CN105937011B - Low yield strength cold rolling high strength steel plate and preparation method thereof - Google Patents
Low yield strength cold rolling high strength steel plate and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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Abstract
The present invention relates to low yield strength cold rolling high strength steel plate and preparation method thereof, belongs to automobile cold-rolled high-strength steel technical field.The present invention provides low yield strength cold rolling high strength steel plate, which is mainly made of ferrite and bainite, its yield strength is 230~260MPa, and tensile strength is 400~440MPa, and elongation is 40.0~43.0%, and the preparation method of the steel plate is as follows：Smelt steel bar plate；Fluid origin slab is obtained into hot rolled coil after heating, de-scaling, roughing, finish rolling and section cooling；By hot rolled coil pickling, cold-rolled thin steel strip is then cold rolled to；By cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made.Good combination property of the present invention, relatively low with excellent formability energy, yield strength and yield tensile ratio, elongation is higher；C, the constituent content such as Si, Mn is less, has superior weldability energy；Its preparation method is simple, and production cost is low, easily promotes.
Description
Technical field
The present invention relates to low yield strength cold rolling high strength steel plate and preparation method thereof, belongs to automobile cold-rolled high-strength steel skill
Art field.
Background technology
With the development of automotive light weight technology technology, automobile steel develops towards high-strength steel direction becomes inexorable trend.It is double
The high-strength steel such as phase steel have the characteristics that low yield strength, high-tensile and excellent plasticity, become automobile using first choice high-strength steel, its
Dosage is estimated will be more than 70% in the advanced high-strength steel of automobile using.With the continuous release of internal vapor sweep production capacity, high-strength steel city
The competition of field is also more and more fierce, and the high-strength steel of low-cost and high-performance has become the target that each enterprise is pursued, and is greatly closed
Note.
Patent CN 104195434A disclose 390MPa grades of car inner structural member hot-dip galvanized high-strength steels of tensile strength and
Its production method, its chemical composition mass percent are：C：0.0027~0.0035%, Si：0.071~0.095%, Mn：
0.78~0.95%, P：0.060~0.075%, S≤0.003%, Als：0.015~0.030%, Nb：0.040~
0.045%, Ti：0.039~0.045%, B：0.0008~0.0014%, N≤0.003%, surplus are Fe and inevitable miscellaneous
Matter；By 935~955 DEG C of finish to gauges, 680~700 DEG C batch, 790~810 DEG C of annealing have obtained tensile strength more than 390MPa
Hot-dip galvanized high-strength steel.Although the cold-rolled high-strength prepared by its chemical composition and production method have excellent mechanical property and
Forming property, but the high-strength steel be ultra-low-carbon steel, it is necessary to carry out the processes such as RH application of vacuum, its production difficulty and manufacture cost compared with
It is high.
Patent CN 103882292A disclose a kind of carbon structural steels production method, its chemical composition percentage is：C：
0.06~0.10%, Si≤0.60%, Mn：1.20~1.50%, Al：0.02~0.06%, P≤0.030%, S≤
0.010%, N：0.0020~0.0050%, surplus is Fe and inevitable impurity；Pass through 860~900 DEG C of finish to gauges, 600~640
DEG C batch, 760~800 DEG C of annealing, 650~680 DEG C of slow cooling, 360~400 DEG C of Wetted constructures have obtained tensile strength and have been more than
The cold rolling carbon structural steels of 400MPa.The cold rolling carbon structural steels produced by this method meet mechanical property requirements, but C, Mn
Content is higher to influence its welding performance, while needs accurate control N content to make STEELMAKING PRODUCTION difficulty and cost increase.
The content of the invention
First technical problem to be solved by this invention is to provide a kind of more preferable low yield strength cold rolling of welding performance
High-strength steel sheet.
The chemical composition of the low yield strength cold rolling high strength steel plate is by mass percentage：C：0.03~0.05%,
Si≤0.10%, Mn：1.0~1.30%, Als：0.02~0.06%, P≤0.020%, S≤0.015%, N≤0.006%,
Surplus is Fe and inevitable impurity.
Further, the low yield strength cold rolling high strength steel plate, chemical composition mass percent are preferred：C：0.03~
0.05%, Si≤0.05%, Mn：1.00~1.15%, Als：0.03~0.05%, P≤0.015%, S≤0.010%, N≤
0.005%, surplus is Fe and inevitable impurity.
Carbon：C determines the intensity, plasticity and forming property of steel plate as one of most important component of high intensity.C is steel
The most obvious element of solid solution strengthening effect in iron material, C content increase by 0.1% is dissolved in steel, its intensity can improve about 450MPa.
