Training method for eliminating memory effect residual strain of shape memory alloy and application thereof

Abstract

The invention provides a training method for eliminating memory effect residual strain of shape memory alloy and application thereof, and the method comprises the following steps: 1) carrying out first direction loading on the shape memory alloy in an initial shaping state until the deformation quantity in the first direction reaches a first target value, and then carrying out first heating treatment and first cooling treatment until the deformation quantity in the first direction reaches a second target value; the shape memory alloy in the first state is obtained; 2) repeating the step 1) until the memory effect residual strain in the first direction reaches a constant value to obtain a second state memory alloy; (3) loading in a second direction until the deformation quantity in the second direction reaches a first target value, and then carrying out second heating treatment and second cooling treatment to obtain a third state memory alloy; the second direction is opposite to the first direction; and 4) repeating the step 3) until the memory alloy in the initial shaping state is obtained. According to the training method, it can be ensured that the application shape and the shaping shape of the shape memory alloy are consistent, and application of the shape memory alloy is facilitated.

Description

Technical Field

[0001] The invention relates to a training method for eliminating the memory effect residual strain of a shape memory alloy, in particular to a training method for eliminating the memory effect residual strain of a shape memory alloy and application thereof, belonging to the technical field of metal material processing. Background Art

[0002] Shape memory alloys have the shape memory effect, that is, they can deform at low temperatures and recover their shape after heating. Therefore, driving components made of shape memory alloys are widely used in aerospace, biomedicine and other fields.

[0003] However, the shape memory effect of shape memory alloys is often accompanied by residual strain problems, which results in residual strain in the fixed shape of the shape memory alloy after training, causing the shape memory alloy to change shape and unable to return to the fixed shape, which limits the application of shape memory alloys to a certain extent.

[0004] The usual solution is to reserve a certain amount of strain during shaping, and realize the mutual compensation of the residual strain and the reserved strain after the shape memory alloy is trained, so as to achieve the purpose of making the applied shape of the driving part consistent with the finalized shape in the application. However, during the heating recovery process after the shape memory alloy is deformed, the recoverable deformation is difficult to control, which can easily cause insufficient or excessive reserved strain, resulting in inconsistency between the applied shape and the finalized shape in the application.

[0005] Based on the above-mentioned deficiencies, those skilled in the art are in urgent need of developing a training process that can ensure that the application shape of the shape memory alloy is consistent with the final shape. Summary of the invention

[0006] The invention provides a training method for eliminating the memory effect residual strain of a shape memory alloy. The training method can ensure that the application shape of the shape memory alloy is consistent with the finalized shape, which is beneficial to the application of the shape memory alloy.

[0007] The invention provides a shape memory alloy with memory effect residual strain eliminated. The memory effect residual strain of the shape memory alloy has been eliminated, so that the shape memory alloy is prevented from having residual strain after training, which is beneficial to the application of the shape memory alloy.

[0008] The invention provides an application method of a shape memory alloy which eliminates the residual strain of the memory effect, so that the shape memory alloy can be reasonably deformed and the application range of the shape memory alloy is expanded.

[0009] The present invention provides a training method for eliminating the memory effect residual strain of a shape memory alloy, which comprises the following steps:

[0010] 1) loading the shape memory alloy in an initial shaping state in a first direction until the deformation amount of the shape memory alloy in the first direction reaches a first target value, and then performing a first heating treatment and a first cooling treatment on the shape memory alloy to obtain a shape memory alloy in a first state;

[0011] 2) Repeating step 1) for the shape memory alloy in the first state until the memory effect residual strain of the shape memory alloy in the first direction reaches a constant value, thereby obtaining the shape memory alloy in the second state;

[0012] 3) performing a second direction loading on the shape memory alloy in the second state until the deformation amount of the shape memory alloy in the second direction reaches a first target value, and then performing a second heating treatment and a second cooling treatment on the shape memory alloy to obtain a shape memory alloy in a third state;

[0013] wherein the second direction is opposite to the first direction;

[0014] 4) Repeat step 3) for the shape memory alloy in the third state until the shape memory alloy in the initial shaping state is obtained.

[0015] The training method for eliminating the memory effect residual strain of the shape memory alloy as described above, wherein the shape memory alloy in the initial shaping state is prepared by a method comprising the following steps:

[0016] After the shape memory alloy is molded, it is annealed to obtain the shape memory alloy in the initial molding state.

[0017] In the training method for eliminating the memory effect residual strain of shape memory alloy as described above, the first target value is no more than 8%.

[0018] The training method for eliminating the memory effect residual strain of the shape memory alloy as described above, wherein the first heating treatment and / or the second heating treatment comprises the following steps:

[0019] Heating the shape memory alloy to A°C;

[0020] Wherein, A≥the austenite transformation end temperature of the deformed shape memory alloy.

