Method and device for measuring the penetration depth of an in-situ penetration test of a high-temperature monitored component

Abstract

The application discloses a measurement method and a measurement device for the indentation depth of in-situ indentation testing of a high-temperature monitored component, and comprises the following steps: S10, before the indentation testing, speckle marking is performed on the surface of an indenter; S20, during the indentation testing, a real-time temperature field distribution, a real-time speckle distribution and a real-time indentation load of the surface of the indenter are captured; S30, according to the parameters obtained in the step S20, a formula for calculating the elastic compression deformation of the indenter is fitted; the displacement distribution of the indenter is calculated by using a digital image correlation method, and a displacement change formula of different positions of the indenter is fitted, U=U0+f U (L); S50, according to the formula fitted in the step S40, the overall translation U0 of the indenter is obtained, and the indentation depth h t of the indenter after the flexibility compensation is calculated, wherein h t =U0-ΔL. The measurement method adopts a non-contact method to monitor the deformation of the indenter of an indentation testing machine, combines the temperature distribution, compensates the deformation of the indenter, and ensures the accurate measurement of the real indentation depth.

Description

Technical Field

[0001] This invention relates to the field of material performance testing, and in particular to a method and apparatus for measuring the indentation depth in an in-situ indentation test of a high-temperature monitored component. Background Technology

[0002] Accurate and stable acquisition of the mechanical properties (such as uniaxial tensile properties and fracture toughness) of monitored components can help us more objectively and comprehensively assess the strength and crack propagation resistance of materials in in-service equipment, providing experimental basis for structural integrity assessment and service life extension. Conventional mechanical property tests require large-scale destructive sampling, which is obviously unsuitable for in-service pressure-bearing equipment. Indentation testing, as one of the earliest developed non-destructive mechanical property testing methods, has the advantages of requiring no sampling and having a simple and convenient testing procedure. Furthermore, with its development in recent years, it has been widely adopted in mechanical property evaluation.

[0003] In 1997, Byun et al. from the Department of Metals and Ceramics at Oak Ridge National Laboratory published a paper in the *International Journal of Pressure Vessels and Piping*, Volume 74, Issue 3, pp. 231-238. Building upon extensive summarization of previous research, they developed an instrumented indentation testing machine. This machine is computer-controlled, with a motor-driven spherical indenter repeatedly loading and unloading the material surface. Real-time indentation load-displacement curves are acquired using load sensors and contact displacement sensors. Indentation testing instruments employing contact displacement sensors (LVDTs) have been widely adopted by subsequent researchers due to their simple principle and ease of operation.

[0004] In 2011, Ma Dejun and others published an invention patent entitled "A high-precision instrumented indenter and a method for calculating the depth of diamond indenter indentation into the sample", which also adopted the contact displacement acquisition scheme.

[0005] In 2016, Jin Nanhui published a utility model patent entitled "A Material Mechanical Property Measuring Device and Its Indenter Assembly", which disclosed an optical component for acquiring images of indentations and deformation size data of the tested object. It uses an indenter made of transparent materials such as diamond and obtains the real-time contact area during the indentation test through an optical system, thereby inverting the true indentation depth.

[0006] In existing research schemes, displacement data is acquired through contact. For high-temperature monitored components, direct contact between the indenter or contact displacement sensor and the component under test may damage the optical components at the rear of the indenter or the internal electronic components of the contact displacement sensor. If the indenter is made of high-temperature resistant materials such as tungsten carbide, and the contact displacement sensor is placed far away from the indenter, the elastic compression deformation of the pressure rod assembly at high temperatures will inevitably lead to displacement acquisition errors, thus affecting the accuracy of indentation inversion of mechanical properties. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for measuring the indentation depth of a high-temperature monitored component in situ indentation test. This measurement method uses a non-contact method to monitor the deformation of the pressure bar of the indentation testing machine, and combines the temperature distribution to make flexibility compensation for the deformation of the pressure bar, so as to ensure the accurate measurement of the true indentation depth.

[0008] The present invention also proposes a device for measuring the indentation depth of a high-temperature monitored component in situ indentation test.

