CN113802060A - Low-cost steel plate for engineering structure and manufacturing method thereof - Google Patents
Low-cost steel plate for engineering structure and manufacturing method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 74
- 239000010959 steel Substances 0.000 title claims abstract description 74
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 31
- 238000005096 rolling process Methods 0.000 claims abstract description 43
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 8
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 8
- 239000000126 substance Substances 0.000 claims abstract description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910052742 iron Inorganic materials 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 15
- 230000009467 reduction Effects 0.000 claims description 14
- 229910000859 α-Fe Inorganic materials 0.000 claims description 13
- 238000009749 continuous casting Methods 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000007670 refining Methods 0.000 claims description 8
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 238000007872 degassing Methods 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 238000007664 blowing Methods 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- 238000003466 welding Methods 0.000 abstract description 8
- 238000001816 cooling Methods 0.000 abstract description 6
- 229910001566 austenite Inorganic materials 0.000 description 16
- 239000010955 niobium Substances 0.000 description 12
- 239000011572 manganese Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- 229910045601 alloy Inorganic materials 0.000 description 8
- 239000000956 alloy Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 230000009466 transformation Effects 0.000 description 7
- 238000005266 casting Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 230000007547 defect Effects 0.000 description 5
- 238000010899 nucleation Methods 0.000 description 5
- 230000006911 nucleation Effects 0.000 description 5
- 239000006104 solid solution Substances 0.000 description 5
- 229910052720 vanadium Inorganic materials 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910000746 Structural steel Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- RMLPZKRPSQVRAB-UHFFFAOYSA-N tris(3-methylphenyl) phosphate Chemical compound CC1=CC=CC(OP(=O)(OC=2C=C(C)C=CC=2)OC=2C=C(C)C=CC=2)=C1 RMLPZKRPSQVRAB-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
Abstract
A steel plate for low-cost engineering structure and a manufacturing method thereof are disclosed, wherein the steel comprises the following chemical components in percentage by weight: 0.10 to 0.138 percent of C, 0.20 to 0.39 percent of Si, 1.20 to 1.50 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.003 percent of S, 0 to 0.039 percent of Nb, 0.005 to 0.015 percent of Ti, 0.01 to 0.04 percent of Al, 0.32 to 0.38 percent of Ceq, and the balance of iron and inevitable impurities. The steel plate has the advantages of low cost, large thickness, high strength and toughness, high plasticity, low yield ratio, excellent welding performance and lamellar tearing resistance, does not need accelerated cooling after rolling, further improves the production efficiency and improves the uniformity of product performance.
Description
Technical Field
The invention relates to the field of metal materials, in particular to a steel plate for a low-cost engineering structure and a manufacturing method thereof.
Background
With the continuous development of engineering manufacturing technologies such as buildings, bridges and the like, the demand of steel structure building engineering is increasing day by day, the construction of projects such as super high-rise and large-span building structures, steel for super long bridges and the like is increasing, and in order to ensure the overall safety of the building structure projects, the steel plate for the engineering structures, which has high strength, good low-temperature toughness, welding performance, Z-direction lamellar tearing resistance and large thickness dimension, is in vigorous demand.
The high-performance steel plates with high strength and toughness, large thickness and the like are manufactured according to a conventional production method, higher alloy elements such as carbon, manganese, vanadium and the like are inevitably needed, the carbon equivalent is higher, the welding performance is poor, the alloy cost is higher, in addition, most structural steel needs to be controlled and cooled after being rolled, the production cost is further increased, the production efficiency is reduced, and the higher cost and the lower production efficiency are not beneficial to popularization and use of the engineering structural steel.
At present, some studies are made on steel for engineering structure at home and abroad, and partial patents and documents are found through search, but the content recorded in the steel is obviously different from the aspects of components, production methods, performances, product categories and the like in the technical scheme of the invention.
The relevant patents and documents retrieved are as follows:
related patent 1: the Chinese invention patent document with the patent application number of 201210584936.4 discloses 'a novel low-cost Q345GJC/D steel plate for high-rise buildings and a production method thereof', wherein the steel is strengthened by V-Cr, and the steel comprises the following chemical components in percentage by weight: 0.13-0.16% of C, 0.20-0.40% of Si, 0.90-1.10% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, 0.015-0.030% of Als, 0.020-0.030% of V and 0.10-0.20% of Cr0.10. The defects are as follows: the V, Cr composite adding mode is adopted, and the production cost is high.
