CN103205636B - The production method of the continuous yield band steel of low-carbon bainite - Google Patents
The production method of the continuous yield band steel of low-carbon bainite Download PDFInfo
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- CN103205636B CN103205636B CN201310135190.3A CN201310135190A CN103205636B CN 103205636 B CN103205636 B CN 103205636B CN 201310135190 A CN201310135190 A CN 201310135190A CN 103205636 B CN103205636 B CN 103205636B
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Abstract
The invention discloses the production method of the continuous yield band steel of a kind of low-carbon bainite, comprise smelting and add casting process and rolling adds process of cooling.In the present invention, the feature of low-carbon bainite continuous yield band steel is stress strain curve is continuous surrender, without obvious yield-point; The tensile strength of the continuous yield band steel of low-carbon bainite is 600 ~ 750MPa, and not containing the expensive element such as Mo, V in material, lower than equality strength conventional steel iron alloy content.
Description
Technical field
The present invention relates to a kind of band steel production technology, specifically, relate to the production method of the continuous yield band steel of a kind of low-carbon bainite.
Background technology
Automobile high-strength sheet steel is the Hi-Stren steel adding the microalloy elements such as Mo, Nb, V, Ti based on C-Mn steel.Along with the development of automotive light weight technology, 600MPa higher level high-strength steel increases gradually at the consumption of body of a motor car.In novel passenger car and heavy-load automobile, the intensity of bottom girder, crossbeam and strong beam steel thereof is progressively promoted to 600MPa from 510MPa, even more than 700MPa.Current domestic tensile strength is greater than the automobilesheet steel of more than 600MPa level, Mo-V-Nb or Mo-Nb-Ti of employing alloying is produced more, and general Mo, V element and alloying element content high cost containing high price significantly increases.The current mode of production, after coil of strip rolling, its coiling temperature is high temperature coiling, and schedule of reinforcement mainly by refined crystalline strengthening and precipitation strength, generally exists yield-point.
Summary of the invention
Institute of the present invention technical solution problem is to provide the production method of the continuous yield band steel of a kind of low-carbon bainite, and the material of production is not containing the expensive element such as Mo, V, and the stress strain curve of material is surrender continuously, without obvious yield-point.
Technical scheme is as follows:
The production method of the continuous yield band steel of a kind of low-carbon bainite, comprise smelting and add casting process and rolling adds process of cooling, producing the band steel chemical composition obtained is by weight percentage: C 0.06-0.09%, Si0.15-0.30%, Mn 1.4-1.6%, P≤0.020%, S≤0.010%, Alt 0.020-0.060%, Nb+Ti≤0.13%, and surplus is Fe and inevitable impurity; Described smelting process adopts full guard pouring technology; Ladle adopts long nozzle hydrogenation envelope to tundish protection, utilizes seal washer and hydrogen envelope to prevent Air infitration; The tundish of casting process protects the connection hydrogenation of employing submerged nozzle to seal to the beam of crystallizer, and controls P≤0.020%, S≤0.010%, [O]≤40ppm, [the N]≤60ppm of strand; The described operation of rolling adopts CSP mode to produce, and rolling adopts seven frame tandem rolling mode of manufacture, front twice rolling draft >=40%, and finishing temperature control is at 820 ~ 860 DEG C; Cooling adopts the strong cold two-stage cooling mode in section cooling+rear portion, front end, and section cooling speed control is at 10-20 DEG C/S, and strong cold speed of cooling controls to be at least 80 DEG C/S, and oiler temperature control is within the scope of 150-350 DEG C.
Further, by weight percentage, Nb is 0.020-0.050%, Ti is 0.040-0.080% to chemical composition.
The technology of the present invention effect comprises:
1, in the present invention, the feature of low-carbon bainite continuous yield band steel is stress strain curve is continuous surrender, without obvious yield-point.
2, in the present invention, the tensile strength of the continuous yield band steel of low-carbon bainite is 600 ~ 750MPa, and not containing the expensive element such as Mo, V in material, lower than equality strength conventional steel iron alloy content.
3, in the present invention, production cost is low, adopts controlled cooling technique, and realize the transformation of tissue and the lifting of intensity, can stably produce the low cost hot rolled strip of surrender continuously, thickness specification is 3.5-8.0mm, and tensile strength can reach 600MPa-750MPa.
Accompanying drawing explanation
Fig. 1 is the metallograph of the continuous yield band steel of low-carbon bainite in the present invention.
Embodiment
The step of producing the continuous yield band steel of 600 ~ 750MPa low-carbon bainite comprises smelting+continuous casting and rolling+cooling two processes, specific as follows:
Step 1: smelting+continuous casting
Smelt and adopt full guard pouring technology, namely ladle adopts long nozzle hydrogenation envelope to tundish protection, utilizes seal washer and hydrogen envelope to prevent Air infitration; The tundish of casting process, to the connection hydrogenation envelope of beam protection employing SEN (submerged nozzle) of crystallizer, controls P≤0.020%, S≤0.010%, [O]≤40ppm, [the N]≤60ppm of strand.
Casting process adopts dynamic soft reduction technology, the segregation of effective control center and center porosity.
Step 2: rolling+cooling
Adopt CSP mode to produce, rolling adopts seven frame tandem rolling mode of manufacture, and rolling adopts 7 passage tandem rollings.Front twice rolling draft >=40%, finishing temperature control is at 820 ~ 860 DEG C.
Cooling after the operation of rolling adopts the strong cold two-stage cooling mode in section cooling+rear portion, front end, and section cooling speed control is at 10-20 DEG C/S, and cold but speed control is at 80 DEG C/more than S by force, and oiler temperature control is within the scope of 150-350 DEG C.
