Smelting method of ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy

Abstract

The present invention relates to the technical field of alloy smelting, and specifically discloses a smelting method for ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy. The present invention performs electric furnace smelting on raw materials to obtain a first molten steel; the first molten steel is injected into an AOD furnace for a first refining, and nitrogen is blown throughout the process to control [Cr]+[Mn]-[Si]≥33% to obtain a second molten steel; under a nitrogen atmosphere, the second molten steel is injected into an LF furnace for a second refining, and a deoxidizer is continuously added throughout the process for deoxidation; calcium wire and metallic cerium are added before tapping to obtain a third molten steel; the third molten steel is cast to obtain an electrode blank; under a protective atmosphere, the electrode blank is subjected to electroslag remelting to obtain an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy. The present invention adopts the process route of "electric furnace + AOD furnace + LF furnace + electroslag", which solves the problem of unqualified carbon content and nitrogen content when vacuum induction smelting is adopted, and has high market competitiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy smelting, and in particular to a method for smelting an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy. Background Art

[0002] Ultra-high nitrogen, ultra-low carbon Fe-Cr-Ni-based superalloys offer excellent corrosion resistance and high strength, making them suitable for harsh environments such as chemical engineering and marine environments. They can even be used at high temperatures in highly oxidizing, high-concentration inorganic acid media. 015Cr33Ni32MoCuN alloy is an ultra-high nitrogen, ultra-low carbon Fe-Cr-Ni-based superalloy. Industry standards require C ≤ 0.015%, N 0.35% to 0.60%, and Fe, Cr, and Ni content to be above 30%. The specific composition is shown in Table 1.

[0003] Table 1015Cr33Ni32MoCuN alloy chemical composition and mass percentage (%)

[0004]

[0005] During the smelting process of superalloys, segregation is prone to occur due to the high concentration of alloying elements. To reduce this segregation, superalloys are generally smelted using a "vacuum induction furnace + electroslag" or "vacuum induction furnace + consumable" process. However, due to the specific compositional requirements of ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni-based superalloys, vacuum induction melting has the following disadvantages: The high nitrogen content of these steels makes it very easy to extract the nitrogen when smelted in a vacuum, resulting in a nitrogen content (by mass) below 0.35%. Furthermore, due to the low carbon content of these steels, vacuum induction melting is incapable of decarburization. Furthermore, to maintain the nitrogen content, a large amount of chromium nitride must be added in the later stages of smelting. Chromium nitride contains a certain amount of carbon, which can easily cause the carbon content to exceed the upper limit required by the standard during smelting. Furthermore, smelting costs are high. Therefore, there is an urgent need to find a smelting method suitable for ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni-based superalloys that meets the corresponding chemical composition and quality requirements. Summary of the Invention

[0006] In response to the above problems, the present invention provides a smelting method for an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high-temperature alloy. The present invention adopts the process of "electric furnace + AOD furnace + LF furnace + electroslag". By limiting the chemical composition of the raw materials and the conditions of each smelting stage, the nitrogen content and carbon content in the alloy are better controlled, and an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high-temperature alloy whose chemical composition meets industry standards is obtained, thereby improving the comprehensive performance of the high-temperature alloy.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A smelting method for an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy comprises the following steps:

[0009] S1, melting the raw materials in an electric furnace to obtain the first molten steel;

[0010] The raw materials are prepared according to the following chemical compositions by mass percentage: Cr 31.75%-34.00%, Ni 30.70%-32.00%, Mo 0.60%-1.00%, Cu 0.60%-0.90%;

[0011] S2, injecting the first molten steel into an AOD furnace for first refining, blowing oxygen until C≤0.006wt% and Si≤0.01wt%, starting nitrogen blowing throughout the process, adding aluminum and ferrosilicon for reduction reaction, and controlling [Cr]+[Mn]-[Si]≥33% to obtain a second molten steel;

[0012] Wherein, [Cr] represents the mass content of Cr element, [Mn] represents the mass content of Mn element, and [Si] represents the mass content of Si element;

[0013] S3, under a nitrogen atmosphere, injecting the second molten steel into the LF furnace for second refining, continuously adding deoxidizer for deoxidation throughout the process; adding calcium wire and metallic cerium before tapping to obtain a third molten steel;

[0014] The deoxidizer is selected from at least one of aluminum wire and aluminum powder;

[0015] S4, casting the third molten steel to obtain an electrode blank;

[0016] S5, in a protective atmosphere, electroslag remelting the electrode blank to obtain an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy.

