Method and device for separating different types of Ti-containing oxides in melt through electromagnetic induction force

Abstract

The invention belongs to the technical field of iron and steel smelting, and discloses a method for separating different types of Ti-containing oxides in a melt through electromagnetic induction force, which comprises the following steps: putting iron with the purity of more than 99% into a crucible, putting the crucible into an induction furnace, introducing inert gas into the furnace body, and heating the iron by controlling the output power of the induction furnace to melt the iron to obtain the melt; after the melt is subjected to heat preservation, aluminum with the purity larger than 99% is added firstly, and titanium with the purity larger than 99% is added for alloying after a period of time; and cooling the alloy furnace or water-quenching to a solidification temperature to obtain a cast ingot. A corresponding apparatus is also provided. By adopting the method and the device, different types of Ti-containing oxides in the melt can be effectively separated.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a method and a device for separating different types of Ti-containing oxides in a melt by electromagnetic induction force. Background Art

[0002] Non-metallic inclusions in steel are a general term for various non-metallic particles carried in steel, and their types can be analyzed from different angles. For example, they can be divided into oxides, sulfides and nitrides according to chemical composition; they can be divided into plastic inclusions, brittle inclusions and non-deformed inclusions according to the plasticity of the inclusions; they can be divided into large inclusions and micro inclusions according to size. In steel, oxides are the most common inclusions, including simple oxides, silicates, spinel inclusions and calcium aluminates. The cause of oxides is the reaction of deoxidizers (such as aluminum and silicon) added during steelmaking with oxygen in molten steel. The most important sulfide inclusion is MnS, which is usually formed due to the segregation of sulfur when the molten steel solidifies. Nitride inclusions such as AlN, TiN, Ti(CN), etc., have high melting points and stability, and exist in steel as precipitation phases. These inclusions have a significant effect on the strength and toughness of steel. There are many sources of inclusions in steel, such as products generated by chemical reactions between various internal material components or by contact between steel and the atmosphere and container in the furnace during the smelting, casting and condensation of steel, or particulate matter precipitated due to factors such as reduced solubility in molten steel when the condensation temperature drops.

[0003] Traditional electromagnetic stirring technology can introduce electromagnetic force into molten steel by applying a strong magnetic field to the induction furnace. The electromagnetic force causes inclusions in the molten steel to migrate to the outside of the melt, promotes the removal of inclusions in the steel and refines the solidification structure of the steel. This technology has the advantages of simple operation and significant effect. However, this technology uses electromagnetic induction force to indiscriminately remove all types of inclusions in molten steel. The purpose is to focus on the interaction between the melt and particles, ignoring the influence of the differences in the particles themselves on their migration behavior in the melt.

[0004] It is generally believed that inclusions larger than 1um are harmful to steel quality because large inclusions destroy the continuity of the steel matrix. In recent years, the "oxide metallurgy" method of using inclusions smaller than 1um to refine the steel structure has been applied. Scholars have found that small and dispersed inclusions in steel can induce the formation of acicular ferrite. Since acicular ferrite is a microstructure with high dislocation density, it can improve the toughness of steel in the heat-affected zone. Among the inclusions with inductive ability, Ti-containing oxides were studied first and widely used in oxide metallurgy.

[0005] In the Fe-Al-Ti-O system, Ti-containing oxides have various valence states, and oxides of Ti with different valence states such as Ti2O3, Ti3O5, and Al2TiO5 can be generated in molten steel at 1600°C. The traditional method uses a resistance heating furnace to melt the alloy, and different types of Ti-containing oxides are mixed together in the solidified ingot, making it difficult to separate different types of Ti-containing oxides and multi-phase inclusions in the melt, and it is impossible to conduct a detailed analysis of the number, density, size, composition, phase and other characteristics of the inclusions, and thus it is impossible to explain the formation mechanism of a single type of Ti-containing oxide in the melt. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a method and device for effectively separating different types of Ti-containing oxides in a melt by electromagnetic induction force.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0008] A method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force, comprising:

[0009] Put iron with a purity greater than 99% into a crucible, place it in an induction furnace, introduce inert gas into the furnace, and heat the iron to melt by controlling the output power of the induction furnace to obtain a melt;

[0010] After the melt is kept warm for a certain period of time, aluminum with a purity greater than 99% is first added, and after a period of time, titanium with a purity greater than 99% is added for alloying;

[0011] The alloy melt is furnace cooled or water quenched to the solidification temperature to obtain an ingot.

[0012] In one embodiment, the method further includes cutting the ingot, grinding and polishing the longitudinal section thereof, first using an optical microscope to obtain the location and characteristic morphology of inclusions in the ingot sample, and then using a scanning electron microscope-energy spectrum to characterize the composition, morphology and size of each oxide.

