Novel invar alloy material with low thermal expansion coefficient and preparation method thereof

Abstract

The invention discloses a novel invar alloy material with a low thermal expansion coefficient and a preparation method thereof. The novel invar alloy material with the low thermal expansion coefficient comprises the following chemical components in percentage by weight: 32.5%-34.5% of Ni, 3%-6% of Co, less than or equal to 0.15% of Si, 0.25%-0.35% of Cu, less than or equal to 0.25% of Mn, 0.15%-0.35% of Nb, less than or equal to 0.05% of C and the balance of Fe and inevitable impurities. The prepared novel invar alloy material with the low thermal expansion coefficient can have the low thermal expansion coefficient and the good tensile strength and ductility at the same time, the average thermal expansion coefficient within the range of 25-150 DEG C is (0.64-0.79) * 10 <-6 > K <-1 >, the density is about 8.0 g / cm < 3 >, the optimal tensile strength is 515 MPa, and the ductility is about 20%.

Description

Technical Field

[0001] The invention relates to a novel Invar alloy material with a low thermal expansion coefficient and a preparation method thereof, belonging to the technical field of Invar alloy material preparation. Background Art

[0002] The most notable feature of Invar alloy is its low thermal expansion, which means it has a small dimensional change under different temperature conditions. This property makes Invar alloy perform well in applications that require precise control of size and shape. In the temperature range of 20℃ to 100℃, the thermal expansion coefficient of classic 4J36 Invar alloy is about 1.1×10 -6 / ℃, the thermal expansion coefficient of 4J40 Invar alloy is 1.3×10 -6 / °C (YB_T 52412014). This property makes Invar alloys 4J36 and 4J40 the materials of choice for manufacturing high-precision equipment and components. For example, in the aerospace field, Invar alloys are used to manufacture precision instruments and thermal protection systems, ensuring dimensional stability under extreme temperatures. In the manufacture of precision measuring equipment and scientific instruments, the use of Invar alloys can effectively avoid measurement errors caused by temperature fluctuations. Components such as microscopes, astronomical telescopes, and measuring instruments have extremely high requirements for dimensional stability. Even slight dimensional changes can significantly affect measurement results. Therefore, the thermal expansion coefficient of Invar alloy is crucial to the measurement results of high-precision equipment and components.

[0003] The alloy's low thermal expansion properties stem from the interaction between iron and nickel atoms within a specific temperature range. The addition of nickel not only imparts a unique crystal structure (primarily face-centered cubic) to the material but also enables adaptive compensation of microscopic stresses by regulating magnetic phase transitions, effectively suppressing thermal expansion. The addition of trace elements such as cobalt (Co) and aluminum (Al) improves the alloy's thermal stability and oxidation resistance, thereby enhancing its mechanical properties at high temperatures. The addition of elements such as Cu and Co can raise the Curie point of Invar alloy. The addition of manganese helps increase the hardness of Invar alloy, especially at low temperatures. Manganese also acts as a deoxidizer, helping to reduce the oxygen content in the alloy and thus improving corrosion resistance. Niobium is a strong carbide former, forming stable NbC carbides in Invar alloy. These carbides are finely dispersed in the matrix, acting as precipitation strengthening, contributing to the alloy's strength and hardness.

[0004] Patent CN114226662B discloses a method for preparing low expansion Invar alloy by annealing, wherein the average thermal expansion coefficient of the alloy at 20℃-100℃ is greater than 1.1×10 -6 / ℃, the thermal expansion coefficient is relatively high. Chinese patent CN116043127A discloses an Invar alloy material with a low thermal expansion coefficient, whose average thermal expansion coefficient at 20℃-160℃ is about 1.30~1.45×10 -6 / ℃, the thermal expansion coefficient is relatively high. Chinese patent CN116555675A discloses a low thermal expansion and high magnetic property Invar alloy and its preparation method. The average linear expansion coefficient at 20-100℃ is about 1.2~1.49×10 -6 / ℃, the high thermal expansion coefficient limits the application of this alloy. Summary of the Invention

[0005] The present invention aims to provide a novel low thermal expansion coefficient Invar alloy material and a preparation method thereof, which can simultaneously have a low thermal expansion coefficient, good tensile strength and elongation.