[0017] Compared to existing technologies, the smelting method for an ultra-high-nitrogen, ultra-low-carbon Fe-Cr-Ni-based superalloy provided by the present invention utilizes an "electric furnace + AOD furnace + LF furnace + electroslag" process, resolving the issue of substandard carbon and nitrogen contents during vacuum induction smelting. This method offers high market competitiveness and promotional value. By limiting the contents of Cr, Ni, Mo, and Cu in the raw material batches, the present invention effectively prevents segregation of these elements during subsequent smelting processes or composition adjustments, thereby preventing increased smelting time and carbon content exceeding the upper limit. Furthermore, by limiting the combined content of Mn, Cr, and Si (i.e., [Cr] + [Mn] - [Si]) during the first refining process, the solubility of nitrogen in molten steel is increased, thereby ensuring that the nitrogen content in the alloy meets standard requirements.

[0018] The present invention creatively performs nitrogen blowing throughout the first refining process, ensuring that the nitrogen content in the alloy is within the specified range of industry standards, which not only increases the nitrogen content in the molten steel, but also ensures that the nitrogen content does not exceed 0.60%. The present invention uses nitrogen as a protective gas in the second refining process, which can further prevent the reduction of nitrogen elements; uses aluminum wire or aluminum powder as a deoxidizer, avoids the use of silicon calcium powder, and can further prevent carbon increase; before the second refining of steel, the addition of calcium wire and metallic cerium can effectively prevent the molten steel from increasing in oxygen during the subsequent casting process, thereby ensuring that the oxygen content is qualified. Subsequent electroslag remelting is combined to produce an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high-temperature alloy whose chemical components meet industry standards, and improves the thermal processing performance and comprehensive performance of the high-temperature alloy, effectively improving the smelting success rate of the high-temperature alloy.

[0019] Preferably, the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy is a 015Cr33Ni32MoCuN alloy, comprising the following chemical components in percentage by mass: C≤0.012%, Si≤0.50%, Mn≤2.00%, P≤0.020%, S≤0.010%, Cr 31.00%~35.00%, Ni 30.00%~33.00%, Mo 0.50%~2.00%, Cu 0.30%~1.20%, N 0.40%~0.47%, and the balance is Fe and unavoidable impurities.

[0020] Preferably, in S1, the raw materials are formulated according to the following chemical compositions in percentage by mass: Mn 0.80%-1.60%, P≤0.018%, Cr 31.75%-34.00%, Ni 30.70%-32.00%, Mo 0.60%-1.00%, and Cu 0.60%-0.90%.

[0021] When preparing the ingredients, C and Si elements can be appropriately increased to prepare for the subsequent oxygen blowing to control the temperature of the molten steel; other chemical components can be conventionally configured according to the above chemical components, and the present invention does not require them.

[0022] Further preferably, in S1, the raw materials are formulated according to the following chemical compositions in percentage by mass: Cr 32.5%, Ni 30.8%, Mo 0.80%, and Cu 0.75%.

[0023] The preferred contents of Cr, Ni, Mo and Cu in the ingredients of the present invention can further prevent the segregation of the elements and the resulting substandard products during the subsequent smelting process or composition adjustment.

[0024] Preferably, in S2, after the aluminum and ferrosilicon are added, the mass content of Si in the molten steel is 0.25% to 0.45%, and the mass content of Al is 0.015% to 0.045%.

