CN107385329B - A kind of big thickness Q500GJE high-strength building structural steel plate and its manufacturing method - Google Patents

Abstract

The present invention relates to a kind of big thickness Q500GJE high-strength building structural steel plates, the chemical component of the steel plate is by mass percentage, C:0.07~0.14%, Si:0.20~0.50%, Mn:1.2~1.60%, P :≤0.008%, S :≤0.005%, Cr:0.10~0.30%, Mo :≤0.30%, Ni:0.20~0.30%, Cu :≤0.30%, Al:0.02~0.04%, Nb:0.020~0.060%, Ti:0.01~0.02%, V+Nb+Ti≤0.22%, N :≤0.007% and inevitable impurity element, carbon equivalent is 0.36~0.46%.Process flow: molten iron pretreatment, converter smelting, the refining of LF furnace, the refining of RH furnace, casting blank of continuous casting machine, blank heating, milling train controlled rolling, Acc cooling and finishing.The performance of the application building structure steel product is uniform, and comprehensive performance is good；It is with short production cycle, production cost is low.

Description

A kind of big thickness Q500GJE high-strength building structural steel plate and its manufacturing method

Technical field

The present invention relates to special steel metallurgical technology field, especially a kind of big thickness Q500GJE high-strength building structural steel Plate and its manufacturing method.

Background technique

The large sizes such as skyscraper, super high-rise building, large span stadiums, airport, conference and exhibition center and steel-structure factory building The structural steel GJ of architectural engineering has strict requirements, is to be different from existing for the special steel grade of other purposes steel grades, building Industry is also especially specific and clearly demarcated to the classification of building structural steel, and the different trades mark has different purposes.

" steel plate for building structure " (GB/T 19879~2015) that in November, 2016 implements, than GB/T 19879~2005 Version has newly increased the multiple high-intensitive trade mark such as Q500GJ, Q550GJ etc..This illustrates that the steel plate for tall building of China in recent years is answered With more and more, in following not far skyscraper, super high-rise building, large span stadiums, airport, conference and exhibition center and steel In terms of the large-scale construction engineerings such as structure workshop, only high-intensitive such as 420MPa, 460MPa grades of steel plate for building is had been unable to meet Building trade demand for development.The appearance of the standard will be helpful to the building structure for promoting Corporation R & D to be higher than Q460GJ or more the trade mark Use steel plate.

In the prior art, the Q500 steel plate of correlation intensity can only just have in mechanical equipment steel at present, but mechanical equipment The requirement of building trade is far not achieved again with steel,Such as yield tensile ratio, ballistic work, shock resistanceAll it cannot be guaranteed.

A kind of invention " quenched high intensity Q500D super-thick steel plate production method " of notification number CN103556075B is to use 300mm continuous casting billet produces 100~120mm special heavy plate, with slab rolling+Tempering and Quenching.It is large-scale that steel plate is applied to mine, harbour The production of equipment, high production cost, the production cycle is long, and the condition of delivery is QT, limits the use of client.Notification number A kind of invention " production method of quenched high intensity Q500E super-thick steel plate " of CN103556074B is using slab rolling+tune The production technology of matter heat treatment, produces Q500E super-thick steel plate, belongs to mine, harbour large scale equipment steel, and high production cost is raw It is long to produce the period, and the condition of delivery is QT, limits the use of client.

For the standard of GB/T 19879~2015 for building structural steel requirement, exploitation high intensity, low yield strength ratio, low temperature are tough Property excellent Q500GJ series in new product, simplify production technology, shorten the production cycle, reducing production cost is this field skill The Research Emphasis of art personnel.

The purpose of the application is the Q500GJD steel plate in earlier application (applicable environment temperature is~20 DEG C (containing) or more) On the basis of further develop Q500GJE steel plate (material), be suitable in environment temperature~40 DEG C (containing) it is used above.China east Most of north, northwest area are at for a long time in~20 DEG C to~40 DEG C (containing) environment temperatures, and invention Q500GJE product is should The construction industry development in area, reduction building cost will play positive effect.

