A nondestructive testing method for second-phase cluster particles in reactor pressure vessel steel
The non-destructive analysis of reactor pressure vessel steel through internal consumption detection method solves the problem that nanocluster defects cannot be accurately detected in the prior art, achieves a lossless and fast detection effect, and obtains qualitative and quantitative information on the microscopic change process of the material.
Patent Information
- Application Number
- CN202210721732.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-24
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2042-06-24
AI Technical Summary
It is difficult for the prior art to accurately and comprehensively detect and characterize nanocluster defects in reactor pressure vessel steel, especially in the early stage of formation. Common methods have problems such as high destructiveness, small areas, large errors or many assumptions.
The internal consumption detection method is adopted, and the temperature-internal consumption curve is drawn after different heat treatments on RPV steel, and the nanocluster precipitation phase content is analyzed by comparing the Snoek-type internal consumption peak and grain boundary relaxation internal consumption peak to achieve non-destructive detection.
Non-destructive testing is realized, the operation is simple, fast and reliable, and can detect the diffusion movement and interaction of defects with high sensitivity, and obtain qualitative and quantitative micro-change information.
Smart Images
Figure CN114965701B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of nondestructive testing of metal materials, and particularly to a method for nondestructively testing second-phase cluster particles in reactor pressure vessel steel. Background Art
[0002] In recent years, with the continuous increase in the number of annual haze days and the increasingly deteriorating climatic conditions in China, nuclear energy has received extensive attention. A reactor pressure vessel (RPV) is an irreplaceable core key component in the primary loop of a nuclear reactor. It plays important roles such as supporting the reactor core, containing radioactive substances and coolant, and maintaining the operating pressure inside the reactor. The service life of the RPV determines the safety, life, and economic benefits of the entire nuclear power plant.
[0003] However, under conditions of high temperature, high pressure, fluid erosion, corrosion, and high-energy neutron irradiation, the tendency of the RPV material to undergo brittle fracture increases. The precipitation of second-phase clusters or particles is the main factor causing hardening and embrittlement of the RPV material. Regularly monitoring and evaluating the evolution behavior of the microstructure and defects in the RPV steel and delaying the process of embrittlement are outstanding problems that must be solved in the field of nuclear materials research. How to detect or observe the solute atom nanoclusters induced by irradiation in materials is very important in the field of radiation damage research.
[0004] Given that the size and degree of change of these nanoclusters are extremely small, especially in their early formation stage, general experimental means are difficult to accurately and comprehensively detect and characterize these defects. Currently, the commonly used experimental methods at home and abroad include: atom probe tomography (APT), small-angle neutron scattering (SANS), transmission electron microscopy (TEM), positron annihilation spectroscopy (PAS), etc. These methods each have their own unique advantages in the research on the mechanism of radiation defects.
[0005] The APT technology can obtain the composition, size, and cluster density of solute atom nanoclusters in the matrix, etc. However, it is a destructive testing method, with high requirements for sample preparation and a small analysis area; SANS can obtain the average size distribution of nanoclusters above 0.5 nm, but there are relatively large analysis errors and it needs to be combined with other methods for analysis and verification; while the main feature of the PAS method is that it can estimate the defect concentration related to vacancies, vacancy clusters, etc. However, the analysis of the PAS results requires many theoretical assumptions and has a certain degree of uncertainty.
[0006] Internal friction is an important experimental technique for studying the defects and mechanical properties of solids. It can highly sensitively detect the existence of point defects, dislocations, interfaces and other defects in solids, as well as the diffusion motion of various defects and the interaction between defects, so as to obtain qualitative and quantitative information on various microscopic change processes in materials. As a non-destructive testing method, internal friction has the advantages of simple sample preparation, low requirements for the sample surface, easy operation and large testing area, and can analyze the existence and motion of defects in the whole sample. Summary of the Invention
[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a non-destructive testing method for the second-phase cluster particles in reactor pressure vessel steel, so as to solve the technical problem that the existing testing techniques cannot accurately and comprehensively detect and characterize these nano-cluster defects.
