Method for preparing FeMnSi alloy with remarkable low-temperature shape memory effect through 3D printing

Abstract

The invention discloses a method for preparing a FeMnSi alloy with a remarkable low-temperature shape memory effect through 3D printing, and the method comprises the following steps: 1, carrying out room-temperature rotary mixing on powder containing FeMnCrNiSi element components to obtain mixed powder; and secondly, the mixed powder serves as a raw material, and a metal powder bed selective laser melting 3D printing technology is adopted for preparing the block FeMnSi series alloy. By developing FeMnSi system alloy components with the characteristics of high Cr content, high Ni content and middle Si content, the stacking fault energy is effectively reduced, the defects of stacking fault, dislocation and the like in the FeMnSi system alloy are greatly improved, martensite phase transformation in the deformation process is promoted, and therefore good 3D printing process adaptability is achieved, the cracking risk is reduced, and the service life of the product is prolonged. And the material has obvious shape memory effect and tensile strength at low temperature, and is suitable for reusable impact-resistant, load-bearing and functional devices in polar space environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and specifically relates to a method for preparing a FeMnSi alloy having a significant low-temperature shape memory effect by 3D printing. Background Art

[0002] FeMnSi shape memory alloys are generally composed of Fe, Mn, Cr, Ni, and Si elements, and have a significant shape memory effect. The mechanism is the fcc-hcp phase transition caused by deformation and the reverse phase transition of hcp-fcc after heating, which can eventually cause the deformed shape to recover to the initial shape. When the pre-strain of bending at room temperature is 5%, the recoverable strain can reach 2.5% to 3% after heating. At the same time, its low-temperature strength is much higher than that of NiTi shape memory alloys. Therefore, it is expected to be used as a reusable intelligent load-bearing, energy storage, and buffering element in a low-temperature environment in aerospace, robotics, and other fields. Since intelligent load-bearing, energy storage, and buffering elements usually need to have complex geometric shapes or porous structures, it is difficult to prepare such elements by conventional casting and rolling processes. Therefore, it is necessary to use metal powder bed selective laser melting 3D printing (Selective Laser Melting, SLM) with a large degree of manufacturing freedom to manufacture FeMnSi shape memory alloy intelligent load-bearing, energy storage, and buffering elements with complex structures. Since the 3D printing process has the characteristics of rapid cooling and cyclic heating during printing, there are a large number of defects such as dislocations inside the matrix, and the grain size is small. Therefore, the FeMnSi shape memory alloy formula suitable for traditional rolling and casting processes is difficult to obtain a good shape memory effect under the 3D printing process. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing FeMnSi alloys with significant low-temperature shape memory effect by 3D printing in view of the deficiencies of the above-mentioned prior art. The method effectively reduces the stacking fault energy and greatly improves the defects such as stacking faults and dislocations inside the FeMnSi alloy by developing FeMnSi alloy components with high Cr content, high Ni content and medium Si content, which is beneficial to promote the martensitic phase transformation during the deformation process, thereby having good adaptability to 3D printing processes, and having significant shape memory effect and tensile strength at low temperatures, solving the problem that the existing FeMnSi shape memory alloys are difficult to obtain good shape memory effect under 3D printing processes.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a FeMnSi alloy having a significant low-temperature shape memory effect by 3D printing, characterized in that the method comprises the following steps:

[0005] Step 1, rotating and mixing powder containing FeMnCrNiSi elemental components at room temperature to obtain mixed powder;

[0006] Step 2: Using the mixed powder obtained in step 1 as raw material, a bulk FeMnSi alloy is prepared by a metal powder bed selective laser melting 3D printing process.

[0007] The above-mentioned method for preparing a FeMnSi alloy with a significant low-temperature shape memory effect by 3D printing is characterized in that, in the powder containing the FeMnCrNiSi elemental components described in step one, the mass percentage of Mn is 16%, the mass percentage of Cr is 8% to 11%, the mass percentage of Ni is 6%, the mass percentage of Si is 5% to 5.5%, and the remainder is Fe.

[0008] The above-mentioned method for preparing FeMnSi alloy with significant low-temperature shape memory effect by 3D printing is characterized in that the laser line energy input of the metal powder bed selective laser melting 3D printing process in step 2 is above 0.35 J / mm. By controlling the laser line energy input, the high melting point Cr powder component in the mixed powder is ensured to melt.

