High-resistance long-life ferro-nickel electrothermal alloy and preparation method thereof

Abstract

The invention relates to a high-resistance long-life ferro-nickel electrothermal alloy and a preparation method thereof, and belongs to the technical field of alloy preparation. The nickel-iron electrothermal alloy comprises the following chemical components in percentage by mass: 0.01%-0.03% of C, 0.8%-2.0% of Si, less than or equal to 0.8% 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%-0.2% of Y, 0.02%-0.07% of Hf and a matrix element Fe. Elements Si, Y and Hf are added into the iron-nickel alloy, so that the working temperature of the alloy resistance wire is remarkably increased, the resistivity is optimized, the application field of the alloy resistance wire is greatly expanded, and the design flexibility and integration degree of a product are improved.

Description

Technical Field

[0001] The present application relates to the field of alloy preparation, and in particular to a high-resistance and long-life nickel-iron electric heating alloy and a preparation method thereof. Background Art

[0002] Nickel-iron electric heating alloy has medium resistivity, large and positive resistance temperature coefficient, its resistance value is linearly related to temperature, and the resistance stability is good. It has the advantages of fast heating, high safety factor, automatic constant temperature, long heating life, no noise when heating, small power attenuation, high mechanical strength, high material tensile strength, good toughness, etc. It is mainly used in elevators, water pumps, continuously running electrical equipment, ovens, etc. to prevent overheating and over-temperature. Some are used in household appliances such as electric blankets, electric irons, and rice cookers. The working temperature range of the common nickel-iron electric heating alloy wires on the market is limited, and it can usually only work stably within the range of 0-150℃. This limits their application possibilities in higher temperature environments, especially in situations where long-term stable work is required, and traditional nickel-iron alloy resistance wires cannot meet the needs. In addition, with the trend of electronic equipment towards miniaturization and integration, higher requirements are also put forward for the space occupation of resistance wires. However, the existing nickel-iron electric heating alloy resistance wires are difficult to achieve efficient heat generation under limited design space due to their lower resistivity than traditional electric heating alloys. Summary of the invention

[0003] The present application provides a high-resistance and long-life nickel-iron electric heating alloy and a preparation method thereof to solve the following technical problem: how to simultaneously improve the high-temperature oxidation resistance and resistivity of the nickel-iron electric heating alloy.

[0004] In a first aspect, an embodiment of the present application provides a high-resistance and long-life nickel-iron electrothermal alloy. The chemical composition of the nickel-iron electrothermal alloy, measured by mass fraction, includes: C: 0.01%~0.03%, Si: 0.8%~2.0%, Cr≤0.8%, S≤0.003%, P≤0.020%, Ni: 51%~53%, Y: 0.04%~0.2%, Hf: 0.02%~0.07%, and matrix element Fe.

[0005] Optionally, the resistivity of the nickel-iron electrothermal alloy is 0.50 μΩ.mm -2 m -1 ~0.60μΩ.mm -2 m -1 .

[0006] Optionally, the nickel-iron electrothermal alloy satisfies: in a 900° C. rapid life test, the rapid life value is >250h.

[0007] In a second aspect, an embodiment of the present application provides a method for preparing the high-resistance and long-life nickel-iron electrothermal alloy described in the first aspect, the method comprising:

[0008] Obtaining a nickel-iron electric heating alloy raw material containing the chemical composition;

[0009] Refining and pouring the nickel-iron electric heating alloy raw material in sequence to obtain a nickel-iron alloy steel ingot;

[0010] The nickel-iron alloy steel ingot is sequentially heated and rolled to obtain a nickel-iron alloy wire rod;

[0011] The nickel-iron alloy wire rod is subjected to heat treatment, drawing and annealing treatment in sequence to obtain the nickel-iron electrothermal alloy.

[0012] Optionally, the pouring temperature is 1500°C to 1550°C.

[0013] Optionally, the heating temperature is 1120°C to 1180°C.

