Iron-nickel-based medium-temperature electrothermal alloy and preparation method thereof

Abstract

The invention relates to an iron-nickel-based medium-temperature electrothermal alloy and a preparation method thereof, and belongs to the technical field of alloy preparation. The electrothermal alloy comprises the following chemical components in percentage by mass: 0.01%-0.03% of C, 0.70%-1.50% of Al, less than or equal to 0.80% of Cr, less than or equal to 0.003% of S, less than or equal to 0.020% of P, 51%-53% of Ni, 0.04%-0.20% of rare earth, 0.80%-1.50% of Ti and a matrix element Fe, wherein the rare earth comprises at least one of Y, La and Ce. Alloy elements such as Al, rare earth and Ti are introduced, so that the oxidation resistance of the alloy is improved, and the service life of the alloy in a medium-temperature environment is greatly prolonged. And meanwhile, on the basis of ensuring excellent mechanical properties, the resistivity of the alloy material is effectively improved, and the resistance temperature coefficient of the alloy material is optimized, so that the alloy material can better meet the performance requirement of the positive temperature coefficient effect, and finally, the applicability, design flexibility and integration degree of the electrothermal alloy in a limited design space are enhanced.

Description

Technical Field

[0001] This application relates to the field of alloy preparation technology, and in particular to an iron-nickel based medium-temperature electrothermal alloy and its preparation method. Background Technology

[0002] Iron-nickel thermistor alloys are widely used in various fields due to their moderate resistivity, large positive temperature coefficient of resistance, good linear relationship between resistance and temperature, and high resistance stability. Iron-nickel thermistor alloys offer advantages such as rapid and reliable heating, automatic temperature control, long service life, noiseless heating, and low power attenuation. Furthermore, their excellent mechanical strength, tensile properties, and toughness make them suitable for overheat protection in continuously operating electrical equipment such as elevators, water pumps, and ovens, as well as in household appliances like electric blankets, irons, and rice cookers. However, the operating temperature range of commonly available iron-nickel thermistor alloy wires is relatively limited, typically operating stably only within the range of 0℃ to 150℃, making it difficult to meet the requirements for long-term stable operation in higher temperature environments. In addition, with the continuous miniaturization and integration of electronic devices, the relatively low resistivity of existing iron-nickel alloy wires makes it difficult to achieve efficient heat output within limited design space, thus restricting their application potential in next-generation compact thermal management scenarios.

[0003] Therefore, there is an urgent need for a high-performance iron-nickel-based alloy that can improve the resistivity of the alloy, enhance its oxidation resistance, and effectively extend its service life under medium-temperature conditions. Summary of the Invention

[0004] This application provides a nickel-based medium-temperature electric heating alloy and its preparation method to solve the following technical problem: how to improve the resistivity of the nickel-based medium-temperature electric heating alloy. In a first aspect, embodiments of this application provide an iron-nickel-based medium-temperature electric heating alloy, wherein the chemical composition of the electric heating alloy, by mass fraction, includes: C: 0.01%~0.03%, Al: 0.70%~1.50%, Cr≤0.80%, S≤0.003%, P≤0.020%, Ni: 51%~53%, rare earth: 0.04%~0.20%, Ti: 0.80%~1.50%, and the base element Fe; The rare earth element includes at least one of Y, La and Ce, and the microstructure of the iron-nickel based medium-temperature electric heating alloy contains Ni3(Al,Ti) γ′ ordered phase, oxide / carbonitride nanoparticles, grains refined by at least one of rare earth elements Y, La and Ce, and Ni-Fe solid solution lattice distortion.

[0005] Optionally, the resistivity of the electrothermal alloy is 0.54 Ω·mm. -2 m -1~0.70Ω.mm -2 m -1 The resistivity is obtained by the combined effect of the grain boundary increase generated by the Ni3(Al,Ti) γ′ ordered phase, the oxide / carbonitride nanoparticles, and at least one of the rare earth elements Y, La and Ce refining the grains of the iron-nickel-based medium-temperature electric heating alloy, as well as the electron scattering effect generated by the Ni-Fe solid solution lattice distortion.

