CN113088797A - Shallow treatment process suitable for SPHC low-carbon series steel grades - Google Patents
Shallow treatment process suitable for SPHC low-carbon series steel grades Download PDFInfo
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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
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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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
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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
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—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
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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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
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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
- C21C7/064—Dephosphorising; Desulfurising
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Abstract
The invention belongs to the technical field of steel smelting, and particularly relates to a shallow treatment process suitable for SPHC low-carbon series steel grades. According to the shallow treatment process suitable for the SPHC low-carbon series steel grade, the content of acid-soluble aluminum is controlled through the control of the terminal point components and the temperature of the converter and the control of the content of acid-soluble aluminum in the deoxidation alloying stage of the tapping of the converter, so that the molten steel peroxidation in the steelmaking of the converter is reduced or avoided; and the synthetic slag is added in the tapping process, and the deoxidation accelerant is added at the same time, so that the slag sample components and the proportion are effectively blended, the converter final slag directly forms yellow white slag, the slag melting and slagging are not needed in the LF refining stage, the LF refining step is simplified, the LF refining time is shortened, the productivity of the LF refining furnace is released, in addition, the power consumption and the addition amount of the deoxidizer in the LF refining stage are reduced, and the cost and the energy consumption are reduced.
Description
Technical Field
The invention relates to the technical field of steel smelting, in particular to a shallow treatment process suitable for SPHC low-carbon series steel grades.
Background
When a steel mill adopts a BOF-LF-CC process route to smelt low-carbon series steel grades such as SPHC and the like, synthetic slag is added for slag washing when a converter discharges steel, and after molten steel reaches a refining furnace, refining operators perform temperature raising, component fine adjustment, slag formation and the like according to the temperature, components, slag conditions and the like of the incoming molten steel. Because of the factors of the operation level of stokehole personnel, the steel discharging temperature and the steel discharging carbon content of low-carbon series steel such as SPHC and the like are greatly different, molten steel is seriously oxidized when the converter discharges steel, the oxidability of ladle top slag is high, and the alkalinity is low, so that the modification treatment of the ladle top slag is needed in the LF refining stage, a large amount of aluminum particles and calcium carbide are needed to be added for manufacturing white slag to form reducing slag and improve the desulfurization capability, but the proportion and the adding amount of the aluminum particles and the calcium carbide are not easy to control, the slag regulation of the molten steel after entering the LF refining stage is often difficult, the slag regulation by heating the molten slag is needed, the conditions of long electrifying time, slow production rhythm and the like are caused, in addition, the cost of the aluminum particles is high.
Wherein, the molten steel peroxidation at the blowing end point of the converter is mainly shown in that the carbon content of the molten steel at the end point is less than or equal to 0.04 percent, the oxygen content is more than or equal to 800ppm, and the ferric oxide content in the slag is more than or equal to 13 percent; the molten steel is over-oxidized, which causes the addition amount of the deoxidizer to be increased, and leads to the rise of smelting cost.
Disclosure of Invention
The invention aims to solve the problems of difficult white slag adjustment, long electrifying time and slow production rhythm in the molten steel peroxidation and LF refining stages of converter tapping, and the content of acid-soluble aluminum is controlled by controlling the components and temperature at the end point of the converter and in the deoxidation alloying stage of the converter tapping, so that the molten steel peroxidation in the converter steelmaking is reduced or avoided; and the synthetic slag is added in the tapping process, and the deoxidation accelerant is added at the same time, so that the slag sample components and the proportion are effectively blended, the converter final slag directly forms yellow white slag, the slag melting and slagging are not needed in the LF refining stage, the LF refining step is simplified, the LF refining time is shortened, the productivity of the LF refining furnace is released, in addition, the power consumption and the addition amount of the deoxidizer in the LF refining stage are reduced, and the cost and the energy consumption are reduced.