[0014] Optionally, the heating time is 90 min to 400 min.

[0015] Optionally, the starting temperature of the rolling is 1120°C to 1180°C.

[0016] Optionally, the temperature of the heat treatment is 950°C to 1050°C, and the insulation time of the heat treatment is 2h to 4h.

[0017] Optionally, the annealing treatment is performed at a temperature of 1000°C to 1150°C.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The embodiment of the present application provides a high-resistance and long-life nickel-iron electric heating alloy, and the chemical composition of the nickel-iron electric heating alloy includes, by mass fraction: C: 0.01% to 0.03%, Si: 0.8% to 2.0%, Cr≤0.8%, S≤0.003%, P≤0.020%, Ni: 51% to 53%, Y: 0.04% to 0.2%, Hf: 0.02% to 0.07%, and matrix element Fe. By adding elements Si, Y and Hf to the iron-nickel alloy, the operating temperature of the alloy resistance wire is significantly increased and the resistivity is optimized, thereby greatly expanding its application field and improving the design flexibility and integration of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic flow chart of a method for preparing a high-resistance and long-life nickel-iron electrothermal alloy provided in an embodiment of the present application;

[0023] Figure 2 This is a graph showing the change in weight gain rate over time of 0.8 mm bright alloy wire provided in an embodiment of the present application in an air environment at 600°C. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0025] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0026] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the weight ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the weight of substance A: the weight of substance B: the weight of substance C = 1:2:3.

[0027] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0028] In a first aspect, an embodiment of the present application provides a high-resistance and long-life nickel-iron electrothermal alloy. The chemical composition of the nickel-iron electrothermal alloy, measured by mass fraction, includes: C: 0.01%~0.03%, Si: 0.8%~2.0%, Cr≤0.8%, S≤0.003%, P≤0.020%, Ni: 51%~53%, Y: 0.04%~0.2%, Hf: 0.02%~0.07%, and matrix element Fe.

[0029] Si will react with air to generate SiO2. SiO2 is between the matrix and the oxide film of the alloy, and can also isolate oxygen. It is an important part of the anti-oxidation mechanism, which can reduce the oxidation rate of the alloy, thereby extending the service life. Si can increase the resistivity, and keeping the mass fraction of Si stable is beneficial to the stability of the alloy resistance. However, if the mass fraction of Si is higher than 2.0%, the resistance temperature correction coefficient will be reduced, affecting the linearity of the material resistance and temperature. Combined with the oxidation resistance, resistivity and high-temperature structural stability, the mass fraction of Si is limited to 0.8% to 2.0%. Exemplarily, the mass fraction of Si can be 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, etc.

[0030] Rare earth element Y can form rare earth compounds with elements such as N, O, and S in the alloy, which can effectively reduce the content of inclusions and make them evenly dispersed in the alloy. At the same time, adding rare earth element Y can inhibit the growth of alloy grains, make the grains tend to be refined, reduce the occurrence of cracks, and improve the plasticity and strength of the alloy at high temperature and room temperature. Rare earth element Y is also beneficial to improve the adhesion of the oxide film, and can improve the density of the oxide film, thereby improving the high temperature oxidation resistance of the alloy. Exemplarily, the mass fraction of Y can be 0.04%, 0.08%, 0.12%, 0.16%, 0.18%, 0.2%, etc.

[0031] Hf can inhibit nitridation precipitation at high temperature, and Y and Hf can form a stable nanocomposite phase, play a role in strengthening the grain boundary and increase the material use temperature. For example, the mass fraction of Hf can be 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, etc.

[0032] C, S and P are harmful to the high temperature oxidation resistance of the material and should be controlled at a lower limit.

[0033] Ni has the function of expanding austenite in the alloy, so increasing the mass fraction of Ni in the alloy can stabilize austenite and reduce the phase transition temperature of martensite to below room temperature, thereby ensuring the high temperature strength of the material. At the same time, controlling the nickel-iron ratio can ensure the stability of the material resistance temperature correction coefficient. For example, the mass fraction of Ni can be 51%, 51.4%, 51.8%, 52.2%, 52.6%, 53%, etc.

