CN111088462A - Production method of hot-rolled steel strip for 610 MPa-grade automobile frame - Google Patents

Production method of hot-rolled steel strip for 610 MPa-grade automobile frame Download PDF

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CN111088462A
CN111088462A CN202010010510.2A CN202010010510A CN111088462A CN 111088462 A CN111088462 A CN 111088462A CN 202010010510 A CN202010010510 A CN 202010010510A CN 111088462 A CN111088462 A CN 111088462A
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steel strip
production method
mpa
rolled steel
hot
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CN111088462B (en
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袁勤攀
樊雷
杨跃标
张金旺
李宗强
赵忠云
叶姜
刘崇林
梁武三
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Liuzhou Iron and Steel Co Ltd
Guangxi Liuzhou Iron and Steel Group Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226Hot rolling
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/14Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/005Ferrite
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/009Pearlite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The embodiment of the invention provides a production method of a hot rolled steel strip for a 610 MPa-level automobile beam, which comprises the following steps: converter smelting, LF furnace refining, continuous casting, rolling planning, plate blank heating, rough rolling, high-pressure water descaling, finish rolling, laminar cooling, coiling and heap cooling; the hot-rolled steel strip for the 610 MPa-grade automobile beam comprises the following chemical components in percentage by weight: 0.060 to 0.090%, 0.10 to 0.20% of Si, Mn: 1.35-1.50%, phosphorus P is less than or equal to 0.020%, sulfur S is less than or equal to 0.008%, and aluminum Als: 0.015 to 0.050%, niobium Nb: 0.035-0.045%, titanium Ti: 0.035-0.045%, nitrogen N is less than or equal to 0.0045%, and the balance is Fe and inevitable impurities.

Description

Production method of hot-rolled steel strip for 610 MPa-grade automobile frame
Technical Field
The invention belongs to the technical field of steel production, and particularly relates to a production method of a hot-rolled steel strip for a 610 MPa-grade automobile beam.
Background
Commercial vehicle frames are generally formed by riveting cross beams, longitudinal beams, lining beams and part of reinforcements, and the quality of the frames affects the service life and the driving safety of the whole vehicle, so that the steel strip for the automobile frame has to have good comprehensive properties such as formability, weldability, fatigue resistance, low-temperature toughness and the like. With the development of commercial vehicles towards light weight, the strength grade of the steel belt for the automobile girder is gradually changed from the conventional 510MPa grade to the 610MPa grade, even 700MPa grade, but with the improvement of the strength of the steel belt for the girder, the problem of camber (side bending) of the steel belt for the girder after shearing is increasingly prominent, and the riveting of the girder is seriously affected, so that the automobile girder plate has the comprehensive performance, and also needs higher strength and good plate shape.
With the rapid development of the steel industry in China, more steel mills in China develop steel belts for 600-610 MPa-level high-strength automobile girders with different characteristics through different process routes, and steel climbing 'hot rolled steel plates for 610 MPa-level automobile girders and production methods thereof' (application number: 201711181862.9), wherein the steel belts comprise the following chemical components: 0.05-0.10%, Si: less than or equal to 0.15 percent, Mn: 1.30-1.60%, P: less than or equal to 0.020%, S: less than or equal to 0.010 percent, Nb: 0.010-0.040%, the balance being Fe and Fe, and heating the billet at 1210-1240 ℃ for more than 150 min; the inlet temperature of finish rolling is 950-1020 ℃, and the finish rolling temperature is 830-870 ℃; the coiling temperature is 590-640 ℃; the cooling is carried out at a speed of 20-70 ℃/s until the temperature is 590-640 ℃. And after coiling and heat preservation for 10-26 h, feeding into a slow cooling pit stack for slow cooling for 65-96 h to obtain a finished product. The process adopts a single Nb microalloying process, inevitably needs low-temperature rolling and low-temperature coiling, has large internal stress of steel although the strength of the steel reaches 610MPa, and needs to independently set a slow cooling pit in a storehouse for slow cooling for a long time.
