CN102409236A - Method for producing super-thick steel plate - Google Patents

Abstract

The invention discloses a method for producing a super-thick steel plate. The method comprises the following production process steps of: performing pretreatment on molten iron; making steel by using a convertor; performing external refining; continuously casting; heating; rolling; cooling in an accelerated way; normalizing; controlling a cold condition; finishing; inspecting performance; and performing ultrasonic flaw detection. In the method, a low-C high-Mn component system is utilized, and Ni and Cu alloy elements are added into the steel in combination with micro-alloying treatment of Nb, V and Ti. The steel comprises the following chemical components in percentage by weight: less than or equal to 0.12 percent of C, 0.20 to 0.40 percent of Si, 1.20 to 1.50 percent of Mn, less than or equal to 0.008 percent of P, less than or equal to 0.003 percent of S, 0.03 to 0.06 percent of AlT, less than or equal to 0.10 percent of Nb, Ti and V, less than or equal to 0.80 percent of Cu and Ni, less than or equal to 0.40 percent of Ceq and the balance of Fe and inevitable impurities. By the method, a continuous casting blank is used for producing high-performance Q345R steel plates with the thickness of 60 to 100mm, so that production cost is reduced, and the requirement of manufacturing containers with high parameter pressure is met; the low-C high-Mn component system is used for a component design, so that the requirement that the material Ceq is less than or equal to 0.40 percent is met; and the continuous casting blank is used for producing a high-performance Q345R super-thick plate, so that the method has a simple process, the process is easy to realize, and the plate can be produced by a common wide and thick plate factory.

Description

A kind of working method of super-thick steel plate

Affiliated technical field

The invention belongs to the working method of smelting iron and steel technology, particularly a kind of super-thick steel plate.

Background technology

Special heavy plate is meant the steel plate of thickness >=60mm.The working method that prior art adopts is concluded mainly and is: static ingot and electroslag remelting steel ingot method, continuously cast bloom slab method, the compound strand method of welding, vertical continuous caster are produced the special heavy plate method.

Development along with the Wide and Thick Slab production technology; Use the special heavy plate technology of 260～300mm slab production, 60～100mm very universal; But the intensity that is the assurance special heavy plate in common production technology is when adopting raising C, Mn content; In steel, add microalloy element Nb, V, Ti, separate out and cool off through mutagenesis in crystal grain thinning, the operation of rolling and separate out C (N) M and improve armor plate strength, production has produced influence to special heavy plate thus:

For the special heavy plate that hot-rolled state is delivered goods, adopt the low high Mn composition of C system, add Nb, the processing of Ti microalloying, and be aided with TMCP technology rolling technology, can produce Ceq greater than the serial special heavy plate of 0.36% Q345; Special heavy plate for as-normalized condition delivery adopts the high Mn composition of high C system, adds Nb, V, Ti crystal grain thinning, increases separating out of C (N) M, also can produce Q345 series special heavy plate, but the Ceq of this steel is greater than 0.41%; For the special heavy plate Q34R steel plate of as-normalized condition delivery, all be to adopt steel ingot rolling in the world, the technology of this respect is all ripe, but complex manufacturing, production cost are high, and general Wide and Thick Slab factory can not produce.

One Chinese patent application 201010160508.X discloses " low-carbon equivalent weight high-strength thick steel plate and method of manufacture that a kind of low-temperature flexibility is excellent "; Chemical component weight per-cent in the steel plate meets carbon equivalent Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (N1+Cu)/15≤0.40%; Change into and added Nb, V microalloy element in the branch, utilize controlled rolling to improve armor plate strength.Rolling technology is: 1200～1240 ℃ of thickness 220～260mm continuous blank heating temperatures, soaking time 240～270min, tapping temperature: 1180～1220 ℃; Adopt the controlled rolling of two stages, roll the back and adopt the laminar flow cooling, roll off the production line 400～450 ℃ of temperature of 625～725 ℃ of final cooling temperatures, 5～10 ℃/s of rate of cooling, high temperature.The weak point that this invention exists is to adopt TMCP explained hereafter 45～70mm steel plate; Can only satisfy the general steelwork of impact of collision toughness reguirements and make needs; Intensity is low after the steel plate normalizing treatment, can not be used for requirement normalizing, 1/2 and 1/4 thickness transverse impact toughness, Z to the production with special heavy plate of the pressurized vessel of performance.