[0034] Fe is a matrix element. The specific content / content range of Fe can be obtained by the upper and lower limit formula of the component, that is:

[0035] The sum of the percentages of the contents of each component in a composition should be equal to 100%, and the content ranges of several components should meet the following conditions: the upper limit value of a component + the lower limit value of other components ≤ 100; the lower limit value of a component + the upper limit value of other components ≥ 100.

[0036] In some embodiments, the resistivity of the nickel-iron electrothermal alloy is 0.50 μΩ.mm -2 m -1 ~0.60μΩ.mm -2 m -1 .

[0037] Resistivity is an important parameter to measure the electrical conductivity of a material, which reflects the material's resistance to electric current. For electrothermal alloys, the size of the resistivity directly affects its heating performance and energy efficiency. In electrothermal alloys, the size of the resistivity is usually affected by many factors, including the chemical composition, microstructure, temperature, and processing technology of the alloy. By adjusting these factors, the resistivity of the electrothermal alloy can be accurately controlled to meet the needs of different application scenarios. The nickel-iron electrothermal alloy provided in the embodiment of the present application has a resistivity of 0.50μΩ.mm -2 m -1 ~0.60μΩ.mm -2 m -1 , which can ensure good electrical conductivity and generate sufficient heat when powered on. This alloy can be widely used in various electric heating elements, such as electric heaters, electric heating wires, electric heating plates, etc. In these applications, nickel-iron electric heating alloys can work stably and provide reliable heating effects. Exemplarily, the resistivity of nickel-iron electric heating alloys can be 0.50μΩ.mm -2 m -1 、0.52μΩ.mm -2 m -1 、0.54μΩ.mm -2 m -1 、0.56μΩ.mm -2 m -1 、0.58μΩ.mm -2 m -1 、0.60μΩ.mm -2 m -1 wait.

[0038] In some embodiments, the nickel-iron electrothermal alloy satisfies: in a 900° C. rapid life test, the rapid life value is >250 h.

[0039] The 900℃ rapid life test refers to an accelerated life test conducted in a high temperature environment of 900℃. The accelerated life test is a test method that converts the reliability information obtained in an accelerated environment beyond the normal stress level using statistical models related to the laws of physical failure on the basis of reasonable engineering and statistical assumptions, thereby obtaining a reproducible numerical estimate of the reliability characteristics of the product at the rated stress level. Carrying out a rapid life test under high temperature conditions of 900℃ can significantly accelerate the aging process of the product, shorten the test time, and improve the test efficiency. The embodiment of the present application uses a rapid life test to evaluate the durability of the electrothermal alloy at high temperatures. In a high temperature environment such as 900℃, the electrothermal alloy will be affected by multiple factors such as severe thermal stress, oxidation and corrosion, all of which will lead to a decrease in alloy performance and a shortened life. Therefore, a rapid life value of more than 250 hours means that the nickel-iron electrothermal alloy can operate stably for a long time under such extreme conditions, and is not prone to problems such as breakage, deformation or performance degradation. For example, in a 900° C. rapid life test of the nickel-iron electric heating alloy, the rapid life value may be 255 h, 260 h, 265 h, 270 h, 275 h, etc.

[0040] In summary, the embodiments of the present application innovatively propose a high-resistance and long-life nickel-iron electric heating alloy, which has the following advantages:

[0041] 1. The working temperature is significantly improved: By adding appropriate amounts of silicon, yttrium and hafnium elements, the working temperature range of the alloy has been significantly improved, making it suitable for higher temperature heating and electric heating elements.

[0042] 2. Resistivity optimization: The resistivity of the alloy has been finely controlled to meet the resistance value requirements of different application scenarios and improve the electrothermal efficiency and energy utilization.

