CN109402355A - A kind of 600MPa grades of hot rolling TRIP type dual phase steel and preparation method thereof - Google Patents
A kind of 600MPa grades of hot rolling TRIP type dual phase steel and preparation method thereof Download PDFInfo
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- CN109402355A CN109402355A CN201811639349.4A CN201811639349A CN109402355A CN 109402355 A CN109402355 A CN 109402355A CN 201811639349 A CN201811639349 A CN 201811639349A CN 109402355 A CN109402355 A CN 109402355A
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D8/0226—Hot rolling
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- 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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- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Abstract
The present invention provides a kind of 600MPa grades of hot rolling TRIP type dual phase steels and preparation method thereof, it organizes to be retained austenite, martensite and ferrite, textura epidermoidea are as follows: the retained austenite of 4-6%, the martensite of 5-15%, remaining is ferrite, and has rodlike carbide in the ferrite；The steel subject organization are as follows: the retained austenite of 2-5%, the martensite of 25-40%, remaining is ferrite, and carbides-free is precipitated in the ferrite.The regulation plastic elongation intensity of steel of the present invention is 333-351MPa, and tensile strength 602-614MPa, elongation after fracture (80mm gauge length) is 23-25%.Steel of the invention can be applied to complicated automobile structure, chassis member, have preferable economy and application prospect.
Description
Technical field
The invention belongs to the advanced high-strength steel technical fields of Hot Rolling Automobile, and in particular to a kind of 600MPa grades of hot rolling TRIP type
Dual phase steel and preparation method thereof.
Background technique
Currently, the advanced high-strength steel of automobile hot rolling such as two-phase (DP) steel, phase-change induced plastic (TRIP) steel has been applied to vapour
The preparation of bassinet structure part.In the actual production process, it has been found that traditional dual phase steel on many high drawability parts at
Shape is difficult, it is difficult to meet the requirement of Automobile Design complexity punching structure part.And transformation induced plasticity steel is used, elongation percentage exists again
Certain surplus capacity causes to waste, and strength grade is higher, and weldability is poorer, but the retained austenite in TRIP steel is outside
The masterpiece used time, energy can be absorbed, undergoes phase transition induced plastic transformation, i.e. generation TRIP effect, improve safety coefficient.
Therefore the dual phase steel that a kind of high-intensitive, high ductibility has TRIP effect again is developed, not only can satisfy complicated punching press
The requirement of structural member, and there is preferable economic serviceability, safety.
Summary of the invention
In view of this, passing through group the present invention provides a kind of 600MPa grades of hot rolling TRIP type dual phase steel and preparation method thereof
The control of each phase component in knitting, the characteristics of making it have high intensity, high-elongation, TRIP effect.
First aspect present invention provides a kind of 600MPa grades of hot rolling TRIP type dual phase steel, including steel main body and covering steel master
The surface layer of body, the microstructure of the 600MPa grades of hot rolling TRIP type dual phase steel is by ferrite, martensite, three kinds of retained austenite
Phase composition；With volume percentage, the textura epidermoidea are as follows: the retained austenite of 4-6%, the martensite of 5-15%, remaining is
There is the ferrite of rodlike Carbide Precipitation；The steel subject organization are as follows: the retained austenite of 2-5%, the martensite of 25-40%,
Remaining is the ferrite that carbides-free is precipitated.
Preferably, average every within the scope of away from the 600MPa grades of hot rolling TRIP type two-phase steel surface 0-22 μ m thick
The quantity of rodlike carbide in 1000 square microns is 23-27；It is average every within the scope of away from surface 22-43 μ m thick
The quantity of rodlike carbide in 1000 square microns is 8-10；At 43 μm away from surface to thickness of strips half, nothing
Carbide Precipitation.Carbide Precipitation is in the trend gradually successively decreased, the direct shadow of carbide precipitate distribution trend within the scope of skin depth
Ring the formation of Steel Properties and retained austenite.
Preferably, the surface layer is 43 μm of span surface of steel plate of thickness range.
Preferably, the 600MPa grades of hot rolling TRIP type dual phase steel includes chemical component: by percentage to the quality, C
0.12-0.14%, Si 0.3-0.4%, Mn 1.5-1.7%, Al 0.35-0.45%, P≤0.014%, remaining is for Fe and not
Evitable impurity.
