CN104988417A - Corrosion-resistant structure steel plate for bridge with yield strength being 485MPa and production method thereof - Google Patents
Corrosion-resistant structure steel plate for bridge with yield strength being 485MPa and production method thereof Download PDFInfo
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- 238000005260 corrosion Methods 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
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- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 15
- 229910052802 copper Inorganic materials 0.000 claims abstract description 11
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 9
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- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 9
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 8
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- 238000005096 rolling process Methods 0.000 claims description 39
- 229910000746 Structural steel Inorganic materials 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 15
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- 238000005266 casting Methods 0.000 claims description 6
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- 238000003723 Smelting Methods 0.000 claims description 5
- 229910045601 alloy Inorganic materials 0.000 claims description 4
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Abstract
The invention discloses a corrosion-resistant structure steel plate for a bridge with the yield strength being 485MPa and a production method thereof. The structure steel plate comprises the following components in percent by weight: 0.060 percent to 0.090 percent of C, 0.30 percent to 0.50 percent of Si, 1.10 percent to 1.35 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.025 percent to 0.045 percent of Nb, 0.040 percent to 0.070 percent of V, 0.25 percent to 0.45 percent of Ni, 0.25 percent to 0.40 percent of Cu, 0.45 percent to 0.65 percent of Cr, 0.020 percent to 0.080 percent of Mo, and the balance of Fe and unavoidable impurities, the sensitive composition of welding cracks meets the formula Pcm is less than or equal to 0.22, the corrosion-resistance coefficient I is more than or equal to 6.7, the carbon equivalent CEV is less than or equal to 0.49, and Nb/Mn is equal to 0.02 to 0.04. The structure steel plate designed and produced by the process has good corrosion resistance; protective paint or a corrosion inhibitor does not need to be coated on the surface of the steel bridge, so that the cost for manufacture and maintenance is greatly reduced; the welding performance of the steel plate is improved by strictly controlling the carbon equivalent CEV to be less than or equal to 0.49 and Pcm to be less than or equal to 0.22; after welding, no preheating is needed, or the preheating temperature is not higher than 50DEG C; and after welding, heat treatment is not needed, so that the welding efficiency and the welding quality are greatly improved.
Description
Technical Field
The invention belongs to the technical field of structural steel for bridges in metallurgical industry, and particularly relates to a corrosion-resistant structural steel plate for bridges with a yield strength of 485MPa and a manufacturing method thereof.
Background
In recent years, with the rapid development of traffic construction, a large number of railway and highway bridges are newly built in China, and the span, the operation load, the driving speed and the like of the bridges are gradually improved, so that higher technical requirements are provided for bridge steel, and the bridge steel is required to have excellent mechanical properties and welding properties and good corrosion resistance.
At present, the main measure of corrosion protection of domestic bridge steel is to coat a layer or a corrosion inhibitor on the surface of a steel bridge, and due to factors such as large span, complex structure and the like of the bridge, the coating process is complex and the cost is high, meanwhile, the service life of the coating is generally 10-15 years, and the service time of a common railway bridge is more than 70 years, so that the bridge needs to be recoated for many times in the subsequent use process, thereby greatly increasing the maintenance cost of the bridge; meanwhile, the use of a large amount of paint and coating is also contrary to the aim of resource-saving and environment-friendly social development. Therefore, the steel with good corrosion resistance is used, so that the step of painting paint can be omitted in the bridge construction process, the cost is reduced, and simultaneously, the huge cost required for maintaining the bridge in the future is reduced.
With the rapid development of bridge steel, domestic bridge steel is more and more patented, but most of bridge steel is low in yield strength and poor in corrosion resistance or has no corrosion resistance, and a small number of patented patents relate to the production of high-strength bridge steel.
