CN113832381B - Refining process of high-purity GCr15SiMn bearing steel - Google Patents

Refining process of high-purity GCr15SiMn bearing steel Download PDF

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CN113832381B
CN113832381B CN202111138774.7A CN202111138774A CN113832381B CN 113832381 B CN113832381 B CN 113832381B CN 202111138774 A CN202111138774 A CN 202111138774A CN 113832381 B CN113832381 B CN 113832381B
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slag
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CN113832381A (en
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成国光
张国磊
王云鹏
王启明
李尧
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University of Science and Technology Beijing USTB
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/076—Use of slags or fluxes as treating agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
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Abstract

The invention discloses a refining process of GCr15SiMn bearing steel, which adopts a process route of 'EAF + slagging-off + LF + RH + die casting', and comprises the following specific contents: adding the Si-Fe alloy and a slag skimming agent in the EAF tapping process, and adding the Mn-Fe alloy and an LF synthetic slag refining agent to an LF station after ladle slag skimming; al is added in different working procedures in an optimized way, namely Al is not added in the EAF tapping process, and the Al content is controlled to be less than or equal to 0.003 percent; less Al is added in the LF process, and the content of the Al is controlled to be 0.005-0.008%; al is added in the RH degassing process, and the content of the Al is controlled to be 0.015 to 0.025 percent; and (4) after RH degassing is finished, calming the molten steel for 8-12 min. The content of O, Ti in the GCr15SiMn bearing steel produced by the invention can be controlled within 6ppm and 15ppm respectively, and the inclusion is fine, and the DS type inclusion is less than or equal to 0.5 grade.

Description

Refining process of high-purity GCr15SiMn bearing steel
Technical Field
The invention belongs to the technical field of production of high-quality high-carbon chromium bearing steel, and particularly relates to a refining process of GCr15SiMn bearing steel with low oxygen, low titanium and few inclusions.
Background
GCr15SiMn belongs to high-carbon chromium bearing steel, and comprises the following main components: 0.95-1.05% of C, 1.4-1.65% of Cr, 0.45-0.75% of Si and 0.95-1.25% of Mn, wherein the steel has better hardenability, wear resistance and elastic limit by improving Si and Mn alloy elements on the basis of GCr15 bearing steel, and is widely applied to the fields of wind power, heavy machinery, mining machinery and the like. In recent years, with the development of modern science and technology, higher and stricter requirements are put on the quality of bearing steel, and meanwhile, high-purity bearing steel is one of important tasks sought by metallurgy workers at present. The cleanliness of bearing steel is one of the most important factors influencing the fatigue life, and besides the influence of oxidation type inclusions, the harm of titanium-containing inclusions (such as TiN, Ti (CN) and the like) in the steel is very obvious, and the inclusions are angular and hard and seriously influence the fatigue life of the bearing steel. Therefore, the extra-high quality GCr15SiMn bearing steel is smelted, and the oxygen and titanium contents and the number of inclusions in the steel are controlled as necessary.
As the addition amount of Si-Fe, Mn-Fe and Cr-Fe alloy required by GCr15SiMn bearing steel is large, a plurality of technical difficulties are faced in the smelting process. The method mainly comprises the following three points: (1) large-particle inclusions of low-melting-point Si and Mn oxides are easy to appear, and once the inclusions are formed, the inclusions are difficult to remove in the subsequent process; (2) Si-Fe and Cr-Fe alloys have high residual Ti content and large use amount, so that the Ti content in molten steel is very difficult to reduce; (3) when Al is further added for deep deoxidation in the refining process, under the high-alkalinity slag refining process, Ti in the slag is easy to reduce and enter molten steel, Ca in CaO of the slag is easy to reduce and enter the molten steel, and low-melting-point calcium aluminate inclusion is formed, and the inclusion is not easy to remove and is very harmful to the fatigue life of steel.