Summary of the invention

The present invention uses 150mm~370mm continuous casting billet production 12~40mm thickness, the condition of delivery for TMCP(controlled rolling and controlled cooling) Structural steel Q500GJE for building, the thickness of steel plate meets the separate provision of GB/T 19879~2015: minimum, maximum gauge Specification, comprehensive performance on the basis of fully meeting the requirement of GB/T 19879~2015 and steel plate for tall building, Yield strength, the fluctuation range of tensile strength of product are small, and yield tensile ratio reaches≤0.8, and the performance of product is uniform, stablizes；Production Period is short, production cost is low.

The present invention solves the above problems used technical solution are as follows: a kind of big thickness Q500GJE high-strength building structure Chemical component with steel plate, the steel plate is C:0.07~0.14% by mass percentage, Si:0.20~0.50%, Mn:1.2~ 1.60%, P :≤0.008%, S :≤0.005%, Cr:0.10~0.30%, Mo :≤0.30%, Ni:0.20~0.30%, Cu :≤ 0.30%, Al:0.02~0.04%, Nb:0.020~0.060%, Ti:0.01~0.02%, V+Nb+Ti≤0.22%, N :≤ 0.007% inevitable impurity element, carbon equivalent are 0.36~0.46%.

Above-mentioned steel plate is that GB/T 19879~2015 is respectively provided most with a thickness of 12~40mm(12 mm, 40 mm Small, maximum gauge specification), the condition of delivery is the Q500GJE steel plate for building structure of TMCP, and 530~570MPa of yield strength resists 660~710MPa of tensile strength, elongation >=20%；Yield tensile ratio≤0.80(and standard is≤0.85), -40 DEG C of V-type ballistic work >=15 0J.Its comprehensive performance is able to satisfy the customer requirement of steel plate for tall building completely.

The main function for the smelting ingredient each element that the present invention designs:

C:C element forms the solute element of interstitial solid solution in Fe, and solid solution strengthening effect is greater than other elements in Fe The middle solute element for forming displaced type solid solution.C in the tissue of steel in the form of cementite or pearlite in the presence of can generate very Big phase transformation strengthening, improves intensity；But reduce toughness；Therefore it is 0.12~0.17% that the present invention, which controls C content,.

Mn:Mn element forms the solute element of displaced type solid solution in Fe；Mn mainly passes through that " Mn of solid solution has relatively strong Solid solution strengthening effect, expand iron austenite region, Mn content increase the toughness of steel is had a significant impact " etc. number of mechanisms. Therefore, mentality of designing of the invention is centered around always on refinement crystal grain, is 1.10~1.60% by the control of Mn content.

S: in micro- low-alloy steel, the content of S, which improves, declines the plasticity of steel, toughness；It is therefore preferable that S content to the greatest extent may be used Can be low, it is too low to cause production cost surging.For this purpose, preferably S is 0.002~0.005%.

P: phosphorus is the harmful element in steel, and between 0.016~0.025%, phosphorus content height can be the phosphorus content of cut deal Tensile strength slightly improves, but plasticity and toughness decline, and steel becomes fragile, and is unfavorable for being cold worked and weld, and is easily segregated, therefore as far as possible Reduce the phosphorus content in steel.For this purpose, P content is controlled≤0.008% by the present invention.

Nb:Nb can prevent crystal grain from growing up when low-alloy steel heats；During the rolling process by strain inducing, Nb is precipitated Carbide precipitation on crystal boundary and dislocation, prevent ausforming recrystallize, reach refinement crystal grain；There is precipitation enhancement； The microscopic structure of steel can be improved, improve performance.

V:V is other than having Nb characteristic of elements, when the compound addition of Nb~V, intensity than individually plus Nb it is high.Austria can also be made Family name's body crystal grain further refines, and keeps ferrite crystal grain after cooling more tiny, is conducive to the improvement of toughness.

Ti: it is to strengthen solid N element.In compound humble steel alloy, N preferentially will form TiN with Ti.TiN prevents heating When AUSTENITE GRAIN COARSENING effect ratio Nb(CN) it is big；The TiN and VN being precipitated using high temperature prevent austenite recrystallization crystal grain thick Change.

