CN109628827A - A kind of low-temperature welding cracks sensibility high-strength steel plate HYQ620 and its production method - Google Patents

Abstract

A kind of low-temperature welding cracks sensibility high-strength steel plate HYQ620 and its production method.The invention discloses a kind of by choosing cold high-quality molten iron, the pretreatment of KR molten iron, Argon processing, the refining of LF furnace, VD vacuum technology, casting, heap, heating, TMCP rolling technique, steel plate stacking slow cooling and finishing series of steps complete the production of steel plate.Compared with prior art, the present invention is during the rolling process, by adopting TMCP rolling technique, it can guarantee that low-temperature welding cracks sensibility high-strength steel plate HYQ620 original structure is good, it in turn ensures that low-temperature welding cracks sensibility high-strength steel plate HYQ620 properties are met the requirements, also ensures that steel plate has reached requirement, due to not needing to carry out complicated heat treatment process, therefore the production cycle shortens dramatically, and manufacturing cost is also minimized.

Description

A kind of low-temperature welding cracks sensibility high-strength steel plate HYQ620 and its production method

Technical field

The present invention relates to medium plate production technical fields, and in particular to high-intensitive to a kind of low-temperature welding cracks sensibility Steel plate HYQ620 production method.

Background technique

As various engineering constructions develop with welding structure to enlargement constantly to high parameter, large scale, heavy-duty direction Development, Welded Joints quality propose increasingly higher demands low-alloy high-strength steel for welded structures plate, to structural weight reduction Requirement it is further urgent, the intensity rank of steel plate used is gradually increased；For simplified operational procedure and reduce examining for project cost Consider.It is generally desirable to not preheat or low preheated weld.Currently, the production of low welding crack sensitivity steel plate be divided into technique it is quenched With two kinds of Micro Alloying.Hardening and tempering process stability is preferable, is relatively more suitable for big thickness steel plate, and still, hardening and tempering process needs to carry out two Secondary heat treatment, complex procedures, the production cycle is long, higher cost；Non-tempering process is the synthesis based on thermomechanical controlled rolling Using various reinforcing means, alloying element additive amount in steel, improving welding property, due to not needing complexity can be greatly lowered Heat treatment process, therefore the production cycle shortens dramatically, and manufacturing cost is also minimized.The present invention uses the production work of TMCP Skill, -20 DEG C of the low-temperature flexibility of HYQ620 steel plate, -40 DEG C, 60 DEG C of low-temperature impacts can completely foot≤140J, the steel grade its at setting up separately Meter and organizational controls do not need preheating before steel plate weldering or low-temperature prewarming are welded without generating welding cold cracking.With strong Spend high and low temperature good toughness, processing performance and good welding performance, it is wear-resisting, corrosion-resistant the features such as.Current this kind of steel engineering machinery, Water power, nuclear energy etc., demand is larger.

Summary of the invention

In view of the above-mentioned problems, the object of the present invention is to provide a kind of low-temperature welding cracks sensibility high-strength steel plates HYQ620, production is easy, has the characteristics that intensity high and low temperature good toughness, processing performance and good welding performance, is wear-resisting, corrosion-resistant, It is widely used in engineering machinery, water power and nuclear energy field.

It is a further object of the present invention to provide the producers of low-temperature welding cracks sensibility high-strength steel plate HYQ620 a kind of Method.

