A power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy and its use method

Abstract

The present invention relates to a power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy and a method for using the same, belonging to the technical field of electroslag special metallurgy, and improving the problem of poor stability and easy fluctuation of the components of the electroslag smelting slag system in the prior art. The mass percentage of each component in the power-saving desulfurization slag system of the present invention is: CaF2: 49.5% to 49.9%, Al2O3: 25.1% to 25.9%, CaO: 19.1% to 19.9%, MgO: 3.4% to 3.7%, ZrO2: 0.46% to 0.49%, TiO2: 0.46% to 0.49%, B2O3: 0.01% to 0.03%, SiO2 <0.5%, and the rest are impurities. The slag system of the present invention has a good desulfurization effect, and the slag system has good metallurgical performance stability. When the slag system of the present invention is used to electroslag remelt C-HRA-3 alloy, the steel ingot elements are evenly distributed, and it has the advantages of saving electric energy and improving production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of electroslag special metallurgy, and in particular to an electricity-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy and a use method thereof. Background Art

[0002] C-HRA-3 heat-resistant alloy is a solid solution strengthened nickel-based heat-resistant alloy independently developed by my country. C-HRA-3 heat-resistant alloy is one of the candidate materials for large-diameter thick-walled tubes of 700℃ advanced ultra-supercritical coal-fired power station boilers. The melting temperature range of C-HRA-3 heat-resistant alloy is about 1260~1470℃. Among them, during the electroslag smelting process, due to the high oxygen potential of alloying elements such as zirconium, aluminum, and titanium, C-HRA-3 heat-resistant alloy is easy to react with oxygen and affect the element composition control. The existing C-HRA-3 heat-resistant alloy used in the electroslag smelting process has poor component stability, is prone to fluctuations, and has poor desulfurization effect. Summary of the invention

[0003] In view of the above background technology analysis, an embodiment of the present invention aims to provide a power-saving desulfurization slag system for electroslag remelting of C-HRA-3 alloy and a method of using the same, so as to solve one of the following technical problems: the existing electroslag smelting slag system has poor component stability, is prone to fluctuations, and has poor desulfurization effect.

[0004] The purpose of the present invention is mainly achieved through the following technical solutions:

[0005] On the one hand, the present invention provides a power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy, and the mass percentage of each component in the power-saving desulfurization slag system is: CaF2: 49.5%~49.9%, Al2O3: 25.1%~25.9%, CaO: 19.1%~19.9%, MgO: 3.4%~3.7%, ZrO2: 0.46%~0.49%, TiO2: 0.46%~0.49%, B2O3: 0.01%~0.03%, SiO2<0.5%, and the rest are impurities.

[0006] Furthermore, in the power-saving desulfurization slag system, the ratio of the Al2O3 content to 0.8% is 31.375-32.375.

[0007] Furthermore, in the power-saving desulfurization slag system, the ratio of ZrO2 content to 0.03% is 15.3-16.4.

[0008] Furthermore, in the power-saving desulfurization slag system, the ratio of TiO2 content to 0.3% is 1.53-1.64.

[0009] Furthermore, in the power-saving desulfurization slag system, the ratio of the content of B2O3 to 0.002% is 5 to 15.

[0010] Furthermore, in the power-saving desulfurization slag system, the ratio of the MgO content to the minimum content of 0.005% of the component Mg in the alloy is 680-740.

[0011] Furthermore, in the power-saving desulfurization slag system, the ratio of CaO content to 0.002% is 9550-9950.

[0012] Furthermore, the melting point of the power-saving desulfurization slag system is 1290-1400°C; at 1700-1800°C, the density is 2.58-2.63 g / cm 3 , viscosity 0.01~0.02Pa·s, conductivity 2.7~3.3S / cm.

[0013] The present invention also provides a method for using the above-mentioned power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy, comprising the following steps:

[0014] Step 1: using industrial pure CaF2, CaO, Al2O3, MgO, ZrO2, TiO2 and B2O3 to prepare a slag system according to mass percentage;

[0015] Step 2: pre-melting the prepared slag system, and then cooling the pre-melted slag, breaking it, and sealing it for storage;

[0016] Step 3: The slag system obtained in step 2 is used for smelting of C-HRA-3 alloy.

