CN107723589B - A kind of middle carbon nanometer bainite ultrahigh-strength steel plates and preparation method thereof - Google Patents
A kind of middle carbon nanometer bainite ultrahigh-strength steel plates and preparation method thereof Download PDFInfo
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
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- C21D6/001—Heat treatment of ferrous alloys containing Ni
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- 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
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- 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
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- 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
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- 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
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- 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
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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Abstract
The present invention provides a kind of middle carbon nanometer bainite ultrahigh-strength steel plates and preparation method thereof, belong to metal material field, technical solution is a kind of middle carbon nanometer bainite ultrahigh-strength steel plates, chemical quality percentage is as follows: C:0.52 ~ 0.58%, Si:1.5 ~ 1.8%, Mn:1.6 ~ 2.0%, Mo:0.18 ~ 0.24%, Ni:1.2 ~ 1.7%, P: < 0.02%, S: < 0.02%, surplus is Fe and inevitable impurity, and the tensile strength of the steel plate is not less than 6.5% not less than 629HV1.0, breaking elongation not less than 2380MPa, hardness.The utility model has the advantages that strengthening with overcooling austenite rolling deformation, so that nanometer bainite structure starts transition temperature and transition temperature and reduces, crystal grain refinement, dislocation retains, and intensity is high, plasticity is good, good welding performance, and production efficiency improves, at low cost.
Description
Technical field
The present invention relates to metal material fields, and in particular to a kind of middle carbon nanometer bainite ultrahigh-strength steel plates and its preparation
Method.
Background technique
Nanometer bainite structure of steel has high-intensitive, higher fracture toughness and preferable compression plasticity, comprehensive performance excellent
Good, United States Patent (USP) US6884306 has invented a kind of Si-Mn-Cr-Ni-Mo-V nanometers of bainitic steel, C and Si content is higher in steel,
Respectively reach 0.6 ~ 1.1% and not less than 1.5%(weight percent), the prolonged homogenizing annealing of first high temperature after ingot casting slow cooling,
Overcooling austenite Isothermal Bainite is carried out in the low temperature of a little higher than steel Ms (martensite start) point after austenitizing again to turn
Become, obtains the nanometer bainite structure being made of the lath bainitic ferrite and retained austenite of nanometer grade thickness, but the party
Method fringe time is up to 1 ~ 3 week, low efficiency, long preparation period.
In order to accelerate Isothermal Bainite to change, shortens the production cycle, add in above-mentioned high-carbon Si-Mn-Cr-Ni-Mo-V steel
Add Co or Co+Al, the bainite transformation time can be made to greatly shorten, but Co price is high, cost of alloy greatly increases.Chinese invention is special
Sharp CN101693981A discloses a kind of preparation method of low-alloy high-carbon steel with high-strength and high ductility nano structure, i.e., in high-carbon steel
It adds Mn, Cr, Si, Al, W and carries out alloying, not adding Co reduces cost, and ingot casting carries out being rolled into slab and eliminates casting and lack
It falling into, hot rolling slab isothermal bainite transformation directly in salt bath has obtained nanometer bainite structure, and tensile strength is 2000 ~
2300MPa, breaking elongation are 6.7 ~ 7.8%.But the weldability and impact flexibility of this high-carbon nanometer bainitic steel are poor, significantly
Limit its application range as structural steel.In order to extend the application range of this nanometer bainite structure, researcher's examination
Figure in carbon content is lower, in low carbon and high silicon steel prepare nanometer bainite, but carbon content reduce, so that martensite transfor mation is started temperature
Degree increases, this temperature that Isothermal Bainite is changed improves, and degree of supercooling reduces, and lath of bainite thickness will increase, unfavorable
In obtaining nanometer bainite, further researcher inhibits to draw since carbon content reduces by adding more alloying element Ni
The Ms (martensite start) point risen increases, but which results in the gap mistakes between martensite and bainite start temperature
It is small, so that the temperature window of bainite transformation is almost disappeared, is also unfavorable for obtaining nanometer bainite structure.Applicant is in middle promulgated by the State Council
A kind of preparation side of nanostructure carbide-free bainite medium-carbon alloy steel is disclosed in bright patent ZL 201110255203.1
Method, this method deform to reduce Ms (martensite start) point and improve austenite intensity using overcooling austenite cold plasticity,
To allow deformed austenite in lower temperature isothermal transformation, austenite intensity raising in addition increases its shear drag, causes
The lath of bainite thickness for obtaining isothermal transformation significantly reduces, and a nanometer bainite structure is so obtained in medium carbon steel.
