CN105839003B - A kind of 180~200mm thickness EH36 steel plates of normalizing state delivery and preparation method thereof - Google Patents

A kind of 180~200mm thickness EH36 steel plates of normalizing state delivery and preparation method thereof Download PDF

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CN105839003B
CN105839003B CN201610374131.5A CN201610374131A CN105839003B CN 105839003 B CN105839003 B CN 105839003B CN 201610374131 A CN201610374131 A CN 201610374131A CN 105839003 B CN105839003 B CN 105839003B
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steel
thickness
rolling
steel plate
normalizing
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CN201610374131.5A
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CN105839003A (en
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刘朝霞
阮小江
苗丕峰
赵孚
白云
刘俊
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江阴兴澄特种钢铁有限公司
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26Methods of annealing
    • C21D1/28Normalising
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226Hot rolling
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C33/00Making ferrous alloys
    • C22C33/04Making ferrous alloys by melting
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/08Ferrous alloys, e.g. steel alloys containing nickel
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/005Ferrite
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/009Pearlite
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

Abstract

The present invention relates to 180~200mm thickness EH36 steel plates of a kind of normalizing state delivery and preparation method thereof, the chemical composition of steel plate is based on standard GB/T 712 or classification society rule, and substitute element Ti addition is liked using Al, while adding the V of high relative contents.Manufacture method includes electric furnace smelting, LF refining, VD refinings, molding, Heating Steel Ingots, split rolling method, control slow cooling, heating steel billet, rolling and normalized treatment carried out successively etc..Obvious gradient structure is not present in thickness direction in the steel plate of acquisition, and steel plate tissue is mainly based on ferritic-pearlitic, the mixing tissue supplemented by a small amount of bainite.Microscopic structure fine uniform, average grain size is 8 12 μm;Yield strength is between 380~430MPa, and tensile strength is between 550~600MPa, and elongation percentage is moderate.The J of 40 DEG C of notched bar impact strengths at steel plate 1/4, at 1/2 >=60, comprehensive mechanical property is excellent.

Description

A kind of 180~200mm thickness EH36 steel plates of normalizing state delivery and preparation method thereof
Technical field
The invention belongs to field of steel metallurgy, and in particular to a kind of special thickness 180~200mm EH36 steel of normalizing state delivery And its production method.
Background technology
At present, it is related to the security of ocean operation, Hai Gong enterprises are for the such key positions of 180~200mm EH36 Special heavy plate is still taken based on foreign countries' introduction.Main cause is that the country possesses the enterprise of production 180~200mm super-thick steel plates extremely It is a small number of.For the EH36 steel plate for ocean engineering of the normalizing state delivery of high standard, domestic technique under-reserve.
At present, ocean engineering is primarily present two big difficult points with the production of high strength special heavy plate:First, welded and low to meet The requirement of warm toughness, it is necessary to ensure that the composition design of low-carbon-equivalent, it is therefore necessary to the super thick slab or steel ingot of supporting high homogeneous Deng.Improve compression ratio, it is ensured that armor plate strength.2nd, the product of more than 150mm thickness can be followed without applicable codes and standards.The whole world Eight state's specifications provide that the maximum gauge of involved steel plate is 100mm, Norske Veritas in classification society of general nine state(DNV)Most thickness is 150mm, the corresponding maximum gauge of standard GB/T 712~2011 is 150mm.In nine classification society rules of state and national standard In GB712, the production for EH36 grade of steels is main with conditions of delivery such as controlled rolling, TMCP, hot rolling, normalizing rolling, normalizings.Currently, Extra large work ship enterprise produces 180 still based on the composition design and requirement suitable for 6~100mm or 6~150mm product specification ~200mm EH36 steel plates, i.e., do not changing alloying component(Ensure low-carbon-equivalent)And on the premise of the condition of delivery, buying is special The high-strength homogeneous steel plate of thick series.
The purpose of the present invention is not increase precious alloy additionally, still ensureing welded steel using low-carbon-equivalent chemical composition On the premise of performance, still take normalizing to produce, for the EH36 steel plates of bigger thickness, redesign Plate Production technique, it is ensured that The structural homogenity of the special heavy plate produced.