[0006] In order to achieve the above technical objectives, the present invention will adopt the following technical solutions:

[0007] A new type of Invar alloy material with a low thermal expansion coefficient comprises the following chemical components by weight: Ni: 32.5% to 34.5%, Co: 3% to 6%, Si: ≤0.15%, Cu: 0.25% to 0.35%, Mn: ≤0.25%, Nb: 0.15% to 0.35%, C: ≤0.05%, and the balance being Fe and unavoidable impurities.

[0008] Preferably, the unavoidable impurities include, by weight percentage: S: ≤ 0.02%, P: ≤ 0.02%.

[0009] Another technical object of the present invention is to provide a method for preparing a novel Invar alloy material with a low thermal expansion coefficient, comprising the following steps:

[0010] Step 1: Place the raw materials into a vacuum induction furnace melting device to form a new low expansion coefficient Invar alloy casting; the raw materials contain the following chemical composition by weight percentage: Ni: 32.5% to 34.5%, Co: 3% to 6%, Si: ≤0.15%, Cu: 0.25% to 0.35%, Mn: ≤0.25%, Nb: 0.15% to 0.35%, C: ≤0.05%, and the balance is Fe and unavoidable impurities;

[0011] Step 2: atomizing the new Invar alloy casting through an atomization device to obtain a new Invar alloy powder;

[0012] Step 3: preparing a molten new Invar alloy powder by a laser selective melting process to produce a new Invar alloy with a low thermal expansion coefficient;

[0013] Step 4: heat-treating the produced new low expansion coefficient Invar alloy.

[0014] Preferably, the parameters of the laser selective melting process in step 3 are: laser power: 180 W, scanning speed: 500-700 mm / s, scanning spacing: 0.007 mm, and layer height: 0.03 mm.

[0015] Preferably, the heat treatment process described in step 4 is: solution temperature 840°C±10°C, solution time 1h, quenching treatment, aging temperature 315°C±10°C, aging temperature 1h, and air cooling treatment.

[0016] Preferably, in step 1, the absolute pressure of the vacuum degree should not be higher than 2×10 -3 Pa; a low-pressure inert gas protective atmosphere is provided throughout the smelting process, with a pressure range of 4×10 2 Pa~6×10 2 Pa.

[0017] Preferably, the inert gas is high-purity argon.

[0018] Based on the above technical objectives, the present invention has the following advantages over the prior art:

[0019] The novel low expansion coefficient Invar alloy material of the present invention comprises components comprising an increased content of the element Co and the addition of trace amounts of Cu and Nb, thereby adjusting the magnetic susceptibility of the Invar alloy and increasing the Curie point of the Invar alloy, thereby reducing the thermal expansion coefficient of the Invar alloy material (the average thermal expansion coefficient in the range of 25°C to 150°C is (0.64 to 0.79)).

[0020] ×10 -6 / ℃), and the thermal expansion coefficient of the material within the temperature range of 25-150℃ is α≤0.81×10 -6 / ℃ technical requirements.

[0021] The new low-expansion-coefficient Invar alloy described in this invention is melt-formed using a selective laser melting process. This process promotes the formation of fine carbides, while the addition of Cu promotes solid solution strengthening, significantly increasing the yield strength and tensile strength of the new Invar alloy.

[0022] The new low thermal expansion coefficient Invar alloy material prepared by the present invention has relevant indicators that meet the requirements of YB / T5241-2014 and ASTMF1684-06 standards, and the average thermal expansion coefficient within the range of 25℃ to 150℃ is ≤0.81×10 -6 K -1 , density is about 8.0g / cm 3, which are lower than the typical 4J36 and 4J40 Invar alloy materials, and have significant economic benefits and strategic significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Graphs showing thermal expansion coefficients of the low expansion coefficient novel Invar alloy casting of Example 1 and 4J40 Invar alloy forgings.