[0013] In one embodiment, the electromagnetic frequency of the induction furnace is 30-200 kHz, and the maximum output power is 5 kW.

[0014] In one embodiment, the inert gas is argon, helium or nitrogen or a combination thereof.

[0015] In one embodiment, the melt holding temperature is 1600°C, and the temperature deviation is controlled within 3°C.

[0016] In one embodiment, the melt holding time is 5 min to 60 min.

[0017] In one embodiment, the interval between adding aluminum and titanium is 0.5 min to 10 min.

[0018] In one embodiment, the water quenching cooling is: immersing a crucible containing the alloy melt in water for quenching to obtain an ingot, and the water quenching cooling rate is 2°C / s to 8°C / s.

[0019] In one embodiment, the iron having a purity greater than 99% is a mixture of electrolytic iron and an iron-containing alloy.

[0020] Based on a general inventive concept, the present invention also provides a device for the above method of separating different types of Ti-containing oxides in a melt by electromagnetic induction force, comprising:

[0021] A furnace body, including a quartz tube, the top and bottom of which are equipped with quick-change furnace covers;

[0022] An induction coil is arranged outside the quartz tube;

[0023] An air inlet is provided at the bottom of the quartz tube, an air outlet is provided at the top, and a material delivery port is also provided at the top of the quartz tube;

[0024] A refractory lining for supporting the crucible is provided at the bottom of the quartz tube;

[0025] The thermometer uses infrared sensing to detect the temperature of the melt in the quartz tube.

[0026] Compared with the prior art, the beneficial effect of the present invention is that Ti can generate different types of oxides in steel, and the traditional method cannot separate different types of Ti-containing oxides, such as Ti2O3 and Al2TiO5. In this patent application, electromagnetic induction force is used to separate different types of Ti-containing oxides in steel, thereby realizing the study of the generation mechanism of a single type of Ti-containing oxide.

[0027] A magnetic field is applied to the molten steel through an induction furnace. In the Fe-Al-Ti-O system, Al- or Ti-containing oxides migrate to the vicinity of the crucible wall under the action of electromagnetic induction force. Due to the differences in density, size, composition, etc. of different types of Ti-containing oxides in the melt, there are differences in the interfacial tension between different types of Ti-containing oxides in the melt and the molten steel, resulting in different migration rates of different types of Ti-containing oxides, resulting in a "migration time difference", that is, the positions at which they arrive at the crucible wall are different at the same time. Furthermore, the migration behavior of Ti-containing oxides is affected by factors such as current frequency, insulation time, and feed ratio. Therefore, by controlling the above-mentioned influencing factors, different types of Ti-containing oxides in the melt arrive at different positions on the crucible wall at the same time, thereby achieving separation.

[0028] Characterization means show that in the alloy obtained by the method of this patent application, from the cross-section, the outer layer is the area with a thickness of 100 to 700 μm from the crucible wall, and its inclusions are mainly Al2O3, Al+Ti oxide and Al-Ti oxide. The inner layer is the area outside the outer layer of the alloy, and its inclusions are TiN. In the outer layer, Al2O3, Al+Ti oxide and Al-Ti oxide are distributed in different areas, which shows that different types of Ti-containing oxides have achieved effective separation, which is conducive to revealing the generation mechanism of a single type of Ti-containing oxide in the melt. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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 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.

[0030] Figure 1 An apparatus for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to one embodiment;

[0031] Figure 2 1 is a distribution diagram of Al+Ti oxide and Al-Ti oxide in a molten iron-based alloy with and without electromagnetic induction force according to an embodiment, wherein a is a distribution diagram of Al+Ti oxide and Al-Ti oxide in a molten iron-based alloy with and without electromagnetic induction force; b is a distribution diagram of Al+Ti oxide and Al-Ti oxide in a molten iron-based alloy without and without electromagnetic induction force;

[0032] Figure 3 is a distribution diagram of inclusions on a cross section of an alloy according to an embodiment;

[0033] Figure 4 A dispersed and regularly arranged Al-Ti oxide according to an embodiment;

[0034] Figure 5 is an energy spectrum analysis diagram of Al-Ti oxide in an alloy sample according to an embodiment;

[0035] Figure 6 FIG. 4 is an energy spectrum analysis diagram of Al+Ti oxides in an alloy sample according to an embodiment. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0037] See also Figure 1-Figure 6 , a method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force, comprising:

[0038] S110, putting iron with a purity greater than 99% into a crucible, placing it in an induction furnace, introducing an inert gas into the furnace body, and heating and melting it by controlling the output power of the induction furnace to obtain a melt.

[0039] Specifically, in one embodiment, the electromagnetic frequency of the induction furnace is 30kHz to 200kHz, and the maximum output power is 5kW.

[0040] The inert gas is argon, helium or nitrogen or a combination thereof. Preferably, the inert gas is argon.

