CN111321273B - Method for accurately controlling alkalinity of 42CrMo steel refining slag - Google Patents
Method for accurately controlling alkalinity of 42CrMo steel refining slag Download PDFInfo
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- CN111321273B CN111321273B CN202010181735.4A CN202010181735A CN111321273B CN 111321273 B CN111321273 B CN 111321273B CN 202010181735 A CN202010181735 A CN 202010181735A CN 111321273 B CN111321273 B CN 111321273B
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- slag
- steel
- alkalinity
- electric furnace
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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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/54—Processes yielding slags of special composition
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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
- C21C7/0006—Adding metallic additives
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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
- C21C7/06—Deoxidising, e.g. killing
Abstract
The invention discloses a method for accurately controlling the alkalinity of 42CrMo steel refining slag, wherein the slag content in a steel belt is controlled to be 0-6 kg/t steel before electric furnace tapping; determining oxygen after the electric furnace smelting is finished; during the tapping process of the electric furnace, controlling the slag discharge amount of the electric furnace to be 1-5 kg/t steel; measuring the temperature and sampling after the ladle runs to an LF furnace, adding aluminum particles for diffusion deoxidation, and simultaneously adding 2-6 kg/t of steel lime and 0-3 kg/t of steel premelted refining slag to adjust the slag alkalinity and the total slag amount of the outbound slag; after white slag is formed, adding ferrochrome, ferromolybdenum, ferrosilicon and ferromanganese, keeping the white slag for more than or equal to 30min, and adjusting the aluminum content of molten steel by feeding an aluminum wire before the LF furnace is taken out of the station; the molten steel is taken out of the station after the component temperature meets the requirements, and the slag of the station is taken out for detection; the invention can realize the accurate control of the alkalinity of the 42CrMo steel refining slag, thereby fully playing the refining effect of the refining slag, greatly improving the control capability of the refining slag on the inclusion and improving the stability of the product quality.
Description
Technical Field
The invention belongs to the technical field of external refining, and particularly relates to a method for accurately controlling the alkalinity of 42CrMo steel refining slag.
Background
The 42CrMo steel for the wind power bearing belongs to alloy structural steel, has high-temperature creep strength and endurance strength, good low-temperature impact toughness and better hardenability, and has higher requirements on the types and grades of non-metallic inclusions in the steel. In order to improve the comprehensive quality of 42CrMo steel for wind power bearings, at present, steel-making enterprises generally adopt an external refining technology, and remove harmful elements and adsorbed inclusions in steel and control the shapes, types, quantities and sizes of the inclusions by adopting proper refining slag.
At present, two types of refining slag are mainly adopted at home and abroad to refine molten steel, one type is simple mixed type refining slag which is formed by mechanically mixing lime, bauxite and the like according to a certain proportion, the price is low, the production process is simple, but the melting point of slag is higher, the slagging process is slower, the components are unstable, and the refining effect is poorer; the other is premelted refining slag, which is prepared by mixing lime, bauxite and the like according to a certain proportion, performing electric melting, fully melting, cooling and crushing, and the premelted refining slag has a good refining effect.
No matter what kind of refining slag is adopted for refining, the core is to accurately control the components of the refining slag, especially the alkalinity of the refining slag, and a good refining effect can be achieved only by realizing the accurate control of the components of the refining slag, but no research report related to the alkalinity of 42CrMo steel refining slag is found at present.
Disclosure of Invention
The invention aims to provide a method for accurately controlling the alkalinity of 42CrMo steel refining slag, and aims to solve the problems that the alkalinity of the 42CrMo steel refining slag is not stably controlled and the refining effect is influenced in the prior art.
