CN114351035B - Argon station pre-refining method for improving purity of bearing steel - Google Patents
Argon station pre-refining method for improving purity of bearing steel Download PDFInfo
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Abstract
An argon-passing station pre-refining method for improving the purity of bearing steel belongs to the technical field of metal smelting. According to the method, a deoxidizer, a recarburizer, an alloy and pre-refining slag are sequentially added at intervals in the tapping process, wherein the adding amount of aluminum is controlled to be 83-88% of the total adding amount of aluminum, the adding amount of ferrochrome is controlled to be 90-95% of the total adding amount of chromium, and the adding amount of silicon is controlled to be 52-60% of the total adding amount of silicon; before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag amount of the LF refining slag is 0.48-1.00; pre-refining in argon station to melt the pre-refined slag and absorb impurity, and controlling the slag components in the range of 56-60% omega (CaO), 2-4% omega (MgO) and omega (Al) 2 O 3 )28～33％，ω(SiO 2 )3 to 7 percent of the total weight of the alloy, and 0.2 to 0.6 percent of omega (FeO + MnO), wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio is controlled within the range of 0.22-0.38. The method realizes early removal, generation and size control of the inclusions.
Description
Technical Field
The invention relates to the technical field of metal smelting, in particular to an argon station passing pre-refining method for improving the purity of bearing steel.
Background
The formation of large-size inclusion is closely related to the control of a metallurgical process, and the process route of 'a primary smelting furnace (a converter or an electric furnace) + an LF refining furnace + an RH/VD vacuum refining furnace + casting' is commonly adopted for the smelting of the bearing steel at present, wherein steel slag discharged from the primary smelting furnace is mixed and involved, and the reaction, mass transfer and modification of high-alkalinity refining slag and molten steel in the refining process become important sources of the large-size inclusion. In order to improve the purity of bearing steel, Chinese patent CN109402327B discloses an external refining production method of ultrapure high-carbon chromium bearing steel, which comprises the steps of carrying out RS slag skimming operation after BOF converter smelting steel tapping, removing slag in a steel ladle and adding refining slag in LF refining, effectively controlling uncertain factors such as tapping slag, deoxidation products and the like, and being beneficial to quality stability control of bearing steel. Chinese patent CN111793772A discloses a high-standard efficient production process for bearing steel, which cancels the working procedure of an LF refining furnace, solves the problem of large temperature drop of molten steel in the tapping process by adopting an alloy melting furnace to heat alloy, ensures that the molten steel can be directly subjected to vacuum treatment on an RH station after tapping, avoids slag entrapment in the refining process, reduces the denaturation of alumina inclusions to calcium aluminate, but does not consider the removal of liquid inclusions formed in the slag entrapment in the tapping process, has high requirements on smelting control temperature of a converter and low requirements on a terminal point C, can cause the oxygen source in steel to be greatly increased, increases the number of inclusions, is difficult to ensure the quality stability of products, and still has defects in the aspect of purity control.
In light of the above problems, improvements are needed in methods for controlling inclusions in bearing steel to achieve the removal, generation and size control of inclusions.
Disclosure of Invention
The embodiment of the invention aims to provide an argon-passing station pre-refining method for improving the purity of bearing steel, which can realize early removal, generation and size control of inclusions.
The invention is realized by the following steps:
the invention provides an argon station pre-refining method for improving the purity of bearing steel, which comprises primary smelting, tapping, argon station pre-refining, LF refining furnace, vacuum refining furnace and protective pouring and is characterized in that,
sequentially and intermittently adding a deoxidizing agent, a recarburizing agent, an alloy and pre-refining slag in the tapping process, wherein the adding amount of aluminum is controlled to be 83-88% of the total adding amount of aluminum, the adding amount of ferrochrome alloy is controlled to be 90-95% of the total adding amount of chromium, and the adding amount of silicon is controlled to be 52-60% of the total adding amount of silicon;
before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag amount of the LF refining slag is 0.48-1.00;
pre-refining treatment in an argon station to ensure that the pre-refining slag is fully melted and absorbs impurities, and the control range of the slag components after reaction is 56-60 percent of omega (CaO), 2-4 percent of omega (MgO) and 2-4 percent of omega (Al) 2 O 3 )28～33％，ω(SiO 2 )3 to 7 percent of the total weight of the alloy, and 0.2 to 0.6 percent of omega (FeO + MnO), wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio is controlled within the range of 0.22-0.38.
In some examples, the lime addition is adjusted according to different carbon contents in the tapping process, and the specific steps are as follows:
wherein when omega [ C ] is less than 0.1%, the addition amount of lime is 2.8-3.2 kg/t steel, and the addition amount of aluminum is 1.0-1.2 kg/t steel;
when omega [ C ] is 0.1-0.2%, the addition amount of lime is reduced to 2.4-2.8 kg/t steel, and the addition amount of aluminum is 0.8-1.0 kg/t steel;
when omega [ C ] is more than 0.2%, the addition amount of lime is 2.0-2.4 kg/t steel, and the addition amount of aluminum is 0.6-0.8 kg/t steel.
In some examples, the total slag amount before the treatment of the argon station is controlled to be 7.5-11.5 kg/t steel, and the slag amount of LF refining slag is controlled to be 11.5-15.5 kg/t steel.
In some examples of the method of the present invention,
after the argon station arrives at the station for temperature measurement, adjusting the argon flow of each branch to 4-6L/(min t steel), stirring for 5-7min, then adjusting the argon flow to 2-4L/(min t steel), and soft blowing for 2-3 min.
In some examples, the molten steel composition is controlled to satisfy 0.08-0.5% of omega C, less than or equal to 0.017% of omega P, 0.01-0.03% of omega O and 1580-1680 ℃ of molten steel temperature at the end of smelting in the primary smelting furnace.
In some examples, when tapping is prepared after smelting in a primary smelting furnace, if a converter is adopted, a conical slag-stopping cap is used for blocking a tapping hole before tapping, so that tapping can be performed, and steel retaining operation is adopted in the later stage of tapping, wherein the steel retaining amount accounts for 3-5% of the total steel amount; if an electric furnace is adopted, the steel is quickly tilted when the steel tapping amount accounts for 95-97% of the total steel amount.