[0008] The present invention realizes the above purpose through the following technical solutions:
[0009] A non-destructive testing method for the second-phase cluster particles in reactor pressure vessel steel, comprising:
[0010] Step 1: Subject the RPV steel to different heat treatments under a protective atmosphere to obtain RPV steel treated samples with different contents of nano-cluster precipitation phases, and retain the RPV steel without heat treatment as the original sample for comparative reference;
[0011] Step 2: Cut the treated samples and the original sample in Step 1 into a specified shape, and grind off the cutting marks to make the surface shiny;
[0012] Step 3: Conduct internal friction tests on the cut treated samples and the original sample. The test data takes temperature as the X-axis and the internal friction value as the Y-axis, and plot the temperature-internal friction curve to obtain the Snoek-type internal friction peak and / or the grain boundary relaxation internal friction peak of different samples;
[0013] Step 4: Compare and analyze the temperature-internal friction curves of the RPV steel treated samples with different contents of nano-cluster precipitation phases and the original sample, and determine the content of the nano-cluster precipitation phase of the RPV steel through the Snoek-type internal friction peak and / or the grain boundary relaxation internal friction peak.
[0014] Further improvement lies in that the main components of the RPV steel are Fe-(0-2) wt.% Mn-(0-2) wt.% Ni-(0-1) wt.% Si-(0-1) wt.% Cu.
[0015] Further improvement lies in that in Step 1, the protective atmosphere refers to argon.
[0016] Further improvement lies in that, in step one, the heat treatment is carried out in a tube furnace at 300 - 700 °C for aging for 0 - 500 h respectively to induce the precipitation of nano-cluster particles in the RPV steel, and the cooling method of the treated sample obtained by heat treatment is furnace cooling or quenching treatment.
[0017] Further improvement lies in that the specific operation of step two is as follows: Cut the treated sample and the original sample in step one into strips of about 2×1×30 mm by wire cutting, and grind off the wire cutting marks on sandpaper with 240 - 2000 meshes until the surface is bright.
[0018] Further improvement lies in that, in step three, the internal friction test is carried out by an internal friction instrument. Under the free decay or forced vibration mode, the temperature is raised from -50 °C to 300 °C at a heating rate of 2 °C / min or from 400 °C to 750 °C, the heating rate is 1 - 3 °C / min, and the test amplitude is (1 - 5)×10 -5 , and the test frequencies are 0.1 - 10 Hz respectively.
[0019] Further improvement lies in that, in step four, when determining the content of the nano-cluster precipitation phase: The second-phase precipitation particles pin the grain boundaries, resulting in a decrease in the internal friction peak of grain boundary relaxation. Therefore, the lower the peak height of the grain boundary relaxation internal friction peak, the more the content of the nano-cluster precipitation phase; The peak height of the Snoek-type internal friction peak is proportional to the interstitial carbon content, and the peak shape can reflect the interaction between interstitial carbon atoms and solute atoms.
[0020] The beneficial effects of the present invention are as follows:
[0021] ① Non-destructive testing: It does not require destructive testing on the sample surface and belongs to the category of non-destructive testing.
[0022] ② Simple operation, easy preparation of specimens, and simple, rapid and reliable testing.
[0023] ③ It can detect the diffusion movement of various defects and the interaction between defects in solids with high sensitivity, and obtain qualitative and quantitative information on various microscopic change processes in materials. Description of the Drawings
[0024] Figure 1 is the temperature-internal friction curve at different frequencies in the forced vibration mode with a heating rate of 3 °C / min for the RPV steel Fe-1.35 wt.% Mn-0.74 wt.% Ni-0.19 wt.% Si material based on Example 1 of the present invention;
[0025] Figure 2 is the temperature-internal friction curve at different frequencies in the forced vibration mode with a heating rate of 3 °C / min for the RPV steel Fe-1.35 wt.% Mn-0.74 wt.% Ni-0.19 wt.% Si-0.1 wt.% Cu material based on Example 2 of the present invention;
[0026] Figure 3 It is the temperature - internal friction curve of the RPV steel Fe - 1.35wt.% Mn - 0.74wt.% Ni - 0.19wt.% Si material at a heating rate of 2°C / min in the free decay mode. Detailed implementation manners
[0027] The following further describes the present application in detail with reference to the accompanying drawings. It is necessary to point out here that the following detailed implementation manners are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. Those skilled in the art can make some non - essential improvements and adjustments to the present application according to the above application content.