The manufacturing of high-parameters pressurized vessel with the Q345R special heavy plate (60～100mm) delivery technical qualification in; Except that the standard-required that satisfies GB/T713, the steel plate dilivery state is normalizing, guarantee steel plate 1/4 and 1/2 thickness-20 ℃ ballistic work (laterally) greater than 100J, 1 grade of UT is qualified one by one, thickness directional properties reaches the Z35 requirement, high temperature tensile properties (200 ℃) satisfies standard-required, Ceq less than 0.40%.To above-mentioned technical requirements, existing at present manufacturing enterprise does not also have the production report and the production actual achievement of continuously cast bloom stocking, has many defectives in the production:

A.Ceq delivers goods less than 0.40% Q345R special heavy plate as-normalized condition, and intensity is low can not to satisfy standard-required;

B. continuously cast bloom is difficult to satisfy the requirement greater than 100J of steel plate 1/4 and 1/2 thickness-20 ℃ ballistic work (laterally);

C. rolling technology is difficult to satisfy thickness directional properties and reaches the Z35 requirement.

Summary of the invention

The working method that the purpose of this invention is to provide a kind of super-thick steel plate: adopt 300mm thickness continuously cast bloom rolling, simplify production process, reduce production costs; The employing microalloying is handled, and utilizes separating out of ε-Cu to produce low-carbon-equivalent (Ceq≤0.40%) high-performance pressurized vessel with 60～100mm steel plate, satisfies the needs that the high-parameters pressurized vessel is made.

Technical scheme of the present invention:

The production process route of steel: hot metal pretreatment → converter steelmaking → external refining → continuous casting → heating → rolling → acceleration cooling → normalizing → control is cold → finishing.

The low high Mn composition of C system is adopted in the composition design; In steel, add Nb, V, Ti microalloy element, be aided with high temperature and depress rolling at a slow speed, TMCP rolling technology greatly, utilize the mutagenesis of the operation of rolling to separate out and roll postprecipitation and separate out and improve the steel plate obdurability; In steel, add Ni and improve steel plate 1/4 and the horizontal low-temperature impact toughness of 1/2 thickness; In steel, add Cu, utilize separating out of ε-Cu behind solid solution and the special cooling control technology of normalizing Cu, improve the intensity of steel plate.

The composition design of steel: adopt the low high Mn composition of C system, in steel, add Ni, Cu alloying element, be aided with Nb, V, the processing of Ti microalloying.The chemical constitution percentage composition of steel is: C≤0.12, and Si=0.20～0.40, Mn=1.20～1.50, P≤0.008, S≤0.003, AlT=0.03～0.06, Nb+ Ti+ V≤0.10, Cu+Ni≤0.80, Ceq≤0.40, surplus is Fe and unavoidable impurities.

Each technology concrete steps and processing parameter are:

(1) converter steelmaking: the converter Intake Quantity is controlled by 120～135t, tapping carbon 0.08～0.10%, 1610～1670 ℃ of tapping temperatures; Alloy should begin to add when tapping to 1/3 left and right sides; Add during to 2/3 left and right sides, in ladle, add 400kg above top slag charge or refining slag in the tapping process, feed the Al line behind the stove and must not be less than 200m; Require Al >=0.020% in the molten steel, must keep omnidistance Argon state.

(2) external refining: molten steel is at LF stove conduction time >=18min, total argon blowing time >=35 minutes, white slag hold-time >=10 ~ 12min; The LF stove is fed Si-Ca line or Ca-Fe line >=500m, and the line feeding of LF stove can not mended before VD (RH) stove evacuation completely and fed, and molten steel carries out the operation of soft blow argon before going out LF; The soft blow argon time should be greater than 5min; Add an amount of Ti-Fe according to the molten steel amount before the departures, guarantee that Ti content is controlled at the internal control scope, departures C is by 0.110% control.

The control of VD (RH) stove: confirm VD (RH) the stove treatment time according to the molten steel temperature drop rule, require VD (RH) stove at total argon blowing time>=30min that stands, vacuumize, below the vacuum tightness 0.5tor, the hold-time is not less than 15min; The soft blow argon is greater than 10min, the molten steel hydrogen that goes out to stand firm, H≤1.0ppm, appear on the stage 1565～1575 ℃ of temperature of departures.

(3) continuous casting control: big bag adopts long sleeve pipe to add the cast of argon gas seal protection, and the tundish pouring molten steel normal level of liquid degree of depth >=1m, middle bag add insulating covering agent protection cast.The mouth of a river adds sealing-ring protection cast under adopting, and immerses the molten steel in mold degree of depth >=120mm.5～10 ℃ of molten steel overheats, 1524 ~ 1534 ℃ of middle bag representative temperatures.Roll off the production line stacking slow cooling 24～72 hours of 300mm strand.

(4) heating: 1200～1280 ℃ of slab heating, heat-up time 10～15min/cm, soaking time is greater than 60min, the upper surface temperature is higher than 10 ~ 20 ℃ of lower surfaces, come out of the stove heart portion temperature >=1200 ℃ of slab.