[0006] Optionally, the rapid life value of the heating alloy at 900℃ is ≥150h. The rapid life value is obtained by the synergistic effect of at least one of the rare earth elements Y, La and Ce on the grain boundaries of the iron-nickel-based medium-temperature heating alloy and the pinning effect of the ordered Ni3(Al,Ti) γ′ on the grain boundaries of the iron-nickel-based medium-temperature heating alloy.

[0007] Secondly, embodiments of this application provide a method for preparing the electrothermal alloy described in the first aspect, the method comprising: Through refining and casting, an alloy ingot having the chemical composition described in any one of claims 1 to 3 is obtained; The alloy ingot is heated and rolled sequentially to obtain wire rod; The wire rod is subjected to heat treatment, descaling, drawing and annealing in sequence to obtain an electrothermal alloy.

[0008] Optionally, the refining temperature is 1500℃~1650℃, and the casting temperature is 1500℃~1550℃.

[0009] Optionally, the heating temperature is 1120℃~1180℃, and the heating time is 90min~400min.

[0010] Optionally, the initial rolling temperature is 1120℃~1180℃.

[0011] Optionally, the heat treatment temperature is 950℃~1050℃, and the heat treatment holding time is 2.0h~4.0h.

[0012] Optionally, the descaling includes at least one of laser cleaning, mechanical polishing, plasma cleaning, wire strip peeling, acid washing, and alkaline washing.

[0013] Optionally, the descaling includes acid washing and alkaline washing, wherein the temperature of the alkaline washing is 600℃~800℃ and the time of the alkaline washing is 3min~5min.

[0014] Optionally, the concentration of the pickling acid solution is ≥180g / L, and the pickling time is 30min~40min.

[0015] Optionally, the annealing temperature is 1000℃~1150℃.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a nickel-based medium-temperature heating alloy. The chemical composition of the heating alloy, by mass fraction, includes: C: 0.01%~0.03%, Al: 0.70%~1.50%, Cr≤0.80%, S≤0.003%, P≤0.020%, Ni: 51%~53%, rare earth elements: 0.04%~0.20%, Ti: 0.80%~1.50%, and the matrix element Fe; wherein the rare earth elements include at least one of Y, La, and Ce. Through a multi-element synergistic strategy of "solid solution strengthening," "second phase precipitation," and "grain boundary engineering," the key technical problem of insufficient resistivity in nickel-based heating alloys is addressed. The physical essence of increasing resistivity is to increase the resistance to the movement of free electrons in the alloy. This scheme achieves this goal through the following mechanism: First, by strictly controlling the mass fractions of Al (0.70%~1.50%) and Ti (0.80%~1.50%), a large number of dispersed Ni3(Al, Ti) and other γ′ ordered phases, as well as stable oxide and carbonitride particles, are formed in the alloy. These nanoscale second-phase particles act as scattering centers, increasing electron scattering and thus directly improving resistivity. Second, by adding rare earth elements such as Y, La, and Ce (0.04%~0.20%), their strong deoxidation and desulfurization capabilities are utilized to preferentially form high-melting-point compounds with impurities such as oxygen and sulfur, purifying the grain boundaries. Pure grain boundaries reduce impurity scattering, but more importantly, the addition of rare earth elements refines the grains and increases the total grain boundary area. Grain boundaries themselves are effective sources of electron scattering, thus indirectly contributing to the increase in resistivity. Furthermore, precisely controlling the mass fraction of Ni to 51%~53% and forming a solid solution with the Fe matrix in a specific ratio induces lattice distortion and generates a lattice stress field, which also enhances the electron scattering effect.