[0021] The training method for eliminating the memory effect residual strain of the shape memory alloy as described above, wherein the first cooling process and / or the second cooling process comprises the following steps:

[0022] Cooling the shape memory alloy to B°C;

[0023] Wherein, B≤the martensitic transformation end temperature of the shape memory alloy.

[0024] As described above, the training method for eliminating the memory effect residual strain of the shape memory alloy, wherein the shape memory alloy includes a rod-shaped memory alloy, and the first direction loading includes the following steps: subjecting the rod-shaped memory alloy to axial stretching / compression treatment; the second direction loading includes the following steps: subjecting the rod-shaped memory alloy to axial compression / stretching treatment.

[0025] The training method for eliminating the memory effect residual strain of the shape memory alloy as described above, wherein the shape memory alloy comprises a lath-shaped memory alloy, and the first direction loading comprises the following steps: bending the lath-shaped memory alloy in the first direction; and the second direction loading comprises the following steps: bending the lath-shaped memory alloy in the second direction;

[0026] The first direction and the second direction are directions perpendicular to a plane formed by the length and width of the strip-shaped memory alloy.

[0027] The training method for eliminating the memory effect residual strain of a shape memory alloy as described above, wherein the shape memory alloy includes at least one of a NiTi shape memory alloy, a NiTiNb shape memory alloy, and a NiTiV shape memory alloy.

[0028] The present invention provides a shape memory alloy with memory effect residual strain eliminated, wherein the shape memory alloy with memory effect residual strain eliminated is prepared by the training method for eliminating memory effect residual strain of the shape memory alloy as described above.

[0029] The present invention also provides an application method of a shape memory alloy with memory effect residual strain eliminated, wherein the shape memory alloy with memory effect residual strain eliminated as described above is deformed, and the deformation amount of the deformation treatment is not higher than the difference between the first target value and the constant value.

[0030] The present invention uses a training method for eliminating the memory effect residual strain of the shape memory alloy, which can compensate for the dislocation slip that inevitably occurs in the martensite detwinning of the shape memory alloy after loading, thereby achieving the effect that the application shape of the shape memory alloy is consistent with the final shape. In addition, the training method is simple and efficient, and has low equipment requirements.

[0031] The present invention provides a shape memory alloy which eliminates the residual strain of the memory effect. The positive and reverse dislocation slips in the shape memory alloy can compensate each other, so that the shape memory alloy can be reasonably deformed within a certain degree without the residual strain of the memory effect, thereby enabling the shape memory alloy to be widely used.

[0032] The present invention also provides an application method of a shape memory alloy that eliminates residual strain due to memory effect. When the deformation amount of the deformation treatment is not higher than the difference between the first target value and the constant value, the shape memory alloy that eliminates residual strain due to memory effect is loaded in the first direction or the second direction, and then subjected to the first heating treatment and the first cooling treatment, the shape memory alloy can be completely restored to the initial shaping state, thereby ensuring the reasonable deformation of the shape memory alloy during the application process and avoiding the influence of residual strain on the shape memory alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Flowchart of the training method for eliminating the residual strain of the memory effect of shape memory alloy. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention provides a training method for eliminating the memory effect residual strain of a shape memory alloy, comprising the following steps:

[0036] 1) loading the shape memory alloy in an initial shaping state in a first direction until the deformation amount of the shape memory alloy in the first direction reaches a first target value, and then performing a first heating treatment and a first cooling treatment on the shape memory alloy to obtain the shape memory alloy in a first state;

[0037] 2) Repeating step 1) for the shape memory alloy in the first state until the memory effect residual strain of the shape memory alloy in the first direction reaches a constant value, thereby obtaining the shape memory alloy in the second state;

[0038] 3) performing a second direction loading on the shape memory alloy in the second state until the deformation amount of the shape memory alloy in the second direction reaches a first target value, and then performing a second heating treatment and a second cooling treatment on the shape memory alloy to obtain a shape memory alloy in a third state;

[0039] wherein the second direction is opposite to the first direction;

[0040] 4) Repeat step 3) for the shape memory alloy in the third state until the shape memory alloy in the initial shaping state is obtained.

[0041] Specifically, Figure 1As shown, step 1), the shape memory alloy in the initial shaping state is subjected to a loading treatment in the first direction, and the shape memory alloy in the initial shaping state is deformed in the first direction, and the shape memory alloy is continuously loaded in the first direction until the deformation in the first direction reaches the first target value, and the loading in the first direction stops, at which time the deformation of the shape memory alloy is the first target value in the first direction; then the shape memory alloy with the deformation of the first target value is subjected to a first heating treatment and a first cooling treatment, so that the shape memory alloy recovers its shape, and a shape memory alloy in the first state is obtained. Since the shape memory alloy has a memory effect residual strain, the shape memory alloy in the first state has a certain amount of residual strain in the first direction.