In order to achieve the above objectives, the technical solution adopted by the present invention is that: a kind of low-temperature welding cracks sensibility high-strength steel Plate HYQ620, the steel plate with a thickness of 12-70mm, the chemical component (unit, wt%) comprising following mass percent: C 0.04 ~0.09, Si 0.10~0.25, Mn 1.50~1.60, P≤0.010, S≤0.003, Als 0.015~0.035, Cr 0.22-0.25, Mo 0.20-0.25, Nb 0.030-0.040, Ti 0.008-0.016, V 0.05-0.06, it is other for Fe and residual Stay element；Carbon equivalent Ceq≤0.40%, weld crack Sensitivity Index Pcm≤0.19%, wherein Ceq=C+Mn/6+ (Cr+Mo+V)/5 + (Ni+Cu)/15,

Pcm=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B。

A kind of production method of low-temperature welding cracks sensitive steel HYQ620 plate, it is characterised in that the following steps are included:

The pretreatment of a.KR molten iron: the molten iron that arrives at a station must take off preceding slag and take off rear slag, guarantee liquid slag layer thickness≤20mm, molten iron is through KR Guarantee molten iron S≤0.005% after stirring desulphurization, guarantees desulfurization cycle≤20min, desulfurization temperature drop≤20 DEG C；

B. pneumatic steelmaking: converter is packed into steel scrap and all uses leftover pieces；Converter terminal control: tapping temperature >=1620 DEG C, 0.03% ≤ C≤0.06% does not allow Argon in tapping process, does not allow that any deoxidier and alloy are added into molten steel；Tapping terminates to adopt With slag retaining cone pushing off the slag, tapping slag is avoided, if pushing off the slag fails, it is necessary to lift furnace in advance, it is ensured that converter slag thickness control is in 40mm Hereinafter, returning P to avoid slag；After molten steel to argon station, prevent that alloy, aluminum steel or auxiliary material and deoxidier are added into molten steel, simultaneously Also prevent Argon.Molten steel is directly hung to the processing of LF furnace, and temperature leaving from station is controlled according to >=1590 DEG C；

C. Argon is handled: argon station is added at one time aluminum steel, requires strong Argon 5-8min, flow 300-500NL/min, steel in argon station Liquid level naked eye diameter control must not be lower than 1580 DEG C in 300~500mm, from argon station temperature；

D.LF refinery practice: after molten steel arrives at a station plus 100-200kg fluorite, 500-700kg lime start slag making, slag making after addition It is lower in view of temperature in the process, it is operated with caution in operating process, avoids LF electrode damage；In slagging process, according to clinker situation Ingredient guarantees shoddye operation if the more sticky increase fluorite of slag, improves slag fluidity, and the when of falling slag is easy；It is de- to control LF refining After carbon, C≤0.03% carries out down slag after decarburization；Second of refining is made in strict accordance with big quantity of slag technological standards Slag prevents the dilute phenomenon of slag and occurs wherein single furnace lime consumption is 800Kg or more；It executes, arrives according to existing 3# continuous casting refinery practice It stands with reference to 2.0m/t steel-aluminium conductor is added, process deoxidier takes aluminum shot, and aluminum shot is controlled with reference to dosage in 30-60Kg, and white slag is kept Time >=15min；Heating terminates to be taken according to Als content in molten steel plus hello aluminum steel is finely adjusted Als, and additional amount is no more than 2.5m/t steel；During LF refining, to one heating after, two heating carry out precious alloy additions, wherein ferrochrome, molybdenum-iron, Nickel plate, ferro-niobium, vanadium iron addition are added in two portions, and are added control according to internal control lower limit for the first time, to according to first time alloying element Content carries out alloy in two heating subsequent processes and adds, and guarantees that ingredient reaches in internal control and limits；Ferrotianium requires to be added in all alloys It is added after complete；LF refining upper VD furnace liquid steel temperature leaving from station is according to 1600-1620 DEG C of scope control；

E.VD vacuum technology: it is required that when vacuum degree≤67Pa the dwell time controlled by >=18min, soft blow 3- after vacuum breaker 5min, temperature leaving from station ensure middle baotou steel water superheat control within the scope of 5~20 DEG C；

F. continuous casting process: 3# conticaster 350mm section is taken to be produced；

G. heat: preheating section < 1050 DEG C, two 1210~1230 DEG C of heating, 1200~1220 DEG C of soaking zone (walks middle limit), when heating Between according to 10~13min/cm control, steel billet soaking time, soaking time > 30min can be appropriately extended), guarantee steel billet uniformly burn Thoroughly, forbid to overheat burning；