[0017] In summary, this composition design does not rely on a single element, but rather achieves a significant increase in the resistivity of the alloy through the combined effects of multiple mechanisms, such as Al and Ti forming scattering particles, rare earth purification and increasing grain boundaries, and Ni and Fe matrix solid solution distortion. This ultimately overcomes the technical bottleneck of low resistivity in traditional iron-nickel alloys. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart illustrating an iron-nickel-based medium-temperature electrothermal alloy and its preparation method is provided for embodiments of this application. Figure 2 The oxidation weight gain rate at 600°C is provided for Example 1 and Comparative Examples 1-2 of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0022] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges between 1 and 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "contains" used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship. "And / or" indicates that multiple situations can exist individually or simultaneously. Expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0023] In a first aspect, embodiments of this application provide an iron-nickel-based medium-temperature electric heating alloy, wherein the chemical composition of the electric heating alloy, by mass fraction, includes: C: 0.01%~0.03%, Al: 0.70%~1.50%, Cr≤0.80%, S≤0.003%, P≤0.020%, Ni: 51%~53%, rare earth: 0.04%~0.20%, Ti: 0.80%~1.50%, and the base element Fe; The rare earth element includes at least one of Y, La and Ce, and the microstructure of the iron-nickel based medium-temperature electric heating alloy contains Ni3(Al,Ti) γ′ ordered phase, oxide / carbonitride nanoparticles, grains refined by at least one of rare earth elements Y, La and Ce, and Ni-Fe solid solution lattice distortion.

[0024] The positive effects of limiting the C mass fraction to 0.01%~0.03% are: it can fully utilize the solid solution strengthening effect of C to improve the alloy strength, and it can also reduce the precipitation of harmful carbides at grain boundaries, thereby effectively improving the alloy's ductility, toughness, processing performance, and long-term high-temperature microstructure stability. For example, the C mass fraction can be 0.01%, 0.02%, 0.03%, etc.

[0025] The positive effects of limiting the Al mass fraction to 0.70%~1.50% include: Al effectively isolates oxygen by forming a dense Al2O3 oxide film, inhibiting the oxidation process and thus extending the alloy's service life; simultaneously, it can improve and stabilize the alloy's resistivity. However, excessively high Al mass fractions can lead to a decrease in the temperature coefficient of resistance and increase processing difficulty. For example, the Al mass fraction can be 0.70%, 0.80%, 0.90%, 1.00%, 1.10%, 1.20%, 1.30%, 1.40%, 1.50%, etc.

[0026] The positive effects of limiting the Cr mass fraction to ≤0.80% include: Cr can prevent the formation of excessive brittle phases, ensuring that the alloy has good hot working plasticity and cold deformation ability, while maintaining high resistivity and stable high-temperature performance. For example, the Cr mass fraction can be 0.10%, 0.20%, 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, etc.

[0027] The positive effects of limiting the mass fraction of sulfur (S) to ≤0.003% include: S can reduce the formation of low-melting-point sulfides at grain boundaries, thereby effectively improving the hot workability, high-temperature ductility, and microstructural stability of the alloy under long-term use. For example, the mass fraction of S can be 0.001%, 0.002%, 0.003%, etc.

[0028] The positive effects of limiting the mass fraction of phosphorus (P) to ≤0.020% include: P can effectively inhibit grain boundary embrittlement and improve the hot working properties and high-temperature mechanical properties of the alloy. For example, the mass fraction of P can be 0.010%, 0.015%, 0.020%, etc.

[0029] The positive effects of limiting the Ni mass fraction to 51%~53% are as follows: Ni expands and stabilizes the austenite phase region, suppressing the martensitic transformation temperature to below room temperature. This ensures the high-temperature strength of the alloy while maintaining the stability of the temperature coefficient of resistance through precise control of the nickel-iron ratio. For example, the Ni mass fraction can be 51%, 52%, 53%, etc.

[0030] The positive effects of limiting the mass fraction of rare earth elements to 0.04%~0.20% include: rare earth elements can form stable rare earth compounds with elements such as N, O, and S in the alloy, effectively reducing the content of inclusions and ensuring that the rare earth compounds are uniformly dispersed in the alloy; simultaneously, rare earth elements can inhibit grain growth, refine the grain structure, and reduce crack formation, thereby improving the strength and plasticity of the alloy at both high and room temperature. Furthermore, rare earth elements can enhance the adhesion and density of the oxide film, thus improving the high-temperature oxidation resistance of the alloy. For example, the mass fraction of rare earth elements can be 0.05%, 0.10%, 0.15%, 0.20%, etc.