[0024] Figure 2 Thermal expansion coefficient curves of the additively manufactured low expansion coefficient new Invar alloy and 4J40 Invar alloy forgings of Examples 2-4.

[0025] Figure 3 These are mechanical property curves of the low expansion coefficient novel Invar alloy castings of Examples 1-4, the additively manufactured low expansion coefficient novel Invar alloy, and the 4J40 Invar alloy forgings. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way serves as any limitation on the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention. Unless otherwise specified, the relative arrangement of components and steps, expressions and numerical values described in these embodiments do not limit the scope of the present invention. Technologies, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods and equipment should be considered part of the specification. In all examples shown and discussed here, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values.

[0027] Example 1

[0028] This embodiment provides a method for preparing a novel low expansion coefficient Invar alloy, which specifically includes the following steps:

[0029] (1) Two different raw materials are heated and melted in a vacuum induction furnace to form a melt. The absolute pressure of the vacuum should not be higher than 2×10 -3 Pa, the smelting process is provided with a low-pressure inert gas protective atmosphere throughout the process. The inert gas is high-purity argon with a pressure range of 4×10 2 Pa~6×10 2Pa. The specific process parameters and steps can be reasonably selected according to the actual situation and will not be described in detail here. The two different raw materials are denoted as DN1 and DN2; the composition of DN1 is: Co: 4.96%, Si: 0.035%, Cu: 0.32%, Mn: 0.103%, Ni: 32.98%, Nb: 0.34%, C: 0.0054%, and the balance is iron and unavoidable impurities; the composition of DN2 is: Co: 5.50%, Si: 0.056%, Cu: 0.32%, Mn: 0.097%, Ni: 32.95%, Nb: 0.18%, C: 0.0073%, and the balance is iron and unavoidable impurities.

[0030] (2) The DN1 and DN2 new low expansion coefficient Invar alloy samples prepared by vacuum melting were heat treated. The heat treatment process was as follows: solution temperature 840℃±10℃, solution time 1h, quenching treatment, aging temperature 315℃±10℃, aging temperature 1h, and air cooling treatment.

[0031] (3) DN1 and DN2 low expansion coefficient new Invar alloy castings and 4J40 forgings were cut into φ6×25 cylinders by wire cutting process. The thermal expansion coefficient of the new low expansion coefficient Invar alloy was measured in the temperature range of 25-150℃ using DIL402SE thermal expansion instrument. The thermal expansion coefficient of the new low expansion coefficient Invar alloy in the temperature range of 25℃~150℃ was ≤0.81×10 -6 K -1 , the relevant thermal expansion coefficient is as follows Figure 1 shown.

[0032] Example 2

[0033] A method for preparing a novel low-expansion-coefficient Invar alloy comprises the following steps: a casting DN2 (material composition: Co: 5.50%, Si: 0.056%, Cu: 0.32%, Mn: 0.097%, Ni: 32.95%, Nb: 0.18%, C: 0.0073%, the remainder being iron and unavoidable impurities) is subjected to aerosolization and powdering through an aerosolization device. The obtained DN2 novel low-expansion-coefficient Invar alloy powder has a particle size of 53 to 150 μm.

[0034] The laser selective melting process is used to prepare and process the DN2 low expansion coefficient new Invar alloy, which specifically includes the following steps:

[0035] Step 1: Customized programming and simulated manufacturing of the DN2 low expansion coefficient new Invar alloy are performed using the additive manufacturing system programming module. Laser additive manufacturing is performed using a cross-scanning process. The laser processing technology is as follows: laser power: 180W, scanning speed: 500mm / s, scanning pitch: 0.007mm, and layer height: 0.03mm.

[0036] Step 2: The DN2 low expansion coefficient new Invar alloy sample obtained in step 1 is heat treated. The heat treatment process is: solution temperature 840℃±10℃, solution time 1h, quenching treatment, aging temperature 315℃±10℃, aging temperature 1h, and air cooling treatment.

[0037] Step 3: Use wire cutting equipment to carry out wire cutting of tensile specimens and thermal expansion specimens of forged 4J40 Invar alloy and three groups of DN2 new low expansion coefficient Invar alloy after heat treatment. The thermal expansion coefficient, mechanical property and density measurements are carried out on the cut specimens respectively.

