Low-cost low-temperature-resistant hot-rolled h-shaped steel and smelting method thereof

Abstract

The application discloses a low-cost low-temperature-resistant hot-rolled H-shaped steel, characterized in that the mass percentage of the chemical components comprises the following: C 0.08%-0.15%, Si 0.20%-0.40%, Mn 1.30%-1.40%, P≤0.025%, S≤0.015%, V 0.05%-0.06%, Cr≤0.01%, Ni≤0.01%, Cu≤0.01%, N 0.006%-0.010%, and the rest is Fe and impurities, and the total mass percentage is 100%. The application also discloses a smelting method thereof. The application aims to provide a low-cost low-temperature-resistant hot-rolled H-shaped steel and a smelting method thereof, and the performance of the H-shaped steel is excellent while the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smelting, in particular to a low-cost low-temperature-resistant hot-rolled H-shaped steel and a smelting method thereof. BACKGROUND

[0002] With the rapid development of the domestic steel structure industry, the demand for hot-rolled H-shaped steel products gradually develops towards high-end and differentiation, and the demand for low-temperature-resistant hot-rolled H-shaped steel is steadily increasing. On the premise of meeting the standard and user's use demand, the manufacturing cost is reduced and the enterprise profit growth point is increased through process and technical optimization. Reducing product cost can also reduce energy consumption, reduce carbon emissions in the production process, improve production efficiency, and realize green and low-carbon production. SUMMARY

[0003] The purpose of the present application is to provide a low-cost low-temperature-resistant hot-rolled H-shaped steel and a smelting method thereof, which can reduce the cost while having excellent performance.

[0004] To solve the above technical problems, the present application adopts the following technical scheme:

[0005] The low-cost low-temperature-resistant hot-rolled H-shaped steel according to the present application has a chemical composition with a mass percentage of: C 0.08%-0.15%, Si 0.20%-0.40%, Mn 1.30%-1.40%, P≤0.025%, S≤0.015%, V 0.05%-0.06%, Cr≤0.01%, Ni≤0.01%, Cu≤0.01%, N 0.006%-0.010%, and the rest is Fe and impurities, with a total mass percentage of 100%.

[0006] Further, the chemical composition has a mass percentage of: C 0.14%, Si 0.33%, Mn 1.32%, P 0.018%, S 0.007%, V 0.055%, Cr 0.007%, Ni 0.004%, Cu 0.009%, N 0.0063%, and the rest is Fe and impurities, with a total mass percentage of 100%.

[0007] Further, the chemical composition has a mass percentage of: C 0.11%, Si 0.24%, Mn 1.38%, P 0.012%, S 0.009%, V 0.051%, Cr 0.009%, Ni 0.006%, Cu 0.008%, N 0.0095%, and the rest is Fe and impurities, with a total mass percentage of 100%.

[0008] Further, the mass percentage of the chemical composition includes: C 0.09%, Si 0.20%, Mn 1.35%, P 0.023%, S 0.012%, V 0.059%, Cr 0.008%, Ni 0.003%, Cu 0.006%, N 0.0086%, and the rest is Fe and impurities, and the mass percentage of the total is 100%.

[0009] Further, the mass percentage of the chemical composition includes: C 0.10%, Si 0.38%, Mn 1.39%, P 0.020%, S 0.010%, V 0.053%, Cr 0.009%, Ni 0.007%, Cu 0.007%, N 0.0079%, and the rest is Fe and impurities, and the mass percentage of the total is 100%.

[0010] A smelting method of a low-cost low-temperature-resistant hot-rolled H-shaped steel, comprising:

[0011] The smelting process includes: hot metal pretreatment, converter smelting, LF refining, and shaped billet continuous casting.

[0012] The hot metal pretreatment adopts dry materials and no inclusions, and the scrap steel is 10-20 tons.

[0013] The hot metal tapping amount is controlled at 90±1 tons, and the charging S is less than or equal to 0.020%.