But in the chemical component for being suitable for preparing nanometer bainitic steel of the patent disclosure, containing a large amount of alloying element, cost of alloy is too
Height, moreover, the preparation of this nanometer bainitic steel is completed on thermomechanical simulation test machine, prepared nanometer bainite
Steel curved beam size is too small, using being also extremely restricted.The Chinese invention patent of application number 03150091.9, disclose with C,
Mn, Si be main alloy element middle carbon and medium high carbon manganese systems air-cooled bainitic steels, it is air-cooled tissue be carbide-free Bainite and
The heterogeneous structure of martensite, the tensile strength after lonneal are 1900MPa, elongation percentage 7%, and intensity is far below high-carbon nanometer
Bainitic steel, and the martensite in this heterogeneous structure can reduce plasticity and toughness.Application No. is 201610461170.9 middle promulgateds by the State Council
Bright patent discloses the high strength and ductility nanostructure bainitic steel for body of a motor car anticollision component, C content percentage by weight
Than being 0.55 ~ 0.65, belong to medium carbon steel, preparation step is related to three step isothermal transformation, accumulate total isothermal transformation time up to 34 ~
120h, and the tensile strength of prepared nanostructure bainitic steel is only 1421 ~ 1771MPa, elongation percentage is 10.7 ~
11.4%, the production cycle is long, and product strength is far below high-carbon nanometer bainitic steel.The China of application number 201310423172.5
Patent of invention discloses a kind of 2100MPa nanometers of bainitic steel and preparation method thereof, which contains a large amount of Co and Al, at high cost
And there are continuous casting sprues to block risk, tensile strength is up to 2070MPa in the embodiment provided, and elongation percentage only has 6%, and waits
Warm fringe time is up to 96h.The Chinese invention patent of application number 201410135887.5, disclose a kind of 2400MPa grades it is low
The preparation method of cost nanometer bainitic steel, the steel are C-Si-Mn-Al system, and chemical component is by weight percentage are as follows: C 0.50 ~
1.00, Si 2.00 ~ 3.00, Mn 0.30 ~ 0.50, Al 0.50 ~ 1.00, isothermal transformation obtain a nanometer bainite structure, embodiment
In as it can be seen that the carbon content of steel is respectively 0.6,0.8 and 0.9 by weight percentage, tensile strength and prolong after 230 DEG C of isothermal transformation
The rate of stretching is respectively 2390MPa, 2399MPa, 2339MPa and 7.0%, 3.1%, 1.3%；And the tensile strength after 300 DEG C of isothermal transformation
1803MPa, 1975MPa, 1955MPa and 11.3%, 12.5%, 15.6% are distinguished with elongation percentage.The nanometer bainite of this method preparation
Elongation percentage is lower when hardness of steel is close to 2400MPa, and wherein to easily lead to continuous casting sprue during the preparation process stifled by the higher Al of content
Plug, the high Si of content easily cause brittleness to increase and be unfavorable for welding.In summary it finds, at present carbon nanometer bainitic steel in acquisition
The method of tissue, there are many difficult points, such as the production cycle is long, at high cost, plasticity is poor, brittleness is big, and obtained structure of steel is comprehensive
Performance is bad, and application is significantly limited.
Summary of the invention
To solve, the existing middle carbon nanometer bainite structure of steel production cycle is long, at high cost, plasticity is poor, brittleness is big, comprehensive
Can difference technical problem, the present invention provides a kind of middle carbon nanometer bainite ultrahigh-strength steel plates and preparation method thereof, passes through science
Accurate optimization structure of steel chemical constituent, the accurate ingot casting that controls carry out consumable, homogenizing annealing and hot rolling, further spheroidizing
Afterwards, then heat preservation and salt bath cooling are reheated, is strengthened using overcooling austenite rolling deformation, reduced martensite and start transformation temperature
Degree, and accelerate bainite transformation, it shortens the production cycle to realize, reduce alloying element cost, obtained middle carbon is received
Rice structure bainite ultrahigh-strength steel plates quality stability height, intensity and hardness greatly improve, plasticity is good.