[0009] A method for measuring the indentation depth of an in-situ indentation test of a high-temperature monitored component according to a first aspect of the present invention includes: step S10, marking the surface of the pressure bar with speckle patterns before the indentation test; step S20, capturing the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load on the surface of the pressure bar during the indentation test; and step S30, obtaining a formula for calculating the elastic compression deformation of the pressure bar by fitting the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load obtained in step S20, combined with the pressure bar size parameters. Among them, L T Where P is the total length of the compression bar, and E is the real-time compression load. G Let A0 be the high-temperature Young's modulus of the column material, and let A0 be the initial effective load-bearing cross-sectional area of ​​the column before deformation. In step 40, based on the real-time speckle distribution of the high-temperature speckle on the column surface obtained in step S20, the displacement distribution of the column is calculated using digital image correlation. Combined with the material and dimensional parameters of the column, a displacement variation formula for different positions of the column is fitted: U = U0 + f U (L), where U is the displacement of the sampling point at a distance L from the head of the column, U0 is the overall translational value of the column, and f U (L) is a function of the displacement gradient of the column as a function of the distance L from the sampling point to the head of the column; in step S50, the overall translation U0 of the column is obtained according to the formula fitted in step S40, and the insertion depth h of the column after flexibility compensation is calculated. t , where h t =U0-ΔL.

[0010] The in-situ indentation depth measurement method for high-temperature monitored components according to an embodiment of the present invention involves marking the surface of the pressure bar with speckle patterns, then capturing the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load of the pressure bar surface during the pressure test. The elastic deformation and displacement changes at different positions of the pressure bar are obtained by fitting these parameters together with the material and dimensional parameters of the pressure bar. The indentation depth after flexible compensation is then calculated based on the elastic deformation and the overall translational value of the pressure bar. Thus, in a non-contact state, by monitoring the temperature distribution, speckle distribution, and indentation load, flexible compensation is made for the deformation of the pressure bar, improving the accuracy of the indentation depth measurement.

[0011] According to some embodiments of the present invention, step S30 includes: S31, fitting a temperature change function of the pressure bar surface based on the real-time temperature field distribution and real-time speckle distribution obtained in step S20. Where L is the distance between the sampling point and the head of the pressure bar. T t is the distance t represents from the far end of the compression member to the head of the compression member. C The temperature of the pressure bar head;

[0012] S32, Based on the temperature change function obtained in step S31, calculate the Young's modulus E of the compression bar material at different temperatures. G ,in, E is the Young's modulus of the column material at the reference temperature, and t is the temperature of the column surface. r For reference temperature, t m Where m is the melting temperature of the compression bar material, and m is the high-temperature softening index; S32, E calculated according to step S32 G Combined with the indentation load, the elastic compression deformation ΔL of the compression member is calculated.

[0013] According to some embodiments of the present invention, the pressure bar includes a bar segment and a transition segment located at the top of the bar body, wherein the transition segment is connected to the pressure head to form the pressure bar head.

[0014] According to some embodiments of the present invention, the transition section is formed in the shape of a frustum, and the rod section is formed in the form of a hollow structure with a central cavity, the central cavity being adapted to be connected to an external coolant circulation system.

[0015] According to some embodiments of the present invention, the cross-sectional area of ​​the rod segment is S1, the cross-section of the central cavity is S2, the distance between the top end of the central cavity and the top end of the rod segment in the axial direction of the rod segment is h1, the distance between the bottom end of the central cavity and the bottom end of the rod segment in the axial direction of the rod segment is h3, the length of the rod segment in the axial direction is h2, the length of the transition segment is h0, the cross-sectional diameter of the transition segment on the side connecting to the rod segment is D1, and the cross-sectional diameter of the transition segment on the other side away from the rod segment is D2, and the initial effective bearing cross-sectional area A0 of the compression member is:

[0016]

[0017] Where L T =h0+h2.

[0018] According to some embodiments of the present invention, the rod segment is formed into a cuboid structure.

[0019] According to some embodiments of the present invention, the pressure bar is made of ultra-low carbon martensitic aging steel, and a spherical pressure head is connected to the bottom of the pressure bar. The temperature change function of the pressure bar surface is... for: Among them, t C The temperature at the point where the pressure rod contacts the pressure head, C is the fitting coefficient, and 0. <C≤1。

[0020] According to some embodiments of the present invention, in step S10, the speckle is formed on the surface of the pressure bar by high-temperature paint and the average particle size of the speckle is not greater than 1 / 10 of the maximum overall translation value of the pressure bar.

