CN104498689A - Low-molybdenum high-strength steel and preparation method thereof - Google Patents
Low-molybdenum high-strength steel and preparation method thereof Download PDFInfo
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- CN104498689A CN104498689A CN201410800873.0A CN201410800873A CN104498689A CN 104498689 A CN104498689 A CN 104498689A CN 201410800873 A CN201410800873 A CN 201410800873A CN 104498689 A CN104498689 A CN 104498689A
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Abstract
The invention relates to low-molybdenum high-strength steel and a preparation method thereof. According to the technical scheme, the method comprises the following steps: performing acid pickling treatment on hot-rolled steel plates, rolling the pickled steel plates according to 4-6 passes by adopting a cold rolling mill unit, rolling to 0.8-1.2mm, thereby obtaining cold-rolled steel sheet strips; heating the cold-rolled steel sheet strips to the temperature of 570-670 DEG C in a vacuum heating furnace at a heating speed of 20-30 DEG C per second, preserving the temperature for 20-40 minutes, cooling to the temperature of 200-230 DEG C at a cooling speed of 5-10 DEG C per second, and performing furnace cooling to room temperature. The hot-rolled steel plate comprises the following chemical components: 0.18-0.20wt% of C, 2.20-2.50wt% of Mn, 1.20-1.40wt% of Si, 0.08-0.12wt% of Mo, less than 0.01wt% of P, less than 0.003wt% of S, less than 0.004wt% of N and the balance of Fe and inevitable impurities; and the thickness of the hot-rolled steel plate is 3-5mm. The low-molybdenum high-strength steel disclosed by the invention has the characteristics of low production cost, simple process and short production period, and the strength and plasticity of the product are well matched.
Description
Technical field
The invention belongs to high-strength steel technical field.Be specifically related to a kind of low molybdenum high-strength steel and preparation method thereof.
Technical background
Along with improving constantly of automobile product level, also day by day improve the requirement of automobile steel, AHSS is widely used gradually at automotive field.For the service requirements mainly high strength of steel and the good plasticity of automobile steel, while namely ensureing that material has high strength, possesses again good impact property.Traditional hot-rolled sheet has the advantage of high strength, but it is poor for the controllability of thickness and precision and surface quality, therefore substitute hot-rolled high-strength plate gradually with the high strength cold rolled steel plate band of Thin Specs and manufacture automobile component, to improve work-ing life, reduce production cost.
" a kind of ultra-high strength cold-rolled steel strip nodularization annealing process " (CN101845540A) patented technology, its chemical composition (wt%) is: C is 0.17 ~ 0.23%, Si is 0.15 ~ 0.35%, Mn is 0.60 ~ 0.90%, S≤0.01%, P≤0.01%, Cr is 0.40 ~ 0.65%, Ni is 0.40 ~ 0.70%, Mo is 0.15 ~ 0.35%, surplus Fe.Though the long unit elongation that can make of annealing time reaches 30%, its tensile strength only has 350 ~ 550MPa, yield strength 300 ~ 400MPa, and for the skeleton manufacturing automotive seat, intensity is obviously not enough.And with the addition of a large amount of alloying elements, do not bring the remarkable improvement of performance, add production cost on the contrary.
" yield strength 980MPa level cold-rolled steel sheet and manufacture method thereof " (CN102925817A) patented technology, its chemical composition (wt%) is: C is 0.08 ~ 0.13%, Si is 0.05 ~ 0.5%, Mn is 1.2 ~ 2.0%, Cr be 0.6 ~ 1.5%, Nb is 0.02 ~ 0.08%, V is 0.04 ~ 0.20%, Ti is 0.08 ~ 0.20%, P≤0.010%, S≤0.005%, Nb, V, Ti choose any one kind of them or multiple, and Alt is 0.02 ~ 0.1%, N≤0.006%, O≤0.004%, all the other are Fe and inevitable impurity.Its annealing temperature selects 650 ~ 680 DEG C, and soaking time is 12 ~ 14h.Although its tensile strength can reach 1000 ~ 1200MPa, its unit elongation is only 6 ~ 12%, requires that higher automobile component is difficult to meet the demands for plasticity and plasticity.A large amount of interpolation alloying element improves production cost, and requires higher to the rolling power of cold mill complex, and energy consumption is larger.