In order to solve the above problems, the prior art includes: the addition of Al during tapping is a widely accepted method at present in order to reduce the formation of Si and Mn oxide inclusions. The addition of Al can play a role in deoxidation and reduction of large-particle inclusions of Si and Mn, but can also cause TiO in slag in the refining process2The reduction of the calcium aluminate slag causes the reduction of Ca in the slag, thereby forming calcium aluminate inclusions which are not beneficial to smelting low-titanium and high-cleanliness bearing steel; in order to reduce the content of Ti brought by the alloy, at present, each molten steel enterprise easily considers using the low-titanium alloy, however, the low-titanium iron alloy is expensive, and if the low-titanium alloy is completely adopted, the production cost is increased and the market competitiveness is reduced; in addition, in order to control the Ti content in the LF refining process, there have been proposed scholars that high-basicity slag is used for de-O with Al in the early stage of the LF refining and low-basicity slag is produced by adding silica in the late stage of the refining to control Ti, but adding silica in the late stage of the LF causes secondary pollution to the molten steel.
Disclosure of Invention
In order to meet the technical requirements of low oxygen, low titanium and high cleanliness in the smelting process of high-carbon chromium bearing steel, the invention provides a refining process of high-purity GCr15SiMn bearing steel. The process adopts a process route of 'EAF + slagging-off + LF + RH + die casting', and effectively reduces the O, Ti element and the quantity of inclusions in steel by strictly controlling the adding sequence of Si-Fe and Mn-Fe alloys, the optimized matching and adding of Al content among different working procedures, and optimizing a slagging-off agent, an LF furnace synthetic slag refining agent and the like in the smelting process, thereby providing technical support for producing high-quality special steel in China.
The specific refining process is that the raw material is refined,
in the process of the EAF, the raw materials are processed,
firstly adding Si-Fe alloy into a steel ladle in the tapping process, and then adding a certain amount of slag removing agent;
in the process of slag-off, the slag-off device,
carrying out slag skimming operation to control the slag skimming amount;
in the LF procedure, the process flow is,
firstly adding Mn-Fe alloy, then adding an LF synthetic slag refining agent, and after refining for a period of time, adding a certain amount of Al for deoxidation;
in the RH process, the reaction mixture is subjected to a reaction treatment,
reducing the vacuum pressure to a certain value, and adding a certain amount of Al to perform final deoxidation of the molten steel; and after RH degassing is finished, keeping the molten steel calm for a period of time to obtain the high-purity GCr15SiMn bearing steel.
Furthermore, the adding amount of Si-Fe alloy is added according to the lower limit required by GCr15SiMn steel alloy components in the tapping process, no Al is added, and the Al content is controlled to be less than or equal to 0.003 percent;
the addition amount of the slag removing agent is 2kg per ton of steel.
Further, in the slag skimming procedure, the slag skimming amount is controlled to be more than or equal to 90 percent.
Further, the slag remover comprises CaO and CaF2The weight ratio of the two is (3-5): 1, and the addition amount is 2 kg/ton steel.
Further, in the LF procedure, the addition amount of the LF synthetic slag refining agent is 8-10 kg per ton of steel;
in the LF refining process, 0.1-0.3 kg of Al is added into each ton of steel, so that the content of Al is controlled to be 0.005% -0.008%.
Further, the LF synthetic slag refining agent comprises the following components in percentage by mass: 50-60% CaO, 15-25% SiO2，10～20％Al2O3，5～10％CaF2，≤6％MgO，≤0.12％TiO2。
Furthermore, in the RH process, after the vacuum pressure is reduced to be less than or equal to 100Pa, 0.5-1.0 kg/ton of steel Al is added, and the content of Al is controlled to be 0.015-0.025 percent.
Further, the molten steel sedation time is 8-12 min.
Furthermore, the obtained high-purity GCr15SiMn bearing steel has O content less than or equal to 6ppm, Ti content less than or equal to 15ppm and inclusion DS less than or equal to 0.5 grade.
The GCr15SiMn bearing steel with high purity is obtained by refining the GCr15SiMn bearing steel by the process.