When C content is too low, the stability and martensite hardenability of austenite decline, and cause low strength, are generally not less than in high intensity
0.02%；When C content is excessive, the plasticity and welding performance of high intensity decline, and 0.20% is generally not more than in high intensity.The present invention
C content is 0.03~0.06%, is preferably 0.03~0.05%, can meet requirement of the steel plate to intensity, plasticity and forming property.
Silicon：Si can be solid-solution in the intensity that steel is improved in ferrite and austenite, its effect is only second to C, P, compared with Mn, Cr, Ti
It is strong with the element such as Ni；Si can also suppress the precipitation of carbide in ferrite, solid solution C atoms is fully enriched with into austenite,
So as to improve its stability.However, during Si too high levels, the scale on surface that Si is formed in heating furnace is very difficult to remove, and increases
De-scaling difficulty is added.Si content≤0.10% of the present invention, is preferably≤0.05%, yield strength can be met the requirements.
Manganese：Mn is common solution strengthening element in good deoxidier and desulfurizing agent, and steel, in high intensity it is general not
Less than 1.20%.Mn can both combine to form a variety of carbide with C and play the role of precipitation strength, and also dissolving in matrix strengthens admittedly
Molten reinforcing effect.Mn easily combines to form high melting compound MnS with S, so as to eliminate or weaken hot-short existing caused by FeS
As improving the hot-working character of steel.Mn can improve stabilization of austenite, move to right C curve, so as to significantly reduce martensite
Critical cooling rate.Mn contents of the present invention are 0.90~1.30%, are preferably 1.00~1.20%, can obtain certain volume fraction
Bainite structure.
Aluminium：Al is deoxidier common in steel, while can form AlN pinning crystal boundaries, so as to play the work of crystal grain thinning
With；In addition, Al is similar to Si effects, Carbide Precipitation can be suppressed, so that the fully rich carbon of austenite.Al content of the present invention is
0.02~0.06%, it is preferably 0.03~0.05%, meets the needs of steel is to deoxidier.
Further, the low yield strength cold rolling high strength steel plate, is mainly made of ferrite and bainite, it is surrendered
Intensity is 230~260MPa, and tensile strength is 400~440MPa, and elongation is 40.0~43.0%.
Further, the low yield strength cold rolling high strength steel plate, is made with the following method：
(1) smelting procedure：A, according to chemical composition mass percent smelting steel；B, the steel that a steps are smelted is cast as slab；
(2) hot-rolled process：Fluid origin slab is obtained into hot rolling after heating, de-scaling, roughing, finish rolling and section cooling
Volume, wherein finish rolling start rolling temperature are 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 645~700 DEG C；
(3) acid rolls process：By above-mentioned hot rolled coil pickling, cold-rolled thin steel strip is then cold rolled to, wherein cold rolling reduction ratio is 60
~74%；
(4) continuous annealing process：By above-mentioned cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made；
Wherein annealing temperature is 780~820 DEG C, and 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature,
Its slow cooling speed is that CR1 is 1~8 DEG C/s, is quickly cooled to 250~350 DEG C of overaging temperature immediately, its rapid cooling speed CR2 is
10~50 DEG C/s, it is finally cooled to room temperature；
Wherein slow cooling speed CR1 preferably 5~8 DEG C/s, rapid cooling speed CR2 preferably 25~35 DEG C/s.
Further, the coiling temperature is 645~670.
Further, the cold rolling reduction ratio is 61~69%.
The invention solves Second Problem to be to provide the more preferable low yield strength cold rolling of the above-mentioned welding performance of manufacture high
The method of strength steel sheet, this method comprises the following steps：
(1) smelting procedure：A, according to chemical composition mass percent smelting steel；B, the steel that a steps are smelted is cast as slab；
(2) hot-rolled process：Fluid origin slab is obtained into hot rolling after heating, de-scaling, roughing, finish rolling and section cooling
Volume, wherein finish rolling start rolling temperature are 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 645~700 DEG C；
(3) acid rolls process：By above-mentioned hot rolled coil pickling, cold-rolled thin steel strip is then cold rolled to, wherein cold rolling reduction ratio is 60
~74%；
(4) continuous annealing process：By above-mentioned cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made；
Wherein annealing temperature is 780~820 DEG C, and 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature,
Its slow cooling speed is that CR1 is 1~5 DEG C/s, is quickly cooled to 250~350 DEG C of overaging temperature immediately, its rapid cooling speed CR2 is
10~50 DEG C/s, it is finally cooled to room temperature.
Further, coiling temperature is 645~670 in the preparation method of low yield strength cold rolling high strength steel plate.