[0031] The positive effects of limiting the Ti mass fraction to 0.80%~1.50% include: During smelting, Ti acts as a strong deoxidizer, effectively improving the purity of molten steel. It also combines with C and N to form carbonitrides, which act as heterogeneous nucleation sites, refining the solidification structure. In hot working and subsequent treatments, carbonitrides can pin grain boundaries, thereby improving the mechanical properties of the alloy. Furthermore, Ti promotes the formation of a dense alumina film, enhancing the alloy's oxidation resistance, and its addition has no significant effect on the temperature coefficient of electrical resistance. For example, the mass fraction of Ti can be 0.80%, 0.90%, 1.00%, 1.10%, 1.20%, 1.30%, 1.40%, 1.50%, etc.

[0032] Fe is a matrix element, and the specific content / range of Fe can be obtained through the upper and lower limit formulas of the component, that is: The sum of the percentages of all components in a composition should equal 100%, and the content ranges of several components should meet the following conditions: the upper limit of a certain component + the lower limit of other components ≤ 100; the lower limit of a certain component + the upper limit of other components ≥ 100. Furthermore, the specific content of Fe is made up to 100% by the actual detected values ​​of the other chemical components mentioned above, together with any unlisted active elements and / or impurity elements, and Fe must constitute the absolute proportion as a matrix element.

[0033] In some embodiments, the resistivity of the electrothermal alloy is 0.54 Ω·mm. -2 m -1 ~0.70Ω.mm -2 m -1The resistivity is obtained by the combined effect of the grain boundary increase generated by the Ni3(Al,Ti) γ′ ordered phase, the oxide / carbonitride nanoparticles, and at least one of the rare earth elements Y, La and Ce refining the grains of the iron-nickel-based medium-temperature electric heating alloy, as well as the electron scattering effect generated by the Ni-Fe solid solution lattice distortion.

[0034] The resistivity of the heating alloy is 0.54 Ω·mm. -2 m -1 ~0.70Ω.mm -2 m -1 This allows for increased power density in the alloy, enabling efficient heating within limited design space and meeting the core requirements of self-regulating heating elements for alloy resistivity, thereby enhancing performance. For example, the resistivity of the heating alloy can be 0.54 Ω·mm. -2 m -1 0.56Ω.mm -2 m -1 0.58Ω.mm -2 m -1 0.60Ω.mm -2 m -1 0.62Ω.mm -2 m -1 0.64Ω.mm -2 m -1 0.66Ω.mm -2 m -1 0.68Ω.mm -2 m -1 0.70Ω.mm -2 m -1 wait.

[0035] In some embodiments, the rapid lifetime value of the heating alloy at 900°C is ≥150h. The rapid lifetime value is obtained by the synergistic effect of at least one of the rare earth elements Y, La and Ce on the grain boundaries of the iron-nickel-based medium-temperature heating alloy and the pinning effect of the ordered Ni3(Al,Ti) γ′ on the grain boundaries of the iron-nickel-based medium-temperature heating alloy.

[0036] The rapid life value of the heating alloy at 900℃ is ≥150h, which demonstrates the alloy's excellent oxidation resistance and structural stability at 900℃, extending the service life and reliability of the heating element under high-temperature conditions. For example, the rapid life value of the heating alloy at 900℃ can be 150h, 152h, 154h, 156h, 158h, 160h, etc.

[0037] Figure 1This is a flowchart illustrating an iron-nickel-based medium-temperature electrothermal alloy and its preparation method, provided as an embodiment of this application.

[0038] Please see Figure 1 Secondly, this application provides a method for preparing the electrothermal alloy described in the first aspect, the method comprising: S1. By refining and casting, an alloy ingot having the chemical composition described in any one of claims 1 to 3 is obtained; S2. The alloy ingot is heated and rolled sequentially to obtain wire rod; S3. The wire rod is subjected to heat treatment, descaling, drawing and annealing in sequence to obtain an electrothermal alloy.

[0039] In the above technical solution, firstly, molten steel is prepared according to the chemical composition and smelted in a vacuum induction furnace or a medium-frequency induction furnace. Nickel plates, pure iron, carbon particles, and sponge titanium are placed in a crucible and melted. After melting, the remaining micro-alloying elements are added through a vacuum feeding bin. After refining and temperature adjustment, the alloy is vacuum-cast under electric charge. After casting, the alloy is cooled with the furnace and demolded after void breaking to obtain an alloy ingot. Secondly, the obtained alloy ingot is heated in a heating furnace and rolled to obtain wire rod. Finally, the wire rod is heat-treated, descaled to remove the oxide film on the surface of the wire rod, drawn, and annealed to obtain an electrothermal alloy.