[0025] During the first refining of the first molten steel in the AOD furnace, oxygen is first blown to oxidize the C and Si elements (the Cr content will also decrease due to oxidation) to ensure the temperature of the first refining. When C ≤ 0.006wt% and Si ≤ 0.01wt% in the molten steel, aluminum and ferrosilicon are added for a reduction reaction to return the Cr content to the set range, and nitrogen blowing is started throughout the process. At the same time, the [Cr] + [Mn] - [Si] content is controlled, which can significantly increase the solubility of nitrogen in the molten steel, thereby ensuring that the nitrogen content in the alloy meets the standard requirements.

[0026] Preferably, in S3, the total amount of the deoxidizer added is 0.5 kg / t to 1.5 kg / t.

[0027] For example, in S3, calcium wire and metallic cerium are added 3 to 5 minutes before tapping.

[0028] Preferably, in S3, the amount of calcium wire added is 2.8m / t to 3.2m / t, and the amount of metallic cerium added is 0.2kg / t to 0.3kg / t.

[0029] The present invention can further effectively prevent oxygenation in subsequent processes by limiting the added amounts of the deoxidizer, calcium wire and metal cerium.

[0030] Preferably, in S4, the casting temperature is 1470°C to 1490°C.

[0031] Preferably, in S4, the diameter of the electrode blank is 340 mm to 430 mm.

[0032] Preferably, in S5, the protective atmosphere is a nitrogen atmosphere.

[0033] Preferably, in S5, the slag system used in the electroslag remelting is CaF2, Al2O3, CaO and MgO in a mass ratio of (68~72):(19~21):(4.5~5.5):(4.5~5.5).

[0034] Further preferably, in S5, the carbon content of the slag system is ≤0.03%.

[0035] Preferably, in S5, the melting rate of the electrode blank is 4.5 kg / min to 7 kg / min.

[0036] Preferably, in S5, the diameter of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy is 480 mm to 590 mm.

[0037] The present invention can further ensure that the chemical composition and gas content of the final electroslag ingot are within a reasonable range through a specific electroslag remelting slag system and a melting rate of the electrode blank, and ensure that the corresponding inclusions can be ≤1.0 level, thereby ensuring that the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy has excellent hot working performance and comprehensive performance. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] Unless otherwise specified, the percentages in the present invention are all by mass.

[0040] Example 1

[0041] This embodiment provides a smelting method of 015Cr33Ni32MoCuN alloy, comprising the following steps:

[0042] S1, smelting the raw materials in an electric furnace to obtain the first molten steel.

[0043] The raw materials are formulated according to the following chemical composition in percentage by mass: Mn 1.35%, P≤0.018%, Cr32.22%, Ni 31.00%, Mo 0.80%, and Cu 0.70%.

[0044] S2, inject the first molten steel into the AOD furnace for the first refining, blow oxygen until C ≤ 0.006wt% and Si ≤ 0.01wt% in the molten steel, start nitrogen blowing throughout the process, and add aluminum and ferrosilicon for reduction reaction. Adjust elements such as Cr, Ni, Mo and Cu to the internal control range. During this process, Si 0.30%, Mn 1.35%, P ≤ 0.018%, Cr 32.22%, Ni 31.00%, Mo 0.80%, Cu 0.70% and Al 0.03% are controlled, [Cr] + [Mn] - [Si] = 33.27%, and the second molten steel is obtained.

[0045] In S3, under a nitrogen atmosphere, the second molten steel is injected into the LF furnace for the second refining. A total of 1 kg / t of aluminum wire is continuously added for deoxidation throughout the process. 3 m / t of calcium wire and 0.25 kg / t of metallic cerium are added 3 to 5 minutes before tapping. Sampling is performed for analysis. After the chemical composition is qualified, the steel is tapped to obtain the third molten steel.

[0046] S4, casting the third molten steel at 1480°C to obtain an electrode blank of Φ380mm.

