CN112410667A - Low-cost thick Q355E hot-rolled H-shaped steel and manufacturing method thereof - Google Patents
Low-cost thick Q355E hot-rolled H-shaped steel and manufacturing method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- B21B1/088—H- or I-sections
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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Abstract
The invention discloses low-cost thick Q355E hot-rolled H-shaped steel and a manufacturing method thereof, belonging to the technical field of steel smelting. The hot-rolled H-shaped steel comprises the following components in percentage by weight: c: 0.10 to 0.18 percent; si: 0.10-0.60%, Mn: 1.00% -1.60%; nb: 0.03 to 0.05 percent; ti: 0.01 to 0.015 percent; n: 0.003-0.005 percent, the balance of iron and other impurities, and the product range of Ti and N is 0.00004 percent to 0.0007 percent. In the production process, the total pass of the finish rolling of the universal machine is controlled to be 9-13, the rolling deformation of the last 5-3 passes in the finish rolling is controlled to be 7-8%, and the rolling deformation temperature is 880-930 ℃. The invention takes the thick and heavy Q335E hot-rolled H steel with the flange thickness of 50mm-80mm as the product target, provides the low-cost component design without adding Ni and V alloy elements, and obtains the hot-rolled H steel with high strength and high and low temperature toughness by matching with the control of the size of austenite grains after rough rolling.
Description
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to low-cost thick Q355E hot-rolled H-shaped steel and a manufacturing method thereof.
Background
Hot-rolled H-section steel is one of the steels for main structures, and plays an important role in the development of socioeconomic performance. With the economic development and scientific and technological progress, the construction of a series of large engineering structures such as high-rise buildings, ocean platforms, large all-weather railway traffic, large bridges and the like puts forward the requirements of large-scale, high-performance and greening on the new generation of hot-rolled H-shaped steel. However, the blank is still provided for the thick and heavy hot-rolled H-shaped steel products with high-performance flanges larger than 50mm in China at present, most of the heavy H-shaped steel is formed by welding thick plates, and the safety and the use convenience of the used materials are far inferior to those of the hot-rolled H-shaped steel. Therefore, the development of a new generation of heavy high-performance hot-rolled H-shaped steel has great significance for filling up the domestic blank, realizing the independent innovative production of the heavy hot-rolled H-shaped steel and improving the international competitiveness in the aspect of large engineering structures in China.
The heavy hot-rolled H-shaped steel for large-scale structures is limited by the size of a blank and the capability of a tool, and the deformation quantity among passes and accumulated is small, so that the crystal grain size is large, and the requirements of the strength, the plasticity and the low-temperature toughness of the material cannot be met. In order to obtain the required comprehensive properties, the noble metal element Ni is often required to be added to improve the low-temperature toughness of the steel, and the alloy element V is required to be added to improve the strength of the steel through dispersion strengthening, but the problems caused by the addition are that: (1) ni is a noble metal element and a strategic resource, and has short supply and high price; (2) v belongs to a rare resource in China, the price of V is always controlled by foreign capital, the price fluctuation is large, steel is influenced, and the control right of the product price is lost. Therefore, through the optimization and matching of component design and process, the development of the heavy Q355E hot-rolled H-shaped steel without adding a noble metal element Ni and an alloy element V is imperative to realize the green manufacturing of the product.
Currently, much work has been conducted on the research of hot-rolled H-section steel. For example, summer meng et al published in the journal of "the influence of controlled cooling after rolling on the mechanical properties of thick-walled hot-rolled H-section steel" in rolling, focused on controlled cooling after rolling, studied the influence of the cooling process of hot-rolled H-section steel Q345C steel with a flange thickness of 50mm on the properties, and did not consider that the increase of the cooling rate after rolling of heavy hot-rolled H-section steel inevitably leads to the increase of the structural property nonuniformity, and further influences the low-temperature toughness of heavy hot-rolled H-section steel. Wu Bao bridge et al published in the article of "influence of temperature controlled rolling on mechanical properties of vanadium microalloy hot rolled H-shaped steel" in journal of thermal processing technology, and the attention is mainly focused on the influence of V addition on the mechanical properties, which is different from the essence of not adding V in the invention. Chengding et al published in the journal of the institute of metallurgical technology and technology, Anhui province, the law of variation of low-temperature impact energy of thick-walled hot-rolled H-shaped steel along the width direction of the flange focuses on the uniformity of impact energy of the hot-rolled H-shaped steel with the flange thickness of less than 40mm, and the alloy components of the H-shaped steel contain 0.01 wt% of Ni, which is essentially different from the components provided by the invention. Guo Xighui et al, who published a "research on improving the impact properties of extra-thick Q275D hot-rolled H-section steel" in the journal of Steel research, focused on the reason why the low-temperature toughness was not satisfactory, and completely differed from the product grade and the content of interest of the high-performance thick and heavy hot-rolled H-section steel proposed by the present invention. From the condition of literature research, few researches are reported on hot-rolled H-shaped steel with flange thickness exceeding 50 mm. In addition, in foreign research on heavy hot rolled H-section steel, for example, hot rolled H-section steel products of JFE and Asilol Mitaler company, Ni is generally added as an alloy element. Therefore, from the comprehensive consideration of component design and flange thickness, research and development on low-cost (not containing alloy elements Ni and V) thick (flange thickness is 50-80mm) hot-rolled H-shaped steel which has both strength and low-temperature toughness are not reported at present.
