A fatigue testing device for high temperature resistant metal materials

Abstract

The present invention belongs to the technical field of material fatigue testing, and particularly relates to a fatigue testing device for high temperature resistant metal materials. It includes a base, a motion driving mechanism, a vacuum chamber, a heating sleeve assembly, a test piece fixing assembly and a variable load mechanism, wherein the motion driving mechanism and the vacuum chamber are both arranged on the base, and the motion driving mechanism is used to drive the vacuum chamber to reciprocate linearly relative to the base; the vacuum chamber includes a test chamber and a variable load chamber, the variable load mechanism is arranged in the variable load chamber, the heating sleeve assembly and the test piece fixing assembly are arranged in the test chamber, the test piece fixing assembly is used to fix an ultra-high temperature test piece, and the test piece fixing assembly is connected to the variable load mechanism, and the heating sleeve assembly is used to heat and temperature control the ultra-high temperature test piece; the variable load mechanism passively loads an alternating load on the ultra-high temperature test piece with the reciprocating linear motion of the vacuum chamber. The present invention has a simple structure, a small volume, and good sealing, which improves the reliability and accuracy of fatigue testing.

Description

Technical Field

[0001] The invention belongs to the technical field of material fatigue testing, and in particular relates to a high-temperature resistant metal material fatigue testing device. Background Art

[0002] Ultra-high temperature materials refer to the most heat-resistant advanced materials that can be used normally in harsh working environments such as stress and oxidation, and in high temperatures exceeding 2000°C. Commonly used ultra-high temperature materials include three categories: ceramic-based composites, refractory metals, and C / C composites.

[0003] The refractory metals of ultra-high temperature materials are mainly tungsten, molybdenum, tantalum, niobium, zirconium and other alloys. Tungsten-molybdenum alloys have the advantages of high melting point, good thermal shock resistance, strong corrosion resistance, etc., and have become important high-temperature structural materials and functional materials. Tungsten-molybdenum alloys have excellent properties such as good thermal conductivity, electrical conductivity, high-temperature strength and creep resistance at high temperatures, and are widely used in important high-temperature environments. Therefore, ultra-high temperature fatigue tests are required for tungsten-molybdenum alloys.

[0004] After studying the existing domestic and foreign fatigue test public literature, the main existing technical route investigated is to connect the loading device (alternating load or high-frequency ultrasonic load generator) to the ultra-high temperature test piece in series through the force sensor, water-cooling sleeve, and fixture. One end of the water-cooling sleeve is on the external atmosphere side, and the other end of the water-cooling sleeve is on the vacuum or non-oxidizing atmosphere side. The water-cooling sleeve needs to have a dynamic seal with the vacuum furnace. Common dynamic seals include water-cooled magnetic fluid, sealing rings or bellows.

[0005] The existing main technical route solutions investigated have the following technical aspects to be optimized: First, because the water-cooling sleeve needs to be very long to deal with high-temperature alloy test pieces exceeding 2000℃, the size of the entire vacuum furnace is large, the purchase cost is high, and the water cooling energy consumption is high and the cost of use is high. Secondly, the connection gap between the high-temperature alloy test piece and the fixture is a difficult problem in the existing technology, which greatly affects the accuracy of alternating load loading. Finally, the dynamic sealing resistance of the water-cooling sleeve is very large, and the dynamic sealing cost is high. The dynamic sealing resistance of the water-cooling sleeve affects the applied alternating load and affects the accuracy of the test load. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a high-temperature resistant metal material fatigue testing device to solve the problems that the existing device needs to have a very long water-cooling sleeve to cope with high-temperature alloy test pieces exceeding 2000°C, so the size of the entire vacuum furnace is large, the purchase cost is high, and the dynamic sealing resistance of the water-cooling sleeve affects the test load accuracy.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a high-temperature resistant metal material fatigue testing device, comprising a base, a motion driving mechanism, a vacuum chamber, a heating sleeve assembly, a test piece fixing assembly and a variable load mechanism, wherein the motion driving mechanism and the vacuum chamber are both arranged on the base, the motion driving mechanism is connected to the vacuum chamber, and the motion driving mechanism is used to drive the vacuum chamber to reciprocate linearly relative to the base; the vacuum chamber comprises a test chamber and a variable load chamber, the variable load mechanism is arranged in the variable load chamber, the heating sleeve assembly and the test piece fixing assembly are arranged in the test chamber, the test piece fixing assembly is used to fix an ultra-high temperature test piece, and the test piece fixing assembly passes through a through hole between the test chamber and the variable load chamber and is connected to the variable load mechanism, and the heating sleeve assembly is used to heat and temperature-control the ultra-high temperature test piece; the variable load mechanism passively loads an alternating load on the ultra-high temperature test piece with the reciprocating linear motion of the vacuum chamber.

