A rare earth low-alloy high-strength corrosion-resistant low-temperature low-yield ratio hot-rolled H-shaped steel for long-span steel structures and a manufacturing method thereof

Abstract

The application discloses a rare earth low-alloy high-strength corrosion-resistant low-temperature-resistant low-yield ratio hot-rolled H-shaped steel for large-span steel structures, which comprises the following components: C 0.09%-0.13%, Si 0.40%-0.50%, Mn 1.20%-1.30%, P 0.01%-0.03%, S≤0.010%, V 0.04%-0.05%, Cr 0.25%-0.30%, Ni 0.13%-0.15%, Cu 0.25%-0.30%, Ce 0.0010%-0.0030%, N 0.0050%-0.0070% and O≤0.0025%. A manufacturing method thereof is also disclosed. The H-shaped steel manufactured by the application satisfies the following conditions: lower yield strength ReL≥380MPa, tensile strength Rm≥520MPa, yield ratio≤0.75, impact toughness at-60 DEG C≥80J and elongation after fracture≥30%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smelting, and in particular to a rare earth low-alloy high-strength corrosion-resistant low-temperature-resistant low-yield ratio hot-rolled H-shaped steel for large-span steel structures and a manufacturing method thereof. BACKGROUND

[0002] In recent years, under the background of the country promoting high-quality development, the engineering construction industry is moving towards high-end, intelligent and green. In the engineering and construction steel, using high-performance steel products to replace low-performance grade steel products can effectively reduce the use of steel products and achieve carbon emission reduction. As an important basic material for the engineering construction industry, steel products are developing towards large specifications, high strength and high function.

[0003] With the increasingly novel and complex building shapes, large-span steel structures are increasingly frequently applied, becoming the main structure type used in stadiums, exhibition halls, airports, bridges and large underground buildings. Hot-rolled H-shaped steel is an important raw material for large-span steel structures, and it is urgent to develop hot-rolled H-shaped steel products with excellent comprehensive performance to meet the needs of long service life, high seismic resistance and lightweight use of large-span structures. SUMMARY

[0004] To solve the above technical problems, the purpose of the present application is to provide a rare earth low-alloy high-strength corrosion-resistant low-temperature-resistant low-yield ratio hot-rolled H-shaped steel for large-span steel structures and a manufacturing method thereof.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] The rare earth low-alloy high-strength corrosion-resistant low-temperature-resistant low-yield ratio hot-rolled H-shaped steel for large-span steel structures has a chemical composition with a mass percentage of: C 0.09%-0.13%, Si 0.40%-0.50%, Mn 1.20%-1.30%, P 0.01%-0.03%, S≤0.010%, V 0.04%-0.05%, Cr 0.25%-0.30%, Ni 0.13%-0.15%, Cu 0.25%-0.30%, Ce 0.0010%-0.0030%, N 0.0050%-0.0070%, O≤0.0025%, the rest being Fe and impurities, and the mass fraction of all components totaling 100%.

[0007] Further, the chemical composition has a mass percentage of: C 0.12%, Si 0.45%, Mn 1.23%, P 0.026%, S 0.007%, V 0.046%, Cr 0.27%, Ni 0.13%, Cu 0.28%, Ce 0.0018%, N 0.0065%, O 0.0023%, the rest being Fe and impurities, and the mass fraction of all components totaling 100%.

[0008] Further, the mass percentage of its chemical composition includes: C 0.10%, Si 0.48%, Mn 1.29%, P 0.023%, S 0.005%, V 0.042%, Cr 0.26%, Ni 0.15%, Cu 0.27%, Ce 0.0023%, N 0.0058%, O 0.0018%, and the rest is Fe and impurities, and the mass percentage of the total is 100%.

[0009] Further, the mass percentage of its chemical composition includes: C 0.09%, Si 0.43%, Mn 1.25%, P 0.015%, S 0.006%, V 0.048%, Cr 0.29%, Ni 0.14%, Cu 0.26%, Ce 0.0015%, N 0.0052%, O 0.0019%, and the rest is Fe and impurities, and the mass percentage of the total is 100%.

[0010] Further, the mass percentage of its chemical composition includes: C 0.13%, Si 0.41%, Mn 1.26%, P 0.028%, S 0.005%, V 0.043%, Cr 0.28%, Ni 0.14%, Cu 0.29%, Ce 0.0020%, N 0.0064%, O 0.0015%, and the rest is Fe and impurities, and the mass percentage of the total is 100%.