Preferably, the retained austenite is film-form.Film-form retained austenite is able to ascend the elongation percentage of steel.
Preferably, the regulation plastic elongation intensity of the 600MPa grades of hot rolling TRIP type dual phase steel is 333-351MPa, tension
Intensity is 602-614MPa, and the elongation after fracture under 80mm gauge length is 23-25%.
Second aspect of the present invention provides the preparation method of above-mentioned 600MPa grades of hot rolling TRIP type dual phase steel, and step includes:
S1, molten iron smelting cast to obtain the slab for meeting chemical component requirement, under inert gas protection heat slab
Heat preservation；
S2, the slab after heat preservation is controlled into hot rolling, obtains hot rolled strip；
S3, hot rolled strip is controlled into cooling, batches to obtain product.
The present invention is double by the TRIP type that heat preservation, hot rolling, cooling, the process flow batched form above-mentioned specific microstructure
Xiang Gang, coiling technique is conducive to the formation of film-form retained austenite after especially specific cooling.
Preferably, in step S1, the heat preservation is that slab is kept the temperature 1.5-2.5h at 1150-1250 DEG C, 99.99%
High pure nitrogen protection.Heat preservation makes steel temperature uniformity.
Preferably, in step S2, the control hot rolling includes the roughing of 2-3 passage and 3-5 passage finish rolling, the roughing stagnation pressure
Lower amount is 82-84%, and the finish rolling is at the uniform velocity rolled with the speed of 7-8m/s, and finish rolling overall reduction is 72-82%；The hot-rolled steel
Tape thickness is 4.3-4.7mm.Heat preservation and course of hot rolling influence carbide precipitate distribution trend in steel.
Preferably, in step S3, the control cooling step includes: with the ultrafast cooling velocity of 40-55 DEG C/s by step
Steel band water cooling obtained by S2 is to 690-710 DEG C, then air-cooled 20-30s, then again with the cooling velocity water cooling of 25-35 DEG C/s extremely
250-285℃；By steel strip coiling after cooling, then heap is cooled to room temperature.Cooling procedure influences steel surface layer and main body three-phase is multiple
Close the formation of phase.Water cooling before air-cooled terminates the excessively high ferrite volume fraction that can be reduced in tissue of temperature, reduces prolonging for steel plate
Stretch rate；Water cooling terminates the too low meeting of temperature so that ferrite volume fraction is excessive, reduces steel strength.Water cooling before batching terminates temperature
It spends low, can to form a large amount of martensite in tissue, steel plate elongation percentage is greatly reduced；It is excessively high and can make that water cooling terminates temperature
Deficiency is formed at martensite, reduces armor plate strength.
Compared with prior art, the invention has the following advantages that 600MPa grades of hot rolling TRIP type two-phase provided by the invention
The regulation plastic elongation intensity of steel is up to 333-351MPa, and tensile strength is up to 602-614MPa, elongation after fracture (80mm mark
Away from) up to 23-25%, it can be widely applied to complicated automobile structure, chassis member, not only can solve stamping process
The punching press problem of middle complexity, and have certain forming advantage in bending flange, Bulging Process, and may be used also when external force
TRIP effect occurs, safety coefficient is improved, there is preferable economic serviceability and application prospect.
Detailed description of the invention
Attached drawing 1 is morphology of carbides photo and power spectrum in the embodiment of the present invention 3.
Specific embodiment
To facilitate the understanding of the present invention, present invention work more comprehensively, is meticulously described below in conjunction with embodiment, but this hair
Bright protection scope is not limited to embodiment in detail below.
Unless otherwise defined, all technical terms used hereinafter and the normally understood meaning of those skilled in the art
It is identical.Technical term used herein is intended merely to the purpose of description specific embodiment, is not intended to the limitation present invention
Protection scope.
Unless otherwise specified, various raw material, reagent, the instrument and equipment etc. used in the present invention, can pass through
Market is commercially available or can be prepared by existing method.