Si:Si does not form carbide in steel.But its solid solubility in iron is larger, the significant reinforced ferrite of energy, Gu Molten strengthening effect is higher than Mn.But when Si higher, intensity increases, but toughness declines.Therefore it controls within the scope of its proper content.

Cr: it is medium carbide former.The Cr in ferrite is dissolved in, solution strengthening is generated, there is stronger quench Permeability improves the intensity of steel.But the welding performance that can excessively reduce the toughness of material while also reduce material is added.Therefore, Content control is 0.10~0.30%

Ni:Ni is non-carbide forming element.It reduces the C content of eutectoid point, increases the volume fraction of pearlite, has Conducive to raising intensity；The brittle transition temperature for advantageously reducing material simultaneously, improves the impact property of material.But Ni is unfavorable for giving birth to Produce cost;Therefore, Ni content control of the present invention is 0.10~0.30%.

Carbon in the tissue of steel in the form of cementite or pearlite in the presence of can generate very big phase transformation strengthening, improve strong Degree, it is especially more significant to tensile strength contribution, be conducive to the yield tensile ratio of product of the present invention；But it is unfavorable to the toughness of product.Cause This, when Design of Chemical Composition, should consider that product carbon equivalent is restricted, the comprehensive performance requirement cared for again and products thereof；So Carbon element content should not be added excessively high.The higher part in the part or yield tensile ratio that intensity lacks, can pass through and suitable micro- conjunction is added Gold element such as niobium, vanadium, aluminium, nickel etc., and the suitable rolling mill practice of selection；Chemical component and control technique are combined and can be played Precipitation strength, solution strengthening, refinement crystal grain, the inherent tissue for improving steel, reduce the brittle transition temperature of material；Power can be improved again Learn performance.Reach the target for being conducive to that yield tensile ratio is low, impact flexibility is good.

The manufacturing method of the big thickness Q500GJE high-strength building structural steel plate of the application, process flow: molten iron is located in advance Reason, converter smelting, the refining of LF furnace, the refining of RH furnace, casting blank of continuous casting machine, blank heating, milling train controlled rolling, Acc cooling and finishing.

(1) 150mm~370mm blank, continuous casting process major parameter: the degree of superheat 10 are produced using wide thickness plate continuous casting machine ~45 DEG C, 0.5~1.3m/min of casting machine pulling rate；Using dynamic secondary cooling technique, water proportion is 0.5~1.0L/kg；Solidification end is adopted With dynamic soft-reduction, electromagnetic agitation；Charge length is regular by the assembly of change release plate size, by blank scale；Under blank The slow cooling of line heap 24 hours or more；The blank of finishing qualification is sent into mill by production plan.

(2) blank heating: the preheating section temperature of heating furnace: 600~900 DEG C, heating one Duan Wendu: 1000~1180 DEG C, Heat two sections of temperature: 1200~1240 DEG C, soaking section temperature: 1160~1220 DEG C；Heating total time >=10 × H minutes, H is base Expect thickness, unit: cm；For the homogeneous heating for ensuring blank, blank each section should at the uniform velocity stepping in furnace.

(3) after blank is come out of the stove, removing iron scale is removed using thick descaling mill and pickle line processor；Thick de-scaling includes the water of smart de-scaling Pressure >=20MPa.

(4) rolling divides the two-stage: roughing and finish rolling,

The controlled rolling of roughing: roughing includes the controlled rolling of austenite recrystallization area and austenite Unhydrated cement controlled rolling again, slightly Roll start rolling temperature >=980 DEG C, in the controlled rolling of austenite recrystallization area, austenite recrystallization area makes with the increasing of pass deformation Crystal grain refinement after austenite recrystallization；To avoid especially big crystal grain from occurring, it should ensure that reduction in pass reaches certain in high-temperature region Amount, at least 2 passages are in the case where mill capacity allows, using heavy reduction, drafts >=38mm or reduction ratio >=15%；Ovshinsky In body Unhydrated cement controlled rolling: use heavy reduction, steel plate is rolled to temperature thickness by total reduction >=40%, to temperature thickness >= 50mm, plastic deformation elongate austenite grain, and the carbon nitridation of the microalloy elements such as Zona transformans and Nb, V, Ti is formed in crystal grain Ferrite preferential nucleation sites when the strain rust hair precipitating of object, deformed austenite crystal boundary are austenites to ferritic transformation；To The ferrite of crystal grain refinement is obtained, intensity improves, and brittle transition temperature declines (i.e. toughness raising).

