Vacuum consumable melting method of high-nitrogen martensitic heat-resistant steel

Abstract

The invention relates to the technical field of metallurgy, and particularly discloses a vacuum consumable smelting method of high-nitrogen martensitic heat-resistant steel, which comprises the following steps: S110, preparing a consumable electrode, and loading the consumable electrode into an electric vacuum consumable furnace; s120, the electro-vacuum consumable electrode furnace is subjected to vacuum pumping treatment, and then protective gas is filled into the electro-vacuum consumable electrode furnace; s130, a molten pool is formed after electrifying and arcing, and first-stage smelting is started; s140, according to the weight percentage, when 20%-30% of the consumable electrode is left, second-stage smelting is started, and the second-stage smelting is filling smelting; and S150, after smelting is completed, cooling and ingot stripping are conducted, and the consumable ingot is obtained. According to the method, the nitrogen loss in the smelting process of the high-nitrogen martensitic heat-resistant steel is reduced by controlling the protective atmosphere of vacuum consumable smelting, and high-quality stable production of the high-nitrogen martensitic heat-resistant steel can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a vacuum consumable smelting method for high-nitrogen martensitic heat-resistant steel. Background Art

[0002] High nitrogen martensitic heat-resistant steel is an important material for manufacturing parts working at high temperatures in industries such as boilers, steam turbines, power machinery, industrial furnaces, aviation, and petrochemicals. It needs to have high strength and good chemical stability at high temperatures, sufficient toughness, good machinability and weldability, and certain structural stability. In order to meet the long service life of the material, extremely high requirements are placed on the purity of the material and the uniformity of the solidified structure.

[0003] At present, the methods for producing high-end high-nitrogen martensitic heat-resistant steel all require secondary refining using a vacuum consumable smelting process. The vacuum consumable smelting (VAR) process can effectively remove impurities (O, H, S, etc.) and accurately control the content of gases (such as N) by melting the consumable electrode in a vacuum environment and using arc heat to melt layer by layer. For this high-end high-nitrogen martensitic heat-resistant steel, nitrogen plays an important role in improving its high-temperature performance. However, the segregation and loss of nitrogen in the conventional vacuum consumable smelting process are very obvious, resulting in obvious pores in the consumable ingot, which seriously reduces the performance of the steel. At the same time, due to the large amount of alloy in the steel, segregation and loose shrinkage cavities are prone to occur during the smelting process.

[0004] Therefore, how to improve the quality of high nitrogen martensitic heat-resistant steel ingots has become a technical problem that needs to be solved urgently in the metallurgical field. Summary of the invention

[0005] In view of the deficiencies in the prior art, the main purpose of the present invention is to provide a vacuum consumable melting method for high-nitrogen martensitic heat-resistant steel, so as to solve the problems of high purity, composition uniformity, porosity and loose shrinkage cavities of the material under industrial preparation.

[0006] In order to solve at least one of the above technical problems, the present invention adopts the following technical solution: According to the present invention, a vacuum consumable melting method for high nitrogen martensitic heat-resistant steel is provided, comprising the following steps: S110, preparing a consumable electrode and loading it into an electric vacuum consumable furnace; S120, evacuating the electric vacuum consumable furnace and then filling it with a protective gas; S130, forming a molten pool after power-on and arcing, and starting the first stage of melting; S140, when the consumable electrode remains at 20% to 30% by weight, starting the second stage of melting, wherein the second stage of melting is filling melting; S150, cooling and stripping the ingot after the melting is completed to obtain a consumable ingot.

[0007] According to an embodiment of the present invention, in step S110, the consumable electrode is obtained by electric furnace melting + argon oxygen decarburization + ladle refining or vacuum induction melting method. Among them, the consumable electrode is composed of chemical components with the following weight percentages: 0.08% - 0.15% of C, 0.5% - 1.4% of Mn, 2% - 4% of Ni, 9% - 12% of Cr, 1.5% - 3% of Mo, 0.2% - 1% of V, 0.06% - 0.1% of N, 0.11% - 0.14% of Si, 0.0032% - 0.0045% of P, 0.0019% - 0.002% of S, and the balance is Fe and inevitable impurities.

[0008] According to an embodiment of the present invention, in step S110, the consumable electrode is subjected to cap cutting and surface skimming before being loaded into the electro-vacuum consumable furnace.