[0009] In one possible implementation, the test piece fixing assembly includes a connecting column I, a connecting column II and two tungsten-molybdenum alloy locking pins, wherein one end of the connecting column I is connected to the vacuum chamber, the connecting column II passes through the through hole between the test chamber and the variable load chamber, one end of the connecting column II is connected to the variable load mechanism, and the ultra-high temperature test piece is connected to the other ends of the connecting column I and the connecting column II through two tungsten-molybdenum alloy locking pins, and the connecting column I and the connecting column II are coaxial.

[0010] In a possible implementation, the other end of the connecting column I is provided with an axial end hole I and a radial hole I vertically penetrating the axial end hole I; the other end of the connecting column II is provided with an axial end hole II and a radial hole II vertically penetrating the axial end hole II;

[0011] The two ends of the ultra-high temperature test piece are respectively inserted into the axial end hole I of the connecting column I and the axial end hole II of the connecting column II. The two ends of the ultra-high temperature test piece are respectively provided with a left connecting hole and a right connecting hole in the radial direction. The left connecting hole is connected to the radial hole I through a tungsten-molybdenum alloy locking pin, and the right connecting hole is connected to the radial hole II through another tungsten-molybdenum alloy locking pin.

[0012] In a possible implementation, the connection column I, the connection column II, the ultra-high temperature test piece and the two tungsten-molybdenum alloy locking pins are assembled by cold installation thermal expansion interference connection.

[0013] In one possible implementation, the heating sleeve assembly includes a reflective tube, a bracket, a water-cooled heating coil and a graphite sleeve, wherein the graphite sleeve, the water-cooled heating coil and the reflective tube are coaxially mounted in sequence from the inside to the outside, and the reflective tube is fixed to the inner wall of the vacuum chamber through the bracket; the ultra-high temperature test piece passes through the inner cavity of the graphite sleeve; and the reflective tube is used to reflect the thermal radiation of the graphite sleeve inward.

[0014] In a possible implementation, radial gaps are provided between inner walls at both ends of the reflective tube and the connecting pillars I and II; and the reflective tube is made of ultra-high temperature ceramics.

[0015] In one possible implementation, the water-cooled heating coil is a hollow structure containing a cold water channel therein.

[0016] In one possible implementation, the variable load mechanism includes a spring I, a vibrator and a spring II, wherein the vibrator is slidably matched with the inner wall of the variable load cavity, spring I and spring II are respectively arranged on both sides of the vibrator, and one end of spring I and spring II are connected to the vibrator, and the other ends of spring I and spring II are respectively connected to the vacuum cavity and the connecting column II.

[0017] In one possible implementation, the high-temperature resistant metal material fatigue testing device further includes a non-contact measuring mechanism, an observation window is provided on the side wall of the vacuum chamber, and a measuring through hole is provided on the side wall of the heating sleeve assembly. The detection light emitted by the non-contact measuring mechanism passes through the observation window and the measuring through hole of the heating sleeve assembly and then irradiates the ultra-high temperature test piece.

[0018] In a possible implementation, the vacuum chamber includes a cylinder and a left cover and a right cover arranged at both ends of the cylinder; a drag chain mechanism is provided on one side of the cylinder.