In some examples, the composition of the molten steel is such that the composition of the molten steel satisfies 0.8 to 0.9% omega C, 0.1 to 0.2% omega Si, 0.9 to 1.4% omega Cr, 0.1 to 0.3% omega Mn, 0.05 to 0.07% omega Al, 0.0045% omega O and 1530 to 1580 ℃ before the argon pre-refining treatment.
In some examples, the composition of the molten steel is controlled by argon treatment to satisfy 0.82-0.92% of omega C, 0.08-0.18% of omega Si, 0.9-1.4% of omega Cr, 0.1-0.3% of omega Mn, 0.03-0.05% of omega Al, less than or equal to 0.0020% of omega O, and 1450-1550 ℃ for the temperature of the molten steel.
In some examples, the ladle is completely processed along the steel slag, and the width of the residual steel slag is less than or equal to 50 mm; the weight of the residue after cleaning in the steel ladle is less than or equal to 150 kg; the nozzle bowl has no residual slurry, the nozzle hole is not blocked, and the temperature of a steel ladle used for tapping reaches over 900 ℃.
In some of the examples of the method,
the method for inspecting the bottom blowing system and the air permeability of the steel ladle comprises the following steps:
and (3) testing gas, setting the flow of the calibrated argon gas to be 7.5-11.5L/(min. t steel), setting the bottom blowing pressure to be more than or equal to 1.0MPa, and setting the actual flow/calibrated flow to be more than or equal to 0.5.
The beneficial effects of the invention include:
on the basis of primary smelting furnace smelting, LF refining furnace and vacuum refining furnace, argon station pre-refining is added, the adding proportion of slag, alloy and the like in the tapping process is optimized, the generation amount of inclusions is reduced, the floating removal effect of the inclusions is improved, the generation of low-melting-point inclusions is reduced, and the size of the inclusions is reduced. The large proportion of ferrochromium alloy is added in the tapping process, and the adding proportion in LF refining is reduced by improving the adding amount of ferrochromium in tapping, so that the aluminum loss in the refining process can be reduced, and the generation amount of inclusions can be reduced. A large proportion of aluminum is added in the steel tapping, the adding proportion of silicon is reduced, and high-melting-point impurities of high alumina are formed in the argon station treatment process by controlling high Al and low Si, so that the floating removal efficiency of the impurities is improved, and the purity of molten steel is improved. By increasing the slag amount of the refining slag in the argon station, reducing the slag amount of the LF refining slag, reasonably controlling the composition of the refining slag, and particularly optimizing CaO/(Al) 2 O 3 ·SiO 2 ) The method has the advantages that the refining process of the argon station is controlled and strengthened, the generation and removal of the inclusion are reasonably controlled, part of inclusion control tasks of the LF refining slag are shared, the inclusion removal effect can be improved, the purity of molten steel is improved, the LF refining time is shortened, and the production efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 microscopic inclusions of magnesium aluminate spinel type;
FIG. 2 Ds-type microscopic inclusions of comparative example 1;
FIG. 3 SEM morphology of macroscopic inclusions of comparative example 1;
FIG. 4 Ds type micro-inclusions of comparative example 2;
figure 5 SEM morphology of macroscopic inclusions of comparative example 2.
Detailed Description
Bearing steel is the steel used to make balls, rollers and bearing rings. Bearing steels have high and uniform hardness and wear resistance, as well as a high elastic limit. The requirements on the uniformity of chemical components of bearing steel, the content and distribution of non-metallic inclusions, the distribution of carbides and the like are all very strict, and the steel is one of the most strict steel types in all steel production.
One of the important characteristics of the cleanliness of steel is the amount of non-metallic inclusions contained in the steel, and the higher the cleanliness, the less the non-metallic inclusions in the steel. Oxide inclusions in bearing steel are the main reasons for causing early fatigue spalling of the bearing and obviously reducing the service life of the bearing, particularly the brittle inclusions have the greatest harm and are easy to spall from a metal matrix in the machining process, and the surface quality of a bearing part after finish machining is seriously influenced; in the service process, the fatigue life is greatly shortened due to stress concentration caused by difficult deformation and crack sources. Therefore, in order to improve the service life and reliability of bearing steel products, the smelting process must be strictly controlled, the content of inclusions in the bearing steel is reduced, and the quantity, size and distribution condition of the inclusions are controlled.
The typical process flow is as follows: 90 tons and above converter smelting → 100 tons and above LF furnace refining → 100 tons and above RH furnace vacuum processing → continuous casting of alloy steel square billet or rectangular billet → (such as 320mm x 340mm and 240mm x 240mm) slow cooling or hot conveying → rolled material → finishing → inspection and warehousing. Through research and demonstration, the process requirements are continuously improved, and the inventor finds that the addition of argon station pre-refining and optimization process in LF furnace refining has an important influence on the control of impurities and the improvement of molten steel cleanliness.
The invention provides an argon-passing station pre-refining method for improving the purity of bearing steel based on the inclusion control requirement in the bearing steel smelting, and the steps of the argon-passing station pre-refining method for improving the purity of bearing steel in the embodiment of the invention are explained in detail below.
The invention adopts the following smelting method:
(1) a primary smelting furnace smelting process.
The smelting is carried out by adopting a converter or an electric furnace.
If converter steelmaking is adopted, the process of the oxygen top-blown converter steelmaking equipment is preferably adopted. According to the material mixing requirement, firstly, the scrap steel and the like are put into a furnace, then the molten iron is poured, and a proper amount of slagging material (such as quicklime and the like) is added. After charging, an oxygen lance is inserted into the furnace from the top of the furnace, and oxygen (high-pressure oxygen flow with purity of more than 99%) is blown in to directly perform oxidation reaction with high-temperature molten iron to remove impurities. After most of sulfur and phosphorus are removed, the components of the molten steel are controlled to meet omega [ C ] 0.08-0.5%, and optionally: 0.08%, 0.10%, 0.17%, 0.23%, 0.28%, 0.32%, 0.36%, 0.44%, 0.48%, 0.50%, etc., ω [ P ] less than 0.017%, optionally: 0.017%, 0.011%, 0.009%, 0.007%, etc., 0.01-0.03% of ω [ O ], optionally: 0.01%, 0.02%, 0.03% and the like, the temperature of the molten steel is 1580-1680 ℃, and optionally: 1580 deg.C, 1593 deg.C, 1613 deg.C, 1626 deg.C, 1637 deg.C, 1643 deg.C, 1646 deg.C, 1657 deg.C, 1666 deg.C, 1672 deg.C, 1680 deg.C, etc.