[0021] According to some embodiments of the present invention, in step S20, the real-time temperature field distribution on the surface of the pressure bar is captured by an infrared thermal camera, or the real-time speckle distribution on the surface of the pressure bar is captured by a telecentric lens.

[0022] A device for measuring the indentation depth of a high-temperature monitored component in-situ indentation test according to a second aspect of the present invention includes: a pressure rod, the pressure rod including a rod segment and a transition segment connected to the rod segment, the rod segment being formed as a hollow structure with a cavity adapted to be connected to an external cooling circulation system, and speckle patterns being formed on the outer surface of the pressure rod; a heat capture device configured to capture the real-time temperature distribution on the surface of the pressure rod; a speckle distribution capture device configured to capture the real-time speckle distribution on the surface of the pressure rod; an indentation load sensor configured to obtain the real-time indentation load of the pressure rod; and a processor connected to the heat capture device, the speckle distribution capture device, and the indentation load sensor to fit the elastic compression deformation of the pressure rod and the overall translation value of the pressure rod based on the real-time temperature field distribution, the real-time speckle distribution, the real-time indentation load, and the material parameters and dimensional parameters of the pressure rod, thereby calculating the indentation depth of the pressure rod after flexibility compensation.

[0023] The indentation depth measuring device for in-situ indentation testing of high-temperature monitored components according to an embodiment of the present invention, by setting the pressure rod as a hollow structure with a cavity, introduces an external coolant circulation system for cooling during measurement to ensure that mechanical and electronic components far from the pressure head are always within a safe temperature range. Simultaneously, during the pressure test, the device captures the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load on the pressure rod surface. By fitting these parameters together with the material and dimensional parameters of the pressure rod, the elastic deformation and displacement changes at different positions of the pressure rod are obtained. Then, based on the elastic deformation and the overall translational value of the pressure rod, the indentation depth after flexible compensation is calculated. Thus, in a non-contact state, by monitoring the temperature distribution, speckle distribution, and indentation load, flexible compensation is made for the deformation of the pressure rod, improving the accuracy of the indentation depth measurement.

[0024] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0025] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which will help to understand the purpose and advantages of the present invention, wherein:

[0026] Figure 1 This is a partial schematic diagram of a device for measuring the indentation depth in an in-situ indentation test of a high-temperature monitored component according to an embodiment of the present invention.

[0027] Figure 2A schematic diagram illustrating the application of a method for measuring the indentation depth in an in-situ indentation test of a high-temperature monitored component according to an embodiment of the present invention, using the measurement of the true stress-true strain relationship of SA508 steel at 300°C.

[0028] Figure 3 This is another partial schematic diagram of a device for measuring the indentation depth of a high-temperature monitored component in situ indentation test according to an embodiment of the present invention.

[0029] Figure 4 A schematic diagram of the temperature distribution along the axial direction of the pressure bar surface when applying a method for measuring the indentation depth of an in-situ indentation test of a high-temperature monitored component according to an embodiment of the present invention.

[0030] Figure 5 A schematic diagram of the pressure bar translation-pressure load relationship when applying a method for measuring the indentation depth of a high-temperature monitored component in situ indentation test according to an embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram illustrating the relationship between indentation load and compressive deformation when a method for measuring the indentation depth in an in-situ indentation test of a high-temperature monitored component according to an embodiment of the present invention is applied.

[0032] Figure 7 This is a schematic diagram illustrating the relationship between the actual indentation depth and the indentation load after lever flexibility compensation when applying a method for measuring the indentation depth of a high-temperature monitored component in an in-situ indentation test according to an embodiment of the present invention.

[0033] Figure Labels

[0034] 1. Hollow thick-walled pressure bar; 2. Tungsten carbide spherical indenter; 3. High-temperature steel plate (300℃); 4. Indentation load. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] The following is a reference appendix. Figures 1-7 This invention describes a method for measuring the indentation depth in an in-situ indentation test of a high-temperature monitored component. It should be noted that the high-temperature monitored component described in this invention can refer to a monitored component operating above room temperature (25°C).