[0042] The shape memory alloy of the present invention refers to a material composed of two or more metal elements that has a shape memory effect through thermoelasticity and martensitic phase transformation and its inversion. The present invention does not limit the specific selection of the shape memory alloy, as long as it has a memory effect.

[0043] The calculation method of the deformation amount of the present invention varies according to the different deformation modes. For example, the axial deformation is calculated by axial elongation and compression, while the bending deformation is calculated by measuring the maximum distance that the neutral line of the sample deviates from the original position under the bending action, refer to GB / T 14452-93.

[0044] The present invention does not limit the specific selection of the first target value, which can be determined according to the type and application scenario of the shape memory alloy.

[0045] The present invention does not limit the specific parameters of the first heating treatment and the first cooling treatment, as long as the shape memory alloy can recover its deformation.

[0046] Step 2), loading the shape memory alloy in the first state in a first direction until the deformation in the first direction reaches a first target value, then performing a first heating treatment and a first cooling treatment, and after repeating step 1), the residual strain of the shape memory alloy in the first direction increases, and step 1 is continued to be repeated until the residual strain of the shape memory alloy in the first direction no longer increases and reaches a constant value, thereby obtaining a shape memory alloy in the second state.

[0047] Compared with shape memory alloys in other states, the residual strain of the shape memory alloy in the second state of the present invention is the largest.

[0048] The first target value in step 2) is calculated based on the shape memory alloy in an initial state.

[0049] Step 3), the shape memory alloy in the second state is loaded in a second direction, which is opposite to the first direction, and the shape memory alloy is continuously loaded in the second direction until the deformation in the second direction reaches the first target value, and the loading in the second direction stops. At this time, the deformation of the shape memory alloy is the first target value in the second direction, and then the shape memory alloy is subjected to a second heating treatment and a second cooling treatment to restore the shape of the shape memory alloy to obtain a shape memory alloy in a third state.

[0050] The training in the second direction can compensate for the residual strain in the first direction. Therefore, compared with the shape memory alloy in the second state, the shape memory alloy in the third state has a smaller residual strain in the first direction.

[0051] The second direction of the present invention is opposite to the first direction, which means that the first direction and the second direction are on the same straight line, and the first direction and the second direction move in opposite directions.

[0052] The present invention does not limit the specific parameters of the second heating treatment and the second cooling treatment, as long as the shape memory alloy can recover its deformation.

[0053] It is worth noting that the force loaded in the first direction and the force loaded in the second direction can be the same or different, as long as the deformation amount loaded in the first direction and the deformation amount loaded in the second direction both reach the first target value.

[0054] Step 4), repeating step 3) for the shape memory alloy in the third state, the residual strain in the first direction of the shape memory alloy will become smaller and smaller until it is 0, thereby obtaining the shape memory alloy in the initial shaping state.

[0055] The present invention uses a training method to eliminate the memory effect residual strain of the shape memory alloy, which can compensate for the dislocation slip that inevitably occurs in the martensite detwinning after loading, thereby achieving the effect that the application shape of the shape memory alloy is consistent with the final shape. In addition, the training method is simple and efficient, and has low equipment requirements.

[0056] In a specific embodiment, the shape memory alloy in the initial shaped state is prepared by a method comprising the following steps:

[0057] After the shape memory alloy is molded, it is annealed to obtain the shape memory alloy in an initial molding state.

[0058] Specifically, first, a shape memory alloy is shaped using a mold according to a target shape to obtain a shape memory alloy with a target shape. However, the shape memory alloy will change in shape over time. In order to remove the stress inside the shape memory alloy, the shape memory alloy is annealed to finally obtain a shape memory alloy in an initial shaped state, which can maintain the target shape.

[0059] The present invention does not limit the specific operation of mold shaping, which can be selected according to the specific application. For example, the shape memory alloy can be subjected to a pressing process or a stretching process.

[0060] The present invention does not limit the specific parameters of the annealing treatment. The specific parameters of the annealing treatment are selected according to the type of the shape memory alloy, as long as the internal stress of the shape memory alloy can be removed.

[0061] The present invention can prepare a shape memory alloy with an initial shaping state through the method, and can adjust the initial shaping state of the shape memory alloy according to actual applications, which is beneficial to the wide application of the shape memory alloy.

