WO2009149581A1

WO2009149581A1 - Additive for preparing steel containning super-finely dispersed oxide, producing method and application of the same

Info

Publication number: WO2009149581A1
Application number: PCT/CN2008/001133
Authority: WO
Inventors: 唐复平; 王晓峰; 刘万山; 孟劲松; 任子平; 李德刚; 陈本文; 王仁贵; 张军; 王文仲; 李镇; 张晓军; 孙群; 栗红; 常桂华
Original assignee: 鞍钢股份有限公司
Priority date: 2008-06-12
Filing date: 2008-06-12
Publication date: 2009-12-17

Abstract

This invention provides a secondary refining technique for steelmaking, particular an additive for preparing steel containing super-finely dispersed oxide, producing method and application of the same, which belongs to metallurgy technical field. The said additive is a composite sphere composed of core and shell. The said shell is composed mainly of calcium oxide and/or magnesium oxide. One kind of core contains mainly beneficial oxides and expanding agents, or the other kind is composed of pre-melt dreg powder agent(s) having low melting point and expanding agent(s). It can allow oxides type impurities more finely and dispersing diffusively in steel, moreover there is many formulations and of great advantage to application, through charging in LF, RH, VD or CAS-OB by applying wire-feeding, powder spraying, pellet jetting and even feed directly means. The steel containing super-finely dispersed oxide whose diameter less than 1 μm can be produced stably and rapidly, so as to greatly improve the quality of steel and lower the cost of refining.

Description

Additive for preparing fine oxide dispersed steel, and preparation method and application thereof

The invention relates to an off-furnace refining technology for steel making, in particular to an additive for preparing fine oxide dispersed steel, a preparation method and application thereof, and belongs to the technical field of metallurgy.

Background technique

It is well known that the use of beneficial inclusions (CaO, Ti ₂ O ₃ , BN, REM (0, S), VN, TiN, Zr0 _{2 ,} etc.) dispersed in steel can improve the quality of molten steel. In recent years, inclusions having a particle diameter of less than 2 μm, particularly techniques for improving the amount of dispersion in steel by using oxide-based inclusions, are attracting attention. Recently, some patents have disclosed that in order to increase the amount of oxide dispersion, in the case of pre-deoxidation, after adjusting the oxygen content to a certain range, a strong deoxidizer is added, which is a method of using a single deoxidation product.

For example, in the patent JP 2001-288509, after controlling the oxygen in the molten steel to 20 to 80 ppm, Ti, A1 and Ca are sequentially added for deoxidation, which is added in the order of deoxidation ability from weak to strong, and can be refined and Increase the amount of oxide dispersion. This method can reduce the supersaturation of oxygen in the molten steel, and can also repeatedly perform the deoxidation reaction, thereby suppressing the excessive growth and coarsening of the oxide. However, in the method mentioned in the patent literature, the composition of the inclusions is determined by the repeated addition of deoxidizing elements, and the amount of oxide dispersion is determined by the oxygen initially dissolved in the molten steel, and also does not promote the refinement and dispersion of the oxide. . That is to say, these methods do not go beyond the scope of the conventional deoxidation method, nor are they technical means for effectively increasing the amount of dispersion of fine inclusions.

In addition, some patent documents have reported methods for increasing the amount of fine oxide dispersion or controlling the blowing of oxygen into molten steel.

In the patent document JP 8-246026, the method of controlling the form of inclusions in steel is to add oxygen to the molten steel in the sedative state after adding the deoxidizing agent, and the oxygen blowing amount per ton of molten steel is 1 χ 10· ² ～ ⁶ χ 10' ² . However, in this document, the only method of adding oxygen source is adopted. In the patent document JP 10-193046, a method of supplying oxygen is mentioned (using a solid oxygen ion conductor, by applying a voltage, oxygen is added to

1

Confirmation In molten steel), a method of forming and dispersing fine oxides, and a method of blowing an oxidizing gas into molten steel to disperse fine oxides. These methods all supply oxygen under a low oxygen state, and the supersaturation is not high in the deoxidation reaction, and the formation of coarse deoxidation products can be suppressed. However, the method mentioned in this document is inferior in practicability in the steel production process premised on mass production due to the slow oxygen supply rate. The patent document JP2002-256330 mentions that after adding a deoxidizing agent to molten steel, the molten steel having a high oxygen content is finer than the oxide in the molten steel to which the deoxidizing agent is added. However, in this document, it is also mentioned that the molten steel having a high oxygen content is mixed with the molten steel to which the deoxidizer is added, and it is difficult to mass-produce the molten steel by this method. Therefore, in order to improve the quality of molten steel, the problem to be solved is to stably and rapidly increase the dispersion of oxide particles dispersed in steel, and to apply the production method of fine oxide dispersed steel to modern steel production. Summary of the invention

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the prior art, and an object thereof is to provide an additive and a preparation process thereof for preparing a fine oxide dispersion steel.

Another object of the present invention is to make the oxide-based inclusions finely and dispersedly distributed in the steel by the additive of the present invention, thereby improving the quality of the steel, that is, preparing the fine oxide-dispersed steel in the refining process by using the additive of the present invention. Process method.

In order to solve the above technical problems, the present invention is achieved by: an additive for preparing a fine oxide dispersion steel, which is a composite sphere composed of a core and an outer shell, the outer shell mainly being composed of calcium oxide or oxidation One or a mixture of two of magnesium.

The core is prepared from the following raw materials by weight percentage: beneficial oxide 0.1~99% _; expansion agent 1~70% _; binder 0~30%.

The core is prepared by the following raw materials in a weight percentage: beneficial oxide 30~80% _; expansion agent 8~55 % _; binder 5~15%.