The content of the invention
The purpose of the present invention is the special thickness EH36 of 180~200mm that a kind of normalizing state delivery is provided for above-mentioned prior art The preparation method of steel plate.From the thick steel ingot of >=900mm, steel ingot rolls into middle base, the thickness and finished steel of middle base through cogging Compression ratio be 2.0~2.5, middle base is rolled to finished product thickness through controlled rolling again, using the mode of production of steel ingot cogging+controlled rolling, phase When in having carried out austenite recrystallization twice to blank, it is ensured that final big thickness steel plate end properties is in a thickness direction Homogeneity, has specifically ensured that the performance at 1/2 thickness.The present invention is from blank to finished steel, compression ratio >=4.5, and this method is real Show the standard analysis suitable for general thickness EH36 to stand good the present invention.
The present invention the used technical scheme that solves the above problems is:A kind of 180~200mm thickness EH36 of normalizing state delivery Steel plate, the chemical composition of the steel plate is to be based on standard GB/T 712 or classification society rule, substitutes micro element Ti to prevent using Al Ti and the compound precipitation of other elements such as Nb, O, N;Addition element V expands hydrogen control in favor of special heavy plate, chemical by weight percentage Composition is:C:0.11~0.18%, Si:0.15~0.50%, Mn:1.30~1.60%, P:≤ 0.0070%, S:≤ 0.0030%, Nb:0.010~0.050%, V:0.030~0.080%, Al:0.050~0.070%, Ni:0.10~0.40%, Cr:0.10~ 0.20%, surplus is Fe and inevitable impurity element.
Preferably, the chemical composition of steel plate is C by weight percentage:0.17%, Si:0.25%, Mn:1.55%, P:≤ 0.0060%, S:≤ 0.0020%, Nb:0.035%, V:0.065%, Al:0.060%, Ni:0.30%, Cr:0.15%, surplus is Fe And inevitable impurity element.
Obvious gradient structure is not present in thickness direction in steel plate, and steel plate is organized as a small amount of shellfish based on ferritic-pearlitic Mixing tissue supplemented by family name's body, average grain size is 8~12 μm.Yield strength transverse tensile property is 380~430MPa, is resisted 550~600MPa of tensile strength, elongation percentage >=21%, steel plate is at 1/4 thickness, -40 DEG C of notched bar impact strength >=60 at 1/2 thickness J。
The design principle of composition of steel of the present invention is:
C addition can increase the quenching degree of steel, particularly Heavy Plate Production, can significantly improve the intensity of normalized steel, But C content is excessively unfavorable for the ultralow temperature impact performance of steel, low temperature strain-aging performance, welding performance and corrosion resisting property, So carbon content control controls for low-carbon in the present invention, between 0.11~0.18%.
Si is mainly used in deoxidation, though to determine its addition according to different smelting modes, to obtain good steel Plate performance, it is necessary to more than 0.15%, if but center portion segregation and destruction welding performance can be caused again more than more than 0.50%, so Regulation is limited to 0.50% thereon.
Mn has in the steel postpones effect of the austenite to ferritic transformation, to fining ferrite, improve intensity and Toughness is favourable.When the content of manganese is relatively low, above-mentioned effect is not notable, and armor plate strength and toughness are relatively low etc..It is too high, company can be caused again Strand segregation, poor toughness and solderability reduction, while classification society rule requires that the manganese content upper limit is 1.60% etc., therefore in the present invention Comprehensive in view of alloy adds, and regulation manganese content addition is in the range of 1.30~1.60%.
Nb solute effect of dragging and Nb (C, N) suppresses deformed austeaite again to the pinning effect of austenite grain boundary Crystallization, expands between the non-recrystallization zone of austenite, reduces special heavy plate production time of staying temperature.And precipitation is formed in cooling or tempering Thing, so that intensity and toughness are improved, can also improve the corrosion resisting property of steel.Addition be less than 0.020% when effect not Toughness is reduced when substantially, more than 0.050%, causes continuous casting billet to produce face crack.Therefore, present invention provide that content of niobium should be between In the range of 0.020~0.050%.