The technical principle of the invention is as follows:
(1) order of addition of Si-Fe, Mn-Fe alloys
Firstly, adding Si-Fe alloy according to the lower limit of the component requirement of steel during EAF tapping; secondly, slagging-off operation is adopted before the LF station, and the slagging-off amount of the steel ladle is required to be more than or equal to 90 percent; and adding Mn-Fe alloy after the ladle reaches the LF in place.
If the following steps are adopted in the process: firstly, Si-Fe and Mn-Fe alloys are added together during tapping or LF process, so that large inclusions of low-melting-point Si and Mn oxides are easily formed in molten steel, and once the inclusions are formed, the inclusions are difficult to remove; secondly, Mn-Fe alloy is added in the tapping process, Si-Fe alloy is added in the subsequent LF process, and because Si-Fe is higher than residual Ti content in Mn-Fe alloy, Ti element in the Si-Fe alloy cannot be removed by oxidation, and the content of Ti in molten steel is increased.
(2) Controlling the addition amount of Al between different processes
Firstly, EAF steel is tapped, Al is not added, the content of the Al is controlled to be less than or equal to 0.003 percent, and the content of Ti in the steel is easy to reduce in the subsequent working procedures; if Al is added in the process, the aim of reducing the content of Ti in steel is not easy to achieve;
secondly, in the LF refining process, 0.1-0.3 kg/ton of steel Al is added, the Al content is controlled to be 0.005% -0.008%, and the Al-Al refining process is used for reducing the oxygen content in steel and maintaining the Al-Al content between molten steel and slag in the refining process2O3And (4) balancing. If too much Al is added in the LF process, it will result in slagCa. Reducing Ti into molten steel;
finally, in the RH degassing process, when the vacuum pressure is reduced to 100Pa, 0.5-1.0 kg/ton of steel Al is added, the content of Al is controlled to be 0.015-0.025 percent, and the deep deoxidation of the molten steel is carried out; meanwhile, because the molten steel and the slag do not react basically in the RH degassing process, the risk of generating inclusions due to the reaction of Al and the slag can be greatly reduced.
(3) Optimized slag skimming agent in EAF tapping process
The slag skimming agent comprises CaO and CaF2The weight ratio of the two is preferably (3-5): 1, the addition amount is 2 kg/ton steel, and the catalyst is mainly used for removing TiO generated after the Si-Fe alloy is added2And the like acidic inclusions.
If added according to other components, the ladle slag is too dry or too dilute; if no or little slag skimming agent is added in the tapping process, ladle scum is not easy to skimming in the subsequent slag skimming operation process.
(4) Adding optimized synthetic slag refining agent after LF is in place
The synthetic slag refining agent comprises 50-60% of CaO and 15-25% of SiO2，10～20％Al2O3，5～10％CaF2，≤6％MgO，≤0.12％TiO2The addition amount is 8-10 kg per ton steel.
If other synthetic slag refining agent components are selected, the content of Ti in steel is increased, the fluidity of slag is poor, and more calcium aluminate inclusions are generated.
(5) In order to prevent secondary pollution of molten steel, after RH degassing is finished, the molten steel is kept calmed for 10min, and bottom blowing soft stirring of a ladle is cancelled.
Compared with the prior art, the process has the beneficial effects of smelting high-purity bearing steel:
(1) less Al is added in the LF refining process, and preliminary deoxidation of molten steel is carried out; in the RH process, Al is added for deep deoxidation, so that the O content in the final steel product can be reduced to 6 ppm.
(2) The invention controls TiO in the slag through full flow2Reducing the Ti content in the GCr15SiMn steel to 15 ppm. The specific method comprises the following steps: firstly, bySlag "working out" to prevent higher TiO content2The slag enters LF refining slag; ② less Al is added in the LF refining process, TiO in Al reduction furnace slag is avoided2(ii) a Thirdly, by utilizing the characteristic that the molten steel of the RH furnace does not react with the furnace slag, TiO in the furnace slag can be prevented2Reduction of (2).