And when the components and the temperature of the molten steel meet the requirements, stopping converting, lifting the spray gun, and preparing for tapping. When tapping, the furnace body is inclined, molten steel is poured into a ladle from a tapping hole, and simultaneously, a deoxidizer is added for deoxidation and component adjustment. In order to prevent the oxidizing slag of the converter from flowing into a steel ladle, a conical slag blocking cap is used for blocking a steel tapping hole before steel tapping so as to enable steel tapping, and steel retaining operation is adopted in the later stage of steel tapping, wherein the steel retaining amount accounts for 3-5% of the total steel amount, and is selected from 3%, 4%, 5%, and preferably 4%.
If the electric furnace is adopted for steelmaking, furnace types such as an ultrahigh-power eccentric bottom tapping electric furnace, a direct current electric arc furnace and the like are adopted, arc heat is mainly utilized, the smelting process is generally divided into a melting period, an oxidation period and a reduction period, dephosphorization and desulfurization are carried out, and the components and the temperature of molten steel are adjusted to meet the target requirements. After most of sulfur and phosphorus are removed, the composition of the molten steel is controlled to meet omega [ C ] 0.08-0.5%, and optionally: 0.08%, 0.10%, 0.17%, 0.23%, 0.28%, 0.32%, 0.36%, 0.44%, 0.48%, 0.50%, etc., ω [ P ] less than 0.017%, optionally: 0.017%, 0.011%, 0.009%, 0.007%, etc., 0.01-0.03% of ω [ O ], optionally: 0.01%, 0.02%, 0.03% and the like, the temperature of the molten steel is 1580-1680 ℃, and optionally: 1580 deg.C, 1593 deg.C, 1613 deg.C, 1626 deg.C, 1637 deg.C, 1643 deg.C, 1646 deg.C, 1657 deg.C, 1666 deg.C, 1672 deg.C, 1680 deg.C, etc.
And when the components and the temperature of the molten steel meet the requirements, stopping smelting and preparing for tapping. When the proportion of the tapping amount to the total steel amount is 95-97% (optionally 95%, 96%, 97% and the like) during tapping, the tapping is stopped by quickly inclining back, and oxidizing slag is prevented from flowing into a ladle.
Further, the ladle condition guarantees that: the ladle is cleaned along the steel slag, and the width of the residual steel slag is less than or equal to 50 mm; the ladle can not contain obvious scum, floating bricks and loose refractory materials, and the weight of the residue after cleaning is less than or equal to 150 kg. The temperature of a steel ladle used for tapping reaches over 900 ℃. By controlling the ladle condition, the influence of the slag residue on the purity of the filled bearing steel liquid is avoided.
Further, after the molten steel with the components and the temperature reaching the target is obtained through the smelting process, the addition amount of deoxidizers, alloys and the like in the tapping process needs to be strictly controlled.
In the tapping process, a deoxidizer, a recarburizing agent, an alloy, lime and pre-refining slag are sequentially added at intervals, wherein the deoxidizer is preferably aluminum iron or aluminum ingot, is not particularly limited and can be other aluminum-containing deoxidizers; the alloy comprises ferrochrome, ferromanganese, aluminum iron and other alloys containing the components required by the bearing steel.
In the general smelting process, most of ferrochrome is added with adjusting components in LF, and mainly for improving the yield of ferrochrome, the inventor finds that the adding time of most of ferrochrome is adjusted to the adding of tapping, so that the adding amount in the LF refining process is reduced, and the method has very beneficial effects on controlling the aluminum loss and the generation amount of inclusions in the refining process. Controlling the addition amount of alloy in the tapping process, particularly improving the addition amount of ferrochrome, wherein the addition amount of ferrochrome is controlled according to 90-95% of the total addition amount, and can be selected from 90%, 91%, 92%, 93%, 94%, 95% and the like. The large proportion of ferrochromium alloy is added in the tapping process, and the adding proportion in LF refining is reduced by improving the adding amount of ferrochromium in tapping, so that the aluminum loss in the refining process can be reduced, and the generation amount of inclusions can be reduced.
The inventors have found that varying the carbon content during tapping results in varying oxygen content, that varying the amount of aluminium and silicon added results in different types and amounts of oxide inclusions, that varying the amount and composition of the steel slag has an effect on the oxide absorption capacity, and that the addition of such materials affects the amount and type of oxide produced and the capacity of the slag to absorb the oxides. In order to ensure the full inclusion absorption capacity of the refining slag, the addition amount of lime is adjusted according to different carbon contents in the tapping process, and the method specifically comprises the following steps:
when omega [ C ] is less than 0.1%, the adding amount of lime is 2.8-3.2 kg/t steel, optionally 2.8kg/t steel, 2.9kg/t steel, 3.0kg/t steel, 3.1kg/t steel, 3.2kg/t steel and the like, and the adding amount of aluminum is 1.0-1.2 kg/t steel, optionally 1.0kg/t steel, 1.1kg/t steel, 1.2kg/t steel and the like; the quantity of oxides formed by the molten steel is large, and the addition amount of the lime and the addition amount of the aluminum are controlled, so that the oxide absorption capacity of the slag is improved, the impurity removal effect is improved, and the effect of better improving the purity of the molten steel is achieved.
When omega [ C ] is 0.1-0.2%, the adding amount of lime is reduced to 2.4-2.8 kg/t steel, optionally 2.4kg/t steel, 2.5kg/t steel, 2.6kg/t steel, 2.7kg/t steel, 2.8kg/t steel and the like, and the adding amount of aluminum is 0.8-1.0 kg/t steel, optionally 0.8kg/t steel, 0.9kg/t steel, 1.0kg/t steel and the like; the quantity of oxides formed by the molten steel is reduced, and the addition amount of the lime and the addition amount of the aluminum are controlled, so that the oxide absorption capacity of the slag is properly reduced, the removal effect of inclusions is ensured, the amount of the slag is properly adjusted, and the effect of better improving the purity of the molten steel is achieved.
