CN103667893B - The high-strength steel with anti-delayed fracture of yield tensile ratio≤0.5 and production method - Google Patents
The high-strength steel with anti-delayed fracture of yield tensile ratio≤0.5 and production method Download PDFInfo
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- CN103667893B CN103667893B CN201310649762.XA CN201310649762A CN103667893B CN 103667893 B CN103667893 B CN 103667893B CN 201310649762 A CN201310649762 A CN 201310649762A CN 103667893 B CN103667893 B CN 103667893B
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Abstract
The high-strength steel with anti-delayed fracture of yield tensile ratio≤0.5, its component and wt% are: C:0.11 ~ 0.25%, Mn:15.5 ~ 17.5%, Mo:0.030 ~ 0.050%, Co:0.005 ~ 0.02%, B:0.005 ~ 0.009%, N:0.009 ~ 0.011%, La+Ce+Nd:0.011 ~ 0.025%; Production stage: desulfurizing iron; Converter smelting; RH vacuum-treat; Continuous casting; Hot rolling, finishing temperature is at 755 ~ 790 DEG C; Cold rolling, its draft is 51 ~ 54%; Continuous annealing.The invention solves the problem that existing same level high-strength steel unit elongation is low, yield tensile ratio is high and welding property is bad, avoid delayed fracture phenomenon and occur; Its automobile collision preventing parts manufactured are better than the plasticity of other cold rolling high-strength steel, welding property and energy absorption, considerably increase safety in utilization and the loss of weight energy saving of product; Have employed B, Mo, Co, N, realize refined crystalline strengthening and precipitation strength, ensure that low yield strength ratio and thermotolerance, erosion resistance; Steel plate also has double effect and low yield strength ratio, ensure that the formed machining ability that material is good and load and resistance to fracture.
Description
Technical field
The present invention relates to a kind of cold rolling high-strength steel and production method thereof, belong to a kind of high-strength steel with anti-delayed fracture and production method of yield tensile ratio≤0.5 particularly.
Background technology
Automobile is car Lightweight Technology development especially, the steel such as its crashproof parts and important crossbeam longeron wheel cover floor require to have high strength and high-ductility, and there is good plasticity and good weldability, martensitic steel is while guarantee high strength, its forming property does not reach requirement, its carbon equivalent significantly improves, and weldability is difficult to meet the demands.
Through retrieval, Chinese Patent Application No. is the document of CN201210012636.9, and disclosing a kind of low cost large expansion-ratio expansion pipe TWIP steel and steel pipe preparation method, though its performance reaches requirement, belong to hot-rolled steel sheet, is for pipe line steel.And the automobile especially multiplex cold rolling or galvanizing production of vehicle structural part, thickness is at 0.6 ~ 2.0mm, hot-rolled steel cannot reach this thickness requirement, and it has single TWIP effect, cost can significantly increase, and its single austenite certainly will need Fe content could realize more than 20, and need containing very high carbon content and high content of silicon and aluminum simultaneously.Like this, bring great difficulty to smelting, Fe content is too high-leveled and difficult to be produced to realize converter steelmaking, and meanwhile, mold gap can be caused to block for high silicon or high alumina and strand can crack.
The present invention is for addressing these problems, adopt special Composition Design and production technique, finished product belongs to cold rolled annealed steel or carries out zinc-plated on cold rolling material basis, realize the high-strength steel with the excellent combination property of TRIP/TWIP double effect, there is delayed fracture resistance, meet the manufacture requirements of automobile especially vehicle structural part, crashproof parts, also can be used for pipeline, boats and ships, engineering machinery, war products.
Summary of the invention
The present invention is directed to the deficiency of the existence of prior art; meet the demand of the situations such as environment protection, the energy, safety; there is provided a kind of loss of weight energy-conservation; yield strength is not less than 800MPa, unit elongation >=58% in 350 ~ 400MPa, tensile strength; strain-hardening index >=0.460, and the high-strength steel with anti-delayed fracture and the production method with yield tensile ratio≤0.5 of good delayed fracture resistance, good fatigue property and good low temperature resistant fragility.