[0062] In a specific embodiment, the first target value is not greater than 8%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%, etc. When the first target value is within the above range, the shape memory alloy can recover the deformation through training, avoiding a large number of dislocation slips inside the shape memory alloy, which causes the shape memory alloy to be unable to recover the deformation, thereby facilitating the elimination of the residual strain of the memory effect, and further expanding the application of the shape memory alloy.

[0063] In a specific embodiment, the first heating treatment and / or the second heating treatment comprises the following steps:

[0064] The shape memory alloy is heated to A°C; wherein A≥the austenite transformation end temperature of the deformed shape memory alloy.

[0065] The austenite transformation end temperature of the deformed shape memory alloy of the present invention is different from the austenite transformation end temperature of the undeformed shape memory alloy, and the austenite transformation end temperature is related to the selection of the shape memory alloy. The present invention does not limit the specific selection of the heating rate, which can be selected according to actual needs. The austenite transformation end temperature of the deformed shape memory alloy of the present invention can be obtained by DSC testing.

[0066] The heating rates of the first heating treatment and the second heating treatment of the present invention may be the same or different, and are selected according to actual needs.

[0067] During the first heating treatment and the second heating treatment of the present invention, the deformation of the shape memory alloy will recover as the temperature rises, and the oriented martensite gradually absorbs heat to undergo a parent phase transformation and transforms into austenite until A℃, and the deformation of the shape memory alloy ends, which is conducive to efficiently completing the training of eliminating the memory effect residual strain of the shape memory alloy.

[0068] In a specific embodiment, the first cooling process and / or the second cooling process comprises the following steps:

[0069] The shape memory alloy is cooled to B°C, wherein B≤the martensitic transformation end temperature of the shape memory alloy.

[0070] The martensitic phase transition temperature of the shape memory alloy of the present invention is related to the selection of the shape memory alloy, and is selected according to the type of the shape memory alloy. The martensitic phase transition temperature of the shape memory alloy of the present invention can be obtained by DSC testing.

[0071] The cooling rates of the first cooling process and the second cooling process of the present invention may be the same or different, and are selected according to actual needs.

[0072] The first cooling treatment and the second cooling treatment of the present invention can cause the shape memory alloy to gradually release heat from the parent phase to undergo a martensitic phase transformation, thereby completing the training of eliminating the memory effect residual strain of the shape memory alloy.

[0073] In a specific embodiment, the shape memory alloy includes a rod-shaped memory alloy, and loading in the first direction includes the following steps: subjecting the rod-shaped memory alloy to axial stretching / compression; and loading in the second direction includes the following steps: subjecting the rod-shaped memory alloy to axial compression / stretching.

[0074] When the shape memory alloy is a rod-shaped memory alloy and the memory effect is required to be an axial memory effect, the rod-shaped memory alloy is subjected to axial stretching or compression, and then the rod-shaped memory alloy is subjected to corresponding axial compression or stretching.

[0075] The rod-shaped memory alloy of the present invention refers to a memory alloy having a cylindrical shape.

[0076] The axial processing of the present invention refers to the direction of the central axis of the cylindrical body of the cylindrical memory alloy.

[0077] The first direction and the second direction of the present invention have opposite loading directions.

[0078] The present invention performs the first direction processing and the second direction processing on the rod-shaped memory alloy, which can ensure the elimination of the residual strain of the memory effect of the rod-shaped memory alloy in the axial direction, so that the rod-shaped memory alloy can be reasonably deformed in the axial direction, which is beneficial to the reasonable application of the rod-shaped memory alloy.

[0079] Specifically, the deformation amount of the stretching or compression treatment of the present invention can be tested by a universal testing machine, so as to control the deformation amount of the stretching or compression treatment to be consistent.

[0080] In a specific embodiment, the shape memory alloy includes a strip-shaped memory alloy, and the first direction loading includes the following steps: bending the strip-shaped memory alloy in the first direction; the second direction loading includes the following steps: bending the strip-shaped memory alloy in the second direction;

[0081] The first direction and the second direction are directions perpendicular to a plane formed by the length and width of the strip-shaped memory alloy.

[0082] When the shape memory alloy is a strip-shaped memory alloy and the memory effect is required to be in a direction perpendicular to the plane formed by the length and width of the strip-shaped memory alloy, the strip-shaped memory alloy is bent in a first direction and then bent in a second direction, and the first direction is opposite to the second direction.

[0083] The strip-shaped memory alloy of the present invention refers to a strip-shaped memory alloy whose length is much greater than its thickness.

[0084] The direction perpendicular to the plane formed by the length and width of the strip-shaped memory alloy in the present invention refers to the direction parallel to the thickness of the strip-shaped memory alloy.