After said process, obtain the continuous yield band steel of low-carbon bainite that tensile strength is 600 ~ 750MPa, its chemical composition is by weight percentage: C 0.06-0.09%, Si 0.15-0.30%, Mn 1.4-1.6%, P≤0.020%, S≤0.010%, Alt 0.020-0.060%, and surplus is Fe and inevitable impurity.
In order to strengthen the property further, on above-mentioned C-Mn base steel plinth, compound adds Nb, Ti microalloy element, and Nb+Ti≤0.13%, preferred chemical composition is by weight percentage: Nb 0.020-0.050%, Ti0.040-0.080%.
As shown in Figure 1, be the metallograph of the continuous yield band steel of low-carbon bainite in the present invention.
This low-carbon bainite steel be organized as bainite+a small amount of ferrite and carbonization precipitate, fully utilized phase transformation strengthening and precipitation strength two kinds of means.Reduce cooling intensity or increase Nb, Ti composition in design alloys range, can yield strength be increased, to regulate yield tensile ratio, to adapt to the needs of different machining deformation equipment.
Below in conjunction with actual production process, technical solution of the present invention is described further.
Desulfurizing iron, 210t converter smelting, the refining of LF stove is adopted at steelworks, slab thickness is 57 ~ 72mm, be 57 ~ 72mm by thickness, length is that the slab of 980 ~ 1560mm delivers to process furnace and hot tandem, after 7 frame hot continuous rollings, adopt the hot continuous rolling mode of production of controlled rolling and controlled cooling to produce and obtain the continuous yield band steel of low-carbon bainite that tensile strength is 600 ~ 750MPa.
Embodiment 1
Adopt desulfurizing iron, 210t converter smelting, the refining of LF stove at steelworks, make the chemical composition in steel as shown in table 1 after process, surplus is Fe and is inevitably mingled with.
Table 1 chemical composition wt% (weight percent)
The continuous casting of molten steel base section thickness required is 57mm, be that process furnace delivered to by the slab of 1200mm by section thickness 57mm, width, Heating temperature is 1150 DEG C, hot tandem rolling sent into by slab after heating, two frame draft >=40% before hot tandem, section cooling 15 DEG C/s, rapid cooling 80 DEG C/s, coiling temperature 330 DEG C, finished product thickness 5.0mm.
After testing, the performance of the continuous yield band steel of low-carbon bainite: tensile strength 710MPa, yield strength 480MPa, unit elongation A50 is 26%.
Embodiment 2
Through desulfurizing iron, 210t converter smelting, the refining of LF stove, make the chemical composition in steel as shown in table 2 after process, surplus is Fe and is inevitably mingled with.
Table 2 chemical composition wt% (weight percent)
Thickness of strand 70mm, process furnace sent into by the slab that thickness is 70mm, width is 1350mm, furnace temp 1120 DEG C, slab after heating is sent into hot tandem, two frame draft >=40% before hot tandem, stream cooling 16 DEG C/s, rapid cooling 85 DEG C/s, coiling temperature 300 DEG C, finished product thickness 6.0mm.
After testing, the performance of the continuous yield band steel of low-carbon bainite: tensile strength 640MPa, yield strength 460MPa, unit elongation A50 is 28%.
Claims (2)
1. the production method of the continuous yield band steel of low-carbon bainite, it is characterized in that, comprise smelting and add casting process and rolling adds process of cooling, producing the band steel chemical composition obtained is by weight percentage: C 0.06-0.09%, Si 0.15-0.30%, Mn 1.4-1.6%, P≤0.020%, S≤0.010%, Alt0.020-0.060%, Nb+Ti≤0.13%, and surplus is Fe and inevitable impurity; Described smelting process adopts full guard pouring technology; Ladle adopts long nozzle hydrogenation envelope to tundish protection, utilizes seal washer and hydrogen envelope to prevent Air infitration; The tundish of casting process protects the connection hydrogenation of employing submerged nozzle to seal to the beam of crystallizer, and controls P≤0.020%, S≤0.010%, [O]≤40ppm, [the N]≤60ppm of strand; The described operation of rolling adopts CSP mode to produce, and rolling adopts seven frame tandem rolling mode of manufacture, front twice rolling draft >=40%, and finishing temperature control is at 820 ~ 860 DEG C; Cooling adopts the strong cold two-stage cooling mode in section cooling+rear portion, front end, and section cooling speed control is at 10-20 DEG C/S, and cold but speed control is at least 80 DEG C/S by force, and oiler temperature control is within the scope of 150-350 DEG C.
2. the production method of the continuous yield band steel of low-carbon bainite as claimed in claim 1, it is characterized in that, by weight percentage, Nb is 0.020-0.050%, Ti is 0.040-0.080% to chemical composition.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201310135190.3A CN103205636B (en) | 2013-04-18 | 2013-04-18 | The production method of the continuous yield band steel of low-carbon bainite |
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| CN201310135190.3A CN103205636B (en) | 2013-04-18 | 2013-04-18 | The production method of the continuous yield band steel of low-carbon bainite |
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| CN103205636B true CN103205636B (en) | 2015-08-26 |
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| JP3869747B2 (en) * | 2002-04-09 | 2007-01-17 | 新日本製鐵株式会社 | High-strength steel plate, high-strength steel pipe and manufacturing method excellent in deformation performance |
| EP2020451A1 (en) * | 2007-07-19 | 2009-02-04 | ArcelorMittal France | Method of manufacturing sheets of steel with high levels of strength and ductility, and sheets produced using same |
| CN101925685B (en) * | 2008-07-30 | 2013-01-02 | 新日本制铁株式会社 | High-strength thick steel products excellent in toughness and weldability, high-strength ultra-thick h shape steel and processes for manufacturing both |
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