[0041] S120, after keeping the melt warm, first add aluminum with a purity greater than 99%, and after a certain period of time, add titanium with a purity greater than 99% for alloying.

[0042] Specifically, in one embodiment, the melt is kept at 1600°C, and the temperature deviation is controlled within 3°C. Furthermore, a dual-wave temperature meter is used to monitor the melt temperature, and the temperature deviation is controlled within 3°C by adjusting the output power of the induction furnace. The melt is kept at 5min to 60min, and the interval between adding aluminum and titanium is 0.5min to 10min.

[0043] The dual-wave thermometer is used to monitor the melt for non-contact temperature measurement and provide real-time temperature feedback, which can achieve precise control of temperature, including holding temperature, holding time, heating and cooling rates, etc.

[0044] Specifically, in one embodiment, the iron with a purity greater than 99% is a mixture of electrolytic iron and an iron-containing alloy, and the purity of electrolytic iron, aluminum and titanium are all greater than or equal to 99%, preferably 99.9%. More preferably, the purity of electrolytic iron is greater than 99.9%.

[0045] S130, furnace cooling or water quenching the alloy to a solidification temperature to obtain an ingot.

[0046] Specifically, in one embodiment, cooling the alloy to the solidification temperature to obtain an ingot may include furnace cooling or water quenching. Furthermore, if furnace cooling is adopted, the alloy is directly furnace cooled to the solidification temperature to obtain an ingot, and then the ingot is taken out together with the crucible.

[0047] Or, further, the water quenching cooling method includes: immersing the crucible containing the alloy melt in water to quench to obtain an ingot, and the water quenching cooling rate is 2°C / s to 8°C / s.

[0048] Furthermore, the method of the present patent application for separating different types of Ti-containing oxides in the melt by electromagnetic induction force also includes the steps of:

[0049] S140 also includes cutting the ingot, grinding and polishing its longitudinal section, first using an optical microscope to obtain the existence position and characteristic morphology of inclusions in the ingot sample, then using a scanning electron microscope to characterize the composition and morphology of each inclusion, and finally using energy spectrum analysis to obtain the composition, morphology and particle size distribution of different types of Ti-containing oxides.

[0050] See also Figure 1 The present invention also provides a device applied in the above method, comprising:

[0051] Furnace body 10, induction coil 20, temperature measuring instrument 30. The induction coil 20 is arranged outside the furnace body 10, and the electromagnetic frequency and output power of the induction coil 20 are controlled by the control system.

[0052] The furnace body 10 includes a quartz tube 110, the top and bottom of the quartz tube 110 are equipped with a quick-change furnace cover 120, the bottom of the quartz tube 110 is provided with an air inlet 130, and the top is provided with an air outlet 140, the air inlet 130 is used to introduce inert gas, and the air outlet 140 is used to discharge inert gas. The top of the quartz tube 110 is also provided with a material delivery port 150 for delivering aluminum and titanium, etc. A refractory furnace lining 160 for supporting a crucible is provided at the bottom of the quartz tube 110.

[0053] The thermometer 30 detects the temperature of the melt in the quartz tube by infrared induction, and adjusts the electromagnetic frequency and output power of the induction coil 20 according to the temperature result detected by the thermometer 30 .

[0054] Specifically, the thermometer 30 is a dual-wave thermometer, which performs non-contact temperature measurement on the melt and provides real-time temperature feedback, so that the heating system can achieve precise temperature control, including insulation temperature, insulation time, heating and cooling rates, etc.

[0055] The quick-change furnace cover 120 is used to ensure the airtightness of the furnace body on the one hand; on the other hand, the crucible can be quickly taken out and subjected to the subsequent water quenching process.

[0056] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0057] Unless otherwise specified, various raw materials, reagents, instruments and devices used in the present invention can be purchased from the market or prepared by existing methods.

[0058] Example:

[0059] A method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force comprises the following steps:

[0060] (1) Weigh 120 g of electrolytic iron and place it in a magnesium oxide crucible. Place the crucible in an induction furnace. Control the electromagnetic frequency of the induction furnace to 200 kHz and the maximum output power to 5 kW. Heat the electrolytic iron to melt in an Ar atmosphere at 1600°C until a melt is obtained. During the heating process, the temperature is monitored by a dual-wave thermometer, and the temperature deviation is controlled within 3°C by adjusting the output power of the induction furnace.

[0061] (2) After the melt was kept warm for 30 minutes, 0.1491 g of aluminum (purity: 99.9%) and 0.0954 g of titanium (purity: 99.9%) were added successively at an interval of 2 minutes for alloying.

[0062] (3) Cool the alloy furnace to the solidification temperature to obtain an ingot.

