CN117165845A - 340 MPa-level alloying hot dip galvanized sheet for new energy automobile and preparation method thereof - Google Patents
340 MPa-level alloying hot dip galvanized sheet for new energy automobile and preparation method thereof Download PDFInfo
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- 238000005275 alloying Methods 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 103
- 239000010959 steel Substances 0.000 claims abstract description 103
- 238000005097 cold rolling Methods 0.000 claims abstract description 14
- 238000005246 galvanizing Methods 0.000 claims abstract description 13
- 238000005098 hot rolling Methods 0.000 claims abstract description 11
- 238000005266 casting Methods 0.000 claims abstract description 7
- 238000003723 Smelting Methods 0.000 claims abstract description 6
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- 229910000859 α-Fe Inorganic materials 0.000 claims description 21
- 238000010438 heat treatment Methods 0.000 claims description 20
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 18
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- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 15
- 239000011248 coating agent Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 9
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- 238000002788 crimping Methods 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 230000009467 reduction Effects 0.000 claims description 8
- 229910052725 zinc Inorganic materials 0.000 claims description 8
- 239000011701 zinc Substances 0.000 claims description 8
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 7
- 238000005482 strain hardening Methods 0.000 claims description 5
- 239000010960 cold rolled steel Substances 0.000 claims description 4
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Abstract
The invention provides a 340 MPa-level alloying hot dip galvanized sheet for a new energy automobile and a preparation method thereof, wherein the galvanized sheet comprises the following substrate components in percentage by weight: c:0.005% -0.007%, si:0.012 to 0.017 percent, mn:0.22 to 0.34 percent, P:0.03 to 0.05 percent of Nb:0.04 to 0.07 percent of Ti:0.003 to 0.005 percent, N is less than or equal to 0.003 percent, S is less than or equal to 0.005 percent, and the balance is Fe and unavoidable impurities, preferably, the content of C-Nb/7.736 in the hot dip galvanized outer plate is-5 to 15ppm. The preparation method comprises smelting, casting, hot rolling, pickling, cold rolling and hot galvanizing; the alloyed hot dip galvanized sheet produced by the invention is comparable with 340-grade BH steel and IF steel, has excellent comprehensive mechanical properties, room temperature aging resistance and the like, and has obvious performance advantages.
Description
Technical Field
The invention belongs to the field of metal materials, and particularly relates to a 340 MPa-level alloying hot dip galvanized sheet for a new energy automobile and a preparation method thereof.
Background
As an automotive panel with the largest steel amount for the whole vehicle, it is required that the steel sheet has both excellent formability and excellent dent resistance, and also has excellent natural aging resistance. However, the improvement of the formability of steel often contradicts with the improvement of the strength, and at the same time, the reduction of the dent resistance is caused. Currently, the most prominent varieties of steel for automotive panels are Interstitial Free (IF) steel and Bake Hardening (BH) steel. IF steel has excellent formability but poor dent resistance. BH steel exhibits excellent formability with low yield strength at the time of stamping, and has good dent resistance by improving the strength of a steel sheet after high-temperature painting and baking, but has a certain aging problem. For this reason, it is necessary to develop Gao Jiangqi panels having excellent formability, dent resistance and natural aging resistance.
The invention discloses a high tensile strength substrate, a hot dip galvanized automobile sheet and a manufacturing method thereof (CN 101353755A), wherein the chemical composition of the steel sheet is as follows (wt%): c:0.01 to 0.08 percent, si: less than or equal to 0.1 percent, mn:0.8 to 1.8 percent, cr: less than or equal to 1.0 percent, mo: less than or equal to 0.5 percent, T.Al: 0.02-0.08%, N: less than or equal to 0.006%, P+2S: less than or equal to 0.12 percent, less than or equal to 1.6 percent and less than or equal to 3.8 percent of Mn+3Cr+2Mo, fe: the balance. The component design of the steel plate adopts high carbon and adds noble metal elements such as Mn, cr, mo and the like, so that the alloy cost is greatly increased. Meanwhile, the structure is the original structure of pearlite and ferrite, the strength is higher, but the elongation is lower (32% -36%), and the stamping forming of the automobile plate is not facilitated.
