Production method of ultra-deep drawing cold-rolled steel strip DC07

Abstract

The invention discloses a production method of an ultra-deep drawing cold-rolled steel strip DC07, and belongs to the technical field of steel metallurgy steelmaking processes. The method comprises the following steps: (1) steelmaking; (2) hot rolling; (3) pickling and rolling; (4) a continuous annealing process; the mass percentage content of the chemical components is that C is less than or equal to 0.0015%; s is less than or equal to 0.01%; 0.10% or less of Mn; p < = 0.008%; s < = 0.0060%; ti is greater than or equal to 0.060 and less than or equal to N is less than or equal to 0.0030%; 0 < = 0.0030%, and the balance Fe and inevitable impurities. And the produced product has lower yield ratio and lower yield strength, is suitable for automobile parts with more complex deformation, and has a good stamping effect. The mechanical properties of the strip steel meet the requirements that the yield strength Rp0.2 is smaller than or equal to 150 MPa, the tensile strength Rm is larger than or equal to 250 MPa, the ductility A80 is larger than or equal to 42%, r90 is larger than or equal to 2.5, and n90 is larger than or equal to 0.21.

Description

Technical Field

[0001] This invention relates to the field of steelmaking technology in iron and steel metallurgy, and in particular to a method for producing ultra-deep drawing cold-rolled steel strip DC07. Background Technology

[0002] Deep-drawing and ultra-deep-drawing steels are widely used in the automotive industry due to their excellent stamping performance. As a key steel grade for manufacturing automotive components, deep-drawing steel is in huge demand. With the rapid development of my country's social economy, the production and models of automobiles are constantly increasing. Simultaneously, with customers' rising demands for automotive quality and increasing competitive pressure within the automotive industry, the market is placing higher demands on deep-drawing products. To better meet the specific needs of the modern automotive industry for ultra-deep-drawing parts, developing products with higher stamping performance levels can enhance the market competitiveness of deep-drawing products and achieve sustainable development in the stamping industry. Summary of the Invention

[0003] The purpose of this invention is to provide a method for producing ultra-deep drawing cold-rolled steel strip DC07. Products produced using this method have a lower yield strength ratio and lower yield strength. User feedback indicates excellent performance, making them suitable for automotive parts with more complex deformation processes, and providing good stamping results. The mechanical properties of the strip steel satisfy: Yield strength R... p0.2 ≤150MPa, tensile strength R m ≥250MPa, elongation A 80 ≥42%, r 90 ≥2.5, n 90 ≥0.21.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] This invention discloses a method for producing ultra-deep drawing cold-rolled steel strip DC07, comprising:

[0006] (1) Steelmaking production process: Smelting - continuous casting production process: KR desulfurization - converter - RH furnace - slab continuous casting; The sulfur content of the molten iron entering the converter is required to be less than 0.005%, and the slag removal area is required to be greater than 95% (the surface of the molten iron is relatively clean after slag removal); Deep decarburization treatment is carried out according to the composition and temperature of the RH steel supplied to the converter; After decarburization, aluminum particles are added for deoxidation and alloying according to the oxygen content, and after circulating for more than 4 minutes, ferromanganese and ferrotitanium alloys are added to adjust the composition; After adjusting the composition, ensure vacuum circulation for ≥6 minutes; The superheat of slab continuous casting is 25~40℃, and the casting speed is controlled at 1.0~1.8m / min;

[0007] (2) Hot rolling production process: billet heating—rough rolling—finish rolling—coiling; billet heating temperature 1170~1200℃, furnace exit temperature 1170~1200℃, rough rolling adopts 3+3 mode 2-stand rolling mill rough rolling, finish rolling adopts 7-stand rolling mill finish rolling, finish rolling temperature is 890~940℃; cooling adopts laminar flow cooling equipment, coiling temperature is 685~735℃;

[0008] (3) Pickling and rolling process: pickling and uncoiling—welding—straightening—pickling—rinsing—drying—edge trimming—continuous rolling mill cold rolling—slitting—coiling; after the hot-rolled steel strip is pickled to remove the surface iron oxide scale, it is cold rolled by a 5-stand cold rolling mill with a cold rolling reduction rate of 75-85%.

