Method for measuring in-situ internal friction of MC carbide solid solution and precipitation temperature

Abstract

The present application belongs to the technical field of metal materials, and particularly relates to a method for in-situ measuring MC carbide solid solution and precipitation temperature by internal friction. The present application uses pure iron and pure chromium to prepare Fe-Cr based alloy samples, processes the samples into internal friction samples after solid solution and rolling; in a vacuum environment, the samples are heated to a preset target temperature covering the expected solid solution characteristic temperature range of MC carbide at a constant rate and are kept at the temperature, then are cooled at the same rate, the internal friction value and modulus are continuously measured, and a first and second in-situ internal friction temperature spectrum is drawn; the frequency dispersion characteristics of grain boundary relaxation peak, the internal friction value mutation and the modulus change in the two temperature spectra are compared to determine the solid solution temperature and precipitation temperature of MC carbide. The method has high sensitivity and simple operation, and is suitable for in-situ characterization of grain boundary precipitates in low carbon content Fe-Cr based alloys.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials technology, and in particular relates to a method for in-situ measurement of the solid solution and precipitation temperatures of MC-type carbides with internal friction. Background Technology

[0002] Carbon (C) is one of the most important alloying elements in steel. During the heat treatment of low-alloy steel, high-strength steel, and heat-resistant steel, MC-type carbides are often formed, where M is mostly composed of metallic elements such as Cr, Mo, and Nb. Under different heat treatment regimes, the degree of solid solution, precipitation temperature range, and growth behavior of MC-type carbides vary significantly, which has a crucial impact on the toughness and damping level of the final microstructure.

[0003] Existing methods for studying the dissolution and precipitation behavior of MC-type carbides and other precipitated phases include differential scanning calorimetry (DSC), thermal expansion method, resistivity method, and traditional internal friction method based on the SKK peak. Among these, DSC can provide a relatively intuitive and accurate range of dissolution and precipitation temperatures for the corresponding precipitated phases, to some extent compensating for the shortcomings of traditional physicochemical phase analysis and electron microscopy, which "can only observe existing precipitated phases and cannot directly provide temperatures." However, this method reflects the overall endothermic and exothermic behavior of the material, and the obtained peak temperatures are highly dependent on the heating and cooling rates and sample mass. The dissolution and precipitation temperatures measured under different experimental conditions exhibit non-negligible deviations, and the sensitivity is limited for precipitated phases with low volume fractions and weak thermal effects (such as small amounts of fine MC).

[0004] Thermal expansion measures overall volume change and is sensitive to major phase transformation processes such as ferrite / austenite phase transformation. However, for MC carbides with low volume fraction and small size, the volume change caused by dissolution or precipitation is minimal and easily overwhelmed by the major phase transformation signal, making it difficult to achieve high-precision identification of the dissolution and precipitation temperatures of MC carbides.

[0005] The resistivity method can clearly show the dissolution range of Nb(C,N) carbonitrides by comparing resistivity at multiple temperature points. However, this method relies on multiple samples and stepwise solution heat treatment, and cannot track the dissolution behavior of precipitates in situ during actual continuous heating. The resistivity signal is also affected by grain size, dislocation density, other precipitates, and phase transformations.

[0006] Traditional internal friction methods based on the SKK peak can accurately provide the solution temperature range and dissolution / precipitation amount of Nb(C,N) or Fe3C, which is valuable for designing heat treatment regimes for low-carbon microalloyed steels. However, this method only tests Nb(C,N) or Fe3C in C-Mn-based low-carbon microalloyed steels and does not consider the special thermal stability and interfacial characteristics of MC-type carbides in high-Cr-content α-Fe-Cr based alloys, so it cannot be directly applied to Fe-Cr based systems. Furthermore, this method uses an indirect approach of "high-temperature pretreatment + low-temperature internal friction measurement," meaning the high-temperature dissolution and precipitation processes are not recorded in situ during the internal friction test, making it difficult to reflect the continuity of precipitated phase evolution under the actual heating path.