The invention discloses an alloying hot dip galvanized steel with 390 MPa-level tensile strength for automobiles and a production method (CN 201510455209.1), wherein the steel plate comprises the following elemental components in percentage by weight: c:0.07 to 0.10 percent, si: less than or equal to 0.03 percent, mn:0.7 to 1.0 percent, P:0.010 to 0.025 percent, S is less than or equal to 0.010 percent, als: 0.020-0.070; the steel plate has high carbon content in component design, so that excessive solid solution C in the steel plate is easy to influence the natural aging resistance of the steel plate, and the addition of more solid solution strengthening elements Mn is not beneficial to the improvement of the forming performance of the steel plate.
Disclosure of Invention
The invention aims to overcome the problems and the shortcomings and provide a 340 MPa-grade alloyed hot-dip galvanized sheet with excellent formability, dent resistance and natural aging resistance for a new energy automobile and a preparation method thereof.
The invention aims at realizing the following steps:
the 340 MPa-level alloyed hot-dip galvanized sheet for the new energy automobile comprises the following galvanized sheet base plate components in percentage by weight: c:0.005% -0.007%, si:0.012 to 0.017 percent, mn:0.22 to 0.34 percent, P:0.03 to 0.05 percent of Nb:0.04 to 0.07 percent of Ti:0.003 to 0.005 percent, N is less than or equal to 0.003 percent, S is less than or equal to 0.005 percent, and the balance is Fe and unavoidable impurities, preferably, the C-Nb/7.736 in the hot galvanized sheet is-5 to 15ppm.
The substrate microstructure of the hot dip galvanized sheet comprises 80-90% of ferrite in the critical area, 10-20% of oriented ferrite, and Nb (C, N) and TiN which are dispersed. Preferably, the ferrite hardness of the intercritical region is 160-180HV, and the ferrite hardness of the oriented attached ferrite is 190-210 HV.
The yield strength of the hot dip galvanized sheet is 220-260MPa, the tensile strength is more than 340MPa, the elongation after fracture is more than 40%, the plastic strain ratio r is 2.2-2.4, the strain hardening index n is more than 0.25, and the bake hardening value BH2 is 40-60 MPa.
The iron weight percentage of the hot dip galvanized plate coating is 8% -10%.
The reason for designing the components of the invention is as follows:
c: c is the most important additive element in the invention, and plays a critical role in the bake-hardening value and the aging resistance of the steel sheet. When the C content is increased, the pearlite is easy to generate in the steel, the morphology and the distribution of the pearlite are difficult to control, the elongation, the r value and the n value of the steel are low, and the C content in the finished steel is too high, so that the aging problem is generated. In addition, when the content of the C element is too low, the steel-making cost is increased, and it is impossible to ensure that a certain amount of Nb-containing carbide is formed in the steel to make the strength of the steel too low, and at the same time, the bake hardening value of the steel sheet is too low. Therefore, in order to ensure the comprehensive mechanical property, the ageing resistance and the bake hardening value of the steel plate to be between 30 and 60MPa, the invention requires that the content of C element be between 0.005 and 0.007 percent and the content of C-Nb/7.736 be between-5 and 15ppm.
Si: si is one of the important elements in the invention, plays a role of solid solution strengthening, but Si with too high content reduces the toughness of steel and seriously affects the surface quality of galvanized plates. Therefore, the Si content of the present invention is required to be 0.012% to 0.017%.
Mn: mn element is one of important elements in the invention, and plays a role of solid solution strengthening. However, when the addition amount of Mn element is too high, the strength of the steel sheet is too high to affect the formability thereof. Therefore, the Mn content is required to be 0.22-0.34%.
P: the P element is one of important elements in the invention, and plays a role of solid solution strengthening. However, P is highly likely to be biased at grain boundaries, and when the P content is too high, secondary working embrittlement performance of the steel sheet is lowered. Meanwhile, excessive P element makes the strength of the steel plate too high to influence the forming performance of the steel plate. Therefore, the content of the P element is required to be 0.03% -0.05%.
Nb: nb element is one of the important elements of the present invention. Nb exists in steel mainly in a solid solution state and a precipitate form, wherein the dragging action of solid solution Nb atoms and the pinning action of a tiny Nb (C, N) precipitation relative interface can influence the recrystallization behavior of austenite, so that the final ferrite grains are thinned, and the strength of the steel plate is improved. In addition, precipitation of Nb (C, N) can regulate the solid solution C content of the steel plate, thereby affecting the bake hardening performance of the steel plate. Therefore, when Nb is added at less than 0.05%, the strength of the steel sheet cannot be ensured and the bake hardening value is easily excessively high. Meanwhile, adding an excessive amount of Nb element results in poor bake hardenability of the steel sheet and an increase in production cost. Therefore, the invention requires that the Nb content is 0.04-0.06%, and the content of C-Nb/7.736 is between-5 and 15ppm.