The core is prepared from the following raw materials in percentage by weight: low melting pre-slag powder 1%~70%; expansion agent 1°/. ~60%; calcium fluoride 0~40%; binder 0~20%.

The core is prepared from the following raw materials in percentage by weight: low melting point premelted powder 10%~50%; expansion agent 10%~45%; calcium fluoride 5%~30%; binder 5%~15%.

The outer casing also includes 0 to 20% of a binder.

The beneficial oxide is any one of CaO, Ti ₂ O ₃ , ΖιΌ _2, and rare earth oxide. The rare earth oxide is any one of Ce, Nd, La, Gd, and Sm oxides. An additive for preparing fine oxide-dispersed steel, characterized by a powder mainly composed of a low-melting pre-slag powder and a mixture of a swelling agent and one or both of calcium oxide or magnesium oxide.

The additive is prepared from the following raw materials by weight percentage: expansion agent 1~60% _; low melting point premelting slag powder 1~70% _; calcium oxide or magnesium oxide or a mixture of calcium oxide and magnesium oxide 10~98%; Calcium fluoride 0~40%; binder 0~20%.

The additive is prepared from the following raw materials by weight percentage: 10~45% of the expansion agent _; 10~50% _{of the} low melting point premelted slag powder _; 30~70% of the mixture of calcium oxide or magnesium oxide or calcium oxide and magnesium oxide; Calcium fluoride 5~30%; binder 5~15%.

The expansion agent consists of calcium carbonate or magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate.

The additive also includes a cored dosage form.

The low-melting pre-melted slag powder is prepared from the following raw materials by weight: CaO 10~70%, A1 ₂ 0 ₃ 15~50%, SiO ₂ 0~10%, MgO 0~10%, CaF ₂ 0~30% , melting point 1100~1550. (.

The binder is a mixture of any one or more of clay, ordinary cement, bentonite, and water glass.

A method of preparing the additive, comprising the steps of:

1), preparation of the core: (a), mixing: According to the formulation ratio, the raw materials required for the core are crushed and crushed to make the particle size of Inn! ~ 3.5mm, put the above powder and binder into the mixer for thorough mixing and mixing, mixing time is 1 h~3h for use. (b), drying: the above mixed powder is dried in a dryer, the drying temperature is 80 ° C ~ 150 ° C, the time is 2 h ~ 8 h. (c), the core of the ball: The ball after the drying process is passed through a ball making device to make the ball, and the diameter of the core is 0.05 mm~ 2) Preparation of composite spheres and pellets: d) Preparation of shell: The raw materials required for the shell are thoroughly mixed in the mixer according to the ratio. The activity of calcium oxide and magnesium oxide is 200 ml, and the mixing time is 1 h~ 3h standby. (e), compounding: The above-mentioned prepared core and shell material are compositely ball-formed on a ball-making device by a rolling method, and the prepared composite sphere has a size of 20 to 80 mm; the diameter of the prepared composite pellet is controlled at 0.25. ~20mm. (f), overall drying: The composite spheres and pellets prepared in the above steps are dried in a dryer, and the drying temperature is 60 ° C to 200 ° C, and the time is 10 h to 24 h. (g), packaging: after drying, cool to room temperature, bagging, single weight 10 kg ~ 30kg / bag, packaging to ensure good sealing, prevent moisture, and use within 20 days.

A method of preparing the additive, comprising the steps of:

1 Mixing powder: According to the formula ratio, the particle size is Inn! ~ 3.5mm low melting point pre-slag powder, calcium fluoride, calcium carbonate, magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate, calcium oxide, magnesium oxide or a mixture of calcium oxide and magnesium oxide and binder into the mixer Mix well and mix for a mixture of lh~8 h. 2 Drying treatment: The powder prepared above is dried in a drying apparatus at 80 ° C ~ 200 ° C for 2 h ~ 24 h to obtain a finished powder. 3 line: a low carbon steel strip with a thickness of 2mm~5 mm is used as the outer skin of the cored wire, and the finished core powder prepared in step 2 is used on the line making machine, and a single layer steel strip is used to make the core wire. The wire speed is 8~30m/min, and the core powder content is 100~240g/m. 4 Packing: Cool to room temperature, pack the powder into 500~1000kg/bag, pack the core wire into 1000~2000m/roll, ensure the seal is good, prevent moisture, and use within 20 days.

A process for preparing fine oxide dispersed steel, comprising the following steps:

I. Removal of deoxidation product: When the molten steel is deoxidized, the powder of the additive is fed to the molten steel by LF, RH, VD or CAS-OB by feeding, spraying, pelletizing or direct feeding of the sphere. The core wire, the composite sphere, the composite pellet, wherein the core of the composite pellet and the composite sphere is mainly a low-melting pre-slag powder and a swelling agent.

After the additive is added to the molten steel, a decomposition reaction first occurs to produce a large amount of finely dispersed co ₂ gas. The reaction process itself causes a small range of intense flow and agitation of the molten steel around the combined powder. Provides a rise in conditions and opportunities for the rise in oxide inclusions. Further, the generated co ₂ gas causes the polymerization bubbles to rise, and the formation and rise of the small bubbles is agitation in a small range of the molten steel. The formation process of small bubbles is the process of adsorbing inclusions. That is to say, around the small bubbles, numerous oxide inclusions are adsorbed, small bubbles are floated, and the molten steel is floated with oxide inclusions, and is discharged to the slag. in. The carbonate powder fed into the molten steel is finely dispersed, and numerous carbonate powders are decomposed in the molten steel to produce co ₂ and polymerize into small bubbles to float, thus forming numerous small-scale steels in the molten steel. The liquid flows or stirs, and the whole molten steel flows and boils, and the floating of numerous small bubbles makes the removal of oxide inclusions more effective. At the same time, in the different regions or small ranges in the molten steel in which the flow has occurred, the added oxidant lowers the oxygen content of the molten steel and also discharges the generated oxide.

