting, E=2, F=3, Q=40; When the steel pipe to be inspected is smelted by non-electroslag smelting, E=2, F=5, Q=50.
[0010] In one feasible manner, the preparation of the test sample of the steel pipe to be inspected includes: Take at least two samples from the steel pipe to be inspected; The inspection surface of the sample is pretreated to obtain the inspection sample of the steel pipe to be inspected.
[0011] In one feasible approach, the test surface of the specimen is a plane parallel to the radial surface of the steel pipe to be tested.
[0012] In one feasible manner, one of the at least two samples is taken from the inner wall of one end of the steel pipe to be tested.
[0013] In one feasible approach, the pretreatment includes sequential grinding, polishing, and etching.
[0014] Compared with the prior art, the beneficial effects of this application are as follows: The inspection method for G115 martensitic heat-resistant steel pipes provided in this application uses optical microscopy and electron microscopy to inspect the steel pipes for tungsten-rich phases, and formulates targeted judgment criteria for different smelting methods of the steel pipes to achieve targeted and systematic judgment of the steel pipes' qualification, avoids potential failure risks caused by abnormal tungsten-rich phases, effectively detects defective steel pipes, and improves inspection accuracy. Attached Figure Description
[0015] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of the steps of an inspection method for G115 martensitic heat-resistant steel pipe provided in an embodiment of this application; Figures 2a-2d This is an optical microscope image of the G115 martensitic heat-resistant steel pipe provided in the embodiments of this application; Figures 3a-3b This is a scanning electron microscope image of the G115 martensitic heat-resistant steel pipe provided in the embodiments of this application. Detailed Implementation
[0016] The following description, in conjunction with the accompanying drawings, details a testing method for G115 martensitic heat-resistant steel pipes provided by this application through specific embodiments and application scenarios. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Unless otherwise specified, the following embodiments and features can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.
[0017] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.
[0018] Please see Figure 1 , Figure 1 This is a flowchart illustrating the steps of a method for testing the tungsten-rich phase in a G115 martensitic heat-resistant steel pipe, as provided in an embodiment of this application.
[0019] This embodiment provides a testing method for G115 martensitic heat-resistant steel pipes, comprising the following steps: S1: Prepare the sample of the steel pipe to be inspected.
[0020] Specifically, in the actual production process of the factory, each batch of steel pipes consists of steel pipes with the same heat number, the same specification, and the same heat treatment regime (heat number), and the number of steel pipes in each batch is no more than 10. Therefore, a sampling inspection method is adopted to select steel pipes to be inspected from each batch to determine whether the batch of steel pipes is qualified. In this embodiment, the preparation of the inspection sample of the steel pipes to be inspected includes: S11: Take at least two samples from the steel pipe to be inspected.
[0021] In this embodiment, the steel pipe to be inspected is a G115 martensitic heat-resistant steel pipe with an outer diameter greater than 219 mm that has undergone final heat treatment, and the steel pipe to be inspected conforms to the T / CSTM 00017-2021 or Q / OAPD 2253-2022 standards. Specifically, one of the at least two samples is taken from the inner wall of one end of the steel pipe to be inspected, and the other sample can be taken from any wall thickness or the outer wall of the steel pipe to be inspected. The sample size is 10 mm to 15 mm long along the wall thickness direction of the steel pipe to be inspected, and 15 mm to 20 mm long along the longitudinal direction of the steel pipe to be inspected.
[0022] Specifically, since the inner wall of the steel pipe under inspection is more prone to segregation, shrinkage cavities, inclusion accumulation, decarburization, or abnormal structure than the outer wall, sampling is performed on the inner wall of the steel pipe under inspection. If the sample taken from the inner wall passes the inspection, it can be determined that any wall thickness inside the steel pipe and the outer wall are definitely qualified.
[0023] S12: Pre-treat the inspection surface of the sample to obtain the inspection sample of the steel pipe to be inspected.
[0024] In this embodiment, the inspection surface of the sample is a plane parallel to the radial surface of the steel pipe to be inspected. Furthermore, the pretreatment includes sequential grinding, polishing, and etching.
[0025] Specifically, the test surface of the sample is ground and polished according to the conventional metallographic sample preparation method specified in GB / T 13298. Then, an etchant is used to etch the test surface to obtain the sample to be tested. The preferred etchant is a ferric chloride hydrochloric acid aqueous solution of FeCl3:HCl:H2O = 10g:30ml:120ml, but other etchants commonly used in martensitic heat-resistant steels can also be selected.