H. controlled rolling: use II type controlled rolling: a stage start rolling temperature controls between 1000~1120 DEG C, and start rolling temperature is not less than 1000 DEG C, 1020-1100 DEG C of start rolling temperature of≤16mm, the steel thickness that dries in the air stops rolling the steel 60-65mm that dries in the air, and the two-stage guarantees single pass pressure Rate >=15% adds up reduction ratio >=60%；820~850 DEG C of two-stage rolling temperature≤950 DEG C, finishing temperature, after steel plate rolling Be quickly cooled down into ACC cooling facility for laminar flow, enter 725 DEG C of coolant-temperature gage >, 520-540 DEG C of red temperature, cooling rate control 12~ It 20 DEG C/s, can repeatedly cool down, 1.3~2.0m/s of roller speed；1020-1100 DEG C of start rolling temperature of > 16-30mm, the steel thickness that dries in the air stops rolling Dry in the air steel 80-90mm, 810~840 DEG C of two-stage rolling temperature≤900 DEG C, finishing temperature, and it is cold that ACC laminar flow is entered after steel plate rolling But device is quickly cooled down, and enters 730 DEG C of coolant-temperature gage >, 510-530 DEG C of red temperature, cooling rate is controlled in 10~16 DEG C/s, Ke Yiduo Secondary cooling, 1.0~1.5m/s of roller speed；1020-1100 DEG C of start rolling temperature of > 30-50mm, the steel thickness that dries in the air stops rolling the steel 90-100mm that dries in the air, 800~820 DEG C of two-stage rolling temperature≤850 DEG C, finishing temperature enter the fast quickly cooling of ACC cooling facility for laminar flow after steel plate rolling But, enter 730 DEG C of coolant-temperature gage >, 500-520 DEG C of red temperature, cooling rate is controlled in 11~17 DEG C/s, can repeatedly be cooled down, roller speed 1.0~1.5m/s；1020-1100 DEG C of start rolling temperature of > 50-70mm, the steel thickness that dries in the air stops rolling the steel 120-140mm that dries in the air, two-stage open rolling 790~810 DEG C of temperature≤900 DEG C, finishing temperature enter ACC cooling facility for laminar flow and are quickly cooled down, enter coolant-temperature gage after steel plate rolling 740 DEG C of >, 490-510 DEG C of red temperature, cooling rate is controlled in 11~19 DEG C/s, can repeatedly be cooled down, 1.0~1.5m/s of roller speed； Ensure that steel billet temperature is uniform, last 1 passage does not allow to be thrown a little further when throwing steel using high pressure water, body of roll water is forbidden to be poured onto head； Using circulation rolling mode when rolling, for coordinating the rhythm of rolling and aligning: using " two and half " or " three according to steel plate thickness The milling method of block half ", that is, roll one piece and dry in the air one piece, or roll one piece and dry in the air two pieces, enters coolant-temperature gage at this time lower than 10-20 DEG C of red temperature It executes；

I. it aligns: it is straight to rob temperature correction, it is ensured that steel-plate shape is at least aligned 3 times depending on template situation, the band temperature correction again of≤20mm thick steel plate During straight under the premise of existing control straightening temperature, respectively pressed from both sides up and down with one block of slab under magnetic disc suspending in time after having rectified The steel plate firmly just rectified, plate shape caused by the steel plate after preventing leveling is lower as temperature are restored, and lead to wooden dipper song again, solve accordingly Certainly thin plate template floats Qu Wenti；

J. heap is cold: progress heap is cold in burial pit after steel plate is offline, cold temperature >=450 DEG C of heap, stack cold time >=36 hour, and does Good Insulation, reduce cooling rate, improve steel plate inspection quality, steel billet temperature be down to 50 DEG C -80 DEG C or less after can de-stacking, be made Invention.