[0043] 3. Expansion of application areas: Due to the excellent heat resistance, corrosion resistance and good mechanical properties of the alloy, its application areas have been greatly expanded, including but not limited to aerospace, electronics, chemicals and medical fields.

[0044] 4. Improved design flexibility and integration: Improved alloy performance makes product design more flexible, able to meet complex and changing application requirements, while improving product integration and reliability.

[0045] Therefore, the high-resistance and long-life nickel-iron electric heating alloy proposed in the embodiment of the present application has a unique chemical composition and excellent performance, which brings new technological breakthroughs and application prospects to the field of electric heating elements and materials.

[0046] Figure 1 A schematic flow chart of a method for preparing a high-resistance and long-life nickel-iron electrothermal alloy provided in an embodiment of the present application.

[0047] See also Figure 1 In a second aspect, an embodiment of the present application provides a method for preparing the high-resistance and long-life nickel-iron electrothermal alloy described in the first aspect, the method comprising:

[0048] S1, obtaining a nickel-iron electric heating alloy raw material containing the chemical composition;

[0049] S2, refining and pouring the nickel-iron electric heating alloy raw material in sequence to obtain a nickel-iron alloy steel ingot;

[0050] Molten steel is prepared according to the chemical composition. In the embodiment of the present application, raw materials such as nickel plate, pure iron, crystalline silicon, metallic chromium, and carbon particles are added to the crucible of the vacuum melting furnace, and the remaining micro-alloying element charges are added through the vacuum charging bin after they are completely melted. After the charging is completed, it is refined, and after refining and temperature adjustment, it is poured in an electric vacuum. After pouring, it is cooled with the furnace, and after breaking the vacuum, it is taken out of the furnace and demolded to form a nickel-iron alloy steel ingot.

[0051] In some embodiments, the pouring temperature is 1500°C to 1550°C.

[0052] The positive effect of limiting the pouring temperature to 1500℃~1550℃ is: ensuring smooth pouring while reducing alloy burning. If the pouring temperature is higher than 1550℃, it will accelerate the oxidation and burning of alloy elements to a certain extent; if the pouring temperature is lower than 1500℃, it will cause the molten steel to solidify during the pouring process, block the soup channel, and affect the quality of the steel ingot. Exemplarily, the pouring temperature can be 1500℃, 1505℃, 1510℃, 1515℃, 1520℃, 1525℃, 1530℃, 1535℃, 1540℃, 1545℃, 1550℃, etc.

[0053] S3, heating and rolling the nickel-iron alloy steel ingot in sequence to obtain a nickel-iron alloy wire rod;

[0054] In some embodiments, the heating temperature is 1120°C to 1180°C.

[0055] The positive effect of limiting the heating temperature to 1120℃~1180℃ is: ensuring that the inside and outside of the steel ingot reach the rolling start temperature. If the temperature is higher than 1180℃, it will cause surface oxidation, severe coarsening of the structure and overheating of the steel ingot to a certain extent, resulting in cracking during rolling; if the temperature is lower than 1120℃, it will cause the steel ingot to fail to reach the rolling start temperature to a certain extent, the thermoplasticity of the material will deteriorate, and cracking will occur during deformation. Exemplarily, the heating temperature can be 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, etc.

[0056] In some embodiments, the heating time is 90 min to 400 min.

[0057] The positive effect of limiting the heating time to 90min to 400min is to ensure uniform heating inside and outside the ingot. If the time is longer than 400min, the ingot structure will grow and the surface will oxidize to a certain extent; if the time is shorter than 90min, the internal temperature of the ingot will not reach the set temperature to a certain extent, and the core will crack during rolling. For example, the heating time can be 90min, 130min, 170min, 210min, 250min, 290min, 330min, 370min, 400min, etc.

[0058] In some embodiments, the starting temperature of the rolling is 1120°C to 1180°C.

