CN107964624A - A kind of yield strength 500MPa level structure steel and preparation method thereof - Google Patents
A kind of yield strength 500MPa level structure steel 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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- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
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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
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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
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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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- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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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
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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
- C21D2211/009—Pearlite
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a kind of yield strength 500MPa level structure steel and preparation method thereof, the production cost that mainly solves yield strength 500MPa level structures steel in the prior art is high, the technical problem of welding performance and poor mechanical property.Yield strength 500MPa level structure steel provided by the invention, its chemical component weight percentage are：C：0.07 0.09%, Si：0 0.1%, Mn：1.5 1.7%, S≤0.005%, P≤0.015%, Nb：0.03 0.05%, Ti：0.03 0.05%, Mg：0.0005 0.0030%, Al：0.01 0.04%, N≤0.006%, surplus is Fe and inevitable impurity.Upper yield strength >=500Mpa of hot rolled steel plate of the present invention, elongation after fracture >=19%；It is mainly used for the fields such as automobile, vessel, engineering machinery.
Description
Technical field
The present invention relates to a kind of structural steel, more particularly to a kind of yield strength 500MPa level structure steel and preparation method thereof,
Belong to technical field of iron-base alloy.
Background technology
With the lightweight of all kinds of steel products, the high-strength loss of weight of steel becomes trend, and the surrender as intermediate level is strong
500MPa grades of high-strength steel of degree are widely used in the fields such as automobile, vessel, bridge and engineering machinery.Due to widely used, each field
It is different to the performance requirement of material, such as surface quality, welding performance, mechanical property etc..
The failure main cause such as cracking is with Al caused by during existing yield strength 500MPa grades of steel plates processing2O3Based on
Brittle non-metal field trash becomes origin or the crack propagation of crackle at stress concentration position under conditions of processing or load
Direction.Therefore, inclusion conditioning is to control steel inclusion size, form and composition to become to improve the important of mechanical property of steel plate
Approach.
Inclusion conditioning technique Calcium treatment requires height to the dissolved aluminum of calcium alloy feed quantity and molten steel, and feeding is excessive or very few
Calcium alloy can all generate high-melting-point, be not easy the aluminum calcium salt that floats.Simultaneously as generation aluminum calcium salt contact angle compared with
It is small, easily collide, grow up in molten steel, form large-sized field trash, cannot such as float in time, the mechanical property of hot rolling can be deteriorated
Energy.To compare, the product of inclusion conditioning technology magnesium treatment process is tiny, disperse, and is not easy to polymerize, meanwhile, and Ti compound actions,
The Oxide Metallurgy effect of inclusion particle is played, strand edge crystal grain is refined, reduces strand corner crack so that hot rolled steel plate
Surface is good.
Application publication number is that the Chinese patent application file of CN105063509A discloses a kind of yield strength 500MPa grades
Structural steel for bridge and its production method, containing high-valency metals such as Cr, Mo in design, design cost is high, while in embodiment
Mn contents are above 1.5wt% substantially.Hotplate surface quality is not referred to.
The Chinese patent application file of application publication number CN102839321A discloses a kind of yield strength >=500MPa grades
Ultrathin hot rolled strip and its manufacture method, reach crystal grain thinning by higher hot-rolling laminar cooling velocity, suppress TiC in crystal boundary
Separate out, have the characteristics that composition design cost is low.But the steel plate obtained by the method, unstable mechanical property, elongation is slightly
It is low.
The Chinese patent application file of application publication number CN105177421A discloses a kind of yield strength as 500MPa grades
Other forklift truck transverse beam steel plate special and preparation method thereof, applied to cut deal, hot-rolled product is using preceding needing normalizing.
Disclosed yield strength 500MPa grades of production method in the prior art, all considers by molten steel Calcium treatment technique
Field trash is modified, achievees the purpose that to obtain clean steel；Existing Calcium treatment is only conducive to inclusion conditioning, removes, does not have
The function of Oxide Metallurgy.
The content of the invention
The object of the present invention is to provide a kind of yield strength 500MPa level structure steel and preparation method thereof, mainly solve existing
The technical problem of the production cost height of yield strength 500MPa level structure steel, welding performance and poor mechanical property in technology.