Through retrieval, the Chinese invention patent with the application number of 200810013482.9 provides structural steel for bridges and a manufacturing method thereof, and the structural steel comprises the following chemical components in percentage by weight: c: 0.04-0.08%, Si: 0.25 to 0.40%, Mn: 1.20 to 1.35%, Cu: 0.30-0.45%, Ni: 0.20 to 0.35%, Cr: 0.30 to 0.55%, Mo: 0.04-0.07%, V: 0.02-0.07%, and the balance of Fe and inevitable impurities. The process flow is characterized in that: the method comprises the steps of adopting converter smelting, RH or VD vacuum furnace and LF treatment, and adopting a two-stage controlled rolling and controlled cooling process, wherein the heating temperature is 1150-1200 ℃, the final rolling temperature is about 850 ℃, the final cooling temperature is 350-550 ℃, and the cooling speed is 5-15 ℃/s. Although the steel grade has corrosion resistance, the corrosion resistance coefficient I value is lower than that of the steel grade; meanwhile, the steel grade adopts a lath bainite and ferrite structure system, so the final cooling temperature is generally lower, the plate type of the steel plate is not good easily during large-scale production, and finally, the unevenness is higher when a user uses the steel plate, so that the construction is difficult.
The invention patent of China with the application number of 201110123433.2 provides bridge structural steel and a production method thereof, wherein the production method comprises molten iron pretreatment, top-bottom combined blown converter smelting, LF refining, RH refining, slab continuous casting, wide and thick plate rolling and normalizing heat treatment, and the produced bridge structural steel comprises the following chemical components in percentage by weight: c: 0.11 to 0.16%, Si: 0.10 to 0.45%, Mn: 1.35-1.70%, S is less than or equal to 0.010%, P is less than or equal to 0.020%, Nb: 0.025 to 0.060%, Ti: 0.008-0.030%, V: 0.025 to 0.080%, Ni: 0.10 to 0.50%, Als: 0.015-0.060% of N not more than 40X 10-6、O≤40×10-6、H≤2×10-6The balance being iron and unavoidable impurities, Als represents acid-soluble aluminum. The yield strength of the steel plate is not lower than 370MPa, the tensile strength is not lower than 510MPa, the yield ratio is not higher than 0.75, the elongation after fracture is not lower than 30%, the longitudinal AKv at minus 40 ℃ is not lower than 240J, and the manufacturing requirements of high-speed multi-track railway bridges can be met. Although the steel grade has good impact toughness, the strength grade is slightly low, and meanwhile, the welding performance is seriously influenced by the excessively high content of C, and in addition, the steel grade does not have corrosion resistance.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a corrosion-resistant bridge structural steel plate with the yield strength of 485MPa and a manufacturing method thereof.
In order to achieve the purpose, the structural steel plate for the corrosion-resistant bridge with the yield strength of 485MPa level, which is designed by the invention, comprises the following chemical components in percentage by weight: c: 0.060 to 0.090%, Si: 0.30 to 0.50%, Mn: 1.10-1.35%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, Nb: 0.025-0.045%, V: 0.040-0.070%, Ni: 0.25 to 0.45%, Cu: 0.25 to 0.40%, Cr: 0.45-0.65%, Mo: 0.020-0.080% of Fe and inevitable impurities in balance; moreover, the requirements of welding crack sensitivity combination Pcm is less than or equal to 0.22, the corrosion resistance coefficient I is more than or equal to 6.7, the carbon equivalent CEV is less than or equal to 0.49, and the Nb/Mn ratio is 0.02-0.04; wherein,
Pcm＝C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B，
I＝26.01Cu+3.88Ni+1.20Cr+1.49Si+17.28P-7.29Cu×Ni-9.10Ni×P-3.39Cu2，
CEV＝C+Mn/6+(Cr+V+Mo)/5+(Ni+Cu)/15。
the Mn element can remarkably delay the transformation of the alloy steel in a high-temperature area, greatly improve the solid solubility of Nb in austenite, promote the uniform distribution of the Nb, and greatly exert the influence of the Nb element on the steel structure and performance. When Nb/Mn >0.04, Nb cannot be sufficiently dissolved, and when Nb/Mn <0.02, the promoting effect of Mn on Nb solid solution cannot be sufficiently exerted, which all have an influence on the properties of the steel; meanwhile, the steel of the invention also effectively improves the welding performance by strictly controlling the Pcm value and the carbon equivalent CEV.