Further, cold rolling reduction ratio is 61~69% in the preparation method of low yield strength cold rolling high strength steel plate.
For the present invention is compared to traditional cold rolling high-strength steel, it is comprehensive to improve its that reduction C content adds Mn contents at the same time
Can, have the advantages that：
(1) excellent formability energy, yield strength and yield tensile ratio are relatively low, and elongation is higher；
(2) constituent content such as C, Si, Mn is less, has superior weldability energy；
(3) its preparation method is simple, and production cost is low, easily promotes.
Brief description of the drawings
Fig. 1 is the continuous annealing process schematic diagram of low yield strength cold rolling high strength steel plate of the present invention；
Fig. 2 is the microstructure morphology of low yield strength cold rolling high strength steel plate of the present invention.
Reference numeral：CR1- slow cooling speed, CR2- rapid cooling speed, I-heating, the insulation of II-two-phase section, III-slow cooling, IV-it is fast
Cold, V-overaging, VI-end are cold.
Embodiment
The present invention provides a kind of more preferable low yield strength cold rolling high strength steel plate of welding performance, the low yield strength are cold
The chemical composition for rolling high-strength steel sheet is by mass percentage：C：0.03~0.05%, Si≤0.10%, Mn：1.0~
1.30%, Als：0.02~0.06%, P≤0.020%, S≤0.015%, N≤0.006%, surplus are Fe and inevitable miscellaneous
Matter.
Further, the low yield strength cold rolling high strength steel plate, chemical composition mass percent are preferred：C：0.03~
0.05%, Si≤0.05%, Mn：1.00~1.15%, Als：0.03~0.05%, P≤0.015%, S≤0.010%, N≤
0.005%, surplus is Fe and inevitable impurity.
Carbon：C determines the intensity, plasticity and forming property of steel plate as one of most important component of high intensity.C is steel
The most obvious element of solid solution strengthening effect in iron material, C content increase by 0.1% is dissolved in steel, its intensity can improve about 450MPa.
When C content is too low, the stability and martensite hardenability of austenite decline, and cause low strength, are generally not less than in high intensity
0.02%；When C content is excessive, the plasticity and welding performance of high intensity decline, and 0.20% is generally not more than in high intensity.The present invention
C content is 0.03~0.06%, is preferably 0.03~0.05%, can meet requirement of the steel plate to intensity, plasticity and forming property.
Silicon：Si can be solid-solution in the intensity that steel is improved in ferrite and austenite, its effect is only second to C, P, compared with Mn, Cr, Ti
It is strong with the element such as Ni；Si can also suppress the precipitation of carbide in ferrite, solid solution C atoms is fully enriched with into austenite,
So as to improve its stability.However, during Si too high levels, the scale on surface that Si is formed in heating furnace is very difficult to remove, and increases
De-scaling difficulty is added.Si content≤0.10% of the present invention, is preferably≤0.05%, yield strength can be met the requirements.
Manganese：Mn is common solution strengthening element in good deoxidier and desulfurizing agent, and steel, in high intensity it is general not
Less than 1.20%.Mn can both combine to form a variety of carbide with C and play the role of precipitation strength, and also dissolving in matrix strengthens admittedly
Molten reinforcing effect.Mn easily combines to form high melting compound MnS with S, so as to eliminate or weaken hot-short existing caused by FeS
As improving the hot-working character of steel.Mn can improve stabilization of austenite, move to right C curve, so as to significantly reduce martensite
Critical cooling rate.Mn contents of the present invention are 0.90~1.30%, are preferably 1.00~1.20%, can obtain certain volume fraction
Bainite structure.
Aluminium：Al is deoxidier common in steel, while can form AlN pinning crystal boundaries, so as to play the work of crystal grain thinning
With；In addition, Al is similar to Si effects, Carbide Precipitation can be suppressed, so that the fully rich carbon of austenite.Al content of the present invention is
0.02~0.06%, it is preferably 0.03~0.05%, meets the needs of steel is to deoxidier.
Further, the low yield strength cold rolling high strength steel plate, is mainly made of ferrite and bainite, it is surrendered
Intensity is 230~260MPa, and tensile strength is 400~440MPa, and elongation is 40.0~43.0%.