(5) rolling:

stage start rolling temperature>=1050 ℃, 950～980 ℃ of finishing temperatures.It is rolling at a slow speed that steel plate rolling requires roughing to adopt high temperature to depress greatly, and the roughing roll speed is reduced to 1.0 ~ 1.5m/s, and roughing guarantees that the last average draft of continuous three passages is not less than 16%.The intermediate blank gauge control guarantees that three percentage pass reductions are not less than 16% thickness after by the slab broadening.900 ~ 930 ℃ of

stage start rolling temperatures; 800 ~ 840 ℃ of controls of finishing temperature; Open the cold temperature lower limit set of finishing temperature according to target; Every time draft must>=12%, last three passages accumulative total draft is not less than 40%.

(6) quicken cooling: open 780 ~ 800 ℃ of cold temperature after rolling, 3-6 ℃/s, return 680 ~ 730 ℃ of red temperature.

(7) normalizing: 875 ~ 890 ℃ of normalizing temperatures; Time inside furnace (thickness of slab+80 ~ 85) min, steel plate should be greater than 15min in the stove soaking time.

(8) control is cold: after steel plate went out normalizing furnace, carry out the NCC cooling: steel plate returned red temperature and is controlled at 600 ~ 660 ℃, 5 ~ 10 ℃/s of cooling rate; Normalizing, roll off the production line cooling in heap de-stacking after 72 ~ 94 hours fast after cold soon.

Compared with prior art, the present invention has the following advantages:

A. adopt continuously cast bloom to produce the thick Q345R steel plate of high performance 60 ~ 100mm, reduced production cost, satisfied the requirement that the high-parameters pressurized vessel is made;

B. the low high Mn composition of C system is adopted in the composition design, has satisfied material C eq≤0.40%;

C. in steel, add Nb, V, Ti microalloy element, select reasonable heating process, be aided with high temperature and depress rolling at a slow speed, TMCP rolling technology greatly, utilize the mutagenesis of the operation of rolling to separate out and roll postprecipitation and separate out and improve the steel plate obdurability; In steel, add Ni and improve steel plate 1/4 and the horizontal low-temperature impact toughness of 1/2 thickness; In steel, add Cu, utilize separating out of ε-Cu behind solid solution and the special cooling control technology of normalizing Cu, improve the intensity of steel plate; Adopt normalizing treatment to improve the over-all properties of steel plate, satisfied steel plate Z to performance demands.

D. use continuously cast bloom to produce high performance Q345R slab, operation is simple, technology realizes easily, and general Wide and Thick Slab factory all can produce.

Embodiment

Further specify content of the present invention below in conjunction with embodiment.

Embodiment 1: the refining thickness of slab is the 98mm super-thick steel plate.

The composition content mass percent of steel is seen table 1.

Table 1 98mm super-thick steel plate quality percentage composition

The production craft step of steel and parameter are:

(1) converter steelmaking: converter Intake Quantity 130t, tapping carbon 0.085%, 1650 ℃ of tapping temperatures; Alloy begins to add when tapping to 1/3 left and right sides, adds during to 2/3 left and right sides, in ladle, adds 530kg top slag charge in the tapping process; Feed Al line 350m, Al0.040% in the molten steel, omnidistance Argon behind the stove.

(2) external refining: molten steel is at LF stove 20min conduction time, and always argon blowing time is 45 minutes, white slag hold-time 11min, and the LF stove is fed Si-Ca line 550m, and soft blow argon time 6min adds Ti-Fe before the departures, Ti content 0.020%, C 0.11% sets off.

The control of VD stove: VD (RH) stove is total argon blowing time 35min at the station, vacuumizes vacuum tightness 0.45tor, hold-time 20min; The soft blow argon is greater than 15min, the molten steel hydrogen that goes out to stand firm, H0.8ppm, appear on the stage 1572 ℃ of temperature of departures.

(3) continuous casting control: 8 ℃ of molten steel overheats, 1530 ℃ of middle bag representative temperatures.Roll off the production line stacking slow cooling 48 hours of 300X2280mm section casting blank.

(4) heating: 1240～1260 ℃ of slab heating, come out of the stove 1210 ℃ of heart portion temperature of time inside furnace 380min, slab.

(5) rolling: 1050 ℃ of

stage start rolling temperatures, 960 ℃ of finishing temperatures.The roughing roll speed is 1.5m/s, and rate is greater than 16% under last continuous three passages of roughing.Intermediate blank thickness 187mm.910 ℃ of stage start rolling temperatures, 820 ℃ of finishing temperatures, last three passages accumulative total draft 43%, finished product thickness 98mm.

(6) quicken cooling: open 800 ℃ of cold temperature after rolling, 4 ℃/s, return 690 ℃ of red temperature.

(7) normalizing: 880 ± 5 ℃ of normalizing temperatures; Time inside furnace 180min.

(8) control is cold: steel plate carries out the NCC cooling after going out normalizing furnace: steel plate returns 620 ℃ of red temperature, 6 ℃/s of cooling rate; Normalizing, roll off the production line cooling in heap de-stacking after 83 hours fast after cold soon.