An automobile beam steel with stable strength performance and Rm more than or equal to 600MPa and a production method (CN 110331344A) comprises the following components in percentage by weight: by adopting a Nb-Ti composite addition control technology and a low-temperature rolling technology, the automobile girder steel with Rm more than or equal to 600MPa is developed, and the automobile girder steel comprises the following components: 0.06-0.08%, Mn: 1.4-1.6%, P: 0-0.02%, S is less than or equal to 0.004%, Al: 0.020 to 0.060%, Nb: 0.033 to 0.048%, Ti: 0.02-0.03%, N is less than or equal to 0.004%; the final rolling and coiling temperature is controlled to be 830-870 ℃ and 530-610 ℃ according to the thickness, and the low-temperature rolling and the low-temperature coiling have high requirements on a rolling mill and a coiling machine and can cause the problems of poor plate shape, large internal stress and the like.
The 610 MPa-grade automobile beam steel and the manufacturing method thereof (CN 104988398B) steel comprise the following chemical components: carbon: 0.07 percent to 0.09 percent; silicon < 0.10%; manganese: 1.50% -1.65%; phosphorus is less than or equal to 0.015 percent; sulfur is less than or equal to 0.010 percent; solid solution of aluminum: 0.020% -0.070%; niobium: 0.045-0.065%; titanium: 0.003 to 0.01 percent; nitrogen is less than or equal to 0.004 percent. The heating temperature in the hot continuous rolling process is 1200-1300 ℃, the outlet temperature of rough rolling is 1040-1140 ℃, and the finishing temperature is 800-860 ℃; the coiling temperature in the coiling process is 550-590 ℃, the actually listed chemical components are mainly independently niobium microalloyed, and low-temperature rolling and rapid cooling after rolling are inevitably needed, and low-temperature coiling is carried out.
A high-toughness 600 MPa-level automobile girder steel and a production method thereof (CN 108315639A), the high-toughness 600 MPa-level automobile girder steel is characterized in that: the chemical components and weight percentage content are as follows: c: 0.035 to 0.055%, 0.10 to 0.20% of Si, Mn: 1.50-1.70%, P is less than or equal to 0.015%, S is less than or equal to 0.006%, Als: 0.015 to 0.060%, 0.050 to 0.070% of Nb, Ti: 0.030-0.045%, and N is less than or equal to 0.0050%, the fine-grain high-toughness automobile girder plate is obtained through a controlled rolling and cooling process, too low carbon is beneficial to impact toughness, but easily causes impact resilience caused by high yield ratio of steel, and in addition, more Nb is added in the process, so that the cost is relatively high.
The steel strip for the 600L automobile beam with good forming performance and the production method (CN 110184535A) are characterized in that the steel strip for the 600L automobile beam with good forming performance comprises the following chemical components in percentage by mass: c: 0.03-0.09%, Si is less than or equal to 0.15%, Mn: 1.2-1.5%, P is less than or equal to 0.016%, S is less than or equal to 0.006%, Als: 0.015 to 0.050%, Nb: 0.005-0.025%, Ti: 0.055-0.085%, and the balance Fe and inevitable impurities. The gas N, H and O in the casting blank sampling inspection steel are less than or equal to 45ppm, less than or equal to 1.5ppm and less than or equal to 15 ppm. The process mainly adopts low-carbon niobium-titanium composite microalloying, but the niobium is added less, the titanium microalloying is actually mainly adopted, the control requirement on gas elements such as N, 0 and the like is higher, the impact toughness and the mechanical property stability of the single titanium microalloyed steel are poorer, and the production process window is narrower.
In summary, there is an urgent need for a new production method of 610MPa grade hot rolled steel strip for automobile frame, which has lower requirement for equipment, no need of new cooling pit, increased investment, moderate product cost, and obvious advantages of the produced finished product and the shape of the steel plate sheared by the user, and can realize continuous and mass production.