[0009] According to an embodiment of the present invention, in step S120, the electro-vacuum consumable furnace is first evacuated to below 1 Pa, and then dry nitrogen is filled.

[0010] According to an embodiment of the present invention, in step S120, the pressure of the filled dry nitrogen is 5 - 20 Pa.

[0011] According to an embodiment of the present invention, in step S130, a control system of melting rate + number of droplets is adopted during the first-stage melting.

[0012] According to an embodiment of the present invention, in step S130, the melting rate is controlled at 4.0 - 6.5 kg / min, and the number of droplets is 1 - 15 (1 / s).

[0013] According to an embodiment of the present invention, in step S140, a control system of melting rate + voltage is adopted during the second-stage melting.

[0014] According to an embodiment of the present invention, in step S140, the second-stage melting is filled in multiple stages. The current is controlled at 8.0 - 4.0 A, the voltage is controlled at 24.0 - 21.0 V, the melting rate is controlled at 4.0 - 1.0 kg / min, the voltage and current are gradually reduced, the voltage is reduced by 0.1 - 0.8 V each time, the current is reduced by 0.1 - 0.8 A, and the heat preservation is 5 - 25 min.

[0015] According to an embodiment of the present invention, in step S150, after the electro-vacuum consumable furnace is powered off, it is evacuated again. After the cooling time in the furnace is ≥ 2 h, the ingot is removed to obtain the consumable ingot.

[0016] By adopting the above technical scheme, the vacuum consumable smelting method of high nitrogen martensitic heat-resistant steel according to the present invention reduces the loss of nitrogen in the smelting process of high nitrogen martensitic heat-resistant steel by controlling the protective atmosphere of vacuum consumable, and at the same time, by designing the control system of melting rate + droplet and melting rate + voltage, the molten pool is stabilized in the normal smelting process, and good thermal capping can be achieved in the filling smelting process, effectively avoiding the component segregation of the consumable ingot, the pores and the loose shrinkage cavity at the head of the ingot, and improving the solidification quality and yield rate of the consumable ingot. The method is simple and efficient, and can achieve high-quality and stable production of high nitrogen martensitic heat-resistant steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention 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, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the steps of a vacuum consumable melting method for high nitrogen martensitic heat-resistant steel according to an embodiment of the present invention; Figure 2 This is a metallographic diagram of a consumable ingot obtained according to Example 1 of the present invention; Figure 3 This is the metallographic diagram of the consumable ingot obtained in the comparative example. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] It should be understood that the embodiments of the present invention shown in the exemplary embodiments are only illustrative. Although only a few embodiments are described in detail in the present invention, it is easy for those skilled in the art to appreciate that multiple modifications are feasible without actually departing from the teaching of the subject matter of the present invention. Accordingly, all such modifications should be included within the scope of the present invention. Without departing from the gist of the present invention, other replacements, modifications, changes and deletions may be made to the design, operating conditions and parameters of the following exemplary embodiments.

[0021] The present invention provides a vacuum consumable melting method for high nitrogen martensitic heat-resistant steel. Figure 1 As shown, the vacuum consumable melting method of high nitrogen martensitic heat-resistant steel according to one embodiment of the present invention generally includes the following steps: Step S110, preparing a consumable electrode and loading it into an electric vacuum consumable furnace; Step S120: Evacuate the electro-vacuum consumable furnace, and then fill it with a protective gas. Step S130: After starting the arc by electrifying, a molten pool is formed, and the first-stage smelting begins. Step S140: By weight percentage, when 20% - 30% of the consumable electrode remains, the second-stage smelting begins, where the second-stage smelting is filling smelting. Step S150: After smelting is completed, cool and remove the ingot to obtain a consumable ingot.

[0022] Step S110 can obtain a consumable electrode through electric furnace smelting + argon oxygen decarburization (AOD) + ladle furnace refining (LF) or vacuum induction melting method. In an embodiment of the present invention, the consumable electrode can be composed of chemical components with the following weight percentages: 0.05% - 0.15% C, 0.5% - 1.4% Mn, 0.5% - 4% Ni, 9% - 13% Cr, 0.5% - 3% Mo, 0.1% - 1% V, 0.01% - 0.08% N, 0.1% - 0.8% Si, 0.002% - 0.005% P, 0.001% - 0.003% S, and the balance is Fe and inevitable impurities. The specific component design of the consumable electrode needs to be determined by comprehensively considering material properties, process characteristics, and final application requirements. In other embodiments, those skilled in the art can use the teachings disclosed herein to seek the required characteristics and appropriately change the values of each element. It should be understood that the use of a numerical range represented by endpoints includes all numbers within that range and any range within that range. Taking C as an example, 0.05% - 0.15% can include 0.05%, 0.10%, 0.12%, 0.13%, 0.15%, and so on.