Through search, the prior patent of the low-cost thick hot-rolled H-shaped steel which has both strength and low-temperature toughness is disclosed, for example, patent document CN103987866B entitled "high-strength extremely-thick H-shaped steel" discloses the component design of the extremely-thick H-shaped steel with the flange thickness of 100-150mm, the performance yield strength or 0.2% condition yield strength of the product is more than 450MPa, the tensile strength is more than 550MPa, and the component range is as follows: c: 0.09-0.15%, Si: 0.07 to 0.50%, Mn: 0.80-2.00%, Cu: 0.04-0.40%, Ni: 0.04-0.40%, V: 0.01-0.10%, Al: 0.005-0.040%, Ti: 0.001-0.025%, B: 0.0003-0.0012%, N: 0.001-0.0090%, O: 0.0005 to 0.0035%, further comprising Mo: 0.02-0.35% and Nb: at least one of 0.01 to 0.08%.
For another example, patent document CN107829031A entitled "a large section H-shaped steel and its production process" discloses a large section H-shaped steel and its production process, the chemical components of the material by weight percentage include: 0.08-0.13% of carbon, 0.15-0.35% of silicon, 1.25-1.45% of manganese, 0.10-0.20% of vanadium, less than or equal to 0.012% of nitrogen, less than or equal to 0.01% of phosphorus, less than or equal to 0.01% of sulfur, 0.03-0.05% of niobium, 0.03-0.05% of thallium, 0.03-0.05% of polonium, 0.02-0.04% of terbium, 0.01-0.02% of nickel, and the balance of iron and impurity elements.
For another example, patent CN104487604B discloses an "H-shaped steel and a manufacturing method thereof", wherein the material comprises the following chemical components by mass percent: c: 0.05 to 0.16%, Si: 0.01 to 0.50%, Mn: 0.80-2.00%, Ni: 0.05-0.50%, V: 0.01-0.20%, Al: 0.005-0.100%, Ti: 0.005-0.030%, N: 0.0010-0.0200%, O: 0.0001 to 0.0100%, Ca: 0.0003 to 0.0040%, Cr: 0-0.50%, Cu: 0 to 0.50%, Mo: 0-0.20%, Nb: 0 to 0.05 percent. The thickness of the flange is 100-150mm, and the attention point is that the flange is formed by oxide metallurgy, wherein the thickness of the flange is 100-5000 pieces/mm in number density per unit area2The oxide particles having a diameter of 0.005 to 2.0 μm in terms of equivalent circle diameter.
Further, as disclosed in patent application CN109715842B, "an H-shaped steel and a method for manufacturing the same". The chemical components are as follows: c: 0.050 to 0.160%, Si: 0.01-0.60%, Mn: 0.80-1.70%, Nb: 0.005-0.050%, V: 0.05 to 0.120%, Ti: 0.001-0.025%, N: 0.0001-0.0120%, Cr: 0-0.30%, Mo: 0-0.20%, Ni: 0-0.50%, Cu: 0-0.35%, W: 0-0.50%, Ca: 0-0.0050%, Zr: 0 to 0.0050%. The thickness of the flange is 20-140 mm, the tensile yield stress is 385-530 MPa, and the impact absorption energy at the temperature of minus 20 ℃ is more than 100J.
Disclosure of Invention
1. Problems to be solved
The invention takes the thick Q335E hot-rolled H steel with the flange thickness of 50mm-80mm as the product target, provides a low-cost component design scheme without adding Ni and V alloy elements, and obtains the thick Q335E hot-rolled H steel with high strength and high and low temperature toughness by matching with the control of controlling the size of austenite grains after rough rolling.
2. Technical scheme
In order to solve the above problems, the present invention adopts the following technical solutions.