[0085] The present invention performs bending processing on the lath-shaped memory alloy in the first direction and the second direction, which can eliminate the memory effect residual strain of the lath-shaped memory alloy in the thickness direction, so that the lath-shaped memory alloy can ensure reasonable bending deformation, thereby expanding the application of the lath-shaped memory alloy.

[0086] In a specific embodiment, the shape memory alloy includes at least one of NiTi shape memory alloy, NiTiNb shape memory alloy, and NiTiV shape memory alloy. When the shape memory alloy is selected from the above materials, the shape memory alloy includes the advantages of high expansion and contraction rate, long fatigue life, high damping characteristics, excellent corrosion resistance, shape memory function, wear resistance, corrosion resistance, high damping and superelasticity. Through the training method provided by the present invention, NiTi shape memory alloys with no memory effect residual strain can be prepared, thereby expanding the application of shape memory alloys of materials such as NiTi in aerospace, biomedicine and other fields.

[0087] The present invention provides a shape memory alloy with memory effect residual strain eliminated, and the shape memory alloy with memory effect residual strain eliminated is prepared by the above-mentioned training method for eliminating the memory effect residual strain of the shape memory alloy. The present invention cancels out the positive and negative residual strains in the shape memory alloy by the above-mentioned training method, so that the shape memory alloy can be reasonably deformed within a certain degree without memory effect residual strain, thereby enabling the shape memory alloy to be widely used.

[0088] The present invention also provides an application method of a shape memory alloy with memory effect residual strain eliminated, wherein the shape memory alloy with memory effect residual strain eliminated is subjected to deformation treatment, and the deformation amount of the deformation treatment is not higher than the difference between the first target value and the constant value. When the deformation amount of the deformation treatment is not higher than the difference between the first target value and the constant value, after the shape memory alloy with memory effect residual strain eliminated is loaded in the first direction or the second direction, and after the first heating treatment and the first cooling treatment are performed, the shape memory alloy can be completely restored to the initial shaping state, thereby ensuring the reasonable deformation of the shape memory alloy during the application process and avoiding the influence of the residual strain on the shape memory alloy.

[0089] Hereinafter, the present invention will be further described in detail through specific examples.

[0090] Example 1

[0091] The preparation process of the shape memory alloy with the memory effect residual strain eliminated provided in this embodiment comprises the following steps:

[0092] 1. The NiTi shape memory alloy is shaped into a rod through a mold and treated at 450°C for 10 minutes to obtain a NiTi rod-shaped memory alloy in an initial shaped state;

[0093] 2. The NiTi rod-shaped memory alloy is stretched in the axial direction until the deformation of the NiTi rod-shaped memory alloy in the stretching direction reaches 8%, and then the NiTi rod-shaped memory alloy is heated to 95° C., and then the NiTi rod-shaped memory alloy is cooled to 10° C. to obtain the NiTi rod-shaped memory alloy in the first state;

[0094] Among them, the DSC test of the deformed NiTi rod-shaped memory alloy shows that the austenite transformation end temperature of the deformed NiTi rod-shaped memory alloy is 95°C; the DSC test of the NiTi rod-shaped memory alloy shows that the martensite phase transition temperature of the NiTi rod-shaped memory alloy is 10°C;

[0095] 3. Repeat step 2) until the memory effect residual strain of the NiTi rod-shaped memory alloy in the tensile direction reaches a constant value (the constant value is 2%), and obtain the NiTi rod-shaped memory alloy in the second state;

[0096] 4. The NiTi rod-shaped memory alloy in the second state is compressed until the deformation of the NiTi rod-shaped memory alloy in the compression direction reaches 8%, and then the NiTi rod-shaped memory alloy is heated to 95° C., and then the NiTi rod-shaped memory alloy is cooled to 10° C. to obtain the NiTi rod-shaped memory alloy in the third state;

[0097] 5. Repeat step 4) until the memory effect residual strain of the NiTi rod-shaped memory alloy in the tensile direction is 0, thereby obtaining the NiTi rod-shaped memory alloy in the initial shaping state.

[0098] 6. The trained NiTi rod-shaped memory alloy is compressed to a deformation within 6%, and then the NiTi rod-shaped memory alloy is heated to 95° C., and then the NiTi rod-shaped memory alloy is cooled to 10° C. to obtain a NiTi rod-shaped memory alloy with fully recovered deformation.