Realize the measure of above-mentioned purpose:
The high-strength steel with anti-delayed fracture of yield tensile ratio≤0.5, its component and weight percent content are: C:0.11 ~ 0.25%, Mn:15.5 ~ 17.5%, Mo:0.030 ~ 0.050%, Co:0.005 ~ 0.02%, B:0.005 ~ 0.009%, N:0.009 ~ 0.011%, La+Ce+Nd:0.011 ~ 0.025%, surplus is Fe and inevitable impurity; Its yield strength is at 350 ~ 400MPa, more than tensile strength 800MPa, unit elongation >=58%, yield tensile ratio≤0.5, strain-hardening index >=0.460, heterogeneous microstructure is: austenite and twins sub-structure or austenite+martensite or austenite+martensite base core.
The method with the high-strength steel of anti-delayed fracture of production yield tensile ratio≤0.5, its step:
(1) desulfurizing iron: control departures S≤0.005%;
(2) converter smelting: basicity of slag 2.5 ~ 4.5; Time 1 ~ 3min is stirred after converter smelting; Converter terminal employing is high draws technique of re-blowing, and re-blows and is no more than 2 times; The tapping time: 3 ~ 10min; Component controlling carries out in ladle: tap to 1/3 time, add alloying element; Converter tapping adopts Si, Ca, Al complex deoxidization, and Si adds according to 0.7 ~ 1.3 kg/tonne of steel, and Ca adds according to 1.6 ~ 2.4 kgs/tonne of steel, and Al adds according to 0.3 ~ 0.7 kg/tonne of steel; Top and bottom combined blown converter furnace bottom adopts gas permeable brick to be 6 pieces, and every block gas permeable brick air flow is no more than 120m
3/ h; Blow intensity again and be not less than 0.040m3/min. ton steel, dissolved oxygen is 0.005 ~ 0.006%; And enter Zhong Bao, control its superheating temperature at 15 ~ 25 DEG C;
(3) carry out vacuum-treat at RH vacuum oven: vacuum tightness≤100Pa, vacuum processing time is not less than 15min, molten steel H≤1.5ppm;
(4) continuous casting is carried out: crystallization control device liquid level, at 80 ± 3mm, controls the water distribution of continuous caster second cooling section at 0.6 ~ 0.85 liter of/kilogram of steel;
(5) heat strand, heating and temperature control is at 1130 ~ 1150 DEG C;
(6) carry out hot rolling, control finishing temperature at 755 ~ 790 DEG C;
(7) carry out cold rolling, draft controls 51 ~ 54%;
(8) continuous annealing temperature is not less than 800 DEG C; Cool with the speed of cooling being not less than 40 DEG C/s.
It is characterized in that: when the cold-reduced sheet produced carries out pot galvanize, control pot galvanize annealing section temperature and be not less than 800 DEG C, dew point controls at-42 ~-45 DEG C, and band steel enters zinc pot temperature at 483 ~ 495 DEG C, controls zinc liquid temperature and is not less than 460 DEG C.
The effect of each element in the present invention
C element can stable austenite tissue, and solid solution hardening can be utilized to strengthen matrix.The solid solubility of C in austenite, than much higher in ferrite, for this reason, present invention employs certain C content.C content is too low, and intensity is difficult to ensure; C content is too high, and plasticity and impact fatigue behavior can reduce, and for this reason, C content of the present invention controls in 0.11 ~ 0.25% scope.