In addition, another product of the decomposition reaction of the additive of the present invention has a small CaO size, can be rapidly melted in the molten steel to form a slag droplet, and forms a low-melting calcium aluminate with the A1 ₂ ₃ inclusion in the molten steel to float into the ladle slag. Thereby removing the A1 ₂ 0 ₃ inclusions produced during the refining process and reducing the total oxygen content in the steel. The speed and efficiency of the overall reaction is controlled by optimized selection of various combinations of powder formulations.

II. Formation of dispersive oxides: When the oxygen content of the molten steel is between 0.0001% and 0.008%, the composite spheres whose core is mainly beneficial oxides and expansion agents are added to the molten steel during the RH refining process, and the amount of the composite spheres is added. It is 0.5~3.5kg/t, the single addition amount is 50~130kg, and the addition speed is 0.1~1.5kg/s.

Since the composite sphere is added during the RH refining process, the beneficial oxides are released after the composite sphere bursts, and are dispersed in the molten steel. Because the beneficial oxidizing substances are fine and have a high melting point, they do not float or melt in the molten steel. , aggregation.

The core wire, the powder, the composite sphere, the composite pellet of the additive are fed to the molten steel at LF, RH, VD or CAS-OB:

(1) The powder is sprayed into the molten steel after the refining of LF, RH, VD or CAS-OB, and the conveying gas is a mixed gas of either or both of Ar and C0 ₂ , and the conveying pressure is controlled at 0.01 to 2.0 MPa, powder The feed rate is 0.3 to 1.5 kg/t at the feed rate and 0.01 to 3.5 kg/s at the feed rate. (2) The composite sphere is added at the end of the RH refining process, and the vacuum of the RH is 66.7 to 500 Pa. The filling position is the discharge pipe on the opposite side of the down pipe, and the cycle is 0 to 15 min after the addition. The feed rate is 0.3 to 1.5 kg/t, and the feed rate is 0.01 to 2.0 kg/s.

(3) The core wire is fed after the end of alloying in the LF, RH, or CAS-OB refining stage, and the argon mixing is stopped during the feeding process. The feeding speed is 180~350m/min, and the feeding amount is 0.3~1.5kg. /t, after the feeding line is still 0.5~10min, and then argon blowing is lightly processed, the flow rate of argon gas is 50~280Nl/min, and the weak argon blowing time is 0.5~5min.

(4) The shot is carried out in the late stage of LF, RH or CAS-OB refining, using argon as the carrier, and the gas pressure is controlled at 0.1 to 1.0 MPa. The injection rate is 0.5 to 5 kg/t, and the feed rate is 0. l~3.0 kg/s.

The advantages and benefits of the present invention are as follows:

(1) Since the invention proves that the formula is scientific and reasonable, and has various dosage forms, it can be added to the molten steel by LF, RH, VD or CAS-OB by means of feeding, dusting, shot blasting or even direct ball-shaped input. The additive of the invention achieves the dispersion of the beneficial oxide in the molten steel, and because the beneficial oxidizing substance has fine spots and high melting point, it does not float or melt and polymerize in the molten steel, thereby impregnating the oxide in the molten steel. Control is more effective and complete.

(2) It is possible to stably and rapidly mass produce fine oxide dispersed steel having an oxide particle size smaller than Ιμιη.

(3) The invention has the advantages of simple process, easy operation, low cost and effective application in the modern large-scale steel production process.

detailed description

The invention is further described in detail below with reference to the specific embodiments, but the scope of the invention is not limited by the specific embodiments. In addition, any changes or modifications that are easily made by those skilled in the art without departing from the scope of the present invention will fall within the scope of the appended claims.

Example 1 An additive for preparing a fine oxide dispersion steel, which is a composite sphere composed of a core and an outer shell, the outer shell being mainly composed of one or a mixture of two or more of calcium oxide or magnesium oxide.

The outer shell of the composite sphere is prepared by mixing 1% of ordinary cement with calcium oxide; the core is 0.1% by weight of Ti ₂ O ₃ ; 70% of calcium carbonate; 29.9% of clay.

According to the above ratio, the solid raw material required for the core is crushed and crushed, and at the same time, the airflow micro-grinding is used to achieve the particle size of lnm~3.5mm, and then the powder is placed in the mixer for thorough mixing and mixing. The mixing time is l~3h. The mixed raw materials are dried in a drying apparatus, and the drying temperature is 80 to 150 ° C, and the time is 2 to 8 hours. The dried raw material is ball-formed on a disc pelletizer by a rolling method. The rotation speed of the disc pelletizer is 400 to 1600 r/min, and the control of the sphere size is determined by screening to obtain a sphere having a diameter of l to 40 mm. According to the above ratio, the powder required for the outer casing is thoroughly mixed in the mixer, the activity of calcium oxide is 200 ml, and the mixing time is l~3 h. The prepared core sphere and the shell material are compositely ball-formed on a disc pelletizer by a rolling method, and the thickness of the shell is 0.1 to 20 mm, and the size of the sphere is controlled by screening, and the prepared composite sphere size is 20 ~80mm can be. The composite sphere prepared in the above step is dried in a drying apparatus, and the drying temperature is 60 to 200 ° C, and the time is 10 to 24 hours. After the composite spheres are dried, they are cooled into ultra-thin high-strength polyethylene plastic bags. Each bag has a single weight of 10~30kg/bag. The package should be well sealed, protected from moisture and used within 20 days.