(3) The high-purity bearing steel produced by the method has fine inclusions and DS less than or equal to 0.5 grade. The method specifically comprises the following steps: Si-Fe and Mn-Fe alloys are added separately, so that large-particle inclusions of low-melting-point Si and Mn oxides in molten steel can be avoided; al is selected to be added in the RH process, so that Ca and Si in the reduction furnace slag are prevented from entering molten steel to form calcium aluminate and silicate inclusions; and thirdly, after RH is finished, bottom blowing soft stirring is cancelled, and generation of impurities can be reduced.
(4) The invention reduces the requirement of the Si-Fe alloy on the Ti content and saves the cost of raw and auxiliary materials.
Drawings
FIG. 1 is a flow chart of a refining process of high purity GCr15SiMn bearing steel of the present invention.
FIG. 2 is a schematic diagram of typical inclusion composition, size and morphology of GCr15SiMn bearing steel according to an embodiment of the present invention.
FIG. 3 shows CaAl of large particles in comparative example2O4The size and the appearance of the inclusions of the class and the Si-Mn oxide class are shown schematically.
Detailed Description
The process of the present invention will be described in detail with reference to specific embodiments in order to better understand the technical problems, technical solutions and advantages to be solved by the present invention for those skilled in the art.
As shown in figure 1, the refining process of the high-purity GCr15SiMn bearing steel adopts a process route of 'EAF + slagging-off + LF + RH + pouring', and further controls: the addition sequence of Si-Fe and Mn-Fe alloys, the collocation of Al in different working procedures, the preferable addition of a slag skimming agent and a synthetic slag refining agent and the like can effectively reduce the O, Ti content in steel and the number of inclusions.
(1) The EAF process comprises the following steps:
when the content of C in the molten steel meets the end point and is 0.1-0.3%, and the temperature is 1620-1660 ℃, tapping;
adding 6-7 kg/ton steel Si-Fe alloy and other alloys in the tapping process;
after the alloy is added, 2 kg/ton steel slag skimming agent is added, and CaO: CaF in the selected slag skimming agent2The weight ratio is 4: 1;
(2) the slag skimming process comprises the following steps:
the ladle reaches a slag skimming station, more than 90 percent of slag above the ladle is removed by using a slag skimming machine, and excessive TiO in the slag is avoided2The process proceeds to the LF process.
(3) The LF furnace refining process comprises the following steps:
after the steel ladle reaches an LF station, adding 8-9.5 kg/ton steel Mn-Fe alloy;
after the alloy is added, adding a pre-prepared synthetic slag refining agent of 8-10 kg/ton steel;
and refining for 20-30 min until the content of LF slag reaches CaO: 50-60% of SiO2：15～25％，Al2O3：10～20％，CaF2: 5-10%, MgO: less than or equal to 6 percent, and maintaining the refining slag components until the LF is finished, and discharging.
(4) The degassing process of the RH furnace comprises the following steps:
when the vacuum pressure is reduced to be less than or equal to 100Pa, 0.5-1.0 kg/ton of steel Al alloy is added; and (5) breaking the air after keeping the ultimate vacuum for 25-35 min.
And after RH degassing is finished, closing an argon blowing valve, and keeping for 10min, wherein when the temperature of the molten steel is 1500-1530 ℃, the ladle is hung.
(5) The die casting process comprises the following steps:
and when die casting pouring is adopted, argon is blown in the whole process for protective pouring.
The process is suitable for smelting GCr15SiMn bearing steel and similar bearing steel or special steel varieties with similar quality requirements.
Example 1
The GCr15SiMn bearing steel with low oxygen, low titanium and few inclusions can be smelted by adopting the production process flow of 'EAF + slagging-off + LF + RH + die casting'.
(1) EAF primary refining: when the smelting is finished, the temperature is 1658 ℃, and the molten steel comprises the following components: [C] 0.19%, [ Si ] 0.01%, [ Mn ] 0.21%, [ Al ] 0.003%, and a tap quantity of 129.5 t;
in the tapping process, 6.5 kg/ton steel Si-Fe alloy (Ti content is 0.05 percent) is added, and Cr-Fe and other alloys are added according to the component design requirements of steel types; then 1.6 kg/ton steel lime, 0.4 kg/ton steel CaF are added2(ii) a At the moment, Al is not added, so that TiO in the slag is avoided2Reduction of (2).