The controlled rolling of finish rolling: entering austenite after band temperature and ferrite two-phase region rolls, and 820~900 DEG C of start rolling temperature, The pressure of certain passage is carried out in this two-phase region, deformation makes austenite grain continue to elongate in this temperature range, in its crystalline substance Intragranular portion, which is formed, deforms new glide band；And new ferrite nucleus is formed at these positions, and ferrite is first precipitated.Through deforming Afterwards, make to form a large amount of dislocations inside ferrite crystal grain, and form substructure (ferrite subgrain) in high temperature by these dislocations.Asia knot Structure improves intensity, and brittle transition temperature reduces.For the comprehensive performance for ensuring finished steel plate, its crystal grain should be refined；For this purpose, last Three accumulative reduction ratio >=28%, finishing temperature >=780 DEG C, preferably 780~830 DEG C.

(5) to ensure that the deformed austenite crystal grain after controlled rolling and the ferrite crystal grain after phase transformation are grown up, reach raising Intensity, the purpose for not damaging toughness send water in Acc cooling equipment cooling, 5~18 DEG C/s of cooling rate after the completion of rolling；It is cold eventually 580~730 DEG C of temperature, the grain size of metallographic structure at this time is up to 8.0 grades (containing) or more；Then direct sending heat rectification machine leveling, rolled piece heat Rectify temperature >=500 DEG C；Cold bed natural cooling is sent later；It is cooled to 300~400 DEG C of then offline heap slow cooling, heap slow cooling >=300 DEG C, Time >=24 hour.

(6) flaw detection, apparent mass are examined, physicochemical property is examined, are sheared or cut, storage.

Usual blank heating temperature is higher than 1200 DEG C, reaches rolling of coming out of the stove when technique requires in the soaking time of furnace.In height Warm area is rolled down to finished product thickness incessantly, therefore finishing temperature is higher, mostly in 950 DEG C or more (especially finished product thickness specifications In the steel plate of 20mm or more).Air-cooled, ferrite and pearlite organizational coarseness is used after rolling, performance is relatively low, toughness is poor.

For the steel plate comprehensive performance for obtaining high-intensitive, high tenacity, the application is using controlled rolling and controls cold (TMCP) technique.Controlled rolling Technique is divided into again: the controlled rolling of austenite recrystallization area, the controlled rolling of austenite Unhydrated cement, ferrite and pearlite (A+F) two-phase region Double raisings of intensity and toughness are realized in controlled rolling.In particular, uniformly tiny ferrite crystalline substance is likely to be obtained in Unhydrated cement rolling Grain, it is also possible to obtain the mixed crystal ferrite crystal grain of thickness unevenness.To avoid such unfavorable factor, in the timing of total deformation one, Under mill capacity permissive condition, percentage pass reduction is bigger, and Zona transformans is more easy to produce, and is easier in global tissue It is even.Therefore, it is the iron element alms bowl crystal grain for guaranteeing acquisition fine uniform, needs in Unhydrated cement using heavy reduction, total reduction >=40% is more satisfactory.

The GB/T 19879~2015 " steel plate for building structure " that in November, 2016 implements, than GB/T 19879~2005 editions Multiple the high-strength building trade mark such as Q500GJ, Q550GJ etc. are newly increased, there are no Q500GJE building occur on Vehicles Collected from Market Use steel sheet product.

The present invention is able to satisfy skyscraper, super high-rise building, large span stadiums, airport, conference and exhibition center and steel knot The high-strength building steel plate of MPa grades of the large-scale construction engineerings such as structure workshop demand 460 or more, can be used in -40 DEG C or more it is low Warm environment uses；And production cost is low, the manufacturing cycle is short.

The present invention uses 150mm~370mm thickness continuous casting material, and production 12~40 mm condition of delivery of thickness is TMCP Q500GJE steel plate, intensity is high, yield tensile ratio is low, low temperature performance well；It is with short production cycle, production cost is low.