V is the excellent deoxidier of steel, is effective crystal grain thinning element, improves the intensity and toughness of steel.In normalized steel, V belongs to precipitation strength element, while be beneficial to slab expands hydrogen in annealing process.Toughness is reduced when addition is more than 0.080%, The center segregation of slab is notable.Therefore, present invention provide that content of niobium should be in the range of 0.030~0.080%.
It is the addition that the Ti for substituting micro element is refined using Al for fixing the nitrogen in steel that Al, which is, with prevent Ti with Other elements such as Nb, O, N are compound to be separated out, and is formed hard Large Inclusions of prismatic etc., is caused impact property unstable.Meanwhile, Al content is too high, is easily caused the blocking of crystallizer rising head, the formation of the large-scale oxide containing Al.In the present invention, regulation aluminium content is situated between In 0.050~0.070%.
Ni is the element for improving steel hardenability, is also the most frequently used element for the low-temperature flexibility for effectively improving steel.In addition, and steel Middle remaining Cr, P compound action, it will help the corrosion resistance of raising steel, but classification society rule's set upper limit 0.40%, in order to Without departing from classification society rule's regulation.Therefore in the present invention, regulation nickel content is between 0.15~0.40%.
Cr is the element for improving steel hardenability, can suppress the formation of polygonal ferrite and pearlite, promotes low temperature group The transformation of bainite or martensite is knitted, the intensity of steel is improved.But Cr too high levels will influence the toughness of steel, and cause Temper brittleness Property, classification society rule requires to be no more than 0.20%.Therefore chromium content control is 0.10~0.20% in the present invention.
Though P can improve corrosion resistance, low-temperature flexibility can be reduced and solderability is hindered, be unsuitable, this hair to structural steel It is bright because be ingot smelting, provide its control below 0.0070%.
S formation MnS field trashes, also result in center segregation, also have harmful effect to corrosion resistance, present invention provide that in its control System is below 0.0030%.
The preparation method of 180~200mm thickness EH36 steel plates of above-mentioned normalizing state delivery, including following process,
(1)Smelting process:
From high duty pig iron and steel scrap as raw materials for metallurgy, selection high-quality steel-making supplementary material, raw material successively through electric furnace smelting, LF refining, VD refinings, molding, five big harmful residual control of element:S≤0.0030%, P≤0.0070%, H≤0.00015%, O ≤ 0.0015%, N≤0.0050%;Ensure the total rank of field trash A, B, C, D class in steel plate finished product below 3.0 grades;
In order to suppress steel ingot internal defect, segregation, the molten steel casting degree of superheat is 25~40 DEG C, and casting cycle is using whole argon Gas shielded, is cast into >=thick 900mm cast slab;
After steel ingot is raised one's hat, the slow cooling expansion hydrogen that burial pit is carried out 48~72 hours is entered with mould;
Steel ingot feeder head is cut off after carrying out removing surface, cleaning after slow cooling;
(2)Steel ingot cogging technique:
Steel ingot is heated to 1230~1260 DEG C in soaking pit, steel ingot soaking time is 10~15min/cm, after coming out of the stove Through high-pressure water descaling, then split rolling method is into middle base, the thickness of middle base meet its compression ratio with finished product thickness between 2.0~2.5;The offline covering slow cooling of middle base after cogging more than 48 hours;
(3)Rolling mill practice:
Middle base is heated to 1180~1250 DEG C, the middle base heat time is 11~14min/cm, makes the alloy in steel The abundant solid solution of element is to ensure the composition of final products and the uniformity of performance.Steel billet come out of the stove after through high-pressure water descaling, it is and laggard Row roughing+finish rolling two-stage control rolling:The start rolling temperature of roughing is 1050~1100 DEG C, using heavy reduction rolling, rolling When without turning steel rolling, full axial rolling is kept, to ensure that each passage carries out setting reduction ratio by rolling maximum capacity as far as possible.Slightly The road single pass reduction ratios of Zha Hou tri- are 10~15%;The start rolling temperature of finish rolling is 850~920 DEG C, is rolled to finished product thickness, finish rolling is complete Accelerate to cool down into rear progress ACC, cooling red temperature is 630~700 DEG C;
(4)Normalizing heat treatment technique:
Steel plate makees normalizing heat treatment after rolling, and normalizing temperature is 880~920 DEG C, and soaking time is 1.5~2.2min/mm. Specifically, steel plate normalizing is heat-treated using continuous oven, the normalizing temperature of continuous oven is 880~920 DEG C, enters stove to the time of coming out of the stove For 1.6~2.2min/mm;Or steel plate normalizing is heat-treated using soaking pit, soaking pit normalizing temperature is 880-920 DEG C, is protected The warm time is 1.5~2.1min/mm.