When omega [ C ] is more than 0.2%, the lime is added in an amount of 2.0-2.4 kg/t steel, optionally 2.0kg/t steel, 2.1kg/t steel, 2.2kg/t steel, 2.3kg/t steel, 2.4kg/t steel and the like, and the aluminum is added in an amount of 0.6-0.8 kg/t steel, optionally 0.6kg/t steel, 0.7kg/t steel, 0.8kg/t steel and the like. The quantity of oxides formed in the molten steel is further reduced, the lime addition and the aluminum addition are controlled, the oxide absorption capacity of the slag is properly reduced, the inclusion removal effect is ensured, the slag quantity is properly adjusted, and the effect of better improving the purity of the molten steel is achieved.
In the general smelting process, materials such as an aluminum-containing deoxidizer and the like have good deoxidizing effect, most of the materials are supplemented in LF refining except the addition in the tapping process, but alumina impurities generated by later-stage aluminum supplement are difficult to remove, the purity of molten steel is influenced, and the risk of nozzle nodulation is increased. The inventor finds that materials such as an aluminum-containing deoxidizer and the like are added in the tapping process, the aluminum supplement amount in the later period of LF is reduced, the adding amount of the tapping Si alloy is controlled, high-melting-point inclusions which are easy to remove are formed by controlling high Al and low Si, the floating removal efficiency of the inclusions is improved by utilizing the dynamic condition of an argon station, and the purity of molten steel is improved.
Wherein the addition of aluminum-containing deoxidizer is controlled, so that the amount of the added metal aluminum in the steel tapping is controlled to be 83-88% of the total addition amount, and can be selected from 83%, 84%, 85%, 86%, 87%, 88% and the like; the adding amount of the silicon is controlled within the range of 52-60% of the total adding amount, and can be selected from 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60% and the like. The large proportion of aluminum is added in the tapping, the adding proportion of silicon is reduced, high-melting-point inclusions of high alumina are formed in the argon station treatment process by controlling high Al and low Si, and the characteristic of good power condition of the argon station is fully utilized, so that the floating removal efficiency of the inclusions is improved, the purity of molten steel is improved, meanwhile, the LF refining process is ensured to reach the process target, and the LF refining time can be shortened.
In the general smelting process, inclusion is removed and alloy components are adjusted mainly by LF refining, and the pretreatment in an argon station is only used for floating the existing inclusion in molten steel, so that the quantity of LF refining slag is large, and the quantity of argon station pretreatment refining slag is small. The inventor finds that the slag amount of the argon station pretreated refining slag is increased, the slag components are controlled, the generation and removal processes of the inclusion in the refining process of the argon station can be realized, the argon station has good conditions for removing the inclusion dynamically, the purification effect of molten steel can be improved, the burden of LF refining is reduced, and the time of LF refining process is shortened.
Before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag amount of the LF refining slag is 0.48-1.00, and can be selected from 0.48, 0.49, 0.51, 0.52, 0.56, 0.59, 0.61, 0.65, 0.67, 0.71, 0.78, 0.83, 0.86, 0.87, 0.89, 0.91, 0.93, 0.94, 0.97, 0.98, 0.99, 1.00 and the like. In some examples, the total amount of slag before argon station treatment is controlled to be 7.5-11.5 kg/t steel, and can be selected from 7.5kg/t steel, 7.7kg/t steel, 7.9kg/t steel, 8.3kg/t steel, 8.6kg/t steel, 8.8kg/t steel, 8.9kg/t steel, 9.2kg/t steel, 9.4kg/t steel, 9.7kg/t steel, 9.9kg/t steel, 10.1kg/t steel, 10.3kg/t steel, 10.6kg/t steel, 10.8kg/t steel, 10.9kg/t steel, 11.3kg/t steel, 11.4kg/t steel, 11.5kg/t steel and the like.
Before the pre-refining treatment in the argon station, the molten steel components are 0.8-0.9% of omega C, 0.1-0.2% of omega Si, 0.9-1.4% of omega Cr (optionally 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, etc.), 0.1-0.3% of omega Mn, 0.05-0.07% of omega Al (optionally 0.05%, 0.06%, 0.07%, etc.), not more than 0.0045% of omega O, 1530-1580 ℃, optionally 1530-3 ℃, 1533 ℃, 1543 ℃, 1547 ℃, 1556 ℃, 1559 ℃, 1563 ℃, 1567 ℃, 1569 ℃, 1 ℃, 1573 ℃, 1577 ℃, 1580 ℃ and the like. The steel tapping end point components and the temperature of the primary smelting furnace are strictly controlled, and a proper deoxidizer and the addition amount of slag charge are added according to the carbon content of the steel tapping, so that the components of the steel slag are accurately controlled, the fluidity of the refined slag and the absorption capacity of inclusions are further improved, and the process stability is high.
By increasing the slag amount of the refining slag in the argon station, reducing the slag amount of the LF refining slag, reasonably controlling the composition of the refining slag, and particularly optimizing CaO/(Al) 2 O 3 ·SiO 2 ) The refining process of the argon station is controlled and strengthened, the generation and removal of inclusions are reasonably controlled, part of inclusion control tasks of LF refining slag are shared, the inclusion removal effect can be improved, the purity of molten steel is improved, the LF refining time is shortened, and the production efficiency is improved.
(2) And pre-refining in an argon station.
The main purpose is to homogenize the components and temperature of the molten steel; the slag rolling and the floating of inclusions generated by deoxidation in the tapping process are promoted by virtue of the dynamic condition of good argon stirring; the pre-refining slag melting and the absorption of the impurities are promoted to inspect the bottom blowing system and the air permeability of the ladle.
The double-air brick is adopted for bottom blowing, the two bottom blowing systems can independently regulate the flow, the flow regulation range is 0-12.5L/(min. t steel), and the pressure is more than 0.80 MPa. Firstly, setting the calibrated argon flow to be 7.5-11.5L/(min. t steel), setting the bottom blowing pressure to be more than or equal to 1.0MPa, and setting the test gas to be qualified when the actual flow/calibrated flow is more than or equal to 0.5.