Detailed description of the invention

Fig. 1 is the steel plate metallographic structure figure of the embodiment of the present invention 1.

Specific embodiment

Present invention is further described in detail with reference to embodiments.

Using Jing Guo desulfurization molten iron and high-quality steel scrap as raw material, converter bottom (top) blows smelting, whole Argon, and LF furnace is de- Oxygen, desulfurization, refining and the RH furnace degassing process for removing folder matter, adjusting component and temperature；Finally obtain the weight percent of molten steel To be basic element with Fe and including following elemental composition: C:0.07~0.14%, Si:0.20~0.50%, Mn:1.2~ 1.60%, P :≤0.008%, S :≤0.005%, Cr:0.10~0.30%, Mo :≤0.30%, Ni:0.20~0.30%, Cu :≤ 0.30%, Al:0.02~0.04%, Nb:0.020~0.060%, Ti:0.01~0.02%, V+Nb+Ti≤0.22%, N :≤ 0.007% and inevitable impurity element；The Q500GJE that carbon equivalent is 0.36~0.46%.

It is raw through wide thickness plate continuous casting machine constant temperature, constant speed and reasonable two cold technique, solidification end dynamic soft-reduction, electromagnetic agitation The continuous casting material of output 150mm~370mm.By the assembly rule of change release plate size, by blank scale；The offline heap of blank Slow cooling 24 hours or more.The blank of finishing qualification is sent into Rolling production by production plan.Heating process: the preheating section of heating furnace Temperature: 600~900 DEG C, two sections of one Duan Wendu: 1000~1180 DEG C of heating, heating temperature: 1200~1240 DEG C, soaking zone temperature Degree: 1160~1220 DEG C；Heat total time >=10 × H minutes (H is sotck thinkness, unit: cm).Heating to ensure blank is equal Even, blank each section should at the uniform velocity stepping in furnace.Blank uses thick descaling mill and pickle line processor except removing iron scale after coming out of the stove；Slightly remove Squama, smart de-scaling hydraulic pressure >=20MPa.

Obtain high-intensitive, high tenacity steel plate comprehensive performance, Ying Caiyong controlled rolling and cold (TMCP) technique of control

Rolling divides the two-stage: roughing controlled rolling and finishing rolling control rolling.

The controlled rolling of roughing: start rolling temperature >=980 DEG C, including the controlled rolling of austenite recrystallization area and austenite non-recrystallization Area's controlled rolling, at least 2 passages are in the case where mill capacity allows in austenite recrystallization area controlled rolling passage, using heavy reduction, pressure Amount >=38mm or reduction ratio >=15%；The total reduction of austenite Unhydrated cement controlled rolling is controlled >=40%, is rolled to gentle and kind Degree is not less than 50mm to temperature thickness.The controlled rolling of finish rolling: i.e. ferrite and pearlite (A+F) two-phase region controlled rolling, to Wen Houkai 820~900 DEG C of temperature are rolled, finishing temperature is 780~830 DEG C；Three accumulative reduction ratio >=28% after finish rolling.

Send boiled water in Acc cooling equipment cooling after the completion of rolling, 5~18 DEG C/s of cooling rate；Final cooling temperature 580~730 ℃；Then direct sending heat rectification machine leveling, rolled piece heat rectify temperature >=500 DEG C；Cold bed natural cooling is sent later；It is cooled to 300~400 DEG C Then offline heap slow cooling, heap slow cooling >=300 DEG C, time >=24 hour.Flaw detection, apparent mass are examined again, physicochemical property is examined It tests, shear or cuts, be put in storage.

