Slag system for ingot pulling type electroslag remelting nitrogen control austenitic stainless steel, preparation method and use method

Abstract

The invention relates to the technical field of electroslag remelting slag. The invention discloses a special slag system for an ingot pulling type electroslag remelting nitrogen-controlled austenitic stainless steel ingot, which comprises the following components in percentage by mass: 45-50% of CaF2, 25-30% of Al2O3, 15-20% of CaO, 3-6% of MgO, 5-10% of SiO2 and the balance of impurities, and the content of the impurities is less than or equal to 1%. The binary alkalinity CaO / SiO2 is 1.5 to 4; the melting point of the special slag system is 1250-1280 DEG C, the viscosity value of the special slag system at the temperature of 1600 DEG C is 0.044-0.053 Pa.s, and the resistivity of the special slag system at the temperature of 1600 DEG C is 0.51-0.55 omega.cm. According to the slag system, by optimizing the components of the slag system, the physical and chemical properties of the slag system are further improved, the slag-metal reaction is inhibited, and the production process requirements of ingot pulling type electroslag remelting large stainless steel ingots are met. The produced nitrogen-controlled austenitic stainless steel ingot is good in surface quality and free of defects such as obvious pits, slag runners and double skins; and easily oxidized elements Al and Si in the steel in the remelting process are uniformly distributed in the height direction of the cast ingot, so that the uniformity of alloy textures is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of electroslag remelting slag, in particular to a slag system for ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel, a preparation method and a use method. Background Art

[0002] Nitrogen-controlled austenitic stainless steel is an advantageous steel grade developed in recent years. By adding an appropriate amount of N element to the steel, it can not only have the same strength as 304 stainless steel, but also has the intergranular corrosion resistance of 304L stainless steel. It is an ideal material for nuclear reactor internals and nuclear power plant main pipelines. At present, large steel ingots are mostly produced by electroslag remelting technology. The electroslag remelting process technology is mainly divided into two types: fixed type and ingot extraction type. Compared with fixed type electroslag remelting, ingot extraction type electroslag remelting can significantly improve productivity and yield rate when producing large steel ingots. However, there is relative movement between the crystallizer and the steel ingot during the ingot extraction process. When the slag system composition is not designed reasonably, steel leakage and slag leakage accidents are prone to occur, and there are defects such as heavy skin and slag inclusions on the surface of the steel ingot.

[0003] Traditional electroslag remelting slag systems, such as 70% CaF2+30% Al2O3, 60% CaF2+20% CaO+20% Al2O3, 40% CaF2+30% CaO+30% Al2O3, will cause the slag high temperature toughness to deteriorate due to crystallization during the cooling process; at the same time, as the temperature drops to near its melting point, the viscosity will increase sharply, which is not conducive to the surface quality of the ingot. The slag system for ingot-drawing electroslag remelting must not only play a refining role, but also have certain lubricity and plasticity, so the traditional ternary slag system is not suitable for the process conditions of ingot-drawing electroslag.

[0004] Therefore, it is an urgent problem to develop a slag system for producing nitrogen-controlled austenitic stainless steel by ingot extraction electroslag remelting, so that the prepared slag meets the characteristics of low melting point, low viscosity and high resistivity, while ensuring that the easily oxidized elements Al and Si in the steel are evenly distributed along the height direction of the ingot, and produce good internal and external surface quality. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the existing technical problems and the requirements for slag systems, the purpose of the present invention is to develop a slag system for producing nitrogen-controlled austenitic stainless steel by withdrawing ingot type electroslag remelting, so that the prepared slag has the characteristics of low melting point, low viscosity and high resistivity, while ensuring that the easily oxidized elements Al and Si in the steel are evenly distributed along the height direction of the ingot, producing the characteristics of good internal and external surface quality.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] On the one hand, the present invention provides a slag system for ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel, the components of the slag system are, by mass percentage, CaF2: 45% to 50%, Al2O3: 25% to 30%, CaO: 15% to 20%, MgO: 3% to 6%, SiO2: 5% to 10%, and the remainder is impurities, the impurity content is ≤1%, and the binary basicity CaO / SiO2 is 1.5 to 4.