Ti: the Ti element is one of the important elements of the present invention. Ti and an impurity element N in steel form TiN, wherein the TiN is a compound with highest stability in the steel and can be separated out in molten steel, so that the TiN can play a role in solidifying N. However, when the Ti content is too high, the TiN size is excessively large, deteriorating the performance of the steel sheet. Meanwhile, excessive Ti content can precipitate FeTiP in the steel, prevent the steel plate from forming favorable texture in the recrystallization process, and reduce the r value of the steel plate. In addition, precipitation of the compound affects the solid solution strengthening effect of P, and reduces the strength of the steel sheet. Therefore, the Ti content is required to be 0.003% to 0.005% in the present invention.
N: n is a magazine element in steel, affects the aging resistance of the steel sheet, and is unfavorable for the improvement of r value. Therefore, the invention requires that the content of N element is less than or equal to 0.003 percent.
S: s is an impurity element in steel, and is easily reacted with Mn to form MnS, which deteriorates the performance of the steel sheet, so that the lower the content is, the better the steel sheet. Therefore, the invention requires that the S element content is less than or equal to 0.005%.
The second technical scheme of the invention is to provide a preparation method of the 340 MPa-level alloying hot galvanized sheet for the new energy automobile, which comprises smelting, casting, hot rolling, pickling, cold rolling and hot galvanizing;
1. smelting and casting: smelting, refining and casting into casting blanks according to the chemical components.
Temperature of middle ladle: the temperature of the tundish is set to 1500-1600 ℃ to ensure uniform tissues and components.
2. And (3) hot rolling: the heating temperature is 1250-1280 ℃, the furnace duration is more than 120min, the initial rolling temperature is 1060-1120 ℃, the final rolling temperature is 893-924 ℃, and the coiling temperature is 400-490 ℃. The thickness of the hot rolled coil is between 3 and 4 mm.
Heating temperature: since Ti is added to steel to fix N, the heating temperature is usually controlled to 1250 ℃ or higher in order to achieve a preferable effect of fixing N. Meanwhile, the temperature ensures that Nb (C, N) containing Nb compound is not precipitated in the steel, is favorable for uniform grain growth, and ensures that Ti (C, N) is precipitated in the subsequent recrystallization zone rolling stage to play a role in pinning grain boundaries and refining original austenite grains. In addition, the too high heating temperature can cause the excessive growth of the crystal grains, so that the effect of grain refinement cannot be obtained, and the energy waste is caused. The heating time is longer than 120min, and the alloy elements are ensured to be uniformly distributed. Therefore, the heating temperature is controlled to 1250-1280 ℃ and the duration is more than 120min.
Finishing temperature: the final rolling temperature is controlled between 893 ℃ and 924 ℃ and is higher than Ar3, so that deformation bands are formed in austenite grains during rolling, and more nucleation points are provided for subsequent ferrite transformation, so that the grains are refined.
Coiling temperature: when the crimping temperature is low, the supersaturation degree of the alloy element in the matrix phase is large, but the low temperature is unfavorable for the diffusion of the element, while the higher temperature is favorable for the diffusion of the element, but the precipitation driving force is low. The curl temperature is strongly related to the degree of carbonitride precipitation and thus has a direct effect on the final solid solution C content and BH value in the steel. In addition, the curling temperature is too high, so that iron scales on the surface of the steel plate are excessive, the dephosphorization cost is increased, and the surface quality of the steel plate is affected. Meanwhile, by adopting low-temperature coiling, laminar cooling or dislocation recovery from final rolling to coiling is effectively inhibited, more dislocations are promoted to be reserved in a matrix, deformation energy storage is improved, and recrystallization nucleation of subsequent annealing is promoted. Therefore, the invention prescribes the crimping temperature according to the element content relation of C and Nb, when the C-Nb/7.736 is between-5 and 5ppm, the crimping temperature is controlled between 400 and 450 ℃; when C-Nb/7.736 is between 5 and 15ppm, 5ppm is excluded, and the crimping temperature is controlled between 450 and 490 ℃.