Related patent 2: the Chinese invention patent document with the patent application number of 200810104298.5 discloses a steel plate for high-rise buildings and a production method thereof, the method only needs to add V microalloy elements on the basis of C-Mn steel, and adopts proper controlled rolling and controlled cooling to produce the steel plate for the high-rise buildings in a hot rolling state with good obdurability, low yield ratio, narrow yield point, lamellar tearing resistance and the like, and the defects are that: the content of V in the steel is 0.03-0.10%, the content of added vanadium is high, the production cost is high, cooling needs to be controlled, the production efficiency is low, and the performance is uneven.
Related patent No. 3: the Chinese invention patent document with the patent application number of 200710054569.6 discloses 'a high-strength steel plate for a large-thickness high-rise building structure and a production method thereof', which consists of the following chemical components in percentage by weight: less than or equal to 0.20 percent of C, less than or equal to 0.55 percent of Si, 1.00 to 1.70 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.70 percent of Ni, less than or equal to 0.70 percent of Cr, less than or equal to 0.20 percent of V, more than or equal to 0.015 percent of Nb, less than or equal to 0.20 percent of Ti, and 0.020 to 0.060 percent of Al, and the defects are as follows: the steel is added with Ni, Cr, V and other alloy elements, the electric furnace smelting-flat steel ingot casting process is adopted for steel making, and the normalizing process is adopted after rolling, so that the cost is higher.
In conclusion, the prior art has insufficient research on the steel for the low-cost engineering structure, and the yield ratio of the steel plate is too high, the performance of the whole plate is not uniform, the thickness specification of the rolled steel plate is small and the requirements of related engineering application cannot be met due to the fact that the alloy components are mostly reduced and the TMCP mode is adopted for rolling.
Disclosure of Invention
The invention aims to provide a low-cost steel plate for engineering structures and a manufacturing method thereof, the steel plate has the advantages of low cost, large thickness (the maximum thickness can reach 100mm), high strength and toughness, high plasticity, low yield ratio, excellent welding performance and lamellar tearing resistance, accelerated cooling is not needed after rolling, the production efficiency is further improved, and the uniformity of product performance is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a steel plate for low-cost engineering structure comprises the following chemical components in percentage by weight: 0.10 to 0.138 percent of C, 0.20 to 0.39 percent of Si, 1.20 to 1.50 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.003 percent of S, 0 to 0.039 percent of Nb, 0.005 to 0.015 percent of Ti, 0.01 to 0.04 percent of Al, 0.32 to 0.38 percent of Ceq, and the balance of iron and inevitable impurities.
The invention has the following design reasons:
c, the C can play a strengthening role through interstitial solid solution, can also form fine carbide precipitation through the action of alloy elements such as Nb and the like, and is precipitated before rolling deformation or austenite transformation, so that the growth of crystal grains is hindered, the nucleation rate is improved, and the structure is refined; meanwhile, dislocation movement can be hindered, the tensile strength is effectively improved, and the yield ratio is reduced, so that the content of C is not low; however, an increase in C has a bad influence on toughness, particularly low-temperature toughness; further, an increase in C increases the carbon equivalent of the steel, deteriorating the weldability of the steel sheet. Therefore, the C content cannot be too high, and it is considered that the C content is preferably controlled to 0.10% to 0.138% in the present invention.
Si is one of deoxidizing elements in steel, has strong solid solution strengthening effect, can purify ferrite, reduces the content of pearlite, is favorable for reducing the Bauschinger effect of a base material, and reduces the yield ratio of the steel plate. However, excessive Si lowers the toughness of the weld heat affected zone of the base metal, and deteriorates the toughness and weldability of the steel. Therefore, the content of Si in the invention is preferably controlled to be 0.20-0.39%.
Mn improves the strength of steel through solid solution strengthening, reduces austenite phase transition temperature, inhibits phase transition crystal grains of the steel plate from growing before accelerated cooling, plays a role in refining the crystal grains and improves the strength of the steel plate; however, if the Mn content is too high, ferrite transformation is easily inhibited, the yield strength of steel is affected, and reduction of yield ratio is not facilitated, and if the Mn content is too high, segregation is induced, the uniformity of steel sheet structure and the lamellar tearing property are deteriorated, and welding is not facilitated, and it is considered that it is preferable to control the Mn content to 1.20% to 1.50%.