The invention relates to low-cost thick Q355E hot-rolled H-shaped steel, which comprises the following components in percentage by weight: c: 0.10 to 0.18 percent; si: 0.10-0.60%, Mn: 1.00% -1.60%; nb: 0.03 to 0.05 percent; ti: 0.01 to 0.015 percent; n: 0.003-0.005 percent of the total weight of the alloy, and the balance of iron and other impurities, wherein the product range of Ti and N is 0.00004 percent to 0.0007 percent.
The components of the low-cost thick Q355E hot-rolled H-shaped steel provided by the invention are controlled as follows:
c: c is an element effective for strengthening steel, and the lower limit of the C content should be 0.10%; and when the content of C is more than 0.18%, the carbon equivalent CEV and the welding crack sensitivity index Pcm of the H-shaped steel can be obviously improved, the weldability of the H-shaped steel is reduced, and meanwhile, the low-temperature toughness of the H-shaped steel is also reduced, so that the content of C is controlled to be 0.10-0.18%.
Si: si is a deoxidizing element and also contributes to improvement of strength. Therefore, the lower limit of the Si content is set to 0.10%. On the other hand, if the Si content is more than 0.60%, high-temperature exfoliation is accelerated, toughness and lamellar tearing properties are deteriorated, and the surface quality of the steel is also adversely affected. Therefore, the upper limit of the Si content is set to 0.60%.
Mn: mn can improve the toughness and strength of the steel within a certain range. Therefore, the lower limit of the Mn content is set to 1.00%. On the other hand, if the Mn content is greater than 1.60%, macro-segregation is likely to occur, which causes significant reduction in toughness of the steel, and even delamination occurs, deteriorating the lamellar tear resistance, so the Mn content should be controlled in the range of 1.00% to 1.60%.
Nb: nb is used for precipitating enough NbC to form austenite grains which are prevented from growing by pinning effect, so that the effect of refining the austenite grains is realized. In order to obtain this effect, the lower limit of the Nb content is set to 0.03%; when the Nb content exceeds 0.05%, the internal fillet of the continuous casting beam blank is easy to crack, the surface quality of a final product is influenced, and the cost is not easy to control, so that the Nb content is controlled to be 0.03-0.05%.
Ti: ti is a main element for forming TiN, TiN is a high-temperature stable compound, and austenite grains in a high-temperature region are blocked from growing through TiN pinning so as to realize the effect of refining the austenite grains; meanwhile, the refined TiN can promote the precipitation of NbC and refine the size of the precipitated particles of the second phase, and in order to obtain the effect, the lower limit of the Ti content is set to be 0.010%, when the Ti content is too high, redundant Ti is dissolved in the steel, alloy waste is caused, the cost is increased, and the upper limit is set to be 0.015%.
N: n is a main element for forming TiN and is an element which is beneficial to the refinement of the structure and the precipitation strengthening, and N is also a key element for controlling the size of the precipitated TiN. Therefore, the lower limit of the N content is set to 0.003%. If the N content is more than 0.005%, the TiN particles become coarse, the low temperature toughness is lowered, the continuous casting surface cracks, and the strain aging of the steel material may be caused. Therefore, the upper limit of the N content is set to 0.005%.
As a further improvement of the invention, the flange thickness of the finished product of the H-shaped steel is 50-80mm, the yield strength is greater than 355MPa, the tensile strength is 450-590 MPa, the elongation after fracture is greater than 23%, and the impact toughness at minus 40 ℃ is greater than 120J.
As a further improvement of the invention, the grain size of the austenite inside the finished H-shaped steel is less than 10 microns.
A production method of low-cost heavy Q355E hot-rolled H-shaped steel comprises the following production steps: the method comprises the steps of molten steel smelting, continuous casting of a casting blank, heating of a heating furnace, rough rolling of a cogging mill, finish rolling of a universal machine and cooling of a cooling bed, wherein in the finish rolling step of the universal machine, the total pass of finish rolling of the universal machine is controlled to be 9-13, the rolling deformation of the last 5-3 passes in the finish rolling process is controlled to be 7-8%, and the rolling deformation temperature is 880-930 ℃.
As a further improvement of the invention, the rough rolling starting temperature of the cogging mill is not higher than 1050 ℃, the rolling deformation is 15-20%, the diameter of the roller is 1200-1400 mm, the rolling speed is 2.0-4.0 m/s, and the grain size of austenite in the rough-rolled piece is ensured to be less than 80 microns.
