High nickel alloy and manufacturing method thereof

Abstract

This disclosure relates to a high-nickel alloy and a method for manufacturing the same. The high-nickel alloy comprises 95 to 99.3% by weight nickel, 0.15 to 3% by weight titanium, 0.15 to 3% by weight niobium, no more than 0.35% by weight silicon, no more than 0.35% by weight manganese, no more than 0.35% by weight iron, no more than 0.15% by weight carbon, and unavoidable impurities.

Description

Technical Field

[0001] This disclosure relates to a high-nickel alloy and a method for manufacturing the high-nickel alloy, and more particularly to a high-nickel alloy comprising titanium and niobium and a method for manufacturing the same. Prior Technology

[0002] Industrial high-nickel alloys (nickel content of 95% by weight or higher) are typically suitable for temperature environments below 315°C and can be used as materials for equipment such as pipelines or tanks. They are also applied in caustic alkaline environments such as those used in the food, synthetic fiber, and chlor-alkali industries. To ensure the purity of the manufactured products, the corrosion resistance and mechanical properties of high-nickel alloy products in strongly alkaline environments such as sodium hydroxide or potassium hydroxide are of paramount importance.

[0003] However, existing high-nickel alloys suffer from insufficient strength due to softening at high temperatures (e.g., above 600°C), and are prone to graphitization and / or carbon precipitation at grain boundaries. This leads to embrittlement, loss of ductility, low strength, and poor corrosion resistance, resulting in insufficient mechanical and corrosion-resistant properties and susceptibility to cracking. Therefore, there is an urgent need to provide a high-nickel alloy to solve the above problems. Summary of the Invention

[0004] One aspect of this disclosure is a high-nickel alloy with a specific content of titanium and niobium. This high-nickel alloy can be used in high-temperature caustic alkali industrial environments, exhibiting superior high-temperature strength, inhibiting graphitization of the high-nickel alloy, preventing embrittlement at high temperatures, further preventing cracking, and demonstrating excellent corrosion resistance.

[0005] This disclosure provides at least one embodiment of a high-nickel alloy. Based on 100% by weight of the total weight of the high-nickel alloy, the high-nickel alloy comprises 95% to 99.3% by weight of nickel, 0.15% to 3% by weight of titanium, 0.15% to 3% by weight of niobium, no more than 0.35% by weight of silicon, no more than 0.35% by weight of manganese, no more than 0.35% by weight of iron, no more than 0.15% by weight of carbon, and unavoidable impurities, wherein the impurities include cobalt, chromium, copper, aluminum, phosphorus, sulfur, or a combination of the above elements.

[0006] In at least one embodiment of this disclosure, the total content of titanium and niobium is from 0.3% to 5% by weight.

[0007] In at least one embodiment of this disclosure, the ratio of titanium to niobium is 0.1 to 10.

[0008] In at least one embodiment of this disclosure, the ratio of titanium to niobium is 0.4 to 2.5.

[0009] In at least one embodiment of this disclosure, the precipitates of the high-nickel alloy comprise titanium niobium carbide, titanium carbonitride, or a combination thereof, and the size of the precipitates within the grains of the high-nickel alloy is 0.5 µm to 5 µm.

[0010] In at least one embodiment of this disclosure, the precipitates of the high-nickel alloy comprise titanium niobium carbide, titanium carbonitride, or a combination thereof, and the size of the precipitates on the grain boundaries of the high-nickel alloy is 20 nm to 300 nm.

[0011] In at least one embodiment of this disclosure, at 25°C, the high-nickel alloy has a tensile strength of at least 485 MPa, a yield strength of at least 312 MPa, and an elongation of at least 22%.

[0012] In at least one embodiment of this disclosure, at 650°C, the high-nickel alloy has a tensile strength of at least 292 MPa, a yield strength of at least 61 MPa, and an elongation of at least 82%.

[0013] In at least one embodiment of this disclosure, at 850°C, the high-nickel alloy has a tensile strength of at least 101 MPa, a yield strength of at least 52 MPa, and an elongation of at least 95%.