In order to achieve the purpose, the invention adopts the following technical scheme:
a shallow treatment process suitable for SPHC low-carbon series steel grades comprises the following steps:
s1, molten iron pretreatment: the molten iron is subjected to desulfurization and slagging-off treatment through a KR desulfurization station, so that the sulfur content of the molten iron is less than or equal to 0.015 percent;
s2, smelting in a converter: charging the molten iron treated in the step S1 into a converter for smelting;
s3, converter end point control: the end point control temperature of the converter is 1640-1660 ℃, the sublance fixed carbon is more than or equal to 0.04 percent, the free oxygen of the molten steel is less than or equal to 800ppm, and the oxygen and the carbon are measured by a sublance probe;
s4, molten steel pretreatment in the converter tapping process:
in the tapping process, 3.3-3.5 kg/ton steel of aluminum-manganese-iron is added for deoxidation alloying, so that the acid-soluble aluminum in the molten steel entering the LF refining furnace is more than or equal to 0.010 percent, the acid-soluble aluminum content is measured by a low-oxygen probe, the oxygen in the steel is reduced along with the increase of the acid-soluble aluminum content, and the deoxidation effect is ensured by controlling the acid-soluble aluminum content;
after the deoxidation alloying is finished, adding a deoxidation accelerant and synthetic slag along the steel flow, and pretreating the molten steel to obtain yellow and white slag, wherein the total iron content in the slag is less than or equal to 1.5%; the addition amount of the deoxidation accelerant in each furnace is 0.8-1.2 kg/ton of steel, and the addition amount of the synthetic slag is 6-8 kg/ton of steel;
s5, LF refining furnace shallow treatment: transferring the molten steel tapped from the transfer furnace in the step S4 into an LF refining furnace for shallow treatment;
s6, pouring molten steel: and directly transferring the molten steel subjected to the shallow treatment in the step S5 to a continuous casting machine for casting.
On the basis of the original smelting process, the content of acid-soluble aluminum in molten steel is effectively controlled through deoxidation alloying so as to ensure the action effect of a deoxidation accelerant, the deoxidation accelerant is added along the steel flow in the converter tapping process to be matched with synthetic slag so as to promote the converter tapping process to generate yellow and white slag, the link of slagging and slagging in the LF refining stage is omitted, the slag entering the station in the initial stage of LF refining is the reducing slag, the adaptive adjustment is carried out on the LF refining process, slagging and deslagging are not needed, the step of LF refining is simplified, the time of the LF refining stage is effectively shortened, and the productivity of an LF refining furnace is released.
The technical scheme of the invention is as follows: in the step S4, the deoxidation accelerant comprises the following components by mass: 15-20% of Al2O3：40-50％，SiO2≤10％，CaO：8-15％，MgO≤7％，H2O is less than or equal to 1.5 percent, and the balance is impurities; the particle size of the deoxidation accelerant is as follows: 30-50 mm.
CaO-Al in deoxidation accelerant2O3The MgO has slag conglomeration property and plays a role in purifying molten steel; al rich in activation treatment2O3And the metal aluminum reacts with oxygen in the steel to play a role in deoxidation, so that a stronger reducing atmosphere is formed in the molten steel, and peroxidation is avoided; can promote sulfur in steel to be in CaOSiO2Medium polymerization, promoting molten steel desulfurization and yellow-white slag formation, and CaO and SiO2The alkalinity of the steel slag is improved; al (Al)2O3Has good foaming performance and can rapidly produce white slag (generation of a large amount of aluminate).