[0017] Furthermore, in step 3, an electroslag furnace with an inert gas atmosphere protection function is used for smelting, and the smelting process includes:

[0018] Step 301: Loading smelting electrode rods into the electroslag furnace crystallizer, the electrode composition meets the composition requirements of C-HRA-3 heat-resistant alloy; checking and testing the water, electricity and gas systems of the electroslag furnace equipment, and preparing them for use;

[0019] Step 302: Before using the electroslag smelting, pour the slag into a slag mixing hopper, add aluminum particles, stir and mix evenly, and set aside;

[0020] Step 303: After the arc of the electroslag furnace is started, the slag mixed with aluminum particles is added into the electroslag furnace crystallizer for electroslag smelting.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The slag system of the present invention can balance the easily oxidized and burned Zr, Ti, B and other elements in the metal molten pool by adding ZrO2, TiO2, and B2O3, reduce the burning of Zr, Ti, and B, and ensure the narrow composition control of Zr, Ti, B and other elements in the steel slag; balance the Ca content in the metal molten pool by adding CaO, and balance the Mg content in the metal molten pool by adding MgO; balance the Al content in the metal molten pool by relying on Al2O3 in the slag and adding aluminum particles to the slag for deoxidation when the slag system is used; the slag system of the present invention contains a relatively high CaO content, reaching 1 9.1% to 19.9%, which can achieve a good desulfurization effect and is suitable for smelting special steels and alloys with an S content of ≤0.002% or less; the slag system of the present invention accurately controls the content of each component, and the fluctuation range of the slag system components is small, thereby ensuring the good stability of the slag system metallurgical properties, ensuring that the elements of the steel ingot obtained by electroslag remelting C-HRA-3 alloy are evenly distributed in the length direction and meet the control standard, the surface quality is good, the slag skin thickness is relatively uniformly distributed, and the average slag skin thickness in the middle section of the steel ingot is ≤2mm, for example ≤1.3mm.

[0023] 2. The slag system of the present invention is pre-melted during use to form relatively stable compounds between the slag system components, and large component fluctuations and performance differences are not likely to occur during the electroslag smelting process.

[0024] 3. In the slag system of the present invention, the addition amount of CaF2 is relatively low, which can reduce environmental pollution and harm to human body.

[0025] In the present invention, fine-tuning can be performed based on the slag composition range to achieve more preferred combination solutions, which are considered as the protection scope of the present invention. Some advantages of the present invention may become obvious from the description or be understood through the implementation of the present invention. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described in detail below in conjunction with examples, wherein the examples constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0027] The object of the present invention is to provide a power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy and a method of using the same. Among them, the chemical composition mass percentage of C-HRA-3 heat-resistant alloy is: Cr: 21.0% ~ 23.0%; C: 0.04% ~ 0.07%; Mn ≤ 0.3%; Co: 11.0% ~ 13.0%; Mo: 6.0% ~ 9.0%; Ti: 0.3% ~ 0.5%; Al: 0.8% ~ 1.3%; W: 0.1% ~ 1.0%; B: 0.002% ~ 0.005%; Zr: 0.02% ~ 0.15%; Nb < 0.5%; V ≤ 0.5%; Cu ≤ 0.15%; P < 0.008%; S < 0.002%; N ≤ 0.015%, Mg: 0.005% ~ 0.02%; Ca: ≤ 0.01%; the balance is nickel and unavoidable impurity elements.

[0028] The existing slag systems used for electroslag remelting of C-HRA-3 alloys are mostly roughly adjusted based on production experience, lacking theoretical design rationality. The existing slag systems have poor component stability, are prone to fluctuations, and have poor desulfurization effects; therefore, after in-depth research, the inventors have provided a low-pollution, power-saving, desulfurization slag system for electroslag remelting of C-HRA-3 alloys based on the alloy element system of C-HRA-3 alloys and the thermodynamic phase diagram of the multi-component slag system, according to the element balance and the property matching of the metal material / slag system. The slag system has a stable composition structure, can balance the elements such as Zr and Ti that are easily burned between steel slags, has the advantages of efficient desulfurization and energy saving, and meets the electroslag smelting requirements of C-HRA-3 heat-resistant alloys.