[0014] This disclosure provides at least one embodiment of a method for manufacturing a high-nickel alloy, comprising the following steps: providing an alloy billet, wherein the alloy billet comprises, by weight percentage (100%), 95% to 99.3% nickel, 0.15% to 3% titanium, 0.15% to 3% niobium, no more than 0.35% silicon, no more than 0.35% manganese, no more than 0.35% iron, no more than 0.15% carbon, and unavoidable impurities, wherein the impurities include cobalt, chromium, copper, aluminum, phosphorus, sulfur, or a combination of the above elements; and smelting the alloy billet to obtain a high-nickel alloy. Simple Explanation of the Diagram

[0015] The nature of this disclosure will be fully understood when read in conjunction with the accompanying drawings. For clarity of explanation, the dimensions of the features may be increased or decreased as desired. Figure 1 is a flowchart of a method for manufacturing a high-nickel alloy according to the present disclosure. Figure 2A is a scanning electron microscope image of the high-nickel alloy of Experimental Example 1 according to the present disclosure after a corrosion test at 850°C. Figure 2B shows the energy-scattered X-ray spectrum of the precipitates of the high-nickel alloy in Experimental Example 1 according to this disclosure after a corrosion test at 850°C. Figure 3A is a scanning electron microscope image of the high-nickel alloy of Comparative Example 1 according to the present disclosure after a corrosion test at 850°C. Figure 3B is a scanning electron microscope image of the high-nickel alloy of Experimental Example 1 according to this disclosure after a corrosion test at 850°C. Implementation

[0016] The following detailed discussion of the manufacture and use of embodiments of this disclosure is provided. However, it is understood that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific situations. The specific embodiments discussed are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0017] In this document, the term "from one value to another" is a concise way of indicating a range to avoid listing all the values ​​within that range in the specification. Therefore, the description of a particular range of values ​​encompasses any value within that range and the smaller range of values ​​defined by that value, just as if the arbitrary value and the smaller range of values ​​were explicitly stated in the specification. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0018] This disclosure provides a high-nickel alloy. Based on 100% by weight of the total weight of the high-nickel alloy, the high-nickel alloy comprises 95% to 99.3% by weight nickel, 0.15% to 3% by weight titanium, 0.15% to 3% by weight niobium, not more than 0.35% by weight silicon, not more than 0.35% by weight manganese, not more than 0.35% by weight iron, not more than 0.15% by weight carbon, and unavoidable impurities, wherein the impurities include cobalt, chromium, copper, aluminum, phosphorus, sulfur, or combinations thereof. It should be noted that "unavoidable impurities" in this document refers to the absence of any additional addition of the aforementioned trace elements.

[0019] When the content of each element in the high-nickel alloy is within the above range, graphitization of the high-nickel alloy can be suppressed in a caustic alkali industrial environment at high temperature (e.g., 600°C to 900°C), and good mechanical strength can be maintained. Therefore, the high-nickel alloy can be prevented from becoming embrittled at high temperature and further prevented from cracking, and it also has good corrosion resistance.

[0020] In some embodiments, the high-nickel alloy comprises 96, 97, 98, or 99% by weight of nickel. When the nickel content is less than 95% by weight, the corrosion resistance of the high-nickel alloy decreases. When the nickel content is greater than 99.3% by weight, it does not significantly improve the corrosion resistance of the high-nickel alloy, the mechanical properties of the high-nickel alloy may be insufficient, and its high-temperature corrosion resistance is poor.

[0021] In some embodiments, the high-nickel alloy comprises 0.2, 0.5, 1, 1.5, 2, or 2.5 weight percent titanium. Titanium has a solid solution strengthening effect. When the titanium content is less than 0.15 weight percent, the grain boundary migration of the high-nickel alloy cannot be effectively restrained during its formation, resulting in poor grain growth inhibition and thus failing to improve the mechanical properties of the high-nickel alloy. Due to the high price of titanium raw materials, when the titanium content is greater than 3 weight percent, the raw material cost increases, and the grain size in the obtained high-nickel alloy becomes too large, resulting in poor hot workability (e.g., rolling or forging) and insufficient mechanical properties.

[0022] In some embodiments, the high-nickel alloy contains 0.2, 0.5, 1, 1.5, 2, or 2.5 weight percent niobium. Niobium has a solid solution strengthening effect. When the niobium content is less than 0.15 weight percent, the grain boundary migration of the high-nickel alloy cannot be effectively restrained during the formation of the high-nickel alloy, resulting in poor grain growth inhibition and thus failing to improve the mechanical properties of the high-nickel alloy. Due to the high price of niobium raw materials, when the niobium content is greater than 3 weight percent, the raw material cost increases, and the grain size in the obtained high-nickel alloy will be too large, resulting in poor hot workability (e.g., rolling or forging) and insufficient mechanical properties.