[0007] In summary, while existing methods have made significant progress in determining the dissolution / precipitation temperatures of Nb(C,N) and Fe3C precipitates in low-carbon microalloyed steels, they generally suffer from the following common problems:

[0008] 1. Most methods measure the overall thermal effect or volumetric and electrical response, and have limited sensitivity for MC-type carbides with low volume fraction and weak thermal and volumetric effects.

[0009] 2. Most existing methods rely on multi-sample, stepwise high-temperature pretreatment, which is an indirect characterization method. It is difficult to continuously and in situ track the evolution of the precipitated phase in the actual heating path on a single sample.

[0010] 3. Existing internal friction methods focus on Nb(C,N) and Fe3C, and cannot measure the dissolution and precipitation process of MC-type carbides in situ during the test. There is a lack of targeted in-situ measurement methods for MC-type carbide systems in Fe-Cr based alloys.

[0011] 4. Existing methods require a sufficiently high carbon content in the material (≥0.1 wt.%) for measurement. Summary of the Invention

[0012] To overcome the shortcomings of the prior art, this invention provides a method for in-situ measurement of the solid solution and precipitation temperatures of MC-type carbides. This invention has advantages such as high sensitivity, simple operation, and obvious phenomena.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A method for in-situ measurement of the solid solution and precipitation temperatures of MC-type carbides with internal friction, the specific steps of which are as follows:

[0015] S1. Alloy samples were prepared by electric arc melting of pure iron and pure chromium, and then dissolved at 1200-1400℃ for 2-4 hours under argon atmosphere before rolling to obtain Fe-Cr based alloy samples.

[0016] S2. Cut and grind the Fe-Cr based alloy sample according to the internal friction sample size to obtain the internal friction test sample, install it on the internal friction measuring instrument, and then heat the internal friction test sample from room temperature to the preset target temperature covering the expected solid solution characteristic temperature range of MC type carbides at a constant heating rate, hold it at the temperature, and then cool it to room temperature. At the same time, measure the internal friction value and modulus of the internal friction test sample.

[0017] S3, with temperature as the X-axis, internal friction value Q -1 Using the modulus as the Y-axis, plot the internal friction temperature spectrum 1 for the heating and cooling process, and complete one in-situ test;

[0018] S4. Repeat steps S2 and S3 to perform in-situ secondary testing to obtain the internal friction temperature spectrum 2.

[0019] S5. Compare internal friction temperature spectrum 1 and internal friction temperature spectrum 2. In internal friction temperature spectrum 2, the frequency dispersion characteristics of the grain boundary relaxation peaks weaken or disappear during heating, accompanied by an internal friction value Q. -1 The characteristic temperatures of the sudden increase and sudden decrease in modulus are the solid solution temperatures of MC-type carbides; there is a significant thermal hysteresis behavior during cooling, and the internal friction value Q is [missing information]. -1 The temperature at which the modulus suddenly drops and then rebounds is the precipitation temperature of MC-type carbides.

[0020] Preferably, the carbon content of the Fe-Cr based alloy sample is ≥0.003 wt.%.

[0021] Preferably, the chemical composition of the Fe-Cr based alloy sample includes 15-30 wt.% Cr, with the balance being Fe.

[0022] Preferably, in step S2, a forced vibration mode is used to measure the internal friction value and modulus of the internal friction test sample at a test frequency of 0.1 to 10 Hz. The test frequencies are preferably 0.5 Hz, 1 Hz, 2 Hz and 4 Hz.

[0023] Preferably, in step S2, the constant heating rate is 1–5 °C / min, more preferably 3 °C / min; the preset target temperature is determined from the iron-chromium alloy phase diagram (e.g., Figure 11 The temperature was obtained as shown, with a preset target temperature of 800-900℃, and kept at that temperature for 10 minutes, then cooled to room temperature at the same rate.

[0024] Preferably, in step S2, the amplitude of the forced vibration mode is set to 1×10. -6 ~1×10 -4 Further preferred is 2×10 -5 .

[0025] Preferably, in step S2, the dimensions of the internal friction test sample are 20–40 mm in length, 1–3 mm in width, and 0.5–2 mm in thickness; more preferably, it is 30 × 2 × 1.5 mm. 3 .