[0099] Example 2

[0100] The preparation process of the shape memory alloy with the memory effect residual strain eliminated provided in this embodiment comprises the following steps:

[0101] 1. The NiTi shape memory alloy is shaped into a lath shape by a mold, and treated at 450° C. for 10 min to obtain the NiTi lath shape memory alloy in the initial shaped state;

[0102] 2. The NiTi lath-shaped memory alloy is bent in a direction perpendicular to the plane formed by the length and width of the lath until the deformation of the NiTi lath-shaped memory alloy in the first direction reaches 8%, and then the NiTi lath-shaped memory alloy is heated to 95° C., and then the NiTi lath-shaped memory alloy is cooled to 10° C. to obtain the NiTi lath-shaped memory alloy in the first state;

[0103] Among them, the DSC test of the deformed NiTi lath memory alloy was carried out, and the austenite transformation end temperature of the deformed NiTi lath memory alloy was obtained to be 95°C; the DSC test of the NiTi lath memory alloy was carried out, and the martensite phase transition temperature of the NiTi lath memory alloy was obtained to be 10°C;

[0104] 3. Repeat step 2) until the memory effect residual strain of the NiTi lath-shaped memory alloy in the first direction reaches a constant value (the constant value is 2%), and obtain the NiTi lath-shaped memory alloy in the second state;

[0105] 4. The NiTi lath-shaped memory alloy in the second state is bent in the second direction until the deformation of the NiTi lath-shaped memory alloy in the second direction reaches 8%, and then the NiTi lath-shaped memory alloy is heated to 95° C., and then the NiTi lath-shaped memory alloy is cooled to 10° C. to obtain the NiTi lath-shaped memory alloy in the third state;

[0106] wherein the second direction is opposite to the first direction;

[0107] 5. Repeat step 4) until the memory effect residual strain of the NiTi lath-shaped memory alloy in the first direction is 0, thereby obtaining the NiTi lath-shaped memory alloy in an initial shaping state.

[0108] 6. The trained NiTi lath-shaped memory alloy is subjected to compression treatment and deformation treatment in the second direction, with a deformation amount of 6%. The NiTi lath-shaped memory alloy is then heated to 95° C., and then cooled to 10° C. to obtain a NiTi lath-shaped memory alloy with completely recovered deformation.

[0109] Example 3

[0110] The preparation process of the shape memory alloy with the memory effect residual strain eliminated provided in this embodiment comprises the following steps:

[0111] 1. The NiTi shape memory alloy is shaped into a lath shape by a mold, and treated at 450° C. for 10 min to obtain the NiTi lath shape memory alloy in the initial shaped state;

[0112] 2. The NiTi lath-shaped memory alloy is bent in a direction perpendicular to the plane formed by the length and width of the lath until the deformation of the NiTi lath-shaped memory alloy in the first direction reaches 6%, and then the NiTi lath-shaped memory alloy is heated to 90° C., and then the NiTi lath-shaped memory alloy is cooled to 10° C. to obtain the NiTi lath-shaped memory alloy in the first state;

[0113] Among them, the DSC test of the deformed NiTi lath memory alloy was carried out, and the austenite transformation end temperature of the deformed NiTi lath memory alloy was obtained to be 90°C; the DSC test of the NiTi lath memory alloy was carried out, and the martensite phase transition temperature of the NiTi lath memory alloy was obtained to be 10°C;

[0114] 3. Repeat step 2) until the memory effect residual strain of the NiTi lath-shaped memory alloy in the first direction reaches a constant value (the constant value is 1.6%), and obtain the NiTi lath-shaped memory alloy in the second state;

[0115] 4. The NiTi lath-shaped memory alloy in the second state is bent in the second direction until the deformation of the NiTi lath-shaped memory alloy in the second direction reaches 6%, and then the NiTi lath-shaped memory alloy is heated to 90° C., and then the NiTi lath-shaped memory alloy is cooled to 10° C. to obtain the NiTi lath-shaped memory alloy in the third state;

[0116] wherein the second direction is opposite to the first direction;

[0117] 5. Repeat step 4) until the memory effect residual strain of the NiTi lath-shaped memory alloy in the first direction is 0, thereby obtaining the NiTi lath-shaped memory alloy in an initial shaping state.

[0118] 6. The trained NiTi lath-shaped memory alloy is subjected to a second direction deformation treatment with a deformation amount of 4.4%. The NiTi lath-shaped memory alloy is then heated to 90° C. and then cooled to 10° C. to obtain a NiTi lath-shaped memory alloy with fully recovered deformation.