[0019] The advantages and beneficial effects of the present invention are: a high-temperature resistant metal material fatigue testing device provided by the present invention drives the vacuum chamber as a whole to perform periodic reciprocating motion through a motion driving mechanism, and a variable load mechanism in the vacuum chamber enables the ultra-high temperature test piece to obtain periodic alternating axial tensile and compressive loads based on mechanical vibration, thereby improving the loading accuracy of the alternating load, and the test results are reliable and the test accuracy is high.

[0020] The invention has the advantages of simple structure, small volume, good sealing performance and low cost; a physical static seal is used to isolate the external power from the alternating load loading of the internal high-temperature alloy test piece, thus avoiding the problem of reducing the test accuracy due to the use of dynamic seals.

[0021] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 This is one of the axonometric views of a high temperature resistant metal material fatigue testing device of the present invention;

[0025] Figure 2 This is the second isometric view of a high temperature resistant metal material fatigue testing device of the present invention;

[0026] Figure 3 This is a schematic diagram of the internal structure of a high temperature resistant metal material fatigue testing device of the present invention;

[0027] Figure 4 for Figure 3 A partial enlarged view of point A in the middle.

[0028] In the figure: 1-base, 2-motion drive mechanism, 201-drive housing, 202-drive end, 3-vacuum chamber, 301-left cover, 302-cylinder, 303-right cover, 304-observation window, 305-spring I, 306-oscillator, 307-spring II, 4-drag chain mechanism, 5-non-contact measurement mechanism, 6-connecting column I, 601-radial hole I, 602-axial end hole I, 7-tungsten-molybdenum alloy locking pin, 8-ultra-high temperature test piece, 801-middle test thin diameter, 802-end clamping thick diameter, 803-left connecting hole, 804-right connecting hole, 9-connecting column II, 901-radial hole II, 902-axial end hole II, 10-reflecting cylinder, 11-bracket, 12-water-cooled heating coil, 13-graphite sleeve, 14-radial measuring small hole I, 15-radial measuring small hole II, 16-detection light. DETAILED DESCRIPTION

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] An embodiment of the present invention provides a high temperature resistant metal material fatigue test device, which has a simple structure, a small volume, and good sealing performance, thereby improving the reliability and accuracy of fatigue test results. Figures 1 to 4 As shown, the high-temperature resistant metal material fatigue testing device includes a base 1, a motion driving mechanism 2, a vacuum chamber 3, a heating sleeve assembly, a test piece fixing assembly and a variable load mechanism, wherein the motion driving mechanism 2 and the vacuum chamber 3 are both arranged on the base 1, the motion driving mechanism 2 is connected to the vacuum chamber 3, and the motion driving mechanism 2 is used to drive the vacuum chamber 3 to reciprocate linearly relative to the base 1; the vacuum chamber 3 includes a test chamber and a variable load chamber, the variable load mechanism is arranged in the variable load chamber, the heating sleeve assembly and the test piece fixing assembly are arranged in the test chamber, the test piece fixing assembly is used to fix the ultra-high temperature test piece 8, and the test piece fixing assembly passes through the through hole between the test chamber and the variable load chamber and is connected to the variable load mechanism, and the heating sleeve assembly is used to heat and temperature-control the ultra-high temperature test piece 8; the variable load mechanism passively loads the ultra-high temperature test piece 8 with an alternating load as the vacuum chamber 3 reciprocates linearly.

[0032] See also Figure 3 As shown, in an embodiment of the present invention, the vacuum chamber 3 includes a cylinder 302 and a left cover 301 and a right cover 303 detachably connected to both ends of the cylinder 302, and the bottom of the cylinder 302 is connected to the base 1 through a guide rail slider so as to move on the base 1. The left cover 301, the cylinder 302 and the right cover 303 all contain a water cooling structure, which can maintain the external temperature at room temperature. The interior of the cylinder 302 is axially divided into a test chamber and a variable load chamber, and a through hole is left between the test chamber and the variable load chamber. An observation window 304 is provided on the side wall of the test chamber, and the observation window 304 can also be removed during the assembly process. A drag chain mechanism 4 is provided on one side of the cylinder 302, and the drag chain mechanism 4 provides cooling circulating water, heating current, etc. to the moving vacuum chamber 3.