[0026] Preferably, step S2 is performed under a vacuum or protective atmosphere.

[0027] Preferably, in step S2, the cut sample is polished to 1200-1500 grit with sandpaper to ensure a smooth surface on the alloy sample and reduce scratches.

[0028] Preferably, in step S2, after the internal friction test sample is processed, it is ultrasonically cleaned to remove residual oil from wire cutting.

[0029] The advantages of this invention are:

[0030] (1) This invention performs multiple in-situ tests on the sample, determines the precipitation of MC-type carbides at the grain boundaries based on the morphological changes of the grain boundary peaks, and judges the solid solution temperature and precipitation temperature based on the internal friction peaks at higher temperatures. The MC-type precipitates in this invention are small in volume, the overall carbon content of the alloy is low, and the dissolution and precipitation temperatures of MC-type carbides can be detected in situ. The dissolution and precipitation process of MC-type carbides with temperature changes can also be observed, and the phenomena are obvious. Moreover, the whole method has high sensitivity and simple operation steps.

[0031] (2) This invention proposes to measure the solid solution and precipitation temperatures of precipitates at grain boundaries by in-situ internal friction test. The internal friction temperature spectrum is extremely sensitive to changes in the microstructure of the material and can non-destructively detect changes in the internal condition of the material. Each internal friction peak in the internal friction temperature spectrum corresponds to a unique change inside the material.

[0032] (3) This invention selects pure iron and pure chromium as raw materials, with only Cr containing a very small amount of C. To prevent carbon contamination, a vacuum arc melting furnace is used to prepare the alloy, and the alloy is heat-treated under an argon atmosphere. The carbides mentioned in this invention are grain boundary precipitates in Fe-Cr alloys. The grain boundary relaxation peak (internal friction peak) is very sensitive to the mobility of the material's grain boundaries and is affected by grain boundary precipitation and solute atoms. When precipitates are present on the grain boundaries, they inhibit the relevant relaxation process of the grain boundaries, and the grain boundary relaxation (internal friction) peak disappears as a result. When the temperature is further increased, the precipitates dissolve, and the corresponding dissolution and reprecipitation process can be observed near the grain boundary peak. Attached Figure Description

[0033] Figure 1 This is the internal friction temperature spectrum 1 obtained from an in-situ test in Embodiment 1 of the present invention.

[0034] Figure 2This is the internal friction temperature spectrum 2 obtained from the in-situ secondary test in Embodiment 1 of the present invention.

[0035] Figure 3 This is the internal friction temperature spectrum of the alloy sample in Comparative Example 1 of the present invention at 800℃.

[0036] Figure 4 This is the internal friction temperature spectrum of the alloy sample in Comparative Example 1 of the present invention at 900℃.

[0037] Figure 5 This is the internal friction temperature spectrum of the alloy sample in Comparative Example 1 of the present invention at 1000℃.

[0038] Figure 6 This is the internal friction temperature spectrum of the alloy sample in Comparative Example 2 of the present invention at 800℃.

[0039] Figure 7 This is a SEM image of the alloy sample in Comparative Example 1 of the present invention at 800℃.

[0040] Figure 8 This is a SEM image of the alloy sample in Comparative Example 1 of the present invention at 900℃.

[0041] Figure 9 This is a SEM image of the alloy sample in Comparative Example 1 of the present invention at 1000℃.

[0042] Figure 10 This is a SEM image of the alloy sample in Comparative Example 2 of the present invention at 800℃.

[0043] Figure 11 This is the phase diagram of the iron-chromium alloy of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0045] Example 1

[0046] A method for in-situ measurement of the solid solution and precipitation temperatures of MC-type carbides with internal friction includes the following steps:

[0047] S1. An alloy sample with a nominal composition of Fe-15wt.%Cr (i.e., including 15wt.%Cr and the balance being Fe) was prepared by electric arc melting of pure iron and pure chromium. The sample was then solution-treated at 1400℃ for 2 hours under an argon atmosphere and rolled to obtain an Fe-Cr based alloy sample with a carbon content of 0.003wt.%. This ensures that the alloy sample has a more uniform composition. The rolling deformation can refine the grains, increase the dislocation density, and improve the mechanical properties of the alloy.