The technical solution adopted by the present invention is that:
A kind of middle carbon nanometer bainite ultrahigh-strength steel plates, the steel plate chemical quality percentage are as follows: C:0.52 ~
0.58%, Si:1.5 ~ 1.8%, Mn:1.6 ~ 2.0%, Mo:0.18 ~ 0.24%, Ni:1.2 ~ 1.7%, P: < 0.02%, S: < 0.02%, it is remaining
Amount is Fe and inevitable impurity, and the tensile strength of the steel plate is not less than 2380 MPa, hardness is not less than 629HV1.0, total
Elongation percentage is not less than 6.5%.
The present invention also provides a kind of preparation method of middle carbon nanometer bainite ultrahigh-strength steel plates, the chemical matter of the steel plate
It is as follows to measure percentage: C:0.52 ~ 0.58%, Si:1.5 ~ 1.8%, Mn:1.6 ~ 2.0%, Mo:0.18 ~ 0.24%, Ni:1.2 ~ 1.7%,
P: < 0.02%, S: < 0.02%, surplus is Fe and inevitable impurity；
The preparation method comprises the following steps:
(1) it melting: fed intake according to above-mentioned chemical component, melting and pour into ingot casting；
(2) consumable: carrying out vacuum consumable remelting for ingot casting, derives from consumption ingot；
(3) homogenizing annealing, hot rolling: consumable ingot is heated to 1150 ~ 1250 DEG C of heat preservation 50-70min homogenizing annealings, so
It hot rolling and is cooled to room temperature afterwards, obtains hot rolling bar stock；
(4) spheroidizing: after hot rolling bar stock is heated to 680 ~ 750 DEG C of heat preservation 13-17 h, slow cooling to room temperature must anneal
Bar stock；
(5) ausrolling deforms: annealing bar stock being reheated to 880 ~ 930 DEG C of heat preservation 15-30 min, is transferred to rapidly
It is cooling in 500-580 DEG C of salt bath furnace, it is taken out after samming and carries out one-pass roller rapidly into plate；It is transferred to 190 ~ 240 DEG C immediately again
Salt bath furnace in 13-20 h carry out isothermal processes, come out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite ultrahigh-strength steel plates.
Further, controlling hot rolling finishing temperature rolls rear slow cooling to room temperature at 850 ~ 930 DEG C in the step (3).
Further, slow cooling to room temperature is first furnace cooling to 400-450 DEG C in the step (4), then comes out of the stove and be air-cooled to
Room temperature.
Further, temperature is controlled at 200-220 DEG C in salt bath furnace in step (5) Isothermal Treatment Process.
Further, roll control total deformation 30 ~ 40% in the step (5).
Further, step (5) salt bath furnace is controlled at 220 ~ 240 DEG C.
Further, 2380 MPa or more of tensile strength of carbon nano-structured bainite ultrahigh-strength steel plates in described, hard
Spend 629HV1.0 or more, 6.5% or more breaking elongation.