[0011] A manufacturing method of a rare earth low-alloy high-strength corrosion-resistant low-temperature-resistant low-yield ratio hot-rolled H-shaped steel for long-span steel structures, comprising:

[0012] The smelting process includes KR desulfurization, converter smelting, LF refining, VD vacuum degassing, and continuous casting of special-shaped billets, and slow cooling of the cast billets.

[0013] The materials are ensured to be dry and free of inclusions, and the amount of scrap steel used is 10-20 tons; the tapping amount of molten iron is controlled at 90±1 tons, and the S content entering the furnace is less than or equal to 0.020%;

[0014] The converter is smelted by complex blowing, the total charging amount is controlled at 105±2 tons, low-high-low gun position control is adopted, and the gun position is 1.1m-1.5m; single-slag operation is adopted when the Si content of the molten iron entering the furnace is less than or equal to 0.5, double-slag operation is adopted when the Si content is greater than 0.5, the terminal basicity is controlled at 2.7-3.5, C is greater than or equal to 0.06%, and T is greater than or equal to 1620℃; Al is used for deoxidation, and the amount of 80% aluminum-iron added is 50kg-100kg per furnace; lime is added to the top slag at 280-320kg when tapping, and a slide plate is used to block the slag at the terminal point;

[0015] Refining in place heating 8min-10min, according to the molten steel in place slag, adding slagging agent bauxite 50-150kg, fluorite ball 0-80kg, according to the sulfur plus aluminum iron 20-80kg, aluminum particles 10-30kg, lime 400-600kg; according to the color, viscosity of the slag, add aluminum particles, lime, until the yellow white slag after the temperature operation; molten steel temperature to 1635℃-1655℃, observe the slag, according to the viscosity of the slag, add slagging agent or lime, ensure the viscosity of the slag is appropriate; when the ladle weight is less than 120 tons, deoxidation using silicon calcium barium deoxidation; refining off-site temperature control ≥ L liquidus 1514℃+(105℃-140℃), using silicon manganese plus Mn element, if Si element overload using manganese iron plus Mn element, V element using vanadium nitrogen alloy plus, Ce using 30% cerium iron alloy plus;

[0016] VD vacuum degassing, vacuum degree ≤100Pa; deep vacuum treatment time ≥13min; after breaking the double line argon open, double line argon 200NL / min-400NL / min, after the slag surface boiling, feeding calcium line 150m-200m, feeding process adding 30% cerium iron alloy;

[0017] Ladle long nozzle using asbestos bowl and long nozzle argon protection pouring, using tundish covering agent, to prevent tundish molten steel liquid surface bare, using L7 protective slag supplied by Stoberg company, liquid slag layer 8mm-12mm, superheat control in 20-35℃, using automatic control of special shape billet single nozzle stopper for special shape billet BB2 section, drawing speed control in 0.7-0.8m / min, mold water pressure ≥0.8Mpa; submerged entry nozzle insertion depth 50-70mm, two cooling using middle cold water table; casting billet slow cooling time greater than 24h, under the cover;

[0018] Rolling process: step heating furnace, BD breakdown, CCS universal rolling, step cooling bed cooling; among them:

[0019] Preheating temperature ≤900℃, heating I temperature ≤1180℃, heating II temperature 1150℃-1330℃, soaking temperature 1200℃-1260℃, discharge temperature ≥1180℃, in the furnace time 120min-220min;

[0020] BD1 breakdown, rolling temperature 1170℃-1200℃, according to the final specification of the product to determine the rolling pass, total reduction ≥50%;

[0021] CCS universal rolling, the last pass temperature can be controlled in 940℃-980℃;

[0022] Cooling bed natural cooling, after the finished product temperature is lower than 100℃, straightening, sawing.

[0023] Further, the carbon equivalent CEV is less than or equal to 0.45%, the atmospheric corrosion resistance index I is greater than or equal to 6.0; the performance satisfies: the lower yield strength ReL is greater than or equal to 380 MPa, the tensile strength Rm is greater than or equal to 520 MPa, the yield ratio is less than or equal to 0.75, the impact toughness at-60 DEG C is greater than or equal to 80 J, and the elongation after fracture is greater than or equal to 30%.