[0029] Specifically, the mass percentage of each component in the above-mentioned power-saving desulfurization slag system used for electroslag remelting C-HRA-3 alloy is: CaF2: 49.5%~49.9%, Al2O3: 25.1%~25.9%, CaO: 19.1%~19.9%, MgO: 3.4%~3.7%, ZrO2: 0.46%~0.49%, TiO2: 0.46%~0.49%, B2O3: 0.01%~0.03%, SiO2<0.5%, and the rest are impurities.

[0030] Specifically, the above-mentioned energy-saving desulfurization slag system used for electroslag remelting C-HRA-3 alloy and the C-HRA-3 alloy material also need to meet the following relationship:

[0031] 1) The ratio of the content of Al2O3 in the above-mentioned power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy to the minimum content of 0.8% of the component Al in the alloy is 31.375-32.375;

[0032] 2) The ratio of the content of ZrO2 in the above-mentioned power-saving desulfurization slag system used for electroslag remelting C-HRA-3 alloy to the minimum content of Zr in the alloy of 0.03% is 15.3-16.4;

[0033] 3) The ratio of the content of TiO2 in the above-mentioned power-saving desulfurization slag system used for electroslag remelting C-HRA-3 alloy to the minimum content of 0.3% of the component Ti in the alloy is 1.53 to 1.64;

[0034] 4) The ratio of the content of B2O3 in the above-mentioned power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy to the minimum content of component B in the alloy of 0.002% is 5 to 15 (for example, 5 to 10);

[0035] 5) The ratio of the content of MgO in the above-mentioned power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy to the minimum content of Mg in the alloy of 0.005% is 680-740 (e.g. 680-730);

[0036] 6) One of the important functions of CaO in the above-mentioned power-saving desulfurization slag system used for electroslag remelting of C-HRA-3 alloy is desulfurization. The ratio of the CaO content in the power-saving desulfurization slag system to the maximum value of 0.002% required for the component S in the alloy is 9550~9950 (for example, 9600~9950).

[0037] After in-depth research, the inventors found that when the above-mentioned correlation control is carried out on Al2O3, ZrO2, TiO2, B2O3, MgO in the above-mentioned power-saving desulfurization slag system and Al, Zr, Ti, B, Mg between the alloys, the contents of the main easily oxidized alloying elements Al, Zr, Ti, B, Mg in the alloy ingot can be guaranteed to be qualified. In addition, the elements such as V, Cr, C, Mn, Co, Mo, W in the alloy are difficult to be oxidized and the desulfurization requirements are met.

[0038] It should be noted that the functions of the components in the above-mentioned power-saving desulfurization slag system are as follows:

[0039] CaF2 in the slag system can reduce the melting point, viscosity and surface tension of the slag. However, compared with other components, CaF2 has a higher conductivity; the role of CaO in the slag system is mainly to increase the basicity of the slag and improve the desulfurization efficiency; Al2O3 in the slag system can significantly reduce the conductivity of the slag, reduce power consumption and improve productivity.

[0040] MgO has two functions in the slag system. First, since the C-HRA-3 heat-resistant alloy has extremely strict requirements on the mass fraction of H, and the CaO content in this slag system is high and easy to absorb hydrogen, a certain amount of MgO needs to be added to the slag system of the present invention to reduce the permeability of H. MgO also has the function of reducing oxygen and nitrogen in the molten pool, ensuring that Mg in the metal molten pool is not completely oxidized; second, MgO can form a semi-solidified film on the surface of the slag pool to reduce the heat loss radiated from the slag surface to the atmosphere.

[0041] The role of ZrO2, TiO2 and B2O3 in the slag system is to balance the Zr, Ti and B elements in the slag system that are easily burned.

