CN106011643B - A kind of tensile strength 590MPa grades of cold-rolled biphase steels and preparation method thereof - Google Patents

A kind of tensile strength 590MPa grades of cold-rolled biphase steels and preparation method thereof Download PDF

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CN106011643B
CN106011643B CN201610545412.2A CN201610545412A CN106011643B CN 106011643 B CN106011643 B CN 106011643B CN 201610545412 A CN201610545412 A CN 201610545412A CN 106011643 B CN106011643 B CN 106011643B
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cold
rolled
temperature
tensile strength
rolled biphase
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CN106011643A (en
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郑之旺
邝春福
徐权
张功庭
王敏莉
余灿生
于秀
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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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
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • 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
    • 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
    • C21D2211/008—Martensite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials 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 invention belongs to high strength steel technical field, and in particular to a kind of tensile strength 590MPa grades of cold-rolled biphase steels and preparation method thereof.A kind of tensile strength 590MPa grades of cold-rolled biphase steels of the present invention, are made of following weight percent composition：C：0.06~0.10%, Si：0.26~0.60%, Mn：1.20~1.60%, Cr：0.10~0.45%, Al：0.02~0.06%, P≤0.020%, S≤0.015%, N≤0.006%, surplus are Fe and inevitable impurity.Cold-rolled biphase steel production cost of the present invention is low, and forming property is excellent, its yield strength and yield tensile ratio are low；In addition, C, Mn content reduce, while substitute Mn with trace Cr, to ensure that steel has good quenching degree, carbon equivalent is relatively low, and welding performance and processability are preferable.

Description

A kind of tensile strength 590MPa grades of cold-rolled biphase steels and preparation method thereof
Technical field
The invention belongs to high strength steel technical field, and in particular to a kind of tensile strength 590MPa grades of cold-rolled biphase steels and its Preparation method.
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 Phase steel has the characteristics that low yield strength, high-tensile and excellent plasticity, becomes 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, the competition in high-strength steel market Also more and more fierce, the dual phase steel of low-cost and high-performance has become the target that each enterprise is pursued, of great interest.
Patent (CN 102747275A) discloses Large strain and strengthens performance cold-rolled biphase steel and its production method, its chemistry Percentage composition is：C：0.10~0.15%, Mn：1.0~2.0%, Al：1.0~2.0%, Mo：0.1~0.2%, surplus is Fe and inevitable impurity；By 800~840 DEG C of finish to gauges, 600-650 DEG C batch, 810~850 DEG C insulation, 260~280 DEG C of mistakes Ageing treatment, has obtained the cold-rolled biphase steel that tensile strength is more than 600MPa.Although pass through its chemical composition and producer legal system Standby cold-rolled biphase steel has excellent mechanical property, but yield strength is higher, influences the forming property of material.Due to needing to add Increasing amount Al, Mo, not only so that production cost substantially increases, continuous casting and rolling difficulty improve.Cause in addition, C, Mn content increase Cold-rolled biphase steel welding performance declines, and finally necessarily affects extensive use of the dual phase steel on automobile.
Patent (CN 102758131A) discloses a kind of production method of 600MPa grades of cold-rolled biphase steel plate, its chemistry into Point percentage is：C：0.06~0.09%, Si：0.40~0.60%, Mn：1.65~1.75%, Al：0.025~0.060%, P ≤ 0.010%, S≤0.015%, N≤0.004%, surplus are Fe and inevitable impurity；Pass through 820~880 DEG C of finish to gauges, 620 ~680 DEG C batch, 800~840 DEG C of insulations, 650~700 DEG C of slow cooling, 200~300 DEG C of Wetted constructures, obtained tensile strength Cold-rolled biphase steel more than 600MPa.The cold-rolled biphase steel production cost produced by this method is relatively low, and tensile strength can reach To 600MPa.However, the dual phase steel yield strength is higher, its forming property is seriously affected；Si, Mn content are higher at the same time, make it Welding performance declines.