In the process of implementing the invention, the applicant finds that at least the following problems exist in the prior art: the production process in the existing production method of the hot rolled steel strip for the 610 MPa-grade automobile frame has high requirements on equipment, a newly-built slow cooling pit is required, the investment is increased, the product cost is high, and the hot rolled steel strip for the 610 MPa-grade automobile frame is easy to have poor plate shape and large internal stress.
Disclosure of Invention
The embodiment of the invention provides a production method of a 610 MPa-grade hot rolled steel strip for automotive girders, which can solve the problems that the production process in the existing production method of the 610 MPa-grade hot rolled steel strip for the automotive girders has high requirements on equipment, a newly-built cooling buffer pit is needed, the investment is increased, the product cost is high, the 610 MPa-grade hot rolled steel strip for the automotive girders is easy to have poor plate shape and large internal stress, and the like.
In order to achieve the above object, in one aspect, an embodiment of the present invention provides a method for producing a hot rolled steel strip for a 610MPa automotive frame, where the production process of the hot rolled steel strip for the 610MPa automotive frame includes: converter smelting, LF furnace refining, continuous casting, rolling planning, plate blank heating, rough rolling, high-pressure water descaling, finish rolling, laminar cooling, coiling and heap cooling; the hot-rolled steel strip for the 610 MPa-grade automobile beam comprises the following chemical components in percentage by weight: 0.060 to 0.090%, 0.10 to 0.20% of Si, Mn: 1.35-1.50%, phosphorus P is less than or equal to 0.020%, sulfur S is less than or equal to 0.008%, and aluminum Als: 0.015 to 0.050%, niobium Nb: 0.035-0.045%, titanium Ti: 0.035-0.045%, nitrogen N is less than or equal to 0.0045%, and the balance is Fe and inevitable impurities.
Further, the rolling planning refers to batch production of the DC01 or SPCC cold-rolled base plates coiled at 620 ℃ before 3 hours before rolling the girder plate, transition steel coils are Q235B, Q355B and high-strength steel in sequence, the transition steel coils are more than 12 coils, and the high-strength steel with the strength of 610MPa grade is more than 3 coils.
Further, the slab heating means that the slab is heated in a four-section stepping heating furnace at the furnace gas temperature of 1160-1260 ℃ for more than 160min, the furnace gas temperature of the three heating sections is 1220-1260 ℃, the heating time is 25-35 min, the furnace gas temperature of the soaking section is 1220-1250 ℃, and the heat preservation time is 35-45 min.
Further, the rough rolling refers to performing 5-7 times of rough rolling after the plate blank is taken out of the heating furnace, and reducing the thickness of the plate blank from 220mm to 35-50 mm.
Further, the high-pressure water descaling is to ensure that the descaling water is above 22MPa before finish rolling, the descaling water is between F2 and F3 between finish rolling mills, and the cooling water of the machine frame is completely closed.
Further, the finish rolling means that the temperature of the rough-rolled intermediate blank entering the finish rolling is 980-1050 ℃, the intermediate blank is continuously rolled by 6-7 finish rolling mills, and the finish rolling temperature of the finish rolling end frame is 860-920 ℃;
further, the laminar cooling means that the steel strip enters a laminar cooling system with the length of 90m for cooling after passing through the last rolling mill, the steel strip is cooled to 600-660 ℃ at the speed of 20-50 ℃/s, and the cooling mode is a forward 2/4 cooling mode.
Further, the coiling and the stack cooling are carried out by stacking the coiled 610MPa automobile girder steel hot rolled steel strip in a warehouse, rolling the DC01 or SPCC cold rolled substrate within 3 hours around the 610MPa automobile girder steel hot rolled steel strip, and the stack cooling time is more than 48 hours.