" a kind of ultrahigh strength surface-active steel plate manufacture method and steel plate thereof " (CN103160654A) patented technology, its chemical composition (wt%) is: C is 0.001 ~ 0.5%, Si is 0 ~ 2.0%, Mn is 0.1 ~ 5.0%, Al be 0.02 ~ 2.0%, Cr is 0 ~ 1.50%, Mo is 0 ~ 2.0%, B be 0 ~ 0.01%, V is 0 ~ 1.0%, Ti is 0 ~ 0.5%, Nb is 0 ~ 0.5%, P≤0.05%, S≤0.02%, Ni is 0 ~ 2.0%, and remainder is iron and inevitable impurity.It adopts smelting-continuous casting and hot rolling-cold rolling-annealing process production high strength surfactivity steel plate, although final intensity is higher, with the addition of a large amount of alloying elements, increase substantially production cost, and production technique is too complicated, annealing atmosphere is required strict.The addition of alloying element is depended in the raising of its intensity completely, has certain limitation for the large-scale industrial production of reality.
As can be seen from above-mentioned analysis, for existing high-performance cold rolled automobile sheetsteel, application result is not also very desirable.Plasticity and toughness are difficult to and strength matching, and the too high plasticity of intensity seems again not enough, and the good intensity of plasticity is undesirable again.Or rely on and add a large amount of alloying elements and improve intensity, not only increase production cost, and preparation technology's more complicated, the throughput for existing installation requires higher, and the production cycle is long, suitability for industrialized production is had certain restricted.
Summary of the invention
The present invention is intended to the defect overcoming prior art, and object is to provide the preparation method of a kind of low production cost, technique low molybdenum high-strength steel simple and with short production cycle, mates well with plasticity by the intensity of the low molybdenum high-strength steel prepared by the method.
For achieving the above object, the technical solution used in the present invention is: to the steel plate acid-washing process after hot rolling, then adopts cold mill complex to the steel plate after pickling by 4 ~ 6 passes, is rolling to 0.8 ~ 1.2mm, obtains cold-rolled steel strip; Cold-rolled steel strip is heated to 570 ~ 670 DEG C with the rate of heating of 20 ~ 30 DEG C/s in vacuum furnace, and insulation 20 ~ 40min, is then cooled to 200 ~ 230 DEG C with the speed of cooling of 5 ~ 10 DEG C/s, cools to room temperature with the furnace.
Steel plate chemical composition after described hot rolling and content thereof are: C is 0.18 ~ 0.20wt%, Mn is 2.20 ~ 2.50wt%, Si is 1.20 ~ 1.40wt%, Mo is 0.08 ~ 0.12wt%, P<0.01wt%, S<0.003wt%, N<0.004wt%, all the other are Fe and inevitable impurity; Steel plate thickness after described hot rolling is 3 ~ 5mm.
Owing to adopting technique scheme, the present invention compared with prior art has following positively effect:
The present invention is based on cheap C, Si and Mn element, does not need to add the expensive alloying elements such as Nb, Ti, Ni and B, only adds a small amount of Mo element, with low cost; The a small amount of Mo added in soft steel significantly can promote bainitic transformation in the hot rolling, ensure that the cold rolled annealed front granular bainite being organized as fine uniform; Annealing completes in vacuum furnace, and technique is simple and with short production cycle; The cold rolling intensity of prepared low molybdenum high-strength steel that makes of large pressure significantly improves, die break refinement; The control of rational annealing temperature and annealing time, reduce few situation downward-extension rate in intensity and be improved significantly, intensity is mated well with plasticity.Prepared low molybdenum high-strength steel is after testing: yield strength is 800 ~ 950MPa; Tensile strength is 980 ~ 1200MPa; Unit elongation is 15 ~ 27%.
Therefore, the present invention has low production cost, technique feature simple and with short production cycle, and the intensity of prepared low molybdenum high-strength steel is mated with plasticity well, can meet the fields such as automobile, building and the energy to the requirement of structured material.