[0059] The positive effect of limiting the rolling temperature to 1120℃~1180℃: the thermoplasticity in this temperature range is good, which is conducive to hot working deformation. If the rolling temperature is higher than 1180℃, it will cause surface oxidation and serious coarsening of the alloy to a certain extent, leading to rolling cracking; if the rolling temperature is lower than 1120℃, it will make the alloy thermoplastic to a certain extent, leading to cracking during deformation. Exemplarily, the rolling temperature can be 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, etc.

[0060] S4, sequentially subjecting the nickel-iron alloy wire rod to heat treatment, drawing and annealing to obtain a nickel-iron electrothermal alloy.

[0061] The rolled nickel-iron alloy wire rod is water-cooled after heat treatment, and then the surface oxide film of the nickel-iron alloy wire rod is removed to ensure the quality of subsequent processing. The treated nickel-iron alloy wire rod is then drawn to form a drawn cold finished product. The drawn cold finished product is then subjected to atmosphere protection annealing treatment to eliminate processing stress and dislocation, and improve the mechanical properties of the finished product, and finally a nickel-iron electrothermal alloy is obtained for the production of heating elements.

[0062] In some embodiments, the temperature of the heat treatment is 950° C. to 1050° C., and the holding time of the heat treatment is 2 h to 4 h.

[0063] The purpose of this step is to make the wire rod structure uniform and eliminate work hardening. For example, the heat treatment temperature is 950°C, 970°C, 990°C, 1010°C, 1030°C, 1050°C, etc.; the heat treatment holding time can be 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0064] In some embodiments, the annealing treatment is performed at a temperature of 1000°C to 1150°C.

[0065] The positive effect of limiting the annealing temperature to 1000℃~1150℃: within this temperature range, it is beneficial to eliminate processing stress and dislocation, and improve the mechanical properties of the finished product. If the annealing temperature is higher than 1150℃, it will cause the internal structure of the alloy to be coarse to a certain extent; if the annealing temperature is lower than 1000℃, it will cause the material strength to be too high and the material processing performance to deteriorate to a certain extent. Exemplarily, the annealing temperature can be 1000℃, 1030℃, 1060℃, 1090℃, 1120℃, 1150℃, etc.

[0066] The product prepared by the method for preparing high-resistance and long-life nickel-iron electrothermal alloy is the above-mentioned high-resistance and long-life nickel-iron electrothermal alloy. Since the method for preparing high-resistance and long-life nickel-iron electrothermal alloy adopts part or all of the technical solutions of the high-resistance and long-life nickel-iron electrothermal alloy embodiment, it at least has all the beneficial effects brought by the technical solutions of the high-resistance and long-life nickel-iron electrothermal alloy, which will not be repeated here one by one.

[0067] The present application is further described below in conjunction with specific embodiments. The experimental methods in the following embodiments that do not specify specific conditions are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions, or conditions recommended by the manufacturer.

[0068] Example 1

[0069] The chemical composition of nickel-iron electric heating alloy includes: C 0.02%, Si 1.25%, S 0.001%, Cr 0.4%, P0.007%, Ni 52.1%, Y 0.2%, Hf 0.02%, Fe.

[0070] The method for preparing the nickel-chromium-iron alloy mainly comprises the following steps:

[0071] 1. Add nickel plate, pure iron, crystalline silicon, metal chromium and carbon particles into the crucible of vacuum melting furnace, and evacuate the furnace to make the vacuum degree in the furnace 8Pa. Apply electricity to melt until all the materials are melted and the molten pool is flat and clean. After the molten pool is flat and clean, add yttrium iron and metal hafnium through the vacuum charging bin. After the addition is completed, refine at a refining temperature of 1600℃, adjust the temperature after refining, and then cast in vacuum with electricity at a pouring temperature of 1500℃; after pouring, cool with the furnace, break the vacuum and take out of the furnace, demold to form alloy steel ingot.

[0072] 2. The obtained alloy steel ingot is heated in a heating furnace at a heating temperature of 1150° C. for a heating time of 180 min, and then rolled at a starting rolling temperature of 1150° C. to obtain a nickel-iron alloy wire rod.