Further, the low yield strength cold rolling high strength steel plate, is made with the following method：
(1) smelting procedure：A, according to chemical composition mass percent smelting steel；B, the steel that a steps are smelted is cast as slab；
(2) hot-rolled process：Fluid origin slab is obtained into hot rolling after heating, de-scaling, roughing, finish rolling and section cooling
Volume, wherein finish rolling start rolling temperature are 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 645~700 DEG C；
(3) acid rolls process：By above-mentioned hot rolled coil pickling, cold-rolled thin steel strip is then cold rolled to, wherein cold rolling reduction ratio is 60
~74%；
(4) continuous annealing process：By above-mentioned cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made；
Wherein annealing temperature is 780~820 DEG C, and 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature,
Its slow cooling speed is that CR1 is 1~8 DEG C/s, is quickly cooled to 250~350 DEG C of overaging temperature immediately, its rapid cooling speed CR2 is
10~50 DEG C/s, it is finally cooled to room temperature；
Wherein slow cooling speed CR1 preferably 5~8 DEG C/s, rapid cooling speed CR2 preferably 25~35 DEG C/s.
Further, the coiling temperature is 645~670.
Further, the cold rolling reduction ratio is 61~69%.
The present invention also provides the method for manufacturing the above-mentioned more preferable low yield strength cold rolling high strength steel plate of welding performance, the party
Method includes the following steps：
(1) smelting procedure：A, according to chemical composition mass percent smelting steel；B, the steel that a steps are smelted is cast as slab；
(2) hot-rolled process：Fluid origin slab is obtained into hot rolling after heating, de-scaling, roughing, finish rolling and section cooling
Volume, wherein finish rolling start rolling temperature are 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 645~700 DEG C；
(3) acid rolls process：By above-mentioned hot rolled coil pickling, cold-rolled thin steel strip is then cold rolled to, wherein cold rolling reduction ratio is 60
~74%；
(4) continuous annealing process：By above-mentioned cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made；
Wherein annealing temperature is 780~820 DEG C, and 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature,
Its slow cooling speed is that CR1 is 1~5 DEG C/s, is quickly cooled to 250~350 DEG C of overaging temperature immediately, its rapid cooling speed CR2 is
10~50 DEG C/s, it is finally cooled to room temperature.
Further, coiling temperature is 645~670 in the preparation method of low yield strength cold rolling high strength steel plate.
Further, cold rolling reduction ratio is 61~69% in the preparation method of low yield strength cold rolling high strength steel plate.
The embodiment of the present invention is further described with reference to embodiment, is not therefore limited the present invention
System is among the embodiment described scope.
Embodiment 1~4
Low yield strength cold rolling high strength steel plate provided by the invention, its preparation method are as follows：
(1) pass through smelting process, be prepared for the cold rolling high strength steel plate slab of chemical composition as shown in table 1 below：
1 cold rolling high strength steel plate chemical composition (wt.%) of table
| Embodiment | C | Si | Mn | P | S | Als | N |
| 1 | 0.04 | 0.02 | 1.20 | 0.015 | 0.007 | 0.040 | 0.004 |
| 2 | 0.05 | 0.01 | 1.15 | 0.013 | 0.005 | 0.035 | 0.005 |
| 3 | 0.03 | 0.05 | 1.00 | 0.020 | 0.010 | 0.050 | 0.006 |
| 4 | 0.05 | 0.10 | 1.30 | 0.015 | 0.015 | 0.060 | 0.005 |
(2) strand is obtained into hot rolled coil after heating, dephosphorization, hot rolling and section cooling, wherein heating-up temperature 1220~
1260 DEG C, finish rolling start rolling temperature is 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 640~700 DEG C；
Specific hot-rolled process parameter is as shown in table 2 below：
2 high-strength steel hot rolling main technologic parameters of table
| Embodiment | Heating-up temperature/DEG C | Final rolling temperature/DEG C | Finishing temperature/DEG C | Coiling temperature/DEG C | Hot rolled thickness/mm |
| 1 | 1240 | 1050 | 880~910 | 645~670 | 4.5 |
| 2 | 1240 | 1080 | 910~940 | 685~700 | 3.2 |
| 3 | 1240 | 1100 | 880~910 | 645~670 | 2.8 |
| 4 | 1240 | 1000 | 910~940 | 670~700 | 4.8 |
(3) Thin Strip Steel will after hot rolled coil pickling, be cold rolled to, wherein embodiment 1, embodiment 2, embodiment 3 and embodiment 4
Cold rolling reduction ratio is respectively 66.7%, 68.8%, 74.0%, 61.3%.