The technical scheme of the invention is as follows: the LF refining furnace shallow treatment in the step S5 comprises the following steps:
a1, after molten steel enters an LF refining furnace, stirring for 3 minutes by using argon gas at a station, wherein the stirring flow of the argon gas is 800 NL/min;
a2, after stirring of the argon gas, adjusting the flow of argon blowing at the bottom of the steel ladle to 150NL/min, and performing temperature and oxygen measurement on the molten steel by using a low-oxygen probe;
a3, after oxygen determination is finished, taking a molten steel sample for inspection, adjusting the flow of argon blowing at the bottom of the steel ladle to 800NL/min, and performing aluminum wire feeding and aluminum matching operation according to the determined oxygen content to control the aluminum content to be 0.050% -0.060%;
a4, after the aluminum preparation operation is finished, adjusting the flow rate of argon blowing at the bottom of the ladle to 150NL/min, adding 0.15-0.30 kg/ton of calcium carbide into molten steel, and starting to electrify and heat the molten steel;
a5, finely adjusting the components of the molten steel according to the components of the molten steel sample;
a6, feeding calcium-aluminum wires into the molten steel after LF refining treatment;
a7, after the calcium-aluminum wire feeding is finished, adjusting the argon flow rate of the ladle bottom blowing to 100NL/min, and starting soft blowing.
When molten steel is refined, yellow and white slag (reducing slag) is formed, and slag mixing is not needed, so that the production efficiency is improved; the LF refining furnace only needs to adjust the temperature and the components of the molten steel in the shallow treatment, and the refining and soft blowing time is obviously shortened, so that the power consumption is reduced, and the cost is saved.
The technical scheme of the invention is as follows: the argon stirring is that the pressure of the blown argon is 0.8-1.5 Mpa, so that the liquid level of the molten steel is slightly turned over, the shape of the exposed part of the molten steel is approximate to a circle, and the diameter of the circle is 100-250 mm.
The technical scheme of the invention is as follows: the fine adjustment of the components in the step A5 is carried out by means of manganese preparation or lime addition for desulfurization, so that the final sulfur content is less than or equal to 0.010 percent, and the Mn/S ratio is more than or equal to 15.
The technical scheme of the invention is as follows: the feeding amounts of the aluminum wire and the calcium-aluminum wire in the step A3 and the step A6 are both controlled at 100-150 m/furnace and the feeding speed of 2.0-2.5m/min, and the soft blowing time in the step A7 is not less than 8 min.
The technical scheme of the invention is as follows: the LF refining furnace shallow treatment process in the step S5 should be controlled at 20-25min, namely refining time, and soft blowing time is not included.
The technical scheme of the invention is as follows: in the step S6, the casting treatment process adopts a continuous casting machine to carry out full-protection casting, so that secondary oxidation of molten steel is avoided.
The invention has the beneficial effects that: (1) the carbon content and the oxygen content of the molten steel are controlled at the end point of the converter, so that the molten steel peroxidation is reduced or avoided; (2) the invention provides a shallow treatment process applied to SPHC low-carbon series steel grade, a deoxidation accelerant is used to be matched with synthetic slag in the tapping process, and the molten steel is pretreated at the same time, so that yellow and white slag is generated in the tapping process of a converter, the link of slagging in the LF refining stage is omitted, and the productivity of an LF refining furnace is released; (3) the deoxidation accelerant enables the molten steel deoxidation effect to be better in the converter tapping stage, enables the steel slag entering the refining stage to be in a reduction state, greatly prolongs the floating time of inclusions in the molten steel, enhances the molten steel purification effect and improves the molten steel quality; (4) the slag adjustment in the external refining is advanced to the tapping stage of the converter, and only the temperature and the components of the molten steel need to be adjusted, so that the adding amount of aluminum wires and calcium carbide is obviously reduced, and the refining and soft blowing time is obviously shortened, thereby reducing the power consumption and saving the cost.
Detailed Description
The present invention will be further described with reference to the following embodiments.
6 furnaces of SPHC-1 steel grades are continuously produced in 120t top-bottom combined blown furnaces of a certain steel mill in China, wherein examples 1-4 adopt the process control method disclosed by the invention, and the control process of comparative examples 1-2 adopts a normal process, so that the implementation effect of the invention is verified by comparison. The process control parameters and results are shown in tables 1-3.
Lime components and properties in examples 1-4 and comparative examples 1-2: CaO: 89.35% of SiO2: 0.91%, S: 0.008%, P: 0.006 percent, the balance of impurities, the activity 345 percent and the raw and over-burnt rate 10.1 percent.