After the argon station arrives at the station for temperature measurement, observing the melting condition of a slag sample on the surface of the molten steel, when slag melting is uneven and slag charge and alloy are mixed and accumulated on the surface of the molten steel, increasing the flow of argon of each branch to 4-6L/(min. t steel), stirring for 5-7min, ensuring that the slag charge is uniformly spread on the surface of the molten steel, and then adjusting the flow of the argon to 2-4L/(min. t steel) and soft blowing for 2-3 min; when the slag materials are evenly spread when arriving at the station, the flow of argon is directly adjusted to 2-4L/(min. t steel), and the bottom blowing time is controlled to 6-8 min. Finally, temperature measurement and sampling are carried out, and the alloy amount is definitely added according to the result. The argon station treatment process adopts accurate segmented flow control according to the slag melting condition of tapping, promotes rapid slag melting and reduces slag rolling in the treatment process, thereby reducing the formation of foreign impurities, reducing the burning loss of aluminum in steel and reducing endogenous impurities.
Argon pre-refining treatment to melt the pre-refining slag and absorb impurity, and the slag composition after reaction is controlled in the range of 56-60% (56%, 57%, 58%, 59%, 60%, etc.), 2-4% (2%, 3%, 4%, etc.) and omega (Al) 2 O 3 ) 28-33% (optionally 28%, 29%, 30%, 31%, 32%, 33%, etc.), omega (SiO) 2 ) 3-7% (optionally 3%, 4%, 5%, 6%, 7%, etc.), omega (FeO + MnO) 0.2-0.6% (optionally 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, etc.), wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio is controlled within the range of 0.22-0.38, and can be selected from 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38 and the like. The above-mentioned pre-refining slag composition control, especially CaO/(Al) 2 O 3 ·SiO 2 ) The control of the argon station refining slag can improve the capability of absorbing the inclusions in the argon station refining slag, the slag amount is approximately the same as the tapping slag amount, the generation and removal of the inclusions are reasonably controlled, part of the inclusion control tasks of the LF refining slag are shared, the argon station refining slag has stronger inclusion removal capability, and the excellent dynamic conditions of the Ar station have better argon station refining effect and can create good conditions for shortening the LF refining time.
By argon treatment, the composition of the molten steel is controlled to satisfy 0.82-0.92% of omega C, 0.08-0.18% of omega Si, 0.9-1.4% of omega Cr (optionally 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, etc.), 0.1-0.3% of omega Mn, 0.03-0.05% of omega Al (optionally 0.03%, 0.04%, 0.05%, etc.), 0.0020% or less of omega O, 1450-1550 deg.C, 1460 deg.C, 1470 deg.C, 1480 deg.C, 1490 deg.C, 1500 deg.C, 1510 deg.C, 1530 deg.C, 1543 deg.C, 1550 deg.C, etc.
(3) LF refining
Refining and heating components of an LF furnace to finely adjust impurities, wherein the slag amount of LF refining slag is controlled to be 11.5-15.5 kg/t steel, and can be selected from 11.5kg/t steel, 11.6kg/t steel, 11.9kg/t steel, 12.3kg/t steel, 12.6kg/t steel, 12.9kg/t steel, 13.3kg/t steel, 13.6kg/t steel, 13.7kg/t steel, 13.9kg/t steel, 14.4kg/t steel, 14.9kg/t steel, 15.3kg/t steel, 15.5kg/t steel and the like; the LF refining process time is controlled within 45-65min, optionally 45min, 46min, 48min, 49min, 53min, 56min, 59min, 61min, 62min, 63min, 64min, 65min and the like, aluminum can be adjusted at the initial stage, the LF furnace temperature is controlled at 1550-1570 ℃, optionally 1550 ℃, 1555 ℃, 1560 ℃, 1563 ℃, 1565 ℃, 1567 ℃, 1569 ℃, 1570 ℃ and the like. Partial refining tasks are shared through the refining treatment of the argon station, the quantity of LF refining slag is reduced, the refining time is reduced, the generation and the residue of inclusions in the LF refining process are greatly reduced, and the purity of molten steel is improved.
(4) Refining in a vacuum refining furnace
Refining in an RH/VD vacuum refining furnace to ensure a longer vacuum time of 28-35min and a certain soft blowing time of 25-35min, and finally performing protective pouring to protect a water gap bowl from slurry residue and prevent a water gap hole from being blocked during pouring.
The features and properties of the present invention are further described in detail below with reference to examples:
example one
A smelting method for bearing steel includes smelting in a converter, tapping, pre-refining in an argon station, LF refining furnace, vacuum refining furnace and protective casting, wherein the components of molten steel are controlled to meet 0.08% of omega C, 0.015% of omega P and 0.02% of omega O, the temperature of the molten steel is 1639 ℃, steel retaining operation is adopted in the later stage of tapping, the steel retaining amount accounts for 4% of the total steel amount, deoxidizing agents, recarburizing agents, alloys, lime and pre-refining slag are sequentially added at intervals in the tapping process, the deoxidizing agents are aluminum iron, and the alloys include ferrochrome, ferromanganese, aluminum iron, ferrosilicon and other alloys. The addition of the ferrochrome alloy is controlled according to 93 percent of the total addition.
Tapping omega C0.08%, adding lime 2.9kg/t steel, and adding ferro-aluminium 1.2kg/t steel; wherein the addition of aluminum-containing deoxidizer is controlled, the amount of added aluminum and iron is controlled to 84 percent of the total amount of added aluminum according to the amount of added metallic aluminum (the total amount of added aluminum refers to the total amount of added aluminum in the whole smelting process); the amount of silicon and iron added is controlled to be 56% of the total amount of silicon added according to the amount of silicon added (the total amount of silicon added means the total amount of silicon added in the whole smelting process).
Before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag amount of the LF refining slag is 0.77. The total slag amount before the treatment of the argon station is controlled to be 9.11kg/t steel.
Before the pre-refining treatment in argon station, the molten steel has the composition of omega C0.8%, omega Si 0.1%, omega Cr 1.3%, omega Mn 0.2%, omega Al 0.06%, omega O0.0045% and molten steel temperature 1575 deg.c.
(2) And pre-refining in an argon station.
Pre-refining in argon station to melt the pre-refined slag and absorb impurity, and controlling the slag components in omega (CaO) 58%, omega (MgO) 4% and omega (Al) 58% separately 2 O 3 )31％，ω(SiO 2 ) 5%, omega (FeO + MnO) 0.6%, wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio was controlled at 0.36.