(4) cold-rolled thin steel strip is made required product after continuous annealing process is handled, wherein annealing temperature for 780~
820 DEG C, 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature, its slow cooling speed CR1 is 1~5 DEG C/s, immediately
250~350 DEG C of overaging temperature is quickly cooled to, its rapid cooling speed CR2 is 10~50 DEG C/s, is finally cooled to room temperature.Specifically
Continuous annealing process parameter is as shown in table 3：
3 continuous annealing main technologic parameters of table
Its microstructure of cold rolling high-strength steel prepared through above-mentioned technique is as shown in Fig. 2, its mechanical property is as shown in table 4 below：
The 4 high-strength steel mechanical property of cold rolling of the present invention of table
| Embodiment | Yield strength/MPa | Tensile strength/MPa | Elongation/% | Yield tensile ratio |
| 1 | 239 | 413 | 41.5 | 0.58 |
| 2 | 254 | 428 | 40.0 | 0.59 |
| 3 | 236 | 436 | 40.6 | 0.54 |
| 4 | 243 | 405 | 42.3 | 0.60 |
The result shows that cold rolling high-strength steel microstructure prepared by the present invention is made of ferrite and bainite, have excellent
Mechanical property and forming property, its yield strength (230~260MPa) and yield tensile ratio (≤0.60) are relatively low, tensile strength
(400-440MPa) and elongation (40.0-43.0%) are higher.
Claims (8)
1. low yield strength cold rolling high strength steel plate, it is characterised in that chemical composition mass percent：C：0.03~0.05%, Si
≤ 0.05%, Mn：1.00~1.15%, Als：0.03~0.05%, P≤0.015%, S≤0.010%, N≤0.0050%, surplus are
Fe and inevitable impurity；
The low yield strength cold rolling high strength steel plate is made with the following method：
（1）Smelting procedure：A, according to chemical composition mass percent smelting steel；B, the steel that a steps are smelted is cast as slab；
（2）Hot-rolled process：Fluid origin slab is obtained into hot rolled coil after heating, de-scaling, roughing, finish rolling and section cooling,
Wherein finish rolling start rolling temperature is 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 645~700 DEG C；
（3）Acid rolls process：By above-mentioned hot rolled coil pickling, be then cold rolled to cold-rolled thin steel strip, wherein cold rolling reduction ratio for 60~
74%；
（4）Continuous annealing process：By above-mentioned cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made；
Wherein annealing temperature is 780~820 DEG C, and 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature, it is slow
Cooling rate rate is that CR1 is 5~8 DEG C/s, is quickly cooled to 250~350 DEG C of overaging temperature immediately, its rapid cooling speed CR2 for 10~
50 DEG C/s, it is finally cooled to room temperature.
2. low yield strength cold rolling high strength steel plate according to claim 1, it is characterised in that the rapid cooling speed CR2
For 25~35 DEG C/s.
3. low yield strength cold rolling high strength steel plate according to claim 1 or 2, it is characterised in that mainly by ferrite and
Bainite forms, its yield strength is 230~260MPa, and tensile strength is 400~440MPa, and elongation is 40.0~43.0%,
Yield tensile ratio≤0.60.
4. the low yield strength cold rolling high strength steel plate according to right wants 1, it is characterised in that the coiling temperature for 645 ~
670℃。
5. the low yield strength cold rolling high strength steel plate according to right wants 1, it is characterised in that the cold rolling reduction ratio is 61
~69%.
6. the preparation method of the low yield strength cold rolling high strength steel plate described in claim 1, it is characterised in that including following step
Suddenly：
（1）Smelting procedure：A, according to chemical composition mass percent smelting steel；B, the steel that a steps are smelted is cast as slab；
（2）Hot-rolled process：Fluid origin slab is obtained into hot rolled coil after heating, de-scaling, roughing, finish rolling and section cooling,
Wherein finish rolling start rolling temperature is 1000~1100 DEG C, and finishing temperature is 880~940 DEG C, and coiling temperature is 645~700 DEG C；
（3）Acid rolls process：By above-mentioned hot rolled coil pickling, be then cold rolled to cold-rolled thin steel strip, wherein cold rolling reduction ratio for 60~
74%；
（4）Continuous annealing process：By above-mentioned cold-rolled thin steel strip continuous annealing, cold rolling high strength steel plate is made；
Wherein annealing temperature is 780~820 DEG C, and 630~680 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature, it is slow
Cooling rate rate is that CR1 is 5~8 DEG C/s, is quickly cooled to 250~350 DEG C of overaging temperature immediately, its rapid cooling speed CR2 for 10~
50 DEG C/s, it is finally cooled to room temperature.
7. the preparation method of low yield strength cold rolling high strength steel plate according to claim 6, it is characterised in that the volume
It is 645 ~ 670 DEG C to take temperature.
8. the preparation method of low yield strength cold rolling high strength steel plate according to claim 6, it is characterised in that in described
Cold rolling reduction ratio is 61~69%.
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| CN108754307B (en) * | 2018-05-24 | 2020-06-09 | 山东钢铁集团日照有限公司 | Method for producing economical cold-rolled DP780 steel with different yield strength grades |
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