[0028] Example 1
[0029] This example provides a non - destructive testing method for determining the precipitation of the second phase in RPV steel through the grain - boundary relaxation internal - friction peak, as Figure 1 shown, including the following steps:
[0030] Step 1: Put the RPV steel Fe - 1.35wt.% Mn - 0.74wt.% Ni - 0.19wt.% Si material into a tubular furnace protected by an argon atmosphere, keep it at 600°C for 10 min, 30 min, 1 h, 20 h, and 100 h respectively, and cool it to room temperature with the tubular furnace to obtain RPV steel treated samples with different contents of nano - cluster precipitation phases, and retain an unaged sample as the original sample for comparison.
[0031] Step 2: Wire - cut the treated samples and the original sample in Step 1 into strips of about 2×1×30 cm, grind off the wire - cutting marks on sandpaper with 240 - 2000 meshes until the surface is shiny.
[0032] Step 3: Install the cut - after treated samples and the original sample on the internal - friction instrument device, heat from room temperature to 800°C at a rate of 3°C / min in the forced vibration mode, test the amplitude as 2×10 -5 , and measure the temperature - internal friction curves at test frequencies of 0.5, 1, 2, and 4 Hz respectively. A grain - boundary relaxation internal - friction peak P1 appears at 600 - 700°C, and the peak temperature moves to a higher temperature as the frequency increases. Determine that the P1 peak is a grain - boundary relaxation internal - friction peak according to the activation energy. The longer the aging time at 600°C, the lower the peak height of the grain - boundary relaxation internal - friction peak, indicating that more second phases precipitate at the grain boundaries in the RPV simulated steel.
[0033] Example 2
[0034] This example provides a non - destructive testing method for determining the precipitation of the second phase in RPV steel through the grain - boundary relaxation internal - friction peak, asFigure 2 As shown in the figure, it includes the following steps:
[0035] Step 1: Put the RPV steel Fe-1.35wt.%Mn-0.74wt.%Ni-0.19wt.%Si-0.1wt.%Cu material into a tube furnace protected by an argon atmosphere, and keep it at 600 °C for 10 min, 30 min, 1 h, 20 h, and 200 h respectively. Then cool it to room temperature with the tube furnace to obtain RPV steel treated samples with different contents of nano-cluster precipitation phases, and keep an untreated sample as the original sample for comparison.
[0036] Step 2: Cut the treated samples and the original sample in Step 1 into strips of about 2×1×30 cm with wire cutting, and grind off the wire cutting marks on sandpaper with a grit size of 240-2000 until the surface is bright.
[0037] Step 3: Install the cut treated samples and the original sample on the internal friction instrument device, and heat them from room temperature to 800 °C at a rate of 3 °C / min in the forced vibration mode, with a test amplitude of 2×10 -5 , and measure the temperature-internal friction curves at test frequencies of 0.5, 1, 2, and 4 Hz respectively. A relaxation-type internal friction peak P1 appears at 600-700 °C, and the peak temperature moves to a higher temperature as the frequency increases. According to the activation energy, it is determined that the P1 peak is the grain boundary relaxation internal friction peak. The longer the aging time at 600 °C, the lower the peak height of the grain boundary relaxation internal friction peak, indicating that more second phases precipitate at the grain boundaries in the RPV simulated steel.
[0038] Example 3
[0039] This example provides a non-destructive testing method for determining the precipitation of the second phase in RPV steel through the Snoek-type internal friction peak, as Figure 3 shown in the figure, including the following steps:
[0040] Step 1: Put the RPV steel Fe-1.35wt.%Mn-0.74wt.%Ni-0.19wt.%Si material into a tube furnace protected by an argon atmosphere, and keep it at 600 °C for 20 min, 1 h, 2 h, 5 h, 10 h, 20 h, and 200 h respectively. Then cool it to room temperature by quenching treatment to obtain RPV steel treated samples with different contents of nano-cluster precipitation phases, and keep an untreated sample as the original sample for comparison.
[0041] Step 2: Cut the treated samples and the original sample in Step 1 into strips of about 2×1×30 cm with wire cutting, and grind off the wire cutting marks on sandpaper with a grit size of 240-2000 until the surface is bright.
[0042] Step 3: Install the processed sample and the original sample after cutting onto the internal friction apparatus, and heat from -50°C to 400°C at a rate of 2°C / min in the free decay mode, with a test amplitude of 2×10 -5 Measure the temperature-internal friction curve. A relaxation-type internal friction peak P1 and P2 appear at 0 - 150°C, and the peak temperature shifts to a higher temperature as the frequency increases. It is determined that the P1 and P2 peaks are Snoek-type internal friction peaks. The longer the aging time at 600°C, the lower the peak height of the Snoek-type internal friction peak, indicating that as the aging time increases, more interstitial carbon atoms in the RPV simulated steel co-precipitate with other solute atoms.