The molten steel is treated in argon station to control its composition to meet the requirements of omega C0.82%, omega Si 0.13%, omega Cr 1.3%, omega Mn 0.2%, omega Al 0.03%, omega O0.0019% and molten steel temp. 1490 deg.C.
(3) LF refining
Refining and heating components in an LF furnace to finely adjust impurities, wherein the slag amount of LF refining slag is controlled to be 11.8kg/t steel; the time of the LF refining process is controlled to be 47min, and the temperature of the LF discharged furnace is controlled to be 1567 ℃.
(4) Refining in a vacuum refining furnace
Refining in RH vacuum refining furnace for 29min, soft blowing for 26min, and protective casting.
Through the smelting process, inclusions in the bearing steel are detected by adopting a water immersion flaw detection method and a scanning electron microscope detection method, and the inclusions are mainly found to be fine magnesium aluminate spinel type inclusions and are small in size, and as shown in figure 1, Ds type microscopic inclusions with the size larger than 13 micrometers and macroscopic inclusions with the size larger than 500 micrometers are not found.
Example two
The bearing steel smelting process includes smelting in converter, tapping, pre-refining in argon station, LF refining furnace, vacuum refining furnace and protecting casting, and has molten steel components of 0.2% omega, 0.017% omega, 0.01% omega and 1626 deg.c.
And steel retaining operation is adopted in the later tapping period, and the steel retaining amount accounts for 5% of the total steel amount.
In the tapping process, a deoxidizer, a recarburizer, an alloy, lime and pre-refining slag are sequentially added at intervals, wherein the deoxidizer is ferro-aluminium, and the alloy comprises ferrochrome, ferromanganese, ferro-aluminium, ferrosilicon and other alloys. The addition of the ferrochrome is controlled according to 91 percent of the total addition of the ferrochrome.
Tapping omega C0.2%, adding lime 2.4kg/t steel, adding ferro-aluminium 0.8kg/t steel; wherein, the addition of aluminum-containing deoxidizer is controlled, so that the amount of the added metallic aluminum is controlled to be 85 percent of the total addition amount of the aluminum in the tapping process; the silicon and iron are added in an amount of 57 percent of the total addition of the silicon according to the addition amount of the silicon.
Before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag quantity of the LF refining slag is 0.84. The total slag amount before the treatment of the argon station is controlled to be 10.9kg/t steel.
Before the pre-refining treatment in argon station, the molten steel has the composition including omega C0.9%, omega Si 0.2%, omega Cr 1.4%, omega Mn 0.1%, omega Al 0.05%, omega O0.0035% and molten steel temperature 1571 deg.c.
(2) And pre-refining in an argon station.
Pre-refining in argon station to melt the pre-refined slag and absorb impurity, and controlling the slag components in omega (CaO) 59%, omega (MgO) 2% and omega (Al) 59% after reaction 2 O 3 )32％，ω(SiO 2 ) 6%, 0.6% of omega (FeO + MnO), wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio is controlled at 0.30.
The molten steel is treated in argon station to control its composition to meet the requirements of omega C0.89%, omega Si 0.17%, omega Cr 1.4%, omega Mn 0.1%, omega Al 0.05%, omega O0.0016% and molten steel temp. 1530 deg.C.
(3) LF refining
Refining and heating components in an LF furnace to finely adjust impurities, wherein the slag amount of LF refining slag is controlled to be 12.9kg/t steel; the time of the LF refining process is controlled to be 51min, and the temperature of the LF is 1555 ℃.
(4) Refining in a vacuum refining furnace
Refining in RH vacuum refining furnace for 27min, soft blowing for 25min, and protective casting.
Through the smelting process, the maximum size of the inclusions found in the bearing steel is 8 microns, and Ds type micro-inclusions with the size larger than 13 microns and macro-inclusions with the size larger than 500 microns do not appear.
EXAMPLE III
The bearing steel smelting process includes smelting in converter, tapping, pre-refining in argon station, LF refining furnace, vacuum refining furnace and protecting casting, and has molten steel composition of omega C0.42%, omega P not more than 0.017%, omega O0.03% and molten steel temperature 1643 deg.c.
And steel retaining operation is adopted in the later tapping period, and the steel retaining amount accounts for 3% of the total steel amount.
In the tapping process, a deoxidizer, a recarburizer, an alloy, lime and pre-refining slag are sequentially added at intervals, wherein the deoxidizer is ferro-aluminium, and the alloy comprises ferrochrome, ferromanganese, ferro-aluminium, ferrosilicon and other alloys.
The addition amount of the ferrochrome is controlled by 93 percent of the total addition amount.
0.42% of steel tapping omega C, 2.3kg/t of steel lime and 0.7kg/t of steel aluminum.
Wherein, the addition of aluminum-containing deoxidizer is controlled, so that the amount of the added metallic aluminum in the steel tapping is controlled to 84 percent of the total addition amount; the amount of silicon added was controlled to 53% of the total amount added.
Before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows by adding lime and pre-refining slag at the final tapping stage: the total slag amount of the LF refining slag is 0.63. The total slag amount before the treatment of the argon station is controlled to be 8.9kg/t steel.
Before the pre-refining treatment in argon station, the molten steel has the composition of omega C0.9%, omega Si 0.1%, omega Cr 1.1%, omega Mn 0.3%, omega Al 0.05%, omega O0.0036% and the temperature of molten steel 1577 deg.c.
(2) And pre-refining in an argon station.
Pre-refining in argon station to melt the pre-refining slag and absorb impurity, and controlling the slag components in omega (CaO) 59%, omega (MgO) 3% and omega (Al) 59%, respectively 2 O 3 )31％，ω(SiO 2 ) 6.5%, omega (FeO + MnO) 0.3%, wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio was controlled at 0.29.
The molten steel is treated in argon station to control its composition to meet omega C0.91%, omega Si 0.08%, omega Cr 1.1%, omega Mn 0.3%, omega Al 0.05%, omega O0.0015% and molten steel temp. 1520 deg.C.
(3) LF refining
Refining and heating components in an LF furnace to finely adjust impurities, and controlling the slag amount of LF refining slag to be 14.1kg/t steel; the time of the LF refining process is controlled to be 48min, and the temperature of the LF discharged furnace is controlled to be 1560 ℃.