[0048] S2. Use an electrical discharge wire cutting machine to cut the rolled Fe-Cr based alloy sample into 1.5×2×30mm pieces. 3 The internal friction test sample was then polished to 1200 mesh and then placed in a heavy oil stain cleaner for ultrasonic cleaning.

[0049] S3. Fix both ends of the internal friction test sample onto the clamps of the multifunctional inverted torsion pendulum internal friction instrument. To avoid high-temperature oxidation of the alloy sample, maintain a vacuum state in the laboratory. Then heat from room temperature to 800℃ at a rate of 3℃ / min and hold for 10 minutes; then cool to room temperature at the same rate; the test amplitude is kept constant at 2×10. -5 The frequencies were 0.5Hz, 1Hz, 2Hz and 4Hz, and the internal friction value and modulus of the internal friction test sample were measured.

[0050] S4. Plot the internal friction temperature spectrum 1 for the heating and cooling processes, with temperature as the X-axis and internal friction value and modulus as the Y-axis, as shown in Figure 1. Figure 1 As shown, one in-situ test was completed;

[0051] S5. Repeat steps S3 and S4 to perform a second in-situ test, obtaining the internal friction temperature spectrum 2, as shown below. Figure 2 As shown;

[0052] S6. Compare internal friction temperature spectrum 1 and internal friction temperature spectrum 2. The characteristic temperature at which the frequency dispersion of the grain boundary relaxation peak weakens or disappears when the temperature rises, accompanied by a sudden increase in internal friction value and a sudden decrease in modulus, is the solid solution temperature of MC-type carbides. The characteristic temperature at which thermal hysteresis occurs when the temperature drops, and the characteristic temperature at which internal friction value drops suddenly and modulus recovers, is the precipitation temperature of MC-type carbides.

[0053] Example 2

[0054] A method for in-situ measurement of the solid solution and precipitation temperatures of MC-type carbides with internal friction includes the following steps:

[0055] S1. An alloy sample with a nominal composition of Fe-30wt.%Cr (i.e., including 30wt.%Cr and the balance being Fe) was prepared by electric arc melting of pure iron and pure chromium. The sample was then solution-treated at 1200℃ for 4 hours under an argon atmosphere and rolled to obtain an Fe-Cr based alloy sample with a carbon content of 0.006wt.%. This ensures that the alloy sample has a more uniform composition. Rolling deformation can refine the grains, increase the dislocation density, and improve the mechanical properties of the alloy.

[0056] S2. Use an electrical discharge wire cutting machine to cut the rolled Fe-Cr based alloy sample into 1.5×2×30mm pieces. 3 The internal friction test sample was then polished to 1500 mesh and then placed in a heavy oil stain cleaner for ultrasonic cleaning.

[0057] S3. Fix both ends of the internal friction test sample onto the clamps of the multifunctional inverted torsion pendulum internal friction instrument. To avoid high-temperature oxidation of the alloy sample, maintain a vacuum state in the laboratory. Then heat from room temperature to 900℃ at a rate of 5℃ / min and hold for 10 minutes; then cool to room temperature at the same rate; the test amplitude is kept constant at 2×10. -5 The frequencies were 0.5Hz, 1Hz, 2Hz and 4Hz, and the internal friction value and modulus of the internal friction test sample were measured.

[0058] S4. Plot the internal friction temperature spectrum 1 for the heating and cooling process with temperature as the X-axis and internal friction value and modulus as the Y-axis to complete one in-situ test.

[0059] S5. Repeat steps S3 and S4 to perform in-situ secondary testing to obtain the internal friction temperature spectrum 2.

