CN111748735A - Band steel with excellent low-temperature secondary processing performance and tensile strength of 390MPa and production method thereof - Google Patents
Band steel with excellent low-temperature secondary processing performance and tensile strength of 390MPa and production method thereof Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- 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
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- 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
- C21D8/0236—Cold rolling
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- 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
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Abstract
A steel strip with 390MPa tensile strength and excellent secondary processability at low temperature comprises the following components in percentage by weight: c: 0.0008 to 0.0028%, 0.07 to 0.1% of Si, Mn: 0.5-0.7%, P0.060-0.075%, S not more than 0.008%, Al: 0.02-0.05%, Ti: 0.02-0.06%, Nb: 0.006-0.022%, B: 0.0005-0.0015 percent of N, and less than or equal to 0.002 percent of N; the production steps are as follows: smeltingAnd casting into a blank; heating a casting blank; rough rolling; fine rolling; coiling; cold rolling after acid washing; carrying out continuous annealing treatment; slowly cooling; rapidly cooling; aging treatment; and (7) flattening. On the premise of ensuring the mechanical property, the invention ensures that the plastic strain ratio is 1.6-1.8 r90The strain hardening index is 0.18 to 0.19n90(ii) a The secondary processing brittleness transition temperature is stabilized at minus 60 to minus 70 ℃, the content of elements Ti and Nb is reduced, the cost is reduced by not less than 5 percent, the surface of the steel plate has no carbonized edge and bonding defects, and the steel plate is used for the automobile outer covering piece in a severe cold area.
Description
Technical Field
The invention relates to automobile steel and a production method thereof, in particular to strip steel with 390 MPa-level tensile strength and excellent low-temperature secondary processing performance and a production method thereof, which are particularly suitable for automobile outer covering high-strength steel applied in northern severe cold regions.
Background
With the development of light weight of automobiles, the proportion of cold-rolled high-strength steel in materials for automobile outer covers is increasing. Research shows that about 75% of oil consumption is related to the mass of the whole automobile, and the reduction of the mass of the automobile can effectively reduce the oil consumption and the emission. When the automobile quality is reduced by 10%, the oil consumption is reduced by 8%, and the emission is reduced by 4%. And the high-strength steel plate is adopted, and the original car body steel plate with the thickness of 1.0-1.2 mm can be thinned to 0.7-0.8 mm.
The secondary processing brittleness refers to a phenomenon that a steel plate is broken due to low-temperature impact in the secondary processing process after being subjected to punch forming. The susceptibility to secondary work brittleness is generally expressed in terms of ductile-brittle transition temperature. The IF steel is pure in steel quality, and solid-dissolved C and N are absent on grain boundaries, so that the bonding force between the grain boundaries is greatly reduced, and the interstitial-free steel plate is subjected to crystal fracture at low temperature and high-speed deformation, namely, the secondary processing brittleness phenomenon exists. In order to produce high-strength IF steel, P is added for solution strengthening treatment, and the phenomenon of secondary processing brittleness is more obvious because P is easy to segregate in grain boundaries, so how to effectively improve the secondary processing brittleness resistance of the material and reduce the ductile-brittle transition temperature of a steel plate so as to meet the development requirements of the automobile industry becomes the subject of research on some steel enterprises and research institutions at home and abroad.