[0040] Step S10: Before the indentation test, mark the surface of the pressure bar with speckle markings;

[0041] Step S20, the indentation test process, captures the real-time temperature field distribution, real-time speckle distribution and real-time indentation load of the pressure bar surface;

[0042] Step S30: Based on the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load obtained in step S20, and combined with the column size parameters, a formula for calculating the elastic compressive deformation of the column is fitted. Among them, L T Where P is the total length of the compression bar, and E is the real-time compression load. G A0 is the high-temperature Young's modulus of the column material, and A0 is the initial effective load-bearing cross-sectional area of ​​the column before deformation.

[0043] Step 40: Based on the real-time speckle distribution of the high-temperature resistant speckle on the surface of the compression member obtained in step S20, the displacement distribution of the compression member is calculated using the digital image correlation method. Combined with the material and dimensional parameters of the compression member, a displacement variation formula for different positions of the compression member is fitted: U = U0 + f U (L), where U is the displacement of the sampling point at a distance L from the head of the column, U0 is the overall translational value of the column, and the value of U0 is related to the corresponding real-time pressing load. U0 under the corresponding real-time pressing load is obtained by fitting the displacement variation formula. U (L) is a function of the displacement gradient of the column as a function of the distance L from the sampling point to the head of the column;

[0044] Step S50: Obtain the overall translation value U0 of the compression member based on the formula fitted in step S40, and calculate the compression depth h after flexibility compensation. t, where h t =U0-ΔL.

[0045] The indentation depth measurement method for in-situ indentation testing of high-temperature monitored components according to embodiments of the present invention, compared with the contact method generally used in the prior art, involves speckle marking, followed by capturing the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load of the pressure bar using a non-contact method, and then obtaining a formula based on fitting calculations. The variable parameters are used to calculate the elastic compression deformation of the compression member. At the same time, the displacement change formula of the compression member at different positions is fitted using the above parameters, and the overall translation value of the compression member is obtained. Thus, the elastic compression deformation is used for flexible compensation, improving the accuracy of the indentation depth measurement.

[0046] In some embodiments of the present invention, step S30 includes: S31, fitting a temperature change function of the pressure bar surface based on the real-time temperature field distribution and real-time speckle distribution obtained in step S20. Where L is the distance between the sampling point and the head of the pressure bar. T t is the distance t represents from the far end of the compression member to the head of the compression member. C The temperature at the head of the compression member is obtained by first fitting parameters to the temperature change function of the compression member surface, where L / L is the temperature at the head of the compression member. T With t C All are independent variables, and the specific form of the temperature change function t is obtained by fitting the collected real-time temperature distribution;

[0047] S32, Based on the temperature change function obtained in step S31, calculate the Young's modulus E of the compression bar material at different temperatures. G ,in, E is the Young's modulus of the column material at the reference temperature, and t is the temperature of the column surface. r For reference temperature, t m Where is the melting temperature of the compression bar material, m is the high-temperature softening index, and further, the Young's modulus of the compression bar material at different temperatures is calculated using the temperature change function of S31, while E is the Young's modulus of the compression bar material at the reference temperature. For example, the corresponding Young's modulus of the compression bar material at room temperature (20°C) can be directly obtained by looking up a table.

[0048] S32, E calculated according to step S32 G Then, considering the indentation load, calculate the elastic compressive deformation ΔL of the compression member. Finally, combine this with the Young's modulus E. G The elastic compression deformation ΔL is calculated by combining the real-time applied load P, the initial effective bearing cross-sectional area A0 before the compression bar deforms, and the elastic compression deformation calculation formula.

[0049] Therefore, real-time temperature distribution can be obtained non-contactly, combined with the temperature change function t and Young's modulus E. G The elastic compression deformation ΔL of the pressure bar is calculated using the formula for calculating elastic compression deformation, thereby providing flexible compensation for the indentation depth of the in-situ indentation testing instrument and improving the accuracy and reliability of the measurement.

[0050] like Figure 1 and Figure 3 In some embodiments of the present invention, the pressure bar is mainly composed of a bar segment and a transition segment located at the top of the bar segment. The transition segment is adapted to connect with the pressure head, and the part where the two are connected is formed as the pressure bar head. Thus, by setting the transition segment to connect with the pressure head, for example, the shape and size of the transition segment can be matched according to the size of the pressure head, thereby improving the reliability of the connection between the two.