The compositions and properties of the sintered ore in examples 1 to 4 and comparative examples 1 to 2 were as follows: TFe: 48.88%, FeO: 10.27%, CaO: 14.47% of SiO2: 6.25%, MgO: 2.81%, P: 1.23 percent, the balance of impurities and the granularity of 2-5 mm.
The additive in the smelting process can be purchased from the market or raw materials are purchased for corresponding proportioning, wherein the source and corresponding component information of the experimental additive are as follows:
the deoxidation accelerant is selected from a new refractory factory in the steel city area of Laiwu; the physical and chemical indexes of the deoxidation accelerant are as follows:
| item | Al％ | Al2O3％ | SiO2％ | CaO％ | MgO％ | H2O％ | Particle size, mm |
| Index (I) | 15-20 | 40-45 | ≤10 | 8-15 | ≤7 | ≤1.5 | 30-50 |
The aluminum-manganese-iron component comprises the following components in percentage by mass:
| item | C％ | Si％ | Mn％ | P％ | S％ | Al％ | Fe％ |
| Content (wt.) | 0.06 | 0.28 | 5.52 | 0.004 | 0.006 | 55.16 | 38.97 |
Synthetic slag: the lime and the fluorite are mixed according to the mass fraction of 9: 1;
aluminum wire: the mass fraction of Al is 99.77 percent, and the balance is impurities;
the calcium carbide is the existing product, purchased from the market, and only the powder is sampled and inspected without testing components when entering the factory;
the calcium-aluminum wire comprises the following components in percentage by mass: the content of Ca is 97.81 percent, the balance is Al, the mass of aluminum is 20.55 g/m, and the mass of calcium core is 50.76 g/m.
Example 1
The shallow treatment process suitable for the SPHC low-carbon series steel grade mainly aims at optimizing the pretreatment of molten steel in the steel discharging process to form yellow and white slag, and performing shallow treatment on the pretreated molten steel in an LF refining furnace to achieve the purpose of shortening the LF refining time. The method comprises the following steps:
s1, molten iron pretreatment: and the molten iron is subjected to desulfurization and slagging-off treatment through a KR desulfurization station, so that the sulfur content of the molten iron is less than or equal to 0.015 percent.
S2, smelting in a converter: and charging the molten iron treated in the step S1 into a converter for smelting.
S3, converter end point control: the end point control temperature of the converter is 1643 ℃, the sublance fixed carbon is 0.045%, the free oxygen of the molten steel is 687ppm, and the oxygen and the carbon are measured by a sublance probe.
S4, molten steel pretreatment in the converter tapping process:
in the tapping process, 409kg of aluminum-manganese-iron is added for deoxidation alloying, and the acid-soluble aluminum content in the molten steel entering the LF refining furnace is measured to be 0.022% by a low-oxygen probe;
after the deoxidation alloying is finished, adding a deoxidation accelerant and synthetic slag along the steel flow, pretreating the molten steel to obtain yellow and white slag, and measuring the total iron content in the slag to be 1.18%; the addition amount of the deoxidation accelerant in each furnace is 140kg, and the addition amount of the synthetic slag is 1000 kg.
S5, LF refining furnace shallow treatment: and transferring the molten steel tapped from the transfer furnace in the step S4 to an LF refining furnace for shallow treatment.
The shallow treatment of the LF refining furnace comprises the following steps:
a1, after molten steel enters an LF refining furnace, stirring for 3.5 minutes by entering station argon gas, wherein the argon gas is blown into the refining furnace under the condition that the pressure is 1.15Mpa and the stirring flow is 800 NL/min.
A2, after the stirring of the argon gas is finished, adjusting the flow of the argon blown from the bottom of the ladle to 150NL/min, and performing temperature measurement and oxygen determination on the molten steel by using a low-oxygen probe to finally measure the arrival oxygen determination of the LF refining furnace to be 5 ppm.