[0023] In some embodiments, the high-nickel alloy contains 0.1, 0.2, or 0.3% by weight of silicon. Silicon has a solid solution strengthening effect. Because silicon readily forms SiO2 or complex oxides with oxygen, but its solubility in solid solutions is low and it easily promotes the formation of brittle phases, when the silicon content is greater than 0.35% by weight, the weldability and hot workability of the smelted alloy are poor, and its corrosion resistance in alkaline environments is also poor.

[0024] In some embodiments, the high-nickel alloy contains 0.1, 0.2, or 0.3% by weight of manganese. Since manganese readily forms low-melting-point compounds with S, O, and C, which reduce high-temperature mechanical properties and are detrimental to corrosion resistance, when the manganese content is greater than 0.35% by weight, the smelted alloy exhibits poor mechanical properties and corrosion resistance in alkaline environments.

[0025] In some embodiments, the high-nickel alloy contains 0.1, 0.2, or 0.3% by weight of iron. Since increasing the iron content reduces the solid solution strengthening effect, leading to a decrease in material strength, and because iron is more easily oxidized and less resistant to corrosion, the resulting alloy exhibits poor mechanical properties and corrosion resistance when the iron content exceeds 0.35% by weight.

[0026] In some embodiments, the high-nickel alloy contains 0.11, 0.12, 0.13, or 0.14% carbon by weight. When the carbon content is greater than 0.15% by weight, it will directly lead to intergranular graphitization, which easily promotes the precipitation of excessive carbides and causes grain boundary embrittlement, resulting in poor high-temperature mechanical properties and ductility of the alloy.

[0027] In some embodiments, the total content of titanium and niobium is from 0.3 to 5% by weight, for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5% by weight. When the total content of titanium and niobium is within the above range, it is beneficial to suppress graphitization during the formation of the high-nickel alloy and obtain the high-nickel alloy of this invention, which has good corrosion resistance and mechanical strength at both room temperature and high temperature.

[0028] In some embodiments, the titanium to niobium content ratio is 0.1 to 10, for example 0.1 to 8, 0.4 to 2.5, or 1 to 2.2. When the titanium to niobium content ratio is within the above range, it is beneficial to suppress graphitization during the formation of the high-nickel alloy and obtain the high-nickel alloy of this invention that has good corrosion resistance and mechanical strength at both room temperature and high temperature.

[0029] In some embodiments, the precipitates of the high-nickel alloy comprise titanium niobium carbide, titanium niobium carbonitride, or a combination thereof. It should be noted that "titanium niobium carbide (Nb, Ti)C" and "titanium niobium carbonitride (Nb, Ti)CN" as used herein can be understood as carbides of titanium niobium. "Titanium niobium carbide (Nb, Ti)C" and "titanium niobium carbonitride (Nb, Ti)CN" can also be referred to as secondary phases, which can strengthen the high-nickel alloy and stabilize carbon to suppress graphitization. It is understood that "titanium niobium carbide" herein includes niobium carbide, titanium carbide, titanium niobium carbide, or a combination thereof, while "titanium niobium carbonitride" herein includes niobium carbonitride, titanium carbonitride, titanium niobium carbonitride, or a combination thereof. Furthermore, since titanium niobium carbide typically incorporates nitrogen to form titanium niobium carbonitride, the precipitates of the high-nickel alloy also include titanium niobium carbonitride. Since niobium and titanium are dissolved in high-nickel alloys, niobium titanium carbide and niobium carbonitride titanium can also be understood as "mixed solid solutions".

[0030] In some embodiments, the size of the precipitates (titanium niobium carbide or titanium carbonitride) within the grains of the high-nickel alloy is 0.5 µm to 5 µm, for example, 1 µm, 2 µm, 3 µm, or 4 µm. In some embodiments, the size of the precipitates (titanium niobium carbide or titanium carbonitride) at the grain boundaries of the high-nickel alloy is 20 nm to 300 nm, for example, 80 nm, 100 nm, 150 nm, 200 nm, or 250 nm. When the sizes of the precipitates within the grains and the precipitates at the grain boundaries are within the above ranges, it is advantageous to obtain the high-nickel alloy of this invention, which exhibits good corrosion resistance and mechanical strength at both room temperature and high temperature.