[0119] Example 4

[0120] The preparation process of the shape memory alloy with the memory effect residual strain eliminated provided in this embodiment comprises the following steps:

[0121] 1. The NiTi shape memory alloy is shaped into a lath shape by a mold, and treated at 450° C. for 10 min to obtain the NiTi lath shape memory alloy in the initial shaped state;

[0122] 2. The NiTi lath-shaped memory alloy is bent in a direction perpendicular to the plane formed by the length and width of the lath until the deformation of the NiTi lath-shaped memory alloy in the first direction reaches 4%, and then the NiTi lath-shaped memory alloy is heated to 80° C., and then the NiTi lath-shaped memory alloy is cooled to 10° C. to obtain the NiTi lath-shaped memory alloy in the first state;

[0123] Among them, the DSC test of the deformed NiTi lath memory alloy shows that the austenite transformation end temperature of the deformed NiTi lath memory alloy is 80°C; the DSC test of the NiTi lath memory alloy shows that the martensite phase transition temperature of the NiTi lath memory alloy is 10°C;

[0124] 3. Repeat step 2) until the memory effect residual strain of the NiTi lath-shaped memory alloy in the first direction reaches a constant value (the constant value is 1.3%), and obtain the NiTi lath-shaped memory alloy in the second state;

[0125] 4. The NiTi lath-shaped memory alloy in the second state is bent in the second direction until the deformation of the NiTi lath-shaped memory alloy in the second direction reaches 4%, and then the NiTi lath-shaped memory alloy is heated to 80° C., and then the NiTi lath-shaped memory alloy is cooled to 10° C. to obtain the NiTi lath-shaped memory alloy in the third state;

[0126] wherein the second direction is opposite to the first direction;

[0127] 5. Repeat step 4) until the memory effect residual strain of the NiTi lath-shaped memory alloy in the first direction is 0, thereby obtaining the NiTi lath-shaped memory alloy in an initial shaping state.

[0128] 6. The trained NiTi lath-shaped memory alloy is subjected to a second direction deformation treatment with a deformation amount of 2.7%. The NiTi lath-shaped memory alloy is then heated to 80° C. and then cooled to 10° C. to obtain a NiTi lath-shaped memory alloy with fully recovered deformation.

[0129] Example 7

[0130] The preparation process of the shape memory alloy with the memory effect residual strain eliminated provided in this embodiment comprises the following steps:

[0131] 1. The NiTiNb shape memory alloy is formed into a lath shape by a mold, and treated at 650°C for 10 minutes to obtain a NiTiNb lath shape memory alloy in an initial forming state;

[0132] 2. The NiTiNb lath-shaped memory alloy is bent in a direction perpendicular to the plane formed by the length and width of the lath in its martensitic state until the deformation of the NiTiNb lath-shaped memory alloy in the first direction reaches 8%, and then the NiTiNb lath-shaped memory alloy is heated to 70° C., and then the NiTiNb lath-shaped memory alloy is cooled to −60° C. to obtain the NiTiNb lath-shaped memory alloy in the first state;

[0133] Among them, the DSC test of the deformed NiTiNb lath memory alloy was carried out, and the austenite transformation end temperature of the deformed NiTiNb lath memory alloy was 70°C; the DSC test of the NiTiNb lath memory alloy was carried out, and the martensite phase transition temperature of the NiTiNb lath memory alloy was -60°C;

[0134] 3. Repeat step 2) until the memory effect residual strain of the NiTiNb lath-shaped memory alloy in the first direction reaches a constant value (the constant value is 1.2%), and obtain the NiTiNb lath-shaped memory alloy in the second state;

[0135] 4. The NiTiNb lath-shaped memory alloy in the second state is bent in the second direction until the deformation of the NiTiNb lath-shaped memory alloy in the second direction reaches 8%, and then the NiTiNb lath-shaped memory alloy is heated to 70° C., and then the NiTiNb lath-shaped memory alloy is cooled to below -60° C. to obtain the NiTiNb lath-shaped memory alloy in the third state;

[0136] wherein the second direction is opposite to the first direction;

[0137] 5. Repeat step 4) until the memory effect residual strain of the NiTiNb lath-shaped memory alloy in the first direction is 0, thereby obtaining the NiTiNb lath-shaped memory alloy in an initial shaping state.

[0138] 6. The trained NiTiNb lath-shaped memory alloy is subjected to a second direction deformation treatment with a deformation amount of 6.8%. The NiTiNb lath-shaped memory alloy is then heated to 70°C and then cooled to -60°C to obtain a NiTiNb lath-shaped memory alloy with fully recovered deformation.

[0139] Comparative Example 1

[0140] The preparation process of the shape memory alloy provided in this comparative example comprises the following steps:

[0141] 1. The NiTi shape memory alloy is shaped into a lath shape by a mold, and treated at 450° C. for 10 min to obtain the NiTi lath shape memory alloy in the initial shaped state;

[0142] 2. The NiTi lath-shaped memory alloy is bent in a direction perpendicular to the plane formed by the length and width of the lath until the deformation of the NiTi lath-shaped memory alloy in the first direction reaches 8%, and then the NiTi lath-shaped memory alloy is heated to 95° C., and then the NiTi lath-shaped memory alloy is cooled to below 10° C. to obtain the NiTi lath-shaped memory alloy;

[0143] Among them, the DSC test was performed on the deformed NiTi lath memory alloy, and the austenite transformation end temperature of the deformed NiTi lath memory alloy was obtained to be 95°C; the DSC test was performed on the NiTi lath memory alloy, and the martensite phase transition temperature of the NiTi lath memory alloy was obtained to be 10°C.