[0026] In one feasible manner, step S1 includes: A batch of G115 steel pipes with an outer diameter of 860 mm and a wall thickness of 40 mm, produced using electroslag smelting technology and having undergone final heat treatment, was subjected to tungsten-rich phase testing. This batch consisted of four pipes with identical furnace numbers, specifications, and heat treatment regimes. One pipe was selected from this batch as the test pipe. Two test samples were taken from the first end of the test pipe, one at the inner wall and the other at 1 / 2 wall thickness (i.e., 20 mm from the outer surface). Each test sample was cut to a length of 12 mm along the wall thickness direction and 18 mm longitudinally along the test pipe. The test surface was a plane parallel to the radial direction of the test pipe. The test surfaces of both samples were ground with W2.5 diamond polishing paste according to the GB / T 13298 metallographic sample preparation standard, and then mechanically polished. After polishing, the test surface is etched with a ferric chloride hydrochloric acid aqueous solution. This creates selective contrast in the fine details of the sample's microstructure, allowing for clear revelation of the sample's microstructure under an optical microscope, thus obtaining the sample to be tested. In this embodiment, the etching time is 10 to 20 seconds.
[0027] S2: Perform light microscopic observation on the sample to determine the target inspection area, which is the region where the tungsten-rich phase is located.
[0028] Specifically, after etching the inspection surface, it is observed under an optical microscope at 100x to 1000x magnification. The target inspection area is determined based on the distribution of the tungsten-rich phase throughout the inspection surface. Further, the inspection surface contains both tungsten-poor and tungsten-rich phases. The target inspection area is the optical microscope field of view where the tungsten-rich phase is located. Optionally, the target inspection area is the optical microscope field of view where the tungsten-rich phase is clustered, discontinuously distributed along grain boundaries, or continuously distributed; or, the optical microscope field of view where the tungsten-rich phase is discretely distributed and has the highest number of tungsten particles.
[0029] Furthermore, the discrete distribution means that several tungsten-rich phase particles exhibit an independent and uniform spatial distribution characteristic. The cluster distribution refers to the aggregation of tungsten-rich phase particles rather than uniform dispersion. The cluster distribution includes linear cluster distribution and cluster distribution, which appear as multiple particles closely packed together under an optical microscope and are sparse in other areas. The discontinuous grain boundary distribution means that the tungsten-rich phase mainly appears near the grain boundaries but the distribution is discontinuous, showing a punctate, chain-like or sporadic intermittent arrangement, and appears as small particles distributed at intervals on the grain boundaries under the microscope. The continuous distribution means that the tungsten-rich phase forms a continuous film or linear distribution and appears in a continuous state without disconnection under the microscope.
[0030] S3: Determine the optical microscopy inspection standard and electron microscopy inspection standard corresponding to the smelting method according to the smelting method of the steel pipe to be inspected.
[0031] Specifically, the smelting methods of the steel pipe to be inspected include: electroslag smelting and non-electroslag smelting. The tolerance of tungsten-rich phases varies significantly for different smelting methods. Therefore, in this embodiment, for steel pipes to be inspected with different smelting methods, different optical microscopy inspection standards and electron microscopy inspection standards are used for inspection to make a differential determination. It should be understood that step S3 can also be carried out before or between step S1 and step S2.
[0032] S4: Determine the preliminary inspection result of the steel pipe to be inspected according to the first metallographic information in the target inspection area and the optical microscopy inspection standard.
[0033] In this embodiment, determining the preliminary inspection result of the steel pipe to be inspected according to the first metallographic information in the target inspection area and the optical microscopy inspection standard specifically includes: Obtain the first metallographic information in the target inspection area. The first metallographic information includes the distribution pattern of tungsten-rich phases observed under an optical microscope. When the distribution pattern is a discrete distribution, it is determined that the preliminary inspection result of the steel pipe to be inspected is qualified. The discrete distribution means that several tungsten-rich phase particles are independently distributed. When the distribution pattern is a cluster distribution, the preliminary inspection result of the steel pipe to be inspected is determined according to the number of clusters, the length of the clusters and the first optical microscopy inspection standard. When the distribution pattern is a discontinuous grain boundary distribution or a continuous distribution, the preliminary inspection result of the steel pipe to be inspected is determined according to the distribution length and the second optical microscopy inspection standard.
[0034] Furthermore, the first optical microscopy inspection standard includes: the number of clusters ≤ X, and the length of the clusters ≤ Y µm. The second optical microscopy inspection standard includes: the distribution length ≤ Q µm. Among them, when the smelting method of the steel pipe to be inspected is electroslag smelting, X = 1, Y = 80, and Q = 40; when the smelting method of the steel pipe to be inspected is non-electroslag smelting, X = 3, Y = 150, and Q = 50.