First aspect present invention provides a kind of 600MPa grades of hot rolling TRIP type dual phase steel, including steel main body and covering steel master
The surface layer of body, the surface layer with a thickness of 43 μm.The microstructure of the 600MPa grades of hot rolling TRIP type dual phase steel by ferrite,
Three kinds of martensite, film-form retained austenite phase compositions；With volume percentage, the textura epidermoidea are as follows: the film-form of 4-6%
Retained austenite, the martensite of 5-15%, remaining is ferrite, and has rodlike carbide in the ferrite；The steel master
Body tissue are as follows: the film-form retained austenite of 2-5%, the martensite of 25-40%, remaining is ferrite, and in the ferrite
Middle carbides-free is precipitated.Specifically, the rodlike carbonization within the scope of away from surface 0-22 μ m thick, in average every 1000 square micron
The quantity of object is 23-27；Rodlike carbide within the scope of away from surface 22-43 μ m thick, in average every 1000 square micron
Quantity be 8-10；At 43 μm away from surface to thickness of strips half, carbides-free is precipitated.The change of TRIP type dual phase steel
Study point includes: C 0.12-0.14%, Si 0.3-0.4%, Mn 1.5-1.7%, Al 0.35- by percentage to the quality
0.45%, P≤0.014%, remaining is Fe and inevitable impurity.
The regulation plastic elongation intensity of above-mentioned 600MPa grades of hot rolling TRIP type dual phase steel is 333-351MPa, and tensile strength is
Elongation after fracture under 602-614MPa, 80mm gauge length is 23-25%.
Second aspect of the present invention provides the preparation method of above-mentioned 600MPa grades of hot rolling TRIP type dual phase steel, and step includes:
S1, molten iron smelting cast to obtain the slab for meeting chemical component requirement, will under 99.99% high pure nitrogen protection
Slab is heated to 1150-1250 DEG C and keeps the temperature 1.5-2.5h；
S2, the slab after heat preservation is controlled into hot rolling, the control hot rolling includes the roughing of 2-3 passage and 3-5 passage finish rolling, institute
Stating roughing overall reduction is 82-84%, and the finish rolling is at the uniform velocity rolled with the speed of 7-8m/s, and finish rolling overall reduction is 75-82%,
Obtain the hot rolled strip of thickness 4.3-4.7mm；
S3, hot rolled strip is cooled to 690-720 DEG C with the cooling velocity of 40-55 DEG C/s, then air-cooled 20-30s, then
250-280 DEG C is cooled to again with the cooling velocity of 35-35 DEG C/s；By steel strip coiling after cooling, then heap is cooled to room temperature and obtains
Product.
Below in conjunction with five specific embodiments to the 600MPa grade hot rolling TRIP type dual phase steel of the application and its preparation side
Method is described in detail.
Embodiment 1
A kind of preparation method of 600MPa grades of hot rolling TRIP type dual phase steel is present embodiments provided, step includes:
Slab is heated to 1200 DEG C of heat preservation 2h under 99.99% high pure nitrogen protection, with purity 99.99% when heating
Nitrogen protected.The chemical component of the slab forms are as follows: it is calculated in mass percent, C:0.124%, Si:0.39%,
Mn:1.67%, Alt:0.42%, P:0.014%, remaining is Fe and inevitable impurity.
By the slab after heating and thermal insulation in 1180 DEG C of beginning hot rollings, hot rolling technology is controlled are as follows: carry out 3 passage roughing, roughing
Overall reduction is 83%, then carries out 4 passage finish rolling, and the finish rolling is at the uniform velocity rolled with the speed of 7.5m/s, finish rolling extreme trace time entrance
Temperature is 880 DEG C, and finish rolling overall reduction is 79%, obtains the hot rolled strip of 4.5mm thickness；
Obtained hot rolled strip is subjected to control cooling, control hot rolled strip tissue is ferrite, martensite, residual austenite
Body three-phase contexture.Specific Controlled cooling process are as follows: then air-cooled with the cooling velocity of 50 DEG C/s by steel band water cooling to 700 DEG C
25s, then again with the cooling velocity of 30 DEG C/s by steel band water cooling to 275 DEG C；By steel strip coiling after cooling, then heap is cooled to room
Temperature obtains product.