(4) Refining in a vacuum refining furnace
Refining in RH vacuum refining furnace for 31min and 29min, and final protective casting.
Through the smelting process, Ds type micro-inclusions with the size larger than 13 microns and macro-inclusions with the size larger than 500 microns are not detected in the bearing steel.
Comparative example 1
The smelting process of bearing steel includes smelting in converter, tapping, pre-refining in argon station, LF refining furnace, vacuum refining furnace and protective casting, and has molten steel components of omega C0.5%, omega P not more than 0.017%, omega O0.03% and molten steel temperature 1666 deg.c.
And steel retaining operation is adopted in the later tapping period, and the steel retaining amount accounts for 4% of the total steel amount.
In the tapping process, a deoxidizer, a recarburizer, an alloy, lime and pre-refining slag are sequentially added at intervals, wherein the deoxidizer is ferro-aluminium, and the alloy comprises ferrochrome, ferromanganese, ferro-aluminium, ferrosilicon and other alloys.
The addition of the ferrochrome is controlled by 65 percent of the total addition.
Tapping omega C0.5%, lime adding amount 2.4kg/t steel, and aluminum adding amount 0.8kg/t steel.
Wherein the addition of aluminum-containing deoxidizer is controlled to control the amount of metal aluminum added during tapping to be 70% of the total amount added, and the amount of silicon added to be 75% of the total amount added.
Before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag quantity of the LF refining slag is 0.18. The total slag amount before the treatment of the argon station is controlled to be 3.3kg/t steel.
Before the pre-refining treatment in the argon station, the composition of molten steel is made to meet omega C0.9%, omega Si 0.3%, omega Cr 0.8%, omega Mn 0.3%, omega Al 0.03%, omega O0.0043%, and molten steel temperature 1567 deg.C.
(2) And pre-refining in an argon station.
Pre-refining in argon station to melt the pre-refining slag and absorb impurity, and controlling the slag components in the range of 60 wt% omega (CaO), 2 wt% omega (MgO) and 2 wt% omega (Al) 2 O 3 )33％，ω(SiO 2 ) 4%, 0.6% of omega (FeO + MnO), wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio was controlled at 0.45.
Through argon treatment, the composition of molten steel is controlled to meet the requirements of omega C0.9%, omega Si 0.28%, omega Cr 0.8%, omega Mn 0.3%, omega Al 0.05%, omega O0.0030% and molten steel temp. 1550 deg.C.
(3) LF refining
Refining and heating components in an LF furnace to finely adjust impurities, wherein the slag amount of LF refining slag is controlled to be 18.5kg/t steel; the time of the LF refining process is controlled to be 68min, and the temperature of the LF discharged furnace is controlled to be 1555 ℃.
(4) Refining in a vacuum refining furnace
Refining in RH vacuum refining furnace for 55min and 53min, and protecting and casting.
Through the smelting process, Ds type micro-inclusions with the size of more than 13 microns exist in the bearing steel, the steel is about 40.3 microns and is graded as Ds2.0 grade, the bearing steel mainly contains calcium aluminate, and a small amount of Si is contained, as shown in figure 2; macroscopic inclusions 3.8mm in length were also detected by water immersion flaw detection, as shown in FIG. 3.
Comparative example 2
The smelting process of bearing steel includes smelting in converter, tapping, pre-refining in argon station, LF refining furnace, vacuum refining furnace and protecting casting, and has molten steel components controlled to omega C0.12%, omega P not more than 0.017%, omega O0.03% and molten steel temperature 1643 deg.c.
And steel retaining operation is adopted in the later tapping period, and the steel retaining amount accounts for 3 percent of the total steel amount.
In the tapping process, a deoxidizer, a recarburizer, an alloy, lime and pre-refining slag are sequentially added at intervals, wherein the deoxidizer is ferro-aluminium, and the alloy comprises ferrochrome, ferromanganese, ferro-aluminium, ferrosilicon and other alloys.
The addition of the ferrochrome is controlled by 65 percent of the total addition.
When omega C is 0.12%, the addition of lime is 2.0kg/t steel, and the addition of aluminium is 0.6kg/t steel.
Wherein, the addition of aluminum-containing deoxidizer is controlled, so that the amount of the added metallic aluminum in the tapping is controlled to be 65 percent of the total addition amount; the amount of silicon added was controlled to be within 83% of the total amount added.
Before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag quantity of the LF refining slag is 0.20. The total slag amount before the treatment of the argon station is controlled to be 4.3kg/t steel.
Before the pre-refining treatment in argon station, the components of molten steel are made to meet omega C0.8%, omega Si 0.24%, omega Cr 0.6%, omega Mn 0.1%, omega Al 0.03%, omega O0.0023%, and molten steel temperature 1559 deg.C.
(2) And pre-refining in an argon station.
Pre-refining in argon station to melt the pre-refining slag and absorb impurity, and controlling the slag components in omega (CaO) 52%, omega (MgO) 3% and omega (Al) 52%, 3%, respectively 2 O 3 )34％，ω(SiO 2 ) 10%, omega (FeO + MnO) 0.6%, wherein CaO/(Al) 2 O 3 ·SiO 2 ) The ratio is controlled in the range of 0.15.
The components of molten steel are controlled by argon treatment to meet the requirements of 0.82% of omega C, 0.19% of omega Si, 0.6% of omega Cr, 0.1% of omega Mn, 0.02% of omega Al and 0.0024% of omega O, and the molten steel temperature is 1480 deg.C.
(3) LF refining
Refining and heating components in an LF furnace to finely adjust impurities, wherein the slag amount of LF refining slag is controlled to be 21kg/t steel; the time of the LF refining process is controlled to be 72min, and the temperature of the LF discharged furnace is controlled to be 1563 ℃.
(4) Refining in a vacuum refining furnace
Refining in RH vacuum refining furnace for 55min and 53min, and final protective casting.
Through the above smelting process, the bearing steel found Ds-type microscopic inclusions with a size > 13 μm, with a diameter of about 43 μm as shown in FIG. 4, and macroscopic inclusions with a size > 500 μm, with a length of about 6.5mm as shown in FIG. 5.