The defects in the prior art are as follows: in some elements, because the C element is not matched and controlled with the Ti element and the Nb element, a large amount of FePTiNb composite precipitated phase is easily precipitated on a grain boundary during hot rolling, so that the secondary processing performance of the product is weakened, and the secondary processing embrittlement temperature is not lower than minus 60 ℃ or lower. More technologies in the process adopt a hood-type annealing furnace for annealing, and the hood-type annealing furnace for annealing has high cost, more importantly, surface defects such as carbonized edges, bonding and the like are easily generated on the surface, so that the surface quality requirements of an automobile outer covering part are not met, namely the defects that the surface is influenced by the macroscopic view and the surface is perfect are not allowed, such as the following searched patent documents:
the Chinese patent application No. 200610030716.1 discloses a manufacturing method for producing high-strength cold-rolled ultra-deep drawing steel plates by using a bell-type furnace, which comprises the following chemical components in percentage by mass: c is less than or equal to 0.006, Si is less than or equal to 0.30, Mn0.15-1.40, P is less than or equal to 0.08, S is less than or equal to 0.02, N is 0.001-0.005, Al is 0.03-0.06, B is 0.0003-0.002, and the addition amounts of Ti and Nb are respectively as follows: ti- (48/14) N (0.005-0.015), Nb- (93/12) C (0-0.03), and the balance Fe and inevitable impurities; smelting and casting blanks according to the components; heating at 1100-1250 ℃, rolling, and finishing rolling in a single-phase austenite area with the temperature of Ar3 or above; cold rolling, wherein the cold rolling reduction rate is more than 73%; annealing, namely annealing in a total hydrogen or nitrogen-hydrogen bell-type furnace at the temperature of 690-; and (5) flattening after annealing. The steel plate has the strength level of 390MPa, high elongation and r value and high secondary processing brittleness resistance, and the ductile-brittle transition temperature is lower than minus 40 ℃. However, the addition of Ti and Nb to the steel is not limited by S, and affects the ductile-brittle transition temperature; the cover type annealing process is adopted in the process, the cost is high, surface defects such as carbonized edges and bonding and the like are easily generated on the surface, the surface quality requirement of the automobile outer covering piece is not met, meanwhile, the ductile-brittle transition temperature of the steel is relatively high, the requirement of the automobile body for secondary processing brittleness resistance under the low-temperature environment below 60 ℃ below zero can not be met, the cost is high, more importantly, the surface defects such as the carbonized edges and the bonding and the like are easily generated on the surface, the surface quality requirement of the automobile outer covering piece is not met, and the defect that the surface is visually influenced by naked eyes to be perfect is not allowed.
Chinese patent application No. CN201710077294.1 discloses a 390MPa grade high-strength IF steel and a production method thereof, which comprises the working procedures of heating, hot rolling, cold rolling, continuous annealing and leveling; the high-strength IF steel comprises the following components in percentage by mass: less than or equal to 0.0060% of C, 0.10-0.50% of Si, less than or equal to 0.8% of Mn, 0.040-0.080% of P, less than or equal to 0.010% of S, 4-15 ppm of B, less than or equal to 35ppm of N, 0.020-0.060% of Alt, 0.04-0.09% of Ti, and the balance of Fe and inevitable impurities. The method adopts the P element with lower cost to perform solid solution strengthening to improve the strength grade of the ultra-low carbon steel, fixes interstitial atoms in the steel through the Ti element, ensures the non-timeliness of the steel plate and improves the stamping performance of the steel plate; the cold-rolled sheet for stamping with high tensile strength, high elongation and high r value is produced by controlling the processes of steel making, hot rolling, cold rolling, continuous annealing and leveling; the method has the characteristics of low implementation difficulty, low cost, stable production process, excellent finished product performance and stable performance. However, the patent does not describe secondary work brittleness resistance, the patent only fixes interstitial atoms by adding Ti element, and does not add Nb element, firstly Nb is effective for improving plane anisotropy, the steel added with Nb element has more excellent deep drawing performance, secondly, NbC precipitation has higher solubility than TiC precipitation in the annealing process, the higher the solubility is, the more solid solution carbon is increased, the segregation of phosphorus is reduced, and the toughness-brittleness transition temperature is more favorable to be reduced. Therefore, the patent only adds Ti element to fix interstitial atoms, and does not adopt a mode of Ti and Nb composite addition, and the ductile-brittle transition temperature is difficult to reach below minus 60 ℃.