[0040] In some embodiments, the refining temperature is 1500℃~1650℃, and the casting temperature is 1500℃~1550℃.

[0041] The refining temperature is between 1500℃ and 1650℃ to ensure the full dissolution of alloying elements, melt purity, and compositional uniformity. For example, refining temperatures can be 1500℃, 1550℃, 1600℃, 1650℃, etc. The casting temperature is between 1500℃ and 1550℃ to ensure the fluidity of the molten steel while refining the solidification structure, avoiding casting defects, and optimizing overall performance. For example, casting temperatures can be 1500℃, 1510℃, 1520℃, 1530℃, 1540℃, 1550℃, etc.

[0042] In some embodiments, the heating temperature is 1120℃~1180℃, and the heating time is 90min~400min.

[0043] The heating temperature is between 1120℃ and 1180℃ to ensure that the alloy ingot reaches the initial rolling temperature both internally and externally. Excessive heating temperature can easily lead to surface oxidation, grain coarsening, and rolling cracks in the alloy ingot; insufficient heating temperature will deteriorate the thermoplasticity of the alloy ingot, also increasing the risk of cracking. Examples of suitable heating temperatures include 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, and 1180℃. The heating time is between 90min and 400min to ensure uniform heating of the alloy ingot both internally and externally. Excessive heating time can easily lead to grain coarsening and surface oxidation in the alloy ingot; insufficient heating time will prevent the core of the alloy ingot from reaching the set temperature, resulting in internal cracking due to concentrated thermal stress during rolling. Examples of suitable heating times include 100min, 150min, 200min, 250min, 300min, 350min, and 400min.

[0044] In some embodiments, the initial rolling temperature is 1120°C to 1180°C.

[0045] When the initial rolling temperature is between 1120℃ and 1180℃, the alloy exhibits good thermoplasticity, which is beneficial for hot working and forming. Excessively high initial rolling temperatures can easily lead to surface oxidation, grain coarsening, and rolling cracks; conversely, excessively low initial rolling temperatures reduce the alloy's thermoplasticity, making it prone to cracking during deformation. For example, the initial rolling temperature can be 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, or 1180℃.

[0046] In some embodiments, the heat treatment temperature is 950℃~1050℃, and the heat treatment holding time is 2.0h~4.0h.

[0047] The heat treatment temperature is between 950℃ and 1050℃ to ensure sufficient solid solution of alloying elements, homogenization of the microstructure, and elimination of processing stress. Examples of heat treatment temperatures include 950℃, 970℃, 990℃, 1010℃, 1030℃, and 1050℃. The holding time for heat treatment is between 2.0h and 4.0h to ensure sufficient diffusion of elements and prevent abnormal grain growth, thereby optimizing the overall mechanical properties of the alloy. Examples of holding times for heat treatment include 2.0h, 2.5h, 3.0h, 3.5h, and 4.0h.

[0048] In some embodiments, the descaling includes at least one of laser cleaning, mechanical polishing, plasma cleaning, wire strip peeling, acid washing, and alkaline washing.

[0049] Laser cleaning: High-energy pulsed lasers cause surface contaminants (oxide scale) to vibrate, vaporize, or peel off instantaneously. Mechanical grinding: Physical friction using grinding wheels, belts, abrasives, etc., removes the surface layer. Plasma method: Utilizes the high energy of plasma active particles to physically bombard and chemically react with surface contaminants. Wire rod peeling: Using precision turning tools to continuously machine away the surface layer (including oxide scale) of the wire rod. Acid pickling: Utilizes acid to chemically react with the oxide scale, dissolving and peeling it off. Alkali pickling: Utilizes the intense thermal shock and chemical corrosion of high-temperature molten alkali (such as sodium hydroxide) to crack and loosen dense oxide scale, especially effective for removing insoluble silicates, and is often used in conjunction with acid pickling. Descaling is used to thoroughly remove oxide scale and contaminants from the surface of wire rods, providing a clean substrate for subsequent hot working, heat treatment, or drawing processes, thereby ensuring the surface quality and performance consistency of the final product.