[0010] In some embodiments, the aforementioned slag system for the ingot extraction electroslag remelting of nitrogen-controlled austenitic stainless steel has a melting point of 1250-1280°C.

[0011] In some embodiments, the aforementioned slag system for the ingot extraction type electroslag remelting of nitrogen-controlled austenitic stainless steel has a viscosity of 0.044-0.053 Pa·s when the surface temperature of the slag system is 1600° C.

[0012] In some embodiments, the slag system used in the aforementioned ingot extraction electroslag remelting of nitrogen-controlled austenitic stainless steel has a resistivity of 0.51-0.55 Ω·cm at 1600°C.

[0013] In some embodiments, the aforementioned slag system for the ingot-drawing electroslag remelting of nitrogen-controlled austenitic stainless steel comprises: CaF2: 48-50%, Al2O3: 25%-27%, CaO: 15%-17%, MgO: 3%-4%, SiO2: 6%-8%, and impurity content ≤1% in percentage by mass; wherein the melting point of the slag system is 1260-1270°C, and when the surface temperature of the slag system is 1600°C, its viscosity value is 0.047-0.051 Pa·s, and its resistivity is 0.52-0.54Ω·cm.

[0014] On the other hand, the present invention also provides a method for preparing a slag system for ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel, which comprises the following steps: mixing quicklime, alumina, refined fluorite, fused magnesia and silica in proportion, melting and stirring evenly, smelting at 1520-1570°C for more than 30 minutes, then pouring it into a water-cooled slag tray made of steel plate, and after cooling to room temperature, breaking it into small pieces with a particle size of about 5-10 mm to make a first slag.

[0015] In another aspect, the present invention provides a method for using a slag system for nitrogen-controlled austenitic stainless steel by ingot extraction electroslag remelting, comprising:

[0016] Step 1: Place the first molten slag prepared from the slag system into a baking furnace and heat it to 600-800° C., keep it warm and bake it for 8-10 hours before use;

[0017] Step 2: placing the first molten slag that has been heat-insulated and baked into a slag melting furnace and heating it to above 1600° C. and refining it for 20 minutes to obtain the first liquid slag;

[0018] Step 3: After pouring the first liquid slag into the electroslag furnace crystallizer, insert the consumable electrode to be remelted into the crystallizer and energize it, so that the consumable electrode contacts the slag to form a power circuit for electroslag remelting of nitrogen-controlled austenitic stainless steel. After the consumable electrode melts to form a molten pool, the ingot extraction operation begins. The smelting process is carried out under the protection of high-purity argon gas.

[0019] (III) Beneficial effects

[0020] The beneficial effects of the present invention are:

[0021] (1) The slag system for the ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel of the present invention optimizes the slag system composition so that the prepared slag has a lower melting point and a relatively gentle viscosity change with temperature, making the electroslag ingot easy to solidify and form, and effectively reducing or eliminating the surface defects of the electroslag ingot. The slag system has the advantages of high resistivity and good fluidity, which can effectively inhibit the burning of Si in the steel and control the uniform distribution of the easily oxidized elements Al and Si in the steel along the height direction of the ingot, which not only ensures the uniformity of the alloy structure, but also helps to save resources and reduce costs.

[0022] (2) The slag for the ingot-drawing electroslag remelting of nitrogen-controlled austenitic stainless steel of the present invention is based on fluorite CaF2, and its content is 45%-50%, which is beneficial to lowering the melting point of the prepared slag to ensure the ingot molding, and at the same time can reduce the viscosity and surface tension of the slag at high temperature, ensuring good contact between slag and gold and sufficient reaction.