3. Acid washing: and (3) pickling and removing iron scale oxides existing on the surface of the steel after hot rolling and coiling.
4. Cold rolling: the specification of the cold-rolled product is kept between 0.6 and 0.8mm, and the rolling reduction is controlled between 80 and 85 percent corresponding to the thickness of the target automobile panel of the product. The storage energy of cold rolling deformation is the driving force of annealing recrystallization, and sufficient rolling reduction can ensure the effect of ferrite recrystallization and refine ferrite grains. Meanwhile, with the increase of the cold rolling reduction, the steel plate mainly forms a strong gamma fiber texture with the texture components of {111} <110> and {111} <112>, and the oriented crystal grains have large storage energy and are easy to grow in the subsequent annealing process, so that the steel plate forms a strong {111}// ND texture, and the deep drawing performance is improved. However, too high a rolling reduction increases the load on the cold rolling mill, and the achievement of the target thickness cannot be ensured.
5. Hot galvanizing: the annealing temperature is 865-893 ℃ and the annealing time is 30-60 s before hot galvanizing; then slowly cooling the steel plate to 785-813 ℃ at a cooling rate of 10-16 ℃/s, and then cooling to 440-460 ℃ at a cooling rate of more than or equal to 30 ℃/s; then heating the steel plate to 450-460 ℃ and then entering a zinc pot, wherein the zinc plating process is 1-3 s, and then entering an alloying furnace for alloying treatment, wherein the alloying temperature is 473-530 ℃ and the alloying time is 18-23s; finally, the steel plate is cooled to room temperature. Wherein the key parameters are described as follows:
annealing temperature before hot galvanizing: the annealing stage can form a small amount of austenite in the steel to introduce oriented pig iron bodies in the slow cooling stage, while controlling the solid solution C content in the final steel by the re-dissolution of carbides. The excessive temperature and the large dissolution degree of carbide raise the content of solid solution C in steel, so that the BH value is too high and the problem of easy aging is caused. At the same time, too high an annealing temperature reduces the strength of the steel sheet while affecting the surface quality of the steel sheet. Too low an annealing temperature and low carbide dissolution make the final BH value too low. Therefore, according to the element content relation of C and Nb in the steel, when the content of C-Nb/7.736 is between-5 and 5ppm, the heating temperature is controlled to be 880 to 893 ℃; when the C-Nb/7.736 is 5-15 ppm, 5ppm is not included, and the heating temperature is controlled to be 865-880 ℃.
Annealing time before hot galvanizing: in order to ensure that the steel plate adjusts the content of solid solution C in the steel through the dissolution of Nb (C, N) at a certain annealing temperature, the content of solid solution C is too high due to overlong time, the size of ferrite recrystallization grains is uneven, and the content of solid solution C is too low due to too short time. Therefore, the annealing time before hot dip galvanizing is required to be 30 to 60 seconds.
Cooling rate: the slow cooling stage adopts the cooling speed of 10-16 ℃/s to reduce the temperature to 785-813 ℃, so that oriented auxiliary pig iron bodies can be formed in the steel plate, and the strength of the steel plate is improved. And then, the steel is rapidly cooled at a speed of more than or equal to 30 ℃ per second, so that a certain amount of solid solution C content in the steel can be ensured. Therefore, the invention requires the cooling speeds of the slow cooling stage and the fast cooling stage to be 10-16 ℃ per second and more than or equal to 30 ℃ per second respectively.
Temperature of steel sheet before galvanization: the temperature of the steel plate before galvanization is 450-460 ℃ to ensure that the steel plate does not generate the phenomenon of zinc condensation or zinc dragging in the subsequent galvanization process.
Alloying annealing temperature: the alloying annealing process is a process in which the iron content in the coating is continuously increased under the constant temperature environment. Research shows that when the iron content of the surface of the coating reaches 9%, the alloying process is completed, and the ideal compact delta phase (FeZn 10) is formed in the coating, so that the iron content of the coating is required to be controlled to be 8% -10%. To meet this requirement, the annealing temperature is controlled to 473-530 ℃. When the annealing temperature exceeds 530 ℃, fe3Zn10 (gamma phase) or Fe5Zn21 (gamma 1 phase) is easy to form in the coating, so that the anti-powdering performance of the coating and the surface quality of the galvanized sheet are deteriorated. Furthermore, the annealing temperature is too low to effectively complete the alloying. Therefore, the annealing temperature is controlled to 473 to 530 ℃.