The technical solution adopted by the present invention is：A kind of yield strength 500MPa level structure steel, its chemical component weight percentage
Than for：C：0.07-0.09%, Si：0-0.1%, Mn：1.5-1.7%, S≤0.005%, P≤0.015%, Nb：0.03-
0.05%, Ti：0.03-0.05%, Mg：0.0005-0.0030%, Al：0.01-0.04%, N≤0.006%, surplus for Fe and
Inevitable impurity.
The metallographic structure of yield strength 500MPa level structure steel of the present invention is fine ferrite grain+a small amount of pearlite, and tissue is brilliant
Granularity level is 10.0~11.5 grades, its 2.0~6.0mm thickness hot rolled steel plate upper yield strength ReH>=500Mpa, tensile strength Rm
>=600Mpa, elongation after fracture A >=19%.
The reasons why chemical composition of yield strength 500MPa level structure steel of the present invention limits within the above range is such as
Under：
Carbon：Carbon is acted on by solution strengthening and precipitation strength, improves the intensity of steel, but carbon content is excessive, to plasticity
It is unfavorable with toughness, and center segregation is easily produced, it is unfavorable to bending property, also it is unfavorable for welding processing.Carbon content is too low, in order to
Reach predetermined strength, it is necessary to add a large amount of alloys and make up, increase cost of alloy.C content of the present invention is limited to 0.07~0.09%.
Silicon：There is significant reinforcing effect in silicon solid solution ferrite, but silicone content is excessive unfavorable to toughness and surface quality, especially
It is to be formed to be difficult to the red iron sheet that removes in hot rolled sheet metal surface, influences appearance and sequent surface processing.Present component designs
In, silicon-containing alloy is not added additionally, limits Si contents as 0-0.1%.
Manganese：Manganese is a kind of economical, hence it is evident that improves one of alloying element of intensity, while can improve the quenching degree of steel plate.Manganese
To the adverse effect of welding performance, the 1/6 of carbon content is only about.Therefore, the addition of manganese can reduce the addition of carbon, improve steel plate
Intensity, while reduce influence to welding performance.The present invention limits Mn contents as 1.5%~1.7%.
Sulphur and phosphorus：Sulphur and P elements deteriorate toughness and plasticity, cause " hot-short " and " cold short " in low-alloy high-strength steel.
But Liu can increase steel-making difficulty and cost He Lin composition design is too low.For this reason, the present invention restriction S≤0.005%, P≤
0.015%.
Niobium：Niobium can improve the recrystallization temperature of steel, and hot rolling can carry out under the austenitizing temperature of higher, thinner to obtain
Small austenite structure；Meanwhile Nb and C, N in steel etc. forms carbon, nitrogen compound, nail austenite grain is pricked, hinders austenite
Crystal grain is grown up, and refines austenite structure, and plays precipitation enhancement, improves the intensity and low-temperature flexibility of steel plate.Nb content mistakes
Height, it is excessive to be easy to cause yield tensile ratio, influences unobvious again when too low on recrystallization temperature.Therefore, the present invention limit Nb contents as
0.03-0.05%.
Titanium：A kind of strong N and deoxidant element, just form TiN in sheet billet continuous casting high temperature, hinder the original of continuous casting billet during titanium
Austenite Grain Growth, crystal grain thinning.Meanwhile Ti (C, N) is separated out in low temperature, precipitation strength improves material yield strength and tough
Property.In the present invention, Ti and the Mg of addition react, and generate compound (Ti, Mg) oxide and are mingled with, its fusion temperature is high, in height
Wen Shike suppresses Austenite Grain Growth, acicular ferrite can be promoted to grow in low temperature as forming core core.The present invention limits
Ti contents are 0.03-0.05%.