[0024] Compared with the prior art, the present application has the beneficial technical effects:

[0025] The carbon equivalent CEV of the rare earth low-alloy high-strength corrosion-resistant low-temperature low-yield ratio hot-rolled H-shaped steel for long-span steel structure is less than or equal to 0.45%, the atmospheric corrosion resistance index I is greater than or equal to 6.0; the performance satisfies: the lower yield strength ReL is greater than or equal to 380 MPa, the tensile strength Rm is greater than or equal to 520 MPa, the yield ratio is less than or equal to 0.75, the impact toughness at-60 DEG C is greater than or equal to 80 J, and the elongation after fracture is greater than or equal to 30%. DETAILED DESCRIPTION

[0026] The present application will be further described below in combination with specific examples.

[0027] Table 1 Chemical composition of each example

[0028]

[0029] Table 2 Carbon equivalent of each example

[0030] Example Carbon equivalent CEV / % Atmospheric corrosion resistance index I Example 1 0.416 6.32 Example 2 0.403 6.27 Example 3 0.393 6.01 Example 4 0.433 6.22

[0031] Table 3 Rolling and finishing temperature of each example

[0032] Example Breakdown temperature (°C) Finishing temperature (°C) Example 1 1185 953 Example 2 1195 962 Example 3 1180 950 Example 4 1200 976

[0033] Table 4 Mechanical properties of each example

[0034]

[0035] Table 4 Atmospheric corrosion resistance of each example

[0036] Example Relative corrosion rate relative to Q235A Example 1 58％ Example 2 55％ Example 3 57％ Example 4 56％

[0037] The above-described examples are only used to describe the preferred modes of the present application, and do not limit the scope of the present application, and various modifications and improvements of the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application defined by the claims.

Claims

1. A rare earth low alloy high strength corrosion resistant low temperature resistant low yield ratio hot-rolled H-shaped steel for long-span steel structures, characterized in that: The mass percentage of the chemical composition includes: C 0.09%-0.13%, Si 0.40%-0.50%, Mn 1.20%-1.30%, P 0.01%-0.03%, S≤0.010%, V 0.04%-0.05%, Cr 0.25%-0.30%, Ni 0.13%-0.15%, Cu 0.25%-0.30%, Ce 0.0010%-0.0030%, N 0.0050%-0.0070%, O≤0.0025%, and the rest is Fe and impurities, with the total mass percentage being 100%; ​ The manufacturing method comprises: The smelting process is as follows: KR desulfurization, converter smelting, LF refining, VD vacuum degassing, beam blank continuous casting, and slow cooling of the casting blank; The material is ensured to be dry and free of inclusions, and the amount of scrap steel used is 10-20 tons; the tapping amount of molten iron is controlled at 90±1 tons, and the S content in the molten iron is less than or equal to 0.020% before being charged into the furnace; The total charging amount is controlled at 105±2 tons, and the gun position is controlled at low-high-low, with the gun position being 1.1m-1.5m; when the Si content in the molten iron is less than or equal to 0.5, single-slag operation is adopted, and when the Si content is greater than 0.5, double-slag operation is adopted; the terminal point basicity is controlled at 2.7-3.5, the C content is greater than or equal to 0.06%, and the T is greater than or equal to 1620℃; Al is used for final deoxidization, and the amount of 80% aluminum-iron added is 50kg-100kg per furnace; lime 280-320kg is added when tapping, and the terminal point is blocked by a slide plate; The refining in position is heated for 8min-10min, and according to the molten steel in position slag surface condition, bauxite 50-150kg, fluorite ball 0-80kg, according to tapping sulfur plus aluminum-iron 20-80kg, aluminum particles 10-30kg, lime 400-600kg are added; according to the color and viscosity of the slag, aluminum particles and lime are added until the slag is yellow-white, and then the temperature is raised; the molten steel is heated to 1635℃-1655℃, the slag condition is observed, and according to the viscosity of the slag, the slag agent or lime is added to ensure the appropriate viscosity of the slag; when the weight of the ladle is less than 120 tons, silicon-calcium-barium deoxidization is used; the refining off-site temperature is controlled at liquidus 1514℃+105℃ to 1514℃+140℃, 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, and Ce is added by 30% cerium-iron alloy; VD vacuum degassing, vacuum degree≤100Pa; deep vacuum treatment time≥13min; after breaking the vacuum, double-wire argon is opened, the double-wire argon is 200NL / min-400NL / min, 150m-200m of calcium wire is fed after the slag surface is boiling, and 30% cerium-iron alloy is added during the wire feeding process. The long water gap of the ladle adopts asbestos bowl and argon blowing protection pouring, uses tundish covering agent to prevent tundish liquid surface from being exposed, uses L7 protective slag supplied by Stoberg Company, liquid slag layer is 8mm-12mm, superheat is controlled to be 20-35℃, the section of the beam blank BB2 adopts automatic control of beam blank single water gap stopper, the drawing speed is controlled to be 0.7-0.8m / min, the water pressure of the crystallizer is greater than or equal to 0.8Mpa; the immersion water gap is inserted to a depth of 50-70mm, the secondary cooling adopts middle cooling water table; the casting blank slow cooling time is greater than 24 hours, and the lower laying and upper covering are used; Rolling process: step heating furnace, BD blooming, CCS universal rolling, step cooling bed cooling; wherein: The temperature of the preheating section is less than or equal to 900℃, the temperature of the first heating section is less than or equal to 1180℃, the temperature of the second heating section is 1150℃-1330℃, the temperature of the soaking section is 1200℃-1260℃, the furnace outlet temperature is greater than or equal to 1180℃, and the time in the furnace is 120min-220min; BD blooming, the blooming temperature is 1170℃-1200℃, the rolling pass is determined according to the final specification of the product, and the total reduction is greater than or equal to 50%; CCS universal rolling, the temperature of the last pass of the final rolling can be controlled to be 940℃-980℃; The product is cooled naturally on the cooling bed, and is straightened and sawed after the product temperature is lower than 100℃.