[0023] Preferably, the consumable electrode can be subjected to capping and surface peeling before being loaded into the electro-vacuum consumable furnace to prevent unstable molten pool and oxygen increase in the consumable ingot during vacuum consumable smelting, thereby reducing the solidification quality and cleanliness of the consumable ingot.

[0024] In step S120, first evacuate the electro-vacuum consumable furnace to below 1 Pa, and then fill it with dry nitrogen to prevent air from increasing the oxygen and hydrogen content of the consumable ingot, and at the same time inhibit the volatilization of nitrogen during the smelting process, improving the nitrogen recovery rate and composition uniformity. In actual operation, excessive filling of dry nitrogen will cause unstable molten pool during normal smelting, affecting the smelting quality, while too little filling of dry nitrogen will not achieve the effect of controlling the nitrogen content of the consumable ingot. In an embodiment of the present invention, according to the steel liquid composition and the smelting characteristics of the consumable furnace, the preferably filled dry nitrogen pressure is 5 - 20 Pa.

[0025] In step S130, the control system of melting speed + number of molten droplets is adopted during the first stage of smelting. Melting speed refers to the melting rate of the consumable electrode during vacuum consumable smelting, which can directly affect the depth of the molten pool, solidification behavior and component distribution. Too high a melting speed will lead to too deep a molten pool and increase the risk of segregation; while too low a melting speed may reduce production efficiency. In an embodiment of the present invention, the melting speed is preferably controlled to be 4.0~6.5kg / min. The number of molten droplets refers to the number of molten droplets per unit time during vacuum consumable smelting, which affects the temperature distribution and solidification behavior of the molten pool. Too high a number of molten droplets may cause the temperature of the molten pool to fluctuate, while too low a number of molten droplets may affect the fluidity of the molten pool. In an embodiment of the present invention, the number of molten droplets is preferably controlled to be 1~10 (1 / s). The present invention can achieve stable melting speed, active molten pool to the edge, and stable molten pool state in the smelting process through the coordinated control of melting speed and number of molten droplets, which is conducive to preventing segregation of molten steel components, improving the ability to remove inclusions, avoiding the generation of pores in consumable ingots, and improving the solidification quality of consumable ingots.

[0026] In step S140, the second stage of smelting adopts a control system of melting speed + voltage, and is carried out in a low voltage, low current and low melting speed manner. The smelting current can directly affect the molten pool temperature, melting speed and arc stability. Appropriate current can maintain a stable arc and molten pool depth, promote molten pool convection to reduce element segregation, and avoid excessive volatilization of nitrogen, retaining the required nitrogen content. Voltage affects arc length, molten pool shape and energy input. In an embodiment of the present invention, the second stage can be filled in multiple stages, the current is controlled at 8.0~4.0A, the voltage is controlled at 24.0~21.0V, the melting speed is controlled at 4.0~1.0kg / min, the voltage and current are reduced step by step, the voltage is reduced by 0.1~0.6V each time, the current is reduced by 0.2~0.8A, and the temperature is kept for 5~25min. The second stage of smelting is controlled by the coordinated control of current and voltage, and a reasonable filling smelting process is adopted, which can effectively improve the loose shrinkage hole at the head of the consumable ingot and improve the yield rate.

[0027] In an embodiment of the present invention, in step S150, the electric vacuum consumable furnace is evacuated again after power failure, and the ingot is removed to obtain the consumable ingot after the cooling time in the furnace is ≥2h.

[0028] The following are specific embodiments of the vacuum consumable melting method for high nitrogen martensitic heat-resistant steel according to the present invention and its specific process parameters.

[0029] The specific chemical composition of the consumable electrodes prepared in Examples 1-5 is shown in Table 1: Table 1 Chemical composition of consumable electrodes in various embodiments, the balance being iron (wt.%)

[0030] Embodiment 1: The present embodiment discloses a vacuum consumable melting method for high nitrogen martensitic heat-resistant steel, comprising the following steps: Step S110: First, obtain the consumable electrode required for vacuum consumable melting through vacuum induction smelting. Then, cut off the top and peel the surface, and load it into the vacuum consumable furnace.