The technical scheme has the following beneficial effects: the invention provides a production method of a hot-rolled steel strip for a 610 MPa-grade automobile crossbeam by adopting a low-carbon niobium-titanium composite component system and matching with a corresponding controlled cooling process; the hot rolled steel strip produced by the production method has higher rolling temperature and coiling temperature coils, the loads of a rolling mill and a coiling machine are small, and the dimensional precision and the shape of the steel coil are well controlled; descaling and cooling between frames are reduced in the finish rolling process, the cooling speed after rolling is moderate, uneven stress caused in the steel strip rolling and cooling processes is reduced, slow cooling stress is released, and camber of the steel strip after longitudinal cutting is controlled within 2mm/10 m.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of the cold stacking of a hot rolled steel strip for a 610MPa automotive frame according to the present invention
FIG. 2 is a metallographic structure diagram of a hot-rolled steel strip for a 610MPa automotive frame according to the present invention, which is enlarged by 100 times
The reference numerals are represented as: 1. DC01 or SPCC cold rolled substrate; 2. a 610MPa grade hot rolled steel strip for an automobile beam; 3. ferrite; 4. pearlite.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a production method of a hot rolled steel strip for a 610 MPa-level automobile beam, which comprises the following steps: converter smelting, LF furnace refining, continuous casting, rolling planning, plate blank heating, rough rolling, high-pressure water descaling, finish rolling, laminar cooling, coiling and heap cooling; the hot-rolled steel strip for the 610 MPa-grade automobile beam adopts a low-carbon niobium-titanium composite component system, and comprises the following chemical components in percentage by weight: 0.060 to 0.090%, 0.10 to 0.20% of Si, Mn: 1.35-1.50%, phosphorus P is less than or equal to 0.020%, sulfur S is less than or equal to 0.008%, and aluminum Als: 0.015 to 0.050%, niobium Nb: 0.035-0.045%, titanium Ti: 0.035-0.045%, nitrogen N is less than or equal to 0.0045%, and the balance is Fe and inevitable impurities.
In the production method of the hot rolled steel strip for the 610 MPa-grade automobile beam, the chemical components of a plate blank obtained by continuously casting the steel strip are carbon C: 0.060 to 0.090%, 0.10 to 0.20% of Si, Mn: 1.35-1.50%, phosphorus P is less than or equal to 0.020%, sulfur S is less than or equal to 0.008%, and aluminum Als: 0.015 to 0.050%, niobium Nb: 0.035-0.045%, titanium Ti: 0.035-0.045%, nitrogen N is less than or equal to 0.0045%, and the balance is Fe and inevitable impurities.
As shown in Table 1, the invention provides 4 examples of the chemical compositions of hot rolled steel strips produced by the production method of 610 MPa-grade automobile hot rolled steel strips, wherein the chemical composition and weight percentage of the hot rolled steel strips for 610 MPa-grade automobile beams are carbon C: 0.06%, silicon Si: 0.15%, manganese Mn: 1.43%, phosphorus P: 0.018%, sulfur S: 0.005%, aluminum Als: 0.035%, niobium Nb: 0.038%, titanium Ti: 0.043%, nitrogen N: 0.0034%.
The hot-rolled steel strip for the 610 MPa-grade automobile beam comprises the following chemical components in percentage by weight: 0.07%, silicon Si: 0.15%, manganese Mn: 1.46%, phosphorus P: 0.019%, sulfur S: 0.006%, aluminum Als: 0.030%, niobium Nb: 0.039%, titanium Ti: 0.040%, nitrogen N: 0.0038%.
The hot-rolled steel strip for the 610 MPa-grade automobile beam comprises the following chemical components in percentage by weight: 0.08%, silicon Si: 0.15%, manganese Mn: 1.45%, phosphorus P: 0.018%, sulfur S: 0.005%, aluminum Als: 0.033%, niobium Nb: 0.041%, titanium Ti: 0.041%, nitrogen N: 0.0036%.
The hot-rolled steel strip for the 610 MPa-grade automobile beam comprises the following chemical components in percentage by weight: 0.08%, silicon Si: 0.15%, manganese Mn: 1.48%, phosphorus P: 0.019%, sulfur S: 0.006%, aluminum Als: 0.031%, niobium Nb: 0.042%, titanium Ti: 0.042%, nitrogen N: 0.0039%.