Magnesium：Magnesium processing is mingled with refinement, inclusion conditioning and promotion acicular ferrite growth and other effects.In magnesium and molten steel
Al2O3Tiny magnesium aluminate spinel being formed, since contact angle is big, it is not easy to focusing is grown up, and reaches the effect of refinement field trash,
The cleanliness factor of molten steel is improved, improves the comprehensive mechanical property of steel plate.The fusing point of the field trash containing Mg is high, with Ti compound actions, plays
The Oxide Metallurgy effect of inclusion particle, refines strand edge crystal grain, reduces strand corner crack so that hot rolled sheet metal surface
Well.Content of magnesium in molten steel starts to play the role of refining field trash 0.0005%, if the content of magnesium of addition surpasses
0.003% is crossed, pure MgO is easily formed and is mingled with, deteriorate the cleanliness factor of molten steel.The present invention limit Mg contents as 0.0005%~
0.0030%.
Nitrogen：Nitrogen content height can deteriorate the plasticity and toughness of material, especially for Ti micro-alloyed high strength steel, due to N with
The combination power of Ti is very strong, occurs too early in continuous casting, forms large-sized TiN particles, consumes Ti elements, reduces toughness, at the same time
Hot rolling TiC precipitated phases are reduced, reduce intensity；Therefore, the present invention limits N≤0.006%.
The manufacture method of above-mentioned yield strength 500MPa level structure steel, this method include：
1) molten steel for meeting steel chemical composition requirement of the present invention is obtained by converter melting；Enter the weight hundred of stove Sulfur Content in Hot Iron
Divide content≤0.002%, hot metal ratio >=90% of converter smelting, the weight content for bessemerizing oxygen in endpoint molten steel is less than
800ppm, liquid steel temperature during converter tapping are 1650-1680 DEG C, and aluminium is added in the molten steel in converter tapping process into ladle
0.5-1.5kg/ tons of steel of base deoxidier, add 2-3kg/ tons of steel of lime；
2) molten steel in ladle is transported to refining furnace and carries out liquid steel temperature regulation and control and alloy elements regulation；Manganeisen is pressed
Design content all to add, refining furnace liquid steel refining is completed after ladle bottom blowing argon gas time >=5min；
3) by the molten steel in ladle be transported to RH stoves carry out refining treatment, to molten steel carry out Fruit storage, RH stoves it is true
Reciprocal of duty cycle≤270Pa, pure degassing time >=10min, adds Nb, Ti in ferro-titanium, ferrocolumbium regulation and control molten steel and contains to design afterwards
Amount, circulation are circulation time >=5min in the case of 1600~3000L/min；After RH stoves release vacuum, with 1.5-4m/s's
Wire-feeding velocity feeds the chemical composition of aluminum-magnesium alloy wire regulation and control molten steel to designing content, steel ladle bottom argon blowing in the molten steel into ladle
The gas time >=5min；The percentage by weight of the aluminum-magnesium alloy wire chemical composition is：Mg：8%-15%, Al：30%-50%, it is remaining
Measure as Fe and inevitable impurity；
4) molten steel it will carry out sheet billet continuous casting after RH stove refining treatments and obtain continuous casting steel billet, the slab pulling rate in casting process
For 0.8-2.4m/min, the percentage by weight of continuous casting steel billet chemical composition is：C：0.07-0.09%, Si：0-0.1%, Mn：
1.5-1.7%, S≤0.005%, P≤0.015%, Nb：0.03-0.05%, Ti：0.03-0.05%, Mg：0.0005-
0.0030%, Al：0.01-0.04%, N≤0.006%, surplus are Fe and inevitable impurity；
5) continuous casting steel billet carries out hot rolling, the hot rolling is two sections in 1200 DEG C~1240 DEG C after heating 180~240min
Formula rolling mill practice, roughing are 6 passage tandem rollings, are rolled more than austenite recrystallization temperature, roughing start temperature for 1050 DEG C~
1090 DEG C, roughing end temp is 1020 DEG C~1050 DEG C；Finish rolling is 7 passage tandem rollings, is rolled in austenite non-recrystallization humidity province
System, finish rolling end temp are 820~860 DEG C；After finish rolling, steel plate thickness is 2.0~6.0mm, and section cooling is cooled down using leading portion,
Coiling temperature batches to obtain coils of hot-rolled steel when being 520~560 DEG C.