Accompanying drawing explanation
The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 1 prepared by the embodiment of the present invention 1;
The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 2 prepared by the embodiment of the present invention 2;
The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 3 prepared by the embodiment of the present invention 3;
The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 4 prepared by the embodiment of the present invention 4.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described, not limiting the scope of the invention.
embodiment 1
A kind of low molybdenum high-strength steel and preparation method thereof.Described preparation method is: to the steel plate acid-washing process after hot rolling, then adopts cold mill complex to the steel plate after pickling by 4 ~ 5 passes, is rolling to 0.8 ~ 1.0mm, obtains cold-rolled steel strip; Cold-rolled steel strip is heated to 570 ~ 620 DEG C with the rate of heating of 20 ~ 30 DEG C/s in vacuum furnace, and insulation 20 ~ 30min, is then cooled to 200 ~ 230 DEG C with the speed of cooling of 5 ~ 10 DEG C/s, cools to room temperature with the furnace.
Steel plate chemical composition after described hot rolling and content thereof are: C is 0.18 ~ 0.19wt%, Mn is 2.20 ~ 2.40wt%, Si is 1.20 ~ 1.30wt%, Mo is 0.08 ~ 0.10wt%, P<0.01wt%, S<0.003wt%, N<0.004wt%, all the other are Fe and inevitable impurity; Steel plate thickness after described hot rolling is 3 ~ 5mm.
Low molybdenum high-strength steel prepared by the present embodiment is after testing: yield strength is 910 ~ 950MPa; Tensile strength is 1153 ~ 1200MPa; Unit elongation is 15.0 ~ 17.1%.
embodiment 2
A kind of low molybdenum high-strength steel and preparation method thereof.Described preparation method is: to the steel plate acid-washing process after hot rolling, then adopts cold mill complex to the steel plate after pickling by 5 ~ 6 passes, is rolling to 1.0 ~ 1.2mm, obtains cold-rolled steel strip; Cold-rolled steel strip is heated to 570 ~ 620 DEG C with the rate of heating of 20 ~ 30 DEG C/s in vacuum furnace, and insulation 30 ~ 40min, is then cooled to 200 ~ 230 DEG C with the speed of cooling of 5 ~ 10 DEG C/s, cools to room temperature with the furnace.
Steel plate chemical composition after described hot rolling and content thereof are: C is 0.19 ~ 0.20wt%, Mn is 2.30 ~ 2.50wt%, Si is 1.30 ~ 1.40wt%, Mo is 0.10 ~ 0.12wt%, P<0.01wt%, S<0.003wt%, N<0.004wt%, all the other are Fe and inevitable impurity; Steel plate thickness after described hot rolling is 3 ~ 5mm.
Low molybdenum high-strength steel prepared by the present embodiment is after testing: yield strength is 891 ~ 930MPa; Tensile strength is 1137 ~ 1169MPa; Unit elongation is 16.8 ~ 18.9%.
embodiment 3
A kind of low molybdenum high-strength steel and preparation method thereof.Described preparation method is: to the steel plate acid-washing process after hot rolling, then adopts cold mill complex to the steel plate after pickling by 4 ~ 5 passes, is rolling to 0.9 ~ 1.1mm, obtains cold-rolled steel strip; Cold-rolled steel strip is heated to 620 ~ 670 DEG C with the rate of heating of 20 ~ 30 DEG C/s in vacuum furnace, and insulation 20 ~ 30min, is then cooled to 200 ~ 230 DEG C with the speed of cooling of 5 ~ 10 DEG C/s, cools to room temperature with the furnace.
Steel plate chemical composition after described hot rolling and content thereof are: C is 0.18 ~ 0.19wt%, Mn is 2.20 ~ 2.40wt%, Si is 1.20 ~ 1.30wt%, Mo is 0.08 ~ 0.10wt%, P<0.01wt%, S<0.003wt%, N<0.004wt%, all the other are Fe and inevitable impurity; Steel plate thickness after described hot rolling is 3 ~ 5mm.