The 600MPa grade hot rolling TRIP type dual phase steel being prepared using above-mentioned preparation method, microstructure by ferrite,
Three kinds of martensite, film-form retained austenite phase compositions.Each phase percentage (percent by volume, %) of textura epidermoidea are as follows: 4.8%
Retained austenite, 8.6% martensite, remaining is ferrite, there is rodlike carbide in ferrite.Outside skim-coat tissue
Steel subject organization each phase percentage are as follows: 2.5% retained austenite, 31% martensite, remaining is ferrite, carbon-free
Compound is precipitated；Within the scope of away from surface 0-22 μ m thick, the quantity of the rodlike carbide in average every 1000 square micron is 23
It is a；Within the scope of 22 μm -343 away from surface μ m thick, the quantity of the rodlike carbide in average every 1000 square micron is 10；
At the half away from the 43 μm-whole thickness in surface, without Carbide Precipitation；Retained austenite in tissue is film
Shape.
The regulation plastic elongation intensity for the hot-rolled dual-phase steel that the present embodiment obtains after measured is 351MPa, and tensile strength is
614MPa, elongation after fracture (80mm gauge length) are 23.5%.
Embodiment 2
A kind of 600MPa grades of hot rolling TRIP type dual phase steel is present embodiments provided, using system substantially the same manner as Example 1
Standby step, different is: its Chemical Composition in Cast Billet are as follows: is calculated in mass percent, C:0.131%, Si:0.36%, Mn:
1.55%, Alt:0.45%, P:0.012%, remaining is Fe and inevitable impurity.
Obtained 600MPa grade hot rolling TRIP type dual phase steel microstructure is by ferrite, martensite, film-form residual austenite
Three kinds of phase compositions of body.Each phase percentage (percent by volume, %) of textura epidermoidea are as follows: 5.2% retained austenite, 11% horse
Family name's body, remaining is ferrite, there is rodlike carbide in ferrite.Each phase hundred of the subject organization of steel outside skim-coat tissue
Divide ratio are as follows: 3.5% retained austenite, 38% martensite, remaining is ferrite, and carbides-free is precipitated；Away from surface 0-22 μ
In m thickness range, the quantity of the rodlike carbide in average every 1000 square micron is 26；In 22 μm -343 away from surface μ m-thick
It spends in range, the quantity of the rodlike carbide in average every 1000 square micron is 8；Away from the 43 μm-whole thickness in surface
At half, without Carbide Precipitation；Retained austenite in tissue is film-form.
The regulation plastic elongation intensity for the hot-rolled dual-phase steel that the present embodiment obtains after measured is 337MPa, and tensile strength is
613MPa, elongation after fracture (80mm gauge length) are 24.5%.
Embodiment 3
A kind of 600MPa grades of hot rolling TRIP type dual phase steel is present embodiments provided, using system substantially the same manner as Example 1
Standby step, different is: Chemical Composition in Cast Billet mass percent is C:0.136%, Si:0.34%, Mn:1.61%, Alt:
0.37%, P:0.014%, remaining is Fe and inevitable impurity.
Obtained 600MPa grade hot rolling TRIP type dual phase steel microstructure is by ferrite, martensite, film-form residual austenite
Three kinds of phase compositions of body.Each phase percentage (percent by volume, %) of textura epidermoidea are as follows: 4.4% retained austenite, 9% horse
Family name's body, remaining is ferrite, there is rodlike carbide in ferrite.Each phase hundred of the subject organization of steel outside skim-coat tissue
Divide ratio are as follows: 2.5% retained austenite, 29% martensite, remaining is ferrite, and carbides-free is precipitated；Away from surface 0-22 μ
In m thickness range, the quantity of the rodlike carbide in average every 1000 square micron is 27；In 22 μm -343 away from surface μ m-thick
It spends in range, the quantity of the rodlike carbide in average every 1000 square micron is 10；Away from the 43 μm-whole thickness in surface
At half, without rodlike Carbide Precipitation；Retained austenite in tissue is film-form.
The pattern photo of carbide and power spectrum are as shown in Fig. 1 in the present embodiment, and the corresponding specific data of power spectrum are such as in Fig. 1
Shown in table 1.
Carbide power spectrum in 1 embodiment 3 of table
The regulation plastic elongation intensity for the hot-rolled dual-phase steel that the present embodiment obtains after measured is 333MPa, and tensile strength is
602MPa, elongation after fracture (80mm gauge length) are 24%.