[0051] Optionally, such as Figure 3 As shown, the transition section is formed into a frustum-shaped structure, and the rod section has a central cavity. Through this central cavity, it can be connected to the external coolant circulation system. Therefore, when measuring high-temperature monitored components, it is possible to avoid directly transferring the high temperature of the component to the pressure load application device through the pressure rod, thus preventing damage to the component due to high temperature.

[0052] In some examples of the present invention, the cross-sectional area of ​​the rod segment is S1, the cross-section of the central cavity is S2, the axial distance between the top end of the central cavity and the top end of the rod segment is h1, the axial distance between the bottom end of the central cavity and the bottom end of the rod segment is h3, the axial length of the rod segment is h2, the length of the transition segment is h0, the cross-sectional diameter of the transition segment on the side connecting to the rod segment is D1, and the cross-sectional diameter of the transition segment on the other side away from the rod segment is D2, and the initial effective bearing cross-sectional area A0 of the compression member is:

[0053]

[0054] Where L T =h0+h2.

[0055] Therefore, the method for measuring the indentation depth of the high-temperature monitored component in the in-situ indentation test according to the present invention, based on the actual shape and size of the pressure bar and considering the actual initial effective bearing cross-sectional area at each position of the pressure bar, further improves the accuracy of flexible compensation.

[0056] In some alternative embodiments of the present invention, the rod segment can be formed into a cuboid structure, for example, as shown below. Figure 3 As shown, the cross-section of the rod segment is square, which facilitates the overall processing and manufacturing.

[0057] Furthermore, the compression bar is made of ultra-low carbon martensitic aging steel, and a spherical indenter is connected to the bottom of the compression bar. Based on the material and dimensional parameters of the compression bar, the temperature change function of the compression bar surface is... The fit is as follows: Among them, t C The temperature at the point where the pressure rod and the pressure head meet is denoted by C, where C is the fitting coefficient and 0 < C ≤ 1.

[0058] In some embodiments of the present invention, in order to accurately obtain the real-time temperature distribution and speckle distribution, the speckle can be formed on the surface of the compression bar by high-temperature paint. At the same time, in order to avoid the speckle particles themselves affecting the deformation of the compression bar, the average particle size of the speckle is not greater than 1 / 10 of the maximum overall displacement value of the compression bar. It should be noted that the overall displacement value U0 of the compression bar is fitted to different values ​​under different real-time pressing loads, and the maximum overall displacement value of the compression bar is the maximum value among the corresponding overall displacement values ​​U0 of the compression bar.

[0059] In some optional examples, in step S20, the real-time temperature field distribution on the surface of the pressure bar is captured by an infrared thermal camera to calculate the temperature change function, or the real-time speckle distribution on the surface of the pressure bar is captured by a telecentric lens to calculate the displacement change at different positions of the pressure bar.

[0060] The following is in conjunction with the appendix Figure 1-7 A measuring apparatus for measuring the indentation depth of a high-temperature monitored component in situ indentation test according to an embodiment of the second aspect of the present invention.

[0061] According to an embodiment of the present invention, a device for measuring the indentation depth of a high-temperature monitored component in situ indentation test includes a pressure rod, a heat capture device, a speckle distribution capture device, an indentation load sensor, and a processor.

[0062] The pressure bar includes a bar segment and a transition segment connected to the bar segment. The bar segment is formed as a hollow structure with a cavity, and the cavity is adapted to be connected to an external cooling circulation system. The outer surface of the pressure bar is formed with speckle, so that the connection between the external cooling circulation system and the cavity can prevent high temperature from being conducted from the high-temperature monitored component to the pressure load application device, etc., and prevent the component from being damaged due to high temperature. The speckle can also facilitate data capture.

[0063] A heat capture device is configured to capture the real-time temperature distribution on the surface of the pressure bar; a speckle distribution capture device is configured to capture the real-time speckle distribution on the surface of the pressure bar; and an indentation load sensor is configured to obtain the real-time indentation load of the pressure bar. The processor fits the elastic compression deformation and overall translation value of the pressure bar based on the real-time temperature field distribution, real-time speckle distribution, real-time indentation load, and the material parameters and size parameters of the pressure bar. The indentation depth of the pressure bar is then flexibly compensated using the elastic compression deformation, thereby obtaining the flexibly compensated indentation depth of the pressure bar.