[0023] (3) Adding 25%-30% Al2O3 to the slag system can increase the resistivity of the slag, increase the slag temperature, increase the slag skin strength, improve production efficiency and reduce energy consumption. Adding 15%-20% CaO to the slag system can increase the optical basicity of the slag, thereby obtaining a good electroslag remelting desulfurization effect and effectively reducing the harmful elements S and P content in the steel. Adding 3%-6% MgO to the slag system forms a film on the surface of the liquid slag, reduces the permeability of oxygen and nitrogen in the liquid slag, and can improve the strength of the solid slag skin, which is conducive to the smooth progress of electroslag remelting of ingots. Adding 5%-10% SiO2 to the slag system can reduce the melting point of the slag, make the viscosity of the slag change more slowly with temperature, and have good high-temperature stability. At the same time, SiO2 can form a low-melting-point glass phase, which can inhibit the formation and growth of other mineral phases, improve the high-temperature plasticity and strength of the slag skin, and ensure the smooth progress of the ingot extraction operation. At the same time, adding SiO2 to the slag system can prevent the burning of Si in the steel, which is conducive to controlling the target composition of the electroslag ingot. However, when the SiO2 content is too high, it is easy to increase the O content in the steel by burning Al and reduce the effect of desulfurization and absorption of inclusions. Therefore, it is necessary to control the binary basicity at 1.5-4 to reduce the activity coefficient of SiO2 in the slag and inhibit the burning of easily oxidized elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The temperature-viscosity curve comparison diagram of the slag system in each embodiment of the present invention, the conventional ingot extraction slag system, and the conventional ANF-6 slag system is as follows:

[0025] Figure 2 It is the phase diagram of CaF2-Al2O3-CaO ternary system;

[0026] Figure 3 It is a comparison diagram of the conductivity-temperature curves of the slag system in Example 1 of the present invention, the traditional ingot extraction slag system, and the traditional ANF-6 slag system. DETAILED DESCRIPTION

[0027] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with specific implementation methods.

[0028] The design concept of the slag system for the ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel of the present invention is as follows:

[0029] The slag system designed for electroslag remelting based on the current mainstream calcium fluoride is a fluorine-containing slag system. According to the phase diagram of the CaF2-CaO-Al2O3 ternary slag system, Figure 2As shown, the melting point of the slag containing 45% to 55% CaF2, 15% to 25% CaO, and 15% to 30% Al2O3 is relatively low. Considering that the smelting time of large electroslag ingots is relatively long, increasing the Al2O3 content in the slag system can not only improve the resistivity of the slag, but also improve the slag skin strength. CaO can increase the optical basicity of the slag and inhibit the activity of SiO2, but too much CaO is prone to increase H and O, so the Al2O3 content is preferably determined to be 25%-30%, and the CaO content is preferably determined to be 15%-20%;

[0030] The main function of MgO is to form a semi-solidified film on the surface of the slag pool, reducing the gas permeability of the liquid slag. However, too high MgO content will increase the viscosity and melting point of the slag, so its addition amount needs to be limited to 3%-6%.

[0031] SiO2 can reduce the melting point of slag, making the viscosity of slag change more slowly with temperature and having good high temperature stability. At the same time, SiO2 can form a low melting point glass phase, which can inhibit the formation and growth of other mineral phases, improve the high temperature plasticity and strength of slag skin, and ensure the smooth operation of ingot extraction.

[0032] When designing the slag system for nitrogen-controlled austenitic stainless steel with ingot extraction electroslag remelting, theoretical analysis and actual research results show that the steel contains easily oxidized elements such as Si and Al, and the following reactions will occur at the slag-metal interface:

[0033] 4[Al]+3(FeO)=3[Fe]+(Al2O3)

[0034] [Si] + 2(FeO) = (SiO2) + 2[Fe]

[0035] 3[Si]+2(Al2O3)=3(SiO2)+4[Al]

[0036] The above reaction will cause the Si and Al in the steel to burn out, and the distribution will be uneven along the height direction of the ingot. In order to inhibit the burning out of the easily oxidized elements in the alloy, in addition to using inert protective gas for electroslag remelting of nitrogen-controlled austenitic stainless steel, the slag system composition can also be adjusted and optimized to inhibit the slag-metal reaction, thereby achieving the purpose of reducing the burning out of elements in the steel and avoiding excessive unstable oxides FeO in the slag system. Adding an appropriate amount of SiO2 can control the moving direction and rate of the above chemical equilibrium reaction, thereby ensuring that the easily oxidized elements Al and Si in the stainless steel are evenly distributed along the height direction of the ingot during the remelting process.

[0037] The following is a specific embodiment of the slag system for nitrogen-controlled austenitic stainless steel using the ingot-drawing electroslag remelting of the present invention, through which the scheme, advantages and technical effects of the present invention are further understood.