Preferably, the steel plate comprises the following chemical components in percentage by weight: c: 0.075-0.085%, Si: 0.35-0.45%, Mn: 1.25-1.35%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, Nb: 0.030-0.045%, V: 0.050 to 0.060%, Ni: 0.30-0.40%, Cu: 0.32 to 0.40%, Cr: 0.50 to 0.60%, Mo: 0.050 to 0.060% of Fe and the balance of inevitable impurities; moreover, the welding crack sensitivity combination Pcm is less than or equal to 0.22, the corrosion resistance coefficient I is greater than or equal to 6.7, the carbon equivalent CEV is less than or equal to 0.49, and the Nb/Mn ratio is 0.02-0.04.
Preferably, the steel plate comprises the following chemical components in percentage by weight: c: 0.083%, Si: 0.39%, Mn: 1.33 percent, P is less than or equal to 0.020 percent, S is less than or equal to 0.010 percent, Nb: 0.038%, V: 0.055%, Ni: 0.34%, Cu: 0.34%, Cr: 0.59%, Mo: 0.052 percent of Fe and inevitable impurities.
Preferably, the steel plate has a yield strength RelNot less than 485MPa, tensile strength Rm: 585-760 MPa, the elongation A is more than or equal to 17%, and the low-temperature impact performance at the temperature of minus 23 ℃ is more than or equal to 200J.
The production method of the corrosion-resistant bridge structural steel plate with the yield strength of 485MPa comprises the following steps:
1) smelting according to the weight percentage ratio of the chemical components, controlling the alloy content in the molten steel and continuously casting into a blank;
2) heating and preserving heat of the casting blank obtained in the step 1), wherein the heating temperature is controlled to be 1220-1290 ℃, the furnace time is 250-400 min, and the heat preservation is carried out for 40-70 min at the temperature of 1180-1220 ℃;
3) and (3) sectional rolling:
rough rolling: controlling the initial rolling temperature of rough rolling to be 1100-1150 ℃, the reduction rate of rough rolling pass is more than or equal to 20%, and the finishing temperature of rough rolling is more than or equal to 1020 ℃;
finish rolling: controlling the initial rolling temperature of finish rolling to be 830-870 ℃, controlling the accumulated reduction rate of three passes after finish rolling to be more than or equal to 40%, and controlling the finish rolling temperature to be 800-830 ℃;
4) and (3) cooling: cooling after final rolling, wherein the starting cooling temperature is controlled to be 750-820 ℃, and the cooling speed is 3-9 ℃/s;
5) quenching and tempering:
quenching: the quenching temperature is 900-940 ℃, and the heat preservation time is 40-90 min;
high-temperature tempering: the tempering temperature is 590-640 ℃, and the furnace time is 60-120 min.
Preferably, in the step 5), the heat-retaining time during quenching is 25 to 40min after the plate thickness is increased, and the heat-retaining time during tempering is 45 to 60min after the plate thickness is increased. For example, when a steel sheet having a thickness of 16mm is produced, the heat-retaining time during quenching is 41 to 56min, and the heat-retaining time during tempering is 61 to 76 min.
The functions of each element and the main process in the invention are as follows:
in the invention, C improves the strength of steel through clearance replacement solid solution strengthening, is one of indispensable elements for ensuring the strength of the steel, can obviously improve the hardenability of the steel and plays a decisive role in the strength and the hardness of the steel, but the increase of the carbon content reduces the plasticity and the impact toughness of the steel and seriously deteriorates the welding performance. The strength and toughness of steel are comprehensively considered, the welding performance is improved by reducing the carbon equivalent, and the proper amount of C is controlled to be 0.06-0.09%.
In the present invention, the main role of Si in steel is solid solution strengthening and deoxidation, which can improve the strength of steel, but too high Si content significantly deteriorates the toughness and weldability of steel, and therefore, the content of Si is controlled at a low level in the present invention: 0.30 to 0.50 percent.
In the invention, Mn is an element for improving the strength and the hardenability of the steel, the Mn content needs to be more than 1.0 percent in order to obtain the strength required by the invention, but when the Mn content is too high, the plasticity and the impact toughness of the steel are reduced, meanwhile, MnS inclusions are formed due to too high Mn content, the corrosion resistance of the machine body is reduced, and the Mn content is designed to be 1.10-1.35 percent by comprehensively considering the toughness and the corrosion resistance of the steel.