Alloying annealing time: the annealing time is less than 18s and the iron content in the coating is too low to form a sufficient delta phase. If the annealing time is too long, a medium Γ1 phase is formed in the coating layer, so that the anti-powdering performance of the steel plate is deteriorated, and the surface quality of the steel plate is affected. Thus, the annealing time is controlled to 18-23s.
The final structure is as follows: 80-90% of ferrite (160-180 HV) +10-20% of oriented ferrite (190-210 HV) +Nb (C, N) and TiN which are dispersed and distributed.
The method can obtain the alloyed hot dip galvanized bake hardening steel plate with the yield strength of 220-260MPa, the tensile strength of more than 340MPa, the elongation after fracture of more than 40%, the plastic strain ratio r of 2.2-2.4, the strain hardening index n of more than 0.25 and the bake hardening value BH2 of 40-60 MPa.
The invention has the beneficial effects that:
(1) The 340-grade automobile plate adopts the component design of micro carbon (0.005% -0.007%), reduces the steelmaking cost compared with ultra-low carbon BH steel, and does not add high-cost alloy elements such as Mo, cr, V, sb, pb, thereby effectively controlling the alloy cost.
(2) According to the invention, different process systems are designed according to the addition amounts of C and Nb, and the final solid solution C content in the steel is effectively controlled through the coupling curling and annealing system, so that the bake hardening performance and the room temperature aging resistance of the steel plate are ensured.
(3) The 340-level alloyed hot-dip galvanized sheet introduces oriented pig iron body and dispersed precipitated phases on a ferrite base in a critical area, so that the yield strength is 220-260MPa, the tensile strength is more than 340MPa, the elongation after break is more than 40%, the plastic strain ratio r is 2.2-2.4, the strain hardening index n is more than 0.25, and the bake hardening value BH2 is 40-60 MPa. Compared with 340-grade BH steel and IF steel, the steel has excellent comprehensive mechanical properties, room temperature aging resistance and the like, and has obvious performance advantages.
Detailed Description
The invention is further illustrated by the following examples.
According to the component proportions of the technical scheme, smelting, casting, hot rolling, pickling, cold rolling and hot galvanizing are carried out;
(1) And (3) hot rolling:
the heating temperature is 1250-1280 ℃, the furnace duration is more than 120min, the initial rolling temperature is 1060-1120 ℃, the final rolling temperature is 893-924 ℃, and the coiling temperature is 400-490 ℃; the thickness of the hot rolled coil is 3-4 mm;
(2) Cold rolling: rolling reduction is controlled to 80% -85%; the thickness of the cold-rolled steel plate is 0.6-0.8 mm,
(3) Hot galvanizing:
a) Heating the cold-rolled steel plate to 865-893 ℃ and keeping the isothermal time for 30-60 s; slowly cooling the steel plate to 785-813 ℃ at a cooling speed of 10-16 ℃/s, and then cooling to 440-460 ℃ at a cooling speed of more than or equal to 30 ℃/s;
b) Heating the steel plate to 450-460 ℃ and then entering a zinc pot, wherein the zinc plating process is carried out for 1-3 s,
c) Alloying treatment is carried out on the steel plate, the alloying temperature is 473-530 ℃, and the alloying time is 18-23s; finally, the steel plate is cooled to room temperature.
Further; during the course of the reeling process, the reeling,
when the C-Nb/7.736 is-5 ppm, the crimping temperature is controlled at 400-450 ℃;
when C-Nb/7.736 is 5-15 ppm, 5ppm is excluded, and the crimping temperature is controlled at 450-490 ℃.
Further; in the course of the hot dip galvanizing process,
when the C-Nb/7.736 is between-5 and 5ppm, the heating temperature is controlled between 880 and 893 ℃;
when the C-Nb/7.736 is 5-15 ppm, 5ppm is not included, and the heating temperature is controlled to be 865-880 ℃.
The composition of the steel of the example of the invention is shown in Table 1. The main technological parameters of continuous casting, hot rolling and cold rolling of the steel of the embodiment of the invention are shown in table 2. The main technological parameters of the cold rolling annealing of the steel of the embodiment of the invention are shown in Table 3. The properties of the inventive example steels are shown in Table 4. The microstructure of the steel of the example of the invention is shown in Table 5.