Comparative example 1
The dual phase steel Chemical Composition in Cast Billet that this comparative example provides is same as Example 3, using substantially the same manner as Example 3
Preparation step, different is: hot rolling uses+5 passage finish rolling of 2 passage roughing, and roughing overall reduction is 60%, under finish rolling stagnation pressure
77.5%, finish rolling 860 DEG C of inlet temperature of extreme trace time is air-cooled to 670 DEG C after finish rolling, then water cooling is batched to 450 DEG C, volume
Rear heap is taken to be cooled to room temperature.
The institute for the dual phase steel that this comparative example provides is organized by 55% ferrite and two kinds of bainite of 45% in a organized way
It constitutes, the regulation plastic elongation intensity of obtained hot-rolled dual-phase steel is 449MPa, tensile strength 592MPa, elongation after fracture
(80mm gauge length) is 20%.
In conjunction with the embodiment of the present invention and the chemical component preparation process and mechanical property of comparison it follows that institute of the present invention
There are embodiment better performances, the regulation plastic elongation intensity of obtained 600MPa grade hot rolling TRIP type dual phase steel is 333-
351MPa, tensile strength 602-614MPa, elongation after fracture (80mm gauge length) are 23-25%.Tissue is ferrite, geneva
Body, retained austenite three-phase contexture, and contain rodlike carbide in the ferritic structure of surface layer.The chemical component of comparative example although with
Embodiment is identical, but organizational controls is different, and obtained tissue is ferrite and bainite, and row's carbon is insufficient in ferrite, not formed
Retained austenite does not obtain lower regulation plastic elongation intensity, higher tensile strength and higher elongation percentage, and it is even more impossible to shapes
At TRIP effect.
Embodiment 4
A kind of preparation method of 600MPa grades of hot rolling TRIP type dual phase steel is present embodiments provided, step includes:
Slab is heated to 1180 DEG C of heat preservation 2.5h, when heating is protected with the nitrogen of purity 99.99%.The slab
Chemical component composition are as follows: be calculated in mass percent, C:0.124%, Si:0.39%, Mn:1.67%, Alt:0.42%, P:
0.014%, remaining is Fe and inevitable impurity.
By the slab after heating and thermal insulation in 1150 DEG C of beginning hot rollings, hot rolling technology is controlled are as follows: carry out 3 passage roughing, roughing
Overall reduction is 83%, then carries out 4 passage finish rolling, and the finish rolling is at the uniform velocity rolled with the speed of 7m/s, finish rolling extreme trace time entrance temperature
Degree is 850 DEG C, and finish rolling overall reduction is 76%, obtains the hot rolled strip of 4.7mm thickness；
Obtained hot rolled strip is subjected to control cooling, control hot rolled strip tissue is ferrite, martensite, residual austenite
Body three-phase contexture.Specific Controlled cooling process are as follows: be cooled to 690 DEG C with the cooling velocity of 52 DEG C/s, then air-cooled 20s, then
265 DEG C are cooled to again with the cooling velocity of 25 DEG C/s；By steel strip coiling after cooling, then heap is cooled to room temperature and obtains product.Institute
It obtains properties of product and embodiment 1 is almost the same.
Embodiment 5
A kind of preparation method of 600MPa grades of hot rolling TRIP type dual phase steel is present embodiments provided, step includes:
Slab is heated to 1250 DEG C of heat preservation 1.5h, when heating is protected with the nitrogen of purity 99.99%.The slab
Chemical component composition are as follows: be calculated in mass percent, C:0.124%, Si:0.39%, Mn:1.67%, Alt:0.42%, P:
0.014%, remaining is Fe and inevitable impurity.
By the slab after heating and thermal insulation in 1220 DEG C of beginning hot rollings, hot rolling technology is controlled are as follows: carry out 3 passage roughing, roughing
Overall reduction is 83%, then carries out 4 passage finish rolling, and the finish rolling is at the uniform velocity rolled with the speed of 8m/s, finish rolling extreme trace time entrance temperature
Degree is 860 DEG C, and finish rolling overall reduction is 82%, obtains the hot rolled strip of 4.3mm thickness；
Obtained hot rolled strip is subjected to control cooling, control hot rolled strip tissue is ferrite, martensite, residual austenite
Body three-phase contexture.Specific Controlled cooling process are as follows: then air-cooled with the cooling velocity of 45 DEG C/s by steel band water cooling to 710 DEG C
20s, then again with the cooling velocity of 28 DEG C/s by steel band water cooling to 275 DEG C；By steel strip coiling after cooling, then heap is cooled to room
Temperature obtains product.Products obtained therefrom performance and embodiment 1 are almost the same.