[0038] The thermal expansion coefficient of the new DN2 low expansion coefficient Invar alloy prepared according to the above process is ≤0.79×10 -6 K -1 , the relevant thermal expansion coefficient curve is as follows Figure 2 As shown in the figure, the tensile strength of the new low expansion coefficient Invar alloy DN2 is 506MPa, the elongation is 18%, and the stress-strain curves of the new low expansion coefficient Invar alloy DN2 and 4J40 forgings are shown in the figure. Figure 3 As shown; the density of the new DN2 low expansion coefficient Invar alloy is 8.02g / cm 3 .

[0039] Example 3

[0040] A method for preparing a new low-expansion coefficient Invar alloy is disclosed. The composition of the casting DN2 is as follows: Co: 5.50%, Si: 0.056%, Cu: 0.32%, Mn: 0.097%, Ni: 32.95%, Nb: 0.18%, C: 0.0073%, with the balance being iron and unavoidable impurities. The DN2 new low-expansion coefficient Invar alloy powder is atomized and pulverized using an atomization device. The resulting powder has a particle size of 53 to 150 μm.

[0041] The laser selective melting process is used to prepare and process the DN2 low expansion coefficient new Invar alloy, which specifically includes the following steps:

[0042] Step 1: Customized programming and simulated manufacturing of the DN2 low expansion coefficient new Invar alloy are performed using the additive manufacturing system programming module. Laser additive manufacturing is performed using a cross-scanning process. The laser processing technology is as follows: laser power: 180W, scanning speed: 600mm / s, scanning pitch: 0.007mm, and layer height: 0.03mm.

[0043] Step 2: The DN2 low expansion coefficient new Invar alloy sample obtained in step 1 is heat treated. The heat treatment process is: solution temperature 840℃±10℃, solution time 1h, quenching treatment, aging temperature 315℃±10℃, aging temperature 1h, and air cooling treatment.

[0044] Step 3: Use wire cutting equipment to carry out wire cutting of tensile specimens and thermal expansion specimens of forged 4J40 Invar alloy and heat-treated DN2 new low expansion coefficient Invar alloy, and perform thermal expansion coefficient measurement, mechanical property measurement and density measurement on the cut specimens respectively.

[0045] The thermal expansion coefficient of the new DN2 low expansion coefficient Invar alloy prepared according to the above process is ≤0.64×10 -6 K -1 , the relevant thermal expansion coefficient curve is as follows Figure 2 As shown in the figure, the tensile strength of the new DN2 low expansion coefficient Invar alloy is 515 MPa, and the elongation is about 20%. The stress-strain curves of the new DN2 low expansion coefficient Invar alloy and 4J40 forging are shown in the figure. Figure 3 As shown; the density of the new DN2 low expansion coefficient Invar alloy is 7.98g / cm 3 .

[0046] Example 4

[0047] A method for preparing a new low-expansion coefficient Invar alloy is disclosed. The composition of the casting DN2 is as follows: Co: 5.50%, Si: 0.056%, Cu: 0.32%, Mn: 0.097%, Ni: 32.95%, Nb: 0.18%, C: 0.0073%, with the balance being iron and unavoidable impurities. The DN2 new low-expansion coefficient Invar alloy powder is atomized and pulverized using an atomization device. The resulting powder has a particle size of 53 to 150 μm.

[0048] The laser selective melting process is used to prepare and process the DN2 low expansion coefficient new Invar alloy, which specifically includes the following steps:

[0049] Step 1: Customized programming and simulated manufacturing of the DN2 low expansion coefficient new Invar alloy are performed using the additive manufacturing system programming module. Laser additive manufacturing is performed using a cross-scanning process. The laser processing technology is as follows: laser power: 180W, scanning speed: 700mm / s, scanning pitch: 0.007mm, and layer height: 0.03mm.