[0035] Specifically, the cluster number refers to the number of clusters in a single optical microscope field of view at 100x magnification. When the tungsten-rich phase is distributed in clusters, the first metallographic information also includes the number and length of clusters within the target inspection area. When the tungsten-rich phase is distributed discontinuously along grain boundaries or continuously, the first metallographic information includes the distribution length of the tungsten-rich phase. Generally, tungsten-rich phase particles can be observed under a 500x optical microscope. However, in special cases, the tungsten-rich phase particles are extremely densely aggregated. Under a 500x optical microscope, only tungsten-rich phase aggregates can be observed in part or all of the tungsten-rich phase clusters, and the tungsten-rich phase particles cannot be clearly observed. Tungsten-rich phase particles can only be observed at a higher magnification. Considering the excessive aggregation of tungsten-rich phase particles, for this special case, the first optical microscope inspection standard also includes: aggregate length ≤ Zµm. When the steel pipe under inspection is smelted by electroslag remelting, Z=60; when the steel pipe under inspection is smelted by non-electroslag remelting, Z=120. Furthermore, if, under 500x optical microscopy, a tungsten-rich phase cluster consists of only one tungsten-rich phase aggregate, then the length of the aggregate is the cluster length; if, under 500x optical microscopy, a tungsten-rich phase cluster consists of one tungsten-rich phase aggregate and several tungsten-rich phase particles, then the cluster length is the total length of the cluster formed by the aggregate and the several tungsten-rich phase particles.
[0036] In one embodiment, the sample was observed under an optical microscope at 100x magnification, revealing a cluster of tungsten-rich phases in a certain field of view. Figure 2a As shown, the field of view of this optical mirror is determined as the target inspection area. Figure 2b for Figure 2a The optical microscope image of the central tungsten-rich cluster at 500x magnification shows that the cluster is formed by the aggregation of multiple tungsten-rich phase particles. There is one tungsten-rich phase cluster in the target inspection area, with a cluster length of 85.447µm. The smelting method of the sample is electroslag smelting. According to the first optical microscope inspection standard, the cluster length does not meet the standard, but the cluster number meets the standard. Therefore, the initial inspection result of the steel pipe is unqualified.
[0037] In another embodiment, the sample was observed under an optical microscope at 100x magnification, revealing a cluster of tungsten-rich phases in a certain field of view. Figure 2c As shown, the field of view of this optical mirror is determined as the target inspection area. Figure 2c for Figure 2d The optical microscope image of the central tungsten-rich cluster at 500x magnification shows that the cluster is formed by the aggregation of multiple tungsten-rich phase particles. There are two tungsten-rich phase clusters in the target inspection area, with cluster lengths of 44.419µm and 76.998µm, respectively. The smelting method of the sample is electroslag smelting. According to the first optical microscope inspection standard, the cluster length meets the standard, but the number of clusters does not meet the standard. Therefore, the initial inspection result of the steel pipe is unqualified.
[0038] S5: If the initial inspection results are satisfactory, the target inspection area shall be observed under an electron microscope.
[0039] Specifically, when the steel pipe to be inspected is smelted by electroslag remelting, according to the first optical microscopy inspection standard, if the tungsten-rich phase is discretely distributed, the initial inspection result of the steel pipe is qualified. If the distribution is clustered, the number of clusters in the target inspection area is ≤1, and the cluster length is ≤80µm, then the initial inspection result of the steel pipe is qualified. If the distribution is discontinuous along the grain boundary or continuous, according to the second optical microscopy inspection standard, the distribution length is ≤40µm, then the initial inspection result of the steel pipe is qualified.
[0040] When the steel pipe to be inspected is smelted using a non-electroslag smelting method, according to the first optical microscopy inspection standard, if the tungsten-rich phase is discretely distributed, the initial inspection result of the steel pipe is qualified. If the distribution is clustered, the number of clusters in the target inspection area is ≤3, and the cluster length is ≤150µm, then the initial inspection result of the steel pipe is qualified. If the distribution is discontinuous along the grain boundary or continuous, according to the second optical microscopy inspection standard, the distribution length is ≤50µm, then the initial inspection result of the steel pipe is qualified.
[0041] In this embodiment, the samples that passed the initial inspection were transferred to a scanning electron microscope (SEM) with back scattering electron (BSD) function for auxiliary observation. The magnification was 200x to 1000x, and the morphology of the tungsten-rich phase observed by the optical microscope was measured.