(2) Slag skimming operation: and after tapping, conveying the steel ladle filled with the molten steel to a slag removing station, and removing slag above the steel ladle by using a slag removing machine, wherein the removing amount is about 95%.
(3) LF refining: when the steel ladle is in place, 8.5 kg/ton steel metal manganese (the content of Ti is 0.015 percent) and 9 kg/ton steel synthetic slag refining agent are sequentially added into the molten steel. And (3) after refining for 25min, measuring the temperature, sampling and delivering samples, wherein the steel sample composition detected after 10min is as follows: [ C ]]0.78％，[Si]0.47％，[Mn]1.11 percent. Adding 0.2 kg/ton steel Al, finely adjusting the alloy, transmitting electricity for 15min, measuring the temperature, and taking an LF middle-stage sample; the steel sample detected after 10min comprises the following components: [ C ]]0.97％，[Si]0.56％，[Mn]1.10％，[Al]0.006%, the slag composition of which is CaO: 54.4% of SiO2：18.1％，Al2O3：13.3％，CaF2: 5.8%, MgO: 4.1 percent; maintaining the slag components for 40min, measuring temperature, and taking out.
(4) RH degassing: starting a vacuum pump to pump air for 6min after the RH station enters, reducing the pressure to 100Pa, and then adding 0.9 kg/ton of steel Al for final deoxidation; after refining for 10min, measuring the temperature, sampling and delivering samples to obtain 0.020% of [ Al ] in the molten steel; and after continuously maintaining the vacuum for 15min, breaking the vacuum. After RH is finished, after the molten steel is calmed for 10min, the temperature is measured at 1510 ℃, and the steel is taken out of the station.
(5) Die casting pouring: and after the ladle arrives at the station, introducing argon gas between the pouring nozzle and the middle pouring pipe for protective pouring, wherein the pouring temperature is 1490 ℃.
The contents of O and Ti in the GCr15SiMn bearing steel material smelted by the method are 5.5ppm and 14ppm respectively, the inclusions are fine, and the DS type inclusions are less than or equal to 0.5 grade (shown in figure 2).
Example 2
And the GCr15SiMn bearing steel is produced by adopting the production process flow of 'EAF + slagging-off + LF + RH + die casting'.
(1) EAF primary refining: when the smelting is finished, the temperature is 1650 ℃, and the molten steel comprises the following components: [C] 0.16%, [ Si ] 0.01%, [ Mn ] 0.15%, [ Al ] 0.002%, and a tap amount of 130 t;
in the tapping process, 6.5 kg/ton steel Si-Fe alloy is added, and Cr-Fe and other alloys are added according to the component design requirements of steel types; then 1.5 kg/ton steel lime and 0.5 kg/ton steel CaF are added2。
(2) Slag skimming operation: the operation was substantially the same as in example 1, and the slag removal amount was about 92%.
(3) LF refining: and (3) putting the steel ladle in place, and sequentially adding 8.8 kg/ton of steel metal manganese and 9 kg/ton of steel synthetic slag refining agent into the molten steel. And (3) after refining for 25min, measuring the temperature, sampling and delivering samples, wherein the steel sample composition detected after 10min is as follows: [ C ]]0.96％，[Si]0.52％，[Mn]1.01 percent. Adding 0.25 kg/ton steel Al, finely adjusting the alloy, transmitting electricity for 15min, measuring the temperature, and taking an LF middle-stage sample; the components of the steel sample detected after 10min are as follows: [ C ]]0.98％，[Si]0.55％，[Mn]1.10％，[Al]0.008% and slag components of CaO: 53.4% of SiO2：18.5％，Al2O3：13.5％，CaF2: 5.3%, MgO: 4.7 percent; maintaining the slag components for 45min, measuring temperature, and taking out.