The present invention is by choosing high-quality molten iron, the pretreatment of KR molten iron, Argon processing, the refining of LF furnace, VD vacuum technology, pouring Note, heap is cold, heating, TMCP rolling technique, steel plate stacking slow cooling and finishing series of steps complete the production of steel plate.Guaranteeing On the basis of HYQ620 ingredient, the alloying element contents such as appropriate adjustment C, Mo, Nb and ratio, P, S etc. influence in strict control steel The harmful element content of steel plate plasticity and toughness is returned by LF refining dross inclusion adsorption, VD vacuum dehydrogenation using steel plate stacking slow cooling certainly The methods of fire processing, ensure that low-temperature welding cracks sensibility steel grade HYQ620 12-70mm thickness steel plate internal residual stress most Smallization, internal soundness is qualified, and performance indexes reaches standard requirements.In smelting process, P(phosphorus in strict control steel), S Harmful elements such as (sulphur) guarantee that the degree of purity of molten steel basically reaches clean steel level.Using a step-up temperature, heat preservation, samming Mode, suitably reduction heating temperature, not only eliminate the residual stress of molten steel solidification process generation, and avoid inside steel billet former Beginning austenite grain is excessively grown up, and solid foundation is established in the refinement for steel billet crystal grain during the rolling process.During the rolling process, lead to It crosses and adopts TMCP rolling technique, can guarantee that low-temperature welding cracks sensibility high-strength steel plate HYQ620 original structure is good, again It ensure that low-temperature welding cracks sensibility high-strength steel plate HYQ620 properties are met the requirements, also ensure that steel plate has reached use It is required that the production cycle shortens dramatically, and manufacturing cost is also minimized due to not needing to carry out complicated heat treatment process.

Specific embodiment

Below with reference to embodiment, feature of the invention is further described.

A kind of 12-70mm low-temperature welding cracks sensibility high-strength steel plate HYQ620 is produced, includes following mass percent Chemical component (unit, wt%): C:0.04~0.09, Si:0.10~0.25, Mn:1.50~1.60, P≤0.010, S≤ 0.003, Als:0.015~0.035, Cr:0.22-0.25, Mo:0.20-0.25, Nb:0.030-0.040, Ti:0.008- 0.016, V:0.05-0.06, other is Fe and relict element；

Carbon equivalent [Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15]≤0.40%, weld crack Sensitivity Index [Pcm=C+ Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B]≤0.19%。