[0038] Example 1

[0039] The method of producing nitrogen-controlled austenitic stainless steel electroslag ingots by using the slag system of the present invention comprises the following steps.

[0040] (1) Quicklime, industrial alumina, refined fluorite, fused magnesia and silica are mixed in proportion, the slag is electroplated with graphite electrodes in an electric slag furnace and stirred evenly, and smelted at 1520-1570°C for more than 30 minutes.

[0041] (2) It is then poured into a water-cooled slag pan made of steel plate, and after cooling to room temperature, it is crushed into small pieces with a particle size of about 5 to 10 mm using a crusher as the first slag, which is used as the raw material for producing the ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel;

[0042] The chemical composition of the slag is as follows: CaF2: 50.1%, Al2O3: 25.7%, CaO: 15.2%, MgO: 3.02%, SiO2: 5.89%, and impurities: 0.4%. When the slag is at a temperature of 1600°C, the viscosity of the slag is 0.049 Pa.s. Figure 2 shown.

[0043] (3) The above slag is used for ingot extraction electroslag remelting, and the remelting alloy type is nitrogen-controlled austenitic stainless steel, and its composition is shown in Table 1;

[0044] Table 1 Composition requirements of nitrogen-controlled austenitic stainless steel (mass fraction / %)

[0045]

[0046] The melting point of the slag is 1448°C, the Al content in the electrode used for the ingot-drawing electroslag remelting of nitrogen-controlled austenitic stainless steel is 0.030%, and the Si content is 0.37%. The surface of the consumable electrode needs to be polished clean before electroslag remelting.

[0047] (4) The slag is placed in a baking furnace and heated to 600°C for 9 hours.

[0048] (5) The insulated slag is heated to above 1600°C in a slag melting furnace and refined for about 20 minutes to form the first liquid slag, which is then poured into the crystallizer of the electroslag furnace. The consumable electrode to be remelted is inserted into the crystallizer and energized so that the consumable electrode contacts the slag to form a power circuit. Subsequently, the electroslag remelting nitrogen-controlled austenitic stainless steel smelting process is carried out. After the electrode melts to form a molten pool, the ingot extraction operation is started.

[0049] Among them, when carrying out specific electroslag remelting, the amount of pre-melted slag is 430-450kg / furnace of steel, the voltage of the equipment is set to 68-75V, the current is set to 18-20KA, the electrode insertion depth is controlled at 20mm, and the cold water flow rate of the upper crystallizer is controlled at 90m3 / h, the cooling water flow rate of the lower crystallizer is controlled at 140m 3 / h, the cooling water flow rate of the bottom water tank is controlled at 20m 3 / h, the cooling water flow rate of the ingot drawing device is controlled at 10m 3 / h, the metal pool level is measured by a detector. The pulling speed at the beginning of the ingot extraction is 1mm / min, which is gradually increased to a stable extraction speed of 12mm / mins for electroslag remelting, and the electrode melting speed is 1200kg / h until the consumable electrode is melted. The extracted electroslag ingot is kept warm to prevent cracks.

[0050] The chemical composition analysis of O, Al and Si contents at different positions of the finished product is shown in Table 2.

[0051] Table 2 Content of nitrogen-controlled austenitic stainless steel ingot at different positions

[0052]

[0053]

[0054] It can be seen from the table that the contents of the easily oxidizable elements O, Al, and Si in the steel are within the upper and lower limits, meeting the requirements of the steel grade for their contents, and are evenly distributed along the height direction of the ingot. At the same time, the surface quality of the ingot is qualified, and there are no surface defects such as slag grooves, depressions, and ripples. The non-metallic inclusions of the finished product are rated according to the GB / T 10561-2005 method. The coarse and fine inclusions of A, B, C, and D categories are ≤1.5, and the total is ≤3.0. At the same time, the temperature-viscosity curve in this embodiment is as shown in FIG. Figure 1 In the formula, S1 is shown in FIG3 , and the conductivity-temperature curve comparison diagram in this example is shown in FIG3 , wherein S2 is the slag system for traditional ingot extraction electroslag remelting, and S3 is the ANF-6 slag system. It can be seen from the figure that the conductivity of this slag system is lower than that of the other two slag systems, that is to say, the resistivity of this slag system is higher, and it is safer than other slag systems in actual use.