Chinese patent application No. 201280064349.0 discloses a hot-dip plated high-strength steel sheet for press working, which has a tensile strength of 340MPa or more and less than 540MPa, is excellent in secondary work embrittlement resistance, low-temperature toughness of seam-welded portions, and corrosion resistance, and is applicable to fuel tanks, and which has a hot-dip plated layer formed on the surface of a cold-rolled steel sheet containing, in mass%, C: 0.0005 to 0.0050%, Si: 0.30% or less, Mn: 0.70 to 3.00%, P: 0.05% or less, Ti: 0.01 to 0.05%, Nb: 0.01 to 0.04%, B: 0.0005 to 0.0030%, S: 0.01% or less, Al: 0.01 to 0.30%, N: 0.0005 to 0.010% by mass, and the balance Fe and unavoidable impurities, [ Ti ] representing a Ti content (%), [ B ] representing a B content (%), [ P ] representing a P content (%), wherein TB defined by the following formula (A) is 0.03 to 0.06, and [ B ] and [ P ] satisfy the following formula (B). TB ═ 0.11- [ Ti ])/(ln ([ B ] × 10000)) (a); [ P ] < 10X [ B ] +0.03 (B). However, this steel is a hot-dip coated steel sheet, and the ductile-brittle transition temperature is-50 ℃ or higher, and cannot satisfy the requirement of the secondary work brittleness resistance of the vehicle body in a low-temperature environment.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides 390 MPa-level strip steel which can ensure the secondary processing brittle transition temperature to be below 60 ℃ below zero, reduces the cost by not less than 5% due to less Ti and Nb consumption, has no carbonized edge defect on the surface, can be used for secondary processing in a more severe cold area and has excellent low-temperature secondary processing performance, and a production method thereof.
The technical measures for realizing the purpose are as follows:
the strip steel with excellent low-temperature secondary processing performance and tensile strength of 390MPa comprises the following components in percentage by weight: c: 0.0008 to 0.0028%, 0.07 to 0.1% of Si, Mn: 0.5-0.7%, P0.060-0.075%, S not more than 0.008%, Al: 0.02-0.05%, Ti: 0.02-0.06%, Nb: 0.006-0.022%, B: 0.0005-0.0015%, N is less than or equal to 0.002%, and the balance of Fe and inevitable impurities; and satisfies the following conditions: ti = (48/14) N + (48/16) 1.5S + (48/12) 1.5C, Nb = (93/12) C.
Preferably: the weight percentage content of P is: 0.063-0.073%.
Preferably: the Mn content is 0.55-0.65% by weight.
Preferably: the weight percentage content of Ti is 0.030-0.050%.
Preferably: the Nb content is 0.010-0.018 wt%.
The method for producing the steel strip with excellent low-temperature secondary processing performance and 390 MPa-level tensile strength comprises the following steps:
1) adopting desulfurized molten iron, smelting the product according to preset components and casting the product into a blank;
2) heating a casting blank: the heating temperature is controlled to be 1240-1280 ℃, and the temperature is kept for 150-200 min;
3) carrying out rough rolling, and controlling the rough rolling temperature to be 1060-1090 ℃;
4) performing finish rolling, and controlling the finish rolling temperature to be 900-940 ℃;
5) coiling, wherein the coiling temperature is controlled to be 650-690 ℃;
6) carrying out cold rolling after conventional pickling, controlling the total cold rolling pressure to be 815-825 ℃, and controlling the annealing speed to be 180-250 m/min;
8) slowly cooling to 640-660 ℃ at a cooling speed of 6-11 ℃/s
9) Rapidly cooling to 440-460 ℃ at a cooling speed of 35-55 ℃/s;
10) performing overaging treatment, wherein the overaging temperature is controlled to be 430-370 ℃, the overaging time is controlled to be 3-5 min, and the final cooling temperature is 170-180 ℃;
11) leveling is carried out, and the leveling elongation is controlled to be 1.0-1.4%.
Preferably: the continuous annealing temperature is 815-820 ℃.
The mechanism and action of each component and main process in the invention
C: carbon is a basic element in steel, and is also the most economical and effective strengthening element, and C can be segregated in grain boundaries as solid solution C, thereby suppressing secondary work brittleness of steel. However, if the C content is too high, the deep drawability of the steel is deteriorated. At the same time, excessive TiC and NbC are formed, and the TiC and NbC suppress grain growth during annealing, thereby lowering the r value. Therefore, the C content is 0.0008 to 0.0028%.