Choose the sample of plate number 1 ~ 15, the present invention produces steel plate quality in kind actual achievement and sees table 2, table 3, table 4.

Steel plate Ceq=0.37 ~ 0.39%.Steel plate is according to the defect detecting test of GB/T2970 standard ultrasonic, whole 1 grade qualified.

Table 2 steel plate tensile property check actual achievement

?

Table 3 steel plate transverse impact merit check actual achievement

Table 4 steel plate Z is to the service check actual achievement

Claims (1)

1. the working method of a super-thick steel plate, production process route be hot metal pretreatment → converter steelmaking → external refining → continuous casting → heating → rolling → quicken cooling → normalizing → control cold → finishing, it is characterized in that:

The chemical constitution percentage composition of steel is C≤0.12, Si=0.20～0.40, and Mn=1.20～1.50, P≤0.008, S≤0.003, AlT=0.03～0.06, Nb+ Ti+ V≤0.10, Cu+Ni≤0.80, Ceq≤0.40%, surplus is Fe and unavoidable impurities;

Process step and processing parameter are:

(1) converter steelmaking: the converter Intake Quantity is controlled by 120～135t, tapping carbon 0.08～0.10%, 1610～1670 ℃ of tapping temperatures; Alloy should begin to add when tapping to 1/3 left and right sides; Add during to 2/3 left and right sides, in ladle, add 400kg above top slag charge or refining slag in the tapping process, feed the Al line behind the stove and must not be less than 200m; Require Al >=0.020% in the molten steel, must keep omnidistance Argon state;

(2) external refining: molten steel is at LF stove conduction time>=18min, total argon blowing time>=35 minutes, white slag hold-time>=10 ~ 12min; The LF stove is fed Si-Ca line or Ca-Fe line>=500m, and the line feeding of LF stove can not mended before VD (RH) stove evacuation completely and fed, and molten steel carries out the operation of soft blow argon before going out LF; The soft blow argon time should be greater than 5min; Add an amount of Ti-Fe according to the molten steel amount before the departures, guarantee that Ti content is controlled at the internal control scope, departures C is by 0.110% control; The control of VD (RH) stove: confirm VD (RH) the stove treatment time according to the molten steel temperature drop rule, require VD (RH) stove at total argon blowing time>=30min that stands, vacuumize, below the vacuum tightness 0.5tor, the hold-time is not less than 15min; The soft blow argon is greater than 10min, the molten steel hydrogen that goes out to stand firm, H≤1.0ppm, appear on the stage 1565～1575 ℃ of temperature of departures;

(3) continuous casting control: big bag adopts long sleeve pipe to add the cast of argon gas seal protection, and the tundish pouring molten steel normal level of liquid degree of depth >=1m, middle bag add insulating covering agent protection cast;

The mouth of a river adds sealing-ring protection cast under adopting, and immerses the molten steel in mold degree of depth >=120mm;

5～10 ℃ of molten steel overheats, 1524 ~ 1534 ℃ of middle bag representative temperatures; Roll off the production line stacking slow cooling 24～72 hours of 300mm strand;

(4) heating: 1200～1280 ℃ of slab heating, heat-up time 10～15min/cm, soaking time is greater than 60min, the upper surface temperature is higher than 10 ~ 20 ℃ of lower surfaces, come out of the stove heart portion temperature >=1200 ℃ of slab;

(5) rolling:

stage start rolling temperature>=1050 ℃, 950～980 ℃ of finishing temperatures;

It is rolling at a slow speed that steel plate rolling requires roughing to adopt high temperature to depress greatly, and the roughing roll speed is reduced to 1.0 ~ 1.5m/s, and roughing guarantees that the last average draft of continuous three passages is not less than 16%; The intermediate blank gauge control guarantees that behind the slab broadening three percentage pass reductions are not less than 16% thickness; 900 ~ 930 ℃ of stage start rolling temperatures; 800 ~ 840 ℃ of controls of finishing temperature; Open the cold temperature lower limit set of finishing temperature according to target; Every time draft must>=12%, last three passages accumulative total draft is not less than 40%;

(6) quicken cooling: open 780 ~ 800 ℃ of cold temperature after rolling, 3-6 ℃/s, return 680 ~ 730 ℃ of red temperature;

(7) normalizing: 875 ~ 890 ℃ of normalizing temperatures; Time inside furnace (thickness of slab+80 ~ 85) min, steel plate should be greater than 15min in the stove soaking time;

(8) control is cold: after steel plate went out normalizing furnace, carry out the NCC cooling: steel plate returned red temperature and is controlled at 600 ~ 660 ℃, 5 ~ 10 ℃/s of cooling rate; Normalizing, roll off the production line cooling in heap de-stacking after 72 ~ 94 hours fast after cold soon.