Mn content can keep steel plate to be organized as austenite, and the mechanical property of austenitic steel depends primarily on stacking fault energy, and under given texturizing condition, stacking fault energy only depends on chemical composition.Stacking fault energy decides main deformation mechanism type, as the martensitic transformation that the slippage of slippage, commutative Banach aglebra, partial dislocation, twinning deformation or strain cause.Generally first slippage occurs during deformation, when slippage is interrupted, metal plastic deformation drag is increased, and stress concentration reaches twin critical shear stress, occurs twin.When there occurs twinning deformation under the effect of crystal in shearing stress, a part for crystal does uniform shear along certain twinning plane and twin direction relative to another part crystal, the lattice type of crystal does not change, but it makes the crystalline orientation in homogeneous shear district change, become and become mirror symmetry orientation with non-slipped region crystal.Vital effect is served in the later stage twin crystal inducing plasticity effect of distortion, material of the present invention is obtained while high strength there is high-ductility, a small amount of unstable austenite occurs in parts machining process to martensitic transformation or change civilian martensite base core ε phase.Mn content is too low, is difficult to ensure austenitic structure, is also just difficult to ensure high-ductility; Mn too high levels increases material cost and production difficulty increases, and meanwhile, easily form banded structure, for this reason, Mn content of the present invention controls in 15.5% ~ 17.5% scope.
Mo significantly improves intensity, simultaneously can crystal grain thinning.Content too low being difficult to reaches Grain refinement, and too high levels can improve yield tensile ratio, increases cost simultaneously.For this reason, Mo content of the present invention controls in 0.030 ~ 0.050% scope.
Co significantly increases thermotolerance and the erosion resistance of steel, and content is low, and effect is difficult to meet, and content height increases cost.For this reason, Co content of the present invention controls in 0.005 ~ 0.02% scope.
B can make yield strength reduce and tensile strength improves, and finally reduces yield tensile ratio.The low DeGrain of content, content is high, raises the cost and production difficulty.For this reason, B content of the present invention controls in 0.005 ~ 0.009% scope.
N can impel microalloy element to fix and under suitable production technique, reach precipitation strength.Too low, be difficult to the size and the distribution density that meet precipitate, Tai Gaoyi brings the unfavorable phenomenons such as crackle to occur.For this reason, N content of the present invention controls in 0.009 ~ 0.011% scope.
La+Ce+Nd: can play anti-delayed fracture effect, content is too low, is difficult to ensure anti-delayed fracture, and difficulty and production cost are smelted in too high increase.For this reason, La+Ce+Nd content controls in 0.011 ~ 0.025% scope by the present invention.
The invention solves existing same level high-strength steel as dual phase steel and TRIP steel unit elongation is low, yield tensile ratio is high and welding property is bad problem, and avoid delayed fracture phenomenon and occur.Steel plate has low yield strength ratio, high elongation, high strain-hardening index and good spot weldability, the automobile collision preventing parts of material manufacture of the present invention are better than the plasticity of other cold rolling high-strength steel, intensity, welding property and good energy absorption, considerably increase safety in utilization and the loss of weight energy saving of manufactured product; And on composition, adopt B, Mo, Co, N micro alloying element, realize refined crystalline strengthening and precipitation strength, ensure that low yield strength ratio and thermotolerance, erosion resistance simultaneously; Because steel plate also has double effect and low yield strength ratio, ensure that the formed machining ability that material is good and load and resistance to fracture; While guarantee basic mechanical performance, there is good weldability.
Accompanying drawing explanation
Accompanying drawing is metallographic structure figure of the present invention.
Embodiment
Below the present invention is described in detail:
Table 1 is the value list of various embodiments of the present invention and comparative example;
Table 2 is the main technologic parameters list of various embodiments of the present invention and comparative example;
Table 3 is various embodiments of the present invention and the list of comparative example Performance Detection situation.