Si: silicon is a solid solution strengthening element, is an economical strengthening element and has strong solid solution strengthening effect. With the increase of the silicon content, the strength of the steel is obviously improved, the plasticity and the secondary processing brittleness resistance are obviously reduced, and the cold formability and the welding performance are reduced. Meanwhile, Si element easily forms a compact oxide layer Mn on the surface of the steel plate2SiO4Seriously affecting the surface quality of the material. Therefore, the Si content is controlled to 0.07 to 0.1%.
Mn: manganese is a relatively economic strengthening element and is mainly used for adjusting the strength of steel, the strength can be improved by 60MPa when about 1% of Mn is added, and the addition amount needs to be determined according to the strength grade of a final product. The certain amount of Mn can lower the Ar3 transformation point, lower the finishing temperature of hot rolling, and refine ferrite grains of the hot rolled steel plate, thereby improving the low-temperature toughness. And if the Mn content is too high, the toughness of the steel sheet may be reduced. Therefore, in combination with the strength grade of the product, the manganese content is set to be 0.5-0.7%, and the Mn content is preferably 0.55-0.65% by weight.
P: phosphorus is a solid-solution strengthening element, and can greatly improve the strength and hardness of steel, but also obviously reduce the plasticity of the steel. The refining cost is increased due to the excessively low P content, and the control of the alloy cost is not facilitated due to the addition of other alloy elements. If the content of P is too high, P segregates in ferrite grain boundaries, and the grain boundary strength is lowered, thereby lowering the secondary work embrittlement resistance. Therefore, the content of P is controlled to be 0.060-0.075%, preferably 0.063-0.073% by weight, considering the contribution of P element to strength.
S: sulfur is a harmful element. S in steel reduces plasticity and toughness of steel by forming inclusions such as MnS, and thus, the S content should be reduced as much as possible, but is controlled to not more than 0.008% in consideration of manufacturing cost required for desulfurization.
Al: in the refining step, the steel is deoxidized to remove oxygen dissolved in the molten steel, and Al suppresses solid solution of nitrogen in ferrite to form AlN to suppress coarsening of crystal grains. If the Al content is too high, inclusions in the steel increase, and the toughness of the steel decreases. Therefore, the Al content is controlled to be 0.02-0.05%.
Ti and Nb: titanium and niobium are strong C, N-forming elements, and can fix interstitial atoms C and N in steel, form fine carbonitride of Ti and Nb, and suppress coarsening of crystal grains. When the contents of Ti and Nb are too high, Ti carbonitride precipitated by Ti element in grain boundary becomes coarse, the toughness of steel is reduced, FeTiP phase is easily generated, the solid solution strengthening of P is weakened, and Nb element precipitates NbC, so that the secondary processing brittleness of steel is reduced.
The precipitates and the sequence of Ti elements in the steel are as follows: TiN, TiS, Ti4C2S2And TiC; while the Nb element forms mainly NbC. Therefore, the addition amounts of Ti and Nb need to satisfy: ti = (48/14) N + (48/16) 1.5S + (48/12) 1.5C, Nb = (93/12) C. Therefore, the Ti content is controlled to be 0.020-0.060% in comprehensive consideration, and the Ti content is preferably 0.030-0.050% in weight percentage; the content of Nb is controlled to be 0.006-0.022%, and the content of Nb is preferably 0.010-0.018% by weight.
B: boron element inhibits P and S from segregating in the grain boundary, and effectively improves the secondary processing brittleness resistance of the steel. On the other hand, when the B content is too high, coarse BN is formed in the grain boundary, which lowers the secondary work embrittlement resistance of the steel and lowers the hot workability and toughness of the steel. Therefore, the content of B is controlled to 0.0005 to 0.0015%.
N: the formation of AlN by the nitrogen element suppresses the coarsening of crystal grains, but the N content is too high, and the toughness of the steel is lowered. The content of N should be reduced as much as possible, and considering the manufacturing cost, the content of N satisfies Ti = (48/14) N + (48/16) 1.5S + (48/12) 1.5C, and the content of N is reduced, thereby being beneficial to reducing the content of Ti and reducing the cost. Therefore, the N content is controlled to 0.002% or less.