The present invention has following features:
The present invention is to be based on carbon manganese steel composition design principle, not the extra increase precious alloy such as Ni, Cu, save alloy into This.Carbon equivalent is low, and common EH36 welding material, welding procedure can be still matched during welding.
The smelting molten steel method of the application has the advantages that residual elements are low, Cleanliness of Molten Steel is high, is applicable to other high The production of the special thick steel grade of standard.
The inventive method, is produced by steel ingot cogging+controlled rolling, is related in the operation of rolling at austenite recrystallization heat twice Reason so that the original austenite grains in material are more uniform tiny.Cogging heating-up temperature has reached 1230-1260 DEG C, effectively Steel ingot center portion segregation is improved, this is to ensure final special heavy plate finished product tissue, the important prerequisite of performance uniformity.Middle base heating Temperature is 1180-1250 DEG C, is conducive to austenite recrystallization, meanwhile, when the relation reheating temperature of middle base is unlike steel ingot cogging Heating-up temperature is high like that, it is therefore an objective to ensure to be unlikely to roughening after austenite recrystallization.
Steel billet after rolling is handled by normalizing process, is not changed the process program that classification society rule provides to require, is used Family is more easily accepted by.When also overcoming the PROCESS FOR TREATMENT special heavy plate such as the quenched of prior art, NAC on through-thickness tissue gradient compared with Greatly, the shortcoming of poor performance etc..
The special thickness EH36 ship steels produced under the conditions of the present invention have good obdurability, and steel plate is not present bright in thickness direction Aobvious gradient structure, the main mixing tissue based on ferritic-pearlitic, supplemented by a small amount of bainite of steel plate tissue.Micro- group Fine uniform is knitted, is 8-12 μm with shot measurement steel plate average grain size is cut.
Brief description of the drawings
Fig. 1 is the metallographic structure at the thickness of 1 light plate of the embodiment of the present invention 1/4, is a small amount of shellfish based on ferritic-pearlitic Line and staff control supplemented by family name's body tissue;
Fig. 2 is the metallographic structure at the thickness of 1 light plate of the embodiment of the present invention 1/2, is a small amount of shellfish based on ferritic-pearlitic Line and staff control supplemented by family name's body tissue.
Embodiment
The present invention is described in further detail below in conjunction with accompanying drawing embodiment.
The preparation method of special thickness EH36 steel:
(1)From high-quality steel scrap as raw materials for metallurgy, supplementary material is made steel using high-quality, two stoves are smelted, per 50 tons of stove.Molten steel Refined successively through electric furnace smelting, LF refining, VD, stable state is cast into 4 steel ingots, and every 25 tons of steel ingot, the present invention uses therein 3 steel ingots are respectively as embodiment 1 to 3.Steel ingot section is more than 900mm, to ensure that the compression ratio with final products is more than 4.5. Control the big harmful residual element of molten steel five:S≤0.0030%, P is that 0.0070%, H is that 0.00012%, O is that 0.0010%, N is 0.004%.Fully floated with controlling steel ingot internal defect, requirement of the segregation to the degree of superheat, in 25-40 in view of field trash to be allowed Cast in the case of DEG C degree of superheat, casting is cast into >=thick 900mm cast slab using whole argon gas protection.After steel ingot is raised one's hat, Band mould enters burial pit and carries out the expansion hydrogen of slow cooling in 48-72 hours.Steel ingot is without band Wen Qing in ingot conditioning surface after slow cooling, the present embodiment Reason, Steel ingot feeder head is cut off after cleaning.The smelting component of each embodiment correspondence steel ingot is as shown in table 1.