Patent (CN 103952523A) discloses a kind of continuous annealing side of martensite ferrite dual phase steel cold rolled sheet Method, its chemical composition percentage are：C：0.06~0.09%, Si：0.18~0.49%, Mn：1.65~1.90%, Cr：0.15 ~0.18%, Als：0.03~0.05%, P≤0.02%, S≤0.004%, surplus are Fe and inevitable impurity；Pass through 760 ~840 DEG C of insulations, 660~700 DEG C of slow cooling, 60~100 DEG C/s be cooled to soon 250~270 DEG C, 30~100 DEG C/s reheatings extremely It is 695-710MPa cold-rolled biphase steels that the method for 310~380 DEG C of Wetted constructures, which obtains tensile strength,.This method produces cold Rolling dual phase steel has excellent a comprehensive mechanical property and forming property, however continuous annealing process it is complicated, it is necessary to quickly cooling and Quick heating, it is higher to equipment Requirement；Microalloy element addition at the same time is more so that the production cost increases.
Patent (CN 101857942A) discloses a kind of tensile strength 590MPa grades of hot rolled steel plate and its production method. The hot rolled steel plate, is made of the component of following percentage by weight：C 0.05~0.10%, Si 0.10~0.25%, Mn 1.10~1.50%, P 0.03~0.08%, S≤0.008%, Cr 0.50~0.80%, Als 0.015~0.065%, it is remaining Measure as iron and inevitable impurity.Although the tensile strength in the patent reaches 590MPa grades, its yield strength is higher, Yield tensile ratio ＞ 0.60, processability is bad；And its rolling mill practice is by the way of hot rolling, cost higher.
The content of the invention
The technical problems to be solved by the invention be to provide a kind of yield strength and carbon equivalent are low, tensile strength is high, production Cost is low and the good cold-rolled biphase steel of surface quality.
A kind of tensile strength 590MPa grades of cold-rolled biphase steels, are made of following weight percent composition：C：0.06~ 0.10%, Si：0.26~0.60%, Mn：1.20~1.60%, Cr：0.10~0.45%, Al：0.02~0.06%, P≤ 0.020%, S≤0.015%, N≤0.006%, surplus are Fe and inevitable impurity.
Further, as preferred technical solution, a kind of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels, by with Lower weight percent composition composition：C：0.07~0.09%, Si：0.30~0.40%, Mn：1.30~1.5%, Cr：0.2~ 0.4%, Al：0.03~0.05%, P≤0.011%, S：0.005~0.006%, N：0.004~0.005%, surplus for Fe and Inevitable impurity.
A kind of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels, its yield strength is 290~330MPa, and tensile strength is 600~650MPa, elongation A80For 23~27%, yield tensile ratio is≤0.50.
The present invention also provides a kind of preparation method of tensile strength 590MPa grades of cold-rolled biphase steels.
A kind of preparation method of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels, comprises the following steps：
A, smelting process：Smelting is carried out according to the weight percent composition of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels Refining, is cast as slab, obtains strand；
B, hot rolling technology：Strand is obtained into hot rolled coil after heating, dephosphorization, roughing, finish rolling and section cooling；It is wherein smart Start rolling temperature is rolled for 1000~1100 DEG C, and finishing temperature is 850~950 DEG C, and coiling temperature is 600~700 DEG C；
C, sour mutual aid system devised for poor peasants skill：By hot rolled coil, the cold rolling after overpickling, obtains cold-rolled thin steel strip；Wherein, cold rolling reduction ratio is 50 ~70%；
D, continuous annealing process：By cold-rolled thin steel strip after continuous annealing, cold-rolled biphase steel is obtained；Wherein, annealing temperature Spend for 780~820 DEG C, 650~700 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, 250~350 DEG C of overaging temperature is quickly cooled to immediately, its rapid cooling speed CR2 is 10~50 DEG C/s, is finally cooled to Room temperature.
Further, as preferred technical solution, a kind of above-mentioned system of tensile strength 590MPa grades of cold-rolled biphase steels Finish rolling start rolling temperature is 1050~1080 DEG C in Preparation Method, wherein b step.