As a further improvement of the invention, the rolling temperature range is controlled to be 880-950 ℃ in the finish rolling process of the universal machine, the total rolling deformation is 50-60%, the diameter of a roller of the universal machine is 1200-1400 mm, and the rolling speed is 2.0-4.0 m/s.
As a further improvement of the invention, the rolling deformation of the last 2 nd pass in the finish rolling stage is controlled to be 15-20%, and the rolling deformation temperature is 880-930 ℃.
As a further improvement of the invention, the rolling deformation of the last 1 pass in the finish rolling stage is controlled to be 10-15%, and the rolling deformation temperature is 880-900 ℃.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel, the low-cost thick Q335E hot-rolled H-shaped steel product manufacturing is realized through the low-cost component design and optimization process matching, the domestic blank of the thick H-shaped steel is filled, the strategic resource of Ni is saved, and the green manufacturing of the product is realized.
(2) According to the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel, the range of the product of Ti and N is 0.00004% -0.0007%, the product of Ti and N is mainly used for controlling the size and distribution of TiN second-phase particles, the TiN second-phase particles are fine and are uniformly dispersed, and beyond the range, the size of the TiN second-phase particles is large, and the distribution in unit area is not uniform. The invention mainly uses the microalloying design of Nb, separates out and matches the second phase particles of titanium nitride TiN/niobium carbide NbC, heats at lower temperature, ensures that enough TiN and NbC second phase particles retain a part of residual particles in the heating process, and is used as a growing core for re-separating out the NbC in the cooling process, thereby accelerating the separation out of the second phase particles in the rough rolling process.
(3) According to the production method of the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel, the rolling starting temperature is controlled to be not higher than 1050 ℃ in the rough rolling process of the cogging mill, the rolling deformation is 15% -20%, the diameter of a roller is 1200-1400 mm, the rolling speed is 2.0-4.0 m/s, and the grain size of austenite in a rolled piece after rough rolling is ensured to be smaller than 80 micrometers. By utilizing the microalloying design of Ti and the rough rolling at a lower temperature of below 1050 ℃, the method ensures that NbC has thermodynamic driving force for separating out, so that the combination of TiN and NbC inhibits the growth of internal austenite grains, thereby controlling the size of the internal austenite grains; the lower rough rolling temperature is favorable for delaying the recrystallization of austenite, so that the rapid precipitation of NbC is realized through strain dislocation, the growth of austenite grains is inhibited, and the grain size of the austenite after rough rolling is ensured to be less than 80 microns.
(4) According to the production method of the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel, the rolling temperature range is controlled to be 880-950 ℃ in the finish rolling process of a universal machine, the total rolling deformation is 50-60%, the diameter of a roller of the universal machine is 1200-1400 mm, and the rolling speed is 2.0-4.0 m/s; wherein the finish rolling temperature of 880-950 ℃ ensures that NbC is fully separated out, inhibits the static recrystallization among the passes to realize the strain accumulation exceeding the austenite dynamic recrystallization critical strain, and realizes the grain ultra-fining.
(5) According to the production method of the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel, 9-13 rolling passes are performed by a universal machine, the rolling deformation of the last 5-3 passes in the finish rolling process is controlled to be 7% -8%, the rolling deformation temperature is controlled to be 880-930 ℃, austenite recrystallization is not generated in the rolling process, and the static recrystallization among the rolling passes is inhibited by using the second particles of TiN and NbC, so that strain accumulation is realized.
(6) According to the production method of the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel, the rolling deformation of the last 2 nd pass in the finish rolling stage is controlled to be 15% -20%, the rolling deformation temperature is 880-930 ℃, the strain accumulation is promoted to exceed the austenite dynamic recrystallization critical strain-induced austenite dynamic recrystallization, and the austenite grain ultra-fining is realized by regulating and controlling the austenite dynamic recrystallization critical strain-induced austenite dynamic recrystallization in the last 2 nd pass of the finish rolling.
(7) The production method of the low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel controls the rolling deformation of the last 1 pass in the finish rolling stage to be 10-15%, and the rolling deformation temperature to be 880-900 ℃. And rolling in a non-recrystallization region to realize strain accumulation in recrystallized austenite, regulating and controlling the size and the shape of the hot-rolled H-shaped steel, and promoting non-uniform nucleation of phase change by combining the grain size of ultrafine austenite and the strain accumulation so as to obtain a refined product structure, ensure that the grain size of the product is less than 10 microns and realize the performance requirement.