[0031] In some embodiments, at 25°C, the high-nickel alloy has a tensile strength of at least 485 MPa, a yield strength of at least 312 MPa, and an elongation of at least 22%. When the mechanical strength of the high-nickel alloy is within the above range, it is beneficial to prevent the high-nickel alloy from becoming brittle at room temperature.

[0032] In some embodiments, at 650°C, the high-nickel alloy has a tensile strength of at least 292 MPa, a yield strength of at least 61 MPa, and an elongation of at least 82%. When the mechanical strength of the high-nickel alloy is within the above range, it is beneficial to prevent the high-nickel alloy from becoming embrittled in high-temperature environments.

[0033] In some embodiments, at 850°C, the high-nickel alloy has a tensile strength of at least 101 MPa, a yield strength of at least 52 MPa, and an elongation of at least 95%. When the mechanical strength of the high-nickel alloy is within the above range, it is beneficial to prevent the high-nickel alloy from becoming embrittled in high-temperature environments.

[0034] Figure 1 is a flowchart of a method 100 for manufacturing a high-nickel alloy according to the present disclosure. In the manufacturing method 100, firstly, an alloy blank is provided, as shown in step 110 of Figure 1. In some embodiments, the alloy blank contains, by weight percentage (100%), 95% to 99.3% nickel, 0.15% to 3% titanium, 0.15% to 3% niobium, no more than 0.35% silicon, no more than 0.35% manganese, no more than 0.35% iron, no more than 0.15% carbon, and unavoidable impurities, wherein the impurities include cobalt, chromium, copper, aluminum, phosphorus, sulfur, or a combination of the above elements.

[0035] The effects of the types and contents of elements in the aforementioned alloy blanks on the graphitization, corrosion resistance, and mechanical strength (including tensile strength, yield strength, and elongation) of high-nickel alloys have been described above and will not be repeated here.

[0036] Next, the alloy billet is melted to obtain a high-nickel alloy, as shown in steps 120 and 130 of Figure 1. The melting method disclosed herein is not limited to a specific method. The melting method may be, for example, melting in a fuel-heated furnace, melting in an electric arc furnace (EAF), melting in a vacuum induction furnace (VIM), melting in a vacuum arc furnace (VAM), or a combination thereof, to obtain a high-nickel alloy in the form of ingots or continuously cast billets.

[0037] In some embodiments, a refining process may be selectively performed after the melting process to increase the uniformity of the alloy composition and microstructure. Refining methods may include, for example, argon oxygen decarburization (AOD), vacuum oxygen decarburization (VOD), electroslag remelting (ESR), vacuum arc remelting (VAR), or a combination thereof. The refined alloy billet has a uniform microstructure and is free of large inclusions (e.g., oxides or sulfides), exhibiting good machinability and thus suitable for subsequent forming and processing. In some embodiments, depending on the surface condition of the alloy billet, surface treatment steps may be performed, such as cutting, grinding, or peeling, to ensure the surface quality of the cast billet before processing. The obtained cast billet can be produced into forgings, plates, coils, bars, wires, tubes, and other products through hot or cold working methods such as forging, rolling, drawing, tube forming, and welding, facilitating various subsequent industrial applications.

[0038] The following comparative and experimental examples are used to illustrate the application of this disclosure, but they are not intended to limit the content of this disclosure. Anyone skilled in this art may make various modifications and embellishments without departing from the spirit and scope of this disclosure.

[0039] Comparative Example 1

[0040] In Comparative Example 1, an alloy billet was provided. Based on 100% by weight of the total weight of the alloy billet, the alloy billet contained 99.46% by weight of nickel, 0.11% by weight of silicon, 0.1% by weight of manganese, 0.12% by weight of iron, 0.01% by weight of carbon, and unavoidable impurities totaling no more than 0.3% by weight, wherein the impurities included cobalt, chromium, copper, aluminum, phosphorus, sulfur, or combinations thereof. The elemental contents of the alloy billet are shown in Table 1.

[0041] Table 1

[0042] Subsequently, the alloy blank of Comparative Example 1 was subjected to non-vacuum electric furnace melting (EAF) and argon oxygen blowing decarburization (AOD) to obtain the high-nickel alloy of Comparative Example 1.