The chemical composition of the embodiment ocean engineering EH36 steel plates of table 1(wt%)
Embodiment C Si Mn P S Ni Cr Al V Nb
Embodiment 1,2 0.13 0.25 1.55 0.007 0.0020 0.35 0.15 0.055 0.065 0.035
Embodiment 3 0.14 0.30 1.45 0.007 0.0015 0.30 0.10 0.065 0.070 0.044
(2)By after cleaning >=900mm steel ingots are heated to 1230-1260 DEG C in soaking pit, the Heating Steel Ingots time is 13min/cm, through high-pressure water descaling after coming out of the stove, then split rolling method is into middle base, it is ensured that the pressure of workpiece thickness and finished product thickness Ratio contract in 2.0-2.5.Base is offline in the middle of gained after cogging, covering slow cooling 48 hours or so, is carried out with the middle base of other steel grades Upper berth lower cover.
Middle base is sent into walking beam furnace, 1180-1250 DEG C is heated to, the middle base heat time is 11-14min/ Cm, makes the abundant solid solution of the alloying element in steel, it is ensured that the composition of final products and the uniformity of performance.Steel billet come out of the stove after through high pressure Then water de-scaling carries out roughing+finish rolling two-stage control rolling:The start rolling temperature of roughing is between 1050-1100 DEG C, using big pressure Lower amount rolling, without turning steel rolling during rolling, keeps full axial rolling, it is ensured that each passage is carried out by rolling maximum capacity as much as possible Set reduction ratio.The single pass reduction ratio in the roads of roughing Hou tri- is 10-15%;Finish rolling start rolling temperature is between 850-920 DEG C, finish rolling To finished product thickness, ACC units are sent to carry out acceleration cooling, cooling red temperature is 630-700 DEG C.
(3)Normalized treatment:Normalized treatment is carried out from soaking pit, normalizing temperature control is 890-910 DEG C, and soaking time is 2.0min/mm±5min。
Embodiment 1 to 3 is 180-200mm special thickness EH36 plates, and the total rank control of field trash A, B, C, D class is 2.0.It is just special For slab, the performance of the uniformity direct relation steel of steel plate in a thickness direction, uniform tissue is that steel plate is normally used And the safety assurance being on active service.
It is of the invention that performance at spy thickness EH36 plates 1/2 is detected, table 2, from the point of view of steel plate stretching performance, steel plate surrender Intensity transverse tensile property is between 380~430MPa, and tensile strength is between 550~600MPa, and elongation percentage is moderate, More than GB712 requirements.Tensile property is slightly below at 1/4 thickness at the thickness of steel plate 1/2, but difference is little.Each embodiment steel plate Low-temperature impact toughness as shown in table 3, the J of -40 DEG C of notched bar impact strength at steel plate thickness 1/4, at 1/2 >=60.
The various embodiments of the present invention tensile property of table 2
The various embodiments of the present invention impact property of table 3
In addition to the implementation, present invention additionally comprises have other embodiment, all use equivalent transformation or equivalent replacements The technical scheme that mode is formed, all should fall within the scope of the hereto appended claims.