A3, after the oxygen determination is finished, taking a molten steel sample for inspection, adjusting the flow of argon blowing at the bottom of the steel ladle to 800NL/min, and carrying out aluminum wire feeding and aluminum distribution operation according to the determined oxygen content to control the aluminum content to be 0.050% -0.060%. The feeding amount of the aluminum wire is 230m, and the feeding speed is 2.25 m/min.
A4, after the aluminum preparation operation is finished, the flow rate of argon blowing at the bottom of the ladle is adjusted to 150NL/min, 10kg of calcium carbide is added into the molten steel, and the operation of electrifying and heating the molten steel is started.
A5, fine adjustment of the composition of molten steel is performed according to the composition of the molten steel sample. The fine adjustment of the components is carried out by a mode of manganese preparation or lime addition for desulfurization, so that the final sulfur content is less than or equal to 0.010 percent, and the Mn/S is more than or equal to 15 percent.
A6, feeding calcium-aluminum wires into the molten steel after LF refining treatment. The feeding amount of the calcium-aluminum wire is 130m, and the feeding speed is 2.25 m/min.
A7, after the calcium-aluminum wire feeding is finished, adjusting the argon flow rate of the ladle bottom blowing to 100NL/min, and starting soft blowing. The soft blowing time is 8min, the refining time of the LF refining furnace in the shallow treatment process is 22min, and the soft blowing time is not included.
S6, pouring molten steel: and directly transferring the molten steel subjected to the shallow treatment in the step S5 to a continuous casting machine for casting. The casting treatment process adopts a continuous casting machine to carry out full-protection casting, and avoids secondary oxidation of molten steel.
The casting speed of the continuous casting machine is normally controlled in the molten steel casting process, and no trepanning sign appears. And after the continuous casting machine finishes pouring, the casting blank is subjected to online inspection, the quality is normal, and the subsequent rolling quality is normal.
Examples 2 to 4
The process steps are the same as example 1, wherein the end point control of the converter and the process parameters of the LF refining furnace are finely adjusted, and the specific parameters are detailed in tables 1 and 3.
Examples 1-4 after treatment in the converter, the slag sample of the LF refining furnace has been formed into basic slag, i.e. reducing slag, SiO2The content is obviously reduced, the total iron content in the slag is less than 1.5 percent, yellow and white slag is formed, and the specific slag sample components are shown in table 2.
Comparative examples 1 and 2
Comparative example 1 and comparative example 2 are conventional smelting processes, and the process steps are different from those of examples 1 to 4 in that only synthetic slag is added in the molten steel pretreatment stage in the converter tapping process, specific parameters are shown in table 1, so that the slag sample of the LF refining furnace at the station is acid slag, yellow white slag is not formed, slag melting and slagging treatment are required in the refining stage of the LF refining furnace, the specific components of the slag sample of the LF refining furnace at the station are shown in table 2, and SiO is shown2The content is high, the slag sample is acidic, and the total iron content in the slag is more than 1.5 percent.
Meanwhile, compared with the embodiments 1 to 4, in the refining stage of the LF refining furnace, the station entering fixed oxygen amount is higher, the station entering fixed aluminum amount is lower, so that a large amount of aluminum wires and calcium carbide are required to be added for deoxidation and slag adjustment, and because the slag is required to be melted and adjusted by heating, the refining time and the power consumption are obviously increased compared with the embodiments 1 to 4, and specific parameters are detailed in a table 3.