[0043] Comparative Example 1 and Experimental Examples 1 to 4

[0044] Comparative Example 1 and Experimental Examples 1 to 4 were conducted in a similar manner to Comparative Example 1. The difference was that the elemental content, smelting method, and / or refining method of the alloy billet were changed in Comparative Example 1 and Experimental Examples 1 to 4.

[0045] In detail, Comparative Examples 1 and 2 did not contain titanium or niobium, while Experimental Examples 1 to 4 all contained titanium and niobium. The elemental contents of the alloy billets for each example are shown in Table 1 above. Comparative Examples 2 and 3 used the same melting and refining methods as Comparative Example 1, namely EAF and AOD. Experimental Examples 1, 2, and 4 used a vacuum induction furnace (VIM) melting method and an electroslag remelting (ESR) or vacuum arc remelting (VAR) refining method.

[0046] The high-nickel alloy ingots of Comparative Examples 1 to 2 and Experimental Examples 1 to 4 were forged and rolled to produce plates with a thickness of 7 mm. After cutting, their mechanical properties and corrosion resistance at 25°C, 650°C and 850°C were tested respectively. The evaluation results are shown in Tables 2 and 3 below.

[0047] Table 2

[0048] Table 3

[0049] Evaluation method

[0050] 1. Mechanical properties at 25°C (room temperature)

[0051] The mechanical properties at 25°C mentioned herein include tests for tensile strength (TS), yield strength (YS), and elongation (EL). The tensile strength, yield strength, and elongation were measured according to the standard method ASTM (American Society for Testing and Materials) E21 high-temperature tensile test to measure the mechanical properties of high-nickel alloys in Comparative Examples 1-2 and Experimental Examples 1-4 at 25°C. The measurement results are shown in Table 2. Table 2 shows that, compared to Comparative Examples 1-2, Experimental Examples 1-4 exhibited better tensile strength and yield strength, with a tensile strength of at least 485 MPa and a yield strength of at least 312 MPa.

[0052] 2. Mechanical properties at 650°C

[0053] The mechanical properties measured at 650°C as described herein include tests for tensile strength, yield strength, and elongation. These tensile strength, yield strength, and elongation are measured at 650°C according to the standard method ASTM E21 high-temperature tensile test to measure the mechanical properties of high-nickel alloys in Comparative Examples 1-2 and Experimental Examples 1-4 at 650°C. The results are shown in Table 2. Table 2 shows that, compared to Comparative Examples 1-2, Experimental Examples 1-4 exhibit significantly better tensile strength, yield strength, and elongation, with a tensile strength of at least 292 MPa, a yield strength of at least 61 MPa, and an elongation of at least 82%.

[0054] 3. Mechanical properties at 850°C

[0055] The mechanical properties at 850°C mentioned herein include tests for tensile strength, yield strength, and elongation. These tensile strength, yield strength, and elongation are measured at 850°C according to the standard method ASTM E21 high-temperature tensile test to measure the mechanical properties of high-nickel alloys in Comparative Examples 1-2 and Experimental Examples 1-4 at 850°C. The measurement results are shown in Table 2. Table 2 shows that, compared to Comparative Examples 1-2, Experimental Examples 1-4 exhibit significantly better tensile strength, yield strength, and elongation, with a tensile strength of at least 101 MPa, a yield strength of at least 52 MPa, and an elongation of at least 95%.

[0056] Furthermore, compared to Experimental Examples 2 and 3, Experimental Examples 1 and 4 exhibited superior mechanical properties. This suggests that when the titanium to niobium content ratio is approximately 2, the resulting high-nickel alloy possesses better mechanical properties.

[0057] Generally, alloys with a tensile strength of 90 MPa or higher and a yield of 50 MPa or higher are suitable for use as materials for equipment subjected to conventional industrial stress at specific temperatures, thus preventing rapid deformation and failure. As shown in Table 2, even at 850°C, Experimental Examples 1 to 4 still meet the requirements for materials used in equipment subjected to conventional industrial stress, making them suitable for high-temperature equipment. Specifically, because Experimental Examples 1 to 4 incorporate titanium and niobium, which have solid solution strengthening properties, and generate secondary phases of niobium-titanium carbide and niobium-carbonitrile-titanium carbonitride, the high-nickel alloys are strengthened, and carbon is stabilized to suppress graphitization.

[0058] Furthermore, since the secondary phase and the Wostian iron phase substrate have a coherent interface, the pinning effect can be used to restrain grain boundary migration, thereby inhibiting grain growth and refining the grains to further improve the mechanical strength of the material.