Drawings
FIG. 1 is a graph showing the variation of the precipitation volume fraction of NbC and the precipitation volume fraction of TiN in the low-temperature toughness hot-rolled H-shaped steel according to the rolling temperature:
wherein, the phi is expressed as the precipitation volume fraction of NbC; expressed as the precipitation volume fraction of TiN;
FIG. 2 is a schematic view showing the internal microstructure of the low temperature toughness hot rolled H-shaped steel of examples 1 to 5 in the present invention.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The present invention will be further described with reference to the following examples.
Example 1
The low-cost 460 MPa-grade excellent low-temperature toughness hot-rolled H-shaped steel comprises the following components in percentage by weight: c: 0.10 percent; si: 0.10%, Mn: 1.00 percent; nb: 0.03 percent; ti: 0.01 percent; n: 0.004%, and the balance of iron and other impurities, the embodiment realizes the production of the low-cost thick Q335E hot-rolled H-shaped steel by matching the low-cost component design and the optimized process, fills the domestic blank of the thick H-shaped steel, saves the strategic resource of Ni, and realizes the green production of the product.
In the embodiment, the range of the product of Ti and N is 0.00004% -0.0007%, the product of Ti and N is mainly used for controlling the size and distribution of TiN second phase particles, so that the fine and uniform dispersion distribution of the TiN second phase particles is ensured, and beyond the range, the size of the TiN second phase particles is large and the distribution in unit area is not uniform. In this example, mainly through Nb microalloying design, the second phase particles of titanium nitride TiN/niobium carbide NbC are separated out and matched, and heated at a lower temperature, so that sufficient TiN and NbC second phase particles are ensured to retain a part of residual particles (as shown in fig. 1) in the heating process, and are used as the growing core of NbC re-separation in the cooling process, thereby accelerating the separation of the second phase particles in the rough rolling process. Specifically, the product of Ti and N in this example is 0.00004%%.
The flange thickness of the finished product of the H-shaped steel is 50-80mm, the yield strength is greater than 355MPa, the tensile strength is 450-590 MPa, the elongation after fracture is greater than 23%, and the impact toughness at minus 40 ℃ is greater than 120J. Wherein the grain size of the austenite in the finished H-shaped steel is less than 10 microns. Specifically, the flange thickness of the finished product H-shaped steel in the embodiment is 50mm, the yield strength is 358MPa, the tensile strength is 450MPa, the elongation after fracture is 24%, and the impact toughness at minus 40 ℃ is 123J; the grain size of the austenite inside the finished H-shaped steel is 9.6 microns.
The production method of the low-cost thick Q355E hot-rolled H-shaped steel smelted by the molten steel with the components comprises the following production steps: smelting molten steel, continuously casting a casting blank, heating by a heating furnace, roughly rolling by a cogging mill, finely rolling by a universal machine, and cooling by a cooling bed, wherein the heating temperature in the heating furnace is less than 1200 ℃, the homogenization of alloy elements and austenite is ensured, and part of second particles are stored. In the embodiment, the initial rolling temperature is controlled to be not higher than 1050 ℃ in the rough rolling process of the cogging mill, the rolling deformation is 15-20%, the diameter of the roller is 1200-1400 mm, the rolling speed is 2.0-4.0 m/s, and the grain size of austenite in a rolled piece after rough rolling is ensured to be less than 80 microns. By utilizing the microalloying design of Ti and the rough rolling at a lower temperature of below 1050 ℃, the method ensures that NbC has thermodynamic driving force for separating out, so that the combination of TiN and NbC inhibits the growth of internal austenite grains, thereby controlling the size of the internal austenite grains; the lower rough rolling temperature is favorable for delaying the recrystallization of austenite, so that the rapid precipitation of NbC is realized through strain dislocation, the growth of austenite grains is inhibited, and the grain size of the austenite after rough rolling is ensured to be less than 80 microns. Specifically, in the rough rolling process of the cogging mill in the embodiment, the rolling start temperature is controlled to be 1040 ℃, the rolling deformation is controlled to be 15%, the diameter of the roller is 1200mm, and the rolling speed is 2.0 m/s.
In the embodiment, the rolling temperature range is controlled to be 880-950 ℃ in the finish rolling process of the universal machine, the total rolling deformation is 50-60%, the diameter of a roller of the universal machine is 1200-1400 mm, and the rolling speed is 2.0-4.0 m/s. The finish rolling temperature of 880-950 ℃ ensures that NbC is fully separated out, inhibits static recrystallization among passes to realize strain accumulation exceeding austenite dynamic recrystallization critical strain, and realizes grain ultra-fining. Specifically, in the present embodiment, the total rolling deformation is controlled to be 50% in the finish rolling process of the universal machine, the diameter of the roller of the universal machine is 1200mm, and the rolling speed is 2.0 m/s.