[0009] The above-mentioned method for preparing a FeMnSi alloy with significant low-temperature shape memory effect by 3D printing is characterized in that a metal wire with a diameter of 1 mm is cut from the bulk FeMnSi alloy obtained in step 2 to perform a shape memory effect test.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] 1. Aiming at the high cooling rate and cyclic heating characteristics in the 3D printing process, the present invention develops a FeMnSi alloy composition with high Cr content, high Ni content and medium Si content. This composition effectively reduces the stacking fault energy and greatly improves the defects such as stacking faults and dislocations inside the FeMnSi alloy, which is beneficial to promote the martensitic phase transformation during the deformation process, so that a higher shape memory effect can be obtained without special pre-deformation treatment such as traditional processes.

[0012] 2. The FeMnSi alloy composition of the present invention has good adaptability to 3D printing processes, and has significant shape memory effect and tensile strength at low temperatures, and is suitable for reusable impact-resistant, load-bearing and functional devices in polar space environments.

[0013] 3. The present invention reduces the brittleness of the alloy matrix by reducing the Si content in the FeMnSi alloy composition, eliminates the risk of cracking of the printed part, i.e., the FeMnSi alloy, during the 3D printing process, while maintaining the low stacking fault energy of the printed part, further reducing the adverse effects on the shape memory effect of the FeMnSi alloy.

[0014] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0015] Example 1

[0016] This embodiment includes the following steps:

[0017] Step 1, rotating and mixing the powder containing the FeMnCrNiSi elemental component at room temperature to obtain a mixed powder; in the powder containing the FeMnCrNiSi elemental component, the mass percentage of Mn is 16%, the mass percentage of Cr is 11%, the mass percentage of Ni is 6%, the mass percentage of Si is 5.5%, and the balance is Fe;

[0018] Step 2: Using the mixed powder obtained in step 1 as raw material, a metal powder bed selective laser melting 3D printing process is adopted with a laser scanning speed of 900 mm / s, a laser power of 315 W, and a laser line energy input of 0.35 J / mm to prepare a FeMnSi alloy block with a size of 100 mm×10 mm×10 mm.

[0019] A metal wire with a diameter of 1 mm was cut from the FeMnSi alloy block prepared in this embodiment for shape memory effect test. The test method was based on "YS / T 1307.2-2019 Test Method for Memory Performance of Nickel-Titanium Shape Memory Alloy Part 2: Bending Test Method". The test temperature was 77K (the metal wire was bent by immersing it in liquid nitrogen to ensure the temperature). The shape memory effect data are shown in Table 1.

[0020] Table 1

[0021] Pre-strain (%) Recoverable strain (%) Shape recovery rate (%) 3.51 3.28 93 4.15 3.79 91 5.54 4.87 88 7.80 5.70 73 8.54 6.01 70 9.76 5.56 57

[0022] It can be seen from Table 1 that the bulk FeMnSi alloy prepared in this embodiment has a significant low-temperature shape memory effect, indicating that the present invention uses a FeMnSi alloy composition characterized by high Cr content, high Ni content, and medium Si content for metal powder bed selective laser melting 3D printing, which has good adaptability to 3D printing processes and has significant shape memory effect and tensile strength at low temperatures.

[0023] Example 2

[0024] This embodiment includes the following steps:

[0025] Step 1, rotating and mixing the powder containing the FeMnCrNiSi elemental component at room temperature to obtain a mixed powder; in the powder containing the FeMnCrNiSi elemental component, the mass percentage of Mn is 16%, the mass percentage of Cr is 8%, the mass percentage of Ni is 6%, the mass percentage of Si is 5.5%, and the balance is Fe;

[0026] Step 2: Using the mixed powder obtained in step 1 as raw material, a metal powder bed selective laser melting 3D printing process is adopted with a laser scanning speed of 900 mm / s, a laser power of 360 W, and a laser line energy input of 0.40 J / mm to prepare a FeMnSi alloy block with a size of 100 mm×10 mm×10 mm.