[0063] (4) The total O content of the alloy was determined to be 0.0020% by inert gas melting pulse infrared absorption spectroscopy, the total N content was determined to be 0.0032% by inert gas melting thermal conductivity method, and the soluble Al content was determined to be 0.0497% and the Ti content was determined to be 0.0636% by ICP-OES method.

[0064] Embodiment 2:

[0065] Weigh 100g of electrolytic iron and 20g of carbon-containing pig iron into a magnesium oxide crucible, put the crucible into an induction furnace, control the electromagnetic frequency of the induction furnace to 100kHz, and the maximum output power to 5kW. Heat the electrolytic iron to melt in a N2 atmosphere at 1600℃ until a melt is obtained. During the heating process, the temperature is monitored by a dual-wave thermometer, and the temperature deviation is controlled within 3℃ by adjusting the output power of the induction furnace.

[0066] (2) After the melt was kept warm for 40 minutes, 0.0369 g of aluminum (purity: 99.9%) and 0.0879 g of titanium (purity: 99.9%) were added successively at an interval of 5 minutes for alloying.

[0067] (3) The crucible containing the alloy melt is taken out and immersed in water to quench to obtain an ingot. The water quenching cooling rate is 3.7°C / s.

[0068] (4) The total O content of the alloy was determined to be 0.0069% by inert gas melting pulse infrared absorption spectroscopy, the total N content was determined to be 0.0110% by inert gas melting thermal conductivity method, and the soluble Al content was determined to be 0.0123% and the Ti content was determined to be 0.0586% by ICP-OES method.

[0069] Characterization analysis:

[0070] Characterization and analysis of the alloys obtained in Examples 1 and 2 revealed that the inclusion observation area on each alloy cross section includes two regions: an outer layer and an inner layer. The distribution of inclusions on the alloy cross section is shown in Figure 2. Figure 3 shown.

[0071] The outer layer refers to the area with a thickness of 100 to 700μm from the crucible wall. The outer layer inclusions are mainly Al2O3, Al+Ti oxide and Al-Ti oxide. The inner layer is the area outside the outer layer, and its inclusions are TiN. Al2O3 is a deoxidation product after the addition of Al. Its formation mechanism is that the Al2O3 generated in the molten steel migrates from the melt to the crucible wall and agglomerates into clusters under the action of electromagnetic induction force. Al+Ti oxide and Al-Ti oxide are both distributed in the outer layer. Al+Ti oxide refers to a heterogeneous phase with uneven distribution of Al and Ti elements. Al-Ti oxide refers to a homogeneous phase with uniform distribution of Al and Ti elements. Such as Figure 3 As shown, in the outer layer, Al2O3, Al+Ti oxide and Al-Ti oxide are distributed in different areas. It can be seen that by adopting the method of this patent application, different types of Ti-containing oxides are effectively separated, which is conducive to revealing the formation mechanism of a single type of Ti-containing oxide in the melt.

Claims

1. A method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force, characterized in that: include: Put iron with a purity greater than 99% into a crucible, place it in an induction furnace, introduce inert gas into the furnace, and heat the iron to melt by controlling the output power of the induction furnace to obtain a melt; After the melt is kept warm for a certain period of time, aluminum with a purity greater than 99% is first added, and after a period of time, titanium with a purity greater than 99% is added for alloying; The alloy melt is furnace cooled or water quenched to the solidification temperature to obtain an ingot.

2. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The method also includes cutting the ingot, grinding and polishing its longitudinal section, first using an optical microscope to obtain the location and characteristic morphology of inclusions in the ingot sample, and then using a scanning electron microscope-energy spectrum to characterize the composition, morphology and size of each oxide.

3. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The electromagnetic frequency of the induction furnace is 30-200kHz and the maximum output power is 5kW.

4. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The inert gas is argon, helium or nitrogen or a combination thereof.

5. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The melt insulation temperature is 1600℃, and the temperature deviation is controlled within 3℃.

6. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The melt holding time is 5min to 60min.

7. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The interval time for adding aluminum and titanium is 0.5min to 10min.

8. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: The water quenching cooling comprises: immersing a crucible containing the alloy melt in water and quenching to obtain an ingot, and the water quenching cooling rate is 2°C / s to 8°C / s.

9. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that: Iron with a purity greater than 99% is a mixture of electrolytic iron and iron-containing alloys.

10. A device for the method of separating different types of Ti-containing oxides in a melt by electromagnetic induction force as claimed in any one of claims 1 to 9, characterized in that: include: A furnace body, including a quartz tube, the top and bottom of which are equipped with quick-change furnace covers; An induction coil is arranged outside the quartz tube; An air inlet is provided at the bottom of the quartz tube, an air outlet is provided at the top, and a material delivery port is also provided at the top of the quartz tube; A refractory lining for supporting the crucible is provided at the bottom of the quartz tube; The thermometer uses infrared sensing to detect the temperature of the melt in the quartz tube.

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