P, S are harmful impurity elements in the invention, the lower the content, the better; in the invention, P is controlled to be less than or equal to 0.010 percent, and the increase of S content can promote the generation and growth of inclusions and deteriorate the low-temperature performance and the performance in the thickness direction, so that S is less than or equal to 0.003 percent.
Nb the effects of niobium in the present invention include (1) solid solution strengthening; (2) the crystal grains are precipitated in the rolling process, the crystal boundary is pinned, the nucleation is promoted, and the crystal grains are effectively refined, so that the strength is improved, and the toughness is improved; (3) the austenite phase transition temperature is reduced, and grains can be refined; however, the high Nb content deteriorates the toughness of the weld and the heat affected zone and increases the cost, and it is considered that the present invention is preferable to control the Nb content to 0% to 0.039%.
Ti can exert nitrogen fixation effect, form a precipitation phase mainly containing TiN, inhibit austenite grain growth under high temperature condition, and improve the toughness of a heat affected zone after welding. In addition, Ti is easy to appear in a form of interphase precipitation in the transformation process from austenite to ferrite due to low solid solubility, and the strength is improved. However, too much Ti lowers the toughness of the steel, and it is considered that the present invention is preferable to control the Ti content to 0.005% to 0.015%.
Al is a strong deoxidizing element and can be combined with N to form AlN, so that the effect of refining grains can be achieved, the low-temperature impact toughness is improved, and the brittle transition temperature of steel is reduced. AlN also has the effect of refining the structure. When the content of Al exceeds 0.040%, excessive alumina inclusions may reduce the cleanliness of the steel. If the Al content is too low, deoxidation is insufficient, and easily-oxidizable elements such as Ti and the like can form oxides, the invention considers that the Al content is preferably controlled to be 0.010-0.040%.
The final microstructure of the steel plate mainly comprises fine ferrite and pearlite structures, and the microstructure is uniform. Wherein, the volume percentage of the ferrite is 70 percent to 90 percent, and the average grain size of the ferrite is more than or equal to 10 grades.
The maximum thickness of the steel plate is 100 mm.
The yield strength of the steel plate is more than or equal to 345MPa, the tensile strength is more than or equal to 510MPa, the elongation after fracture is more than or equal to 28 percent, the yield ratio is less than or equal to 0.78, the Z-direction performance in the thickness direction is more than or equal to 50 percent, and the impact energy at minus 40 ℃ is more than or equal to 200J.
A manufacturing method of a steel plate for a low-cost engineering structure comprises the steps of molten iron pretreatment, converter smelting, external refining, continuous casting, rolling and straightening, and specifically comprises the following steps:
1) the shortest time for blowing argon in the LF refining treatment is 5 min; RH vacuum-pumping and degassing, and performing Ca treatment and micro Ti treatment on the molten steel; the shortest time of net circulation is 5 min; controlling the target superheat degree of the tundish at less than or equal to 30 ℃; protecting and pouring in the whole process, and putting into soft reduction; the refining and degassing treatment can effectively reduce impurity elements, properly reduce the treatment time of each part, further improve the production efficiency and reduce the cost, and the control of the pouring superheat degree and the soft reduction can effectively reduce the quality defects of casting blanks; the thickness of the continuous casting billet/the thickness of the finished steel plate is more than or equal to 3, and the grain size can be effectively controlled by increasing the compression ratio from the continuous casting billet to the finished steel plate.
2) The temperature of a heating section of the continuous casting billet is 1160-1210 ℃, and the temperature of a soaking section is 1140-1180 ℃; the heating process can meet the solid solution of the alloy, particularly the Nb element, and simultaneously, the heating temperature is properly reduced, so that the excessive growth of austenite grains is prevented, the temperature rise time is shortened, and the production efficiency is improved.
3) The initial rolling temperature of rough rolling is 1050-1085 ℃, the final rolling temperature of rough rolling is 980-1030 ℃, the single-pass reduction in the rough rolling stage is more than or equal to 15%, the reduction in each pass of at least the last 2 passes is more than or equal to 17%, the pass interval is not more than 15s, and the accumulated reduction rate in the rough rolling stage is more than or equal to 50%; the rolling temperature and the deformation process in the rough rolling stage ensure that austenite grains are recrystallized and the grains are inhibited from growing up, the equipment load of steel for the engineering structure can be reduced by adopting a large reduction and short interval process in the rough rolling end section, and the recrystallization of austenite is promoted by utilizing the deformation superposition effect of multi-pass large reduction rate, so that the grain refining target is reached, and the method is suitable for producing the steel plate for the engineering structure.