[0064] The indentation depth measuring device for in-situ indentation testing of high-temperature monitored components according to an embodiment of the present invention, by setting the pressure rod as a hollow structure with a cavity, introduces an external coolant circulation system for cooling during measurement to ensure that mechanical and electronic components far from the pressure head are always within a safe temperature range. Simultaneously, during the pressure test, the device captures the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load on the pressure rod surface. By fitting these parameters together with the material and dimensional parameters of the pressure rod, the elastic deformation and displacement changes at different positions of the pressure rod are obtained. Then, based on the elastic deformation and the overall translational value of the pressure rod, the indentation depth after flexible compensation is calculated. Thus, in a non-contact state, by monitoring the temperature distribution, speckle distribution, and indentation load, flexible compensation is made for the deformation of the pressure rod, improving the accuracy of the indentation depth measurement.

[0065] The following describes, with reference to a specific embodiment, a method for measuring the indentation depth of a high-temperature monitored component in an in-situ indentation test according to an embodiment of the present invention.

[0066] like Figures 1-7 The figure shows the method for measuring the pressing depth of the press rod during the pressing process of a high-temperature steel plate (300℃).

[0067] 10) High-temperature steel plate (300℃) pressing simulation

[0068] 10.1) Simulation principle of high-temperature steel plate (300℃) pressing: Figure 1 As shown. Under indentation load 4, the tungsten carbide spherical indenter 2 at the bottom of the hollow thick-walled compression bar 1 of ultra-low carbon martensitic aging steel C350 is slowly pressed into the high-temperature steel plate (300℃) 3. The indentation simulation process was completed in the finite element analysis software ABAQUS2018. The length, width, and height of the high-temperature steel plate (300℃) are 100mm x 50mm x 20mm, respectively. The true stress-true strain relationship of the material SA508 steel used at 300℃ is as follows. Figure 2 As shown. Considering that the tungsten carbide spherical indenter 2 is in direct contact with the high-temperature steel plate (300℃) 3, heat conduction may damage important components such as the load sensor. Therefore, the pressure rod 1 adopts the following design: Figure 3 The hollow thick-walled structure shown is connected to the external coolant circulation system via a connecting sleeve on the hollow thick-walled pressure rod. Figure 3 (Not shown) to ensure that the load sensor on the side away from the tungsten carbide spherical indenter 2 is always in the appropriate operating temperature range.

[0069] 10.2) The high-temperature steel plate (300℃) pressing simulation process uses displacement control, controlling the downward displacement of the top of the hollow thick-walled pressure bar 1 to be 0.14mm. It should be noted that the 0.14mm in the pressing simulation corresponds to the maximum overall translation U0 of the pressure bar. However, in the actual instrument measurement, the displacement distribution of the pressure bar needs to be calculated using digital image correlation based on the real-time speckle distribution of the high-temperature resistant speckle on the pressure bar surface, and combined with the material and dimensional parameters of the pressure bar, the maximum overall translation U0 of the pressure bar is obtained by fitting.

[0070] In actual testing, the temperature at the top of the hollow thick-walled pressure bar 1 is related to the contact time between the tungsten carbide spherical indenter 2 and the high-temperature steel plate (300℃) 4. As the contact time increases, the temperature at the top of the hollow thick-walled pressure bar 1 first increases and then tends towards a constant value. It is considered that the state when the temperature at the top of the hollow thick-walled pressure bar 1 reaches a constant value represents the steady state under the current heat dissipation conditions (room temperature 20℃, internal cooling water flow rate of the hollow thick-walled pressure bar 1 0.01m / s, and cooling water temperature at the top inlet of the hollow thick-walled pressure bar 1 20℃). Based on the actual time consumed in the indentation test, the contact time is set to 10 minutes. At this time, the temperature distribution along the axial direction of the hollow thick-walled pressure bar surface is as follows: Figure 4 As shown, the following formula is used for fitting.

[0071]

[0072] In the formula, L is the distance between the temperature sampling point and the top of the hollow thick-walled pressure bar. T The hollow, thick-walled compression member has a total length of 120mm and a t. C The temperature at the junction of the hollow thick-walled pressure bar and the pressure head (here set to the high-temperature steel plate temperature t) is the temperature at which the pressure bar meets the pressure head. C =300℃), C is the fitting coefficient 0.091.