(4) RH degassing: starting a vacuum pump to pump air after the RH station enters, reducing the pressure to 95Pa, and adding 0.8 kg/ton of steel Al; refining for 10min, measuring temperature, sampling and delivering samples to obtain 0.018 percent of [ Al ] in the molten steel; after keeping the extreme vacuum for 15min, breaking the air. After RH is finished, after molten steel is calmed for 10min, temperature is measured, and the steel is taken out of the station.
(5) Die casting pouring: the operation is substantially the same as in example 1.
The GCr15SiMn bearing steel material smelted in the embodiment has the O content and the Ti content of 6.0ppm and 15ppm respectively, and the inclusions are fine.
Example 3
And the GCr15SiMn bearing steel is produced by adopting the production process flow of 'EAF + slagging-off + LF + RH + die casting'.
(1) EAF primary refining: when the smelting is finished, the temperature is 1658 ℃, and the molten steel comprises the following components: [C] 0.22%, [ Si ] 0.02%, [ Mn ] 0.20%, [ Al ] 0.003%, and a tap-off amount of 130 t;
during tapping, 6.4 kg/ton steel Si-Fe alloy and other alloys are added; then 1.6 kg/ton steel lime and 0.4 kg/ton steel CaF are added2。
(2) Slag skimming operation: the operation is substantially the same as in example 1.
(3) LF refining: and (3) putting the steel ladle in place, and sequentially adding 8.5 kg/ton of steel metal manganese and 9.5 kg/ton of steel synthetic slag refining agent into the molten steel. And (3) after refining for 22min, measuring the temperature, sampling and delivering samples, wherein the steel sample components detected after 10min are as follows: [ C ]]0.88％，[Si]0.57％，[Mn]1.05 percent. Adding 0.2 kg/ton steel Al, finely adjusting the alloy, transmitting electricity for 15min, measuring the temperature, and taking an LF middle-stage sample; the components of the steel sample detected after 10min are as follows: [ C ]]0.98％，[Si]0.56％，[Mn]1.08％，[Al]0.007%, and the slag component is CaO: 56.5% of SiO2：16.2％，Al2O3：14.6％，CaF2: 5.5%, MgO: 4.2 percent; maintaining the slag components for 43min, measuring temperature, and taking out.
(4) RH degassing: after the RH station enters, when the vacuum pressure is reduced to 100Pa, 0.85 kg/ton of steel Al is added; after refining for 10min, sampling and feeding to obtain 0.020% of Al in the molten steel; and after the vacuum is continuously kept for 18min, the vacuum is broken. After RH is finished, after molten steel is calmed for 12min, temperature is measured, and the steel is taken out of the station.
(5) Die casting pouring: the operation is substantially the same as in example 1.
The content of O, Ti in the GCr15SiMn bearing steel material smelted by the method is 5.8ppm and 14ppm respectively, the inclusion is fine, and the DS type inclusion is less than or equal to 0.5 grade.
Comparative example
The low-oxygen and low-titanium GCr15SiMn bearing steel is smelted by adopting a production process flow of 'EAF + LF + VD + weak stirring + die casting'.
(1) EAF primary refining: the operation is basically the same as the embodiment, when the smelting is finished, the temperature is 1648 ℃, the terminal point [ C ] is 0.18 percent, and the steel tapping amount is 130 t. The main differences from the examples are:
during tapping, 6.5 kg/ton steel Si-Fe, 8.5 kg/ton steel Mn-Fe and other alloys were added.
(2) LF refining: adding LF slagging refining agent (refining agent components: CaO 55-65%, SiO)2：10～20％，Al2O3: 15-25%, MgO: less than or equal to 6 percent). And (3) after refining for 25min, measuring the temperature, sampling and delivering samples, wherein the steel sample components detected after 10min are as follows: [ C ]]0.85％，[Si]0.55％，[Mn]1.04 percent. Adding 1.2 kg/ton steel Al, finely adjusting the alloy, transmitting electricity for 15min, measuring the temperature, and taking an LF middle-stage sample; the components of the steel sample detected after 10min are as follows: [ C ]]0.97％，[Si]0.56％，[Mn]1.10％，[Al]0.035%, the slag composition is CaO: 60.4% of SiO2：13.1％，Al2O3: 18.3%, MgO: 4.1 percent; maintaining the slag components for 40min, measuring temperature, and taking out.