[0031] Step S120: Evacuate the vacuum consumable furnace to below 1 Pa, and then fill it with 15 Pa of dry nitrogen. Step S130: After starting the arc and forming a molten pool by electrification, start normal melting. The melting rate is controlled at 4.0 - 5.5 kg / min, and the number of molten droplets is 1 - 10 (1 / s). Step S140: When the weight of the remaining consumable electrode ingot is 25%, start filling and melting. Step S150: After the smelting is completed, cool the furnace for 2.5 h and then remove the ingot to obtain a Φ400 mm consumable ingot.

[0032] Among them, Step S140 can be carried out in 6 levels for filling and melting. The melting rate is controlled at 3.0 - 1.0 kg / min, and the voltage and current are gradually reduced. Specifically: Step S141: Reduce the current to 23.5 V, the current is 7 A, and keep it for 5 min. Step S142: Reduce the current to 22.8 V, the current is 6.3 A, and keep it for 10 min. Step S143: Reduce the current to 22.2 V, the current is 5.7 A, and keep it for 15 min. Step S144: Reduce the current to 21.6 V, the current is 5.1 A, and keep it for 20 min. Step S145: Reduce the current to 21.2 V, the current is 4.7 A, and keep it for 20 min. Step S146: Reduce the current to 21.0 V, the current is 4.5 A, and keep it for 10 min.

[0033] Example 2: A vacuum consumable melting method for high-nitrogen martensitic heat-resistant steel disclosed in this example includes the following steps: Step S110: First, obtain the consumable electrode required for vacuum consumable melting through electric furnace + AOD + LF smelting. Then, cut off the top and peel the surface, and load it into the vacuum consumable furnace. Step S120: Evacuate the vacuum consumable furnace to below 1 Pa, and then fill it with 18 Pa of dry nitrogen. Step S130: After starting the arc and forming a molten pool by electrification, start normal melting. The melting rate is controlled at 4.5 - 6.0 kg / min, and the number of molten droplets is 2 - 12 (1 / s). Step S140: When the weight of the remaining consumable electrode ingot is 25%, start filling and melting. Step S150: After smelting is completed, the ingot is cooled in the furnace for 2.5 h and then the ingot is removed to obtain a Φ450 mm consumable ingot.

[0034] Among them, step S140 can be carried out in 6 levels for filling and smelting, the melting rate is controlled at 3.5 - 1.5 kg / min, and the voltage and current are gradually reduced. Specifically: Step S141: Reduce the current to 23.3 V, the current is 6.8 A, and keep it for 5 min; Step S142: Reduce the current to 22.7 V, the current is 6.2 A, and keep it for 10 min; Step S143: Reduce the current to 22.2 V, the current is 5.7 A, and keep it for 15 min; Step S144: Reduce the current to 21.7 V, the current is 5.2 A, and keep it for 20 min; Step S145: Reduce the current to 21.3 V, the current is 4.8 A, and keep it for 20 min; Step S146: Reduce the current to 21.0 V, the current is 4.5 A, and keep it for 10 min.

[0035] Example 3: A vacuum consumable melting method of high nitrogen martensitic heat-resistant steel disclosed in this example includes the following steps: Step S110: First, obtain the consumable electrode required for vacuum consumable by smelting with an electric furnace + AOD + LF, then cut off the ingot head and peel the surface, and then load it into the electric vacuum consumable furnace; Step S120: Vacuumize the vacuum consumable furnace to below 1 Pa, and then fill it with 20 Pa of dry nitrogen; Step S130: After the electric arc is started and a molten pool is formed, start normal smelting, the melting rate is controlled at 5.0 - 6.5 kg / min, and the number of molten droplets is 1 - 13 (1 / s); Step S140: When the weight of the remaining consumable electrode ingot is 28%, start filling and smelting; Step S150: After smelting is completed, the ingot is cooled in the furnace for 3 h and then the ingot is removed to obtain a Φ500 mm consumable ingot.