[0055] Example 2

[0056] The method of producing nitrogen-controlled austenitic stainless steel electroslag ingots by using the slag system of the present invention comprises the following steps.

[0057] (1) Quicklime, industrial alumina, refined fluorite, fused magnesia and silica are mixed in proportion, the slag is electroplated with graphite electrodes in an electric slag furnace and stirred evenly, and smelted at 1520-1570°C for more than 30 minutes.

[0058] (2) It is then poured into a water-cooled slag pan made of steel plate, and after cooling to room temperature, it is crushed into small pieces with a particle size of about 5 to 10 mm using a crusher as the first slag, which is used as the raw material for producing ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel.

[0059] The mass percentage of the chemical composition of the above-mentioned special slag system is: CaF2: 47.41%, Al2O3: 25.4%, CaO: 15.1%, MgO: 3.85%, SiO2: 7.82%, and impurities 0.4%. When the slag system is at a temperature of 1600°C, the viscosity of the slag system is 0.050 Pa.s. Figure 2 shown.

[0060] (3) The above slag system is used for ingot extraction electroslag remelting, and the remelting alloy type is nitrogen-controlled austenitic stainless steel, and its composition is shown in Table 3;

[0061] Table 3 Composition requirements of nitrogen-controlled austenitic stainless steel (mass fraction / %)

[0062]

[0063] The melting point of the alloy is 1452°C, and the Al content and Si content of the electrode used in the ingot-drawing electroslag remelting of nitrogen-controlled austenitic stainless steel are 0.031% and 0.41%, respectively. The surface of the consumable electrode is polished clean before electroslag remelting.

[0064] (4) The slag is placed in a baking furnace and heated to 700°C for 10 hours.

[0065] (5) The insulated slag is heated to above 1600°C in a slag melting furnace and refined for about 20 minutes. The liquid slag is then poured into the crystallizer of the electroslag furnace. The consumable electrode to be remelted is inserted into the crystallizer and energized so that the consumable electrode contacts the slag to form a power circuit. The electroslag remelting nitrogen-controlled austenitic stainless steel is then carried out. After the electrode melts to form a molten pool, the ingot extraction operation is started.

[0066] Compared with Example 1, the difference is:

[0067] When performing specific electroslag remelting, the amount of pre-melted slag is 450-470kg / furnace of steel, the voltage of the equipment is set to 68-75V, the current is set to 18-20KA, the electrode insertion depth is controlled at 20mm, and the cold water flow rate of the upper crystallizer is controlled at 90m 3 / h, the cooling water flow rate of the lower crystallizer is controlled at 140m 3 / h, the cooling water flow rate of the bottom water tank is controlled at 20m 3 / h, the cooling water flow rate of the ingot drawing device is controlled at 10m 3 / h, the metal pool level is measured by a detector. The pulling speed at the beginning of the ingot extraction is 1mm / min, which is gradually increased to a stable extraction speed of 12mm / mins for electroslag remelting, and the electrode melting speed is 1200kg / h until the consumable electrode is melted. The extracted electroslag ingot is kept warm to prevent cracks.

[0068] The chemical composition analysis of O, Al and Si contents at different positions of the finished product is shown in Table 4.

[0069] Table 4 Content of nitrogen-controlled austenitic stainless steel ingot at different positions

[0070]

[0071] It can be seen from the table that the contents of the easily oxidizable elements O, Al, and Si in the steel are within the upper and lower limits, meeting the requirements of the steel grade for their contents, and are evenly distributed along the height direction of the ingot. At the same time, the surface quality of the ingot is qualified, and there are no surface defects such as slag grooves, depressions, and ripples. The non-metallic inclusions of the finished product are rated according to the GB / T 10561-2005 method. The coarse and fine inclusions of A, B, C, and D categories are ≤1.5, and the total is ≤3.0. At the same time, the temperature-viscosity curve in this embodiment is as shown in FIG. Figure 1 In the formula S2, where .

