CN110643786A - Production process for improving purity of bearing steel - Google Patents
Production process for improving purity of bearing steel Download PDFInfo
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- CN110643786A CN110643786A CN201910717568.8A CN201910717568A CN110643786A CN 110643786 A CN110643786 A CN 110643786A CN 201910717568 A CN201910717568 A CN 201910717568A CN 110643786 A CN110643786 A CN 110643786A
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- 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
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- 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
- C21C7/072—Treatment with gases
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- 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
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- 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
- Y02P10/20—Recycling
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Abstract
The invention discloses a production process for improving the purity of bearing steel, which comprises the working procedures of smelting, LF refining, VD vacuum treatment and casting, wherein the working procedure of the LF refining comprises the following steps: adopting high-aluminum refining slag; bottom blowing argon gas at 100-150 NL/min in the early stage of refining, bottom blowing argon gas at 300-350 NL/min in the middle stage of refining, and bottom blowing argon gas at 150-200 NL/min in the later stage of refining; the VD vacuum treatment process comprises the following steps: standing for 15-20 min after VD soft blowing is finished; the casting process comprises the following steps: the bottom of the ladle nozzle is provided with a spherical structure. The process improves the purity of the bearing steel by using high-aluminum refining slag, optimizing a bottom argon blowing system in the LF refining process, increasing a static deoxidation technology by VD (vacuum distillation), and adopting a spherical nozzle protection pouring technology in ladle pouring; the obtained bearing steel has low oxygen content, less and fine inclusions, and meets the performance requirements of high-end bearing steel.
Description
Technical Field
The invention belongs to the technical field of steel industrial production, and particularly relates to a production process for improving the purity of bearing steel.
Background
The high-carbon chromium bearing steel GCr15 with high hardness, good wear resistance, uniform properties and high elastic limit is a representative steel grade called 'King of steel' bearing steel and is used for manufacturing balls, rollers and shaft ring sleeves. Has strict requirements on oxygen content, inclusion and the like.
Since the nonmetallic inclusions tend to cause stress concentration, the nonmetallic inclusions in the bearing steel become a fatigue crack source, and the fatigue life of the bearing steel is reduced. The method reduces the number of inclusions in steel and controls the size of the inclusions, and is a main way for improving the quality of bearing steel and prolonging the service life of a bearing. The non-metallic inclusions in the bearing steel are mainly oxides, so the oxygen content of the bearing steel is an important index for measuring the quality of the steel. In view of the above, in order to improve the quality and life of bearing steel, the oxygen content in the steel is controlled, and the number and size of inclusions in the steel are controlled. The bearing produced by the traditional process has high oxygen content and prominent oversized inclusions, and the quality of the bearing steel and the service life of the bearing are seriously influenced.
Disclosure of Invention
The invention aims to provide a production process for improving the purity of bearing steel, which is suitable for high-carbon chromium bearing steel so as to improve the quality of the bearing steel.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the method comprises the working procedures of smelting, LF refining, VD vacuum treatment and casting, and is characterized in that the working procedure of LF refining is as follows: adopting high-aluminum refining slag; bottom blowing argon gas at 100-150 NL/min in the early stage of refining, bottom blowing argon gas at 300-350 NL/min in the middle stage of refining, and bottom blowing argon gas at 150-200 NL/min in the later stage of refining;
the VD vacuum treatment process comprises the following steps: standing for 15-20 min after VD soft blowing is finished;
the casting process comprises the following steps: the bottom of the ladle nozzle is provided with a spherical structure.
The high-aluminum refining slag comprises the following main components in percentage by mass: 45-55% of CaO and SiO2 7~12%，Al2O325-36%, and the balance: 0.1-0.5% of FeO, 4-8% of MgO, less than or equal to 0.28% of TiO, less than or equal to 0.49% of MnO, and P2O5 ≤0.028%，S ≤1.2%，CaF2≤1.4%。
The basicity R =4.0 ~ 7.9.9 of the high-aluminum refining slag is disclosed.
The refining time in the early stage is 5-15 min, the refining time in the middle stage is 30-35 min, and the refining time in the later stage is 15-20 min.
The contact surface of the bottom of the ladle nozzle and the long nozzle is of a spherical structure, and the height of the contact surface matched with the bottom of the ladle nozzle and the long nozzle is 20-40 mm. Thus, a large gap on the contact surface side is eliminated, the sealing effect is good, and secondary oxidation of molten steel is reduced.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: according to the invention, the high-aluminum refining slag is used, the bottom argon blowing system in the LF refining process is optimized, the VD (vacuum degassing) is added with a standing deoxidation technology, and the ladle casting adopts a spherical nozzle protection casting technology, so that the purity of the bearing steel is improved; the obtained bearing steel has low oxygen content and small and fine inclusion, meets the performance requirements of high-end bearing steel, and is particularly suitable for high-carbon chromium bearing steel such as GCr15 series, SUJ2, C & U1, 52100S 300 and the like.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
Example 1: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 46%, SiO2 9.7%，Al2O336%, and the balance: FeO 0.16%, MgO 8%, TiO 0.04%, MnO 0.07%, P2O5 0，S 0，CaF2 0.03%, basicity R = 4.7.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the early stage of refining is 6min, and argon gas is blown at the bottom for 60 NL/min; the duration of the middle period of refining is 30min, and argon gas is blown from the bottom to the position of 305 NL/min; the time length of the later period of the refining is 15.5min, and the argon gas is blown at the bottom for 155 NL/min.