Further, as preferred technical solution, a kind of above-mentioned system of tensile strength 590MPa grades of cold-rolled biphase steels Cold rolling reduction ratio is 57~63% in Preparation Method, wherein step c.
Further, as preferred technical solution, a kind of above-mentioned system of tensile strength 590MPa grades of cold-rolled biphase steels Annealing temperature is 800~810 DEG C in Preparation Method, wherein Step d, 650~680 DEG C of rapid cooling start temperature, overaging temperature 270~ 300 DEG C, its rapid cooling speed CR2 is 25~35 DEG C/s.
Compared with prior art, the present invention has the advantages that：
(1) low production cost：The Mo of costliness is not added with, while Mn contents are relatively low；
(2) excellent formability energy：290~330MPa of yield strength, yield tensile ratio≤0.50, its value is than relatively low；
(3) good welds performance：C, Mn contents reduce, while substitute Mn with trace Cr, to ensure that steel has good quench Permeability, carbon equivalent is relatively low, and welding performance is preferable.
Brief description of the drawings
Fig. 1 is the continuous annealing process schematic diagram of cold-rolled biphase steel of the present invention；
Fig. 2 is the microstructure morphology (F of cold-rolled biphase steel of the present invention：Ferrite；M：Martensite).
Embodiment
A kind of tensile strength 590MPa grades of cold-rolled biphase steels, are made of following weight percent composition：C：0.06~ 0.10%, Si：0.26~0.60%, Mn：1.20~1.60%, Cr：0.10~0.45%, Al：0.02~0.06%, P≤ 0.020%, S≤0.015%, N≤0.006%, surplus are Fe and inevitable impurity.
Further, as preferred technical solution, a kind of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels, by with Lower weight percent composition composition：C：0.07~0.09%, Si：0.30~0.40%, Mn：1.30~1.5%, Cr：0.2~ 0.4%, Al：0.03~0.05%, P≤0.011%, S：0.005~0.006%, N：0.004~0.005%, surplus for Fe and Inevitable impurity.
Design of alloy principle of the present invention is as follows：
Carbon：C determines the intensity, plasticity and forming property of steel plate as one of most important component of dual phase steel.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 dual phase steel 0.02%；When C content is excessive, the plasticity and welding performance of dual phase steel decline, and 0.20% is generally not more than in dual phase steel.Therefore, C content of the present invention is 0.06~0.10%, is preferably 0.07~0.09%.
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 Dephosphorization difficulty is added.Therefore, Si contents of the present invention are 0.26~0.60%, are preferably 0.30~0.40%.
Manganese：Mn is common solution strengthening element in good deoxidier and desulfurizing agent, and steel, in dual phase steel 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.Therefore, Mn contents are 1.20~1.60% in the present invention, are preferably 1.30~1.50%.
Chromium：Cr can significantly postpone pearlite and bainite transformation, austenite is fully changed into martensitic structure, so that Obtain higher tensile strength.Since Cr compared with Mo has obvious cost advantage, so largely making an addition in cold-rolled biphase steel.Cause This, in the present invention, Cr contents are 0.10~0.45%, are preferably 0.20~0.40%.
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.Therefore, in the present invention Al content is 0.02~0.06%, is preferably 0.03~0.05%.
A kind of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels, its yield strength is 290~330MPa, and tensile strength is 600~650MPa, elongation A80For 23~27%, yield tensile ratio is≤0.50.
The present invention also provides a kind of preparation method of tensile strength 590MPa grades of cold-rolled biphase steels.