In the embodiment, the total pass of the finish rolling of the universal machine is 9-13, the rolling deformation of the last 5-3 passes in the finish rolling process is controlled to be 7% -8%, the rolling deformation temperature is 880-930 ℃, austenite recrystallization is not generated in the rolling process, and the static recrystallization among the rolling passes is inhibited by using the second particles of TiN and NbC, so that strain accumulation is realized. Specifically, in the embodiment, the total pass of the finish rolling of the universal machine is 9 passes, the rolling deformation of the last 5 to 3 passes in the finish rolling process is controlled to be 7%, and the rolling deformation temperature is 880 ℃.
In the embodiment, the rolling deformation of the last 2 nd pass in the finish rolling stage is controlled to be 15-20%, the rolling deformation temperature is controlled to be 880-930 ℃, the strain accumulation exceeds the austenite dynamic recrystallization critical strain induced austenite dynamic recrystallization, the austenite dynamic recrystallization critical strain induced austenite dynamic recrystallization is regulated and controlled in the last 2 nd pass of finish rolling, the austenite grain ultra-fining is realized, and the strain accumulation is realized by deformation in the last 1 pass of finish rolling. Specifically, in this example, the rolling deformation amount of the 2 nd pass from the last in the finish rolling stage was controlled to 15%, and the rolling deformation temperature was controlled to 900 ℃.
The rolling deformation of the last 1 pass in the finish rolling stage is controlled to be 10-15%, and the rolling deformation temperature is 880-900 ℃. Strain accumulation in recrystallized austenite is realized without rolling in a crystallization area, the size and the shape of the hot-rolled H-shaped steel are regulated, and meanwhile, the non-uniform nucleation of phase change is promoted by combining the grain size of ultrafine austenite and the strain accumulation, so that a refined product structure is obtained, the grain size of the product is ensured to be less than 10 microns, and the performance requirement is realized. Specifically, in this example, the rolling deformation amount of the last 1 pass in the finish rolling stage was controlled to 10%, and the rolling deformation temperature was 890 ℃.
The diameter range of TiN particles at the flange 1/6 and the web 1/4 of the finished hot-rolled H-shaped steel in the embodiment is 10 nm-100 nm, and the number density of particles in unit area is 200 particles/mm24000 pieces/mm2The diameter of NbC particles is 10 nm-100 nm, and the number density of particles per unit area is 200 particles/mm24000 pieces/mm2。
Example 2
The low-cost heavy Q355E hot-rolled H-shaped steel of the embodiment is basically the same as the H-shaped steel of the embodiment 1, and is different from the H-shaped steel of the embodiment in that the low-cost heavy Q355E hot-rolled H-shaped steel comprises the following components in percentage by weight: c: 0.18 percent; si: 0.60%, Mn: 1.60 percent; nb: 0.05 percent; ti: 0.015 percent; n: 0.003%, the balance being iron and other impurities, the product of Ti and N being 0.000045%. In the embodiment, the flange thickness of the finished product of the H-shaped steel is 80mm, the yield strength is 413MPa, the tensile strength is 590MPa, the elongation after fracture is 25 percent, and the impact toughness at minus 40 ℃ is 122J; the grain size of the austenite inside the finished H-shaped steel is 9.3 microns.
The basic flow of the production method of the low-cost heavy Q355E hot-rolled H-shaped steel in the embodiment is consistent with that in the embodiment 1, the difference is that the initial rolling temperature is controlled to be 1042 ℃ in the rough rolling process of the cogging mill, the rolling deformation is 20%, the diameter of a roller is 1400mm, and the rolling speed is 4.0 m/s.
In the embodiment, the total rolling deformation is controlled to be 60% in the finish rolling process of the universal machine, the diameter of a roller of the universal machine is 1400mm, and the rolling speed is 4.0 m/s.
In the embodiment, the total pass of the finish rolling of the universal machine is 13, the rolling deformation of the last 5 to 3 passes in the finish rolling process is controlled to be 8%, and the rolling deformation temperature is 930 ℃.
In this example, the rolling deformation of the last 2 nd pass in the finish rolling stage was controlled to 20%, and the rolling deformation temperature was controlled to 920 ℃.
In this example, the rolling deformation of the last 1 pass in the finish rolling stage was controlled to 15%, and the rolling deformation temperature was 900 ℃.