(2) VD vacuum treatment process: and standing for 15.5min after VD soft blowing is finished so as to enable inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 22mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the molten steel is reduced to be sucked in the pouring process of the long nozzle, so that the secondary.
Example 2: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 45%, SiO2 11.3%，Al2O335 percent, and the rest components: 0.1% of FeO, 8% of MgO, 0.08% of TiO, 0.21% of MnO, 0.16% of P2O 50, 20.2% of CaF20, and the alkalinity R = 4.0.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the early stage of refining is 5min, and the bottom blowing argon gas is 105 NL/min; the duration of the middle period of refining is 30.5min, and the bottom blowing argon gas is 300 NL/min; the time length of the later period of refining is 16min, and the bottom blowing argon gas is 160 NL/min.
(2) VD vacuum treatment process: and after VD soft blowing is finished, standing for 16min to enable the inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 24mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the molten steel is reduced to be sucked in the pouring process of the long nozzle, so that the secondary.
Example 3: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 48%, SiO2 9.0%，Al2O335 percent, and the rest components: FeO 0.22%, MgO 7.2%, TiO 0, MnO 0.23%, P2O5 0.01%，S 0.34%，CaF2 0, basicity R = 5.3.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the early stage of refining is 11min, and argon gas is blown at the bottom for 110 NL/min; the duration of the middle period of refining is 31min, and the bottom blowing argon gas is 310 NL/min; the time length of the later period of refining is 15min, and the bottom blowing argon gas is 150 NL/min.
(2) VD vacuum treatment process: and after VD soft blowing is finished, standing for 16.5min to enable inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle is added with a spherical structure with the height of 20mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surface of the ladle nozzle and the long nozzle can still be kept in line contact, and the molten steel suction is reduced in the long nozzle pouring process, so that the secondary oxidation is reduced.
Example 4: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 50%, SiO2 8%，Al2O334 percent, and the rest components: FeO 0.28%, MgO 5.8%, TiO 0.2%, MnO 0, P2O5 0.01%，S 0.51%，CaF2 1.2% and basicity R = 6.3.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the refining earlier stage is 8min, and the bottom blowing argon is 100 NL/min; the duration of the middle period of refining is 32min, and the bottom blowing argon gas is 320 NL/min; the time length of the later period of the refining is 17min, and the argon gas is blown at the bottom for 170 NL/min.
(2) VD vacuum treatment process: and standing for 15min after VD soft blowing is finished so as to enable inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 28mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the molten steel is reduced to be sucked in the pouring process of the long nozzle, so that the secondary.
Example 5: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 52%, SiO2 10.5%，Al2O329%, and the balance: FeO 0.34%, MgO 6.01%, TiO 0.16%, MnO 0.49%, P2O5 0.02%，S 0.68%，CaF2 0.8%, basicity R = 5.0.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the refining earlier stage is 15min, and the bottom blowing argon gas is 135 NL/min; the duration of the middle period of refining is 33.5min, and argon gas is blown at the bottom of the refining at 335 NL/min; the time length of the later period of refining is 18.5min, and the argon gas is blown to the bottom at 200 NL/min.
(2) VD vacuum treatment process: and standing for 18.5min after VD soft blowing is finished so as to enable inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 34mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the suction of molten steel is reduced in the pouring process of the long nozzle, so that the secondary oxidation is.
Example 6: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 54%, SiO2 11%，Al2O325%, and the balance: FeO 0.4%, MgO 7%, TiO 0.28%, MnO 0.35%, P2O5 0.02%，S 0.55%，CaF2 1.4%, basicity R = 4.9.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the refining earlier stage is 12min, and the bottom blowing argon is 150 NL/min; the duration of the middle period of refining is 34min, and argon gas is blown from the bottom to 340 NL/min; the time length of the later period of refining is 20min, and the bottom blowing argon is 185 NL/min.
(2) VD vacuum treatment process: and after VD soft blowing is finished, standing for 19min to enable the inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 36mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the molten steel is reduced to be sucked in the pouring process of the long nozzle, so that the secondary.
Example 7: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 54%, SiO2 12%，Al2O327%, and the balance: FeO 0.44%, MgO 4%, TiO 0.24%, MnO 0.42%, P2O5 0.02%，S 1.2%，CaF2 0.68% and basicity R = 4.5.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the early stage of refining is 13min, and argon is blown from the bottom at 140 NL/min; the duration of the middle period of refining is 34.5min, and the bottom blowing argon is 350 NL/min; the time length of the later period of the refining is 19min, and the argon gas is blown at the bottom of 190 NL/min.