[0073] 3. After rolling, the wire rod is heat treated by keeping it at 1030℃ for 3 hours and then cooling it with water.

[0074] 4. After heat treatment, soak the wire rod in molten sodium hydroxide at 700℃ for 3 minutes and then rinse with water. Then soak it in sulfuric acid with a concentration of 180g / L for 30 minutes, rinse the surface residue with water, and dry it.

[0075] 5. The cleaned wire rod is drawn to form a drawn cold finished product, and the finished product is annealed in an atmosphere-protected continuous annealing furnace at a temperature of 1050°C to form an annealed finished product for the production of heating elements.

[0076] Example 2

[0077] The chemical composition of nickel-iron electric heating alloy includes: C 0.02%, Si1.85%, S 0.001%, Cr 0.2%, P0.007%, Ni 51.8%, Y 0.05%, Hf 0.07%, Fe.

[0078] The method for preparing the nickel-chromium-iron alloy mainly comprises the following steps:

[0079] 1. Add nickel plate, pure iron, crystalline silicon, metal chromium and carbon particles into the crucible of vacuum melting furnace, and evacuate the furnace to make the vacuum degree in the furnace 7Pa. Apply electricity to melt until all the materials are melted and the molten pool is flat and clean. After the molten pool is flat and clean, add yttrium iron and metal hafnium through the vacuum charging bin. After the addition is completed, refine at a refining temperature of 1600℃, adjust the temperature after refining, and then cast in vacuum with electricity at a pouring temperature of 1510℃; after pouring, cool with the furnace, break the vacuum and take out of the furnace, demold to form alloy steel ingot.

[0080] 2. The obtained alloy steel ingot is heated in a heating furnace at a heating temperature of 1150° C. for a heating time of 210 min, and then rolled at a starting rolling temperature of 1150° C. to obtain a nickel-iron alloy wire rod.

[0081] 3. After rolling, the wire rod is heat treated by keeping it at 1050°C for 3.5 hours and then cooling it with water.

[0082] 4. After heat treatment, soak the wire rod in molten sodium hydroxide at 700℃ for 3.5 minutes and then rinse with water. Then soak it in sulfuric acid with a concentration of 181g / L for 38 minutes, rinse the surface residue with water, and dry it.

[0083] 5. The cleaned wire rod is drawn to form a drawn cold finished product, and the finished product is annealed in an atmosphere-protected continuous annealing furnace at a temperature of 1033°C to form an annealed finished product for the production of heating elements.

[0084] Example 3

[0085] The chemical composition of nickel-iron electric heating alloy includes: C 0.02%, Si 0.85%, S 0.001%, Cr 0.75%, P0.007%, Ni 52.5%, Y 0.1%, Hf 0.04%, Fe.

[0086] The method for preparing the nickel-chromium-iron alloy mainly comprises the following steps:

[0087] 1. Add nickel plate, pure iron, crystalline silicon, metal chromium and carbon particles into the crucible of vacuum melting furnace, and evacuate the furnace to make the vacuum degree in the furnace 10Pa. Apply electricity to melt until all the materials are melted and the molten pool is flat and clean. After the molten pool is flat and clean, add yttrium iron and metal hafnium through the vacuum charging bin. After the addition is completed, refine at a refining temperature of 1600℃, adjust the temperature after refining, and then cast in vacuum with electricity at a pouring temperature of 1530℃; after pouring, cool with the furnace, break the vacuum and take out of the furnace, demould to form alloy steel ingot.

[0088] 2. The obtained alloy steel ingot is heated in a heating furnace at a heating temperature of 1155° C. for a heating time of 190 min, and then rolled at a starting rolling temperature of 1155° C. to obtain a nickel-iron alloy wire rod.

[0089] 3. After rolling, the wire rod is heat treated by keeping it at 1040℃ for 4 hours and then cooling it with water.