[0033] See also Figure 3 , Figure 4 As shown, in an embodiment of the present invention, the test piece fixing assembly includes a connecting column I6, a connecting column II9 and two tungsten-molybdenum alloy locking pins 7, wherein one end of the connecting column I6 is connected to the vacuum chamber 3, the connecting column II9 passes through the through hole between the test chamber and the variable load chamber, one end of the connecting column II9 is ​​connected to the variable load mechanism, and the ultra-high temperature test piece 8 is connected to the other ends of the connecting column I6 and the connecting column II9 through the two tungsten-molybdenum alloy locking pins 7, and the connecting column I6 and the connecting column II9 are coaxial.

[0034] Specifically, the other end of the connecting column I6 is provided with an axial end hole I602 and a radial hole I601 vertically penetrating the axial end hole I602; the other end of the connecting column II9 is ​​provided with an axial end hole II902 and a radial hole II901 vertically penetrating the axial end hole II902; the two ends of the ultra-high temperature test piece 8 are respectively inserted into the axial end hole I602 of the connecting column I6 and the axial end hole II902 of the connecting column II9, and the two ends of the ultra-high temperature test piece 8 are respectively provided with a left connecting hole 803 and a right connecting hole 804 in the radial direction, the left connecting hole 803 is connected to the radial hole I601 through a tungsten-molybdenum alloy locking pin 7, and the right connecting hole 804 is connected to the radial hole II901 through another tungsten-molybdenum alloy locking pin 7. Preferably, the tungsten-molybdenum alloy locking pin 7 is cylindrical.

[0035] Preferably, the connection column Ⅰ6, the connection column Ⅱ9, the ultra-high temperature test piece 8 and the two tungsten-molybdenum alloy locking pins 7 are assembled by cold installation thermal expansion interference connection. Preferably, the material of the connection column Ⅰ6 and the connection column Ⅱ9 is ultra-high temperature ceramic. The ultra-high temperature test piece 8 is a rotating body with a dumbbell shape, including a middle test fine diameter 801 and an end clamping thick diameter 802 at both ends. The end clamping thick diameter 802 is provided with a left connection hole 803 and a right connection hole 804. The side connection hole 803 and the right connection hole 804 are orthogonal to the axis of the ultra-high temperature test piece 8, see Figure 4 In this embodiment, the material of the ultra-high temperature test piece 8 is an ultra-high temperature tungsten-molybdenum alloy.

[0036] Specifically, the assembly process between the connecting column I 6, the connecting column II 9, the ultra-high temperature test piece 8 and the two tungsten-molybdenum alloy locking pins 7 is as follows:

[0037] At room temperature, one end of the ultra-high temperature test piece 8 is clamped with a thick diameter 802 and inserted into the shaft end hole Ⅰ602 of the connecting column Ⅰ6, and the tungsten-molybdenum alloy locking pin 7 adopts a cold installation process. The cold installation process is to place a part in liquid nitrogen for a process time, and then place the part into the process hole of another part with a gap. When the two parts reach the same temperature, there is an interference fit between the two parts. The cold installation process can be simulated and analyzed by a set of mature software. If the interference is too large, the mating surface is easy to collapse; if the interference is too small, the friction generated by the interference is not enough.

[0038] In this embodiment, the cold assembly process includes two simulation calculations of cold assembly of the tungsten-molybdenum alloy locking pin 7 and the left connecting hole 803 of the ultra-high temperature test piece 8. The two simulation calculations include but are not limited to the first simulation calculation that at room temperature, the tungsten-molybdenum alloy locking pin 7 and the left connecting hole 803 have an interference fit that cannot be crushed, and maintain relative friction interference extrusion locking; the tungsten-molybdenum alloy locking pin 7 has a clearance fit with the radial hole Ⅰ601 of the connecting column Ⅰ6. The second simulation calculation is that at the test temperature of 2500℃, the tungsten-molybdenum alloy locking pin 7 has an interference fit with the radial hole Ⅰ601 of the connecting column Ⅰ6 and the left connecting hole 803 that cannot be crushed, and maintain relative friction interference extrusion locking.