The reasons why process system that the present invention takes, is as follows：
1st, in RH stoves refining process, magnesium alloy is added into molten steel, using magnesium handle method to field trash into
Row is modified.Magnesium treatment process controls field trash, and the field trash of generation is magnesium aluminate spinel, it is not easy polymerization and grows up, and can refine folder
Debris；While the composite oxides and nitride of Mg and Ti formation are tiny, disperse, promote Intragranular Acicular Ferrite to be formed, possess oxidation
The effect of thing metallurgy, 20-40MPa can be improved by producing the yield strength of tapping.
2nd, continuous casting steel billet heating process is set
Being set at for continuous casting steel billet acid extraction ensures the molten of the particles such as TiN, TiC thick in continuous casting billet
Solution.The particles such as thick TiN, TiC are completely dissolved in austenite grain, cooling procedure diffusion-precipitation, tiny after rolling
The particle such as TiC, TiN, play the effect of precipitation strength.Heating-up temperature is too low or heating time is too short, original in continuous casting steel billet
The particles such as thick TiN, TiC cannot fully dissolve；But heating-up temperature is excessive or heating time is long, slab original structure is thick
Greatly, surface oxidation decarburization is serious, is unfavorable for steel plate final performance and surface quality, while also consume the energy.Present invention setting connects
It is 1200~1240 DEG C to cast slab heating temperature, and heating time is 150~240min.
3rd, roughing end temp is set
Rolling process of rough rolling control rolls more than austenite recrystallization temperature, it is ensured that austenite is after deformation and recrystallization
Obtain uniformly tiny austenite grain.Therefore the present invention sets roughing end temp as 1050 DEG C~1090 DEG C.
4th, finish rolling end temp is set
The final rolling temperature basis of design of the present invention has two, and one cannot be excessive for final rolling temperature setting, but in austenite
Unhydrated cement rolls, and the austenite grain deformed, elongated, is transformed into tiny ferrite crystal grain in cooling procedure,
Play refined crystalline strengthening；Two cannot be too low for final rolling temperature setting, and low final rolling temperature easily makes the particles such as TiC deform in advance
Separated out in austenite, particle is thick, and the small and dispersed TiC particles separated out in ferrite are reduced, and influence precipitating reinforcing effect.
Therefore the present invention sets finish rolling end temp as 820~860 DEG C.
5th, hot-rolling coiling temperature is set
The setting of hot-rolling coiling temperature mainly makes the reinforcing effect of consideration secondary precipitation particle phase and grain size grow up, its table
It is now the performance and tissue of material.Coiling temperature height is conducive to Ti, Nb alloy carbon, the particle secondary phase of nitrogen separates out, but easily leads
Cause matrix ferritic structure to grow up, reduce the toughness of steel plate；Coiling temperature is too low, the particle secondary phase analysis of Ti, Nb alloy carbon, nitrogen
Go out suppressed, the precipitating reinforcing effect for improving armor plate strength is bad.Consider, the present invention sets hot-rolling coiling temperature as 520
~560 DEG C.
The metallographic structure of the yield strength 500MPa level structure steel of the method for the present invention production is fine ferrite grain+a small amount of pearly-lustre
Body, tissue grain size number are 10.0~11.5 grades, its 2.0~6.0mm thickness hot rolled steel plate upper yield strength ReH>=500Mpa, resists
Tensile strength Rm>=600Mpa, elongation after fracture A >=19%.
The present invention has following good effect compared with prior art：1st, RH stoves liquid steel refining process of the present invention, using being mingled with
The processing of thing modification technology magnesium replaces traditional inclusion conditioning technology Calcium treatment, and magnesium processing possesses inclusion conditioning and oxide smelting
Golden dual-use function, makes steel inclusion small and dispersed, improves the cleanliness factor of molten steel.2nd, the magnesium processing that the present invention uses promotes transgranular
Acicular ferrite is grown, and improves the yield strength and tensile strength of the plasticity and toughness, especially steel plate of steel plate, than using at calcium
Science and engineering skill, the present invention in alloy Mn contents in the case where reducing 0.1wt%, yield strength and the high 20-40MPa of tensile strength,
Cost of alloy is low.3rd, the present invention uses magnesium treatment process, and in casting process, in continuous casting billet corner, generation is tiny is mingled with containing magnesium
Thing, refines corner crystal grain, improves high-temp plastic, reduces continuous casting billet transverse corner crack line, reaches and reduces the hair that hot rolling plate surface sticks up skin
It is raw, improve hot rolled plate surface quality.4th, compared with traditional Calcium treatment technique, using magnesium handle can yield strength and tensile strength,
The addition of other alloys is reduced accordingly, reduces cost of alloy.5th, in molten iron pretreatment and converter control sulfur content, ensure
Refining furnace (LF stoves) not desulfurization, reduces N increases, reduces continuous casting billet transverse corner crack line and occurs, while controls free oxygen content, reduces
Deoxidation type inclusion generates.