[0042] Unlike the existing high-fluorine slag system with a CaF2 mass content of 60% to 70%, the CaF2 used in the present invention is a power-saving desulfurization slag system with a mass content of 49.5% to 49.9%. The CaF2 content in the slag system is reduced, and the CaO and Al2O3 contents are increased. The inventors found in their research that both CaF2 and MgO are related to the viscosity of the slag system. The addition amount of CaF2 is negatively correlated with the viscosity of the slag system. As the addition amount of CaF2 increases, the viscosity of the slag system will decrease. The slag system has a low melting point and viscosity, and good fluidity, which is conducive to the smooth progress of the electroslag remelting process. Therefore, after in-depth research, the present invention accurately controls the addition amounts of CaF2 and MgO in the slag system of the present invention to be 49.5% to 49.9% and 3.4% to 3.7% respectively, ensuring that the viscosity of the slag system of the present invention at 1800°C is ≤0.05Pa·s. When the slag system is smelted under this viscosity, the slag skin on the body of the electroslag ingot is uniform, the average thickness of the slag skin is ≤2mm, and the slag skin and the ingot body are easy to peel off when the electroslag ingot is cooled after smelting.

[0043] Specifically, the melting point of the above-mentioned power-saving desulfurization slag system is 1310-1400°C (e.g., 1340-1380°C); at 1700-1800°C, the density is 2.58-2.63 g / cm 3 , viscosity 0.01-0.02 Pa·s (e.g. 0.01-0.017 Pa·s), conductivity 2.7-3.3 S / cm. The use of this slag system can save 7%-9% of electricity, and can achieve an average slag skin thickness of ≤2mm on the body of the electroslag ingot.

[0044] In the production of C-HRA-3 heat-resistant alloy by electroslag remelting, the physical and chemical properties of the slag system affect the production quality of the steel ingot, as follows:

[0045] (1) Melting point: The melting point of slag will affect the conductivity, viscosity and calorific value of the slag system. Too high or too low melting point is not conducive to physical and chemical reactions such as dephosphorization and desulfurization, and it is also easy to cause internal and surface quality problems of steel ingot products, and metallurgical defects such as cavities, pores and inclusions. The melting point range designed in the present invention is 1290-1400℃, which ensures that the surface quality of the steel ingot is uniform, no pores are generated on the surface, and has a good effect of saving electricity.

[0046] (2) Viscosity: The viscosity of the slag affects the circulation flow rate of the slag. Due to the electromagnetic stirring force, the low-viscosity slag will have a strong stirring effect, which can enhance the fluidity of the slag, facilitate heat transfer, and enhance the diffusion of the reaction interface. In the present invention, the viscosity is ≤0.05Pa·s at 1800°C, which ensures that the steel slag in the smelting has good fluidity, improves the heat and mass transfer efficiency in the furnace, and reduces energy loss. Ensure that the average thickness of the slag skin of the electroslag ingot is less than 2mm.

[0047] (3) Density: The density of the slag system mainly determines the amount of slag used in the electroslag remelting process, the rate and residence time of the melting point passing through the slag layer during the electroslag remelting process, and thus determines the purification effect during the electroslag remelting process, as well as the difficulty of slag-metal separation during the electroslag remelting process. Therefore, the selection of a suitable slag system density has a certain influence on the metallurgical quality of the electroslag remelting process. In the present invention, the density is 2.58-2.63 g / cm at 1800°C. 3 , ensuring uniform quality of the steel ingot and low impurity content, while ensuring better separation between the steel ingot and the electroslag surface.

[0048] (4) Electrical conductivity: The slag pool can be regarded as a resistor in the circuit of the entire electroslag remelting process, providing the required resistance heat for remelting. When the current, voltage and effective area of ​​the slag pool are constant, the distance between the consumable electrode and the molten metal pool is proportional to the conductivity of the slag. If the conductivity is too small, the inter-electrode distance (the distance between the consumable electrode and the molten metal pool) will be shortened. If the inter-electrode distance is too short, the electroslag remelting process will be unstable. At the same time, it will also affect the reaction time of the slag during the falling of the small metal droplets, which is not conducive to the removal of inclusions. In the present invention, the electrical conductivity is 2.7~3.3S / cm at 1800℃, which provides sufficient heat transfer for the electroslag smelting process and ensures the smooth progress of the electroslag smelting process.

[0049] Preferably, the mass percentage of each component in the above-mentioned power-saving desulfurization slag system used for electroslag remelting C-HRA-3 alloy is: CaF2: 49.55%~49.9%, Al2O3: 25.3%~25.9%, CaO: 19.3%~19.9%, MgO: 3.41%~3.68%, ZrO2: 0.46%~0.49%, TiO2: 0.46%~0.49%, B2O3: 0.01%~0.028%, SiO2<0.05%, and the rest are impurities.