An additive for preparing fine oxide dispersion steel characterized by a powder and a core wire mainly composed of a low melting point pre-slag powder and a mixture of a swelling agent and one or both of calcium oxide or magnesium oxide.

Preparation of low-melting pre-melting slag, according to formula ratio, take CaO powder 40%, A1 ₂ 0 ₃ powder 35%, Si0 ₂ powder 10%, MgO powder 10%, CaF ₂ powder 5% into the mixer for uniformity The mixture is then melted in a magnesite, cooled and ground to a powder having a particle size of 1 nm to 3.5 mm, and the melting point thereof is set at 1100 to 1550 ° C; and the particle size is 1 nm to 3.5 according to the formulation ratio. Mm low melting pre-slag powder 30 %, calcium fluoride powder 5%, calcium oxide powder 55%, calcium carbonate 5%, clay 5% into the mixer for uniform mixing l~8h, wherein the calcium oxide activity 200! 111 _; preparation The good powder is put into the drying equipment at 80~200°C for drying for 8~24 h; the low carbon steel strip with the thickness of 2~5 mm is used as the outer skin of the core wire, and the core is baked. The above-mentioned powder is dried on a line-making machine, and a single-layer steel belt is used to form a core wire, the wire speed is 8 to 30 m/min, and the core powder content is 100 to 240 g/m. The core wire is packed into 1000~2000m/roll, and the package should be well sealed, protected from moisture, and used within 20 days.

A process for preparing fine oxide dispersion steel, comprising the steps of:

After the alloying at the end of the LF refining, the core wire is fed, and the argon stirring is stopped during the feeding process. The feeding speed is 180-350 m/min, and the feeding amount is 0.3-1.5 kg t. After feeding the wire, it is still 0.5~10min, and then argon gas is treated. The flow rate of argon gas is 50~280Nl/min, and the weak argon blowing time is 0.5~5min. After the argon blowing, the ladle is moved to the RH station. When sampling and analyzing the oxygen content of the molten steel at 0.0001 ~ 0.008%, the composite sphere with the core mainly beneficial oxide and expansion agent is added into the molten steel during the RH refining process, and the position is the discharge pipe on the opposite side of the down pipe. The addition amount is 0.5~3.5kg/t, and the composite sphere is transferred and poured out immediately after being added for 1~5min, and the continuous casting adopts full-scale protection pouring.

Example 2

The outer shell of the composite sphere is prepared by mixing 20% clay with a mixture of calcium oxide and magnesium oxide; the core is Ca055% by weight; calcium carbonate 44%; bentonite 1%.

According to the above ratio, the solid raw material required for the core is crushed and crushed, and at the same time, the airflow micro-grinding is used to achieve the particle size of ΙΟηπ! ~ 2.5mm, then put the above powder into the mixer for thorough mixing and mixing, the mixing time is l~2h. The mixed raw materials are dried in a drying apparatus, and the drying temperature is 80 to 120 ° C, and the time is 2 to 5 hours. The raw material after the drying treatment is formed into a ball on a disc pelletizer by a rolling method, and the rotation speed of the disc pelletizer is 400 to 1600 r/min, and the control of the sphere size is determined by screening, and the diameter of the sphere is obtained as l~ 40mm. The powder required for taking the outer casing according to the above ratio is thoroughly mixed in the mixer, the activity of calcium oxide is 200 ml, and the mixing time is 1~ 3h. The prepared core sphere and the shell material are compositely ball-formed on a disc pelletizer by a rolling method, and the thickness of the shell is 0.1-20 mm. The size of the sphere is controlled by screening, and the prepared composite sphere size is 20 ~80mm can be. Others are the same as in Example 1, and are not described.

Take CaO10°/ according to the formula ratio. , Al ₂ O ₃ 50% Si〇 ₂ 5%, MgO 5%, CaF ₂ 30% Preparation of low melting point premelted slag powder method is the same as in Example 1; taking prepared low melting point premelted slag powder 1%, calcium fluoride 30%, magnesium carbonate 40 ° /. , magnesium oxide 29%. The powder preparation process and the drying process are the same as those in the first embodiment; the low carbon steel strip having a thickness of 2 to 5 mm is used as the sheath of the core wire, and the core is the dried composite powder on the line machine, and is packaged. The single-layer steel belt lap type core wire is used, the wire wrapping speed is 8~30m/min, and the core wire powder content is 100~240g/m. The core wire is packed into 1000~2000m/roll, which is convenient for direct control of the addition amount and the joining speed. The cross section of the core wire is round, and the package should ensure good sealing, prevent moisture, and be used within 20 days.

A process for preparing fine oxide dispersion steel, comprising the steps of:

After the molten steel is deoxidized and alloyed, the ladle is transported to the RH station, and the core wire is fed in the late stage of RH refining, and the feeding line position is selected on the side of the RH down pipe. The feeding speed is 180~350m/min, and the feeding amount is 0.5~4.5kg/t. The static time after feeding the line is 3~10min. When the oxygen content of the molten steel is 0.0001 0.008%, the composite sphere with the core mainly beneficial oxide and expansion agent is added to the molten steel during the RH refining process, and the addition position is decreased. At the opposite side of the pipe, the amount of the pipe is 0.5~3.5kg t. After the compound ball is added, the pipe is moved out for 0~3min, and the casting is carried out by continuous casting.

Example 3

The outer shell of the composite sphere is prepared by mixing 15% clay with a mixture of calcium oxide and magnesium oxide; the core is taken as Zr0 ₂ 99% by weight _; magnesium carbonate 1%.