In the chemical constituent of middle carbon nanometer bainite ultrahigh-strength steel plates, C(carbon) it is most effective solution strengthening member in steel
Element can greatly improve harden ability, reduce the martensite start temperature of steel, but its too high levels will lead to steel weldability and tough
Property be deteriorated, it is too low that hardness of steel is caused to reduce；Si(silicon) precipitation of carbide in isothermal transformation can be hindered, general content is answered
Higher than 1.5wt.%, but it is excessively high, cause toughness to reduce；Mn(manganese) it is to expand austenite phase p-block element p, harden ability can be improved, reduce
Martensite start temperature reduces bainite transformation temperature, refines bainite ferrite lath, and excessively high Mn content easily causes
Banded structure, and slow down bainite transformation, the production cycle is long；Mo(molybdenum) perlitic transformation and Carbide Precipitation can be postponed, carefully
Change austenite grain, reduce temper brittleness tendency, but price is higher, therefore the control of its content is in 0.18 ~ 0.24wt.%；Ni(nickel) it can
Expand austenite phase field, reduce the martensite start temperature of steel, improve harden ability, guarantees that overcooling austenite is with higher
Stability improves toughness；P(phosphorus) and S(sulphur) it is harmful element, control as far as possible lower, but de- P, S smelting cost is higher, therefore,
Cost need to be taken into account and guarantee properties of product.Above-mentioned technical proposal is matched by scientific optimization chemical constituent, is mentioned for steel product performance
Basic guarantee has been supplied, martensite start temperature is effectively reduced, has improved intensity, toughness, has improved quality stability, has been guaranteed
Structure of steel comprehensive performance excellent simultaneously takes into account cost, selects C content range 0.52 ~ 0.58%, Si content range 1.5 ~ 1.8%, Mn
Content range 1.6 ~ 2.0%, Mo content range 0.18 ~ 0.24%, Ni content range 1.2 ~ 1.7%, control P, S content are lower than
0.02wt.%, compared with high-carbon nanometer bainitic steel, C content is reduced the proportion, and weldability can greatly improve, and be not necessarily to
Addition cobalt and aluminium element, cost of alloy substantially reduce, while also avoiding nozzle blocking caused by aluminium when continuous casting in preparation process.
On the basis of optimizing component, preparation method has been advanced optimized, feed intake according to above-mentioned chemical component progress routine,
Melting and after pouring into ingot casting, carries out vacuum consumable remelting to remove impurity, derives from consumption ingot.Then consumable ingot is heated to
1150 ~ 1250 DEG C of heat preservation 50-70min homogenizing annealings more preferable 1200 ~ 1220 DEG C of temperature, are somebody's turn to do so that ingot casting homogenization of composition
On the one hand higher temperature range makes the chemical component of steel and microstructure homogenization degree high, shorten the time, energy consumption it is overall compared with
It is low；On the other hand, excessively growing up for crystal grain is avoided, refining grain size is suitable, provides for the uniform and stable property of plate property
Good condition.It hot rolling and is cooled to room temperature after homogenizing annealing, to remove casting flaw；It is then heated to 680 ~ 750 DEG C, it is excellent
680-700 DEG C is selected, 13-17 h is kept the temperature, then slow cooling carries out spheroidizing, make carbide spheroidization, be subsequent hot-working to room temperature
Tissue preparation is done with heat treatment.Finally carry out ausrolling deformation and isothermal processes, i.e., further it is reheated to 880 ~
930 DEG C of heat preservation 15-30 min are transferred to rapidly in 500 ~ 580 DEG C of salt bath furnaces cooling, the rapid progress list of taking-up after 3-10min samming
Passes at plate, then be transferred to 190 ~ 240 DEG C immediately, 13-20 h is carried out at isothermal in preferably 200 ~ 220 DEG C of salt bath furnace
Reason, comes out of the stove and is air-cooled to room temperature, obtain middle carbon nanometer bainite ultrahigh-strength steel plates.Austria is subcooled in breakthrough ingenious utilize of the above method
Family name's body rolling deformation leads to Austenite strengthening, to reduce martensite start temperature, and then realizes isothermal shellfish at low temperature
The transformation of family name's body, and accelerate bainite transformation；Isothermal processes select 190 ~ 240 DEG C, preferably 200 ~ 220 DEG C, under the low temperature range
Isothermal Bainite transformation reduces bainite ferrite lath thickness, obtains nanoscale bainite structure, improves intensity, and roll
System deformation overcooling austenite increases dislocation density, and a large amount of dislocations are hereditary to bainite ferrite, further improves intensity,
Finally obtain middle carbon nanometer bainite ultrahigh-strength steel plates.Carbon nanometer bainite steel plate microstructure is by average thickness in gained
(percent by volume is 70% ~ 90% to the lath bainitic ferrite of 70-120nm, more preferable 77% ~ 88%) and retained austenite (body
Product percentage is 10% ~ 30%, more preferable 12% ~ 23%) composition, tensile strength up to 2380 MPa or more, hardness up to 629HV1.0 with
Upper, breaking elongation is higher than 6.5%, these mechanical performance indexs have reached the level of high-carbon nanometer bainitic steel, and welding performance etc.