[0090] 4. After heat treatment, soak the wire rod in molten sodium hydroxide at 700℃ for 5 minutes and then rinse with water. Then soak it in sulfuric acid with a concentration of 185g / L for 40 minutes, rinse the surface residue with water, and dry it.

[0091] 5. The cleaned wire rod is drawn to form a drawn cold finished product, and the finished product is annealed in an atmosphere-protected continuous annealing furnace at a temperature of 1050°C to form an annealed finished product for the production of heating elements.

[0092] Comparative Example 1

[0093] The chemical composition of nickel-iron electric heating alloy includes: C 0.02%, Si 0.28%, S 0.001%, P 0.007%, Ni52.1%, Y 0.2%, Hf 0.02%, Fe.

[0094] The method for preparing the nickel-iron alloy mainly comprises the following steps:

[0095] 1. Add nickel plate, pure iron, crystalline silicon and carbon particles into the crucible of vacuum melting furnace, and evacuate the furnace to make the vacuum degree in the furnace 5Pa. Apply electricity to melt until all the materials are melted and the molten pool is flat and clean. After the molten pool is flat and clean, add yttrium iron and metal hafnium through the vacuum charging bin. After the addition is completed, refine at a refining temperature of 1600℃, adjust the temperature after refining, and then cast in vacuum with electricity at a pouring temperature of 1520℃; after pouring, cool with the furnace, break the vacuum and take out of the furnace, demold to form alloy rods.

[0096] 2. The alloy rods are used as consumable electrodes and purified in a single-phase electroslag remelting furnace to obtain alloy ingots. In order to ensure the rare earth recovery rate in the purified alloy, Y2O3 is added to the purified slag, and the mass ratio of the refined slag is Y2O3:CaO:CaF2=15:5:80, and each furnace of refined slag is 5kg.

[0097] 3. The obtained alloy ingot is heated in a heating furnace at a heating temperature of 1160° C. for a heating time of 180 min, and then rolled at a starting rolling temperature of 1160° C. to obtain a nickel-iron alloy wire rod.

[0098] 4. After rolling, the wire rod is heat treated by keeping it at 1050℃ for 3 hours and then cooling it with water.

[0099] 5. After heat treatment, soak the wire rod in molten sodium hydroxide at 700℃ for 4 minutes and then rinse with water. Then soak it in sulfuric acid with a concentration of 185g / L for 35 minutes, rinse the surface residue with water, and dry it.

[0100] 6. The cleaned wire rod is drawn to form a drawn cold finished product, and the finished product is annealed in an atmosphere-protected continuous annealing furnace at a temperature of 1030°C to form an annealed finished product for the production of heating elements.

[0101] Comparative Example 2

[0102] The chemical composition of nickel-iron electric heating alloy includes: C 0.02%, Si 0.5%, S 0.001%, P 0.007%, Ni52.1%, Fe.

[0103] The method for preparing the nickel-iron alloy mainly comprises the following steps:

[0104] 1. Add nickel plate, pure iron and carbon particles into the crucible of vacuum melting furnace, and evacuate the furnace to make the vacuum degree in the furnace 4Pa. Apply electricity to melt until all the materials are melted and the molten pool is flat and clean. After the molten pool is flat and clean, add crystalline silicon through the vacuum charging bin. After the charging is completed, it is refined at a refining temperature of 1600℃. After refining, the temperature is adjusted, and then vacuum casting is carried out with electricity at a casting temperature of 1530℃. After casting, it is cooled with the furnace, and the vacuum is broken and the furnace is taken out and demolded to form an alloy steel ingot.

[0105] 2. The obtained alloy steel ingot is heated in a heating furnace at a heating temperature of 1150° C. for a heating time of 200 min, and then rolled at a starting rolling temperature of 1150° C. to obtain a nickel-iron alloy wire rod.

[0106] 3. After rolling, the wire rod is heat treated by keeping it at 1050℃ for 3 hours and then cooling it with water.