Brief description of the drawings
Fig. 1 is the metallographic structure photo of hot rolled steel plate embodiment 1 of the present invention.
Fig. 2 is the field trash photo of 1 hot rolled steel plate of the embodiment of the present invention.
Embodiment
With reference to embodiment 1~3, the present invention will be further described.
The molten iron inclusion quantity for being used to contain molten iron in the embodiment of the present invention is 250 tons.
Table 1 is the chemical composition (by weight percentage) of steel of the embodiment of the present invention, and surplus is iron and inevitable impurity.
The chemical composition of 1 steel of the embodiment of the present invention of table, unit：Percentage by weight.
| Element | C | Si | Mn | P | S | Nb | Ti | AL | Mg | N |
| Embodiment 1 | 0.075 | 0.030 | 1.51 | 0.015 | 0.0025 | 0.039 | 0.036 | 0.022 | 0.0007 | 0.0032 |
| Embodiment 2 | 0.074 | 0.068 | 1.53 | 0.010 | 0.0015 | 0.041 | 0.033 | 0.024 | 0.0010 | 0.0042 |
| Embodiment 3 | 0.079 | 0.051 | 1.55 | 0.012 | 0.0005 | 0.040 | 0.038 | 0.025 | 0.0013 | 0.0048 |
The molten steel for meeting chemical composition requirement is obtained by converter melting, the refined stove refining procedure of molten steel blows Ar processing,
RH stoves carry out vacuum circulation degassing processing and trimming, and the rear sheet billet continuous casting that carries out obtains continuous casting steel billet；Continuous casting steel billet thickness is
210~230mm, width are 900~1600mm, and length is 8500~11000mm.
The scale slab of STEELMAKING PRODUCTION send to heating furnace and reheats, and send to hot tandem and rolls after de-scaling of coming out of the stove.Pass through
Roughing and finish rolling Continuous mill train controlled rolling, are batched after section cooling, and section cooling takes leading portion to cool down, and output is qualified
Coils of hot-rolled steel.The thickness of hot rolled steel plate is 2.0~6.0mm.Hot rolling technology control parameter is shown in Table 2.
2 hot rolling technology control parameter of the embodiment of the present invention of table
The yield strength 500MPa level structure steel obtained using the above method, referring to Fig. 1, the metallographic structure of hot rolled steel plate is
Fine ferrite grain+a small amount of pearlite, tissue grain size number are 10.0~11.5 grades；Referring to Fig. 2, the method for the present invention is using at magnesium
The method of reason is modified field trash, promotes Intragranular Acicular Ferrite and is formed, the field trash small and dispersed of hot rolled steel plate；It 2.0
~6.0mm thickness hot rolled steel plate upper yield strengths ReH>=500Mpa, tensile strength Rm>=600Mpa, elongation after fracture A >=19%, table
Face quality is good.
By the obtained hot rolled steel plate of the present invention according to《GB/T228.1-2010 metal material stretching test part 1s：Room temperature
Test method》Tension test is carried out, its mechanical property is shown in Table 3.
The mechanical property of 3 hot rolled steel plate of the embodiment of the present invention of table
| Performance indicator | Upper yield strength/MPa | Tensile strength/MPa | Elongation after fracture A/% |
| Embodiment 1 | 583 | 671 | 26 |
| Embodiment 2 | 596 | 680 | 29 |
| Embodiment 3 | 579 | 668 | 28 |
In addition to the implementation, the present invention can also have other embodiment.It is all to use equivalent substitution or equivalent transformation shape
Into technical solution, all fall within the protection domains of application claims.