[0014] The combined blowing converter smelting controls the total charging amount at 105±2 tons, adopts low-high-low gun position control, the gun position is 1.1-1.5 m, the charging hot metal Si is less than or equal to 0.5%, single slag operation is adopted when Si is greater than 0.5%, the terminal basicity is controlled at 2.7-3.5, C is greater than or equal to 0.06%, T is greater than or equal to 1620℃, Al is used for final deoxidization, 300 kg of top slag lime is added during tapping, sliding plate slag stopping is adopted for tapping, and slagging is strictly prohibited;

[0015] The refining is heated for 8-10 minutes, according to the hot metal slag surface condition, 50-150 kg of bauxite, 30-80 kg of fluorite ball, 20-80 kg of aluminum iron, 10-30 kg of aluminum particles, and 400-600 kg of lime are added according to the tapping sulfur, when adding slag materials, the slag viscosity must be paid attention to, and the slag has good adsorption inclusion capacity; when the ladle weight is less than 120 tons, the deoxidization adopts silicon calcium barium deoxidization, silicon manganese is used to add Mn element, if the Si element is overloaded, manganese iron is used to add Mn element, V element is added by vanadium-nitrogen alloy at the end of refining, and 150 m of silicon calcium wire is fed, and the soft blowing time is greater than or equal to 15 minutes.

[0016] The long water gap of the large ladle adopts argon blowing protection pouring of asbestos bowl, uses a tundish covering agent to prevent the tundish molten steel liquid surface from being exposed, uses L7 protective slag supplied by Stoberg Company, the liquid slag layer is 8-12 mm; the crystallizer water pressure is greater than or equal to 0.8 Mpa; the secondary cooling adopts a middle cooling water table, and the immersion nozzle is inserted to a depth of 50-70 mm; and constant speed operation matching different profiled blank sections is adopted.

[0017] Further, the carbon equivalent CEV is less than or equal to 0.38%, and the welding crack sensitivity index Pcm is less than or equal to 0.23.

[0018] Further, the application is suitable for profiled blanks 350*290*100mm (BB1), 555*440*105mm (BB2), 730*370*90mm (BB3) and 1024*390*120mm (BB4).

[0019] Further, the finished H-shaped steel has the following performances: the lower yield strength ReL is greater than or equal to 400 MPa, the tensile strength Rm is greater than or equal to 520 MPa, the yield strength ratio is less than or equal to 0.83, the impact toughness at-20 DEG C is greater than or equal to 100 J, and the elongation after fracture is greater than or equal to 30%.

[0020] Compared with the prior art, the application has the following beneficial technical effects:

[0021] The crack rate of the finished H-shaped steel is stably controlled to be less than or equal to 0.5%.

[0022] The finished H-shaped steel has the following performances: the lower yield strength ReL is greater than or equal to 400 MPa, the tensile strength Rm is greater than or equal to 520 MPa, the yield strength ratio is less than or equal to 0.83, the impact toughness at-20 DEG C is greater than or equal to 100 J, and the elongation after fracture is greater than or equal to 30%. DETAILED DESCRIPTION

[0023] The application will be further described below

[0024] A low-cost low-temperature-resistant hot-rolled H-shaped steel and a smelting method thereof, the mass percentage of the chemical components of the H-shaped steel comprises: C 0.08%-0.15%, Si 0.20%-0.40%, Mn 1.30%-1.40%, P≤0.025%, S≤0.015%, V 0.05%-0.06%, Cr≤0.01%, Ni≤0.01%, Cu≤0.01%, N 0.006%-0.010%, the rest is Fe and impurities, the total mass percentage is 100%, the carbon equivalent CEV is less than or equal to 0.38%, and the welding crack sensitivity index Pcm is less than or equal to 0.23. The final H-shaped steel has the following performances: the lower yield strength ReL is greater than or equal to 400 MPa, the tensile strength Rm is greater than or equal to 520 MPa, the yield strength ratio is less than or equal to 0.83, the impact toughness at-20 DEG C is greater than or equal to 100 J, and the elongation after fracture is greater than or equal to 30%.

[0025] A low-cost low-temperature hot-rolled H-shaped steel smelting process is as follows: hot metal pretreatment converter smelting, LF refining, and shaped blank continuous casting.

[0026] The hot metal pretreatment adopts dry materials and no inclusions, and the scrap steel is 10-20 tons.

[0027] The hot metal tapping amount is controlled at 90±1 tons, and the tapping Si is ≤0.020%.