In the invention, S is a harmful element remained in steel, can form MnS inclusion with Mn in the steel, is the origin of local corrosion, and simultaneously, the toughness and the weldability of the steel are reduced due to the over-high S content, and the S content is controlled to be less than 0.010 percent.
In the invention, P is an easily segregated element, the toughness and corrosion resistance of steel are reduced along with the increase of the content of P, the welding performance of steel is also rapidly reduced, and the content of P is less than 0.020%.
In the invention, Cu and Ni are austenite forming elements, thereby promoting the formation and stabilization of austenite and improving the tensile strength of the steel plate; the addition of Cu can improve the corrosion resistance and strength of steel and improve the weldability and machining performance of experimental steel; the addition of Ni improves the low-temperature toughness of the steel at the same time, but the welding performance of the steel plate is deteriorated due to the excessively high Ni content; cu in the steel can obviously play a comprehensive role with the added B, the joint addition of Cu and B can further inhibit ferrite formation before bainite transformation, a martensite structure can be obtained more easily during hardening and tempering, but the hot brittleness phenomenon of the steel can be caused by the over-high Cu content, and the surface quality of the steel plate is deteriorated; the phenomenon can be improved by adding a certain amount of Ni and Cu in a matching way, so that the Ni content is controlled to be 0.25-0.45%, and the Cu content is controlled to be 0.25-0.40%.
The Cr is an element which can effectively improve the strength of the steel plate and simultaneously improve the corrosion resistance of the material under an acidic condition, the composite addition effect of the Cr, the Cu and the Ni is better, the ferrite phase transformation can be obviously shifted to the right, the cold speed interval of the bainite phase transformation is widened, the formation of a medium-temperature transformation structure is promoted, and when the Cr content is too high, the toughness of a base material and a heat affected zone can be obviously reduced, so that the Cr content is controlled to be 0.45-0.65%.
According to the invention, the hardenability of Mo can be obviously improved, so that martensite is favorably formed, meanwhile, the corrosion resistance can be improved by adding Mo, but when the content of Mo is higher than 0.4%, the cold crack sensitivity of the steel plate can be improved, and the welding performance is reduced, so that the content of Mo is controlled to be 0.02-0.08%.
Nb is a strong carbon and nitride forming element, can form fine carbide and nitride to effectively nail and roll austenite grain boundaries, prevent austenite grain from further growing up, thereby refining ferrite grain, improving the strength and toughness of steel, simultaneously charge transfer resistance of Nb is increased along with the prolonging of corrosion time in the corrosion process, the corrosion resistance of Nb-containing steel is generally superior to that of Nb-free steel, and the content of Nb in the invention is selected as follows: 0.025 to 0.045%.
The invention has the following advantages:
firstly, the process design is economic and reasonable, the process is simple, the corrosion resistance coefficient I is more than or equal to 6.7, the corrosion resistance is better, protective paint or corrosion inhibitor does not need to be coated on the surface of the bridge steel when the bridge steel is used, and the manufacturing and maintenance cost is greatly reduced;
secondly, the yield strength R of the steel plate is designed and produced by the process of the inventionelNot less than 485MPa, tensile strength Rm: 585-760 MPa, elongation A of more than or equal to 17%, low-temperature impact performance at-23 ℃ of more than or equal to 200J, and good toughness.
Thirdly, the method improves the welding performance of the steel plate by strictly controlling the carbon equivalent CEV to be less than or equal to 0.49 and the Pcm to be less than or equal to 0.22, does not need preheating or preheating temperature to be less than 50 ℃ after welding, does not need heat treatment after welding, and greatly improves the welding efficiency and the welding quality.
Drawings
FIG. 1 is a metallographic structure diagram of a steel sheet produced in example 1.
FIG. 2 is a metallographic structure diagram of a steel sheet produced in example 2.
FIG. 3 is a metallographic structure diagram of a steel sheet produced in comparative example 1.
FIG. 4 is a metallographic structure diagram of a steel sheet produced in comparative example 3.
FIG. 5 is an electron micrograph of precipitated phases of the steel sheet produced in example 1.
Detailed Description
The invention is described in detail below with reference to the attached drawing figures:
table 1 is a list of values of chemical components of each example and comparative example of the present invention;
table 2 shows the chemical compositions satisfying coefficient lists of each example and comparative example of the present invention;
table 3 is a table of the main process parameters of each example of the present invention and comparative example;
table 4 is a table of the results of mechanical property experiments for each example of the present invention and comparative example.