TABLE 1 composition (wt%) of the inventive example steel
TABLE 2 main process parameters of continuous casting, hot rolling and cold rolling of the inventive example steel
| Examples | Heating temperature/. Degree.C | Initial rolling temperature/DEGC | Finishing temperature/°c | Coiling temperature/. Degree.C | Cold rolling reduction/% |
| 1 | 1261 | 1113 | 911 | 424 | 81 |
| 2 | 1252 | 1076 | 904 | 472 | 80 |
| 3 | 1271 | 1053 | 896 | 457 | 83 |
| 4 | 1243 | 1108 | 897 | 411 | 85 |
| 5 | 1278 | 1098 | 903 | 404 | 82 |
| 6 | 1256 | 1119 | 921 | 482 | 81 |
| 7 | 1267 | 1109 | 897 | 427 | 83 |
| 8 | 1256 | 1082 | 912 | 446 | 84 |
| 9 | 1278 | 1079 | 908 | 482 | 81 |
| 10 | 1269 | 1074 | 916 | 437 | 82 |
TABLE 3 Main Process parameters for Cold annealing of example steels according to the invention
TABLE 4 Properties of the inventive example Steel
TABLE 5 microstructure of inventive example steel
As can be seen from the above examples, the composition design and production process of the invention are adopted to prepare the alloy galvanized Gao Jiangqi vehicle sheet with yield strength of 220-260MPa, tensile strength of more than 340MPa, elongation after fracture of more than 40%, plastic strain ratio r of 2.2-2.4, strain hardening index n of more than 0.25 and bake hardening value BH2 of 40-60MPa, thereby realizing the high performance index of the alloy galvanized Gao Jiangqi vehicle sheet.
The present invention has been properly and fully described in the foregoing embodiments by way of example only, and not by way of limitation, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, any modification, equivalent substitution, improvement, etc. should be included in the scope of the invention, and the scope of the invention is defined by the claims.
Claims (9)
1. The 340 MPa-level alloying hot-dip galvanized sheet for the new energy automobile is characterized in that the galvanized sheet comprises the following substrate components in percentage by weight: c:0.005% -0.007%, si:0.012 to 0.017 percent, mn:0.22 to 0.34 percent, P:0.03 to 0.05 percent of Nb:0.04 to 0.07 percent of Ti:0.003 to 0.005 percent, N is less than or equal to 0.003 percent, S is less than or equal to 0.005 percent, and the balance is Fe and unavoidable impurities.
2. The 340 MPa-level alloying hot galvanized plate for a new energy automobile according to claim 1, wherein the C-Nb/7.736 in the hot galvanized outer plate is-5-15 ppm.
3. The 340 MPa-level alloying hot galvanized sheet for a new energy automobile according to claim 1, wherein the hot galvanized substrate microstructure is ferrite in a critical area, oriented auxiliary ferrite, and dispersed Nb (C, N) and TiN, wherein the volume percentage of each microstructure is 80-90% of ferrite in the critical area and 10-20% of oriented auxiliary ferrite.
4. The 340 MPa-grade alloyed hot-galvanized sheet for a new energy automobile according to claim 3, wherein the ferrite hardness of the critical zone is 160-180HV and the ferrite hardness of the oriented attached ferrite is 190-210 HV.
5. The 340 MPa-level alloyed hot-dip galvanized sheet for a new energy automobile according to claim 1, wherein the yield strength of the hot-dip galvanized sheet is 220-260MPa or more, the tensile strength is 340MPa or more, the elongation after break is 40% or more, the plastic strain ratio r is 2.2-2.4, the strain hardening index n is 0.25 or more, and the bake hardening value BH2 is 40-60 MPa.
6. The 340 MPa-grade alloying hot galvanized plate for the new energy automobile according to claim 1, wherein the mass percentage of iron in the hot galvanized plate coating is 8-10%.