[0073] 10.3) The actual indentation depth of the tungsten carbide spherical indenter 2 into the high-temperature steel plate (300℃) 3 is affected by two factors: one is the translation of the indentation rod driven by the indentation load, and the other is the compression deformation of the indentation rod caused by the indentation load. For the simulation process of indentation into the high-temperature steel plate (300℃), the displacement of the top of the hollow thick-walled indenter is the translation of the indenter, and the corresponding force on the top of the hollow thick-walled indenter is the indentation load. The indentation load-indentation load curve is shown in the figure below. Figure 5 As shown.

[0074] 20) Calculate the elastic compressive deformation of a hollow thick-walled compression member.

[0075] 20.1) The effect of high temperature on the Young's modulus of ultra-low carbon martensitic aging steel C350 used in hollow thick-walled compression bars is described by the following formula.

[0076]

[0077] In the formula, E is the known Young's modulus of ultra-low carbon martensitic aging steel C350 at room temperature (for ultra-low carbon martensitic aging steel C350, E = 205 GPa), E G This refers to the Young's modulus of ultra-low carbon martensitic aging steel C350 at high temperature, which needs to be fitted. t is the pressure bar temperature. r For reference temperature, it is set here to the temperature at the far end of the compression rod (i.e., L / L). T Position, t r =20℃). t m The melting temperature of ultra-low carbon martensitic aging steel C350 (for ultra-low carbon martensitic aging steel C350, t) m =1515℃), m is the high temperature softening index (for ultra-low carbon martensitic aging steel C350, m = 1.00).

[0078] 20.2) Combined with the indentation load, calculate the curve of elastic compression deformation ΔL of the hollow thick-walled column as a function of the indentation load, as shown in the following formula.

[0079]

[0080] In the formula, L T The total length of the compression bar is 120mm, P is the real-time compression load read by the load sensor connected in series with the compression bar, and E... G A0 is the high-temperature Young's modulus of the ultra-low carbon martensitic aging steel C350 used in the hollow thick-walled compression bar determined in step 20.1). Figure 3 The initial effective load-bearing cross-sectional area of ​​the hollow thick-walled compression member before deformation can be characterized by a piecewise function as shown in the following formula.

[0081]

[0082] In the formula, L is the distance between the temperature sampling point and the top of the hollow thick-walled pressure bar. T The total length of the hollow, thick-walled compression bar is 120mm.

[0083] 30) Obtain the actual indentation depth of the hollow thick-walled column after compliance compensation.

[0084] 30.1) Actual indentation depth h of hollow thick-walled compression bar after slenderness compensation t It is calculated using the following formula.

[0085] h t =U0-ΔL

[0086] 30.2) Using the actual indentation depth of the hollow thick-walled column after slenderness compensation as the abscissa and the indentation load at the corresponding moment as the ordinate, plot as follows: Figure 7 The actual indentation depth-indentation load curve shown can be directly used in the indentation inversion theory of existing material properties to obtain the mechanical properties of the tested material.

[0087] Compared with the prior art, the beneficial effects of the present invention are:

[0088] (1) The non-contact displacement acquisition scheme of the present invention can avoid sensor damage caused by high temperature contact;

[0089] (2) The hollow thick-walled structure of the pressure bar described in this invention can be connected to an external coolant circulation system, which can not only avoid damage to the load sensor at the top of the pressure bar caused by heat conduction, but also reduce the high-temperature softening of the pressure bar and improve the rigidity of the test system.

[0090] (3) The compression bar deformation measurement based on digital image correlation method described in this invention can accurately obtain the overall translation of the compression bar;

[0091] (4) The real-time temperature field distribution on the surface of the pressure bar captured by the infrared thermal imaging camera described in this invention can better calculate the high-temperature deformation of the pressure bar.

