CN-122013030-A - Continuous casting billet for acid-resistant pipeline steel and preparation method and application thereof

CN122013030ACN 122013030 ACN122013030 ACN 122013030ACN-122013030-A

Abstract

The invention relates to the technical field of steelmaking continuous casting, in particular to a continuous casting billet for acid-resistant pipeline steel, and a preparation method and application thereof. The preparation method of the continuous casting blank for the acid-resistant pipeline steel comprises the steps of molten iron pretreatment, converter smelting, LF refining, RH refining and continuous casting, chemical components of the continuous casting blank are controlled in sequence, the strength of argon blowing at the bottom of a steel ladle is controlled according to different operation stages in the process of converter smelting tapping and LF refining, crystallizer covering slag with specific alkalinity, melting point and viscosity is adopted in the continuous casting process, a secondary cooling zone is divided into 9 cooling zones, the water distribution of each zone is accurately controlled, and a light and heavy pressing process of a sector section is combined. After acid etching, the continuous casting billet prepared by the method has the advantages of center segregation not higher than C0.5 level, no center porosity or shrinkage cavity, no intermediate crack, good surface quality and inclusion not higher than 1 level.

Inventors

LI QIANG
MA JIANCHAO
ZHOU JIAN
JIN YUKAI
ZOU CHANGDONG

Assignees

江苏省沙钢钢铁研究院有限公司
江苏沙钢钢铁有限公司
江苏沙钢集团有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The preparation method of the continuous casting billet for the acid-resistant pipeline steel is characterized by comprising the procedures of molten iron pretreatment, converter smelting, LF refining, RH refining and continuous casting which are sequentially carried out, wherein the chemical components of the continuous casting billet are controlled to be ：C：0.03~0.07%、Si：0.10~0.30%、Mn：0.50~1.00%、Ni：0.2~0.4%、Nb：0.03~0.05%、V：0.05~0.07%、P≤0.010%、S≤0.0010%、Al：0.02~0.04%、Mo≤0.02%、Ti≤0.0020%、O≤0.0010%、N≤0.0030%、H≤0.00015%, in percentage by mass, and the balance of Fe and other unavoidable impurities; In the tapping process of converter smelting, when the tapping amount is 60t, controlling the strength of the argon bottom-blown gas of the ladle to be 5.0-6.0L/(min.t), and when the tapping amount is 120t, controlling the strength of the argon bottom-blown gas of the ladle to be 4.1-4.9L/(min.t); In the LF refining process, controlling the strength of bottom-blown argon of a ladle according to an operation type, wherein the strength of the bottom-blown argon is controlled to be 3.1-3.9L/(min & t) when an alloy fine tuning component is added, the strength of the bottom-blown argon is controlled to be 2.1-2.9L/(min & t) when lime and fluorite are added for slag formation, the strength of the bottom-blown argon is controlled to be 1.5-1.9L/(min & t) when calcium carbide is added for deoxidation, the strength of the bottom-blown argon is controlled to be 1.0-1.4L/(min & t) when power is applied and heating is carried out, and the strength of the bottom-blown argon is controlled to be 0.3-0.7L/(min & t) when no operation is carried out; In the continuous casting process, casting is carried out by adopting crystallizer casting powder, the binary alkalinity CaO/SiO 2 of the casting powder is 1.00-1.15, the melting point is 1030-1090 ℃, and the viscosity at 1300 ℃ is 0.12-0.22 Pa.s; In the continuous casting process, the secondary cooling zone is divided into 9 cooling zones, wherein a foot roller section corresponds to a1 zone, a zero section corresponds to 2-4 zones, a 1# to 2# fan section corresponds to a5 zone, a 3# to 4# fan section corresponds to a6 zone, a 5# to 7# fan section corresponds to a 7 zone, an 8# to 9# fan section corresponds to an 8 zone, and a 10# to 12# fan section corresponds to a 9 zone, and the water content of the 1-9 zones accounts for 13-16% of the total water content of the secondary cooling zone and is controlled to be respectively 13-16% of the 1 zone, 14-17% of the 2 zone, 15-18% of the 3 zone, 10-13% of the 4 zone, 7-10% of the 5 zone, 6-9% of the 7 zone, 5-7% of the 8 zone and 10-13% of the 9 zone; in the continuous casting process, the 9# to 11# fan-shaped sections are controlled to perform light rolling, the total rolling reduction of the light rolling reduction is 5 to 7mm, the 12# fan-shaped sections perform heavy rolling, and the rolling reduction of the heavy rolling reduction is 20 to 25mm.