Low molybdenum high-strength steel prepared by the present embodiment is after testing: yield strength is 820 ~ 870MPa; Tensile strength is 1002 ~ 1050MPa; Unit elongation is 21.2 ~ 25.3%.
embodiment 4
A kind of low molybdenum high-strength steel and preparation method thereof.Described preparation method is: to the steel plate acid-washing process after hot rolling, then adopts cold mill complex to the steel plate after pickling by 5 ~ 6 passes, is rolling to 0.9 ~ 1.2mm, obtains cold-rolled steel strip; Cold-rolled steel strip is heated to 620 ~ 670 DEG C with the rate of heating of 20 ~ 30 DEG C/s in vacuum furnace, and insulation 30 ~ 40min, is then cooled to 200 ~ 230 DEG C with the speed of cooling of 5 ~ 10 DEG C/s, cools to room temperature with the furnace.
Steel plate chemical composition after described hot rolling and content thereof are: C is 0.19 ~ 0.20wt%, Mn is 2.30 ~ 2.50wt%, Si is 1.30 ~ 1.40wt%, Mo is 0.10 ~ 0.12wt%, P<0.01wt%, S<0.003wt%, N<0.004wt%, all the other are Fe and inevitable impurity; Steel plate thickness after described hot rolling is 3 ~ 5mm.
Low molybdenum high-strength steel prepared by the present embodiment is after testing: yield strength is 800 ~ 850MPa; Tensile strength is 983 ~ 1020MPa; Unit elongation is 22.1 ~ 27.0%.
This embodiment, based on cheap C, Si and Mn element, does not need to add the expensive alloying elements such as Nb, Ti, Ni and B, only adds a small amount of Mo element, with low cost; The a small amount of Mo added in soft steel significantly can promote bainitic transformation in the hot rolling, ensure that the cold rolled annealed front granular bainite being organized as fine uniform; Annealing completes in vacuum furnace, and technique is simple and with short production cycle.
This concrete tissue implementing the low molybdenum high-strength steel of preparation is bainite+a small amount of martensite of fine uniform, as shown in Figure 1 to 4, the scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 1 prepared by the embodiment of the present invention 1, annealing temperature is 570 ~ 620 DEG C, and annealing time is 20 ~ 30min; The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 2 prepared by the embodiment of the present invention 2, annealing temperature is 570 ~ 620 DEG C, and annealing time is 30 ~ 40min; The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 3 prepared by the embodiment of the present invention 3, annealing temperature is 620 ~ 670 DEG C, and annealing time is 20 ~ 30min; The scanning lens figure of a kind of low molybdenum high-strength steel of Fig. 4 prepared by inventive embodiments 4, annealing temperature is 620 ~ 670 DEG C, and annealing time is 30 ~ 40min.
As can be seen from Fig. 1 ~ Fig. 4, cold rolled annealed rear uniform small grains, intensity and the toughness of prepared low molybdenum high-strength steel are obviously improved.Cold rolling due to what depress greatly, the segregation line occurred in crystal grain, has laid in a large amount of free energys, can as the forming core core of recrystal grain in recrystallization annealing process.And molybdenum element significantly can hinder the recrystallization process of Deformation structure, therefore can refinement recrystal grain.On the other hand, the rising of recrystallization annealing temperature can promote growing up of recrystal grain.Therefore, when annealing temperature is 570 ~ 620 DEG C, the degree that recrystallize carries out is lower, and changes in microstructure is little, still presents the state that cold rolling rear crystal grain is elongated, flattens, and intensity and plasticity change little; When annealing temperature reaches 620 ~ 670 DEG C, Deformation structure starts extensive recrystallize, occurs equi-axed crystal tiny in a large number in tissue, due to the Grain Refinement Effect of molybdenum, the intensity of prepared low molybdenum high-strength steel and plasticity all be improved significantly.Equally along with the prolongation of annealing time, intensity and plasticity also change to some extent, but relative to annealing temperature, the impact of annealing time is little.