[0009] (4) Continuous annealing process: continuous annealing uncoiling—welding—cleaning—entry looper—annealing furnace—exit looper—leveling—inspection—looper—edge trimming—surface inspection—oiling—sampling—coiling—weighing—packaging—warehousing; after uncoiling the cold-hardened steel strip, continuous welding production is carried out, with furnace speed of 140~180m / min, soaking temperature of 800~830℃, and leveling machine elongation of 0.3~0.4%;

[0010] Its chemical composition by mass percentage is C≤0.0015%; Si≤0.01%; Mn≤0.10%; P≤0.008%; S≤0.0060%; 0.060≤Ti≤0.075%; N≤0.0030%; O≤0.0030%, with the remainder being Fe and unavoidable impurities.

[0011] Furthermore, the thickness of the hot-rolled steel strip is 3.5 mm.

[0012] Furthermore, the thickness of the cold-rolled steel strip is 0.7 mm.

[0013] Furthermore, the mass percentage of its chemical composition is C: 0.0012%; Si: 0.004%; Mn: 0.08%; P: 0.006%; S: 0.0050%; Ti: 0.070%; N: 0.0020%; O: 0.0015%, with the remainder being Fe and unavoidable impurities.

[0014] Furthermore, the mass percentage of its chemical composition is C: 0.0010%; Si: 0.003%; Mn: 0.07%; P: 0.007%; S: 0.0054%; Ti: 0.062%; N: 0.0025%; O: 0.0010%, with the remainder being Fe and unavoidable impurities.

[0015] Furthermore, the mass percentage of its chemical composition is C: 0.0013%; Si: 0.004%; Mn: 0.09%; P: 0.006%; S: 0.0050%; Ti: 0.068%; N: 0.0022%; O: 0.0012%, with the remainder being Fe and unavoidable impurities.

[0016] Furthermore, the mass percentage of its chemical composition is C: 0.0013%; Si: 0.004%; Mn: 0.09%; P: 0.005%; S: 0.0045%; Ti: 0.072%; N: 0.0015%; O: 0.0015%, with the remainder being Fe and unavoidable impurities.

[0017] Furthermore, the mechanical properties satisfy: yield strength R p0.2 ≤150MPa, tensile strength R m ≥250MPa, elongation A 80 ≥42%, r 90 ≥2.5, n 90 ≥0.21.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0019] The product manufactured by the method of this invention has a lower yield strength ratio and a lower yield strength. User feedback indicates excellent performance, making it suitable for automotive parts with more complex deformation processes, and providing good stamping results. The mechanical properties of the strip steel meet the following requirements: Yield strength R... p0.2 ≤150MPa, tensile strength R m ≥250MPa, elongation A 80 ≥42%, r 90 ≥2.5, n 90 ≥0.21. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] picture Figure 1 This is a microstructure diagram of Embodiment 1 of the present invention;

[0022] Figure 2 This is an application example diagram of Embodiment 1 of the present invention. Detailed Implementation

[0023] The present invention will be described in detail below through specific embodiments. These embodiments are only intended to help understand the present invention and do not limit the scope of the present invention.

[0024] Example

[0025] Table 4: Chemical Composition (%)

[0026]

[0027] According to the above hot rolling process requirements, the hot rolling thickness is 3.5mm, and the actual process is shown in Table 5.

[0028] Table 5: Rolling Process

[0029] Example Hot-rolled thickness (mm) Finishing rolling temperature (°C) Winding temperature (°C) Example 1 3.5 920 716 Example 2 3.5 925 721 Example 3 3.5 922 725 Example 4 3.5 921 718

[0030] According to the above requirements for continuous annealing, with a strip thickness of 0.7mm, the actual processes for annealing, continuous annealing, and leveling are shown in Table 6.

[0031] Table 6: Continuous Annealing Process

[0032]

[0033] The mechanical properties of the steel strip products obtained through the above process are shown in Table 7. The test methods refer to GB / T228.1.

[0034] Table 7: Mechanical Properties

[0035]

[0036] As shown in Table 7, the mechanical properties of the strip steel satisfy the following: yield strength R p0.2 ≤150MPa, tensile strength R m ≥250MPa, elongation A 80 ≥42%, r 90 ≥2.5, n 90 ≥0.21. Products produced using this method have a lower yield strength ratio and a lower yield strength. User feedback indicates excellent performance, making them suitable for more complex automotive parts with good stamping results. This method can be extended to other parts in new car models, especially those with large deformation and complex shapes, and can also serve as a reference for the use of other deep-drawing automotive steels.