[0042] S6: Determine the inspection results of the steel pipe to be inspected based on the second metallographic information and electron microscopy inspection standards within the target inspection area.
[0043] Specifically, based on the second metallographic information and electron microscopy inspection standards within the target inspection area, the inspection results of the steel pipe to be inspected are determined, including: Second metallographic information is obtained within the target inspection area, including the distribution morphology of the tungsten-rich phase under electron microscopy. When the distribution morphology is discrete or clustered, the inspection result of the steel pipe is determined based on the tungsten-rich phase particle size and the first electron microscopy inspection standard. When the distribution morphology is discontinuous along grain boundaries or continuous, the inspection result of the steel pipe is determined based on the distribution length and the second electron microscopy inspection standard.
[0044] Specifically, when the tungsten-rich phase is distributed in a discrete or clustered manner, the second metallographic information also includes the particle size of the tungsten-rich phase. When the tungsten-rich phase is distributed discontinuously along grain boundaries or continuously, the second metallographic information includes the distribution length of the tungsten-rich phase.
[0045] In this embodiment, the first electron microscopy inspection standard includes: tungsten-rich phase particle size ≤ Fµm, and the proportion of tungsten-rich phase particles with a size of Eµm~Fµm ≤ 30%. The second electron microscopy inspection standard includes: distribution length ≤ Qµm. Specifically, when the steel pipe under inspection is smelted by electroslag remelting, E=2, F=3, and Q=40. When the steel pipe under inspection is smelted by non-electroslag remelting, E=2, F=5, and Q=50.
[0046] Specifically, when the steel pipe to be inspected is smelted by electroslag remelting, according to the first electron microscopy inspection standard, if the tungsten-rich phase is distributed discretely or in clusters, and the particle size of the tungsten-rich phase is ≤3µm, and the proportion of tungsten-rich phase particles with a size of 2µm~3µm is ≤30%, then the inspection result of the steel pipe to be inspected is qualified. If the distribution is discontinuous along the grain boundaries or continuous, according to the second electron microscopy inspection standard, if the distribution length is ≤40µm, then the inspection result of the steel pipe to be inspected is qualified.
[0047] When the steel pipe to be inspected is smelted using a non-electroslag smelting method, according to the first electron microscopy inspection standard, if the tungsten-rich phase is distributed discretely or in clusters, and the particle size of the tungsten-rich phase is ≤5µm, and the proportion of tungsten-rich phase particles with a size of 2µm~5µm is ≤30%, then the inspection result of the steel pipe to be inspected is qualified. If the distribution pattern is discontinuous along the grain boundaries or continuous, according to the second electron microscopy inspection standard, if the distribution length is ≤50µm, then the inspection result of the steel pipe to be inspected is qualified.
[0048] In one embodiment, the linear cluster-like tungsten-rich phase observed under an optical microscope is observed using a scanning electron microscope with backscattered electron function. The scanning electron microscope image obtained at 500x magnification is shown below. Figure 3a and Figure 3b As shown, Figure 3a and Figure 3b In the figure, EHT represents the accelerating voltage, WD represents the working distance, Mag represents the magnification, and Signal A represents the detector type. The bright white area in the figure represents tungsten-rich phase particles. The smelting method of the sample to be tested is electroslag smelting. According to the first electron microscopy inspection standard, the proportion of tungsten-rich phase particles with a size of 2µm to 3µm in the linear cluster tungsten-rich phase is 5%, and the largest tungsten-rich phase particle size is 4.1µm. The inspection result of the steel pipe to be tested is unqualified.
[0049] In this embodiment, if the initial inspection or test result of any sample of the steel pipe to be inspected is unqualified, the steel pipe to be inspected is preliminarily determined to be unqualified. In this embodiment, the steel pipe to be inspected is double-sampled for re-inspection. Specifically, double the number of samples are taken from the original sampling location of the steel pipe to be inspected, and the test method provided in this embodiment is used for testing. If all the re-inspected samples are qualified, the steel pipe to be inspected is determined to be qualified. For the uninspected steel pipes in the same batch as the steel pipe to be inspected, one sample is taken for testing. Steel pipes with unqualified test results are not re-inspected and are directly considered unqualified. If the initial inspection and test results of all samples of the steel pipe to be inspected are qualified, the steel pipe to be inspected is determined to be qualified, and thus the batch of the steel pipe to be inspected is determined to be qualified.