According to the above ratio, the solid raw material required for the core is crushed and crushed, and at the same time, the airflow is micromilled and ground to a particle size of 50 nm to 2.5 mm, and the powder is placed in a mixer for thorough stirring and mixing. The mixing time is l~3h. The mixed raw materials are dried in a drying apparatus, and the drying temperature is 90 to 130 ° C, and the time is 2 to 5 h. The raw material after the above drying treatment is extruded The method is to make a ball on a ball press, and the control of the size of the sphere is determined by sieving, and the diameter of the sphere is l~40 mm. The powder required for taking the outer casing according to the above ratio is thoroughly mixed in the mixer, the activity of calcium oxide and magnesium oxide is 200 ml, and the mixing time is l~3 h. The prepared core sphere and the shell material are compositely ball-formed on a disc granulator by a rolling method, and the thickness of the shell is 0.1-20 mm, and the size of the sphere is controlled by screening, and the prepared composite sphere size is 20 ~80mm can be. Others are the same as in Example 1, and are not described again.

The method for preparing the low-melting pre-melted slag powder according to the formula ratio of CaO70%, Al ₂ 0 ₃ 15%, Si0 ₂ 3%, MgO 2%, and CaF ₂ 10% is the same as in the first embodiment; Slag powder 45% mixture of calcium carbonate and magnesium carbonate 30%, mixture of calcium oxide and magnesium oxide 10%, bentonite 10%, water glass 5% into vertical mixing mixture 2~8 h; The equipment is dried, the drying temperature is 80~200 °C, and the time is 8~24 h. Cool to room temperature and put into ultra-thin high-strength polyethylene plastic bag, moisture-proof sealed package 1000kg / bag, the package should ensure good sealing, prevent moisture, and use within 20 days.

A process for preparing fine oxide dispersion steel, comprising the steps of:

After deoxidation of the molten steel, after the refining of LF, VD or CAS-OB is completed, the above-mentioned finished powder is sprayed into the molten steel, and the conveying gas is a mixed gas of Ar and C0 ₂ , and the conveying pressure is controlled at 0.01 to 2.0 MPa, and the powder is conveyed. The amount is moved out at 0.01~3.5kg/s, and the ladle is transported to the RH station for refining. When the oxygen content of the molten steel is between 0.0001 and 0.008%, the composite sphere with the core of beneficial oxide and expansion agent is added to the molten steel during the RH refining process, and the position is the discharge pipe on the opposite side of the downcomer. The addition amount is 0.5~3.5kg/t, and the casting is carried out immediately after the cycle is 0~5min, and the continuous casting is carried out by the whole process.

Example 4

The outer shell of the composite sphere is prepared by mixing 15% clay with a mixture of calcium oxide and magnesium oxide; the first core is 80% by weight of boron nitride; and 2:1 is taken by calcium carbonate and magnesium carbonate. Mixing 15%, clay 4%, water glass 1%; second core by weight first taking CaO50%, Al ₂ O ₃ 40%, Si0 ₂ 5%, MgO 5% to prepare low melting point premelted slag powder, its preparation The method is the same as in the first embodiment, Preparing 60% of low-melting pre-melted slag powder, 10% of calcium fluoride, 20% of calcium carbonate, and 10% of clay; crushing and crushing the solid raw materials required for the two cores according to the above ratio, The airflow micro-grinding is used to achieve a particle size of 1 nm to 1.5 mm, and then the above two kinds of core powders are respectively placed in a mixer for thorough stirring and mixing, and the mixing time is l~3h. The above separately mixed raw materials are separately dried in a drying device, and the drying temperature is 80 to 110 ° C, and the time is 2 to 6 hours. The two raw materials after the above drying treatment are made into a core on a ball press by an extrusion method, and the control of the size of the core is determined by sieving, and the diameter of the core is 0.05 to 40 mm. The powder required for taking the outer casing according to the above ratio is thoroughly mixed in the mixer, the activity of calcium oxide and magnesium oxide is 200 ml, and the mixing time is l~3 h. The first ball core and the outer shell material are combined and ball-made on a disc pelletizer by a rolling method, and the size of the sphere is controlled by screening, and the prepared composite sphere has a size of 20 to 80 mm; A good second core and shell material are compositely pelletized by a rolling method on a disc granulator, and the size of the pellets is controlled by sieving. The size of the prepared composite pellets is 0.25 to 20 mm, and finally The composite sphere and the composite pellet are dried at 60~120 °C, and the drying time is 10~18h. After cooling to room temperature, they are packed in 10~30kg/bag and used within 20 days.

After the alloying at the end of the LF, RH or CAS-OB refining, the prepared composite pellets are taken for shot peening, and argon gas is used as the carrier, the gas pressure is controlled at 0.1 to 1.0 MPa, and the injection amount is 0.5 to 5 kg/t. , move out, transport the ladle to the RH station for refining. When sampling and analyzing the oxygen content of the molten steel at 0.0001 ~ 0.008%, the composite sphere with the core mainly beneficial oxide and expansion agent is added into the molten steel during the RH refining process, and is added to the discharge pipe at the opposite side of the down pipe. The addition amount is 0.5~3.5kg/t, and the composite sphere is transferred and poured out immediately after being added for 1~5min, and the continuous casting is protected by the whole process.

Example 5

The outer shell of the composite sphere is prepared by mixing 8% of clay with calcium oxide; the core is 65% by weight of boron nitride; 255% of calcium carbonate; 2% of ordinary cement and 8% of bentonite.