2. The preparation method of the molten iron pretreatment according to claim 1, wherein in the step of molten iron pretreatment, desulfurization treatment is carried out by adopting a desulfurizing agent, wherein the mass ratio of CaO to CaF in the desulfurizing agent is (8-10) 1, the ton iron consumption of the desulfurizing agent is 5-7 kg, the mass ratio of the desulfurizing agent to 5mm is more than or equal to 95%, the mass ratio of particles smaller than 3mm is less than or equal to 3%, the mass ratio of particles larger than 5mm is less than or equal to 2%, the temperature of molten iron after desulfurization is more than or equal to 1300℃, S and less than or equal to 0.0010%, and the slag removal rate is more than or equal to 98%.
3. The preparation method of the steel ladle according to claim 1 or 2, wherein in the converter smelting process, clean scrap steel and desulfurized molten iron are added for smelting, the scrap steel ratio is controlled to be less than or equal to 23wt%, top-bottom combined blowing is adopted for decarburization and heating, top-blown oxygen flow is 3.8-4.0 ten thousand m 3 /h, oxygen supply time is 12-14 min, bottom-blown gas flow is 650-640 m 3 /h, bottom-blown carbon dioxide time is 30-32 min, the molten steel temperature is controlled to be more than or equal to 1630 ℃ during tapping, P is controlled to be less than or equal to 0.010%, S is controlled to be less than or equal to 0.0015%, C is controlled to 0.01% -0.03%, ladle bottom blowing is started during tapping, and aluminum blocks, ferrosilicon, manganese metal and nickel plates are added into the ladle for adjusting molten steel components when the tapping amount is 60 t.
4. The preparation method of the ladle furnace according to claim 1 or 2, wherein in the LF refining process, the ladle is opened for bottom blowing in the whole course after molten steel enters a station, the flow of bottom blowing argon is regulated according to the operation type, the flow is electrified and heated, alloy, lime and synthetic slag are added to regulate the molten steel components and slag formation, the total slag quantity of refining is 12-15 kg/t of steel, the slag components are ：CaO：53%~57%、Al 2 O 3 ：25%~28%、SiO 2 ：5%~7%、MgO：5%~8%、CaF 2 ：3%~6%、T.Fe+MnO≤1.0% in percentage by mass and other unavoidable impurity components, and the tapping temperature is controlled at 1615-1625 ℃ after the LF refining is finished; And/or performing calcium treatment after the LF refining is finished, wherein the content of calcium wire feeding quantity Q and molten steel Al meet the relation of Q=70+ (Al-0.02) multiplied by 5000, wherein Al is the mass percent of aluminum element in the molten steel, the unit of Q is m, the weight of pure calcium wire calcium core rice for calcium treatment is 60-70 g/m, the thickness of iron sheet is 2.3-2.7 mm, the wire feeding speed is 1.5-2.5 m/s, and the content of Ca in the molten steel after calcium treatment is 0.0013% -0.0018%.
5. The preparation method according to claim 1 or 2, wherein in the RH refining step, the vacuum chamber pressure is less than or equal to 1.5mbar, the molten steel circulation treatment time is more than or equal to 15min, the lifting gas flow rate is 150-200 m 3 /min, the Ca content of the molten steel after the air break is 0.0005-0.0008%, the H is less than or equal to 0.00018%, and the temperature is 1575-1585 ℃.