[0050] The present invention has been found through hot state experiments and production research to ensure that the composition of the electroslag is stable during a long period of smelting and the slag skin surface is uniform. For example, the content of some components of the slag after use is CaF2: 49.6% to 49.9%, Al2O3: 25.5% to 25.9%, CaO: 19.7% to 19.9%, MgO: 3.4% to 3.5%, ZrO2: 0.47% to 0.49%, TiO2: 0.46% to 0.48%, and B2O3: 0.01% to 0.012%.

[0051] On the other hand, the present invention also provides a method for using the above-mentioned power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy, comprising the following steps:

[0052] Step 1: using industrial pure CaF2, CaO, Al2O3, MgO, ZrO2, TiO2 and B2O3 to prepare a slag system according to mass percentage;

[0053] Step 2: pre-melting the prepared slag system, controlling the target composition of the pre-melted slag within the specified composition range of the slag system of the present invention, cooling to 25-50° C., crushing, and sealing for storage;

[0054] Step 3: The slag system obtained in step 2 is used for smelting of C-HRA-3 alloy.

[0055] Specifically, in the above step 2, the prepared slag system is pre-melted in a heating furnace, the furnace temperature is raised to 1490-1500°C and maintained for 20-35 minutes, the target composition of the slag after pre-melting is controlled within the specified composition range of the present invention, and after cooling to 25-50°C, it is crushed by a crusher to a particle size of ≤0.3cm, and sealed and stored at 10Kg / bag.

[0056] Specifically, in the above step 3, an electroslag furnace with an inert gas atmosphere protection function may be used for smelting, and the smelting process includes:

[0057] Step 301: 2.5t of smelting electrode rods are loaded into the electroslag furnace crystallizer, the electrode composition meets the composition requirements of C-HRA-3 heat-resistant alloy (where Al, Ti, and B are controlled according to the middle and upper limits of C-HRA-3, and Mg and S are controlled according to the middle and lower limits of C-HRA-3), the surface of the electrode rods is polished and peeled, and the surface is glossy and has no oxide layer, and is ready for use; the water, electricity, and gas systems of the electroslag furnace are checked and tested, and are ready for use;

[0058] Step 302: Before using the electroslag smelting, unseal the sealed slag and pour it into the slag mixing hopper, add 100-150g of aluminum particles, stir and mix evenly, and set aside;

[0059] Step 303: After the arc of the electroslag furnace is started, the slag mixed with aluminum particles is added into the electroslag furnace crystallizer for electroslag smelting.

[0060] Specifically, in the above step 303, about 5 to 10 minutes after the arc is energized, the slag mixed with aluminum particles is slowly added to the electroslag furnace crystallizer. The amount of slag added within 30 minutes should not exceed 35 to 45 kg. After the metal molten pool and slag pool are initially established, the remaining slag should be added within 1 to 4 hours. The purpose of the above operation is to avoid the phenomenon of excessive slag inclusion in a short period of time causing difficulty in melting the slag after the metal molten pool and slag pool are formed in the electroslag crystallizer. At the same time, adding slag at a low speed and appropriately extending the slag adding time can delay the short-term oxidation consumption of aluminum particles in the slag to a certain extent.

[0061] Specifically, in the above step 303, during the smelting process, the timing starts from 1 hour after the electroslag furnace is powered on, and 50 to 150 g of aluminum particles are added to the slag of the electroslag crystallizer every 30 minutes until the smelting is completed.

[0062] Specifically, in the above step 3, the design range of the main key process parameters is: electrode diameter is about 375mm, mold diameter is about 435mm, slag layer design is about 150mm, the arc-starting bottom plate thickness of the electroslag furnace crystallizer should reach more than 2.2cm, the power input in the arc-starting stage is about 1400kW, the power input in the steady-state stage is 700~740kW, and the average melting rate is about 4.4kg / min.

[0063] Specifically, the smelting effect of the above step 3 is: after smelting, the elements in the length direction of the steel ingot are evenly distributed and meet the control standard, the surface quality is good, the slag skin thickness is relatively evenly distributed, and the average slag skin thickness in the middle section of the steel ingot is ≤1.4mm.