[0050] This embodiment provides an inspection method for G115 martensitic heat-resistant steel pipes. The steel pipes under inspection are subjected to tungsten-rich phase inspection using optical microscopy and electron microscopy. Targeted judgment criteria are formulated for different smelting methods of the steel pipes under inspection to achieve targeted and systematic judgment of the steel pipes' qualification, avoid potential failure risks caused by abnormal tungsten-rich phases, effectively detect defective steel pipes, and improve inspection accuracy.
[0051] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.
[0052] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.
Claims
1. A test method for G115 martensitic heat-resistant steel pipes, characterized in that, Includes the following steps: Prepare the sample of the steel pipe to be inspected; The sample to be tested is observed under a light microscope to determine the target testing area, which is the region where the tungsten-rich phase is located. Based on the smelting method of the steel pipe to be inspected, determine the optical microscopy inspection standard and electron microscopy inspection standard corresponding to the smelting method; Based on the first metallographic information within the target inspection area and the optical microscopy inspection standard, the preliminary inspection result of the steel pipe to be inspected is determined; If the initial inspection results are satisfactory, the target inspection area will be observed under an electron microscope. The inspection result of the steel pipe to be inspected is determined based on the second metallographic information within the target inspection area and the electron microscopy inspection standard.
2. The testing method according to claim 1, characterized in that, The smelting methods include: electroslag smelting and non-electroslag smelting.
3. The testing method according to claim 2, characterized in that, The preliminary inspection result of the steel pipe to be inspected is determined based on the first metallographic information within the target inspection area and the optical microscopy inspection standard, specifically including: Obtain first metallographic information within the target inspection area, the first metallographic information including the distribution morphology of the tungsten-rich phase under light microscopy observation; When the distribution pattern is discrete, the initial inspection result of the steel pipe to be inspected is determined to be qualified. The discrete distribution refers to the independent distribution of several tungsten-rich phase particles. When the distribution pattern is a cluster distribution, the initial inspection result of the steel pipe to be inspected is determined according to the number of clusters, the cluster length, and the first optical microscope inspection standard. When the distribution pattern is discontinuous along the grain boundary or continuous, the initial inspection result of the steel pipe to be inspected is determined according to the distribution length and the second optical microscope inspection standard.
4. The testing method according to claim 3, characterized in that, The first optical microscopy inspection criteria include: the number of clusters ≤ X, and the cluster length ≤ Yµm; The second optical microscopy inspection standard includes: the distribution length ≤ Qµm; Wherein, when the smelting method of the steel pipe to be inspected is electroslag smelting, X=1, Y=80, Q=40; When the steel pipe to be inspected is smelted by non-electroslag smelting, X=3, Y=150, Q=50.
5. The testing method according to claim 2, characterized in that, The step of determining the inspection result of the steel pipe to be inspected based on the second metallographic information within the target inspection area and the electron microscopy inspection standards specifically includes: Obtain second metallographic information within the target inspection area, the second metallographic information including the distribution morphology of the tungsten-rich phase under electron microscopy observation; When the distribution pattern is discrete or clustered, the inspection result of the steel pipe to be inspected is determined according to the size of the tungsten-rich phase particles and the first electron microscopy inspection standard. When the distribution pattern is discontinuous along the grain boundary or continuous, the inspection result of the steel pipe to be inspected is determined according to the distribution length and the second electron microscopy inspection standard.
6. The testing method according to claim 5, characterized in that, The first electron microscopy inspection criteria include: the size of the tungsten-rich phase particles is ≤ Fµm, and the proportion of tungsten-rich phase particles with a size of Eµm~Fµm is ≤30%; The second electron microscopy inspection standard includes: the distribution length ≤ Qµm; Wherein, when the smelting method of the steel pipe to be inspected is electroslag smelting, E=2, F=3, Q=40; When the steel pipe to be inspected is smelted by non-electroslag smelting, E=2, F=5, Q=50.
7. The test method according to claim 1, characterized in that, The preparation of the test sample for the steel pipe to be tested includes: Take at least two samples from the steel pipe to be inspected; The inspection surface of the sample is pretreated to obtain the inspection sample of the steel pipe to be inspected.
8. The testing method according to claim 7, characterized in that, The test surface of the sample is a plane parallel to the radial surface of the steel pipe to be tested.
9. The testing method according to claim 7, characterized in that, One of the at least two samples is taken from the inner wall of one end of the steel pipe to be tested.
10. The testing method according to claim 7, characterized in that, The pretreatment includes sequential grinding, polishing, and etching.