6. The preparation method of the continuous casting process according to claim 1 or 2, wherein in the continuous casting process, the standing time is more than or equal to 8 minutes after the steel ladle is lifted to a continuous casting platform, a high-alkalinity covering agent is adopted in a tundish, the consumption of the covering agent per ton of steel is 0.3-0.4 kg, the particle size is 2-4 mm and is more than or equal to 97%, the covering agent comprises SiO 2 ：10%~15%、CaO：45%~50%、MgO：10%~15%、Al 2 O 3 ：25%~35%、Fe 2 O 3 ：1%~3%; parts by mass percent of the whole-process argon blowing of the tundish, the argon blowing flow of a long nozzle is 150-250L/min, the argon blowing flow of a stopper rod and an immersed nozzle is 3-5L/min, the argon flow of a pouring area is 400-500L/min, and the argon flow of an impact area is 100-150L/min; And/or in the continuous casting process, controlling the superheat degree of the molten steel in the tundish to be 30-40 ℃, the pulling speed of a continuous casting machine to be 0.9-1.1 m/min, the specific water quantity of the secondary cooling zone to be 0.6-0.7L/kg, and the section size of the continuous casting billet to be 250mm× (2100-2700) mm.
7. The production method according to claim 1 or 2, wherein in the continuous casting process, chemical components of the mold flux are ：SiO 2 ：27%~29%、CaO：29%~31%、MgO：1.0%~3.0%、Fe 2 O 3 ：1%~3%、Al 2 O 3 ：5%~7%、Na 2 O：8%~10%、F：8%~10%、C：9%~11%, in mass percent and the balance is unavoidable impurities; And/or in the continuous casting process, the thickness of a casting powder slag layer in the crystallizer is 80-130 mm, the thickness of a liquid slag layer is 8-13 mm, and the insertion depth of a tundish submerged nozzle is 130-210 mm; And/or in the continuous casting process, the insertion depth of the immersed nozzle of the tundish is adjusted according to the broken surface width of the continuous casting machine, wherein the insertion depth is 150-170 mm when the section width is 2100-2300 mm, 170-190 mm when the section width is 2300-2500 mm, and 190-210 mm when the section width is 2500-2700 mm.
8. The preparation method according to claim 1 or 2, wherein in the continuous casting process, water in a region 1 is distributed into narrow sides and wide sides of the continuous casting billet, the water quantity of the narrow sides accounts for 50% -60% of the water quantity in the region 1, the water quantity of the wide sides accounts for 40% -50% of the water quantity in the region 1, water in regions 2,3 and 4 is distributed into the wide centers and wide sides of the continuous casting billet, the water quantity of the wide centers accounts for 30% -40% of the water quantity in regions 2,3 and 4, the water quantity of the wide sides accounts for 60% -70% of the water quantity in regions 2,3 and 4, the temperature of corners of the continuous casting billet before entering a 5# sector is more than or equal to 910 ℃, and the difference between the highest surface temperature and the lowest temperature is less than or equal to 18 ℃; And/or in the continuous casting process, the roll gap shrinkage of the foot roll section and the zero section is 0.05-0.10 mm, the roll gap shrinkage of the No. 1-No. 4 sector section is 0.10-0.15 mm, the roll gap shrinkage of the No. 5-No. 8 sector section is 0.15-0.20 mm, the rolling reduction of the No. 9 section accounts for 10% -15% of the total soft reduction, the rolling reduction of the No. 10 section accounts for 20% -25%, the rolling reduction of the No. 11 section accounts for 60% -70%, each roll rolling reduction of the No. 12 sector section is independently controlled, the maximum rolling reduction of a single roll is 6mm, the solidification end point of the wide surface center position of the continuous casting blank is positioned in the range of the No. 11 sector section, and the continuous casting blank is subjected to hot-charging hot-rolling or cold-stacking after flame cutting sizing.
9. The continuous casting slab for acid-resistant pipeline steel, which is characterized by being prepared by the preparation method of the continuous casting slab for acid-resistant pipeline steel according to any one of claims 1 to 8.
10. Use of the continuous casting slab for acid-fast pipeline steel according to claim 9 for producing acid-fast pipeline steel.