It is significantly better than high-carbon nanometer bainitic steel.The above process also utilizes austenite deformation to accelerate bainite transformation simultaneously, shortens at heat
The period is managed, technique, production efficiency is improved, also reduces production cost.
Beneficial effects of the present invention: (1) a kind of middle carbon nanometer bainite ultrahigh-strength steel plates of the invention, chemical component section
Proportion is learned, the accurate preparation method of cooperation science is ingenious to strengthen with overcooling austenite rolling deformation, so that nanometer bainite group
It knits and starts transition temperature and transition temperature and reduce, crystal grain refinement, dislocation retains, and tensile strength is up to 2380 MPa or more, hardness
Up to 629HV1.0 or more, 6.5% or more breaking elongation, there is high-intensitive, high-ductility, the good excellent combination mechanics of welding performance
Performance, and it is at low cost；(2) preparation method of the invention, operation is easy, is easy to control, and the production cycle greatly shortens, and efficiency mentions
Energy consumption and cost is also effectively reduced in height, is advantageously implemented industrialized production.
Detailed description of the invention
Fig. 1 is the transmission electron microscope photo for the middle carbon nanometer bainite steel board microstructure that the embodiment of the present invention 1 obtains.
Fig. 2 is the transmission electron microscope photo for the middle carbon nanometer bainite steel board microstructure that the embodiment of the present invention 3 obtains.
Fig. 3 is the transmission electron microscope photo for the middle carbon nanometer bainite steel board microstructure that the embodiment of the present invention 6 obtains.
Specific embodiment
Following embodiment is for the middle carbon nanometer bainite ultrahigh-strength steel plates and preparation method thereof that the present invention will be described in detail
And performance, to better understand the present invention.
Embodiment 1
According to chemical composition weight percent is C 0.58, Si 1.8, Mn 1.6, Mo 0.18, Ni 1.2, P 0.008, S
0.005, surplus is Fe and inevitable impurity, calculates ingredient proportion with vacuum induction furnace melting and pours into diameter
The ingot casting of 180mm, then vacuum consumable remelting derive from consumption ingot.By consumable ingot be heated to 1200 DEG C of heat preservation 60min carry out homogenization move back
Fire carries out hot rolling after coming out of the stove, and controls the finishing temperature of hot rolling at 850 DEG C, rolls rear slow cooling to room temperature, obtain the hot rolled plate of 20mm thickness
Base；Hot rolling slab is subjected to spheroidizing, that is, furnace cooling is come out of the stove air-cooled to room to 400 DEG C after being heated to 700 DEG C of 15 h of heat preservation
Temperature obtains annealing slab；Annealing slab is reheated to 880 DEG C of heat preservation 20min to come out of the stove, is put into 500 DEG C of salt bath furnaces cooling, guarantor
5min is held, samming is reached, the one-pass roller for carrying out that drafts is 30% immediately is taken out, is immediately placed in after rolling in 200 DEG C of salt bath furnaces
It keeps 15h to carry out bainite isothermal transformation, comes out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite ultrahigh-strength steel plates, detect
It was found that the ferrite bainite that the microstructure of carbon nanometer bainite ultrahigh-strength steel plates is 71nm by average thickness in above-mentioned gained
Ferrite (percent by volume 83.5%) and retained austenite (percent by volume 16.5%) composition.According to chinese national standard
GB/T 228.1-2010(metal material stretching test part 1: room temperature test method), measuring tensile strength is 2580MPa,
Elongation percentage is 7.4%.Measurement Vickers hardness is 682HV1.0.