[0037] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for producing an ultra deep-drawing cold-rolled steel strip DC07, characterized in that: Comprise: (1) Steel production process flow: smelting-continuous casting production process flow: KR desulfurization-converter-RH furnace-slab continuous casting; Wherein the sulfur content of the molten iron into the converter is required to be less than 0.005%, and the molten slag cleaning area is required to be greater than 95%; according to the composition and temperature of the molten steel supplied by the converter to the RH, deep decarburization treatment is carried out; after the decarburization is completed, aluminum grain deoxidizing alloy is added according to the oxygen content, and after circulating for more than 4 minutes, manganese iron and titanium iron alloy are added to adjust the composition; after the composition adjustment is completed, the vacuum circulation is ensured to be greater than or equal to 6 minutes; the slab continuous casting superheat is 25-40℃, and the drawing speed is controlled at 1.0-1.8m / min; (2) Hot rolling production process flow: casting blank heating-rough rolling-finish rolling-coiling; the casting blank heating temperature is 1170-1200℃, the discharge temperature is 1170-1200℃, the rough rolling adopts a 3+3 mode 2 rack rolling mill, the finish rolling adopts a 7 rack rolling mill, and the finish rolling final rolling temperature is 890-940℃; the cooling adopts laminar flow cooling equipment, and the coiling temperature is 685-735℃; (3) Pickling rolling process: pickling rolling-unwinding-welding-straightening-pickling-rinsing-drying-edging-cold rolling mill-division-cutting-coiling; after the hot rolled steel strip is pickled to remove the surface iron oxide scale, it is cold rolled through a 5 rack cold rolling mill, and the cold rolling reduction rate is 75-85%; (4) Continuous annealing process: continuous annealing-unwinding-welding-cleaning-inlet loop-annealing furnace-outlet loop-skin pass-checking-loop-edging-surface inspection-oiling-sampling-coiling-weighing-packaging-warehousing; after the cold hard steel strip is unwound, it is continuously produced by welding, the furnace area speed is 140-180m / min, the soaking temperature is 800-830℃, and the skin pass machine elongation is 0.3-0.4%; The mass percentage content of its chemical composition is C≤0.0015%; Si≤0.01%; Mn≤0.10%; P≤0.008%; S≤0.0060%; 0.060≤Ti≤0.075%; N≤0.0030%; O≤0.0030%, and the rest is Fe and inevitable impurities.

2. The method of producing an ultra deep drawing cold-rolled steel strip DC07 according to claim 1, characterized in that: The hot rolled steel strip thickness is 3.5mm.

3. The method of producing ultra deep drawing cold rolled steel strip DC07 according to claim 1, characterized by: The cold rolled steel strip thickness is 0.7mm.

4. The method of producing ultra deep drawing cold-rolled steel strip DC07 according to claim 1, characterized by the fact that: The mass percentage content of its chemical composition is C: 0.0012%; Si: 0.004%; Mn: 0.08%; P: 0.006%; S: 0.0050%; Ti: 0.070%; N: 0.0020%; O: 0.0015%; and the rest is Fe and inevitable impurities.

5. The method of producing ultra deep drawing cold rolled steel strip DC07 according to claim 1, characterized by: The mass percentage content of its chemical composition is C: 0.0010%; Si: 0.003%; Mn: 0.07%; P: 0.007%; S: 0.0054%; Ti: 0.062%; N: 0.0025%; O: 0.0010%; and the rest is Fe and inevitable impurities.

6. The method of producing ultra deep drawing cold rolled steel strip DC07 according to claim 1, characterized by: The mass percentage content of its chemical composition is C: 0.0013%; Si: 0.004%; Mn: 0.09%; P: 0.006%; S: 0.0050%; Ti: 0.068%; N: 0.0022%; O: 0.0012%, and the rest is Fe and inevitable impurities.

7. The method of producing ultra deep drawing cold rolled steel strip DC07 according to claim 1, characterized by: The mass percentage of the chemical components is C: 0.0013%; Si: 0.004%; Mn: 0.09%; P: 0.005%; S: 0.0045%; Ti: 0.072%; N: 0.0015%; O: 0.0015%, and the rest is Fe and inevitable impurities.

8. The method of producing ultra deep drawing cold rolled steel strip DC07 according to claim 1, characterized by: Mechanical properties meet: yield strength R p0.2 ≤ 150 MPa, tensile strength R m ≥ 250 MPa, elongation A 80 ≥ 42%, r 90 ≥ 2.5, n 90 ≥ 0.21.

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