[0060] S6. Compare internal friction temperature spectrum 1 and internal friction temperature spectrum 2. The characteristic temperature at which the frequency dispersion of the grain boundary relaxation peak weakens or disappears when the temperature rises, accompanied by a sudden increase in internal friction value and a sudden decrease in modulus, is the solid solution temperature of MC-type carbides. The characteristic temperature at which thermal hysteresis occurs when the temperature drops, and the characteristic temperature at which internal friction value drops suddenly and modulus recovers, is the precipitation temperature of MC-type carbides.

[0061] Comparative Example 1

[0062] S1. An alloy sample with a nominal composition of Fe-15wt.%Cr (i.e., including 15wt.%Cr and the balance being Fe) was prepared by electric arc melting of pure iron and pure chromium. The sample was then solution-treated at 1400℃ for 2 hours under an argon atmosphere and rolled to obtain an Fe-Cr based alloy sample with a carbon content of 0.003wt.%.

[0063] S2. Use an electrical discharge wire cutting machine to cut the rolled Fe-Cr based alloy sample into 1.5×2×30mm pieces. 3 The size is determined, and then it is placed in a heavy oil stain cleaner for ultrasonic cleaning.

[0064] S3. Place the cleaned Fe-Cr based alloy sample into a tube furnace and hold it at 800℃, 900℃, and 1000℃ for one hour each under an argon atmosphere. Then cool it with the furnace to allow MC-type carbides to precipitate to varying degrees in the Fe-Cr based alloy sample. Observe the microstructure of the alloy using a scanning electron microscope. Figures 7-9 As shown.

[0065] S4. The dissolution and precipitation temperatures of MC-type carbides were investigated using the forced vibration method: The two ends of the heat-treated alloy sample were fixed to the fixtures of a multifunctional inverted torsional pendulum internal friction apparatus, and a vacuum was maintained in the laboratory. The sample was then heated from room temperature to 800℃ at a rate of 3℃ / min and held for 10 minutes; then cooled to room temperature at the same rate. The test amplitude was kept constant at 2×10⁻⁶. -5 The frequencies are 0.5Hz, 1Hz, 2Hz and 4Hz respectively.

[0066] S5. Plot the internal friction temperature spectrum for the heating and cooling processes, with temperature as the X-axis and internal friction value as the Y-axis, as follows: Figures 3-5 As shown.

[0067] S6. Observe the changes in the morphology and peak position of the grain boundary relaxation peaks of Fe-Cr based alloy samples after annealing at different temperatures, qualitatively determine whether there are precipitates on the grain boundaries, and determine the dissolution and precipitation temperatures of grain boundary MC-type carbides: In the modulus-temperature curve, the characteristic temperature at which the frequency dispersion characteristics of the grain boundary relaxation peaks weaken or disappear with a sudden increase in internal friction and a sudden decrease in modulus when the temperature rises is the solid solution temperature of MC-type carbides; the characteristic temperature at which the internal friction value drops suddenly, the modulus recovers, and the frequency dispersion characteristics of the grain boundary relaxation peaks recover when the temperature drops is the precipitation temperature of MC-type carbides.

[0068] Comparative Example 2

[0069] S1. An alloy sample with a nominal composition of Fe-15wt.%Cr-4wt.%Al (i.e., including 15wt.%Cr and 4wt.%Al, with the balance being Fe) was prepared by electric arc melting of pure iron and pure chromium; the sample was then solution-treated at 1400℃ for 2 hours under an argon atmosphere and rolled to obtain an Fe-Cr-Al based alloy sample with a carbon content of 0.003wt.%.

[0070] S2. Use an electrical discharge wire cutting machine to cut the rolled alloy sample into 1.5×2×30mm pieces. 3 The size is determined, and then it is placed in a heavy oil stain cleaner for ultrasonic cleaning.

[0071] S3. Place the cleaned alloy sample into a tube furnace and hold it at 800℃, 900℃ and 1000℃ for one hour under an argon atmosphere, and then cool it with the furnace to allow MC-type carbides in the alloy sample to precipitate to different degrees.