[0050] In some embodiments, the descaling includes alkaline washing and acid washing, wherein the alkaline washing temperature is 600℃~800℃ and the alkaline washing time is 3min~5min.

[0051] The alkaline washing temperature is between 600℃ and 800℃, utilizing the high-temperature thermal shock effect of molten alkali to rapidly crack and peel off the oxide scale. The alkaline washing time is between 3 and 5 minutes, ensuring sufficient removal of the oxide scale while avoiding excessive corrosion of the substrate or damage to grain boundaries. For example, the alkaline washing temperature can be 600℃, 650℃, 700℃, 750℃, 800℃, etc.; the alkaline washing time can be 3 minutes, 4 minutes, 5 minutes, etc.

[0052] In some embodiments, the concentration of the pickling acid solution is ≥180g / L, and the pickling time is 30min~40min.

[0053] The acid concentration for pickling is ≥180 g / L to ensure sufficient chemical reaction kinetics and efficient dissolution of residual oxides and sparingly soluble inclusions after alkaline pretreatment. The pickling time is between 30 and 40 minutes to thoroughly remove surface residues while avoiding excessive corrosion of the base metal and the risk of hydrogen embrittlement due to hydrogen permeation. For example, the acid concentration for pickling can be 180 g / L, 182 g / L, 184 g / L, 186 g / L, 188 g / L, 190 g / L, etc.; and the pickling time can be 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, 40 minutes, etc.

[0054] In some embodiments, the annealing temperature is 1000°C to 1150°C.

[0055] Annealing at temperatures between 1000℃ and 1150℃ effectively eliminates processing stress and dislocations, thereby improving the mechanical properties of the finished product. Excessively high annealing temperatures can lead to coarse alloy grains, while excessively low temperatures can result in excessively high alloy strength and deteriorated processing performance. For example, annealing temperatures can be 1000℃, 1050℃, 1100℃, 1150℃, etc.

[0056] The product prepared by the method of preparing the electrothermal alloy is the aforementioned electrothermal alloy. Since the method of preparing the electrothermal alloy adopts some or all of the technical solutions of the electrothermal alloy embodiments, it has at least all the beneficial effects brought about by the technical solutions of the aforementioned embodiments, which will not be elaborated here.

[0057] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0058] The chemical composition (mass percentage / %) of the examples and comparative examples is shown in Table 1.

[0059] Table 1

[0060] Example 1 Through refining and casting, an alloy ingot with the chemical composition described in Example 1 of Table 1 was obtained; wherein the refining temperature was 1600℃ and the casting temperature was 1520℃.

[0061] The alloy ingot is heated to 1150°C for 100 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1130°C to obtain wire rod.

[0062] The wire rod is heat-treated at 1050℃ for 2.5 hours. Then, it is descaled by immersing in molten sodium oxide at 700℃ for 3 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 180 g / L for 30 minutes. The surface residue is rinsed off with water and the rod is then dried. The wire rod is then drawn. Finally, it is annealed at 1050℃ to obtain the electrothermal alloy.

[0063] Example 2 Through refining and casting, an alloy ingot with the chemical composition described in Example 2 of Table 1 was obtained; wherein the refining temperature was 1610°C and the casting temperature was 1530°C.

[0064] The alloy ingot is heated to 1150°C for 120 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1140°C to obtain wire rod.

[0065] The wire rod is heat-treated at 1050℃ for 2 hours. Then, it is descaled by immersing in molten sodium oxide at 680℃ for 4 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 185 g / L for 32 minutes. The surface residue is rinsed off with water and the rod is dried. The wire rod is then drawn. Finally, it is annealed at 1030℃ to obtain the electrothermal alloy.

[0066] Example 3 Through refining and casting, an alloy ingot with the chemical composition described in Example 3 of Table 1 was obtained; wherein the refining temperature was 1600℃ and the casting temperature was 1540℃.

[0067] The alloy ingot is heated to 1150°C for 120 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1150°C to obtain wire rod.