Claims (4)
1. a kind of yield strength 500MPa level structure steel, its chemical component weight percentage are：C：0.07-0.09%, Si：0-
0.1%, Mn：1.5-1.7%, S≤0.005%, P≤0.015%, Nb：0.03-0.05%, Ti：0.03-0.05%, Mg：
0.0005-0.0030%, Al：0.01-0.04%, N≤0.006%, surplus are Fe and inevitable impurity；Hot rolled steel plate
Metallographic structure is fine ferrite grain+a small amount of pearlite, and the tissue grain size is 10~11.5 grades.
2. yield strength 500MPa level structure steel as claimed in claim 1, it is characterized in that, on 2.0~6.0mm thickness hot rolled steel plates
Yield strength ReH>=500Mpa, tensile strength Rm>=600Mpa, elongation after fracture A >=19%.
3. a kind of manufacture method of yield strength 500MPa level structure steel, this method include：
1) molten steel for meeting steel chemical composition requirement of the present invention is obtained by converter melting；The weight percent for entering stove Sulfur Content in Hot Iron contains
Amount≤0.002%, hot metal ratio >=90% of converter smelting, the weight content for bessemerizing oxygen in endpoint molten steel is less than 800ppm,
Liquid steel temperature during converter tapping is 1650-1680 DEG C, and aluminium base deoxidation is added in the molten steel in converter tapping process into ladle
0.5-1.5kg/ tons of steel of agent, add 2-3kg/ tons of steel of lime；
2) molten steel in ladle is transported to refining furnace and carries out liquid steel temperature regulation and control and alloy elements regulation；By manganeisen by design
Content all adds, and refining furnace liquid steel refining is completed after ladle bottom blowing argon gas time >=5min；
3) molten steel in ladle is transported to RH stoves and carries out refining treatment, Fruit storage, the vacuum of RH stoves are carried out to molten steel
≤ 270Pa, pure degassing time >=10min, add in ferro-titanium, ferrocolumbium regulation and control molten steel Nb, Ti to designing content, ring afterwards
Flow is circulation time >=5min in the case of 1600~3000L/min；After RH stoves release vacuum, with the line feeding speed of 1.5-4m/s
The chemical composition for feeding aluminum-magnesium alloy wire regulation and control molten steel is spent in the molten steel into ladle to designing content, ladle bottom blowing argon gas time
≥5min；The percentage by weight of the aluminum-magnesium alloy wire chemical composition is：Mg：8%-15%, Al：30%-50%, surplus Fe
And inevitable impurity；
4) molten steel it will carry out sheet billet continuous casting after RH stove refining treatments and obtain continuous casting steel billet, the slab pulling rate in casting process is
0.8-2.4m/min, the percentage by weight of continuous casting steel billet chemical composition are：C：0.07-0.09%, Si：0-0.1%, Mn：1.5-
1.7%, S≤0.005%, P≤0.015%, Nb：0.03-0.05%, Ti：0.03-0.05%, Mg：0.0005-0.0030%,
Al：0.01-0.04%, N≤0.006%, surplus are Fe and inevitable impurity；
5) continuous casting steel billet carries out hot rolling, the hot rolling is rolled for two-part in 1200 DEG C~1240 DEG C after heating 180~240min
Technique processed, roughing are 6 passage tandem rollings, are rolled more than austenite recrystallization temperature, and roughing start temperature is 1050 DEG C~1090
DEG C, roughing end temp is 1020 DEG C~1050 DEG C；Finish rolling is 7 passage tandem rollings, is rolled in austenite non-recrystallization humidity province, essence
End temp is rolled for 820~860 DEG C；After finish rolling, section cooling is cooled down using leading portion, and coiling temperature batches when being 520~560 DEG C
Obtain coils of hot-rolled steel.
4. the manufacture method of yield strength 500MPa level structure steel as claimed in claim 3, it is characterized in that, after finish rolling, control
Steel plate thickness is 2.0~6.0mm.
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| CN109628693A (en) * | 2019-01-28 | 2019-04-16 | 苏州大学 | A kind of low cost magnesium processing micro alloyed steel and preparation method thereof |
| CN110656219A (en) * | 2018-06-29 | 2020-01-07 | 上海梅山钢铁股份有限公司 | Method for controlling center segregation of fine blanking steel 40MnB continuous casting slab |
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