[0027] A metal wire with a diameter of 1 mm was cut from the bulk FeMnSi alloy prepared in this embodiment for shape memory effect test. The test method refers to "YS / T 1307.2-2019 Test Method for Memory Performance of Nickel-Titanium Shape Memory Alloy Part 2: Bending Test Method". The test temperature is 77K (the metal wire is bent by immersing it in liquid nitrogen to ensure the temperature). The shape memory effect data are shown in Table 2

[0028] Table 2

[0029] Pre-strain (%) Recoverable strain (%) Shape recovery rate (%) 3.51 3.12 89 4.10 3.67 90 5.30 4.56 91 7.90 5.30 67 8.40 5.60 67 9.43 5.34 57

[0030] It can be seen from Table 2 that the bulk FeMnSi alloy prepared in this embodiment has a significant low-temperature shape memory effect, indicating that the present invention uses a FeMnSi alloy composition characterized by high Cr content, high Ni content, and medium Si content for metal powder bed selective laser melting 3D printing, which has good adaptability to 3D printing processes and has significant shape memory effect and tensile strength at low temperatures.

[0031] Example 3

[0032] This embodiment includes the following steps:

[0033] Step 1, rotating and mixing the powder containing the FeMnCrNiSi elemental component at room temperature to obtain a mixed powder; in the powder containing the FeMnCrNiSi elemental component, the mass percentage of Mn is 16%, the mass percentage of Cr is 11%, the mass percentage of Ni is 6%, the mass percentage of Si is 5%, and the balance is Fe;

[0034] Step 2: Using the mixed powder obtained in step 1 as raw material, a metal powder bed selective laser melting 3D printing process is adopted with a laser scanning speed of 900 mm / s, a laser power of 380 W, and a laser line energy input of 0.42 J / mm to prepare a FeMnSi alloy block with a size of 100 mm×10 mm×10 mm.

[0035] A metal wire with a diameter of 1 mm was cut from the FeMnSi alloy block prepared in this embodiment for shape memory effect test. The test method was based on "YS / T 1307.2-2019 Test Method for Memory Performance of Nickel-Titanium Shape Memory Alloy Part 2: Bending Test Method". The test temperature was 77K (the metal wire was bent by immersing it in liquid nitrogen to ensure the temperature). The shape memory effect data are shown in Table 3.

[0036] Table 3

[0037] Pre-strain (%) Recoverable strain (%) Shape recovery rate (%) 3.78 3.43 91 4.11 3.75 91 5.42 4.21 88 7.80 5.70 78 8.12 5.72 70 9.32 5.15 55

[0038] It can be seen from Table 3 that the bulk FeMnSi alloy prepared in this embodiment has a significant low-temperature shape memory effect, indicating that the present invention uses a FeMnSi alloy composition characterized by high Cr content, high Ni content, and medium Si content for metal powder bed selective laser melting 3D printing, which has good adaptability to 3D printing processes and has significant shape memory effect and tensile strength at low temperatures.

[0039] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing FeMnSi alloys with significant low-temperature shape memory effect by 3D printing, characterized in that: The method comprises the following steps: Step 1, rotating and mixing powder containing FeMnCrNiSi elemental components at room temperature to obtain mixed powder; Step 2: Using the mixed powder obtained in step 1 as raw material, a bulk FeMnSi alloy is prepared by a metal powder bed selective laser melting 3D printing process.

2. The method for preparing a FeMnSi alloy having a significant low-temperature shape memory effect by 3D printing according to claim 1, characterized in that: In the powder containing the elemental components of FeMnCrNiSi described in step 1, the mass percentage of Mn is 16%, the mass percentage of Cr is 8% to 11%, the mass percentage of Ni is 6%, the mass percentage of Si is 5% to 5.5%, and the balance is Fe.

3. The method for preparing a FeMnSi alloy having a significant low-temperature shape memory effect by 3D printing according to claim 1, characterized in that: The laser line energy input of the metal powder bed selective laser melting 3D printing process described in step 2 is above 0.35 J / mm.

4. The method for preparing a FeMnSi alloy having a significant low-temperature shape memory effect by 3D printing according to claim 1, characterized in that: A metal wire with a diameter of 1 mm was cut from the bulk FeMnSi alloy obtained in step 2 to perform a shape memory effect test.