[0144] 3. The trained NiTi lath-shaped memory alloy is bent in the first direction with a deformation amount of 8% (this deformation amount includes the above-mentioned training residual deformation), and then the NiTi lath-shaped memory alloy is heated to 95°C, and then the NiTi lath-shaped memory alloy is cooled to 10°C to obtain a NiTi lath-shaped memory alloy; the memory effect residual strain of the NiTi lath-shaped memory alloy is 2%.

[0145] In summary, the training method for eliminating the memory effect residual strain of the shape memory alloy provided by the present invention can train the shape memory alloy to ensure that the application shape of the shape memory alloy is consistent with the final shape, thereby expanding the application of the shape memory alloy.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A training method for eliminating the memory effect residual strain of shape memory alloy, characterized in that: The following steps are involved: 1) loading the shape memory alloy in an initial shaping state in a first direction until the deformation amount of the shape memory alloy in the first direction reaches a first target value, and then performing a first heating treatment and a first cooling treatment on the shape memory alloy to obtain a shape memory alloy in a first state; 2) Repeating step 1) for the shape memory alloy in the first state until the memory effect residual strain of the shape memory alloy in the first direction reaches a constant value, thereby obtaining the shape memory alloy in the second state; 3) performing a second direction loading on the shape memory alloy in the second state until the deformation amount of the shape memory alloy in the second direction reaches a first target value, and then performing a second heating treatment and a second cooling treatment on the shape memory alloy to obtain a shape memory alloy in a third state; wherein the second direction is opposite to the first direction; 4) Repeat step 3) for the shape memory alloy in the third state until the shape memory alloy in the initial shaping state is obtained.

2. The training method for eliminating the memory effect residual strain of shape memory alloy according to claim 1, characterized in that: The shape memory alloy in the initial shaping state is prepared by a method comprising the following steps: After the shape memory alloy is molded, it is annealed to obtain the shape memory alloy in the initial molding state.

3. The training method for eliminating the memory effect residual strain of shape memory alloy according to claim 1 or 2, characterized in that: The first target value is no greater than 8%.

4. The training method for eliminating the memory effect residual strain of shape memory alloy according to any one of claims 1 to 3, characterized in that: The first heating treatment and / or the second heating treatment comprises the following steps: Heating the shape memory alloy to A°C; Wherein, A≥the austenite transformation end temperature of the deformed shape memory alloy.

5. The training method for eliminating the memory effect residual strain of shape memory alloy according to any one of claims 1 to 4, characterized in that: The first cooling process and / or the second cooling process comprises the following steps: Cooling the shape memory alloy to B°C; Wherein, B≤the martensitic transformation end temperature of the shape memory alloy.

6. The training method for eliminating the memory effect residual strain of shape memory alloy according to any one of claims 1 to 5, characterized in that: The shape memory alloy comprises a rod-shaped memory alloy, and the first direction loading comprises the following steps: subjecting the rod-shaped memory alloy to axial stretching / compression; and the second direction loading comprises the following steps: subjecting the rod-shaped memory alloy to axial compression / stretching.

7. The training method for eliminating the memory effect residual strain of shape memory alloy according to any one of claims 1 to 5, characterized in that: The shape memory alloy includes a strip-shaped memory alloy, and the first direction loading includes the following steps: bending the strip-shaped memory alloy in the first direction; the second direction loading includes the following steps: bending the strip-shaped memory alloy in the second direction; The first direction and the second direction are directions perpendicular to a plane formed by the length and width of the strip-shaped memory alloy.

8. The training method for eliminating the memory effect residual strain of shape memory alloy according to any one of claims 1 to 7, characterized in that: The shape memory alloy includes at least one of NiTi shape memory alloy, NiTiNb shape memory alloy and NiTiV shape memory alloy.

9. A shape memory alloy that eliminates the residual strain of the memory effect, characterized in that: The shape memory alloy with the memory effect residual strain eliminated is prepared by the training method for eliminating the memory effect residual strain of the shape memory alloy according to any one of claims 1 to 8.

10. An application method of a shape memory alloy that eliminates residual strain of memory effect, characterized in that: The shape memory alloy with the residual strain of memory effect eliminated as claimed in claim 9 is subjected to deformation treatment, and the deformation amount of the deformation treatment is not higher than the difference between the first target value and the constant value.

Images