A kind of preparation method of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels, comprises the following steps：
A, smelting process：Smelting is carried out according to the weight percent composition of above-mentioned tensile strength 590MPa grades of cold-rolled biphase steels Refining, is cast as slab, obtains strand；
B, hot rolling technology：Strand is obtained into hot rolled coil after heating, dephosphorization, roughing, finish rolling and section cooling；It is wherein smart Start rolling temperature is rolled for 1000~1100 DEG C, and finishing temperature is 850~950 DEG C, and coiling temperature is 600~700 DEG C；
C, sour mutual aid system devised for poor peasants skill：By hot rolled coil, the cold rolling after overpickling, obtains cold-rolled thin steel strip；Wherein, cold rolling reduction ratio is 50 ~70%；
D, continuous annealing process：By cold-rolled thin steel strip after continuous annealing, cold-rolled biphase steel is obtained；Wherein, annealing temperature Spend for 780~820 DEG C, 650~700 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, 250~350 DEG C of overaging temperature is quickly cooled to immediately, its rapid cooling speed CR2 is 10~50 DEG C/s, is finally cooled to Room temperature.
Further, as preferred technical solution, a kind of above-mentioned system of tensile strength 590MPa grades of cold-rolled biphase steels Finish rolling start rolling temperature is 1050~1080 DEG C in Preparation Method, wherein b step.
Further, as preferred technical solution, a kind of above-mentioned system of tensile strength 590MPa grades of cold-rolled biphase steels Cold rolling reduction ratio is 57~63% in Preparation Method, wherein step c.
Further, as preferred technical solution, a kind of above-mentioned system of tensile strength 590MPa grades of cold-rolled biphase steels Annealing temperature is 800~810 DEG C in Preparation Method, wherein Step d, 650~680 DEG C of rapid cooling start temperature, overaging temperature 270~ 300 DEG C, its rapid cooling speed CR2 is 25~35 DEG C/s.
The present invention substitutes part Mn to postpone pearlite and bainite transformation with trace Cr, while improves cold-rolled biphase steel Quenching degree；Solution strengthening and the precipitation strength effect of Cr is weak compared with Mn, so cold-rolled biphase steel has low yield strength；In addition Mn contains Amount reduces so that the welding performance of cold-rolled biphase steel significantly improves.Cold-rolled biphase steel forming property and welding prepared by the present invention Function admirable, has significant economic benefit and social benefit.
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
590MPa grades of low yield strength cold-rolled biphase steel preparation method provided by the invention is as follows with technique：
(1) pass through smelting process, be prepared for the dual phase steel slab of chemical composition as shown in table 1 below：
1 two-phase steel chemical composition (wt.%) of table
Numbering C Si Mn P S Als Cr N
DP1 0.08 0.40 1.40 0.011 0.006 0.040 0.29 0.004
DP2 0.09 0.30 1.45 0.011 0.005 0.035 0.32 0.005
(2) strand is obtained into hot rolled coil after heating, dephosphorization, hot rolling and section cooling, wherein finish rolling start rolling temperature is 1000~1100 DEG C, finishing temperature is 850~950 DEG C, and coiling temperature is 600~700 DEG C；Specific hot-rolled process parameter such as following table Shown in 2：
2 dual phase steel hot rolling main technologic parameters of table
Numbering Heating-up temperature/DEG C Final rolling temperature/DEG C Finishing temperature/DEG C Coiling temperature/DEG C Hot rolled thickness/mm
DP1 1240 1050 850~900 600~650 4.2
DP2 1240 1080 900~950 650~700 3.2
(3) Thin Strip Steel will after hot rolled coil pickling, be cold rolled to, the cold rolling reduction ratio of wherein DP1 and DP2 are respectively 57.1% He 62.5%.
(4) cold-rolled thin steel strip is made required product after continuous annealing process is handled, wherein annealing temperature for 780~ 820 DEG C, 650~700 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, with 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.Tool Body continuous annealing process parameter is as shown in table 3：
3 continuous annealing main technologic parameters of table
Numbering Annealing temperature/DEG C Slow cooling end temp/DEG C Overaging temperature/DEG C Rapid cooling speed/DEG C/s
DP1 800 680 300 25
DP2 810 650 270 35
Its microstructure of cold-rolled biphase steel prepared through above-mentioned technique is as shown in Fig. 2, its mechanical property is as shown in table 4 below：
The cold-rolled biphase steel mechanical property of the present invention of table 4 is compared with prior art
Note：Ceq=C+Si/20+Mn/30+2P+4S
The result shows that cold-rolled biphase steel microstructure prepared by the present invention is made of ferrite and martensite, it surrenders strong Spend (290~330MPa) and yield tensile ratio (≤0.50) is relatively low, tensile strength (600-650MPa) and elongation (23.0~ 27.0%) it is higher.Cold-rolled biphase steel C, Mn content is relatively low, so with excellent forming property and welding performance.