The technical scheme adopted by the invention is as follows:
a method for accurately controlling the alkalinity of 42CrMo steel refining slag comprises the following steps:
a. before electric furnace tapping, controlling the slag amount of a steel belt to be 0-6 kg/t steel; the influence of the slag amount in the final slag on the components of the final slag is accurately considered and evaluated, so that the accuracy and stability of each component in the final slag are improved;
b. after the electric furnace smelting is finished, oxygen is determined, when the electric furnace tapping quality reaches 1/3, 3-6 kg/t of steel aluminum iron is added into a ladle to ensure the stability of Al content in a refining station, and further, Al in slag is stably controlled2O3Content (c); when the tapping quality reaches 1/2, ferrosilicon and silicomanganese alloy are added to stabilize the yield of alloy elements such as Si, Mn and the like; when the steel tapping amount reaches 4/5, adding 5-8 kg/t of steel lime, and fully melting slag through strong stirring to shorten the slag forming time of refining;
c. during the tapping process of the electric furnace, controlling the slag discharge amount of the electric furnace to be 1-5 kg/t steel;the slag amount of the electric furnace is calculated by a rephosphorization formula: the amount of slag discharged from the electric furnace (total amount of rephosphorization-amount of rephosphorization in alloy) is the amount of molten steel discharged/amount of molten steel P in the electric furnace slag2O5The content is/0.564, and the stability of the control of the final slag component can be improved by accurately calculating the slag amount and fully considering the control of the final slag component;
wherein:
total phosphorus return-refined phosphorus content-electric furnace end point phosphorus content;
calculating the rephosphorization amount of the alloy according to the phosphorus content and the addition amount of the alloy;
the content of P2O5 in the electric furnace slag is measured by slag sample fluorescence analysis
d. In order to rapidly form slag, white slag is formed within 20 minutes, temperature measurement sampling is carried out after a ladle is operated to an LF furnace, 0.6-1.4 kg/t of steel aluminum particles are added for diffusion deoxidation, and simultaneously 2-6 kg/t of steel lime and 0-3 kg/t of pre-melted refining slag are added to adjust the slag alkalinity and the total slag amount of the outbound slag;
e. in order to improve LF treatment efficiency, stabilizing inclusion control level, adding ferrochromium, ferromolybdenum, ferrosilicon and ferromanganese after white slag is formed, keeping time of the white slag for more than or equal to 30min, and adjusting aluminum content of molten steel by feeding an aluminum wire before an LF furnace is taken out of a station;
f. and (4) taking out the molten steel after the component temperature of the molten steel meets the requirements, and taking out the slag of the station for detection.
Further, in the step b, the adding amount of the aluminum iron, the silicon iron and the silicon manganese alloy is 3.5-5.0 kg/t steel, 0.8-1.8 kg/t steel and 9-12 kg/t steel respectively.
In step b, the oxygen content is controlled to be 200-1000 ppm.
In the step c, the binary alkalinity of the slag as the slag discharging component of the electric furnace is 3-5, the mass fraction of FeO in the slag is 10-28%, and the mass fraction of MgO is 6.0-10.0%.
In the step d, the adding amount of the aluminum particles is 0.6-1.4 kg/t steel.
In the step e, the adding amount of the ferrosilicon and the ferromanganese is 0.3-0.5 kg/t steel and 1.0-2.0 kg/t steel respectively.
In the step f, the total slag amount of the outbound slag is 20-40 kg/t steel.
In the step f, the slag alkalinity of the outbound slag can be stably controlled to be 5.1-6.3.
The invention realizes the accurate control of the alkalinity of the 42CrMo steel refining slag by controlling the slag discharging amount and the components of the electric furnace, the slag quantity and the components of the ladle, the LF furnace slagging system and the like, thereby fully exerting the refining effect of the refining slag, greatly improving the control capability of the refining slag on the inclusion and improving the stability of the product quality.
Drawings
FIG. 1 is a comparison of slag basicity control in an example of the present invention and a conventional method.
Detailed Description
The present invention is further illustrated by the following specific examples.
The experiments were carried out on a 110 ton electric furnace and an LF furnace, comprising the following steps: controlling the slag amount of a ladle before electric furnace tapping, adding aluminum iron, silicon-manganese alloy and lime in the electric furnace tapping process, controlling the slag amount of the electric furnace, adding aluminum particles into an LF furnace, discharging the lime and premelted refining slag, and taking a slag sample from the LF furnace. Tables 1 to 4 show the key control parameters for the process according to the invention.
TABLE 1 control of the tapping process of an electric furnace
TABLE 2LF smelting Process control
TABLE 3 control of composition of tapped refining slag
TABLE 4 inclusion control
Compared with the traditional process, the method has the advantages that the alkalinity and inclusion control level of the refining slag are obviously improved, and the product quality stability is improved in the examples 1 to 9. After the method is adopted, the alkalinity fluctuation range of the refining slag is reduced from-0.4 to +3.2 to-0.4 to +0.8, the grade of the B-type inclusion is reduced from 1.5 to 0.5, the grade of the D-type inclusion is reduced from 1.0 to 0.5, and the grade of the Ds-type inclusion is stabilized below 0.5.
The above detailed description of a method for precisely controlling the basicity of 42CrMo steel refining slag with reference to the examples is illustrative and not restrictive, and several examples are cited within the limits thereof, so that variations and modifications thereof without departing from the general concept of the present invention shall fall within the scope of the present invention.