[0068] The wire rod is heat-treated at 1040℃ for 3 hours. Then, it is descaled by immersing in molten sodium oxide at 700℃ for 3 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 180 g / L for 35 minutes. The surface residue is rinsed off with water and the rod is dried. The wire rod is then drawn. Finally, it is annealed at 1050℃ to obtain the electrothermal alloy.

[0069] Example 4 Through refining and casting, an alloy ingot with the chemical composition described in Example 4 of Table 1 was obtained; wherein the refining temperature was 1610°C and the casting temperature was 1510°C.

[0070] The alloy ingot is heated to 1160°C for 100 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1150°C to obtain wire rod.

[0071] The wire rod is heat-treated at 1050℃ for 2.5 hours. Then, it is descaled by immersing in molten sodium oxide at 720℃ for 3 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 186 g / L for 35 minutes. The surface residue is rinsed off with water and the rod is dried. The wire rod is then drawn. Finally, it is annealed at 1080℃ to obtain the electrothermal alloy.

[0072] Example 5 Through refining and casting, an alloy ingot with the chemical composition described in Example 5 of Table 1 was obtained; wherein the refining temperature was 1610°C and the casting temperature was 1550°C.

[0073] The alloy ingot is heated to 1150°C for 150 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1150°C to obtain wire rod.

[0074] The wire rod is heat-treated at 1000℃ for 3.5 hours. Then, it is descaled by immersing in molten sodium oxide at 680℃ for 5 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 184 g / L for 30 minutes. The surface residue is rinsed off with water and the rod is then dried. The wire rod is then drawn. Finally, it is annealed at 1030℃ to obtain the electrothermal alloy.

[0075] Comparative Example 1 The alloy ingot was refined at a temperature of 1600℃, then cast at a temperature of 1550℃, and finally purified using a single-phase electroslag remelting furnace to obtain the alloy ingot with the chemical composition described in Comparative Example 1 in Table 1; wherein Y2O was added to the purified slag. 3， The mass ratio of Y2O3:CaO:CaF2 is 15:5:80, and the amount of refining slag per furnace is 5 kg.

[0076] The alloy ingot is heated to 1150°C for 150 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1150°C to obtain wire rod.

[0077] The wire rod is heat-treated at 1030℃ for 3 hours. Then, it is descaled by immersing in molten sodium oxide at 700℃ for 3 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 182 g / L for 32 minutes. The surface residue is rinsed off with water and the rod is then dried. The wire rod is then drawn. Finally, it is annealed at 1050℃ to obtain the electrothermal alloy.

[0078] Comparative Example 2 Through refining and casting, alloy ingots with the chemical composition described in Comparative Example 2 in Table 1 were obtained; wherein the refining temperature was 1600℃ and the casting temperature was 1530℃.

[0079] The alloy ingot is heated to 1160°C for 120 minutes; then the alloy ingot is rolled at an initial rolling temperature of 1150°C to obtain wire rod.

[0080] The wire rod is heat-treated at 1030℃ for 3 hours. Then, it is descaled by immersing in molten sodium oxide at 700℃ for 3 minutes, rinsing with water, and then immersing in sulfuric acid at a concentration of 182 g / L for 32 minutes. The surface residue is rinsed off with water and the rod is then dried. The wire rod is then drawn. Finally, it is annealed at 1050℃ to obtain the electrothermal alloy.

[0081] The rapid lifetime and resistivity of the examples and comparative examples are shown in Table 2.

[0082] Table 2

[0083] The data tables above provide a clear comparison of the differences between various embodiments and comparative examples. The following conclusions can be drawn: As can be seen from the data in Table 2, the electrothermal alloy provided in this application embodiment has a rapid lifespan of 150h~155h at 900℃ and a resistivity of 0.54Ωmm. -2 m -1 ~0.70Ω.mm -2 m -1 .

[0084] From Examples 1-5 and Comparative Examples 1-2, the rapid lifetime value (≥150h) at 900℃ and the resistivity (≥0.54Ω / mm) at 20℃ in Examples 1-5 were obtained. -2 m -1 Both of these performance characteristics are significantly better than those of Comparative Examples 1 and 2, which fully demonstrates that the embodiments of this application have achieved a synergistic improvement in high resistivity and excellent high-temperature oxidation resistance through component optimization. The technical effect is significant, stable and innovative.