Further, the rolling planning refers to batch production of the DC01 or SPCC cold-rolled base plate coiled at 620 ℃ before 3 hours before rolling the girder plate, transition steel coils are Q235B, Q355B and high-strength steel in sequence, the transition steel coils are more than 12 coils, and the high-strength steel with the strength of 610MPa grade is more than 3 coils; the stress releasing effect of high-temperature stack cooling is realized by mainly preventing the cold-rolled substrate with high temperature enough in advance for 3 hours, the transition from the DC01/SPCC cold-rolled substrate with low strength to the Q235B, Q355B and high-strength steel is from mild steel to medium strength and then to high strength, so that the gradual adaptive transition of rolling equipment (such as roll thermal convexity), a control model and the like can be realized, the transition material with each strength is more than 3 rolls, and finally good control of the plate shape of the first three rolls of 610MPa is realized.
Further, the slab heating means that the slab is heated in a four-section stepping heating furnace at the furnace gas temperature of 1160-1260 ℃ for more than 160min, the furnace gas temperature of the three heating sections is 1220-1260 ℃, the heating time is 25-35 min, the furnace gas temperature of the soaking section is 1220-1250 ℃, and the heat preservation time is 35-45 min.
Further, the rough rolling refers to performing 5-7 times of rough rolling after the plate blank is taken out of the heating furnace, and reducing the thickness of the plate blank from 220mm to 35-50 mm.
Further, the high-pressure water descaling is to ensure that the descaling water is above 22MPa before finish rolling, the descaling water is arranged between an F2 finish rolling mill and an F3 finish rolling mill, and the cooling water of the rack is completely closed.
In the embodiment with the thickness specification of 5mm, 8mm and 10mm shown in table 2, the finish rolling refers to that the temperature of the intermediate blank after rough rolling is 980-1050 ℃ and the intermediate blank is continuously rolled by 6-7 finish rolling mills, and the final rolling temperature of the final stand of the finish rolling is 860-920 ℃; the rolling temperature is higher, and the load of the rolling mill is small.
Further, the laminar cooling means that the steel strip enters a laminar cooling system with the length of 90m for cooling after passing through the last rolling mill, the steel strip is cooled to 600-660 ℃ at the speed of 20-50 ℃/s, and the cooling mode is a forward 2/4 cooling mode; the cooling speed after rolling is moderate, the stress unevenness caused by the steel strip rolling and cooling process is reduced, the slow cooling stress is released, and the camber of the steel strip after longitudinal cutting is controlled within 2mm/10 m.
Further, the coiling and the stack cooling are to stack the hot rolled steel strip for the 610MPa automobile girder steel after coiling in a warehouse, roll the DC01 cold rolled substrate within 3 hours around the hot rolled steel strip for the 610MPa automobile girder steel, and the stack cooling time is more than 48 hours; the heap cooling method has low requirements on equipment, does not need to newly build a slow cooling pit and increases investment.
The invention adopts a low-carbon niobium-titanium composite component system and is matched with a corresponding controlled cooling process to successfully develop a 610 MPa-grade hot-rolled steel strip for an automobile beam; the rolling temperature and the coiling temperature are high in the rolling process, the loads of a rolling mill and a coiling machine are small, and the size precision and the shape of a steel coil are well controlled; descaling and cooling between frames are reduced in the finish rolling process, the cooling speed after rolling is moderate, uneven stress caused in the steel strip rolling and cooling processes is reduced, slow cooling stress is released, and camber of the steel strip after longitudinal cutting is controlled within 2mm/10 m.
Table 1 examples of chemical compositions
Figure BDA0002356975840000061
TABLE 2 Rolling example
Figure BDA0002356975840000062
In the laminar cooling mode, the forward direction refers to 2/4 mode, the forward direction refers to the rolling direction at the outlet of the finishing mill, and the 2/4 mode refers to 2 rows of 4 rows of cooling water pipes, namely half of the cooling water pipes.