[0064] Example 1

[0065] The present embodiment provides a power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy, and the mass percentage of each component in the power-saving desulfurization slag system is: CaF2: 49.5% to 49.9%, Al2O3: 25.1% to 25.9%, CaO: 19.1% to 19.9%, MgO: 3.4% to 3.7%, ZrO2: 0.46% to 0.49%, TiO2: 0.46% to 0.49%, B2O3: 0.01% to 0.03%, SiO2 <0.5%, and the rest are impurities. The specific components of the slag system are shown in Table 1 below.

[0066] The basic physical properties of the power-saving desulfurization slag system in this embodiment are as follows: the melting point is 1340-1380°C; at 1700-1800°C, the density is 2.59-2.63 g / cm 3 , viscosity 0.01~0.017Pa·s, conductivity 2.7~3.2S / cm. As shown in Table 2 below.

[0067] The method for using the slag system comprises the following steps:

[0068] Step 1: using industrial pure CaF2, CaO, Al2O3, MgO, ZrO2, TiO2 and B2O3 to prepare a slag system according to mass percentage;

[0069] Step 2: pre-melting the prepared slag system in a heating furnace, raising the furnace temperature to 1500° C. and maintaining it for 30 minutes, controlling the target composition of the pre-melted slag within the specified composition range of the present invention, cooling to 30° C. and crushing it in a crusher to a particle size of ≤0.3 cm, and sealing and storing it at 10 kg / bag;

[0070] Step 3: The slag system obtained in step 2 is used for smelting of C-HRA-3 alloy.

[0071] Specifically, in the above step 3, a 5t argon atmosphere protected electroslag furnace may be used for smelting, and the smelting process includes:

[0072] Step 301: 2.5t of smelting electrode rods are loaded into the electroslag furnace crystallizer, the electrode composition meets the composition requirements of C-HRA-3 heat-resistant alloy (where Al, Ti, and B are controlled according to the middle and upper limits of C-HRA-3, and Mg and S are controlled according to the middle and lower limits of C-HRA-3), the surface of the electrode rods is polished and peeled, and the surface is glossy and has no oxide layer, and is ready for use; the water, electricity, and gas systems of the electroslag furnace are checked and tested, and are ready for use;

[0073] Step 302: Before using the electroslag smelting, unseal the sealed slag and pour it into the slag mixing hopper, add 100-150g of aluminum particles, stir and mix evenly, and set aside;

[0074] Step 303: After the arc of the electroslag furnace is started, the slag mixed with aluminum particles is added into the electroslag furnace crystallizer for electroslag smelting.

[0075] Specifically, in the above step 303, about 10 minutes after the arc is ignited, the slag mixed with aluminum particles is slowly added to the electroslag furnace crystallizer, and the amount of slag added within 30 minutes does not exceed 40 kg. After the metal molten pool and the slag pool are initially established, the remaining slag is added within 3 hours.

[0076] Specifically, in the above step 303, during the smelting process, the timer starts from one hour after the electroslag furnace is powered on, and 100 g of aluminum particles are added to the slag of the electroslag crystallizer every 30 minutes until the smelting is completed.

[0077] Specifically, in the above step 3, the design range of the main key process parameters is: electrode diameter is about 375mm, mold diameter is about 435mm, slag layer design is about 150mm, the arc-starting bottom plate thickness of the electroslag furnace crystallizer should reach more than 2.2cm, the power input in the arc-starting stage is about 1400kW, the power input in the steady-state stage is 700~740kW, and the average melting rate is about 4.4kg / min.

[0078] Specifically, the smelting effect of step 3 is as follows: the ingot height after smelting is about 1.7m, the actual ingot weight is about 1.9 tons, the elements are evenly distributed along the length of the ingot and meet the control standard, the surface quality is good, the slag thickness is evenly distributed, and the average slag thickness in the middle of the ingot is ≤1.3mm.