The embodiments of the invention are produced according to the following steps:
1) smelting according to the weight percentage ratio of the chemical components, controlling the alloy content in the molten steel and continuously casting into a blank;
2) heating and preserving heat of the casting blank obtained in the step 1), wherein the heating temperature is controlled to be 1220-1290 ℃, the furnace time is 250-400 min, and the heat preservation is carried out for 40-70 min at the temperature of 1180-1220 ℃;
3) and (3) sectional rolling:
rough rolling: controlling the initial rolling temperature of rough rolling to be 1100-1150 ℃, the reduction rate of rough rolling pass is more than or equal to 20%, and the finishing temperature of rough rolling is more than or equal to 1020 ℃;
finish rolling: controlling the initial rolling temperature of finish rolling to be 830-870 ℃, controlling the accumulated reduction rate of three passes after finish rolling to be more than or equal to 40%, and controlling the finish rolling temperature to be 800-830 ℃;
4) and (3) cooling: cooling after final rolling, wherein the starting cooling temperature is controlled to be 750-820 ℃, and the cooling speed is 3-9 ℃/s;
5) quenching and tempering:
quenching: the quenching temperature is 900-940 ℃, and the heat preservation time is 40-90 min;
high-temperature tempering: the tempering temperature is 590-640 ℃, and the furnace time is 60-120 min.
Table 1 tabulation of chemical composition values for each example and comparative example of the present invention:
table 2 shows that the chemical components of the examples and comparative examples of the present invention satisfy the coefficient list:
table 3 is a table of the main process parameters for each example of the invention and comparative example:
table 4 shows the mechanical property test results of the examples and comparative examples of the present invention:
as can be seen from the data in tables 2 and 4: the steels refined in the embodiments 1-4 of the invention all satisfy the yield strength RelNot less than 485MPa, tensile strength RmThe alloy has the advantages of 585-760 MPa, elongation A of more than or equal to 17%, low-temperature impact performance at-23 ℃ of more than or equal to 200J, corrosion resistance coefficient I of more than or equal to 6.7, carbon equivalent CEV of less than or equal to 0.49, and welding crack sensitivity coefficient Pcm of less than or equal to 0.22.
It can be seen from fig. 1 that the steel sheet produced in example 1 had a structure mainly including tempered sorbite and ferrite, and a relatively large ferrite content; it can be seen from fig. 2 that the steel sheet produced in example 2 has substantially the same structure as example 2, but the ferrite content is significantly reduced; it can be seen from FIG. 3 that the steel sheet produced in comparative example 1 had a structure mainly of tempered sorbite, and no ferrite was observed; it can be seen from FIG. 4 that the steel sheet produced in comparative example 3 is aggregated and distributed with inclusions; it can be seen from FIG. 5 that the steel sheet produced in example 1 had very many and extremely fine precipitates in the precipitated phase, and precipitated plate-like carbides were observed in the structure.
Comparative example 1, which has a higher carbon content, has a significantly higher CEV, and an increase in the carbon content thereof results in an increase in the strength of the experimental steel and a decrease in the impact resistance, which is not satisfactory. It can also be seen from the structure of the examples that the ferrite content gradually decreases with increasing carbon content, and the presence of ferrite improves the impact toughness of the material. Comparative example 2, which has a low Nb content, cannot sufficiently exert the effect of promoting the solid solution of Mn to Nb, resulting in a low strength of the steel sheet, while comparative example 3, which has a high Nb content, cannot sufficiently dissolve Nb, because the Nb/Mn is too high, and aggregates into inclusions in the steel to drastically deteriorate the impact properties of the steel.
The above examples are merely preferred examples and are not intended to limit the embodiments of the present invention.