[0072] S4. The forced vibration method was used to investigate the dissolution and precipitation temperatures of MC-type carbides: The ends of the heat-treated alloy sample were fixed to the fixtures of a multifunctional inverted torsion pendulum internal friction apparatus, and a vacuum was maintained in the laboratory. The sample was then heated from room temperature to 800℃ at a rate of 3℃ / min and held for 10 minutes; then cooled to room temperature at the same rate. The test amplitude was kept constant at 2×10⁻⁶. -5 The frequencies are 0.5Hz, 1Hz, 2Hz and 4Hz respectively.

[0073] S5. Plot the internal friction temperature spectrum for the heating and cooling processes, with temperature as the X-axis and internal friction value as the Y-axis, as follows: Figure 6 As shown.

[0074] S6. Observe the changes in the morphology and peak position of the grain boundary relaxation peaks of the alloy samples after annealing at different temperatures, qualitatively determine whether there are precipitates on the grain boundaries, and determine the dissolution and precipitation temperatures of MC-type carbides at the grain boundaries: In the modulus-temperature curve, the characteristic temperature at which the frequency dispersion characteristics of the grain boundary relaxation peaks weaken or disappear when the temperature rises, accompanied by a sudden increase in internal friction and a sudden decrease in modulus, is the solid solution temperature of MC-type carbides; the characteristic temperature at which the internal friction value drops suddenly, the modulus recovers, and the frequency dispersion characteristics of the grain boundary relaxation peaks recover when the temperature drops is the precipitation temperature of MC-type carbides.

[0075] like Figures 7-9 As shown, for the Fe-15wt.%Cr-based alloy sample (Comparative Example 1), after annealing at 900 °C and 1000 °C, coarse and nearly continuous MC-type carbides were observed to precipitate at the grain boundaries. This resulted in... Figures 3-5 As shown, during the heating process from room temperature to 800 °C, no obvious grain boundary relaxation peaks appeared in the internal friction-temperature spectrum. When the temperature increased to approximately 800 °C, the internal friction value suddenly increased and showed almost no significant dispersion with frequency change, corresponding to the rapid dissolution process of MC-type carbides on the grain boundaries. Subsequently, during the cooling process to approximately 750 °C, the internal friction value suddenly decreased, and MC-type carbides gradually precipitated again as the temperature decreased. SEM observation results showed that the morphology and quantity of MC-type carbides precipitated at grain boundaries increased significantly with increasing annealing temperature, which corroborates the evolution characteristics of the grain boundary peaks in the internal friction measurement.

[0076] In Comparative Example 1, the solid solution temperature of MC-type carbides at the grain boundaries of the alloy sample is about 800℃, the precipitation temperature is about 750℃, and a dissolution-related internal friction peak was detected at about 770℃.

[0077] During the heating process of the internal friction temperature spectrum in the in-situ single test of Example 1, such as Figure 1As shown, there is only one internal friction peak related to recrystallization. During the cooling process, an internal friction peak related to the redeposition of MC-type carbides appeared, but no hysteresis phenomenon could be observed at this time. After performing a second in-situ test, as shown... Figure 2 As shown, Figure 2 The internal friction temperature spectrum is similar to that in Comparative Example 1, showing a significant cooling thermal hysteresis phenomenon. Furthermore, during the heating process, when the temperature reaches 800℃, the internal friction value increases sharply, corresponding to a softening (decrease) of the modulus. This indicates that the MC-type carbides have dissolved, meaning the solution temperature is approximately 800℃. Figure 2 During the cooling process, when the temperature is below 750℃, the internal friction value drops sharply, the modulus increases accordingly, and the internal friction value does not significantly diffuse with frequency. This corresponds to the re-precipitation of MC carbides pinning the grain boundaries, i.e., the precipitation temperature is about 750℃.

[0078] like Figure 10 As shown, after annealing at 800 ℃, almost no MC-type precipitates were observed at the grain boundaries and within the grains of the Fe-15wt.%Cr-4wt.%Al-based alloy sample in Comparative Example 2; Figure 6 As shown, the corresponding internal friction-temperature spectrum shows complete grain boundary relaxation peaks. The peak value increases with increasing test frequency, and the peak position shifts towards higher temperatures as the frequency increases, exhibiting typical grain boundary relaxation frequency dispersion characteristics.