4) The thickness of the intermediate temperature-waiting blank is 1.5 t-6 t, wherein t is the thickness of a finished steel plate, the rolling temperature of the finish rolling is 800-839 ℃, the rolling temperature of the finish rolling is 740-780 ℃, and the single-pass deformation rate is not lower than 10%; the thickness of the intermediate blank to be heated can meet the requirement of accumulation of austenite deformation and deformation energy in a non-recrystallization region, and can ensure that enough deformation rate is obtained in the rough rolling stage under the condition of certain thickness of the original casting blank, so that the purpose of grain refinement is achieved; the austenite is further refined by the single-pass large reduction in the non-recrystallization region, so that the internal fine defects of the casting blank are overcome, and the reduction rate of the section in the thickness direction is increased; the low finish rolling temperature promotes the accumulation of austenite transformation energy and the induced precipitation of fine precipitated phases of Nb and Ti, and increases nucleation positions; sufficient deformation near the transformation point temperature at the final stage of finish rolling is beneficial to the generation of fine ferrite, the effective grain size can be reduced, and the low-temperature toughness is obviously improved.
Compared with the prior art, the invention has the beneficial effects that:
1) the components of the invention improve the toughness of the material through low C and low Mn design, utilize Nb and Ti elements to inhibit the growth of austenite grains and refine the grains by promoting nucleation in the austenite transformation process, control the thickness core structure of the steel plate and improve the uniformity of the structure; the matching problem of technical indexes such as high strength, low yield ratio, low temperature toughness and the like of the steel for the engineering structure is solved by matching with a corresponding unique production process.
2) The Ceq of the steel plate is only 0.32-0.38, the welding performance is excellent, and the processing efficiency of the member can be improved.
3) The invention has no precious alloy elements, reduces the alloy cost and further improves the plasticity and toughness of the steel plate.
4) According to the smelting and continuous casting process scheme, on one hand, the relevant process time is optimized and shortened, the production efficiency is further improved, the low-phosphorus and low-carbon control is realized, and the quality of a casting blank is improved, so that the performance of a final product is improved.
5) The invention adopts a two-stage low-temperature rolling process to obtain a complex phase structure consisting of ferrite and pearlite with a proper proportion, the average grain size of the ferrite is more than or equal to 10 grade, and the strength and the ductility and toughness can be optimally matched by properly controlling the content proportion of the ferrite and the pearlite, thereby achieving the purposes of improving the strength and reducing the yield ratio.
6) The invention is a manufacturing method of two-stage rolling, does not need subsequent accelerated cooling and heat treatment, has simple working procedures and uniform head and tail performance of the steel plate, and can further improve the production efficiency.
7) The steel plate for the low-cost engineering structure has the maximum thickness of 100mm, the yield strength of more than or equal to 345MPa, the tensile strength of more than or equal to 510MPa, the elongation after fracture of more than or equal to 28 percent, the yield ratio of less than or equal to 0.78, the Z-direction performance of more than or equal to 50 percent in the thickness direction, the impact energy of more than or equal to 200J at the temperature of minus 40 ℃, and meets the requirements of steel for the ultra-high-rise and large-thickness engineering structure under the low-temperature condition of 0-minus 40 ℃.
Drawings
FIG. 1 is a metallographic structure photograph of example 5.
Detailed Description
The following examples are intended to illustrate the invention in detail, and are intended to be a general description of the invention, and not to limit the invention.
According to the low-cost steel plate for the engineering structure and the manufacturing method thereof, the welding performance and toughness of the material are improved through low C and low Mn in component design, the grains are refined by utilizing Nb and Ti elements to inhibit the growth of austenite grains and promoting nucleation in the austenite transformation process, the thickness core structure of the steel plate is controlled, and the uniformity of the structure is improved; meanwhile, the Nb is utilized to inhibit austenite recrystallization, so that the rolling pass reduction rate is increased, the rolling temperature is reduced, and the grain refinement is promoted. And the corresponding production processes of smelting, heating, rolling and the like are matched to obtain the comprehensive properties of low cost, large thickness, low yield ratio, excellent weldability, low-temperature toughness and the like and ideal microstructure.