TABLE 1 statistical tables for converter endpoint control in examples 1-4 and comparative examples 1-2
TABLE 2 comparison of slag sample compositions of examples 1-4 with comparative examples 1-2LF refining furnace
TABLE 3 statistical tables for controlling process parameters of examples 1-4 and comparative examples 1-2LF refining furnaces
And (3) comprehensive analysis:
as shown in Table 2, from the compositions of the in-station slag samples, the total iron content of the in-station slag of the furnaces of examples 1 to 4 is reduced by 29 percent compared with the furnaces of comparative example 1 and 2, and the total iron content of the in-station slag of the furnaces of examples 1 to 4 is lower than 1.5 percent, which indicates that the deoxidation effect of examples 1 to 4 is better than that of comparative example 1 and 2, and SiO is added to the in-station slag of the furnaces of examples 1 to 42The content is reduced by 59 percent on average compared with the furnace times of the comparative example 1 and the comparative example 2, and the alkalinity of the slag is mainly determined by CaO/SiO2The larger the ratio, the larger the basicity, and it can be seen from Table 2 that the heats of examples 1 to 4 are compared with the comparative example1 and a comparative example 2, the CaO content in the slag entering the station is increased by 8.8 percent on average; therefore, the alkalinity of the examples 1 to 4 is higher than that of the comparative example 1 and the normal heat of the comparative example 2, which shows that after the refining slagging process is moved to the converter tapping process, yellow and white slag (reducing slag) is formed in the slag when molten steel enters into LF refining, slagging is not needed in the LF refining stage, and the temperature and the components of the molten steel are only needed to be adjusted, so that the average time of refining and soft blowing is respectively reduced by 27 percent and 36 percent, the power consumption of LF refining is effectively reduced, and the average power consumption is reduced by 44.5 percent.
As shown in tables 1 and 3, in the examples 1 to 4, the content of acid-soluble aluminum is controlled by deoxidation alloying in the tapping stage of the converter, and a deoxidation accelerant is added along the steel flow and the content of the synthetic slag is adjusted, compared with the comparative examples 1 to 2, the average oxygen content of the molten steel entering the LF refining furnace for refining is reduced by 84%, the peroxidation of the molten steel is reduced or avoided, the average addition amounts of an aluminum wire and a carbon-calcium-aluminum wire in the refining stage of the LF refining furnace are respectively reduced by 42% and 87%, the raw material cost is saved, the heating time for temperature rise is shortened, the power consumption is reduced, and the cost investment is controlled.
According to the invention, the refining part slagging part is moved forward to the converter tapping process, the deoxidation accelerant is matched with the synthetic slag to pretreat the molten steel in the tapping process, the deoxidation and desulfurization effects are improved, so that the final slag of the converter meets the reducing slag required by the LF refining furnace, slag regulation is not required in the refining stage of the LF refining furnace, only the temperature and the components of the molten steel are required to be regulated, the refining time of the LF refining furnace is effectively shortened, the production capacity of the LF refining furnace is released, the power consumption is saved, and the Al slag entering the station in the initial refining stage of the LF refining furnace is improved2O3The content of the impurity in the molten steel greatly prolongs the floating time of the impurity in the molten steel, and improves the quality of the molten steel.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications made by the equivalent structures or equivalent processes in the present specification, or directly or indirectly applied to other related technical fields are included in the scope of the present invention.
Claims (8)
1. A shallow treatment process suitable for SPHC low-carbon series steel grades is characterized in that: the method comprises the following steps:
s1, molten iron pretreatment: the molten iron is subjected to desulfurization and slagging-off treatment through a KR desulfurization station, so that the sulfur content of the molten iron is less than or equal to 0.015 percent;
s2, smelting in a converter: charging the molten iron treated in the step S1 into a converter for smelting;
s3, converter end point control: the end point control temperature of the converter is 1640-1660 ℃, the sublance fixed carbon is more than or equal to 0.04 percent, the free oxygen of the molten steel is less than or equal to 800ppm, and the oxygen and the carbon are measured by a sublance probe;
s4, molten steel pretreatment in the converter tapping process:
adding 3.3-3.5 kg/ton steel of aluminum-manganese-iron in the tapping process, carrying out deoxidation alloying, ensuring that the acid-soluble aluminum in the molten steel entering the LF refining furnace is more than or equal to 0.010 percent, and measuring the content of the acid-soluble aluminum by using a low-oxygen probe;
after the deoxidation alloying is finished, adding a deoxidation accelerant and synthetic slag along the steel flow, and pretreating the molten steel to obtain yellow and white slag, wherein the total iron content in the slag is less than or equal to 1.5%; the addition amount of the deoxidation accelerant in each furnace is 0.8-1.2 kg/ton of steel, and the addition amount of the synthetic slag is 6-8 kg/ton of steel;
s5, LF refining furnace shallow treatment: transferring the molten steel tapped from the transfer furnace in the step S4 into an LF refining furnace for shallow treatment;
s6, pouring molten steel: and directly transferring the molten steel subjected to the shallow treatment in the step S5 to a continuous casting machine for casting.