[0050] Step 2: The DN2 low expansion coefficient new Invar alloy sample obtained in step 1 is heat treated. The heat treatment process is: solution temperature 840℃±10℃, solution time 1h, quenching treatment, aging temperature 315℃±10℃, aging temperature 1h, and air cooling treatment.

[0051] Step 3: Use wire cutting equipment to carry out wire cutting of tensile specimens and thermal expansion specimens of forged 4J40 Invar alloy and heat-treated DN2 new low expansion coefficient Invar alloy, and perform thermal expansion coefficient measurement, mechanical property measurement and density measurement on the cut specimens respectively.

[0052] The thermal expansion coefficient of the new DN2 low expansion coefficient Invar alloy prepared according to the above process is ≤0.69×10 -6 K -1 , the relevant thermal expansion coefficient curve is as follows Figure 2 As shown in Figure 2, the tensile strength of the DN2 low expansion coefficient new Invar alloy is 495 MPa and the elongation is 19%. The stress-strain curves of the cast DN1 and DN2 low expansion coefficient new Invar alloys, the additively manufactured DN2 low expansion coefficient new Invar alloy and the 4J40 forging are shown in Figure 2. Figure 3 As shown in the figure, it can be seen that the additively manufactured DN2 low expansion coefficient new Invar alloy has higher tensile strength and yield strength than the cast DN2; at the same time, compared with the mechanical properties of the 4J40 forging, the additively manufactured DN2 low expansion coefficient new Invar alloy has higher yield strength and exhibits better mechanical properties. In addition, the density of the low expansion coefficient new Invar alloy is 8.01g / cm 3 .

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A new type of Invar alloy material with low thermal expansion coefficient, characterized in that: The steel comprises the following chemical compositions by weight: Ni: 32.5% to 34.5%, Co: 3% to 6%, Si: ≤0.15%, Cu: 0.25% to 0.35%, Mn: ≤0.25%, Nb: 0.15% to 0.35%, C: ≤0.05%, and the remainder is Fe and unavoidable impurities.

2. The novel low thermal expansion coefficient Invar alloy material according to claim 1, characterized in that: The inevitable impurities include by weight percentage: S: ≤ 0.02%, P: ≤ 0.02%.

3. A method for preparing a new type of Invar alloy material with low thermal expansion coefficient, characterized in that: The steps include: Step 1: Place the raw materials into a vacuum induction furnace melting device to form a new low expansion coefficient Invar alloy casting; the raw materials contain the following chemical composition by weight percentage: Ni: 32.5% to 34.5%, Co: 3% to 6%, Si: ≤0.15%, Cu: 0.25% to 0.35%, Mn: ≤0.25%, Nb: 0.15% to 0.35%, C: ≤0.05%, and the balance is Fe and unavoidable impurities; Step 2: atomizing the new Invar alloy casting through an atomization device to obtain a new Invar alloy powder; Step 3: preparing a molten new Invar alloy powder by a laser selective melting process to produce a new Invar alloy with a low thermal expansion coefficient; Step 4: heat-treating the produced new low expansion coefficient Invar alloy.

4. The method for preparing the novel low thermal expansion coefficient Invar alloy material according to claim 3, characterized in that: The parameters of the laser selective melting process described in step 3 are: laser power: 180W, scanning speed: 500-700mm / s, scanning spacing: 0.007mm, and layer height: 0.03mm.

5. The method for preparing the novel low thermal expansion coefficient Invar alloy material according to claim 3, characterized in that: The heat treatment process described in step 4 is: solution temperature 840℃±10℃, solution time 1h, quenching treatment, aging temperature 315℃±10℃, aging temperature 1h, and air cooling treatment.

6. The method for preparing the novel low thermal expansion coefficient Invar alloy material according to claim 3, characterized in that: In step 1, the absolute pressure of vacuum should not be higher than 2×10 -3 Pa; a low-pressure inert gas protective atmosphere is provided throughout the smelting process, with a pressure range of 4×10 2 Pa~6×10 2 Pa.

7. The method for preparing the novel low thermal expansion coefficient Invar alloy material according to claim 6, characterized in that: The inert gas is high-purity argon.

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