According to the invention, the hot rolling coiling temperature is controlled to be 650-690 ℃, and the reduction of the coiling temperature is beneficial to obtaining more solid solution carbon and enhancing the grain boundary bonding strength, so that the ductile-brittle transition temperature is reduced, but the coiling temperature is too low, so that the precipitation of secondary phase particles in steel and the coarsening of matrix grains are not facilitated, and the deep drawing performance of a steel plate is reduced.
The invention adopts continuous annealing, on one hand, the surface quality control of the continuous annealing is better, mainly because the covering annealing is to stack the steel coils one by one, the surface quality defects such as bonding, carbonized edges and the like are easy to generate in the covering annealing furnace, and the continuous annealing is to spread the steel coils, and simultaneously the cleaning processes such as alkali cleaning, rinsing and the like are added on the surface of the steel plate, the surface of the steel coils is very smooth, the material of the invention is often used on the outer covering part of the automobile, and the requirement on the surface quality of the steel plate is higher. On the other hand, the continuous annealing has higher temperature than the cover annealing, and the high-temperature annealing can promote the formation of texture crystal grains of the matrix, increase the solid solubility of Ti and P in the matrix and hardly form a FeTiP phase. The heating time is short, the cooling speed is high, and the segregation of phosphorus in a grain boundary can be effectively reduced. In addition, the carbide is decomposed under high-temperature annealing, solid-solution carbon is increased, and the segregation of phosphorus is further reduced, so that the ductile-brittle transition temperature is reduced.
The continuous annealing temperature adopted by the invention is 815-825 ℃, and the annealing temperature is mainly increased, so that the recrystallization can be promoted, the deep drawing performance of the steel plate is improved, and the secondary processing brittleness resistance is also improved. Because the steel plate is mainly used for the automobile outer covering part, the thickness is often less than 1.0mm, if the annealing temperature is too high, quality defects such as thermal buckling, wrinkles and the like are easily generated in the continuous annealing furnace, and the normal passing of the steel plate in the continuous annealing furnace is seriously influenced. Comprehensively considering, the continuous annealing temperature is 815-825 ℃.
Compared with the prior art, the invention can ensure that the plastic strain ratio is 1.6-1.8 r under the premise of ensuring that the yield strength of the steel strip is 270-298 MPa, the tensile strength is 390-425 MPa and the elongation is more than or equal to 33 percent90The strain hardening index is 0.18 to 0.19n90(ii) a The brittle transition temperature of secondary processing is stabilized at minus 60 to minus 70 ℃; due to the reduction of the addition amount of Nb and Ti, the cost can be reduced by at least 5 percent compared with the prior art, the surface of the steel plate has no defects of carbonized edges and adhesion, and the steel plate can be used for preparing high-strength steel of the automobile outer covering part applied in a more severe cold area.
Drawings
FIG. 1 is a metallographic structure diagram (total body) of a steel of the present invention;
FIG. 2 is a phase diagram showing the complex precipitates of FePTiNb in which a large amount of FePTiNb precipitates at grain boundaries during hot rolling according to the prior art.
Detailed Description
The present invention is described in detail below:
table 1 is a list of values of chemical components of each example and comparative example of the present invention;
table 2 is a list of values of main process parameters in each example and comparative example of the present invention;
table 3 is a table of the performance tests and results of the examples and comparative examples of the present invention;
each example was produced according to the following procedure:
1) adopting desulfurized molten iron, smelting the product according to preset components and casting the product into a blank;
2) heating a casting blank: the heating temperature is controlled to be 1240-1280 ℃, and the temperature is kept for 150-200 min;
3) carrying out rough rolling, and controlling the rough rolling temperature to be 1060-1090 ℃;
4) performing finish rolling, and controlling the finish rolling temperature to be 900-940 ℃;
5) coiling, wherein the coiling temperature is controlled to be 650-690 ℃;
6) carrying out cold rolling after conventional pickling, controlling the total cold rolling pressure to be 815-825 ℃, and controlling the annealing speed to be 180-250 m/min;
8) slowly cooling to 640-660 ℃ at a cooling speed of 6-11 ℃/s
9) Rapidly cooling to 440-460 ℃ at a cooling speed of 35-55 ℃/s;
10) performing overaging treatment, wherein the overaging temperature is controlled to be 430-370 ℃, the overaging time is controlled to be 3-5 min, and the final cooling temperature is 170-180 ℃;
11) leveling is carried out, and the leveling elongation is controlled to be 1.0-1.4%.