Example 3
The low-cost heavy Q355E hot-rolled H-shaped steel of the embodiment is basically the same as the H-shaped steel of the embodiment 1, and is different from the H-shaped steel of the embodiment in that the low-cost heavy Q355E hot-rolled H-shaped steel comprises the following components in percentage by weight: c: 0.13 percent; si: 0.42%, Mn: 1.45 percent; nb: 0.04 percent; ti: 0.012%; n: 0.004%, the rest is iron and other impurities, and the product of Ti and N is 0.000048%. In the embodiment, the flange thickness of the finished product of the H-shaped steel is 75mm, the yield strength is 413MPa, the tensile strength is 590MPa, the elongation after fracture is 25%, and the impact toughness at minus 40 ℃ is 122J; the grain size of the austenite inside the finished H-shaped steel is 8.9 microns.
The basic flow of the production method of the low-cost heavy Q355E hot-rolled H-shaped steel in the embodiment is consistent with that in the embodiment 1, the difference is that the initial rolling temperature is controlled to be 1030 ℃ in the rough rolling process of the cogging mill, the rolling deformation is 18%, the diameter of the roller is 1400mm, and the rolling speed is 3.0 m/s.
In the embodiment, the total rolling deformation is controlled to be 60% in the finish rolling process of the universal machine, the diameter of a roller of the universal machine is 1400mm, and the rolling speed is 3.5 m/s.
In the embodiment, the total pass of the finish rolling of the universal machine is 13, the rolling deformation of the last 5 to 3 passes in the finish rolling process is controlled to be 8%, and the rolling deformation temperature is 900 ℃.
In this example, the rolling deformation amount of the 2 nd pass from the last in the finish rolling stage was controlled to 18%, and the rolling deformation temperature was 890 ℃.
In this example, the rolling deformation of the last 1 pass in the finish rolling stage was controlled to 13%, and the rolling deformation temperature was 885 ℃.
Example 4
The low-cost heavy Q355E hot-rolled H-shaped steel of the embodiment is basically the same as the H-shaped steel of the embodiment 1, and is different from the H-shaped steel of the embodiment in that the low-cost heavy Q355E hot-rolled H-shaped steel comprises the following components in percentage by weight: c: 0.15 percent; si: 0.45%, Mn: 1.48 percent; nb: 0.04 percent; ti: 0.012%; n: 0.0045 percent, the balance of iron and other impurities, and the product of Ti and N is 0.000054 percent. In the embodiment, the flange thickness of the finished product of the H-shaped steel is 68mm, the yield strength is 378MPa, the tensile strength is 545MPa, the elongation after fracture is 26 percent, and the impact toughness at minus 40 ℃ is 162J; the grain size of the austenite inside the finished H-shaped steel is 8.7 microns.
The basic flow of the production method of the low-cost heavy Q355E hot-rolled H-shaped steel in the embodiment is consistent with that in the embodiment 1, the difference is that the initial rolling temperature is controlled to be 1010 ℃, the rolling deformation is 17%, the diameter of a roller is 1300mm, and the rolling speed is 3.5m/s in the rough rolling process of the cogging mill in the embodiment.
In the embodiment, the total rolling deformation is controlled to be 55% in the finish rolling process of the universal machine, the diameter of a roller of the universal machine is 1300mm, and the rolling speed is 3.5 m/s.
In the embodiment, the total pass of the finish rolling of the universal machine is 11, the rolling deformation of the last 5 to 3 passes in the finish rolling process is controlled to be 7%, and the rolling deformation temperature is 920 ℃.
In this example, the rolling deformation amount of the 2 nd pass from the last in the finish rolling stage was controlled to 17%, and the rolling deformation temperature was controlled to 900 ℃.
In this example, the rolling deformation amount of the last 1 pass in the finish rolling stage was controlled to 12%, and the rolling deformation temperature was 890 ℃.
Example 5
The low-cost heavy Q355E hot-rolled H-shaped steel of the embodiment is basically the same as the H-shaped steel of the embodiment 1, and is different from the H-shaped steel of the embodiment in that the low-cost heavy Q355E hot-rolled H-shaped steel comprises the following components in percentage by weight: c: 0.16 percent; si: 0.42%, Mn: 1.55 percent; nb: 0.05 percent; ti: 0.015 percent; n: 0.0045 percent, the balance of iron and other impurities, and the product of Ti and N is 0.0000675 percent. In the embodiment, the flange thickness of the finished product of the H-shaped steel is 76mm, the yield strength is 386MPa, the tensile strength is 543MPa, the elongation after fracture is 28 percent, and the impact toughness at minus 40 ℃ is 147J; the grain size of the austenite inside the finished H-shaped steel is 8.2 microns.