[0028] The combined blown converter smelting adopts low-high-low lance position control, the lance position is 1.1-1.5 m, the tapping Si is ≤0.5% for single slag operation, the tapping Si is >0.5% for double slag operation, the terminal point basicity is controlled at 2.7-3.5, C≥0.06%, T≥1620℃, the terminal deoxidization adopts Al deoxidization, 300 kg of top slag lime is added during tapping, the tapping adopts slide plate slag blocking, and slagging is strictly prohibited.

[0029] The refining in-position heating is 8-10 min, according to the hot metal in-position slag surface condition, 50-150 kg of bauxite, 30-80 kg of fluorite ball, 20-80 kg of aluminum iron added with sulfur, 10-30 kg of aluminum particles, and 400-600 kg of lime are added, when adding the slag material, the slag viscosity must be paid attention to, and the slag must have good adsorption inclusion capacity. When the ladle weight is less than 120 tons, the deoxidization adopts silicon calcium barium deoxidization, silicon manganese is used to add Mn element, if the Si element is overloaded, manganese iron is used to add Mn element, V element is added by vanadium nitrogen alloy at the end of refining, and 150 m of silicon calcium wire is fed, and the soft blowing time is greater than or equal to 15 min.

[0030] The continuous casting hot metal composition is C 0.08%-0.15%, Si 0.20%-0.40%, Mn 1.30%-1.40%, P≤0.025%, S≤0.015%, V 0.05%-0.06%, Cr≤0.01%, Ni≤0.01%, Cu≤0.01%, N 0.006%-0.010%, the rest is Fe and impurities, the mass fraction is 100%, the carbon equivalent CEV is ≤0.38%, and the welding crack sensitivity index Pcm is ≤0.23.

[0031] The carbon equivalent calculation formula is

[0032] CEV(%)=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15

[0033] The welding crack sensitivity index calculation formula is

[0034] Pcm(%)=C+Si / 30+Mn / 20+Cu / 20+Ni / 60+Cr / 20+Mo / 15+V / 10+5B

[0035] The long nozzle of the large ladle is used for argon blowing protection pouring with asbestos bowl, and a tundish covering agent is used to prevent the tundish liquid surface from being exposed. The L7 protective slag supplied by Stoberg Company is used, and the liquid slag layer is 8-12 mm. The crystallizer water pressure is greater than or equal to 0.8 Mpa; the secondary cooling adopts a middle cooling water table, and the immersion nozzle is inserted to a depth of 50-70 mm. According to different cross-sections of the shaped blank, constant speed operation matching the cross-sections is adopted.

[0036] It is suitable for shaped blanks 350*290*100mm (BB1), 555*440*105mm (BB2), 730*370*90mm (BB3), and 1024*390*120mm (BB4).

[0037] The crack rate of the finished H-shaped steel is stably controlled below 0.5%.

[0038] The finished H-shaped steel meets the following requirements: lower yield strength ReL≥400 MPa, tensile strength Rm≥520 MPa, yield strength ratio ≤0.83, impact toughness at-20℃≥100 J, and elongation after fracture ≥30%.

[0039] Table 1: Chemical composition of each example

[0040]

[0041] Table 2: Carbon equivalent of each example

[0042] Example Carbon equivalent CEV / % Welding crack sensitivity index Pcm Example 1 0.373 0.223 Example 2 0.353 0.193 Example 3 0.329 0.171 Example 4 0.345 0.188

[0043] Table 3: Crack rate of finished product of each example

[0044] Example Finished product crack rate / % Example 1 0.03 Example 2 0.04 Example 3 0.03 Example 4 0.04

[0045] Table 4: Mechanical properties of each example

[0046]

[0047] It can be seen that the embodiments of the present application reduce the cost by reasonably adjusting the components, and at the same time, the excellent mechanical properties are obtained by optimizing the process.

[0048] The above-described embodiments are only used to describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope of the present application defined by the claims.