[0047] S5. Under a protective atmosphere, the electrode blank is subjected to electroslag remelting. The slag system used for electroslag remelting is CaF2, Al2O3, CaO and MgO with a mass ratio of 70:20:5:5. The carbon content of the slag system is ≤0.03%. The melting rate of the electrode blank is 5.6 kg / min, and an electroslag ingot of Φ530 mm is obtained, namely 015Cr33Ni32MoCuN alloy.

[0048] 015Cr33Ni32MoCuN alloy consists of the following chemical components in mass percentage: C 0.010%, Si 0.30%, Mn 1.35%, P ≤ 0.020%, S ≤ 0.010%, Cr 32.22%, Ni 30.98%, Mo 0.81%, Cu 0.69%, N 0.43%, Al 0.02%, O ≤ 20ppm, H ≤ 8ppm, and the balance is Fe and unavoidable impurities.

[0049] Example 2

[0050] This embodiment provides a smelting method of 015Cr33Ni32MoCuN alloy, comprising the following steps:

[0051] S1, smelting the raw materials in an electric furnace to obtain the first molten steel.

[0052] The raw materials are formulated according to the following chemical composition in percentage by mass: Mn 1.60%, P≤0.018%, Cr31.75%, Ni 30.70%, Mo 1.00%, Cu 0.60%, and the balance is Fe and unavoidable impurities.

[0053] S2, injecting the first molten steel into the AOD furnace for the first refining, blowing oxygen until C ≤ 0.006wt% and Si ≤ 0.01wt% in the molten steel, starting nitrogen blowing throughout the process, and adding aluminum and ferrosilicon for reduction reaction, adjusting elements such as Cr, Ni, Mo and Cu to the internal control range. During this process, Si 0.25%, Mn 1.60%, P ≤ 0.018%, Cr 31.75%, Ni 30.70%, Mo 1.00%, Cu 0.60% and Al 0.045% are controlled, [Cr] + [Mn] - [Si] = 33.1%, and obtaining the second molten steel.

[0054] In S3, under nitrogen atmosphere, the second molten steel is injected into the LF furnace for the second refining. A total of 0.5 kg / t of aluminum powder is continuously added for deoxidation throughout the process. 2.8 m / t of calcium wire and 0.3 kg / t of metallic cerium are added 3-5 minutes before tapping. Sampling is performed for analysis. After the chemical composition is qualified, the steel is tapped to obtain the third molten steel.

[0055] S4, casting the third molten steel at 1470°C to obtain an electrode blank of Φ340mm.

[0056] S5. Under a protective atmosphere, the electrode blank is electroslag remelted. The slag system used for electroslag remelting is CaF2, Al2O3, CaO and MgO with a mass ratio of 68:21:5.5:5.5. The carbon content of the slag system is ≤0.03%. The melting rate of the electrode blank is 4.5 kg / min, and an electroslag ingot of Φ480 mm is obtained, which is 015Cr33Ni32MoCuN alloy.

[0057] 015Cr33Ni32MoCuN alloy consists of the following chemical components in mass percentage: C 0.012%, Si 0.25%, Mn 1.74%, P ≤ 0.020%, S ≤ 0.010%, Cr 31.07%, Ni 30.14%, Mo 1.82%, Cu 0.37%, N 0.40%, Al 0.045%, O ≤ 23ppm, H ≤ 5ppm, and the balance is Fe and unavoidable impurities.

[0058] Example 3

[0059] This embodiment provides a smelting method of 015Cr33Ni32MoCuN alloy, comprising the following steps:

[0060] S1, smelting the raw materials in an electric furnace to obtain the first molten steel.

[0061] The raw materials are formulated according to the following chemical composition in percentage by mass: Mn 0.80%, P≤0.018%, Cr34.00%, Ni 32.00%, Mo 0.60%, Cu 0.90%, and the balance is Fe and unavoidable impurities.

[0062] S2, injecting the first molten steel into the AOD furnace for the first refining, blowing oxygen until C ≤ 0.006wt% and Si ≤ 0.01wt% in the molten steel, starting nitrogen blowing throughout the process, and adding aluminum and ferrosilicon for reduction reaction, adjusting elements such as Cr, Ni, Mo and Cu to the internal control range. During this process, Si 0.45%, Mn 0.80%, P ≤ 0.018%, Cr 34.00%, Ni 32.00%, Mo0.60%, Cu 0.90% and Al 0.015% are controlled, [Cr] + [Mn] - [Si] = 34.35%, and the second molten steel is obtained.