TABLE 1 list of chemical compositions (wt%) of inventive and comparative examples
Description of the drawings: the values of Ti and Nb in table 1 were calculated by the formulae Ti = (48/14) N + (48/16) 1.5S + (48/12) 1.5C, and Nb = (93/12) C.
TABLE 2 List of the main process parameters of the examples of the invention and the comparative examples
TABLE 2
TABLE 3 Table of the results of mechanical Properties measurements of the examples of the invention and the comparative examples
As can be seen from Table 3, the ductile-brittle transition temperature of the steel plates with different finished product thicknesses is lower than-60 ℃, and the steel plates have higher strength and better deep drawing performance. As can be seen from the comparative examples, the ductile-brittle transition temperature of the comparative examples reaches more than-30 ℃, and a large amount of FePTiNb composite precipitated phase (as shown in figure 2) is precipitated on the grain boundary during hot rolling mainly due to the addition of excessive Ti or Nb, and the precipitates are irregular in shape and different in size, so that the ductile-brittle transition temperature of the steel plate is seriously influenced.
The above examples are merely preferred examples and are not intended to limit the embodiments of the present invention.
Claims (7)
1. The strip steel with excellent low-temperature secondary processing performance and tensile strength of 390MPa comprises the following components in percentage by weight: c: 0.0008 to 0.0028%, 0.07 to 0.1% of Si, Mn: 0.5-0.7%, P0.060-0.075%, S not more than 0.008%, Al: 0.02-0.05%, Ti: 0.02-0.06%, Nb: 0.006-0.022%, B: 0.0005-0.0015%, N is less than or equal to 0.002%, and the balance of Fe and inevitable impurities; and satisfies the following conditions: ti = (48/14) N + (48/16) 1.5S + (48/12) 1.5C, Nb = (93/12) C.
2. The steel strip of claim 1 having excellent secondary processability at low temperature and tensile strength of 390MPa grade, wherein: the weight percentage content of P is: 0.063-0.073%.
3. The steel strip of claim 1 having excellent secondary processability at low temperature and tensile strength of 390MPa grade, wherein: the Mn content is 0.55-0.65% by weight.
4. The steel strip of claim 1 having excellent secondary processability at low temperature and tensile strength of 390MPa grade, wherein: the weight percentage content of Ti is 0.030-0.050%.
5. The steel strip of claim 1 having excellent secondary processability at low temperature and tensile strength of 390MPa grade, wherein: the weight percentage content of Nb is 0.010-0.018.
6. The method for producing a steel strip of 390MPa class in tensile strength excellent in secondary workability at low temperatures according to claim 1, comprising the steps of:
1) adopting desulfurized molten iron, smelting the product according to preset components and casting the product into a blank;
2) heating a casting blank: the heating temperature is controlled to be 1240-1280 ℃, and the temperature is kept for 150-200 min;
3) carrying out rough rolling, and controlling the rough rolling temperature to be 1060-1090 ℃;
4) performing finish rolling, and controlling the finish rolling temperature to be 900-940 ℃;
5) coiling, wherein the coiling temperature is controlled to be 650-690 ℃;
6) carrying out cold rolling after conventional pickling, controlling the total cold rolling pressure to be 815-825 ℃, and controlling the annealing speed to be 180-250 m/min;
8) slowly cooling to 640-660 ℃ at a cooling speed of 6-11 ℃/s
9) Rapidly cooling to 440-460 ℃ at a cooling speed of 35-55 ℃/s;
10) performing overaging treatment, wherein the overaging temperature is controlled to be 430-370 ℃, the overaging time is controlled to be 3-5 min, and the final cooling temperature is 170-180 ℃;
11) leveling is carried out, and the leveling elongation is controlled to be 1.0-1.4%.