[0072] From the above embodiments, the slag system for the ingot-drawing electroslag remelting nitrogen-controlled austenitic stainless steel of the present invention optimizes the slag system composition, so that the slag system has a lower melting point, and the viscosity changes more slowly with temperature, so that the electroslag ingot is easy to solidify and form, and the surface defects of the electroslag ingot are effectively reduced or eliminated. Figure 1 S3 is a traditional ingot extraction slag system, specifically 60% CaF2+20% Al2O3+20% CaO slag system, S4 is 70% CaF2+30% Al2O3 slag system, the viscosity changes greatly with temperature, and the electroslag ingot is not stable enough, so the surface of the electroslag ingot is prone to defects. On the other hand, this slag system has the advantages of high resistivity and good fluidity, which not only ensures that the easily oxidized elements Al and Si in the steel are evenly distributed along the height direction of the ingot, but also helps save resources and reduce costs.

Claims

1. A slag system for ingot-drawing electroslag remelting of nitrogen-controlled austenitic stainless steel, characterized in that: The components of the slag system are CaF2: 45%-50%, Al2O3: 25%-30%, CaO: 15%-20%, MgO: 3%-6%, SiO2: 5%-10%, and the remainder is impurities, the impurity content is ≤1%, and the binary basicity CaO / SiO2 is 1.5-4.

2. The slag system for nitrogen-controlled austenitic stainless steel by ingot extraction electroslag remelting according to claim 1, characterized in that: The melting point of the slag system is 1250-1280°C.

3. The slag system for nitrogen-controlled austenitic stainless steel by ingot extraction electroslag remelting according to claim 1, characterized in that: When the surface temperature of the slag system is 1600° C., its viscosity value is 0.044-0.053 Pa·s.

4. The slag system for nitrogen-controlled austenitic stainless steel by ingot extraction electroslag remelting according to claim 1, characterized in that: When the surface temperature of the slag system is 1600°C, the resistivity thereof is 0.51-0.55Ω·cm.

5. The slag system for nitrogen-controlled austenitic stainless steel by withdrawing ingot type electroslag remelting according to claim 1, 2, 3 or 4, characterized in that: The slag system comprises: by mass percentage, CaF2: 48-50%, Al2O3: 25-27%, CaO: 15-17%, MgO: 3-4%, SiO2: 6-8%, and the impurity content is ≤1%; The melting point of the slag system is 1260-1270°C, and when the surface temperature of the slag system is 1600°C, its viscosity is 0.047-0.051 Pa·s, and its resistivity is 0.52-0.54Ω·cm.

6. A method for preparing a slag system for nitrogen-controlled austenitic stainless steel by ingot extraction electroslag remelting, characterized in that: Comprising at least the slag system for nitrogen-controlled austenitic stainless steel using ingot-drawing electroslag remelting as described in any one of claims 1 to 5; The preparation method comprises the following steps: mixing quicklime, alumina, refined fluorite, fused magnesia and silica in proportion, melting and stirring evenly, smelting at 1520-1570°C for more than 30 minutes, then pouring it into a water-cooled slag tray made of steel plate, and after cooling to room temperature, breaking it into small pieces with a particle size of about 5-10 mm to make the first slag.

7. A method for using a slag system for ingot extraction electroslag remelting nitrogen-controlled austenitic stainless steel, characterized in that: Comprising at least the slag system for nitrogen-controlled austenitic stainless steel using ingot-drawing electroslag remelting as described in any one of claims 1 to 5; The method of use comprises the steps of: placing the first molten slag prepared from the slag system into a baking furnace, heating it to 600-800° C., and baking it for 8-10 hours for later use; Step 2: placing the first molten slag that has been kept warm and baked into a slag melting furnace and heating it to above 1600° C. and refining it for 20 minutes to obtain a first liquid slag; Step 3: After pouring the first liquid slag into the electroslag furnace crystallizer, insert the consumable electrode to be remelted into the crystallizer and energize it, so that the consumable electrode contacts the slag to form a power circuit for electroslag remelting of nitrogen-controlled austenitic stainless steel. After the consumable electrode melts to form a molten pool, the ingot extraction operation begins. The smelting process is carried out under the protection of high-purity argon gas.

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