Embodiment 2
According to step same as Example 1, the one-pass roller for being 30% until completing drafts is immediately placed in after rolling
It keeps 13h to carry out bainite isothermal transformation in 210 DEG C of salt bath furnaces, comes out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite superelevation
Strength steel sheet, the lath bainitic ferrite (percent by volume 17%) and remnants that microstructure is 85nm by average thickness
Austenite (percent by volume 83%) composition.According to chinese national standard GB/T 228.1-2010(metal material stretching test
Part 1: room temperature test method), measuring tensile strength is 2430MPa, elongation percentage 8.3%.Measuring Vickers hardness is
655HV1.0。
Embodiment 3
According to chemical composition weight percent is C 0.54, Si 1.7, Mn 1.9, Mo 0.24, Ni 1.63, P 0.005, S
0.002, surplus is Fe and inevitable impurity, calculates ingredient proportion with vacuum induction furnace melting and pours into diameter
The ingot casting of 180mm, then vacuum consumable remelting derive from consumption ingot.Consumable ingot is heated to 1220 DEG C of heat preservation 55min, is homogenized
Annealing, hot rolling of coming out of the stove control the finishing temperature of hot rolling at 900 DEG C, roll rear slow cooling to room temperature, obtain the hot rolling slab of 20mm thickness；
Hot rolling slab is subjected to spheroidizing, that is, furnace cooling is come out of the stove air-cooled to room temperature to 450 DEG C after being heated to 690 DEG C of 15 h of heat preservation,
Must anneal slab.Annealing slab is reheated to 890 DEG C of heat preservation 20min to come out of the stove, is put into 540 DEG C of salt bath furnaces cooling, holding
5min reaches samming, takes out the one-pass roller for carrying out that drafts is 40% immediately, is immediately placed in 205 DEG C of salt bath furnaces and protects after rolling
It holds 20h and carries out bainite isothermal transformation, come out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite ultrahigh-strength steel plates, it is microcosmic
The lath bainitic ferrite (percent by volume 78.4%) and retained austenite (volume hundred that tissue is 101nm by average thickness
Divide than being 21.6%) to form.According to chinese national standard GB/T 228.1-2010(metal material stretching test part 1: room temperature
Test method), measuring tensile strength is 2470MPa, elongation percentage 9.4%.Measurement Vickers hardness is 677HV1.0.
Embodiment 4
According to step same as Example 3, the one-pass roller for being 40% until completing drafts is immediately placed in after rolling
It keeps 18h to carry out bainite isothermal transformation in 215 DEG C of salt bath furnaces, comes out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite superelevation
Strength steel sheet, the lath bainitic ferrite (percent by volume 77%) and remnants that microstructure is 103nm by average thickness
Austenite (percent by volume 23%) composition.According to chinese national standard GB/T 228.1-2010(metal material stretching test
Part 1: room temperature test method), measuring tensile strength is 2390MPa, elongation percentage 10.1%.Measuring Vickers hardness is
637HV1.0。
Embodiment 5
According to chemical composition weight percent is C 0.52, Si 1.5, Mn 2.0, Mo 0.22, Ni1.7, P 0.007, S
0.004, surplus is Fe and inevitable impurity, calculates ingredient proportion with vacuum induction furnace melting and pours into diameter
The ingot casting of 180mm, then vacuum consumable remelting derive from consumption ingot.Consumable ingot is heated to 1220 DEG C of heat preservation 60min, is homogenized
Annealing, hot rolling of coming out of the stove control the finishing temperature of hot rolling at 930 DEG C, roll rear slow cooling to room temperature, obtain the hot rolling slab of 20mm thickness；
Hot rolling slab is subjected to spheroidizing, that is, furnace cooling is come out of the stove air-cooled to room temperature to 400 DEG C after being heated to 680 DEG C of 15 h of heat preservation,
Must anneal slab.Slab after spheroidizing is reheated to 900 DEG C of heat preservation 20min to come out of the stove, is put into 580 DEG C of salt bath furnaces and protects
5min is held, samming is reached, the one-pass roller for carrying out that drafts is 40% immediately is taken out, is immediately placed in after rolling in 210 DEG C of salt bath furnaces
It keeps 15h to carry out bainite isothermal transformation, comes out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite ultrahigh-strength steel plates, it is micro-
See lath bainitic ferrite (percent by volume 88%) and retained austenite (volume hundred that tissue is 70nm by average thickness
Divide than being 12%) to form.According to chinese national standard GB/T 228.1-2010(metal material stretching test part 1: room temperature examination
Proved recipe method), measuring tensile strength is 2480MPa, elongation percentage 6.5%.Measurement Vickers hardness is 661HV1.0.