Claims (7)
1. The method for accurately controlling the alkalinity of 42CrMo steel refining slag is characterized by comprising the following steps of:
a. before tapping of the electric furnace, controlling the quantity of slag in a ladle belt which is less than 0 < 6 kg/t;
b. after the electric furnace smelting is finished, oxygen is determined, when the electric furnace tapping mass reaches 1/3, 3-6 kg/t of steel aluminum iron is added into a ladle, when the electric furnace tapping mass reaches 1/2, aluminum iron, silicon iron and silicon-manganese alloy are added, and when the tapping amount reaches 4/5, 5-8 kg/t of steel lime is added;
c. during the electric furnace tapping process, the electric furnace slag discharge amount is controlled, wherein the electric furnace slag discharge amount = (total phosphorus return amount-alloy phosphorus return amount) = tapping molten steel amount/P in electric furnace slag2O5Content/0.564;
d. measuring the temperature and sampling after the ladle runs to an LF furnace, adding aluminum particles for diffusion deoxidation, and simultaneously adding 2-6 kg/t of steel lime and 0-3 kg/t of steel premelted refining slag;
e. after white slag is formed, adding ferrochrome, ferromolybdenum, ferrosilicon and ferromanganese, keeping the white slag for more than or equal to 30min, and adjusting the aluminum content of molten steel by feeding an aluminum wire before the LF furnace is taken out of the station;
f. and (4) taking out the molten steel after the component temperature of the molten steel meets the requirements, and taking out the slag of the station for detection.
2. The method for precisely controlling the alkalinity of 42CrMo steel refining slag according to claim 1, wherein in the step b, the addition amounts of the aluminum iron, the silicon iron and the silicon manganese alloy are respectively 3.5-5.0 kg/t steel, 0.8-1.8 kg/t steel and 9-12 kg/t steel.
3. The method for accurately controlling the alkalinity of 42CrMo steel refining slag according to claim 1, wherein in step c, the binary alkalinity of slag as the slag component of the electric furnace is 3-5, the mass fraction of FeO in the slag is 10% -28%, and the mass fraction of MgO is 6.0% -10.0%.
4. The method for accurately controlling the alkalinity of 42CrMo steel refining slag according to claim 1, wherein in the step d, the adding amount of aluminum particles is 0.6-1.4 kg/t steel.
5. The method for accurately controlling the alkalinity of the 42CrMo steel refining slag according to claim 1, wherein in the step e, the addition amount of the ferrosilicon and the ferromanganese is 0.3-0.5 kg/t steel and 1.0-2.0 kg/t steel respectively.
6. The method for accurately controlling the alkalinity of 42CrMo steel refining slag according to claim 1, wherein in step f, the total slag amount of the outbound slag is 20-40 kg/t steel.
7. The method for accurately controlling the alkalinity of 42CrMo steel refining slag according to claim 1, wherein in the step f, the slag alkalinity of the outbound slag can be stably controlled within 5.1-6.3.
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Citations (5)
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|---|---|---|---|---|
| KR20100045053A (en) * | 2008-10-23 | 2010-05-03 | 주식회사 포스코 | Method for refining ferritic stainless steel containing titanium |
| CN102409238A (en) * | 2011-06-28 | 2012-04-11 | 南阳汉冶特钢有限公司 | 42CrMo alloy constructional steel super-thick plate and production method thereof |
| CN102643950A (en) * | 2011-02-18 | 2012-08-22 | 北大方正集团有限公司 | Method for smelting sulfur containing steel for vehicle and sulfur containing steel |
| CN105838846A (en) * | 2016-05-19 | 2016-08-10 | 山东钢铁股份有限公司 | Method for controlling basicity of LF refining slag |
| CN107299278A (en) * | 2017-06-01 | 2017-10-27 | 山东寿光巨能特钢有限公司 | A kind of resistance to ultralow temperature impact wind-powered electricity generation high-strength bolt steel making method |
-
2020
- 2020-03-16 CN CN202010181735.4A patent/CN111321273B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20100045053A (en) * | 2008-10-23 | 2010-05-03 | 주식회사 포스코 | Method for refining ferritic stainless steel containing titanium |
| CN102643950A (en) * | 2011-02-18 | 2012-08-22 | 北大方正集团有限公司 | Method for smelting sulfur containing steel for vehicle and sulfur containing steel |
| CN102409238A (en) * | 2011-06-28 | 2012-04-11 | 南阳汉冶特钢有限公司 | 42CrMo alloy constructional steel super-thick plate and production method thereof |
| CN105838846A (en) * | 2016-05-19 | 2016-08-10 | 山东钢铁股份有限公司 | Method for controlling basicity of LF refining slag |
| CN107299278A (en) * | 2017-06-01 | 2017-10-27 | 山东寿光巨能特钢有限公司 | A kind of resistance to ultralow temperature impact wind-powered electricity generation high-strength bolt steel making method |
Non-Patent Citations (1)
| Title |
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| 大方坯连铸42CrMoAH钢皮下夹杂物控制;庞聪等;《钢铁》;20131115(第11期);第50页 * |
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