The production method of above-mentioned steel plate is realized according to the following steps: high-quality molten iron-KR molten iron pretreatment --- at Argon Reason-LF furnace refining-VD Fruit storage-casting-heap is cold-and heating-rolling-steel plate heap is cold-and finishing-enters Kucheng Product.Slag and slag after taking off before the molten iron that arrives at a station in KR molten iron pretreatment must be taken off, guarantee liquid slag layer thickness≤20mm, molten iron Guarantee molten iron S≤0.005% after KR stirring desulphurization, guarantees desulfurization cycle≤20min, desulfurization temperature drop≤20 DEG C；In the converter In smelting, converter is packed into steel scrap and all uses leftover pieces；Converter terminal control: tapping temperature >=1620 DEG C, 0.03%≤C≤ 0.06%, do not allow Argon in tapping process, allow that any deoxidier and alloy are added into molten steel；Tapping terminates using gear Slag bore pushing off the slag, avoid tapping slag, if pushing off the slag fail, it is necessary to lift furnace in advance, it is ensured that converter slag thickness control in 40mm hereinafter, P is returned to avoid slag；After molten steel to argon station, prevent that alloy, aluminum steel or auxiliary material and deoxidier are added into molten steel, while also preventing Argon.Molten steel is directly hung to the processing of LF furnace, and temperature leaving from station is controlled according to >=1590 DEG C；In Argon processing, argon station is primary Property aluminum steel is added, require strong Argon 5-8min in argon station, flow 300-500NL/min, molten steel face naked eye diameter control 300~ 500mm must not be lower than 1580 DEG C from argon station temperature；In the LF refining, molten steel adds 100-200kg fluorite, 500- after arriving at a station 700kg lime, starts slag making after addition, lower in view of temperature in slagging process, operates with caution in operating process, avoids LF electrode Damage；In slagging process, according to clinker situation ingredient, if the more sticky increase fluorite of slag, guarantees shoddye operation, improve clinker flowing Property, the when of falling slag be easy fall；After controlling LF refining decarburization, C≤0.03% carries out down slag after decarburization；Second of refining is tight According to big quantity of slag technological standards progress slag making, (single furnace lime consumption must be controlled in 800Kg or more) lattice, prevent the dilute phenomenon hair of slag It is raw；It executes, arrives at a station with reference to 2.0m/t steel-aluminium conductor is added, process deoxidier takes aluminum shot, aluminium according to existing 3# continuous casting refinery practice Grain is controlled with reference to dosage in 30-60Kg, white slag retention time >=15min；Heating terminates to be taken plus fed according to Als content in molten steel Aluminum steel is finely adjusted Als, and additional amount is no more than 2.5m/t steel；During LF refining, after being heated to one, carried out in two heating Precious alloy is added, and wherein ferrochrome, molybdenum-iron, nickel plate, ferro-niobium, vanadium iron addition are added in two portions, and is added for the first time according under internal control Limit control is added to carry out alloy in two heating subsequent processes according to first time alloying element content, guarantees that ingredient reaches internal control Middle limit；Ferrotianium requires to add after all alloys have been added；LF refining upper VD furnace liquid steel temperature leaving from station is according to 1600-1620 DEG C Scope control；In VD refining, it is desirable that the dwell time is controlled by >=18min when vacuum degree≤67Pa, after vacuum breaker Soft blow 3-5min, temperature leaving from station ensure middle baotou steel water superheat control within the scope of 5~20 DEG C；In the continuous casting, 3# is taken Conticaster 350mm section is produced；In steel billet cleaning, with flame gun to steel ingot width 1/2 after steel billet slow cooling Position is cleared up, and the control of cleaning width is cleared up deep-controlled in 5-10mm in 30-50CM；In the heating, heating temperature And heating time is