[0036] Among them, step S140 can be carried out in 6 levels for filling and smelting, the melting rate is controlled at 4.0 - 1.5 kg / min, and the voltage and current are gradually reduced. Specifically: Step S141: Reduce the current to 24.0 V, the current is 7.8 A, and keep it for 10 min; Step S142: Reduce the current to 23.2 V, the current is 7.0 A, and keep it for 15 min; Step S143: Reduce the current to 22.5 V, the current is 6.3 A, and keep it for 20 min; Step S144: Reduce the current to 21.9V, with the current being 5.7A, and maintain for 25 min; Step S145: Reduce the current to 21.4V, with the current being 5.2A, and maintain for 15 min; Step S146: Reduce the current to 21.1V, with the current being 5.0A, and maintain for 7 min.

[0037] Example 4: A vacuum consumable melting method for a high-nitrogen martensitic heat-resistant steel disclosed in this example includes the following steps: Step S110: First, obtain the consumable electrode required for vacuum consumable through electric furnace + AOD + LF smelting, then cut off the ingot head and peel the surface, and load it into the electric vacuum consumable furnace; Step S120: Evacuate the vacuum consumable furnace to below 1 Pa, and then fill it with 12 Pa of dry nitrogen; Step S130: After the electric arc is struck and a molten pool is formed, start normal smelting, control the melting rate at 4.0 - 6.0 kg / min, and the number of molten droplets at 1 - 12 (1 / s); Step S140: When the weight of the remaining consumable electrode ingot is 20%, start the filling smelting; Step S150: After the smelting is completed, cool the furnace for 2 h and then remove the ingot to obtain a Φ450 mm consumable ingot.

[0038] Among them, Step S140 can be carried out in 5 levels of filling smelting, control the melting rate at 3.5 - 1.5 kg / min, and gradually reduce the voltage and current. Specifically: Step S141: Reduce the current to 23.0V, with the current being 7.0A, and maintain for 5 min; Step S142: Reduce the current to 22.4V, with the current being 6.5A, and maintain for 10 min; Step S143: Reduce the current to 21.8V, with the current being 6.0A, and maintain for 15 min; Step S144: Reduce the current to 21.4V, with the current being 5.5A, and maintain for 15 min; Step S145: Reduce the current to 21.0V, with the current being 5.0A, and maintain for 10 min.

[0039] Example 5: A vacuum consumable melting method for a high-nitrogen martensitic heat-resistant steel disclosed in this example includes the following steps: Step S110: First, obtain the consumable electrode required for vacuum consumable through electric furnace + AOD + LF smelting, then cut off the ingot head and peel the surface, and load it into the electric vacuum consumable furnace; Step S120: Evacuate the vacuum consumable furnace to below 1 Pa, and then fill it with dry nitrogen at 8 Pa; Step S130: After starting the arc by electrification to form a molten pool, start normal melting. Control the melting rate at 5.0 - 6.5 kg / min and the number of molten droplets at 1 - 15 (1 / s); Step S140: When the remaining weight of the consumable electrode ingot is 30%, start filling melting; Step S150: After the smelting is completed, cool the furnace for 3.5 h and then remove the ingot to obtain a Φ580 mm consumable ingot.

[0040] Among them, Step S140 can be carried out in 7 levels of filling melting. Control the melting rate at 4.0 - 1.0 kg / min, and gradually reduce the voltage and current. Specifically: Step S141: Reduce the current to 24.0 V, the current is 7.0 A, and keep it for 10 min; Step S142: Reduce the current to 23.4 V, the current is 6.4 A, and keep it for 10 min; Step S143: Reduce the current to 23.8 V, the current is 5.8 A, and keep it for 15 min; Step S144: Reduce the current to 23.2 V, the current is 5.3 A, and keep it for 25 min; Step S145: Reduce the current to 22.6 V, the current is 4.8 A, and keep it for 20 min; Step S146: Reduce the current to 22.1 V, the current is 4.4 A, and keep it for 20 min; Step S147: Reduce the current to 21.7 V, the current is 4.0 A, and keep it for 10 min.

[0041] Comparative example: First, obtain the consumable electrode required for vacuum consumable by smelting with an electric furnace + AOD + LF. Then cut off the cap and peel the surface, and load it into the electro-vacuum consumable furnace. Evacuate the vacuum consumable furnace to below 1 Pa. After starting the arc by electrification to form a molten pool, start normal melting. Control the melting rate at 6.5 - 7.5 kg / min. When the remaining weight of the consumable electrode ingot is 32%, start filling melting. Control the melting rate at 2 - 4 kg / min during filling. After the smelting is completed, cool the furnace for 2 h and then remove the ingot to obtain a Φ450 mm consumable ingot.