[0043] The Snoek-type peak includes peak P1 and peak P2, which respectively originate from the jumps of carbon atoms in the Fe-C-Fe lattice and the Fe-C-Me (Me is the substitutional atom Mn, Ni, Si) lattice. During short-term aging of the sample (i.e., aging for 20 min, 1 h, and 2 h), due to the attraction of the substitutional atom, the interstitial carbon atoms jump into the Fe-C-Me lattice, so the carbon atom content in the Fe-C-Me lattice increases, causing peak P2 to increase. When the aging time is longer (5 h, 10 h, 20 h, and 200 h), the interstitial carbon atoms and the substitutional atoms co-segregate to the grain boundary, resulting in a decrease in the interstitial carbon atom content in the solid solution and an increase in peak P2. During short-term aging, only the carbon atoms jump in the solid solution and no precipitation occurs. As the aging time increases, carbon atom precipitation occurs, resulting in a decrease in the interstitial carbon atom content, ultimately leading to a decrease in the peak heights of both P1 and P2.
[0044] Compared with the prior art, the non-destructive testing method of detecting the precipitation of the second-phase cluster particles in the reactor pressure vessel steel by internal friction described in the present invention overcomes the difficulties of other testing means such as difficult operation, difficult sample preparation, smaller analysis area, and smaller precipitated phases that are difficult to detect. It has a wide range of application fields, especially playing a greater role in the testing means where the second-phase particles in the steel are smaller and difficult to detect.
[0045] The above-described embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.
Claims
1. A non-destructive testing method for second-phase cluster particles in reactor pressure vessel steel, characterized in that Including: Step 1: Subject the RPV steel to different heat treatments under a protective atmosphere to obtain RPV steel treated samples with different contents of nano-cluster precipitation phases, and retain the untreated RPV steel as the original sample for comparative reference; the main components of the RPV steel are Fe-(0-2) wt.% Mn-(0-2) wt.% Ni-(0-1) wt.% Si-(0-1) wt.% Cu; Step 2: Cut the treated samples and the original sample in Step 1 into a specified shape and grind off the cutting marks to make the surface shiny; Step 3: Conduct internal friction tests on the cut treated samples and the original sample. Plot the temperature-internal friction curve with the test data having temperature as the X-axis and the internal friction value as the Y-value to obtain the Snoek-type internal friction peak and the grain boundary relaxation internal friction peak of different samples; Step 4: Compare and analyze the temperature-internal friction curves of the RPV steel treated samples with different contents of nano-cluster precipitation phases and the original sample, and determine the content of the nano-cluster precipitation phase in the RPV steel through the Snoek-type internal friction peak and the grain boundary relaxation internal friction peak; when determining the content of the nano-cluster precipitation phase: the lower the peak height of the grain boundary relaxation internal friction peak, the more the content of the nano-cluster precipitation phase; the peak height of the snoek-type internal friction peak is proportional to the interstitial carbon content.
2. The non-destructive testing method for the second-phase cluster particles in the reactor pressure vessel steel according to claim 1, characterized in that, In Step 1, the protective atmosphere refers to argon.
3. The non-destructive testing method for the second-phase cluster particles in the reactor pressure vessel steel according to claim 1, characterized in that In Step 1, the heat treatment is aging at 300-700 °C for 0-500 h in a tube furnace to induce the precipitation of nano-cluster particles in the RPV steel. The cooling method of the treated samples obtained by heat treatment is furnace cooling or quenching treatment.
4. The non-destructive testing method for the second-phase cluster particles in the reactor pressure vessel steel according to claim 1, characterized in that The specific operation of Step 2 is: Cut the treated samples and the original sample in Step 1 into strips of 2×1×30 mm with wire cutting and grind off the wire cutting marks on sandpaper with a grit size of 240-2000 until the surface is shiny.
5. The non-destructive testing method for the second-phase cluster particles in the reactor pressure vessel steel according to claim 1, characterized in that, In Step 3, the internal friction test is performed using an internal friction tester. The temperature is increased from -50°C to 300°C at a rate of 2°C / min or from 400°C to 750°C at a rate of 1 - 3°C / min in the free decay or forced vibration mode, and the test amplitude is (1 - 5)×10 -5 , and the test frequencies are 0.1 - 10 Hz respectively.