(2) VD vacuum treatment process: and after VD soft blowing is finished, standing for 19.5min to enable inclusions to float up naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 40mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the molten steel is reduced to be sucked in the pouring process of the long nozzle, so that the secondary.
Example 8: the production process for improving the purity of the bearing steel is specifically described as follows.
(1) An LF refining procedure: the high-aluminum refining slag comprises the following components in parts by weight: CaO 55%, SiO2 7%，Al2O327%, and the balance: FeO 0.5%, MgO 7.6%, TiO 0.2%, MnO 0.28%, P2O5 0.03%，S 1.12%，CaF2 1.27%, basicity R = 7.9.
The bottom blowing argon amount in the refining process adopts a small-large-small mode: the time length of the early stage of refining is 14min, and argon gas is blown from the bottom to 145 NL/min; the duration of the middle period of refining is 35min, and argon is blown from the bottom to 345 NL/min; the time length of the later period of the refining is 19.5min, and argon gas is blown at the bottom of 195 NL/min.
(2) VD vacuum treatment process: and standing for 20min after VD soft blowing is finished so as to enable inclusions to float naturally.
(3) A casting process: the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, the height of the contact surfaces matched with the bottom of the ladle nozzle and the contact surface of the long nozzle is 38mm, the spherical diameter is the outer diameter of the lower end of the ladle nozzle, when the long nozzle is poured in the tilting process (the inclination angle is less than 10 degrees), the contact surfaces of the ladle nozzle and the long nozzle can still be kept in line contact, and the suction of molten steel is reduced in the pouring process of the long nozzle, so that the secondary oxidation is.
And (3) performance testing: three types of commercially available bearing steels were used as a control group and the three types of bearing steels obtained in examples 1 to 3 were subjected to test analysis including oxygen content and inclusions, and the test analysis methods were as follows.
The bearing steels 1 to 3 on the market are GCr15, SUJ2 and C & U1 respectively, and the steel grades of examples 1 to 8 are as follows: GCr15, SUJ2, C & U1, GCr15-JN, GCr15-SK, 52100S 300, SUJ2 and C & U1.
(1) The oxygen content detection method comprises the following steps: the test material was prepared as a standard oxygen-nitrogen analysis sample, and the oxygen content in steel was measured by an oxygen-nitrogen-hydrogen analyzer, and the results are shown in table 1.
Table 1: oxygen content test results of examples and controls
(2) The method for analyzing inclusions in steel comprises the following steps: the experimental material was made into a standard inclusion analysis sample, the number of inclusions in steel was analyzed by a metallographic microscope and rated, and the test results are shown in table 2.
Table 2: results of analysis of inclusions in examples and control groups
The detection and analysis results show that the bearing steel produced by the production process has high purity, low oxygen content and fine inclusions.
Claims (6)
1. The production process for improving the purity of the bearing steel comprises the working procedures of smelting, LF refining, VD vacuum treatment and casting, and is characterized in that the working procedure of LF refining is as follows: adopting high-aluminum refining slag; bottom blowing argon gas at 100-150 NL/min in the early stage of refining, bottom blowing argon gas at 300-350 NL/min in the middle stage of refining, and bottom blowing argon gas at 150-200 NL/min in the later stage of refining;
the VD vacuum treatment process comprises the following steps: standing for 15-20 min after VD soft blowing is finished;
the casting process comprises the following steps: the bottom of the ladle nozzle is provided with a spherical structure.
2. The production process for improving the purity of the bearing steel according to claim 1, which is characterized in that: the high-aluminum refining slagThe main components in the composition comprise the following components in percentage by mass: 45-55% of CaO and SiO2 7~12%，Al2O325-36%, and the balance: 0.1-0.5% of FeO, 4-8% of MgO, less than or equal to 0.28% of TiO, less than or equal to 0.49% of MnO, and P2O5 ≤0.028%，S ≤1.2%，CaF2≤1.4%。
3. The production process for improving the purity of bearing steel according to claim 2, wherein the basicity of the high-aluminum refining slag is R =4.0 ~ 7.9.9.
4. A process according to claim 1, 2 or 3 for producing a bearing steel with improved purity, wherein: the time of the early stage of refining is 5-15 min, the time of the middle stage of refining is 30-35 min, and the time of the later stage of refining is 15-20 min.
5. A process according to claim 1, 2 or 3 for producing a bearing steel with improved purity, wherein: the bottom of the ladle nozzle is additionally provided with a spherical structure with the height of 20-40 mm, and the spherical diameter is the outer diameter of the lower end of the ladle nozzle.
6. The production process for improving the purity of the bearing steel according to claim 4, wherein the production process comprises the following steps: the contact surface of the bottom of the ladle nozzle and the contact surface of the long nozzle are of spherical structures, and the height of the contact surfaces matched with the bottom of the ladle nozzle and the height of the contact surfaces is 20-40 mm.
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Application publication date: 20200103 |