Example 1: the present invention design smelting chemical ingredient provide Q500GJE thickness 370mm continuous casting material, smelting chemical at It is divided into C:0.10%, Si:0.3%, Mn:1.5%, P:0.0035%, S:0.003%, Cr:0.24%, Ni:0.23%, Al:0.035%, V+ Nb+Ti≤0.12%.Production rolling 40mm thickness steel plate example.With 370 × 2300 × 3200mm of continuous casting billet, mill product plate 40 × 2500 × L(length) mm.Blank cold charge enters heating furnace, the preheating section temperature of heating furnace: 750~900 DEG C, one Duan Wen of heating Degree: two sections of 1000~1150 DEG C, heating temperature: 1210~1230 DEG C, soaking section temperature: 1200~1220 DEG C；Heat total time 375 minutes.It is rolled through roughing, to temperature thickness 88mm；820 DEG C of finishing mill start rolling temperature, roll through finishing mill after temperature, finish to gauge temperature 815 DEG C of degree；Rolled piece direct sending enters watering in Acc equipment and accelerates to cool down after the completion of rolling, 12~13 DEG C/s of cooling rate, eventually cold temperature 590 DEG C of degree；Again through heat rectification machine leveling；Cold bed natural cooling is sent later, is cooled to offline heap slow cooling at 330 DEG C；Through 27 hours heaps The sampling of slow cooling rear hanging plate, physical and chemical inspection and quality inspection.Physicochemical property inspection result is shown in Table 1, metallographic structure (ferrite+pearly-lustre Body, 8.0 grades of grain size or more) such as Fig. 1.

Example 2: the present invention design smelting chemical ingredient provide Q500GJE thickness 150mm continuous casting material, smelting chemical at It is divided into C:0.09%, Si:0.33%, Mn:1.52%, P:0.004%, S:0.002%, Cr:0.22%, Ni:0.21%, Al:0.036%, V +Nb+Ti≤0.11%.Production rolling 12mm thickness steel plate example.With 150 × 2500 × 3300mm of continuous casting billet, mill product plate 12 × 2800 × L(length) mm.Blank cold charge enters heating furnace, and heating process is the same as example 1.It is rolled through roughing, to temperature thickness 50mm, to 900 DEG C of finishing mill start rolling temperature after temperature, then rolled through finish rolling, finishing temperature >=796 DEG C；Rolled piece direct sending enters Acc after the completion of rolling Watering accelerates to cool down in equipment, 6~7 DEG C/s of cooling rate, and 690~710 DEG C of final cooling temperature；Again through heat rectification machine leveling；Later Cold bed natural cooling is sent, offline heap slow cooling at 320 DEG C is cooled to；Sampling, physical and chemical inspection and quality inspection after heap slow cooling in 24 hours It tests.Physicochemical property inspection result is shown in Table 1.

The detection performance table 1 of Q500GJE

In addition to the implementation, all to use equivalent transformation or equivalent replacement the invention also includes there is an other embodiments The technical solution that mode is formed should all be fallen within the scope of the hereto appended claims.

Claims (4)

1. a kind of big thickness Q500GJE high-strength building structural steel plate, it is characterised in that: the chemical component of the steel plate presses matter Measuring percentages is C:0.07~0.14%, Si:0.20~0.50%, Mn:1.2~1.60%, P :≤0.008%, S :≤ 0.005%, Cr:0.10~0.30%, Mo :≤0.30%, Ni:0.20~0.30%, Cu :≤0.30%, Al:0.02~0.04%, Nb: 0.020~0.060%, Ti:0.01~0.02%, V+Nb+Ti≤0.22%, N :≤0.007% and inevitable impurity element, carbon Equivalent is 0.36~0.46%, yield tensile ratio≤0.80, -40 DEG C of V-type ballistic work >=150J, is organized as ferrite+pearlite, delivery State is TMCP, 8.0 grades of grain size or more；

TMCP technique is related to controlled rolling and cooling control after rolling, wherein rolling divides the two-stage: roughing and finish rolling,

The controlled rolling of roughing: roughing includes the controlled rolling of austenite recrystallization area and austenite Unhydrated cement controlled rolling again, and roughing is opened Temperature >=980 DEG C are rolled, at least 2 passages are in the case where mill capacity allows in the controlled rolling of austenite recrystallization area, using heavy reduction, Drafts >=38mm or reduction ratio >=15%, austenite Unhydrated cement controlled rolling: use heavy reduction, total reduction >=40%, Steel plate is rolled to temperature thickness, to temperature thickness >=50mm；

The controlled rolling of finish rolling: entering austenite after band temperature and ferrite two-phase region rolls, and 820~900 DEG C of start rolling temperature, finally Three accumulative reduction ratio >=28%, finishing temperature >=780 DEG C；

Cooling control after rolling is will to roll rear slab to send water in Acc cooling equipment cooling, controls 5~18 DEG C/s of cooling rate, control is cold eventually 580~730 DEG C of temperature.