2. A superficial treatment process applicable to SPHC low carbon series steel grades, according to claim 1, characterized in that: in the step S4, the deoxidation accelerant comprises the following components in percentage by mass: 15-20% of Al2O 3：40-50％，SiO 2≤10％，CaO：8-15％，MgO≤7％，H2O is less than or equal to 1.5 percent, and the balance is impurities; the particle size of the deoxidation accelerant is as follows: 30-50 mm.
3. A superficial treatment process applicable to SPHC low carbon series steel grades, according to claim 1, characterized in that: the LF refining furnace shallow treatment in the step S5 comprises the following steps:
a1, after molten steel enters an LF refining furnace, stirring for 3 minutes by using large argon, wherein the stirring flow of the large argon is 800 NL/min;
a2, after stirring of the argon gas, adjusting the flow of argon blowing at the bottom of the steel ladle to 150NL/min, and performing temperature and oxygen measurement on the molten steel by using a low-oxygen probe;
a3, after oxygen determination is finished, taking a molten steel sample for inspection, adjusting the flow of argon blowing at the bottom of the steel ladle to 800NL/min, and performing aluminum wire feeding and aluminum distribution operation according to the determined oxygen content to control the aluminum content to be 0.050-0.060%;
a4, after the aluminum preparation operation is finished, adjusting the flow rate of argon blowing at the bottom of the ladle to 150NL/min, adding 0.15-0.30 kg/ton of calcium carbide into molten steel, and starting to electrify and heat the molten steel;
a5, finely adjusting the components of the molten steel according to the components of the molten steel sample;
a6, feeding calcium-aluminum wires into the molten steel after LF refining treatment;
a7, after the calcium-aluminum wire feeding is finished, adjusting the argon flow rate of the ladle bottom blowing to 100NL/min, and starting soft blowing.
4. A superficial treatment process applicable to SPHC low carbon series steel grades, according to claim 3, characterized in that: the argon stirring is that the pressure of the blown argon is 0.8-1.5 Mpa, so that the liquid level of the molten steel is slightly turned over, the shape of the exposed part of the molten steel is approximate to a circle, and the diameter of the circle is 100-250 mm.
5. A superficial treatment process applicable to SPHC low carbon series steel grades, according to claim 3, characterized in that: the fine adjustment of the components in the step A5 is carried out by means of manganese preparation or lime addition for desulfurization, so that the final sulfur content is less than or equal to 0.010 percent, and the Mn/S ratio is more than or equal to 15.
6. A superficial treatment process applicable to SPHC low carbon series steel grades, according to claim 3, characterized in that: the feeding amounts of the aluminum wire and the calcium-aluminum wire in the step A3 and the step A6 are both controlled at 100-150 m/furnace and the feeding speed of 2.0-2.5m/min, and the soft blowing time in the step A7 is not less than 8 min.
7. A superficial treatment process applicable to SPHC low carbon series steel grades, according to claim 1, characterized in that: in the step S5, the shallow treatment process of the LF refining furnace should be controlled within 20-25min, and soft blowing time is not included.
8. A superficial treatment process applicable to SPHC low carbon series steel grades according to any one of claims 1 to 7, characterized in that: in the step S6, the casting treatment process adopts a continuous casting machine to carry out full-protection casting, so that secondary oxidation of molten steel is avoided.
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| CN115747614A (en) * | 2022-11-17 | 2023-03-07 | 唐山瑞丰钢铁（集团）有限公司 | Production method of steel for tinned substrate |
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