Although preferred embodiments of the present invention have been described, it is created once a person skilled in the art knows basic
Property concept, then additional changes and modifications may be made to these embodiments.So it includes excellent that the following claims are intended to be interpreted as
It selects embodiment and falls into all change and modification of the scope of the invention.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range.In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (10)
1. a kind of 600MPa grades of hot rolling TRIP type dual phase steel, the surface layer including steel main body and covering steel main body, it is characterised in that: institute
The microstructure of 600MPa grades of hot rolling TRIP type dual phase steels is stated by three kinds of ferrite, martensite, retained austenite phase compositions；With body
Product percentages, the textura epidermoidea are as follows: the retained austenite of 4-6%, the martensite of 5-15%, remaining is to have rodlike carbide
The ferrite of precipitation；The steel subject organization are as follows: the retained austenite of 2-5%, the martensite of 25-40%, remaining is Non-carbonized
The ferrite that object is precipitated.
2. 600MPa grades of hot rolling TRIP type dual phase steel as described in claim 1, it is characterised in that: away from the 600MPa grades of heat
It rolls within the scope of TRIP type two-phase steel surface 0-22 μ m thick, the quantity of the rodlike carbide in average every 1000 square micron is
23-27；Within the scope of away from surface 22-43 μ m thick, the quantity of the rodlike carbide in average every 1000 square micron is 8-
10；At 43 μm away from surface to thickness of strips half, carbides-free is precipitated.
3. 600MPa grades of hot rolling TRIP type dual phase steel as described in claim 1, it is characterised in that: the surface layer is span steel plate
The thickness range that 43 μm of surface.
4. 600MPa described in claim 1- grades of hot rolling TRIP type dual phase steel, it is characterised in that: by percentage to the quality, including
Chemical component: C 0.12-0.14%, Si 0.3-0.4%, Mn 1.5-1.7%, Al0.35-0.45%, P≤0.014%,
Remaining is Fe and inevitable impurity.
5. the 600MPa grade hot rolling TRIP type dual phase steel as described in any one of claim 1-4 claim, it is characterised in that: institute
Stating retained austenite is film-form.
6. 600MPa grades of hot rolling TRIP type dual phase steel as described in claim 1, it is characterised in that: the 600MPa grades of hot rolling TRIP
The regulation plastic elongation intensity of type dual phase steel is 333-351MPa, having no progeny under tensile strength 602-614MPa, 80mm gauge length
Elongation is 23-25%.
7. the preparation method of 600MPa described in claim 1 grades of hot rolling TRIP type dual phase steel, step include:
S1, molten iron smelting cast to obtain the slab for meeting chemical component requirement, and slab is heated and protected under inert gas protection
Temperature；
S2, the slab after heat preservation is controlled into hot rolling, obtains hot rolled strip；
S3, hot rolled strip is controlled into cooling, batches to obtain product.
8. the preparation method of 600MPa grades of hot rolling TRIP type dual phase steel as claimed in claim 7, it is characterised in that: in step S1,
For slab is kept the temperature 1.5-2.5h at 1150-1250 DEG C, 99.99% high pure nitrogen is protected for the heat preservation.
9. the preparation method of 600MPa grades of hot rolling TRIP type dual phase steel as claimed in claim 7, it is characterised in that: step S2
In, the control hot rolling includes the roughing of 2-3 passage and 3-5 passage finish rolling, and the roughing overall reduction is 82-84%, the essence
It rolls and is at the uniform velocity rolled with the speed of 9m/s, finish rolling overall reduction is 75-82%；The hot rolled strip thickness 4.3-4.7mm.
10. the preparation method of 600MPa grades of hot rolling TRIP type dual phase steel as claimed in claim 9, it is characterised in that: step S3
In, the control cooling step includes: by steel band water cooling obtained by step S2 with the cooling velocity of 40-55 DEG C/s to 690-720 DEG C,
Then air-cooled 20-30s, then again with the cooling velocity water cooling of 25-35 DEG C/s to 250-285 DEG C；By steel strip coiling after cooling,
Then heap is cooled to room temperature.
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