[0107] 4. After heat treatment, soak the wire rod in molten sodium hydroxide at 700℃ for 4 minutes and then rinse with water. Then soak it in sulfuric acid with a concentration of 180g / L for 40 minutes, rinse the surface residue with water, and dry it.

[0108] 5. The cleaned wire rod is drawn to form a drawn cold finished product, and the finished product is annealed in an atmosphere-protected continuous annealing furnace at a temperature of 1050°C to form an annealed finished product for the production of heating elements.

[0109] The resistivity of the bright alloy wire with a specification of 0.8 mm in the above examples and comparative examples was measured at 20°C, and a rapid life test was performed at 900°C. The results are shown in Table 1. The oxidation weight gain test was performed at 600°C, and the experimental results are shown in graphical form. Figure 2 middle.

[0110] Table 1 Fast life and resistivity

[0111]

[0112]

[0113] As shown in Table 1, the chemical composition and preparation process of the embodiment are within the required range of the present invention. At 900°C, the fast life value can reach more than 250h. The resistivity at 20°C is 0.50μΩ.mm -2 m -1 ~0.60μΩ.mm -2 m -1 .

[0114] The oxidation weight gain test at 600℃ is intended to evaluate the oxidation resistance of the alloy at high temperatures. Figure 2 It can be seen that the alloy wire of the embodiment has good oxidation resistance.

[0115] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0116] The working temperature range of the nickel-iron electric heating alloy provided by the embodiment of the present invention is expanded from the original 0-150° C. to 0-500° C., which greatly expands its scope of application.

[0117] The nickel-iron electric heating alloy provided in the embodiment of the present invention has a resistance correction coefficient that meets the PTC performance requirements while ensuring mechanical properties, making it more suitable for use in a limited design space, thereby improving the design flexibility and integration of the product.

[0118] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A high-resistance and long-life nickel-iron electric heating alloy, wherein the chemical composition of the nickel-iron electric heating alloy comprises, by mass fraction: C： 0.01%~0.03%, Si: 0.8%~2.0%, Cr≤0.8%, S≤0.003%, P≤0.020%, Ni: 51%~53%, Y: 0.04%~0.2%, Hf: 0.02%~0.07%, and matrix element Fe.

2. The nickel-iron electric heating alloy according to claim 1, characterized in that: The resistivity of the nickel-iron electric heating alloy is 0.50 μΩ.mm -2 m -1 ~0.60μΩ.mm -2 m -1 .

3. The nickel-iron electric heating alloy according to claim 1, characterized in that: The nickel-iron electric heating alloy meets the following requirements: in a 900° C. rapid life test, the rapid life value is greater than 250 h.

4. A method for preparing a high-resistance and long-life nickel-iron electrothermal alloy according to any one of claims 1 to 3, characterized in that: The method comprises: Obtaining a nickel-iron electric heating alloy raw material containing the chemical composition; Refining and pouring the nickel-iron electric heating alloy raw material in sequence to obtain a nickel-iron alloy steel ingot; The nickel-iron alloy steel ingot is sequentially heated and rolled to obtain a nickel-iron alloy wire rod; The nickel-iron alloy wire rod is subjected to heat treatment, drawing and annealing treatment in sequence to obtain the nickel-iron electrothermal alloy.

5. The method according to claim 4, characterized in that The pouring temperature is 1500°C to 1550°C.

6. The method according to claim 4, characterized in that The heating temperature is 1120°C to 1180°C.

7. The method according to claim 4, characterized in that The heating time is 90 min to 400 min.

8. The method according to claim 4, characterized in that The rolling start temperature is 1120°C to 1180°C.

9. The method according to claim 4, characterized in that The temperature of the heat treatment is 950° C. to 1050° C., and the insulation time of the heat treatment is 2 h to 4 h.

10. The method according to claim 4, characterized in that The annealing treatment is performed at a temperature of 1000°C to 1150°C.

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