[0092] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for measuring the indentation depth in an in-situ indentation test of a high-temperature monitored component, characterized in that, include: Step S10: Before the indentation test, mark the surface of the pressure bar with speckle markings; Step S20, the indentation test process, captures the real-time temperature field distribution, real-time speckle distribution and real-time indentation load of the pressure bar surface; Step S30: Based on the real-time temperature field distribution, real-time speckle distribution, and real-time indentation load obtained in step S20, and combined with the column size parameters, a formula for calculating the elastic compressive deformation of the column is fitted. ,in, L T The total length of the compression bar P To apply the load in real time, E G The high-temperature Young's modulus of the compression bar material. A 0 represents the initial effective load-bearing cross-sectional area of ​​the compression member before deformation; Step 40: Based on the real-time speckle distribution of the high-temperature resistant speckle on the surface of the compression member obtained in step S20, the displacement distribution of the compression member is calculated using the digital image correlation method. Combined with the material and dimensional parameters of the compression member, a formula for the displacement variation at different positions of the compression member is fitted to obtain the final result. ,in, U The distance from the sampling point to the head of the pressure bar L Displacement at that point U 0 represents the overall translation value of the compression member. f U ( L The displacement gradient of the column varies with the distance from the sampling point to the head of the column. L The function of change; Step S50: Obtain the overall translation of the compression bar according to the formula fitted in step S40. U 0, calculate the insertion depth of the compression bar after flexibility compensation. h t ,in, .

2. The method for measuring the indentation depth of the high-temperature monitored component in situ indentation test according to claim 1, characterized in that, Step S30 includes: S31, Based on the real-time temperature field distribution and real-time speckle distribution obtained in step S20, fit the temperature change function of the pressure bar surface. Where L is the distance between the sampling point and the head of the pressure bar. L T This is the distance from the far end of the compression member to the head of the compression member. t C The temperature of the pressure bar head; S32, Based on the temperature change function obtained in step S31, calculate the Young's modulus of the compression bar material at different temperatures. E G ,in, , E It is the Young's modulus of the compression bar material at the reference temperature. t The temperature of the pressure bar surface. t r For reference temperature, t m The melting temperature of the pressure bar material. m The high-temperature softening index; S32, calculated according to step S32 E G Δ, the elastic compressive deformation of the compression member is calculated by combining the indentation load. L .

3. The method for measuring the indentation depth of the high-temperature monitored component in in-situ indentation test according to claim 2, characterized in that, The pressure bar includes a bar segment and a transition segment located at the top of the bar body. The position where the transition segment connects with the pressure head forms the pressure bar head.

4. The method for measuring the indentation depth of the high-temperature monitored component in situ indentation test according to claim 3, wherein the transition section is formed in the shape of a frustum cone, the rod section is formed in the shape of a hollow structure with a central cavity, and the central cavity is adapted to be connected to an external coolant circulation system.

5. The method for measuring the indentation depth of the high-temperature monitored component in in-situ indentation test according to claim 4, characterized in that, The cross-sectional area of ​​the rod segment is S1, the cross-sectional area of ​​the central cavity is S2, the axial distance between the top end of the central cavity and the top end of the rod segment is h1, the axial distance between the bottom end of the central cavity and the bottom end of the rod segment is h3, the axial length of the rod segment is h2, the length of the transition segment is h0, the cross-sectional diameter of the transition segment on the side connecting to the rod segment is D1, and the cross-sectional diameter of the transition segment on the other side away from the rod segment is D2, and the initial effective bearing cross-sectional area of ​​the compression member is... A 0 is: in L T =h0+h2.

6. The method for measuring the indentation depth of the high-temperature monitored component in in-situ indentation test according to claim 4, characterized in that, The rod segment is formed into a cuboid structure.

7. The method for measuring the indentation depth of the in-situ indentation test of the high-temperature monitored component according to claim 6, characterized in that, The pressure bar is made of ultra-low carbon martensitic aging steel, and a spherical pressure head is connected to the bottom of the pressure bar. The temperature change function of the pressure bar surface is... for: ,in, t C The temperature at the point where the pressure rod and the pressure head meet is denoted by C, where C is the fitting coefficient and 0 < C ≤ 1.

8. The method for measuring the indentation depth of the high-temperature monitored component in in-situ indentation test according to claim 2, characterized in that, In step S10, the speckle is formed on the surface of the pressure bar by high-temperature paint and the average particle size of the speckle is not greater than 1 / 10 of the maximum overall translation value of the pressure bar.

9. The method for measuring the indentation depth of the high-temperature monitored component in in-situ indentation test according to claim 5, characterized in that, In step S20, the real-time temperature field distribution on the surface of the pressure bar is captured by an infrared thermal camera, or the real-time speckle distribution on the surface of the pressure bar is captured by a telecentric lens.

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