Various embodiments of the present invention are produced according to following steps:
(1) desulfurizing iron: control departures S≤0.005%;
(2) converter smelting: basicity of slag 2.5 ~ 4.5; Time 1 ~ 3min is stirred after converter smelting; Converter terminal employing is conventional high draws technique of re-blowing, and re-blows and is no more than 2 times; The tapping time: 3 ~ 10min; Component controlling carries out in ladle: tap to 1/3 time, add alloying element; Converter tapping adopts Si, Ca, Al complex deoxidization, and Si adds according to 0.7 ~ 1.3 kg/tonne of steel, and Ca adds according to 1.6 ~ 2.4 kgs/tonne of steel, and Al adds according to 0.3 ~ 0.7 kg/tonne of steel; Top and bottom combined blown converter furnace bottom adopts gas permeable brick to be 6 pieces, and every block gas permeable brick air flow is no more than 120m
3/ h; Blow intensity again and be not less than 0.040m3/min. ton steel, dissolved oxygen is 0.005 ~ 0.006%; And enter Zhong Bao, control its superheating temperature at 15 ~ 25 DEG C;
(3) carry out vacuum-treat at RH vacuum oven: vacuum tightness≤100Pa, vacuum processing time is not less than 15min, molten steel H≤1.5ppm;
(4) continuous casting is carried out: crystallization control device liquid level, at 80 ± 3mm, controls the water distribution of continuous caster second cooling section at 0.6 ~ 0.85 liter of/kilogram of steel;
(5) heat strand, heating and temperature control is at 1130 ~ 1150 DEG C;
(6) carry out hot rolling, control finishing temperature at 755 ~ 790 DEG C;
(7) carry out cold rolling, draft controls 51 ~ 54%;
(8) continuous annealing temperature is not less than 800 DEG C; Cool with the speed of cooling being not less than 40 DEG C/s.
It is characterized in that: when the cold-reduced sheet produced carries out pot galvanize, control pot galvanize annealing section temperature and be not less than 800 DEG C, dew point controls at-42 ~-45 DEG C, and band steel enters zinc pot temperature at 483 ~ 495 DEG C, controls zinc liquid temperature and is not less than 460 DEG C.
Table 1 various embodiments of the present invention and comparative example substrate chemical composition, wt%
Table 2 various embodiments of the present invention and the list of comparative example main technologic parameters value
Table 3 various embodiments of the present invention and the list of comparative example performance test results
Note: be processed into tension specimen, preliminary draft 2%, then under the physical environment of room temperature, exposing placement 200 days, there is not crackle and phenomenon of rupture in sample.
Above-described embodiment is only the best and exemplifies, and is not the restriction to embodiments of the present invention.
Claims (3)
1. the high-strength steel with anti-delayed fracture of yield tensile ratio≤0.5, its component and weight percent content are: C:0.11 ~ 0.25%, Mn:15.5 ~ 17.5%, Mo:0.030 ~ 0.050%, Co:0.005 ~ 0.02%, B:0.005 ~ 0.009%, N:0.009 ~ 0.011%, La+Ce+Nd:0.011 ~ 0.025%, surplus is Fe and inevitable impurity; Its yield strength is at 350 ~ 400MPa, tensile strength 800 ~ 910MPa, unit elongation 58 ~ 67%, yield tensile ratio 0.43 ~ 0.44, strain-hardening index 0.460 ~ 0.500, heterogeneous microstructure is: austenite and twins sub-structure or austenite+martensite or austenite+martensite base core.