7. The method of claim 6, wherein the steel strip with 390MPa tensile strength has excellent secondary processability at low temperature, and is characterized in that: the continuous annealing temperature is 815-820 ℃.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112662942A (en) * | 2020-11-19 | 2021-04-16 | 南京钢铁股份有限公司 | Damping steel and preparation method thereof |
| CN113201632A (en) * | 2021-04-09 | 2021-08-03 | 唐山钢铁集团有限责任公司 | Production method of low-silicon phosphorus-added high-strength steel |
| CN114000060A (en) * | 2021-11-10 | 2022-02-01 | 山东钢铁集团日照有限公司 | Production method of high-strength low-temperature-impact-resistant phosphorus-containing high-strength steel strip |
| CN114411055A (en) * | 2021-12-31 | 2022-04-29 | 河钢股份有限公司 | 220 MPa-grade bake-hardening high-strength steel and production method thereof |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03257124A (en) * | 1990-03-06 | 1991-11-15 | Nippon Steel Corp | Production of cold rolled steel sheet for deep drawing having baking hardenability |
| JPH0770650A (en) * | 1993-09-02 | 1995-03-14 | Kawasaki Steel Corp | Production of cold rolled steel sheet extremely excellent in deep drawability |
| CN102199727A (en) * | 2011-05-17 | 2011-09-28 | 马鞍山钢铁股份有限公司 | 400MPa high-strength and high-forming-performance cold rolled steel plate and production method thereof |
| CN102719740A (en) * | 2012-03-29 | 2012-10-10 | 鞍钢股份有限公司 | Method for producing ultra-low carbon high-strength cold rolling sheet |
| CN105970094A (en) * | 2016-06-14 | 2016-09-28 | 武汉钢铁股份有限公司 | Production method for zinc electroplated baked hardened steel plate for automobile outer plate |
| CN107012397A (en) * | 2017-03-20 | 2017-08-04 | 唐山钢铁集团有限责任公司 | A kind of 340MPa grades of high-strength IF steel and its production method |
| CN111218609A (en) * | 2020-03-03 | 2020-06-02 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength automobile structural steel plate for continuous annealing, cold rolling and stamping and production method thereof |
-
2020
- 2020-06-22 CN CN202010571898.3A patent/CN111748735A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03257124A (en) * | 1990-03-06 | 1991-11-15 | Nippon Steel Corp | Production of cold rolled steel sheet for deep drawing having baking hardenability |
| JPH0770650A (en) * | 1993-09-02 | 1995-03-14 | Kawasaki Steel Corp | Production of cold rolled steel sheet extremely excellent in deep drawability |
| CN102199727A (en) * | 2011-05-17 | 2011-09-28 | 马鞍山钢铁股份有限公司 | 400MPa high-strength and high-forming-performance cold rolled steel plate and production method thereof |
| CN102719740A (en) * | 2012-03-29 | 2012-10-10 | 鞍钢股份有限公司 | Method for producing ultra-low carbon high-strength cold rolling sheet |
| CN105970094A (en) * | 2016-06-14 | 2016-09-28 | 武汉钢铁股份有限公司 | Production method for zinc electroplated baked hardened steel plate for automobile outer plate |
| CN107012397A (en) * | 2017-03-20 | 2017-08-04 | 唐山钢铁集团有限责任公司 | A kind of 340MPa grades of high-strength IF steel and its production method |
| CN111218609A (en) * | 2020-03-03 | 2020-06-02 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength automobile structural steel plate for continuous annealing, cold rolling and stamping and production method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 朱苗勇: "《现代冶金工艺学》", 31 December 2016 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112662942A (en) * | 2020-11-19 | 2021-04-16 | 南京钢铁股份有限公司 | Damping steel and preparation method thereof |
| CN113201632A (en) * | 2021-04-09 | 2021-08-03 | 唐山钢铁集团有限责任公司 | Production method of low-silicon phosphorus-added high-strength steel |
| CN114000060A (en) * | 2021-11-10 | 2022-02-01 | 山东钢铁集团日照有限公司 | Production method of high-strength low-temperature-impact-resistant phosphorus-containing high-strength steel strip |
| CN114411055A (en) * | 2021-12-31 | 2022-04-29 | 河钢股份有限公司 | 220 MPa-grade bake-hardening high-strength steel and production method thereof |
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