[0063] In S3, under a nitrogen atmosphere, the second molten steel is injected into the LF furnace for the second refining. During the whole process, 1kg / t of aluminum wire and 0.5kg / t of aluminum powder are continuously added for deoxidation. 3min to 5min before tapping, 3.2m / t of calcium wire and 0.2kg / t of metallic cerium are added. Sampling is performed for analysis. After the chemical composition is qualified, the steel is tapped to obtain the third molten steel.

[0064] S4, casting the third molten steel at 1490°C to obtain an electrode blank of Φ430mm.

[0065] S5. Under a protective atmosphere, the electrode blank is electroslag remelted. The slag system used for electroslag remelting is CaF2, Al2O3, CaO and MgO with a mass ratio of 72:19:4.5:4.5. The carbon content of the slag system is ≤0.03%. The melting rate of the electrode blank is 7kg / min, and an electroslag ingot of Φ590mm is obtained, which is 015Cr33Ni32MoCuN alloy.

[0066] 015Cr33Ni32MoCuN alloy consists of the following chemical components in mass percentage: C 0.010%, Si 0.45%, Mn 0.80%, P ≤ 0.020%, S ≤ 0.010%, Cr 34.82%, Ni 32.57%, Mo 0.53%, Cu 1.15%, N 0.46%, Al 0.02%, O ≤ 20ppm, H ≤ 6ppm, and the balance is Fe and unavoidable impurities.

[0067] Example 4

[0068] This embodiment provides a smelting method of 015Cr33Ni32MoCuN alloy, comprising the following steps:

[0069] S1, smelting the raw materials in an electric furnace to obtain the first molten steel.

[0070] The raw materials are formulated according to the following chemical composition in percentage by mass: Mn 1.13%, P≤0.018%, Cr32.45%, Ni 31.15%, Mo 0.88%, Cu 0.69%, and the balance is Fe and unavoidable impurities.

[0071] S2, the first molten steel is injected into the AOD furnace for the first refining, oxygen is blown until C ≤ 0.006wt% and Si ≤ 0.01wt% in the molten steel, nitrogen blowing is started throughout the process, and aluminum and ferrosilicon are added for reduction reaction. Elements such as Cr, Ni, Mo and Cu are adjusted to the internal control range. During this process, Si is controlled at 0.40%, Mn at 1.13%, P ≤ 0.018%, Cr 32.45%, Ni 31.15%, Mo 0.88%, Cu 0.69% and Al 0.02%, [Cr] + [Mn] - [Si] = 33.27%, and the second molten steel is obtained.

[0072] In S3, under a nitrogen atmosphere, the second molten steel is injected into the LF furnace for the second refining. A total of 1 kg / t of aluminum wire is continuously added for deoxidation throughout the process. 3 m / t of calcium wire and 0.25 kg / t of metallic cerium are added 3 to 5 minutes before tapping. Sampling is performed for analysis. After the chemical composition is qualified, the steel is tapped to obtain the third molten steel.

[0073] S4, casting the third molten steel at 1480°C to obtain an electrode blank of Φ390mm.

[0074] The electrode blank is composed of the following chemical components in percentage by mass: C 0.012%, Si 0.40%, Mn 1.13%, P≤0.020%, S≤0.010%, Cr 32.45%, Ni 31.12%, Mo 0.85%, Cu 0.67%, N 0.41%, Al 0.02%, O≤22ppm, H≤7ppm, and the balance is Fe and unavoidable impurities.

[0075] S5. Under a protective atmosphere, the electrode blank is electroslag remelted. The slag system used for electroslag remelting is CaF2, Al2O3 and CaO with a mass ratio of 70:15:15. The melting rate of the electrode blank is 5.8 kg / min, and an electroslag ingot of Φ540 mm is obtained, which is 015Cr33Ni32MoCuN alloy.