[0039] At room temperature, the tungsten-molybdenum alloy locking pin 7 and the left connecting hole 803 of the ultra-high temperature test piece 8 are assembled by freezing the tungsten-molybdenum alloy locking pin 7 with liquid nitrogen, placing the frozen tungsten-molybdenum alloy locking pin 7 in the left connecting hole 803 of the ultra-high temperature test piece 8, and cold-fitting. For a short time, the tungsten-molybdenum alloy locking pin 7 and the left connecting hole 803 of the ultra-high temperature test piece 8 are clearance fit. When the tungsten-molybdenum alloy locking pin 7 and the left connecting hole 803 of the ultra-high temperature test piece 8 reach room temperature, the tungsten-molybdenum alloy locking pin 7 and the left connecting hole 803 become interference fit.

[0040] The double simulation calculations use the principle that the expansion coefficient of ultra-high temperature ceramics is inconsistent with the expansion coefficient of ultra-high temperature tungsten-molybdenum alloy. Under room temperature assembly, the tungsten-molybdenum alloy locking pin 7 and the radial hole Ⅰ601 of the connecting column Ⅰ6 are clearance fit. When the test temperature is 2500℃, the tungsten-molybdenum alloy locking pin 7 and the radial hole Ⅰ601 of the connecting column Ⅰ6 are interference fit without clearance. The assembly of the other tungsten-molybdenum alloy locking pin 7 with the connecting column Ⅱ9 and the ultra-high temperature test piece 8 is similar.

[0041] See also Figure 4 As shown, in the embodiment of the present invention, the heating sleeve assembly includes a reflective tube 10, a bracket 11, a water-cooled heating coil 12 and a graphite sleeve 13, wherein the graphite sleeve 13, the water-cooled heating coil 12 and the reflective tube 10 are coaxially mounted in sequence from the inside to the outside, and the reflective tube 10 is fixed to the inner wall of the vacuum chamber 3 through the bracket 11; the ultra-high temperature test piece 8 passes through the inner cavity of the graphite sleeve 13; the reflective tube 10 is used to reflect the heat radiation of the graphite sleeve 13 inwardly.

[0042] Furthermore, radial gaps are provided between the inner walls of both ends of the reflector tube 10 and the connecting pillars I6 and II9; the reflector tube 10 is made of ultra-high temperature ceramics. The water-cooled heating coil 12 is hollow and contains a cooling water channel. The outer surface of the water-cooled heating coil 12 is mirror-plated with silver to minimize the heat input of thermal radiation. The water-cooled heating coil 12 heats the graphite sleeve 13 to a controllable temperature of 2000°C to 3000°C through a high-frequency electromagnetic field. The reflector tube 10 effectively reflects the thermal radiation of the graphite sleeve 13, thereby improving the utilization rate of energy.

[0043] See also Figure 3 As shown, in the embodiment of the present invention, the variable load mechanism includes a spring I 305, a vibrator 306 and a spring II 307, wherein the vibrator 306 is slidably matched with the inner wall of the variable load cavity, the spring I 305 and the spring II 307 are respectively arranged on both sides of the vibrator 306, and one end of the spring I 305 and the spring II 307 are both connected to the vibrator 306, and the other ends of the spring I 305 and the spring II 307 are respectively connected to the vacuum cavity 3 and the connecting column II 9. The elastic force of the spring I 305 and the spring II 307 forms a micro preload on the ultra-high temperature test piece 8, and the vibrator 306 is preferably cylindrical, and the vibrator 306 and the vacuum cavity 3 form a cylindrical pair.

[0044] See also Figure 2 , Figure 4 As shown, in an embodiment of the present invention, the high temperature resistant metal material fatigue testing device also includes a non-contact measuring mechanism 5, an observation window 304 is provided on the side wall of the vacuum chamber 3, and a measuring through hole is provided on the side wall of the heating sleeve assembly. The detection light 16 emitted by the non-contact measuring mechanism 5 passes through the observation window 304 and the measuring through hole of the heating sleeve assembly and then irradiates the ultra-high temperature test piece 8.