2. produce the method with the high-strength steel of anti-delayed fracture of yield tensile ratio≤0.5 as claimed in claim 1, its step:
(1) desulfurizing iron: control departures S≤0.005%;
(2) converter smelting: basicity of slag 2.5 ~ 4.5; Time 1 ~ 3min is stirred after converter smelting; Converter terminal employing is conventional high draws technique of re-blowing, and re-blows and is no more than 2 times; The tapping time: 3 ~ 10min; Component controlling carries out in ladle: tap to 1/3 time, add alloying element; Converter tapping adopts Si, Ca, Al complex deoxidization, and Si adds according to 0.7 ~ 1.3 kg/tonne of steel, and Ca adds according to 1.6 ~ 2.4 kgs/tonne of steel, and Al adds according to 0.3 ~ 0.7 kg/tonne of steel; Top and bottom combined blown converter furnace bottom adopts gas permeable brick to be 6 pieces, and every block gas permeable brick air flow is no more than 120m
3/ h; Blow intensity again and be not less than 0.040m
3/ min ton steel, dissolved oxygen is 0.005 ~ 0.006%; And enter Zhong Bao, control its superheating temperature at 15 ~ 25 DEG C;
(3) carry out vacuum-treat at RH vacuum oven: vacuum tightness≤100Pa, vacuum processing time is not less than 15min, molten steel H≤1.5ppm;
(4) continuous casting is carried out: crystallization control device liquid level, at 80 ± 3mm, controls the water distribution of continuous caster second cooling section at 0.6 ~ 0.85 liter of/kilogram of steel;
(5) heat strand, heating and temperature control is at 1130 ~ 1150 DEG C;
(6) carry out hot rolling, control finishing temperature at 755 ~ 790 DEG C;
(7) carry out cold rolling, draft controls 51 ~ 54%;
(8) continuous annealing temperature is not less than 800 DEG C; Cool with the speed of cooling being not less than 40 DEG C/s.
3. the method with the high-strength steel of anti-delayed fracture of production yield tensile ratio≤0.5 as claimed in claim 2, it is characterized in that: when the cold-reduced sheet produced carries out pot galvanize, control pot galvanize annealing section temperature and be not less than 800 DEG C, dew point controls at-42 ~-45 DEG C, band steel enters zinc pot temperature at 483 ~ 495 DEG C, controls zinc liquid temperature and is not less than 460 DEG C.
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| CN106987790A (en) * | 2017-04-10 | 2017-07-28 | 唐山钢铁集团有限责任公司 | The continuous zinc coating method of high-silicon high-manganese galvanized steel strip |
| CN112276030B (en) * | 2020-10-13 | 2021-11-19 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength delayed fracture-resistant hot-rolled steel rail and preparation method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10306316A (en) * | 1997-04-28 | 1998-11-17 | Nippon Steel Corp | Production of low yield ratio high tensile-strength steel excellent in low temperature toughness |
| CN101921970A (en) * | 2009-04-27 | 2010-12-22 | 大同特殊钢株式会社 | High anti-corrosion, high strength and non-magnetic stainless steel, high anti-corrosion, high strength and non-magnetic stainless steel product and production method thereof |
| CN102365382A (en) * | 2009-03-10 | 2012-02-29 | 麦克思普朗克铁研究院有限公司 | Corrosion-resistant austenitic steel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH029294A (en) * | 1988-06-27 | 1990-01-12 | Nippon Telegr & Teleph Corp <Ntt> | Isdn subscriber radio communication system |
| KR101018131B1 (en) * | 2007-11-22 | 2011-02-25 | 주식회사 포스코 | High strength and low yield ratio steel for structure having excellent low temperature toughness |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10306316A (en) * | 1997-04-28 | 1998-11-17 | Nippon Steel Corp | Production of low yield ratio high tensile-strength steel excellent in low temperature toughness |
| CN102365382A (en) * | 2009-03-10 | 2012-02-29 | 麦克思普朗克铁研究院有限公司 | Corrosion-resistant austenitic steel |
| CN101921970A (en) * | 2009-04-27 | 2010-12-22 | 大同特殊钢株式会社 | High anti-corrosion, high strength and non-magnetic stainless steel, high anti-corrosion, high strength and non-magnetic stainless steel product and production method thereof |
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Effective date of registration: 20170711 Address after: 430083 Qingshan District, Hubei, Wuhan factory before the door No. 2 Patentee after: WUHAN IRON AND STEEL Co.,Ltd. Address before: 430080 Wuhan, Hubei Friendship Road, No. 999, Wuchang Patentee before: WUHAN IRON AND STEEL (GROUP) Corp. |
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