(3) VD degassing: after vacuumizing for 10min, when the vacuum degree is reduced to below 67Pa and kept stable, the argon blowing flow is adjusted to be 1-2 NL/min/ton of steel, and after the ultimate vacuum is kept for 20min, the vacuum is broken.
(4) Stirring with weak argon: after the reaction is completed, 40kg of covering agent is added for heat preservation treatment, argon flow is blown in for 60NL/min for weak argon stirring, after stirring for 30min, the temperature is measured at 1500 ℃, and the bag is hung.
(5) Die casting pouring: the operation is substantially the same as in example 1.
The contents of O and Ti in the GCr15SiMn bearing steel material smelted by the comparative example are 8.5ppm and 28ppm respectively, and obvious CaAl exists in the final bearing steel finished product2O4Large-particle inclusions of the group and Si-Mn oxide group (see FIG. 3).
The refining process of the high-purity GCr15SiMn bearing steel provided by the embodiment of the application is described in detail above. The above description of the embodiments is only for the purpose of helping to understand the method of the present application and its core ideas; meanwhile, for a person skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.
As used in the specification and claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. The present specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, that a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect. The following description is of the preferred embodiment for carrying out the present application, but is made for the purpose of illustrating the general principles of the application and is not to be taken in a limiting sense. The protection scope of the present application shall be subject to the definitions of the appended claims.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a commodity or system that includes the element.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter associated objects are in an "or" relationship.
The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the application as described herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.

Claims (7)

1. A refining process of high-purity GCr15SiMn bearing steel comprises the following working procedures: EAF + slagging-off + LF + RH + die casting, which is characterized in that,
in the EAF procedure, firstly adding Si-Fe alloy into a ladle in the tapping process, and then adding a certain amount of slag removing agent;
adding Si-Fe alloy in the EAF tapping process, wherein no Al is added, and controlling the Al content to be less than or equal to 0.003%;
the addition amount of the slag skimming agent is 2 kg/ton steel
In the slag skimming procedure, the slag skimming operation is carried out, and the slag skimming amount is controlled;
in the LF procedure, after Mn-Fe alloy is added, an LF synthetic slag refining agent is added, and after a period of refining, a certain amount of Al is added for deoxidation;
the addition amount of the LF synthetic slag refining agent is 8-10 kg per ton of steel;
in the LF refining process, 0.1-0.3 kg of Al is added per ton of steel, and the content of Al is controlled to be 0.005% -0.008%;
in the RH process, when the vacuum pressure is reduced to a certain value, a certain amount of Al is added for final deoxidation; and after RH degassing is finished, keeping the molten steel calmed for a period of time to obtain the high-purity GCr15SiMn bearing steel, wherein the O content in the obtained high-purity GCr15SiMn bearing steel is less than or equal to 6ppm, the Ti content is less than or equal to 15ppm, and the DS of inclusions is less than or equal to 0.5 grade.
2. The refining process according to claim 1, wherein the slag skimming amount is not less than 90% in the slag skimming process.
3. The refining process according to claim 2, wherein the slag remover comprises CaO and CaF2 in a weight ratio of (3-5) to 1.
4. The refining process of claim 1, wherein the LF synthetic slag refining agent comprises the following components in percentage by mass: 50-60% of CaO and 15-25%SiO2，10～20％Al2O3，5～10％CaF2，≤6％MgO，≤0 .12％TiO2。
5. A refining process according to claim 1, wherein in the RH process, after the vacuum pressure is reduced to 100Pa or less, the amount of Al added is 0.5 to 1.0 kg/ton of steel, and the Al content is controlled to 0.015 to 0.025%.
6. The refining process according to claim 1, wherein the molten steel is killed for 8-12 min.
7. A GCr15SiMn bearing steel of high purity, characterized in that the GCr15SiMn bearing steel is obtained by the refining process according to any one of claims 1 to 6.
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