2. The rare earth low alloy high strength corrosion resistant low temperature low yield ratio hot-rolled H-beam for long-span steel structure according to claim 1, characterized in that: The mass percentage of the chemical composition includes: C 0.12%, Si 0.45%, Mn 1.23%, P 0.026%, S 0.007%, V 0.046%, Cr 0.27%, Ni 0.13%, Cu 0.28%, Ce 0.0018%, N 0.0065%, O 0.0023%, and the rest is Fe and impurities, and the mass fraction is 100%.

3. The rare earth low alloy high strength corrosion resistant low temperature low yield ratio hot-rolled H-beam for long-span steel structure according to claim 1, characterized in that: The mass percentage of the chemical composition includes: C 0.10%, Si 0.48%, Mn 1.29%, P 0.023%, S 0.005%, V 0.042%, Cr 0.26%, Ni 0.15%, Cu 0.27%, Ce 0.0023%, N 0.0058%, O 0.0018%, and the rest is Fe and impurities, and the mass fraction is 100%.

4. The rare earth low alloy high strength corrosion resistant low temperature low yield ratio hot-rolled H-beam for long-span steel structure according to claim 1, characterized in that: The mass percentage of the chemical composition includes: C 0.09%, Si 0.43%, Mn 1.25%, P 0.015%, S 0.006%, V 0.048%, Cr 0.29%, Ni 0.14%, Cu 0.26%, Ce 0.0015%, N 0.0052%, O 0.0019%, and the rest is Fe and impurities, and the mass fraction is 100%.

5. The rare earth low alloy high strength corrosion resistant low temperature resistant low yield ratio hot-rolled H-beam for long-span steel structure according to claim 1, characterized in that: The mass percentage of the chemical composition includes: C 0.13%, Si 0.41%, Mn 1.26%, P 0.028%, S 0.005%, V 0.043%, Cr 0.28%, Ni 0.14%, Cu 0.29%, Ce 0.0020%, N 0.0064%, O 0.0015%, and the rest is Fe and impurities, and the mass fraction is 100%. 6.The rare earth low alloy high strength corrosion resistant low temperature low yield ratio hot-rolled H-beam for long-span steel structure according to claim 1, characterized in that: Carbon equivalent CEV≤0.45%, atmospheric corrosion resistance index I≥6.0; performance meets: lower yield strength ReL≥380MPa, tensile strength Rm≥520MPa, yield ratio≤0.75, -60℃ impact toughness≥80J, elongation after fracture≥30%.

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