as follows: preheating section < 1050 DEG C, and two 1210~1230 DEG C of heating, 1200~1220 DEG C of soaking zone (walks middle limit), adds The hot time controls according to 10~13min/cm, and steel billet soaking time (soaking time > 30min) can be appropriately extended；Guarantee that steel billet is equal It is even to grill thoroughly, forbid to overheat burning；In the controlled rolling, controlled rolling: use II type controlled rolling: stage start rolling temperature control 1000~ Between 1120 DEG C, start rolling temperature is not less than 1000 DEG C, and 1020-1100 DEG C of start rolling temperature of≤16mm, the steel thickness that dries in the air stops rolling the steel 60- that dries in the air 65mm, two-stage guarantee single pass reduction ratio >=15%, add up reduction ratio >=60%；Two-stage rolling temperature≤950 DEG C, finish to gauge 820~850 DEG C of temperature, ACC cooling facility for laminar flow is entered after steel plate rolling and is quickly cooled down, enters 725 DEG C of coolant-temperature gage >, red temperature 520-540 DEG C, cooling rate is controlled in 12~20 DEG C/s, can repeatedly be cooled down, 1.3~2.0m/s of roller speed；> 16-30mm start rolling temperature 1020-1100 DEG C, the steel thickness that dries in the air stops rolling the steel 80-90mm that dries in the air, 810~840 DEG C of two-stage rolling temperature≤900 DEG C, finishing temperature, Enter ACC cooling facility for laminar flow after steel plate rolling to be quickly cooled down, enters 730 DEG C of coolant-temperature gage >, 510-530 DEG C of red temperature, cooling rate Control can be cooled down repeatedly, 1.0~1.5m/s of roller speed in 10~16 DEG C/s；It 1020-1100 DEG C of start rolling temperature of > 30-50mm, dries in the air Steel thickness stops rolling the steel 90-100mm that dries in the air, and 800~820 DEG C of two-stage rolling temperature≤850 DEG C, finishing temperature, steel plate rolling is laggard Enter the rapid cooling of ACC cooling facility for laminar flow, enters 730 DEG C of coolant-temperature gage >, 500-520 DEG C of red temperature, cooling rate is controlled 11~17 DEG C/s, it can repeatedly cool down, 1.0~1.5m/s of roller speed；1020-1100 DEG C of start rolling temperature of > 50-70mm, the steel thickness that dries in the air, which stops rolling, to dry in the air It is cold to enter ACC laminar flow for steel 120-140mm, 790~810 DEG C of two-stage rolling temperature≤900 DEG C, finishing temperature after steel plate rolling But device is quickly cooled down, and enters 740 DEG C of coolant-temperature gage >, 490-510 DEG C of red temperature, cooling rate is controlled in 11~19 DEG C/s, Ke Yiduo Secondary cooling, 1.0~1.5m/s of roller speed；Ensure that steel billet temperature is uniform, last 1 passage does not allow to throw when throwing steel remote using high pressure water A bit, body of roll water is forbidden to be poured onto head；It, must be using circulation rolling mode when rolling: root in order to coordinate to roll and align rhythm According to steel plate thickness using the milling method of " two and half " or " three and half ", it may be assumed that roll one piece and dry in the air one piece, or roll one piece and dry in the air two pieces.Note: 1. entering coolant-temperature gage lower than technique requirement, 10-20 DEG C of red temperature execution need to be reduced.In the aligning: it is straight to rob temperature correction, it is ensured that steel Plate plate shape, is at least aligned 3 times depending on template situation.< 20mm steel plate is straight in the process in existing control straightening temperature with temperature correction again Under the premise of, the steel plate just rectified respectively is clamped with one block of slab up and down, the steel plate after preventing leveling under magnetic disc suspending in time after having rectified Plate shape restores (temperature is lower after preventing plank cooling), leads to wooden dipper song again；To effective solution thin plate template float it is bent Problem.In the slow cooling: progress heap is cold in burial pit after steel plate is offline, cold temperature >=450 DEG C of heap, and stack cold time >=36 are small When, so that the present invention be made.