The chemical compositions of the examples of the invention are shown in table 1; the smelting continuous casting and slab heating processes of the corresponding embodiments are shown in table 2; the rough rolling process of the corresponding example is shown in table 3; the finish rolling process of the corresponding example is shown in Table 4; the properties and microstructure proportions of the corresponding examples are shown in Table 5.
TABLE 1 chemical composition wt% of the inventive examples
Table 2 continuous casting and billet heating process according to the embodiment of the present invention
| Examples | Degree of superheat of casting, deg.C | Thickness of continuous casting blank/thickness of finished product | Heating zone temperature/. degree.C | Soaking temperature/. degree.C |
| 1 | 13 | 20 | 1162-1168 | 1140-1148 |
| 2 | 19 | 18 | 1173-1179 | 1142-1149 |
| 3 | 21 | 12.5 | 1165-1207 | 1158-1167 |
| 4 | 18 | 6.3 | 1192-1205 | 1164-1176 |
| 5 | 22 | 5.0 | 1204-1210 | 1172-1179 |
| 6 | 19 | 4.6 | 1198-1208 | 1144-1149 |
| 7 | 25 | 3.8 | 1186-1194 | 1165-1177 |
| 8 | 17 | 3.0 | 1201-1209 | 1267-1179 |
Table 3 rough rolling process of the present invention example
TABLE 4 finish rolling process of examples of the present invention
TABLE 5 Properties and ferrite volume fractions of examples of the invention
Claims (7)
1. The steel plate for the low-cost engineering structure is characterized in that the steel comprises the following chemical components in percentage by weight: 0.10 to 0.138 percent of C, 0.20 to 0.39 percent of Si, 1.20 to 1.50 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.003 percent of S, 0 to 0.039 percent of Nb, 0.005 to 0.015 percent of Ti, 0.01 to 0.04 percent of Al, 0.32 to 0.38 percent of Ceq, and the balance of iron and inevitable impurities.
2. The steel plate for low-cost engineering and structural use according to claim 1, wherein the volume percentage of ferrite in the steel plate is 70-90%, and the average grain size of ferrite is not less than 10 grade.
3. A steel plate for low cost engineering structure according to claim 1, wherein the maximum thickness of the steel plate is 100 mm.
4. The steel plate for low-cost engineering structures as claimed in claim 1, wherein the steel plate has a yield strength of 345MPa or more, a tensile strength of 510MPa or more, a post-fracture elongation of 28% or more, a yield ratio of 0.78 or less, a thickness direction Z-direction performance of 50% or more, and a-40 ℃ impact energy of 200J or more.
5. A method for manufacturing a steel plate for low-cost engineering structures according to any one of claims 1 to 4, comprising the steps of:
1) the temperature of a heating section of the continuous casting billet is 1160-1210 ℃, and the temperature of a soaking section is 1140-1180 ℃;
2) the initial rolling temperature of rough rolling is 1050-1085 ℃, the final rolling temperature of rough rolling is 980-1030 ℃, the single-pass reduction in the rough rolling stage is more than or equal to 15%, the reduction in each pass of at least the last 2 passes is more than or equal to 17%, the pass interval is not more than 15s, and the accumulated reduction rate in the rough rolling stage is more than or equal to 50%;
3) the thickness of the intermediate temperature-waiting blank is 1.5 t-6 t, wherein t is the thickness of a finished steel plate, the rolling temperature of the finish rolling is 800-839 ℃, the rolling temperature of the finish rolling is 740-780 ℃, and the single-pass deformation rate is not lower than 10%.
6. The method for manufacturing a steel plate for low-cost engineering structure according to claim 5, wherein the thickness of the continuous casting slab/the thickness of the finished steel plate is not less than 3.
7. The method for manufacturing a steel plate for low-cost engineering structures according to claim 5, wherein in the LF refining treatment, the minimum time for net blowing argon is 5 min; RH vacuum-pumping and degassing, and performing Ca treatment and micro Ti treatment on the molten steel; the shortest time of net circulation is 5 min; the target superheat degree of the tundish is controlled at the temperature of less than or equal to 30 ℃.
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Application publication date: 20211217 |