[0042] Detect the main chemical compositions of the A end and H end of the high-nitrogen martensitic heat-resistant steel consumable ingots obtained in Examples 1 - 5. At the same time, detect the main chemical compositions of both ends of the steel ingot of the high-nitrogen martensitic heat-resistant steel obtained in the comparative example. The results are shown in Table 2: Table 2 Chemical Compositions of Both Ends of Electrode Rods, Consumable Ingots and Comparative Examples in Each Example (wt.%)

[0043] in conclusion The inclusion rating of the high nitrogen martensitic heat-resistant steel ingots obtained in Examples 1-5 and the comparative example is shown in Table 3: Table 3 Inclusion rating results

[0044] contrast Figure 2 The metallographic diagram of the consumable ingot obtained in Example 1 of the present invention is shown in FIG. Figure 3 The metallographic image of the consumable ingot obtained in the comparative example shows that the structure obtained in the embodiment is dense and has no solidification defects, while the structure obtained in the comparative example is loose and has serious shrinkage defects.

[0045] The present invention controls the protective atmosphere of vacuum consumable smelting and optimizes the smelting system, thereby reducing the escape of nitrogen during the smelting process, effectively improving the component segregation and solidification quality of the consumable ingot, and improving the cleanliness of the alloy. At the same time, it reduces the shrinkage cavity and loose area at the shrinkage feeding end, improves the alloy yield rate, and can achieve high-quality and stable production of high-nitrogen martensitic heat-resistant steel.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. If the present invention is modified or replaced by equivalents without departing from the spirit and scope of the present invention, it should be included in the protection scope of the claims of the present invention.

[0047] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention is limited to these examples; under the idea of ​​the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A vacuum consumable melting method for a high-nitrogen martensitic heat-resistant steel, characterized in that, It includes the following steps: S110, prepare a consumable electrode and load it into an electric vacuum consumable furnace; S120, evacuate the electric vacuum consumable furnace, and then fill it with a protective gas; S130, form a molten pool after starting the arc by energization, and start the first-stage smelting; S140, by weight percentage, when 20% - 30% of the consumable electrode remains, start the second-stage smelting, wherein the second-stage smelting is filling smelting; S150, after smelting is completed, cool and remove the ingot to obtain a consumable ingot.

2. The method according to claim 1, wherein In step S110, the consumable electrode is obtained by electric furnace smelting + argon oxygen decarburization + ladle refining or vacuum induction melting method; Wherein, the consumable electrode is composed of chemical components with the following weight percentages: 0.08% - 0.15% C, 0.5% - 1.4% Mn, 2% - 4% Ni, 9% - 12% Cr, 1.5% - 3% Mo, 0.2% - 1% V, 0.06% - 0.1% N, 0.11% - 0.14% Si, 0.0032% - 0.0045% P, 0.0019% - 0.002% S, and the balance is Fe and inevitable impurities.

3. The method according to claim 1, wherein In step S110, the consumable electrode is subjected to cutting the cap and surface skimming before being loaded into the electric vacuum consumable furnace.

4. The method according to claim 1, wherein In step S120, first evacuate the inside of the electric vacuum consumable furnace to below 1 Pa, and then fill it with dry nitrogen.

5. The method according to claim 4, wherein In step S120, the pressure of the dry nitrogen filled is 5 - 20 Pa.

6. The method according to claim 1, wherein In step S130, a control system of melting rate + number of droplets is adopted during the first-stage smelting.

7. The method according to claim 6, wherein In step S130, control the melting rate to be 4.0 - 6.5 kg / min, and the number of droplets to be 1 - 15 (1 / s).

8. The method according to claim 1, wherein In step S140, a control system of melting rate + voltage is adopted during the second-stage smelting.

9. The method according to claim 8, wherein In step S140, the second-stage smelting is filled in multiple stages, the current is controlled at 8.0 - 4.0 A, the voltage is controlled at 24.0 - 21.0 V, the melting rate is controlled at 4.0 - 1.0 kg / min, the voltage and current are gradually reduced, the voltage is reduced by 0.1 - 0.6 V each time, the current is reduced by 0.2 - 0.8 A, and the heat preservation is 5 - 25 min.

10. The method according to claim 9, wherein In step S150, after the electric vacuum consumable furnace is powered off, evacuate it again, and after the cooling time in the furnace is ≥ 2 h, remove the ingot to obtain a consumable ingot.

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