[0085] Appendix Figure 2 Detailed explanation: Figure 2 The oxidation weight gain at 600°C is provided for Examples 1 and Comparative Examples 1-2 of this application. Figure 2 It can be seen that at a temperature of 600°C, the oxidative weight gain rate of Example 1 of this application is lower than that of Comparative Example 1 and Comparative Example 2, indicating that its antioxidant performance is superior.

[0086] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: The present invention provides an iron-nickel-based medium-temperature electric heating alloy. By rationally designing the alloy composition and optimizing the preparation process, the resistivity of the electric heating alloy is improved, making it more suitable for the design requirements of miniaturized, high-power-density electric heating elements. At the same time, the oxidation resistance of the electric heating alloy is effectively enhanced, significantly extending its service life in medium-temperature environments. In addition, the good mechanical and processing properties of the electric heating alloy are maintained, taking into account both the practicality and production feasibility of the product.

[0087] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. An iron-nickel based intermediate temperature electrothermal alloy, characterized in that, The chemical composition of the electrothermal alloy in mass fraction includes: C: 0.01%~0.03%, Al: 0.70%~1.50%, Cr≤0.80%, S≤0.003%, P≤0.020%, Ni: 51%~53%, rare earth: 0.04%~0.20%, Ti: 0.80%~1.50%, and base element Fe; The rare earth includes at least one of Y, La and Ce, the microstructure of the iron-nickel based medium temperature electrothermal alloy contains Ni3(Al, Ti) γ' ordered phase, oxide / carbonitride nanoparticles, grains refined by at least one of Y, La and Ce, and Ni-Fe solid solution lattice distortion.

2. The electrothermal alloy of claim 1, wherein, the electrical resistivity of the electrothermal alloy is 0.54 Ω.mm - 2 m -1 ~0.70 Ω.mm -2 m -1 the electrical resistivity is synergistically produced by the electron scattering effect of the Ni3(Al,Ti) γ' ordered phase, the grain boundary increase effect produced by the oxide / carbonitride nanoparticles, the at least one of the rare earth elements Y, La and Ce refining the grain of the iron-nickel based medium temperature electrothermal alloy, and the Ni-Fe solid solution lattice distortion.

3. The electrothermal alloy of claim 1, wherein, The rapid life value of the electrothermal alloy at 900℃ is ≥150h, which is obtained by the purification effect of the at least one of Y, La and Ce on the grain boundary of the iron-nickel based medium temperature electrothermal alloy, and the pinning effect of the Ni3(Al, Ti) γ' ordered phase on the grain boundary of the iron-nickel based medium temperature electrothermal alloy.

4. A method of producing the electrocaloric alloy according to any one of claims 1 to 3, characterized in that, The method comprises: Through refining and casting, an alloy ingot with the chemical composition of any one of claims 1~3 is obtained; The alloy ingot is sequentially heated and rolled to obtain a wire rod; The wire rod is sequentially heat treated, descaled, drawn and annealed to obtain an electrothermal alloy.

5. The method of claim 4, wherein, The temperature of the refining is 1500℃~1650℃, and the temperature of the casting is 1500℃~1550℃.

6. The method of claim 4, wherein, The temperature of the heating is 1120℃~1180℃, and the time of the heating is 90min~400min.

7. The method of claim 4, wherein, The rolling temperature is 1120℃~1180℃.

8. The method of claim 4, wherein, The temperature of the heat treatment is 950℃~1050℃, and the holding time of the heat treatment is 2.0h~4.0h.

9. The method of claim 4, wherein, The descaling includes at least one of laser cleaning, mechanical polishing, plasma method, wire rod peeling, pickling and alkaline cleaning; and / or, The descaling includes alkaline cleaning and pickling, the temperature of the alkaline cleaning is 600℃~800℃, and the time of the alkaline cleaning is 3min~5min; and / or, The acid concentration of the pickling is ≥180g / L, and the time of the pickling is 30min~40min.

10. The method of claim 4, wherein, The temperature of the annealing is 1000℃~1150℃.

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