The cold rolling intensity of prepared low molybdenum high-strength steel that makes of large pressure significantly improves, die break refinement; The control of rational annealing temperature and annealing time, reduce few situation downward-extension rate in intensity and be improved significantly, intensity is mated well with plasticity.Low molybdenum high-strength steel prepared by this embodiment is after testing: yield strength is 800 ~ 950MPa; Tensile strength is 980 ~ 1200MPa; Unit elongation is 15 ~ 27%.
Therefore, this embodiment has low production cost, technique feature simple and with short production cycle, and prepared low molybdenum steel intensity is mated with plasticity well, can meet the fields such as automobile, building and the energy to the requirement of structured material.
Claims (2)
1. a preparation method for low molybdenum high-strength steel, is characterized in that, to the steel plate acid-washing process after hot rolling, then adopts cold mill complex to the steel plate after pickling by 4 ~ 6 passes, is rolling to 0.8 ~ 1.2mm, obtains cold-rolled steel strip; Cold-rolled steel strip is heated to 570 ~ 670 DEG C with the rate of heating of 20 ~ 30 DEG C/s in vacuum furnace, and insulation 20 ~ 40min, is then cooled to 200 ~ 230 DEG C with the speed of cooling of 5 ~ 10 DEG C/s, cools to room temperature with the furnace;
Steel plate chemical composition after described hot rolling and content thereof are: C is 0.18 ~ 0.20wt%, Mn is 2.20 ~ 2.50wt%, Si is 1.20 ~ 1.40wt%, Mo is 0.08 ~ 0.12wt%, P<0.01wt%, S<0.003wt%, N<0.004wt%, all the other are Fe and inevitable impurity; Steel plate thickness after described hot rolling is 3 ~ 5mm.
2. a low molybdenum high-strength steel, is characterized in that described low molybdenum high-strength steel is the low molybdenum high-strength steel manufactured by the preparation method of low molybdenum high-strength steel according to claim 1.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105296852A (en) * | 2015-11-24 | 2016-02-03 | 西安三维应力工程技术有限公司 | Welding steel pipe for automobile transmission shaft and manufacturing method of welding steel pipe |
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| JP2000080439A (en) * | 1998-09-03 | 2000-03-21 | Nippon Steel Corp | Thin steel sheet for working |
| US20050150580A1 (en) * | 2004-01-09 | 2005-07-14 | Kabushiki Kaisha Kobe Seiko Sho(Kobe Steel, Ltd.) | Ultra-high strength steel sheet having excellent hydrogen embrittlement resistance, and method for manufacturing the same |
| JP2008080439A (en) * | 2006-09-27 | 2008-04-10 | Ishizuka Glass Co Ltd | Apparatus for machining and holding polyhedron, and machining method |
| CN102952996A (en) * | 2013-01-04 | 2013-03-06 | 鞍钢股份有限公司 | High-elongation cold-rolled TRIP (Transformation-Induced Plasticity) steel plate and preparation method thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000080439A (en) * | 1998-09-03 | 2000-03-21 | Nippon Steel Corp | Thin steel sheet for working |
| US20050150580A1 (en) * | 2004-01-09 | 2005-07-14 | Kabushiki Kaisha Kobe Seiko Sho(Kobe Steel, Ltd.) | Ultra-high strength steel sheet having excellent hydrogen embrittlement resistance, and method for manufacturing the same |
| JP2008080439A (en) * | 2006-09-27 | 2008-04-10 | Ishizuka Glass Co Ltd | Apparatus for machining and holding polyhedron, and machining method |
| CN102952996A (en) * | 2013-01-04 | 2013-03-06 | 鞍钢股份有限公司 | High-elongation cold-rolled TRIP (Transformation-Induced Plasticity) steel plate and preparation method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105296852A (en) * | 2015-11-24 | 2016-02-03 | 西安三维应力工程技术有限公司 | Welding steel pipe for automobile transmission shaft and manufacturing method of welding steel pipe |
| CN105296852B (en) * | 2015-11-24 | 2017-03-29 | 西安三维应力工程技术有限公司 | Welded still pipe used for vehicle transmission shaft and its manufacture method |
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