[0045] Specifically, see Figure 4 As shown, coaxial radial measuring holes Ⅰ14 and Ⅱ15 are respectively provided on the side walls of the graphite sleeve 13 and the reflecting tube 10 corresponding to the observation window 304, and the detection light 16 sent by the non-contact measuring mechanism 5 passes through the radial measuring holes Ⅱ15 and Ⅰ14.

[0046] See also Figure 2 As shown, in the embodiment of the present invention, the driving housing 201 of the motion driving mechanism 2 is connected to the base 1, and the driving end 202 of the motion driving mechanism 2 is connected to the left cover 301, and the vacuum chamber 3 is driven to reciprocate through the driving end 202. The vacuum chamber 3 reciprocates periodically relative to the ground. According to mechanical vibration, from the perspective of steady-state forced vibration response, the ultra-high temperature test piece 8 will obtain periodic alternating axial tensile and compressive loads.

[0047] Specifically, the non-contact measuring mechanism 5 is fixed to the outside of the base 1. The non-contact measuring mechanism 5 includes but is not limited to purchased commercial products such as digital image analysis, dual colorimetric infrared thermometer, digital speckle, and high-speed camera. The detection light 16 emitted by the non-contact measuring mechanism 5 enters the test chamber through the quartz glass on the observation window 304, the radial measurement hole II15 of the reflective tube 10, the spiral gap of the water-cooled heating coil 12, and the radial measurement hole I14 on the graphite sleeve 13 in turn, and measures the temperature of the middle test diameter 801 of the ultra-high temperature test piece 8, and forms a closed-loop temperature control system. The non-contact measuring mechanism 5 uses digital image analysis technology to determine whether the relative position of the radial hole II901 of the connecting column II9 and the reflective tube 10 is correct, and to determine the time point of fatigue fracture of the ultra-high temperature test piece 8.

[0048] The present invention provides a high temperature resistant metal material fatigue test device, which drives the vacuum chamber as a whole to perform periodic reciprocating motion through a motion driving mechanism. The variable load mechanism in the vacuum chamber, based on mechanical vibration, enables the ultra-high temperature test piece to obtain periodic alternating axial tensile and compressive loads, thereby improving the accuracy of alternating load loading, and the test results are reliable and the test accuracy is high. The present invention has a simple structure, a small volume, good sealing, and low cost; the vacuum chamber 3 is a sealed structure as a whole, the vacuum furnace shell has no dynamic seal, and there is no problem of transmission sealing inside and outside the furnace. Physical static sealing is used to isolate the external power from the alternating load loading of the internal high temperature alloy test piece, thereby avoiding the problem of reducing the test accuracy due to the use of dynamic seals.

[0049] The present invention effectively solves the problem in the prior art that the connection gap between the high-temperature alloy test piece and the fixture greatly affects the accuracy of alternating load loading. The present invention introduces a cold-loading thermal expansion process to ensure that the high-temperature alloy test piece and the fixture fit without gaps at 2500°C. In addition, the present invention effectively solves the problem that the dynamic sealing resistance of the existing water-cooling sleeve is large, affecting the test load accuracy and the high cost of dynamic sealing.