[0076] 015Cr33Ni32MoCuN alloy consists of the following chemical components in mass percentage: C 0.016%, Si 0.40%, Mn 1.13%, P ≤ 0.020%, S ≤ 0.010%, Cr 32.45%, Ni 31.12%, Mo 0.85%, Cu 0.67%, N 0.41%, Al 0.02%, O ≤ 22ppm, H ≤ 7ppm, and the balance is Fe and unavoidable impurities.

[0077] Comparative Example 1

[0078] This comparative example provides a smelting method of 015Cr33Ni32MoCuN alloy, which adopts a vacuum induction smelting method and includes the following steps:

[0079] The vacuum induction furnace (1t) uses pure metal ingredients. The mid-term inspection of smelting shows C 0.005% and N 0.004%. After the other chemical compositions are appropriate, argon is filled at 10,000Pa in the later stage of smelting, and nitrogen is increased by adding chromium nitride. Chromium nitride contains about 3% N. 150kg of chromium nitride is added to finally obtain a Φ380mm electrode blank.

[0080] The obtained electrode blank was tested for chemical composition and was found to be composed of the following chemical components by mass percentage: C 0.018%, Si 0.40%, Mn 1.70%, P ≤ 0.020%, S ≤ 0.010%, Cr 33.07%, Ni 30.65%, Mo 0.88%, Cu 0.73%, N 0.24%, Al 0.02%, O 15 ppm, H 0.5 ppm, and the balance being Fe and unavoidable impurities.

[0081] Because the C element exceeded the upper limit and the N element was lower than the lower limit, the chemical composition was unqualified and production was stopped.

[0082] Comparative Example 2

[0083] This comparative example provides a smelting method for a 015Cr33Ni32MoCuN alloy, similar to Example 1, except that in S2, Cr is 31.45%, Mn is 1.04%, and Si is 0.43%, with [Cr] + [Mn] - [Si] = 32.06. The remaining conditions are the same as in Example 1 and are not further described.

[0084] The chemical composition of the third molten steel was tested and it was found that the nitrogen content was only 0.34%. The chemical composition was unqualified and production was stopped.

[0085] Comparative Example 3

[0086] This comparative example provides a smelting method for 015Cr33Ni32MoCuN alloy, similar to Example 1, except that in S3, the aluminum wire is replaced with calcium silicate powder of equal mass. The remaining conditions are the same as in Example 1 and are not further described.

[0087] The chemical composition of the third molten steel was tested, and it was found that the content of C element gradually increased to 0.017% before steelmaking. The chemical composition was unqualified, and production was stopped.

[0088] Comparative Example 4

[0089] This comparative example provides a 015Cr33Ni32MoCuN alloy smelting method similar to Example 1, except that in S3, only calcium wire is added, and metallic cerium is omitted. The remaining conditions are the same as in Example 1 and are not further described.

[0090] 015Cr33Ni32MoCuN alloy consists of the following chemical components in mass percentage: C 0.010%, Si 0.30%, Mn 1.35%, P≤0.020%, S≤0.010%, Cr 32.22%, Ni 30.98%, Mo 0.81%, Cu 0.69%, N 0.43%, Al 0.02%, O≤32ppm, H≤8ppm, and the balance is Fe and unavoidable impurities.

[0091] During the later forging process, the 015Cr33Ni32MoCuN alloy has many cracks on its surface, which leads to a low yield and increased cost.

[0092] Comparative Example 5

[0093] This comparative example provides a 015Cr33Ni32MoCuN alloy smelting method, which is similar to Example 1, except that nitrogen is blown only in the first half of S2. The remaining conditions are the same as those in Example 1 and are not repeated here.

[0094] The chemical composition of the third molten steel was tested. The nitrogen content of the AOD furnace sample was 0.4%, and the nitrogen content of the LF furnace sample gradually decreased to 0.32%. The chemical composition was unqualified and production was stopped.