[0079] Table 1 Some components of power-saving desulfurization slag system

[0080]

[0081]

[0082] Table 2 Basic physical properties of power-saving desulfurization slag system

[0083] project 1# 2# 3# 4# 5# 6# 7# Melting point, °C 1360 1358 1362 1361 1366 1358 1364 Viscosity (1700℃), Pa·s 0.015 0.014 0.016 0.016 0.015 0.013 0.013 <![CDATA[Density (1700 °C), g / cm 3 > 2.62 2.61 2.61 2.62 2.6 2.6 2.59 Conductivity (1700℃), S / cm 3.1 3.08 3.11 3.09 3.12 3.1 3.13 Slag skin thickness, mm 0.9 0.8 1 1.1 0.8 0.7 0.9 Slag layer thickness, mm 150 150 150 150 150 150 150 Arc starting power, kW 1400 1450 1370 1350 1440 1470 1440

[0084] After smelting in this embodiment, samples were taken from the ingot head and the ingot tail for chemical detection of element contents, as shown in Table 3 below. As can be seen from Table 3, the components of the steel ingot prepared in the embodiment of the present invention are uniform, for example, the Al content of the ingot head and the ingot tail differs by less than 0.08wt% (for example, 0.05wt% to 0.08wt%); the Ti content of the ingot head and the ingot tail differs by less than 0.04wt% (for example, 0.02wt% to 0.04wt%); the Zr content of the ingot head and the ingot tail differs by less than 0.002wt% (for example, 0.0005wt% to 0.002wt%); the Mg content of the ingot head and the ingot tail differs by less than 0.00001wt% (for example, a difference of 0); the B content of the ingot head and the ingot tail differs by less than 0.0004wt%; the S content of the ingot head and the ingot tail both reaches less than 0.0006wt%, and the desulfurization effect is good.

[0085] Table 3 Ingot head and tail sampling test results / wt%

[0086] project 1# 2# 3# 4# 5# Ingot Al 1.02 1.03 1.03 1.04 1.04 Ingot head Ti 0.41 0.41 0.4 0.41 0.42 Ingot head Zr 0.03 0.028 0.027 0.028 0.026 Ingot head Mg 0.005 0.005 0.005 0.005 0.005 Spindle B 0.0047 0.0046 0.0046 0.0046 0.0046 Spindle head S 0.0006 0.0005 0.0005 0.0005 0.0005 Ingot tail Al 1.08 1.09 1.11 1.11 1.09 Ingot tail Ti 0.45 0.43 0.43 0.44 0.44 Ingot tail Zr 0.032 0.0285 0.028 0.029 0.027 Ingot tail Mg 0.005 0.005 0.005 0.005 0.005 Ingot tail B 0.0043 0.005 0.005 0.005 0.005 Ingot tail S 0.0005 0.0005 0.0005 0.0005 0.0005

[0087] The comparison of the power saving effect between this embodiment and the high-fluorine slag system is shown in Table 4 below. The slag system of the present invention can achieve a production effect of saving 7% to 9% of electric energy and improving production efficiency by 5% to 15%.

[0088] Table 4 Comparison of power saving effect

[0089] Slag type Power consumption (kwh / t) <![CDATA[60% to 70% CaF2 high-fluoride slag]]> 1450～1470 Original slag system 1360～1380 The beneficial effects of saving electricity Save 7% to 9% Production efficiency Increase by 5% to 15%

[0090] The desulfurization effect comparison between this embodiment and the high-fluorine slag system is shown in Table 5 below.

[0091] Table 5 Desulfurization effect comparison

[0092] Slag type Average sulfur content of ingot head and ingot tail (wt%) <![CDATA[60% - 70% CaF2 high-fluoride slag]]> 0.00065 Original slag system 0.00055

[0093] Comparative Example 1

[0094] This comparative example provides a desulfurization slag system for electroslag remelting of C-HRA-3 alloy. The mass percentage of each component in the desulfurization slag system is: CaF2: 41.6%, Al2O3: 20.1%, CaO: 30.3%, MgO: 7%, ZrO2: 0.25%, TiO2: 0.3%, SiO2≤0.3%, and the rest are impurities.

[0095] The method of using the slag in this comparative example is the same as that in Example 1 and will not be repeated herein.