The solid raw material required for the above-mentioned core is crushed and crushed according to the above ratio, and the airflow is also adopted. Micro-grinding grinding, reaching a particle size of 90ηπ! ~ 3.5mm, then put the above powder into the mixer for thorough mixing and mixing, the mixing time is l~3h. The mixed raw materials are dried in a drying device, and the drying temperature is 110 to 150 ° C, and the time is 2 to 6 h. The raw material after the drying treatment is made into a ball on a disc pelletizer by a rolling method, and the rotation speed of the disc pelletizer is 400 to 1600 r/min, and the control of the core size is determined by screening, and the diameter of the core is obtained. 10~40mm. The powder required for taking the outer casing according to the above ratio is thoroughly mixed in the mixer, the activity of calcium oxide is 200 ml, and the mixing time is l~3 h. The prepared core sphere and the shell material are compositely ball-formed on a disc pelletizer by a rolling method, and the size of the sphere is controlled by screening, and the prepared composite sphere has a size of 20 to 60 mm. Others are the same as in Example 1, and are not described again.

The method of preparing low-melting pre-melted slag powder is the same as that of the first embodiment according to the formulation ratio of CaO50%, Al ₂ O ₃ 30%, CaF ₂ 20%; taking the prepared low-melting pre-melted slag powder 3%, calcium fluoride 2%, calcium carbonate 10%, magnesium oxide 85% were powdered in the same manner as in Example 1; after drying, a low carbon steel strip having a thickness of 2 mm was used as the sheath of the cored wire, and the core was the dried powder. On the wire making machine, a core wire was prepared in the same manner as in Example 2, and packaged into a 1000 m/roll, which had a square cross section and was used within 20 days.

After the CAS-OB alloying treatment, the core wire is fed, and the argon stirring is stopped during the feeding process, the feeding speed is 200 to 350 m/min, and the feeding amount is 0.5 to 1.5 kg/t. After feeding the line, it is still 0.5~10min, then lightly processed by argon blowing, and then lightly treated by argon blowing. The flow rate of argon gas is 50~280Nl/min, and the argon blowing time is carried out at 0.5~10min. The ladle is transported to the RH station for refining. . When sampling and analyzing the oxygen content of the molten steel at 0.0001 - 0.008%, the composite sphere with the core mainly as a beneficial oxide and expansion agent is added to the molten steel during the RH refining process, and is added to the discharge pipe at the opposite side of the down pipe. The amount of addition is 0.5~3.5kg/t. After the ball is added, it is transferred for 1~4min and then poured out. The continuous casting is fully casted. Example 6

The outer shell of the composite sphere is prepared by mixing 20% clay with magnesium oxide; the first core is 70% by weight of rare earth oxide; 20% of calcium carbonate and magnesium carbonate is taken according to 1:1, clay 7 %, water glass 3%; second core according to the weight percentage first take Ca025%, Al ₂ 0 ₃ 45%, Si0 ₂ 8%, Mg0 8%, CaF ₂ 14% to prepare low melting point premelted slag powder, the preparation method thereof With the same example 1, the prepared low melting point premelted slag powder 2%, calcium fluoride 18%, magnesium carbonate 55%, calcium oxide 15%, bentonite 10;

According to the above ratio, the solid raw materials required for the two kinds of cores are separately crushed and crushed, and at the same time, the airflow micro-grinding is used to achieve the particle size of 80ηπ! ~ 3mm, then put the above two kinds of core powder into the mixer for mixing and mixing, the mixing time is l~3h. The above two separately mixed raw materials are separately dried in a drying apparatus, and the drying temperature is 100 to 140 ° C for 2 to 4 hours. The two raw materials after the above drying treatment are subjected to a pressing method to form a core on a ball press, and the control of the size of the core is determined by sieving, and the diameter of the sphere is 0.05 to 40 mm. The powder required for taking the outer casing according to the above ratio is thoroughly mixed in the mixer. The activity of calcium carbonate and magnesium oxide is 200 ml, and the mixing time is l~3 h. The two kinds of cores and the shell materials which have been prepared are respectively combined and ball-formed on a disc pelletizer by a rolling method, and the size of the sphere is controlled by screening, and the two composite spheres are 20 to 80 mm in size, and finally The two composite spheres were dried at 90~160 °C, dried for 10~15h, cooled to room temperature and packed for 10 kg ~ 30kg/bag, and used within 20 days.

When the molten steel is deoxidized, a composite sphere containing the second core is added at the end of the RH refining treatment, and the vacuum of the RH is 66.7 to 500 Pa. The feeding position is at the discharge pipe on the opposite side of the down pipe, the feeding amount is 0.3~1.5kg/t, and the cycle time after the composite sphere is added is l~15min. When the oxygen content of the molten steel is 0.0001 ~ 0.008%, The composite sphere containing the first core is added to the molten steel during the RH refining process, and is added to the blanking pipe at the opposite side of the downcomer, the amount of addition is 0.5~3.5kg/t, and the sphere is added after the circulation is 1-3min. Carry out the pouring, continuous casting with full protection casting.

Example 7

The outer shell of the composite sphere is prepared by mixing 8% of clay with calcium oxide; the core is 75% by weight of rare earth oxide; 18% of calcium carbonate; 5% of ordinary cement and 2% of bentonite. According to the above ratio, the solid raw material required for the core is crushed and crushed, and at the same time, the airflow is micromilled to obtain a particle size of 40 nm to 3 mm, and the powder is placed in the mixer for thorough mixing and mixing. The material time is l~3h. The mixed raw materials are dried in a drying apparatus, and the drying temperature is 80 to 150 ° C, and the time is 2 to 3 hours. The raw material after the drying treatment is made into a ball on a disc pelletizer by a rolling method, and the rotation speed of the disc pelletizer is 400 to 1600 r/min, and the control of the sphere size is determined by screening, and the diameter of the sphere is obtained as 5~ 30mm. The powder required for taking the outer casing according to the above ratio is thoroughly mixed in the mixer, the activity of calcium oxide is 200 ml, and the mixing time is 1 to 3 hours. The prepared core sphere and the shell material are compositely ball-formed on a disc pelletizer by a rolling method, and the size of the sphere is controlled by screening, and the prepared composite sphere has a size of 20 to 50 mm. Others are the same as in Example 1, and are not described again.