[0095] Performance Testing

[0096] The 015Cr33Ni32MoCuN alloys prepared in Examples 1-4 and Comparative Example 4 were subjected to inclusion level testing and mechanical property testing (testing standards refer to GB / T 228.1-2021). The test results are shown in Tables 2-3. As can be seen from Tables 2-3, compared to Examples 1-3, the electroslag remelting slag system of Example 4 contains more CaO, which contains a small amount of carbon. As a result, the carbon content at the bottom of the electroslag ingot is 0.016%, which does not meet the standard requirements. This leads to a low yield and increased costs.

[0097] Table 2 Inclusion levels of 015Cr33Ni32MoCuN alloys of Examples 1 to 4 and Comparative Example 4

[0098]

[0099] Table 3 Mechanical properties test results of 015Cr33Ni32MoCuN alloy of Examples 1 to 4 and Comparative Example 4

[0100]

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for smelting ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy, characterized in that: The following steps are involved: S1, melting the raw materials in an electric furnace to obtain the first molten steel; The raw materials are prepared according to the following chemical compositions by mass percentage: Cr 31.75%-34.00%, Ni 30.70%-32.00%, Mo 0.60%-1.00%, Cu 0.60%-0.90%; S2, injecting the first molten steel into an AOD furnace for first refining, blowing oxygen until C≤0.006wt% and Si≤0.01wt%, starting nitrogen blowing throughout the process, adding aluminum and ferrosilicon for reduction reaction, and controlling [Cr]+[Mn]-[Si]≥33.27% to obtain a second molten steel; Wherein, [Cr] represents the mass content of Cr element, [Mn] represents the mass content of Mn element, and [Si] represents the mass content of Si element; S3, under a nitrogen atmosphere, injecting the second molten steel into the LF furnace for second refining, continuously adding deoxidizer for deoxidation throughout the process; adding calcium wire and metallic cerium before tapping to obtain a third molten steel; The deoxidizer is selected from at least one of aluminum wire and aluminum powder; S4, casting the third molten steel to obtain an electrode blank; S5, electroslag remelting the electrode blank under a nitrogen atmosphere to obtain an ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy; the slag system used in the electroslag remelting is CaF2, Al2O3, CaO and MgO in a mass ratio of (68-72):(19-21):(4.5-5.5):(4.5-5.5); The ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy is a 015Cr33Ni32MoCuN alloy, comprising the following chemical components in percentage by mass: C≤0.012%, Si≤0.50%, Mn≤2.00%, P≤0.020%, S≤0.010%, Cr 31.00%~35.00%, Ni 30.00%~33.00%, Mo 0.50%~2.00%, Cu 0.30%~1.20%, N 0.41%~0.47%, with the remainder being Fe and unavoidable impurities.

2. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S1, the raw materials are prepared according to the following chemical compositions in percentage by mass: Mn 0.80%-1.60%, P≤0.018%, Cr31.75%-34.00%, Ni 30.70%-32.00%, Mo 0.60%-1.00%, and Cu 0.60%-0.90%.

3. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S2, after the aluminum and ferrosilicon are added, the mass content of Si in the molten steel is 0.25% to 0.45%, and the mass content of Al is 0.015% to 0.045%.

4. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S3, the total amount of the deoxidizer added is 0.5 kg / t to 1.5 kg / t.

5. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S3, the amount of calcium wire added is 2.8m / t~3.2m / t, and the amount of metallic cerium added is 0.2kg / t~0.3kg / t.

6. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S4, the casting temperature is 1470°C to 1490°C.

7. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S5, the carbon content of the slag system is ≤0.03%.

8. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1, characterized in that: In S4, the diameter of the electrode blank is 340 mm to 430 mm.

9. The smelting method of the ultra-high nitrogen and ultra-low carbon Fe-Cr-Ni based high temperature alloy according to claim 1 or 8, characterized in that: In S5, the melting rate of the electrode blank is 4.5 kg / min to 7 kg / min.

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