2. big thickness Q500GJE high-strength building structural steel plate according to claim 1, it is characterised in that: steel plate is thick Spend 12~40mm, 530~570MPa of yield strength, 660~710MPa of tensile strength, elongation >=20%；Yield tensile ratio≤0.80 ,- 40 DEG C of V-type ballistic work >=150J.

3. the method for big thickness Q500GJE high-strength building structural steel plate, feature described in a kind of manufacturing claims 1 exist In: process flow: molten iron pretreatment, converter smelting, the refining of LF furnace, the refining of RH furnace, casting blank of continuous casting machine, blank heating, milling train control System rolling, Acc cooling and finishing,

(1) produce 150mm~370mm blank using wide thickness plate continuous casting machine, continuous casting process major parameter: the degree of superheat is 10~45 DEG C, 0.5~1.3m/min of casting machine pulling rate；Using dynamic secondary cooling technique, water proportion is 0.5~1.0L/kg；Solidification end is using dynamic State slighter compress, electromagnetic agitation；Charge length is regular by the assembly of change release plate size, by blank scale；The offline heap of blank Slow cooling 24 hours or more；The blank of finishing qualification is sent into mill by production plan；

(2) blank heating: the preheating section temperature of heating furnace: 600~900 DEG C, one Duan Wendu: 1000~1180 DEG C of heating, heating Two sections of temperature: 1200~1240 DEG C, soaking section temperature: 1160~1220 DEG C；Heating total time >=10 × H minutes, H are that blank is thick Degree, unit: cm；For the homogeneous heating for ensuring blank, blank each section should at the uniform velocity stepping in furnace；

(3) after blank is come out of the stove, removing iron scale is removed using thick descaling mill and pickle line processor；Thick de-scaling include smart de-scaling hydraulic pressure >= 20MPa；

(4) rolling divides the two-stage: roughing and finish rolling,

The controlled rolling of roughing: roughing includes the controlled rolling of austenite recrystallization area and austenite Unhydrated cement controlled rolling again, and roughing is opened Temperature >=980 DEG C are rolled, at least 2 passages are in the case where mill capacity allows in the controlled rolling of austenite recrystallization area, using heavy reduction, Drafts >=38mm or reduction ratio >=15%, austenite Unhydrated cement controlled rolling: use heavy reduction, total reduction >=40%, Plastic deformation elongates austenite grain, and the carbonitride of the microalloy elements such as Zona transformans and Nb, V, Ti is formed in crystal grain Strain-induced precipitating, steel plate is rolled to temperature thickness, to temperature thickness >=50mm；

The controlled rolling of finish rolling: entering austenite after band temperature and ferrite two-phase region rolls, and 820~900 DEG C of start rolling temperature, finally Three accumulative reduction ratio >=28%, finishing temperature >=780 DEG C；

(5) it is that the deformed austenite crystal grain after ensuring controlled rolling and the ferrite crystal grain after phase transformation are grown up, reaches raising intensity, Do not damage toughness rolling send water in Acc cooling equipment cooling after the completion, 5~18 DEG C/s of cooling rate；Final cooling temperature 580~730 DEG C, the grain size of metallographic structure at this time is up to 8.0 grades or more；Then direct sending heat rectification machine leveling, rolled piece heat rectify temperature >=500 DEG C；It After send cold bed natural cooling；It is cooled to 300~400 DEG C of then offline heap slow cooling, heap slow cooling >=300 DEG C, time >=24 hour；

(6) flaw detection, apparent mass are examined, physicochemical property is examined, are sheared or cut, storage.

4. the manufacturing method of big thickness Q500GJE high-strength building structural steel plate according to claim 3, feature Be: the finishing temperature of the finish rolling is 780~830 DEG C.