According to the formulation ratio, Ca065%, Al ₂ 0 ₃ 15%, Si0 ₂ 8%, CaF ₂ 12%, the method for preparing the low melting point premelted slag powder is the same as in the first embodiment; the prepared low melting point premelted slag powder 1 is prepared. %, calcium carbonate 1%, magnesia 98% into the vertical mixing mixture 2~8h; and then dry processing on the drying equipment, drying temperature is 80~200 °C, time is 8~20h For the finished powder. Cool to room temperature and put into ultra-thin high-strength polyethylene plastic bag, moisture-proof sealed package 500kg / bag, package to ensure good sealing, prevent moisture, and use within 20 days.

After deoxidation of the molten steel, after the LF, VD or CAS-OB refining is finished, the powder is sprayed into the molten steel, the conveying gas is C0 ₂ , the conveying pressure is controlled at 0.01 to 2.0 MPa, and the powder conveying amount is 0.01 to 3.5 kg/s. Move out and transport the ladle to the RH station for refining. When sampling and analyzing the oxygen content of the molten steel at 0.0001 ~ 0.008%, the composite sphere with the core mainly as the beneficial oxide and expansion agent is added into the molten steel during the RH refining process, and is added to the discharge pipe at the opposite side of the downcomer. The amount of addition is 0.5~3.5kg/t. After the sphere is added, it is transferred for 1~5min and then poured out. The continuous casting adopts full-scale protection pouring.

In order to better illustrate the effect of the process for preparing fine oxide dispersion steel by the present invention, the following comparative tests were carried out: Invention example:

The carbon content of the produced variety is 0.0030%. The carbon content of the converter tapping steel is controlled to be 0.03 to 0.04%. Adjust the position of the RH down tube and the lower tube so that it is on the opposite side of the lower tube. After the molten steel is transported to the RH station, the temperature is sampled. The actual temperature of the molten steel in the smelting process is higher than the required temperature by 5~10 °C, and the composition is adjusted, when the alloying is finished, and when the vacuum of the vacuum chamber is 80~350Pa, The alloy silo was put into the composite sphere containing the second core in Example 6, and was circulated for 1 to 15 minutes after the addition. The feed rate is 0.3 to 1.5 kg/t, and the feed rate is 0.01 to 2.0 kg/s. When sampling and analyzing the oxygen content of the molten steel at 0.0001 to 0.008%, the composite sphere containing the first core in Example 6 is added to the molten steel during the RH refining process, and is added to the discharge pipe at the opposite side of the downcomer. The addition amount is 0.5~3.5kg/t, the single addition amount is 50~130kg, the two addition intervals are 0.1~5min, and the sphere is added at least after circulating for l~10min. The continuous casting adopts full-scale protection casting.

Comparative example: The carbon content of the produced varieties is 0.0030%, and the carbon content of the converter tapping steel is controlled to 0.03~0.04%. After 100 tons of steel water is transported to the RH station, the temperature is sampled, and the continuous casting is fully protected. Table 1

It can be seen from Table 1 that the additive of the present invention makes the oxide inclusions finer and dispersed.

Claims

Rights request

An additive for preparing a fine oxide dispersion steel, characterized in that it is a composite sphere composed of a core and an outer shell, and the outer shell is mainly composed of a mixture of one or two of calcium oxide or magnesium oxide. .

2. An additive according to claim 1 wherein said core is prepared from the following materials in percentage by weight:

Beneficial oxide 0.1%~99%

Expansion agent 1%~70%

Binder 0~30%

3. The additive of claim 1 wherein said core is prepared from the following materials in percentage by weight:

Beneficial oxide 30%~80%

Expansion agent 8%~55 %

Binder 5 %~15 %

4. The additive of claim 1 wherein said core is prepared from the following materials in percentage by weight:

Low melting point pre-slag powder 1%~70%

Expansion agent 1%~60%

Calcium fluoride 0~40%

Binder 0~20%

5. The additive according to claim 1, wherein the core is prepared from the following raw materials in percentage by weight:

Low melting point pre-slag powder 10%~50%

Expansion agent 10%~45% Calcium fluoride 5%~30%

Binder 5%~15%

6. The additive of claim 1 wherein said outer shell further comprises 0 to 20

% binder.

The additive according to claim 2 or 3, characterized in that the beneficial oxide is any one of CaO, Ti ₂ O ₃ , 210 ₂ and rare earth oxide.

The additive according to claim 7, wherein said rare earth oxide is any one of Ce, Nd, La, Gd, and Sm oxides.

9. An additive for the preparation of fine oxide-dispersed steel, characterized by a powder consisting essentially of a low-melting pre-slag powder and a mixture of a swelling agent and one or both of calcium oxide or magnesium oxide.

10. An additive according to claim 9 which is prepared from the following raw materials in weight percent:

Expansion agent 1%~60%

Low melting point pre-slag powder 1%~70%

Calcium oxide or magnesium oxide or a mixture of calcium oxide and magnesium oxide 10%~98%

Calcium fluoride 0~40%

Binder 0~20%

The additive according to claim 9, which is mainly prepared from the following raw materials in a percentage by weight:

Expansion agent 10%~45%

Low melting point pre-slag powder 10%~50%

Calcium oxide or magnesium oxide or a mixture of calcium oxide and magnesium oxide 30%~70%

Calcium fluoride 5%~30%

Binder

12. An additive according to claim 9, 10 or 11 wherein said expansion agent is comprised of carbon A mixture of calcium acid, magnesium carbonate or calcium carbonate and magnesium carbonate.