The basic flow of the production method of the low-cost heavy Q355E hot-rolled H-shaped steel in the embodiment is consistent with that in the embodiment 1, the difference is that the initial rolling temperature is controlled to be 1000 ℃, the rolling deformation is 16%, the diameter of a roller is 1350mm, and the rolling speed is 3m/s in the rough rolling process of the cogging mill in the embodiment.
In the embodiment, the total rolling deformation is controlled to be 58% in the finish rolling process of the universal machine, the diameter of a roller of the universal machine is 1400mm, and the rolling speed is 3 m/s.
In the embodiment, the total pass of the finish rolling of the universal machine is 12, the rolling deformation of the last 5 to 3 passes in the finish rolling process is controlled to be 8%, and the rolling deformation temperature is 910 ℃.
In this example, the rolling deformation amount of the 2 nd pass from the last in the finish rolling stage was controlled to 16%, and the rolling deformation temperature was 890 ℃.
In this example, the rolling deformation of the last 1 pass in the finish rolling stage was controlled to be 14%, and the rolling deformation temperature was 880 ℃.
The examples described herein are merely illustrative of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention, and various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall within the protection scope of the present invention.
Claims (9)
1. A low-cost massive Q355E hot-rolled H-shaped steel is characterized in that: comprises the following components in percentage by weight: c: 0.10 to 0.18 percent; si: 0.10-0.60%, Mn: 1.00% -1.60%; nb: 0.03 to 0.05 percent; ti: 0.01 to 0.015 percent; n: 0.003-0.005 percent of the total weight of the alloy, and the balance of iron and other impurities, wherein the product range of Ti and N is 0.00004 percent to 0.0007 percent.
2. The low-cost massive Q355E hot-rolled H-shaped steel as claimed in claim 1, wherein: the flange thickness of the finished product of the H-shaped steel is 50-80mm, the yield strength is greater than 355MPa, the tensile strength is 450-590 MPa, the elongation after fracture is greater than 23%, and the impact toughness at minus 40 ℃ is greater than 120J.
3. The low-cost massive Q355E hot-rolled H-shaped steel as claimed in claim 1, wherein: the grain size of the austenite in the finished H-shaped steel is less than 10 microns.
4. The low-cost massive Q355E hot-rolled H-shaped steel as claimed in claim 1, wherein: the diameter range of TiN particles at the flange 1/6 and the web 1/4 of the finished hot-rolled H-shaped steel is 10 nm-100 nm, and the number density of particles per unit area is 200 particles/mm24000 pieces/mm2The diameter of NbC particles is 10 nm-100 nm, and the number density of particles per unit area is 200 particles/mm24000 pieces/mm2 。
5. A method for producing low-cost heavy Q355E hot-rolled H-shaped steel by smelting molten steel with the composition of claim 1, which is characterized by comprising the following steps: comprises the following production steps: the method comprises the steps of molten steel smelting, continuous casting of a casting blank, heating of a heating furnace, rough rolling of a cogging mill, finish rolling of a universal machine and cooling of a cooling bed, wherein in the finish rolling step of the universal machine, the total pass of finish rolling of the universal machine is controlled to be 9-13, the rolling deformation of the last 5-3 passes in the finish rolling process is controlled to be 7-8%, and the rolling deformation temperature is 880-930 ℃.
6. A method of producing low cost heavy Q355E hot rolled H steel according to claim 5, wherein: wherein the rough rolling starting temperature of the cogging mill is not higher than 1050 ℃, the rolling deformation is 15-20%, the diameter of the roller is 1200-1400 mm, the rolling speed is 2.0-4.0 m/s, and the grain size of austenite in the rough-rolled piece is ensured to be less than 80 microns.
7. A method of producing low cost heavy Q355E hot rolled H steel according to claim 5, wherein: the rolling temperature range is controlled to be 880-950 ℃ in the finish rolling process of the universal machine, the total rolling deformation is 50-60%, the diameter of a roller of the universal machine is 1200-1400 mm, and the rolling speed is 2.0-4.0 m/s.
8. A method of producing a low cost heavy Q355E hot rolled H steel according to claim 7, wherein: the rolling deformation of the last 2 nd pass in the finish rolling stage is controlled to be 15-20%, and the rolling deformation temperature is controlled to be 880-930 ℃.
9. A method of producing a low cost massive Q355E hot rolled H steel according to claim 8, wherein: the rolling deformation of the last 1 pass in the finish rolling stage is controlled to be 10-15%, and the rolling deformation temperature is 880-900 ℃.
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