7. A method for preparing a 340 MPa-grade alloyed hot-galvanized sheet for a new energy automobile according to any one of claims 1 to 6, comprising smelting, casting, hot rolling, pickling, cold rolling, hot galvanizing; the method is characterized in that:
(1) And (3) hot rolling:
the heating temperature is 1250-1280 ℃, the furnace duration is more than 120min, the initial rolling temperature is 1060-1120 ℃, the final rolling temperature is 893-924 ℃, and the coiling temperature is 400-490 ℃; the thickness of the hot rolled coil is 3-4 mm;
(2) Cold rolling: rolling reduction is controlled to 80% -85%; the thickness of the cold-rolled steel plate is 0.6-0.8 mm,
(3) Hot galvanizing:
a) Heating the cold-rolled steel plate to 865-893 ℃ and keeping the isothermal time for 30-60 s; slowly cooling the steel plate to 785-813 ℃ at a cooling speed of 10-16 ℃/s, and then cooling to 440-460 ℃ at a cooling speed of more than or equal to 30 ℃/s;
b) Heating the steel plate to 450-460 ℃ and then entering a zinc pot, wherein the zinc plating process is carried out for 1-3 s,
c) Alloying treatment is carried out on the steel plate, the alloying temperature is 473-530 ℃, and the alloying time is 18-23s; finally, the steel plate is cooled to room temperature.
8. The method for preparing 340MPa grade alloyed hot-galvanized sheet for new energy automobile according to claim 7, wherein in the hot rolling process,
when the C-Nb/7.736 is-5 ppm, the crimping temperature is controlled at 400-450 ℃;
when C-Nb/7.736 is 5-15 ppm, 5ppm is excluded, and the crimping temperature is controlled at 450-490 ℃.
9. The method for preparing the 340 MPa-grade alloyed hot-dip galvanized sheet for the new energy automobile according to claim 7, wherein in the hot dip galvanizing process,
when the C-Nb/7.736 is between-5 and 5ppm, the heating temperature is controlled between 880 and 893 ℃;
when the C-Nb/7.736 is 5-15 ppm, 5ppm is not included, and the heating temperature is controlled to be 865-880 ℃.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08176673A (en) * | 1994-12-21 | 1996-07-09 | Kawasaki Steel Corp | Production of steel sheet for can |
| CN1261408A (en) * | 1998-04-27 | 2000-07-26 | 日本钢管株式会社 | Cold rolled steel plate of excellent moldability, panel shape characteristics and denting resistance, molten zinc plated steel plate, and manufacture thereof |
| JP2000265244A (en) * | 1999-03-18 | 2000-09-26 | Sumitomo Metal Ind Ltd | Hot-dip galvanized steel sheet excellent in strength and ductility, and its manufacture |
| JP2002003996A (en) * | 2000-06-27 | 2002-01-09 | Sumitomo Metal Ind Ltd | High tensile steel sheet excellent in impact resistance and manufacturing method |
| CN101535519A (en) * | 2006-11-07 | 2009-09-16 | 新日本制铁株式会社 | High young's modulus steel plate and process for production thereof |
| CN107815591A (en) * | 2017-10-23 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot-dip galvanizing sheet steel and preparation method thereof |
| CN110629000A (en) * | 2018-06-25 | 2019-12-31 | 上海梅山钢铁股份有限公司 | Cold-rolled hot-dip galvanized steel sheet with yield strength of 280MPa and manufacturing method thereof |
-
2023
- 2023-04-28 CN CN202310476368.4A patent/CN117165845B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08176673A (en) * | 1994-12-21 | 1996-07-09 | Kawasaki Steel Corp | Production of steel sheet for can |
| CN1261408A (en) * | 1998-04-27 | 2000-07-26 | 日本钢管株式会社 | Cold rolled steel plate of excellent moldability, panel shape characteristics and denting resistance, molten zinc plated steel plate, and manufacture thereof |
| JP2000265244A (en) * | 1999-03-18 | 2000-09-26 | Sumitomo Metal Ind Ltd | Hot-dip galvanized steel sheet excellent in strength and ductility, and its manufacture |
| JP2002003996A (en) * | 2000-06-27 | 2002-01-09 | Sumitomo Metal Ind Ltd | High tensile steel sheet excellent in impact resistance and manufacturing method |
| CN101535519A (en) * | 2006-11-07 | 2009-09-16 | 新日本制铁株式会社 | High young's modulus steel plate and process for production thereof |
| CN107815591A (en) * | 2017-10-23 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot-dip galvanizing sheet steel and preparation method thereof |
| CN110629000A (en) * | 2018-06-25 | 2019-12-31 | 上海梅山钢铁股份有限公司 | Cold-rolled hot-dip galvanized steel sheet with yield strength of 280MPa and manufacturing method thereof |
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