The process greatly reduces the addition of alloy and slag in the refining process, effectively avoids slag entrapment in the refining process, can reduce the refining treatment time, effectively controls the denaturation of alumina inclusions to calcium aluminate at high temperature, reduces Ds type microscopic inclusions with the size larger than 13 micrometers and macroscopic inclusions with the size larger than 500 micrometers, and simultaneously improves the production efficiency.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described above. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. The above detailed description of embodiments of the invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
In the present invention, all embodiments, implementations and features of the present invention can be combined with each other without contradiction or conflict. In the present invention, conventional devices, apparatuses, components, etc. are either commercially available or self-made according to the present disclosure. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available. In the present invention, some conventional operations and apparatuses, devices, components are omitted or only briefly described in order to highlight the importance of the present invention.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. An argon station pre-refining method for improving the purity of bearing steel comprises primary smelting furnace smelting, tapping, argon station pre-refining, LF refining furnace, vacuum refining furnace and protective casting, and is characterized in that,
sequentially and intermittently adding a deoxidizing agent, a recarburizing agent, an alloy and pre-refining slag in the tapping process, wherein the adding amount of aluminum is controlled to be 83-88% of the total adding amount of aluminum, the adding amount of ferrochrome alloy is controlled to be 90-95% of the total adding amount of chromium, and the adding amount of silicon is controlled to be 52-60% of the total adding amount of silicon;
before the treatment of the argon station, the total slag amount before the treatment of the argon station is as follows through the addition of lime and pre-refining slag at the final tapping stage: the total slag amount of the LF refining slag is 0.48-1.00;
pre-refining in argon station to melt the pre-refined slag and absorb impurity, and controlling the slag components in the range of 56-60% omega (CaO), 2-4% omega (MgO) and omega (Al) 2 O 3 ）28~33%，ω（SiO 2 ) 3-6% of CaO/(Al + MnO) and 0.2-0.6% of omega (FeO + MnO) 2 O 3 ·SiO 2 ) The ratio is controlled to be 0.30-0.38;
the total slag amount before the treatment in the argon station is controlled to be 7.5-11.5 kg/t steel, and the slag amount of LF refining slag is controlled to be 11.5-15.5 kg/t steel.
2. The pre-refining method for improving the purity of the bearing steel in the argon passing station as set forth in claim 1, wherein the lime addition is adjusted according to different carbon contents in the tapping process, and the method comprises the following steps:
wherein when omega [ C ] is less than 0.1%, the addition amount of lime is 2.8-3.2 kg/t steel, and the addition amount of aluminum is 1.0-1.2 kg/t steel;
when omega [ C ] is 0.1-0.2%, the addition amount of lime is reduced to 2.4-2.8 kg/t steel, and the addition amount of aluminum is 0.8-1.0 kg/t steel;
when omega [ C ] is more than 0.2%, the addition amount of lime is 2.0-2.4 kg/t steel, and the addition amount of aluminum is 0.6-0.8 kg/t steel.
3. The argon-passing station pre-refining method for improving the purity of bearing steel according to claim 1,
after the argon station arrives at the station for temperature measurement, adjusting the argon flow of each branch to 4-6L/(min t steel), stirring for 5-7min, then adjusting the argon flow to 2-4L/(min t steel), and soft blowing for 2-3 min.
4. The pre-refining method of claim 1, wherein the molten steel components are controlled to meet 0.08-0.5% of omega C, less than or equal to 0.017% of omega P, 0.01-0.03% of omega O and 1580-1680 ℃ of molten steel temperature at the end of primary smelting in the primary smelting furnace.
5. The argon station pre-refining method for improving the purity of bearing steel according to claim 1, wherein when steel tapping is prepared after smelting in a primary smelting furnace, if a converter is adopted, steel can be tapped by using a conical slag stopping cap to block a tapping hole before tapping, and steel retaining operation is adopted in the later stage of tapping, wherein the steel retaining amount accounts for 3-5% of the total steel amount; if an electric furnace is adopted, the steel is quickly tilted when the steel tapping amount accounts for 95-97% of the total steel amount.
6. The pre-refining method of claim 1, wherein the composition of the molten steel is 0.8-0.9% of ω C, 0.1-0.2% of ω Si, 0.9-1.4% of ω Cr, 0.1-0.3% of ω Mn, 0.05-0.07% of ω Al, less than or equal to 0.0045% of ω O, and 1530-1580 ℃ of the molten steel before the pre-refining treatment in the argon station.
7. The pre-refining method of claim 1, wherein the composition of the molten steel is controlled by the argon treatment to satisfy 0.82-0.92% of ω C, 0.08-0.18% of ω Si, 0.9-1.4% of ω Cr, 0.1-0.3% of ω Mn, 0.03-0.05% of ω Al, less than or equal to 0.0020% of ω O, and 1450-1550 ℃ of molten steel temperature.
8. The argon station-passing pre-refining method for improving the purity of the bearing steel according to claim 1, wherein a ladle is completely processed along the steel slag, and the width of the residual steel slag is less than or equal to 50 mm; the weight of the residue after cleaning in the steel ladle is less than or equal to 150 kg; the nozzle bowl has no residual slurry, the nozzle hole is not blocked, and the temperature of a steel ladle used for tapping reaches over 900 ℃.
9. The argon-passing station pre-refining method for improving the purity of bearing steel according to claim 1,
the method for inspecting the bottom blowing system and the air permeability of the steel ladle comprises the following steps:
and (3) testing gas, setting the flow of the calibrated argon gas to be 7.5-11.5L/(min. t steel), setting the bottom blowing pressure to be more than or equal to 1.0MPa, and setting the actual flow/calibrated flow to be more than or equal to 0.5.
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| CN104087719B (en) * | 2014-07-04 | 2016-05-04 | 常州东大中天钢铁研究院有限公司 | A kind of smelting process of high carbon bearing steel |
| CN111635980A (en) * | 2020-06-11 | 2020-09-08 | 广东韶钢松山股份有限公司 | Bearing steel tapping alloying control method, bearing steel and preparation method thereof |
| CN112322837B (en) * | 2020-11-05 | 2022-02-01 | 马鞍山钢铁股份有限公司 | Smelting process for efficient slagging and desulfurization of LF (ladle furnace) aluminum killed steel |
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