Claims

1. A low-cost, low-temperature resistant hot-rolled H-beam, characterized in that: Its chemical composition by mass percentage includes: C 0.08%-0.15%, Si 0.20%-0.40%, Mn 1.30%-1.40%, P ≤0.025%, S≤0.015%, V 0.05%-0.06%, Cr ≤0.01%, Ni ≤0.01%, Cu ≤0.01%, N 0.006%-0.010%, with the remainder being Fe and impurities, totaling 100% by mass. Its smelting methods include: Smelting process: hot metal pretreatment, converter smelting, LF refining, and continuous casting of special-shaped billets; Iron pretreatment uses dry materials, free of impurities, and 10-20 tons of scrap steel; The amount of molten iron tapped is controlled at 90±1 tons, and the sulfur content (S) entering the furnace is ≤0.020%. For the combined blowing converter smelting, the total charge is controlled at 105±2 tons, using a low-high-low lance position control, with the lance position at 1.1~1.5m. For molten iron with Si≤0.5%, single slag operation is used, and for Si>0.5%, double slag operation is used. The final basicity is controlled at 2.7-3.5, C≥0.06%, T≥1620℃, and final deoxidation is performed with Al. 300kg of top slag quicklime is added during tapping, and a sliding plate is used to block slag during tapping. Slag feeding is strictly prohibited. After refining and heating for 8-10 minutes, add 50-150 kg of bauxite and 30-80 kg of fluorite balls as slag-refining agent, depending on the slag surface condition of the molten steel. Add 20-80 kg of ferroalumina, 10-30 kg of aluminum granules, and 400-600 kg of quicklime as sulfur, depending on the tapping sulfur. When adding slag materials, pay attention to the slag viscosity to ensure that the slag has a good ability to adsorb inclusions. When the ladle weight is less than 120 tons, deoxidation is carried out using silicon-calcium-barium deoxidation, and silicon-manganese is used with added Mn. If the Si element is overloaded, manganese-iron is used with added Mn. V element is added using vanadium-nitrogen alloy at the end of refining, and 150 m of silicon-calcium wire is fed. The soft blowing time is greater than or equal to 15 minutes. The ladle uses an asbestos bowl and argon blowing protection for casting, and uses a tundish covering agent to prevent the molten steel surface from being exposed. L7 protective slag supplied by Stöberg is used, with a liquid slag layer of 8-12mm. The crystallizer water pressure is ≥0.8Mpa. The secondary cooling uses an intermediate cooling water gauge, and the immersion nozzle is inserted to a depth of 50-70mm. A constant casting speed is used to match the different irregular billet cross-sections.

2. The low-cost, low-temperature resistant hot-rolled H-beam according to claim 1, characterized in that: Its chemical composition by mass percentage includes: C 0.14%, Si 0.33%, Mn 1.32%, P 0.018%, S 0.007%, V 0.055%, Cr 0.007%, Ni 0.004%, Cu 0.009%, N 0.0063%, with the remainder being Fe and impurities, totaling 100% by mass.

3. The low-cost, low-temperature resistant hot-rolled H-beam according to claim 1, characterized in that: Its chemical composition by mass percentage includes: C 0.11%, Si 0.24%, Mn 1.38%, P 0.012%, S 0.009%, V 0.051%, Cr 0.009%, Ni 0.006%, Cu 0.008%, N 0.0095%, with the remainder being Fe and impurities, totaling 100% by mass.

4. The low-cost, low-temperature resistant hot-rolled H-beam according to claim 1, characterized in that: Its chemical composition by mass percentage includes: C 0.09%, Si 0.20%, Mn 1.35%, P 0.023%, S 0.012%, V 0.059%, Cr 0.008%, Ni 0.003%, Cu 0.006%, N 0.0086%, with the remainder being Fe and impurities, totaling 100% by mass.

5. The low-cost, low-temperature resistant hot-rolled H-beam according to claim 1, characterized in that: Its chemical composition by mass percentage includes: C 0.10%, Si 0.38%, Mn 1.39%, P 0.020%, S 0.010%, V 0.053%, Cr 0.009%, Ni 0.007%, Cu 0.007%, N 0.0079%, with the remainder being Fe and impurities, totaling 100% by mass.

6. The low-cost, low-temperature resistant hot-rolled H-beam according to claim 1, characterized in that: Carbon equivalent (CEV) ≤ 0.38%, weld crack sensitivity index (Pcm) ≤ 0.

23.

7. The low-cost, low-temperature resistant hot-rolled H-beam according to claim 1, characterized in that: The finished H-beams meet the following performance requirements: lower yield strength ReL≥400MPa, tensile strength Rm≥520MPa, yield-to-tensile ratio≤0.83, impact toughness at -20℃≥100J, and elongation after fracture≥30%.

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