[0079] Fe-Cr based ferromagnetic damping alloys exhibit two main relaxation peaks during heating and cooling: the Zener relaxation peak caused by stress-induced rearrangement of Cr-Cr solute atoms, and the grain boundary relaxation peak caused by grain boundary slip at high temperatures. Molecule carbides (MCs) on the grain boundaries pin the boundaries, hindering grain boundary slip. When MCs precipitate in a coarse or continuous network form, the grain boundary relaxation peaks disappear. When the temperature reaches their solution temperature, the MCs dissolve, and the internal friction of the grain boundary peaks no longer changes with frequency. Therefore, by observing the morphology and peak position of the grain boundary relaxation peaks, it is possible to determine the presence of MC-type carbides on the grain boundaries and their dissolution and precipitation temperatures. Furthermore, the dissolution and precipitation process of grain boundary precipitates with temperature can be observed.

[0080] This invention investigates the change in internal friction of metallic materials with temperature, analyzing that different defect types in metallic materials, such as solute atoms, dislocations, and grain boundaries, exhibit different relaxation peaks. These relaxation peaks can be used to test and analyze information related to defects in metallic materials, obtaining information about defect types, configurations, distributions, solubility, and thermodynamic processes.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for in-situ measurement of the solid solution and precipitation temperatures of MC-type carbides, characterized in that, The specific steps are as follows: S1. Alloy samples were prepared by melting pure iron and pure chromium, and then dissolved at 1200-1400℃ for 2-4 hours under argon atmosphere before rolling to obtain Fe-Cr based alloy samples. S2. Cut and grind the Fe-Cr based alloy sample according to the internal friction sample size to obtain the internal friction test sample, install it on the internal friction measuring instrument, and then heat the internal friction test sample from room temperature to the preset target temperature covering the expected solid solution characteristic temperature range of MC type carbides at a constant heating rate, hold it at the temperature, and then cool it to room temperature. At the same time, measure the internal friction value and modulus of the internal friction test sample. S3. Plot the internal friction temperature spectrum 1 for the heating and cooling processes with temperature as the X-axis and internal friction value and modulus as the Y-axis. S4. Repeat steps S2 and S3 to perform in-situ secondary testing to obtain the internal friction temperature spectrum 2. S5. Compare internal friction temperature spectrum 1 and internal friction temperature spectrum 2. The characteristic temperature at which the frequency dispersion of the grain boundary relaxation peak weakens or disappears when the temperature rises, accompanied by a sudden increase in internal friction value and a sudden decrease in modulus, is the solid solution temperature of MC-type carbides. The characteristic temperature at which thermal hysteresis occurs when the temperature drops, and the characteristic temperature at which internal friction value drops suddenly and modulus recovers, is the precipitation temperature of MC-type carbides.

2. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: The carbon content of the Fe-Cr based alloy sample is ≥0.003 wt.%.

3. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: The chemical composition of the Fe-Cr based alloy sample includes 15-30 wt.% Cr, with the balance being Fe.

4. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: In step S2, the forced vibration mode is used to measure the internal friction value and modulus of the internal friction test sample at a test frequency of 0.1 to 10 Hz.

5. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: In step S2, the constant heating rate is 1-5℃ / min; the preset target temperature is obtained from the iron-chromium alloy phase diagram, and the preset target temperature is 800-900℃, and it is held for 10 minutes, and then cooled to room temperature at the same rate.

6. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 4, characterized in that: In step S2, the amplitude of the forced vibration mode is set to 1×10. -6 ~1×10 -4 .

7. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: In step S2, the internal friction test sample has dimensions of 20–40 mm in length, 1–3 mm in width, and 0.5–2 mm in thickness.

8. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: Step S2 is performed under vacuum or a protective atmosphere.

9. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: In step S2, the cut sample is sanded to 1200-1500 grit using sandpaper.

10. The method for in-situ measurement of the solid solution and precipitation temperature of MC-type carbides according to claim 1, characterized in that: In step S2, the internal friction test sample is ultrasonically cleaned after processing.

Images