[0096] After smelting, samples were taken from the ingot head and ingot tail for chemical detection of element contents, as shown in Table 6. The difference in Al content between the ingot head and ingot tail of this comparative example reached 0.1wt%, the difference in Ti content between the ingot head and ingot tail was 0.05wt%, and the difference in Zr content between the ingot head and ingot tail was 0.005wt%. The composition uniformity of this comparative example was worse than that of the embodiment.

[0097] Table 6 Ingot head and tail sampling test results / wt%

[0098] Ingot content Ingot tail content Al 1.02 Al 1.12 Ti 0.41 Ti 0.46 Zr 0.03 Zr 0.035 Mg 0.005 Mg 0.005 B 0.0046 B 0.0044 S 0.0005 S 0.0004

[0099] The comparison of the electroslag smelting start-up time and the ingot tail surface quality of Example 1 and Comparative Example 1 is shown in Table 7 below. It can be seen that when the slag system of the present invention is used for electroslag remelting C-HRA-3 alloy, it has a better and faster start-up effect when powered on, and the surface quality of the smelted steel ingot is good.

[0100] Table 7 Comparison of electroslag smelting start-up time and ingot tail surface quality

[0101]

[0102] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy, characterized in that: The mass percentage of each component in the power-saving desulfurization slag system is: CaF2: 49.5%~49.9%, Al2O3: 25.1%~25.9%, CaO: 19.1%~19.9%, MgO: 3.4%~3.7%, ZrO2: 0.46%~0.49%, TiO2: 0.46%~0.49%, B2O3: 0.01%~0.03%, SiO2<0.5%, and the rest are impurities.

2. The power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy according to claim 1, characterized in that: In the power-saving desulfurization slag system, the ratio of the content of Al2O3 to the minimum content of 0.8% of the component Al in the C-HRA-3 alloy is 31.875-32.

375.

3. The power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy according to claim 1, characterized in that: In the power-saving desulfurization slag system, the ratio of the content of ZrO2 to the minimum content of 0.03% of the component Zr in the C-HRA-3 alloy is 15.667-16.

333.

4. The power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy according to claim 1, characterized in that: In the power-saving desulfurization slag system, the ratio of the content of B2O3 to the minimum content of component B in the C-HRA-3 alloy of 0.002% is 5-6.

5. The power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy according to claim 1, characterized in that: In the power-saving desulfurization slag system, the ratio of the content of MgO to the minimum content of 0.005% of the component Mg in the C-HRA-3 alloy is 684-740.

6. The power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy according to claim 1, characterized in that: In the power-saving desulfurization slag system, the ratio of the CaO content to the maximum value of 0.002% required for the component S in the C-HRA-3 alloy is 9800-9950.

7. The power-saving desulfurization slag system for electroslag remelting C-HRA-3 alloy according to claim 1, characterized in that: The melting point of the energy-saving desulfurization slag system is 1290-1400°C; at 1700-1800°C, the density is 2.58-2.63 g / cm 3 , viscosity 0.01~0.02Pa·s, conductivity 2.7~3.3 S / cm.

8. A method for using the power-saving desulfurization slag system according to any one of claims 1 to 7 for electroslag remelting C-HRA-3 alloy, characterized in that: The steps include: Step 1: using industrial pure CaF2, CaO, Al2O3, MgO, ZrO2, TiO2 and B2O3 to prepare a slag system according to mass percentage; Step 2: pre-melting the prepared slag system, and then cooling the pre-melted slag, breaking it, and sealing it for storage; Step 3: The slag system obtained in step 2 is used for smelting of C-HRA-3 alloy.

9. The method of use according to claim 8, characterized in that: In step 3, an electroslag furnace with an inert gas atmosphere protection function is used for smelting, and the smelting process includes: Step 301: Loading smelting electrode rods into the electroslag furnace crystallizer, the electrode composition meets the composition requirements of C-HRA-3 heat-resistant alloy; checking and testing the water, electricity and gas systems of the electroslag furnace equipment, and preparing them for use; Step 302: Before using the electroslag smelting, pour the slag into a slag mixing hopper, add aluminum particles, stir and mix evenly, and set aside; Step 303: After the arc of the electroslag furnace is started, the slag mixed with aluminum particles is added into the electroslag furnace crystallizer for electroslag smelting.

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