[0059] 4. Corrosion resistance test

[0060] The corrosion resistance tests described herein involved immersing the high-nickel alloys of Comparative Examples 1-2 and Experimental Examples 1-4 in different solutions for extended periods and measuring their corrosion weight loss. Specifically, the high-nickel alloys of Comparative Examples 1-2 and Experimental Examples 1-4 were immersed in boiling 50% KOH solution, molten 50% KOH solution at 650°C, and molten 50% KOH solution at 850°C for 168 hours, 5000 hours, and 5000 hours, respectively, to measure the corrosion resistance of the high-nickel alloys at different temperatures. The measurement results are shown in Table 3. The corrosion rate is expressed in mils per year (mpy). A lower corrosion rate indicates less weight loss in the high-nickel alloy, thus indicating better corrosion resistance.

[0061] The results in Table 3 show that, under different corrosion test conditions, the corrosion rates of Experimental Examples 1 to 4 were all lower than those of Comparative Examples 1 to 2. In particular, under high temperature conditions (650°C or 850°C), the corrosion rates of Experimental Examples 1 to 4 were significantly lower than those of Comparative Examples 1 to 2.

[0062] In detail, because titanium and niobium, which have solid solution strengthening effects, were added to Examples 1 to 4, and secondary phases of niobium titanium carbide and niobium carbonitride titanium carbonitride were generated, the high-nickel alloy could be strengthened, and the carbon element was stabilized to suppress graphitization. Therefore, Examples 1 to 4 exhibited better corrosion resistance. More specifically, because niobium titanium carbide and niobium carbonitride titanium carbonitride combine the strength of TiC and TiCN with the stability of NbC and NbCN, and have more suitable secondary phase size and dispersion strengthening effect, they are more effective in suppressing grain coarsening at high temperatures. Therefore, compared with TiC, TiCN, NbC, and NbCN, the niobium titanium carbide and niobium carbonitride titanium carbonitride in this case are high-temperature microstructure-stabilizing strengthening phases.

[0063] Figure 2A is a scanning electron microscope image 210 of the high-nickel alloy of Experimental Example 1 according to the present disclosure after corrosion testing at 850°C. As can be seen from Figure 2A, precipitates 212 are present within the grains of the high-nickel alloy, and precipitates 214 are present at the grain boundaries. Precipitates 212 and 214 comprise titanium niobium carbide, titanium niobium carbonitride, or a combination thereof. Precipitates 212 have a blocky morphology, as shown in Figure 2A. Precipitates 214 are smaller than precipitates 212 and are more numerous. The size of precipitates 212 is approximately 0.5 µm to 5 µm. The size of precipitates 212 is approximately 20 nm to 300 nm, which is at the submicron or nanometer scale.

[0064] Figure 2B shows the energy-scattered X-ray spectrum 220 of the precipitate 212 after a corrosion test at 850°C on the high-nickel alloy of Experimental Example 1 according to this disclosure. As can be seen from Figure 2B, precipitate 212 contains titanium and niobium, and also contains nitrogen. This indicates that nitrogen is dissolved in precipitate 212.

[0065] Figure 3A is a scanning electron microscope image 310 of the high-nickel alloy of Comparative Example 1 after a corrosion test at 850°C according to the present disclosure. As can be seen from the scanning electron microscope image 310, the grains of Comparative Example 1 have become coarse and corrosion cracking has occurred at the grain boundaries, which is presumably related to graphitization of the grain boundaries at high temperatures.

[0066] Figure 3B is a scanning electron microscope (SEM) image 320 of the high-nickel alloy of Experimental Example 1 according to this disclosure after a corrosion test at 850°C. As can be seen from the SEM image 320, compared to Comparative Example 1, the grain size of Experimental Example 1 is smaller, and there is no obvious corrosion at the grain boundaries. Because titanium and niobium were added to Experimental Example 1, grain growth was effectively suppressed, and the corrosion of the high-nickel alloy was not obvious.

[0067] Please refer to Tables 1 to 3. Comparing Experiments 1 and 4, it can be seen that although Experiment 4 added more titanium and niobium, the improvement in mechanical properties and corrosion resistance was limited. The elongation results show that, compared to Experiment 1, the secondary phase in Experiment 4 was larger, hence the lower elongation.