13. The additive of claim 9 wherein said additive further comprises a cored dosage form.

The additive according to claim 9, 10 or 11, wherein said low-melting pre-slag powder is prepared by weighting the following raw materials: CaO 10% to 70%, A1 ₂ 0 ₃ 15%~50%, Si0 ₂ 0~10%, MgO 0~10%, CaF ₂ 0~30%, and its melting point is from 1100 °C to 1550 °C.

The additive according to claim 10 or 11, wherein the binder is any one or a mixture of two or more of clay, ordinary cement, bentonite, and water glass.

16. A process for the preparation of the additive of claim 1 comprising the steps of:

1), preparation of the core:

(a) Mixing: The raw materials required for the core are crushed, ground and ground to a particle size of 1 nm to 3.5 mm, and the above-mentioned powder and binder are placed in a mixer. Mix well and mix, mixing time is lh~3h for use.

(b) Drying: The above mixed powder is dried in a dryer, and the drying temperature is 80 ° C to 150 ° C, and the time is 2 h to 8 h.

(c), ball core: The powder after the above drying treatment is passed through a ball making device to make a core having a diameter of 0.05 mm to 40 mm.

2) Preparation of composite spheres and pellets:

(d) Preparation of the outer casing: The raw materials required for the outer casing are thoroughly mixed in the mixer according to the ratio. The activity of calcium oxide and magnesium oxide is 200 ml, and the mixing time is l h~3 h.

(e), compounding: The above-mentioned prepared core and shell material are compositely ball-formed on a ball-making device by a rolling method, wherein the prepared composite sphere has a size of 20 to 80 mm; the diameter of the prepared composite pellet is controlled at 0.25~20mm.

(f), overall drying: the composite spheres and pellets prepared in the above steps are respectively dried in the dryer Reason, the drying temperature is 60 ° C ~ 200 ° C, the time is 10 h ~ 24h.

(g), Packing: After drying, cool to room temperature and bag, the weight is 10 kg ~ 30kg / bag, the packaging should ensure good sealing, prevent moisture, and use within 20 days.

17. A process for the preparation of the additive of claim 9 comprising the steps of:

1 Mixing powder: According to the formula ratio, the low melting point premelted powder with a particle size of lnm~3.5mm, calcium fluoride, calcium carbonate, magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate, calcium oxide, magnesium oxide or Mixture of calcium oxide and magnesium oxide and binder into the mixer for thorough mixing and mixing, mixing time lh~8 ho

2 drying treatment: The above prepared powder is dried in a drying apparatus at 80 ° C ~ 200 ° C, the time is 2 1! ~ 24h is the finished powder.

3 line: a low carbon steel strip with a thickness of 2mm~5 mm is used as the outer skin of the cored wire, and the core powder is the finished powder prepared in step 2 on the line making machine, and the single layer steel strip is used to make the core wire. The wire speed is 8~30m/min, and the core powder content is 100~240g/m.

4 Packing: Cool to room temperature, pack the powder into 500~1000kg/bag, pack the core wire into 1000~2000m/roll, ensure the seal is good, prevent moisture, and use within 20 days.

18. A process for preparing fine oxide dispersed steel, comprising the steps of: I. Removal of deoxidation product: a method of feeding directly through a feed line, dusting, shot or sphere after deoxidation of molten steel The core wire, the powder, the composite ball pellet and the composite sphere of the additive are fed to the molten steel at LF, RH, VD or CAS-OB, wherein the core of the composite pellet and the composite sphere is mainly a low melting point premelted slag Powder, expansion agent.

II. Formation of dispersed oxides: When the oxygen content of the molten steel is 0.0001% to 0.008%, the composite spheres with the core mainly beneficial oxides and expansion agents are added to the molten steel during the RH refining process, and the amount of the composite spheres is added. It is 0.5~3.5kg/t, the single addition amount is 50~130kg, and the addition speed is 0.1~1.5kg/s.

19. The process according to claim 18, characterized in that the powder, core wire, composite sphere, compound of the additive fed to the molten steel at LF, RH, VD or CAS-OB according to step I Hefei pill -

(1) The powder is sprayed into the molten steel after the refining of LF, RH, VD or CAS-OB, and the conveying gas is a mixed gas of either or both of Ar and C0 ₂ , and the conveying pressure is controlled at 0.01 to 2.0 MPa, powder The feed rate is 0.3 to 1.5 kg/t at the feed rate and 0.01 to 3.5 kg/s at the feed rate.

(2) The core wire is fed after the alloying of LF, RH, VD or CAS-OB in the late stage of refining. The argon mixing is stopped during the feeding process. The feeding speed is 180~350m/min, and the feeding amount is 0.3~1.5. Kg / t, after the feeding line is still 0.5~10min, and then lightly argon blowing, the flow rate of argon is 50~280Nl/min, and the time of weak argon blowing is 0.5~5min.

(3) The composite sphere is added at the end of the RH refining process, and the vacuum of RH is 66.7~500Pa. The inlet is placed at the discharge pipe on the opposite side of the downcomer, and is circulated for 1 to 15 minutes after the addition. The feed rate is 0.3 to 1.5 kg/t, and the feed rate is 0.01 to 2.0 kg/s.

(4) The composite pellets are shot at the late stage of LF, RH or CAS-OB refining, using argon as the carrier, and the gas pressure is controlled at 0.1 to 1.0 MPa. The injection rate is 0.5 to 5 kg/t, and the feed rate is 0. l~3.0 kg/s.