Embodiment 6
According to step same as Example 5, the one-pass roller for being 40% until completing drafts is immediately placed in after rolling
It keeps 13h to carry out bainite isothermal transformation in 220 DEG C of salt bath furnaces, comes out of the stove and be air-cooled to room temperature, obtain middle carbon nanometer bainite superelevation
Strength steel sheet, microstructure by average thickness are the lath bainitic ferrite (percent by volume 85.3%) of 92nm and residual
Remaining austenite (percent by volume 14.7%) composition.According to chinese national standard GB/T 228.1-2010(material during tensile
Test part 1: room temperature test method), measuring tensile strength is 2380MPa, elongation percentage 9.5%.Measuring Vickers hardness is
629HV1.0。
In conclusion the preparation method of middle carbon nanometer bainite ultrahigh-strength steel plates provided by the invention, operates easy, appearance
Easy to control, the production cycle greatly shortens, and efficiency improves, obtained steel plate, and tensile strength is high, hardness is big, breaking elongation is excellent,
With high-intensitive, high-ductility, the good excellent combination mechanical property of welding performance, and it is at low cost, it is advantageously implemented industrial metaplasia
It produces.
Claims (8)
1. a kind of middle carbon nanometer bainite ultrahigh-strength steel plates, which is characterized in that the steel plate chemical quality percentage is as follows: C:
0.52 ~ 0.58%, Si:1.5 ~ 1.8%, Mn:1.6 ~ 2.0%, Mo:0.18 ~ 0.24%, Ni:1.2 ~ 1.7%, P: < 0.02%, S: <
0.02%, surplus is Fe and inevitable impurity, and the tensile strength of the steel plate is not less than not less than 2380 MPa, hardness
629HV1.0, breaking elongation be not less than 6.5%.
2. a kind of preparation method of middle carbon nanometer bainite ultrahigh-strength steel plates, which is characterized in that the chemical quality of the steel plate
Percentage is as follows: C:0.52 ~ 0.58%, Si:1.5 ~ 1.8%, Mn:1.6 ~ 2.0%, Mo:0.18 ~ 0.24%, Ni:1.2 ~ 1.7%, P: <
0.02%, S: < 0.02%, surplus is Fe and inevitable impurity；
The preparation method comprises the following steps:
(1) it melting: fed intake according to above-mentioned chemical component, melting and pour into ingot casting；
(2) consumable: carrying out vacuum consumable remelting for ingot casting, derives from consumption ingot；
(3) homogenizing annealing, hot rolling: being heated to 1150 ~ 1250 DEG C of heat preservation 50-70min homogenizing annealings for consumable ingot, then hot
It rolls and is cooled to room temperature, obtain hot rolling bar stock；
(4) spheroidizing: after hot rolling bar stock is heated to 680 ~ 750 DEG C of heat preservation 13-17 h, slow cooling to room temperature obtains annealing bar stock；
(5) ausrolling deformation and isothermal processes: being reheated to 880 ~ 930 DEG C of heat preservation 15-30 min for annealing bar stock, fast
Speed is transferred to cooling in 500-580 DEG C of salt bath furnace, takes out after samming and carries out one-pass roller rapidly into plate；It is transferred to 190 immediately again ~
13-20 h carries out isothermal processes in 240 DEG C of salt bath furnace, comes out of the stove and is air-cooled to room temperature, obtains middle carbon nanometer bainite unimach
Plate.
3. preparation method according to claim 2, which is characterized in that controlling hot rolling finishing temperature exists in the step (3)
850 ~ 930 DEG C, rear slow cooling is rolled to room temperature.
4. preparation method according to claim 2, which is characterized in that slow cooling to room temperature is first with furnace in the step (4)
It is cooled to 400-450 DEG C, then comes out of the stove and is air-cooled to room temperature.
5. preparation method according to claim 2, which is characterized in that salt bath furnace in step (5) Isothermal Treatment Process
Middle temperature control is at 200-220 DEG C.
6. preparation method according to claim 2, which is characterized in that roll control total deformation 30 in the step (5) ~
40%。
7. preparation method according to claim 2, which is characterized in that step (5) salt bath furnace controlled at 220 ~
240℃。
8. preparation method according to claim 2, which is characterized in that carbon nano-structured bainite unimach in described
2380 MPa or more of tensile strength, hardness 629HV1.0 or more, 6.5% or more the breaking elongation of plate.
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