TABLE 3 examples of mechanical properties
Figure BDA0002356975840000071
As shown in Table 3, the yield strength ReL of the embodiment of the production method of the hot rolled steel strip for the 610 MPa-grade automobile beam is more than or equal to 500 MPa; the tensile strength Rm is more than or equal to 610 MPa; the elongation A is more than or equal to 18 percent; wide cold bending (b is 35mm) and good performance (d is 0mm), 20 ℃ impact energy is more than or equal to 34J, and camber after longitudinal cutting is controlled within 2mm/10 m. Meets the specific performance requirements of a hot-rolled steel strip for a 610 MPa-grade automobile beam.
It should be understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy presented.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (8)

1. A production method of a hot rolled steel strip for a 610 MPa-grade automobile beam is characterized by comprising the following steps of:
the production method of the hot rolled steel strip for the 610 MPa-grade automobile frame comprises the following steps: converter smelting, LF furnace refining, continuous casting, rolling planning, plate blank heating, rough rolling, high-pressure water descaling, finish rolling, laminar cooling, coiling and heap cooling; the hot-rolled steel strip for the 610 MPa-grade automobile beam comprises the following chemical components in percentage by weight: 0.060 to 0.090%, 0.10 to 0.20% of Si, Mn: 1.35-1.50%, phosphorus P is less than or equal to 0.020%, sulfur S is less than or equal to 0.008%, Als: 0.015 to 0.050%, niobium Nb: 0.035-0.045%, titanium Ti: 0.035-0.045%, nitrogen N is less than or equal to 0.0045%, and the balance is Fe and inevitable impurities.
2. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
the rolling planning refers to batch production of DC01 or SPCC cold-rolled base plates coiled at 620 ℃ before 3 hours before rolling the girder plate, transition steel coils are Q235B, Q355B and high-strength steel in sequence, the transition steel coils are more than 12 coils, and the high-strength steel with the strength of 610MPa grade is more than 3 coils.
3. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
the slab heating means that the slab is heated in a four-section stepping heating furnace at the furnace gas temperature of 1160-1260 ℃ for more than 160min, the furnace gas temperature of the three heating sections is 1220-1260 ℃, the heating time is 25-35 min, the furnace gas temperature of the soaking section is 1220-1250 ℃, and the heat preservation time is 35-45 min.
4. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
and the rough rolling refers to performing 5-7 times of rough rolling after the plate blank is taken out of the heating furnace, and compressing the plate blank from 220mm to 35-50 mm in thickness.
5. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
the high-pressure water descaling is that before finish rolling, the descaling water is ensured to be above 22MPa, the descaling water between an F2 finish rolling mill and an F3 finish rolling mill is arranged between the finish rolling mills, and the cooling water of the stand is completely closed.
6. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
the finish rolling refers to that the temperature of the rough-rolled intermediate blank entering the finish rolling is 980-1050 ℃, the intermediate blank is continuously rolled by 6-7 finish rolling mills, and the finish rolling temperature of the finish rolling end frame is 860-920 ℃.
7. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
and the laminar cooling means that the steel strip enters a laminar cooling system with the length of 90m to be cooled after passing through the last rolling mill, the steel strip is cooled to 600-660 ℃ at the speed of 20-50 ℃/s, and the cooling mode is a forward 2/4 cooling mode.
8. The production method of the 610 MPa-grade hot-rolled steel strip for the automobile frame as claimed in claim 1, wherein the production method comprises the following steps:
and the coiling and the stack cooling are that the coiled 610MPa hot rolled steel strip for the automobile girder steel is stacked in a warehouse, a DC01 or SPCC cold rolled substrate is rolled around the 610MPa hot rolled steel strip for the automobile girder steel within 3 hours, and the stack cooling time is more than 48 hours.
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