Claims (5)

1. a kind of 180~200mm thickness EH36 steel plates of normalizing state delivery, it is characterised in that:The chemical composition of the steel plate is to be based on Standard GB/T 712 or classification society rule, substitute micro element Ti to prevent Ti and the compound precipitation of Nb, O, N using Al;Addition element V expands hydrogen control in favor of special heavy plate, and chemical composition is by weight percentage:C:0.11~0.18%, Si:0.15~0.50%, Mn:1.30~1.60%, P:≤ 0.0070%, S:≤ 0.0030%, Nb:0.010~0.050%, V:0.030~0.080%, Al: 0.050~0.070%, Ni:0.10~0.40%, Cr:0.10~0.20%, surplus is Fe and inevitable impurity element;
The preparation method of steel plate includes following process,
(1)Smelting process
From high duty pig iron and steel scrap as raw materials for metallurgy, selection high-quality steel-making supplementary material, raw material is smart through electric furnace smelting, LF successively Refining, VD refinings, molding, five big harmful residual control of element:S≤0.0030%, P≤0.0060%, H≤0.00015%, O≤ 0.0015%, N≤0.0050%;Ensure the total rank of field trash A, B, C, D class in steel plate finished product below 3.0 grades;
In order to suppress steel ingot internal defect, segregation, the molten steel casting degree of superheat is 25~40 DEG C, and casting cycle is protected using whole argon gas Shield, is cast into >=thick 900mm cast slab;
After steel ingot is raised one's hat, the slow cooling expansion hydrogen that burial pit is carried out 48~72 hours is entered with mould;
Steel ingot feeder head is cut off after carrying out removing surface, cleaning after slow cooling;
(2)Steel ingot cogging technique:
Steel ingot is heated to 1230~1260 DEG C in soaking pit, steel ingot soaking time is 10~15min/cm, through height after coming out of the stove Press water de-scaling, then split rolling method is into middle base, the thickness of middle base meet its compression ratio with finished product thickness between 2.0~ 2.5;The offline covering slow cooling of middle base after cogging more than 48 hours;
(3)Rolling mill practice:
Middle base is heated to 1180~1250 DEG C, the middle base heat time is 11~14min/cm, steel billet come out of the stove after through high pressure Water de-scaling, then carries out roughing+finish rolling two-stage control rolling:The start rolling temperature of roughing is 1050~1100 DEG C, using big pressure Lower amount rolling, without turning steel rolling during rolling, keeps full axial rolling, and three road single pass reduction ratios are 10~15% after roughing;Finish rolling Start rolling temperature be 850~920 DEG C, be rolled to finished product thickness, after the completion of finish rolling carry out ACC accelerate cooling, cooling red temperature be 630~700 DEG C;
(4)Normalizing heat treatment technique:
Steel plate makees normalizing heat treatment after rolling, and normalizing temperature is 880~920 DEG C, and soaking time is 1.5~2.2min/mm.
2. 180~200mm thickness EH36 steel plates of normalizing state delivery according to claim 1, it is characterised in that:The steel plate Chemical composition is C by weight percentage:0.17%, Si:0.25%, Mn:1.55%, P:≤ 0.0060%, S:≤ 0.0020%, Nb: 0.035%, V:0.065%, Al:0.060%, Ni:0.30%, Cr:0.15%, surplus is Fe and inevitable impurity element.
3. 180~200mm thickness EH36 steel plates of normalizing state delivery according to claim 1 or 2, it is characterised in that:Steel plate Obvious gradient structure is not present in thickness direction, and steel plate is organized as mixed supplemented by a small amount of bainite based on ferritic-pearlitic And tissue, average grain size is 8~12 μm.
4. 180~200mm thickness EH36 steel plates of normalizing state delivery according to claim 1 or 2, it is characterised in that:Surrender Intensity transverse tensile property be 380~430MPa, 550~600MPa of tensile strength, elongation percentage >=21%, steel plate is in 1/4 thickness Place, the J of -40 DEG C of notched bar impact strengths at 1/2 thickness >=60.
5. the preparation method of 180~200mm thickness EH36 steel plates of normalizing state delivery according to claim 1, its feature exists In:Steel plate normalizing is heat-treated using continuous oven, the normalizing temperature of continuous oven is 880~920 DEG C, entering stove to the time of coming out of the stove is 1.6~2.2min/mm;Or steel plate normalizing is heat-treated using soaking pit, soaking pit normalizing temperature is 880-920 DEG C, insulation Time is 1.5~2.1min/mm.
CN201610374131.5A 2016-05-31 2016-05-31 A kind of 180~200mm thickness EH36 steel plates of normalizing state delivery and preparation method thereof CN105839003B (en)

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