Claims (4)

  1. A kind of 1. tensile strength 590MPa grades of cold-rolled biphase steels, it is characterised in that：It is made of following weight percent composition：C： 0.07~0.09%, Si：0.30~0.40%, Mn：1.30~1.45%, Cr：0.2~0.4%, Al：0.03~0.05%, P ≤ 0.011%, S：0.005~0.006%, N：0.004~0.005%, surplus is Fe and inevitable impurity；
    The preparation method of the tensile strength 590MPa grades of cold-rolled biphase steels comprises the following steps：
    A, smelting process：Smelted according to the weight percent composition of cold-rolled biphase steel as described above, be cast as slab, obtained Strand；
    B, hot rolling technology：Strand is obtained into hot rolled coil after heating, dephosphorization, roughing, finish rolling and section cooling；Wherein finish rolling is opened Temperature is rolled for 1050~1080 DEG C, and finishing temperature is 850~950 DEG C, and coiling temperature is 600~700 DEG C；
    C, sour roll process：By hot rolled coil, the cold rolling after overpickling, obtains cold-rolled thin steel strip；Wherein, cold rolling reduction ratio for 50~ 70%；
    D, continuous annealing process：By cold-rolled thin steel strip after continuous annealing, cold-rolled biphase steel is obtained；Wherein, annealing temperature is 780~820 DEG C, 650~700 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature, its slow cooling speed CR1 for 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, is finally cooled to room Temperature；
    The yield strength of the tensile strength 590MPa grades of cold-rolled biphase steels is 290~330MPa, tensile strength for 600~ 650MPa, elongation A80For 23~27%, yield tensile ratio is≤0.50.
  2. A kind of 2. preparation method of tensile strength 590MPa grades of cold-rolled biphase steels described in claim 1, it is characterised in that including with Lower step：
    A, smelting process：According to claim 1, the weight percent composition of cold-rolled biphase steel is smelted, and is cast as plate Base, obtains strand；
    B, hot rolling technology：Strand is obtained into hot rolled coil after heating, dephosphorization, roughing, finish rolling and section cooling；Wherein finish rolling is opened Temperature is rolled for 1050~1080 DEG C, and finishing temperature is 850~950 DEG C, and coiling temperature is 600~700 DEG C；
    C, sour roll process：By hot rolled coil, the cold rolling after overpickling, obtains cold-rolled thin steel strip；Wherein, cold rolling reduction ratio for 50~ 70%；
    D, continuous annealing process：By cold-rolled thin steel strip after continuous annealing, cold-rolled biphase steel is obtained；Wherein, annealing temperature is 780~820 DEG C, 650~700 DEG C of rapid cooling start temperature is slowly cooled to from annealing temperature, its slow cooling speed CR1 for 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, is finally cooled to room Temperature.
  3. A kind of 3. preparation method of tensile strength 590MPa grades of cold-rolled biphase steels according to claim 2, it is characterised in that：c Cold rolling reduction ratio is 57~63% in step.
  4. A kind of 4. preparation method of tensile strength 590MPa grades of cold-rolled biphase steels according to claim 2, it is characterised in that：d Annealing temperature is 800~810 DEG C in step, 650~680 DEG C of rapid cooling start temperature, 270~300 DEG C of overaging temperature, its rapid cooling Speed CR2 is 25~35 DEG C/s.
CN201610545412.2A 2016-07-11 2016-07-11 A kind of tensile strength 590MPa grades of cold-rolled biphase steels and preparation method thereof Active CN106011643B (en)

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