[0050] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high temperature resistant metal material fatigue testing device, characterized in that: The invention comprises a base (1), a motion drive mechanism (2), a vacuum chamber (3), a heating sleeve assembly, a test piece fixing assembly and a variable load mechanism, wherein the motion drive mechanism (2) and the vacuum chamber (3) are both arranged on the base (1), the motion drive mechanism (2) is connected to the vacuum chamber (3), and the motion drive mechanism (2) is used to drive the vacuum chamber (3) to reciprocate linearly relative to the base (1); the vacuum chamber (3) comprises a test chamber and a variable load chamber, the variable load mechanism is arranged in the variable load chamber, the heating sleeve assembly and the test piece fixing assembly are arranged in the test chamber, the test piece fixing assembly is used to fix an ultra-high temperature test piece (8), and the test piece fixing assembly passes through a through hole between the test chamber and the variable load chamber and is connected to the variable load mechanism, and the heating sleeve assembly is used to heat and temperature-control the ultra-high temperature test piece (8); the variable load mechanism passively loads an alternating load on the ultra-high temperature test piece (8) as the vacuum chamber (3) reciprocates linearly; The test piece fixing assembly comprises a connecting column I (6), a connecting column II (9) and two tungsten-molybdenum alloy locking pins (7), wherein one end of the connecting column I (6) is connected to the vacuum chamber (3), the connecting column II (9) passes through the through hole between the test chamber and the variable load chamber, one end of the connecting column II (9) is connected to the variable load mechanism, the ultra-high temperature test piece (8) is connected to the other ends of the connecting column I (6) and the connecting column II (9) through the two tungsten-molybdenum alloy locking pins (7), and the connecting column I (6) and the connecting column II (9) are coaxial; The other end of the connecting column I (6) is provided with an axial end hole I (602) and a radial hole I (601) vertically penetrating the axial end hole I (602); the other end of the connecting column II (9) is provided with an axial end hole II (902) and a radial hole II (901) vertically penetrating the axial end hole II (902); The two ends of the ultra-high temperature test piece (8) are respectively inserted into the axial end hole I (602) of the connecting column I (6) and the axial end hole II (902) of the connecting column II (9), and the two ends of the ultra-high temperature test piece (8) are respectively provided with a left connecting hole (803) and a right connecting hole (804) along the radial direction, the left connecting hole (803) is connected to the radial hole I (601) through a tungsten-molybdenum alloy locking pin (7), and the right connecting hole (804) is connected to the radial hole II (901) through another tungsten-molybdenum alloy locking pin (7); The connecting column I (6), the connecting column II (9), the ultra-high temperature test piece (8) and the two tungsten-molybdenum alloy locking pins (7) are assembled by cold-installation thermal expansion interference connection; the connecting column I (6) and the connecting column II (9) are made of ultra-high temperature ceramics; The heating sleeve assembly comprises a reflective tube (10), a bracket (11), a water-cooled heating coil (12) and a graphite sleeve (13), wherein the graphite sleeve (13), the water-cooled heating coil (12) and the reflective tube (10) are coaxially sleeved in sequence from the inside to the outside, and the reflective tube (10) is fixed to the inner wall of the vacuum chamber (3) through the bracket (11); the ultra-high temperature test piece (8) passes through the inner cavity of the graphite sleeve (13); and the reflective tube (10) is used to reflect the heat radiation of the graphite sleeve (13) inwardly; The variable load mechanism comprises a spring I (305), a vibrator (306) and a spring II (307), wherein the vibrator (306) is slidably matched with the inner wall of the variable load chamber, the spring I (305) and the spring II (307) are respectively arranged on both sides of the vibrator (306), and one end of the spring I (305) and the spring II (307) are both connected to the vibrator (306), and the other ends of the spring I (305) and the spring II (307) are respectively connected to the vacuum chamber (3) and the connecting column II (9); The high temperature resistant metal material fatigue testing device further comprises a non-contact measuring mechanism (5), an observation window (304) is provided on the side wall of the vacuum chamber (3), and a measuring through hole is provided on the side wall of the heating sleeve assembly, and the detection light (16) emitted by the non-contact measuring mechanism (5) passes through the observation window (304) and the measuring through hole of the heating sleeve assembly and then irradiates the ultra-high temperature test piece (8).

2. The high temperature resistant metal material fatigue testing device according to claim 1, characterized in that: There is a radial gap between the inner walls at both ends of the reflective tube (10) and the connecting column I (6) and the connecting column II (9); the reflective tube (10) is made of ultra-high temperature ceramics.

3. The high temperature resistant metal material fatigue testing device according to claim 1, characterized in that: The water-cooled heating coil (12) is a hollow structure and contains a cold water channel inside.

4. The high temperature resistant metal material fatigue testing device according to claim 1, characterized in that: The vacuum chamber (3) comprises a cylinder (302) and a left cover (301) and a right cover (303) arranged at two ends of the cylinder (302); a drag chain mechanism (4) is provided on one side of the cylinder (302).

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