[0068] Based on the above, compared with TiC, TiCN, NbC and NbCN, the niobium titanium carbide and niobium carbonitride titanium of this case exhibit better stability and corrosion resistance in alkaline environments. Due to their low lattice mismatch and interface energy, they can provide a stable corrosion barrier and are not prone to galvanic corrosion with the substrate.

[0069] The high-nickel alloy disclosed herein contains specific amounts of titanium and niobium. In the high-temperature (e.g., 600°C to 900°C) caustic alkali industrial environment, the high-nickel alloy disclosed herein can inhibit graphitization and maintain good mechanical strength. Therefore, it can prevent softening or corrosion and embrittlement at petrified grain boundaries in the high-nickel alloy at high temperatures, further preventing its cracking, and exhibiting excellent corrosion resistance. The high-nickel alloy disclosed herein, with its high-temperature strength and corrosion resistance, can be used, for example, as caustic alkali production equipment, chlor-alkali industry equipment parts, gas preparation and diffusion elements, raw material reactor linings or furnace tubes, chemical heating furnaces or conduits, battery or electronic grade material smelting equipment, etc., but is not limited to these applications.

[0070] It is understood that although this disclosure uses specific compositions, manufacturing methods and evaluation methods as examples to illustrate the high-nickel alloys and their manufacturing methods, it is clear to anyone with ordinary knowledge in the technical field that this disclosure is not limited thereto. Other compositions, manufacturing methods or evaluation methods may also be used without departing from the spirit and scope of this disclosure.

[0071] Although the present disclosure has been described above with reference to embodiments, it is not intended to limit the present disclosure. Anyone with ordinary knowledge in the art to which the present disclosure pertains may make various modifications and refinements without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the appended claims.

[0072] 100: Manufacturing Method 110, 120, 130: Steps 210, 310, 320: Scanning electron microscope images 212, 214: Precipitates 220: Energy Scattering X-ray Spectrum

[0073] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A high-nickel alloy, comprising, by weight 100%,: 95% to 99.3% nickel; 0.15% to 3% titanium; 0.15% to 3% niobium; not more than 0.35% silicon; not more than 0.35% manganese; not more than 0.35% iron; not more than 0.15% carbon; and unavoidable impurities, wherein the impurities comprise cobalt, chromium, copper, aluminum, phosphorus, sulfur, or a combination of the foregoing elements.

2. The high-nickel alloy as claimed in claim 1, wherein the total content of the titanium and the niobium is from 0.3% to 5% by weight.

3. The high-nickel alloy as claimed in claim 1, wherein the ratio of titanium to niobium content is 0.1 to 10.

4. The high-nickel alloy as claimed in claim 3, wherein the ratio of titanium to niobium is 0.4 to 2.

5.

5. The high-nickel alloy as claimed in claim 1, wherein a precipitate of the high-nickel alloy comprises titanium niobium carbide, titanium carbonitride, or a combination thereof, and the size of the precipitate within a grain of the high-nickel alloy is 0.5 µm to 5 µm.

6. The high-nickel alloy as claimed in claim 1, wherein a precipitate of the high-nickel alloy comprises titanium niobium carbide, titanium niobium carbonitride, or a combination thereof, and the size of the precipitate on a grain boundary of the high-nickel alloy is 20 nm to 300 nm.

7. The high-nickel alloy as claimed in claim 1, wherein at 25°C, the high-nickel alloy has a tensile strength of at least 485 MPa, a yield strength of at least 312 MPa, and an elongation of at least 22%.

8. The high-nickel alloy as claimed in claim 1, wherein at 650°C, the high-nickel alloy has a tensile strength of at least 292 MPa, a yield strength of at least 61 MPa, and an elongation of at least 82%.

9. The high-nickel alloy as claimed in claim 1, wherein at 850°C, the high-nickel alloy has a tensile strength of at least 101 MPa, a yield strength of at least 52 MPa, and an elongation of at least 95%.

10. A method for manufacturing a high-nickel alloy, comprising: providing an alloy billet comprising, by weight percentage (100%): 95% to 99.3% nickel; 0.15% to 3% titanium; 0.15% to 3% niobium; not more than 0.35% silicon; not more than 0.35% manganese; not more than 0.35% iron; not more than 0.15% carbon; and unavoidable impurities, wherein the impurities comprise cobalt, chromium, copper, aluminum, phosphorus, sulfur, or a combination of the above elements; and smelting the alloy billet to obtain the high-nickel alloy.

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