Claims (6)
1. The utility model provides a corrosion-resistant bridge of 485MPa grades of yield strength is with structural steel plate which characterized in that: the steel plate comprises the following chemical components in percentage by weight: c: 0.060 to 0.090%, Si: 0.30 to 0.50%, Mn: 1.10-1.35%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, Nb: 0.025-0.045%, V: 0.040-0.070%, Ni: 0.25 to 0.45%, Cu: 0.25 to 0.40%, Cr: 0.45-0.65%, Mo: 0.020-0.080% of Fe and inevitable impurities in balance; moreover, the requirements of welding crack sensitivity combination Pcm is less than or equal to 0.22, the corrosion resistance coefficient I is more than or equal to 6.7, the carbon equivalent CEV is less than or equal to 0.49, and the Nb/Mn ratio is 0.02-0.04; wherein,
Pcm＝C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B，
I＝26.01Cu+3.88Ni+1.20Cr+1.49Si+17.28P-7.29Cu×Ni-9.10Ni×P-3.39Cu2，
CEV＝C+Mn/6+(Cr+V+Mo)/5+(Ni+Cu)/15。
2. the structural steel plate for the corrosion-resistant bridge with the yield strength of 485MPa level as claimed in claim 1, wherein: the steel plate comprises the following chemical components in percentage by weight: c: 0.075-0.085%, Si: 0.35-0.45%, Mn: 1.25-1.35%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, Nb: 0.030-0.045%, V: 0.050 to 0.060%, Ni: 0.30-0.40%, Cu: 0.32 to 0.40%, Cr: 0.50 to 0.60%, Mo: 0.050 to 0.060% of Fe and the balance of inevitable impurities; moreover, the welding crack sensitivity combination Pcm is less than or equal to 0.22, the corrosion resistance coefficient I is greater than or equal to 6.7, the carbon equivalent CEV is less than or equal to 0.49, and the Nb/Mn ratio is 0.02-0.04.
3. The structural steel plate for the corrosion-resistant bridge with the yield strength of 485MPa level as claimed in claim 2, wherein: the steel plate comprises the following chemical components in percentage by weight: c: 0.083%, Si: 0.39%, Mn: 1.33 percent, P is less than or equal to 0.020 percent, S is less than or equal to 0.010 percent, Nb: 0.038%, V: 0.055%, Ni: 0.34%, Cu: 0.34%, Cr: 0.59%, Mo: 0.052 percent of Fe and inevitable impurities.
4. The corrosion-resistant bridge structural steel plate with the yield strength of 485MPa according to any one of claims 1-3, which is characterized in that: the steel plate yield strength RelNot less than 485MPa, tensile strength Rm: 585-760 MPa, the elongation A is more than or equal to 17%, and the low-temperature impact performance at the temperature of minus 23 ℃ is more than or equal to 200J.
5. The production method of the 485 MPa-yield-strength corrosion-resistant bridge structural steel plate disclosed by claim 1 is characterized by comprising the following steps of: the method comprises the following steps:
1) smelting according to the weight percentage ratio of the chemical components, controlling the alloy content in the molten steel and continuously casting into a blank;
2) heating and preserving heat of the casting blank obtained in the step 1), wherein the heating temperature is controlled to be 1220-1290 ℃, the furnace time is 250-400 min, and the heat preservation is carried out for 40-70 min at the temperature of 1180-1220 ℃;
3) and (3) sectional rolling:
rough rolling: controlling the initial rolling temperature of rough rolling to be 1100-1150 ℃, the reduction rate of rough rolling pass is more than or equal to 20%, and the finishing temperature of rough rolling is more than or equal to 1020 ℃;
finish rolling: controlling the initial rolling temperature of finish rolling to be 830-870 ℃, controlling the accumulated reduction rate of three passes after finish rolling to be more than or equal to 40%, and controlling the finish rolling temperature to be 800-830 ℃;
4) and (3) cooling: cooling after final rolling, wherein the starting cooling temperature is controlled to be 750-820 ℃, and the cooling speed is 3-9 ℃/s;
5) quenching and tempering:
quenching: the quenching temperature is 900-940 ℃, and the heat preservation time is 40-90 min;
high-temperature tempering: the tempering temperature is 590-640 ℃, and the furnace time is 60-120 min.
6. The production method of the 485 MPa-yield-strength corrosion-resistant bridge structural steel plate according to claim 5, characterized by comprising the following steps: in the step 5), the heat preservation time during quenching is the sum of the plate thickness and the plate thickness for 20-40 min, and the heat preservation time during tempering is the sum of the plate thickness and the plate thickness for 40-60 min.
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