Description

Continuous casting billet for acid-resistant pipeline steel and preparation method and application thereof Technical Field The invention relates to the technical field of steelmaking continuous casting, in particular to a continuous casting billet for acid-resistant pipeline steel, and a preparation method and application thereof. Background The corrosive media such as H 2 S contained in acid oil and gas fields pose serious challenges for the safety and service life of conveying pipelines, and development of high-quality acid-resistant pipeline steel with good Hydrogen Induced Cracking (HIC) resistance is needed. The continuous casting process is a key link affecting the HIC resistance of the pipeline steel, and the inclusion type, the surface quality and the internal quality of the continuous casting blank directly determine the comprehensive performance of the final product. At present, the quality control of the continuous casting blank mainly works around the parameters of the roll gap precision of the sector section, the superheat degree of molten steel in the tundish, the drawing speed, the specific water quantity of the secondary cooling zone, the rolling interval, the rolling reduction and the like so as to improve the central quality of the continuous casting blank. However, most of the prior art focuses on single index control of center segregation or internal cracks, and cannot fully consider cooperative regulation and control of surface quality and inclusion types of continuous casting billets, so that the comprehensive quality requirements of acid-resistant pipeline steel on surface quality control, compact center and high cleanliness of the continuous casting billets are difficult to meet. Disclosure of Invention The invention provides a continuous casting billet for acid-resistant pipeline steel, and a preparation method and application thereof, and aims to solve the problem that the surface quality, center segregation and inclusions of the continuous casting billet of the acid-resistant pipeline steel are difficult to synchronously control in the prior art, so that the comprehensive quality of the continuous casting billet cannot meet the production requirement of high-grade acid-resistant pipeline steel. In a first aspect, the invention provides a method for preparing a continuous casting billet for acid-resistant pipeline steel, which comprises the steps of molten iron pretreatment, converter smelting, LF refining, RH refining and continuous casting which are sequentially carried out, wherein the chemical components of the continuous casting billet are controlled to be ：C：0.03~0.07%、Si：0.10~0.30%、Mn：0.50~1.00%、Ni：0.2~0.4%、Nb：0.03~0.05%、V：0.05~0.07%、P≤0.010%、S≤0.0010%、Al：0.02~0.04%、Mo≤0.02%、Ti≤0.0020%、O≤0.0010%、N≤0.0030%、H≤0.00015%, in percentage by mass, and the balance of Fe and other unavoidable impurities; In the tapping process of converter smelting, when the tapping amount is 60t, controlling the strength of the argon bottom-blown gas of the ladle to be 5.0-6.0L/(min.t), and when the tapping amount is 120t, controlling the strength of the argon bottom-blown gas of the ladle to be 4.1-4.9L/(min.t); In the LF refining process, controlling the strength of bottom-blown argon of a ladle according to an operation type, wherein the strength of the bottom-blown argon is controlled to be 3.1-3.9L/(min & t) when an alloy fine tuning component is added, the strength of the bottom-blown argon is controlled to be 2.1-2.9L/(min & t) when lime and fluorite are added for slag formation, the strength of the bottom-blown argon is controlled to be 1.5-1.9L/(min & t) when calcium carbide CaC 2 is added for deoxidation, the strength of the bottom-blown argon is controlled to be 1.0-1.4L/(min & t) when power is applied and heating is carried out, and the strength of the bottom-blown argon is controlled to be 0.3-0.7L/(min & t) when no operation is carried out; In the continuous casting process, casting is carried out by adopting crystallizer casting powder, the binary alkalinity CaO/SiO 2 of the casting powder is 1.00-1.15, the melting point is 1030-1090 ℃, and the viscosity at 1300 ℃ is 0.12-0.22 Pa.s; In the continuous casting process, the secondary cooling zone is divided into 9 cooling zones, wherein a foot roller section corresponds to a1 zone, a zero section corresponds to 2-4 zones, a 1# to 2# fan section corresponds to a5 zone, a 3# to 4# fan section corresponds to a6 zone, a 5# to 7# fan section corresponds to a 7 zone, an 8# to 9# fan section corresponds to an 8 zone, and a 10# to 12# fan section corresponds to a 9 zone, and the water content of the 1-9 zones accounts for 13-16% of the total water content of the secondary cooling zone and is controlled to be respectively 13-16% of the 1 zone, 14-17% of the 2 zone, 15-18% of the 3 zone, 10-13% of the 4 zone, 7-10% of the 5 zone, 6-9% of the 7 zone, 5-7% of the 8 zone and 10-13% of the 9 zone; in the continuous casting process, the 9# to 11# fan-sh