Mechanical mechanics property analysis is carried out to steel plate obtained:

HYQ620 12-70mm low-temperature welding cracks sensibility high-strength steel plate HYQ620 mechanical mechanics property

HYQ620 12-70mm, which adds, does low temperature impact properties

This trial production 12-70mm thickness HYQ620 is 24 batches total, in which: yield strength is controlled in 520~626 MPa, average out to To 556 MPa, than standard affluence 66MPa；Tensile strength is controlled in 660-709MPa, has averagely been reached 672MPa, has been compared standard Rich 52MPa；Elongation is controlled in 24%-41%, averagely reaches 31%, than standard affluence 13%；Wherein -20 DEG C of V-type ballistic works Control has averagely reached 277J in 216-332J, adds -40 DEG C of V-type ballistic works done control in 182-275J, averagely reaches 211J adds -60 DEG C of V-type ballistic works done control in 162-205J, has averagely reached 180J, from data, be fully achieved low The level of warm welding crack sensibility high-strength steel plate HYQ620.

Outer inspection and flaw detection: examining outside the steel plate developed, and certified product rate 100% is detected a flaw by JB/T 47030.3-2005, closes Level-one rate is 100%, has reached desired effect.

Only metallographic structure detects field trash: by GB/T 10561, " the measurement standard of nonmetallic inclusionsin steel content is graded Figure microexamination method " field trash grading is carried out, each type impurity A+B+C+D < 2.0, acquired tissue is with granular bainite+iron element Based on body.

Described above is only presently preferred embodiments of the present invention, and above-mentioned specific embodiment is not limitation of the present invention, Retouching, modification or the equivalent replacement that all those skilled in the art are made as described above, belong to guarantor of the invention Protect range.

Claims (2)

1. a kind of low-temperature welding cracks sensibility high-strength steel plate HYQ620, it is characterised in that: the steel plate with a thickness of 12- 70mm, the chemical component (unit, wt%) comprising following mass percent: C 0.04~0.09, Si 0.10~0.25, Mn 1.50~1.60, P≤0.010, S≤0.003, Als 0.015~0.035, Cr 0.22-0.25, Mo 0.20-0.25, Nb 0.030-0.040, Ti 0.008-0.016, V 0.05-0.06, other is Fe and relict element；Carbon equivalent Ceq≤0.40%, weldering Crack-sensitivity indices P cm≤0.19% is connect, wherein Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15,

Pcm=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B。

2. a kind of production method of low-temperature welding cracks sensitive steel HYQ620 plate, it is characterised in that the following steps are included:

The pretreatment of a.KR molten iron: the molten iron that arrives at a station must take off preceding slag and take off rear slag, guarantee liquid slag layer thickness≤20mm, molten iron is through KR Guarantee molten iron S≤0.005% after stirring desulphurization, guarantees desulfurization cycle≤20min, desulfurization temperature drop≤20 DEG C；

B. pneumatic steelmaking: converter is packed into steel scrap and all uses leftover pieces；Converter terminal control: tapping temperature >=1620 DEG C, 0.03% ≤ C≤0.06% does not allow Argon in tapping process, does not allow that any deoxidier and alloy are added into molten steel；Tapping terminates to adopt With slag retaining cone pushing off the slag, tapping slag is avoided, if pushing off the slag fails, it is necessary to lift furnace in advance, it is ensured that converter slag thickness control is in 40mm Hereinafter, returning P to avoid slag；After molten steel to argon station, prevent that alloy, aluminum steel or auxiliary material and deoxidier are added into molten steel, simultaneously Also prevent Argon, molten steel is directly hung to the processing of LF furnace, and temperature leaving from station is controlled according to >=1590 DEG C；

C. Argon is handled: argon station is added at one time aluminum steel, requires strong Argon 5-8min, flow 300-500NL/min, steel in argon station Liquid level naked eye diameter control must not be lower than 1580 DEG C in 300~500mm, from argon station temperature；

D.LF refinery practice: after molten steel arrives at a station plus 100-200kg fluorite, 500-700kg lime start slag making, slag making after addition It is lower in view of temperature in the process, it is operated with caution in operating process, avoids LF electrode damage；In slagging process, according to clinker situation Ingredient guarantees shoddye operation if the more sticky increase fluorite of slag, improves slag fluidity, and the when of falling slag is easy；It is de- to control LF refining After carbon, C≤0.03% carries out down slag after decarburization；Second of refining is made in strict accordance with big quantity of slag technological standards Slag prevents the dilute phenomenon of slag and occurs wherein single furnace lime consumption is 800Kg or more；It executes, arrives according to existing 3# continuous casting refinery practice It stands with reference to 2.0m/t steel-aluminium conductor is added, process deoxidier takes aluminum shot, and aluminum shot is controlled with reference to dosage in 30-60Kg, and white slag is kept Time >=15min；Heating terminates to be taken according to Als content in molten steel plus hello aluminum steel is finely adjusted Als, and additional amount is no more than 2.5m/t steel；During LF refining, to one heating after, two heating carry out precious alloy additions, wherein ferrochrome, molybdenum-iron, Nickel plate, ferro-niobium, vanadium iron addition are added in two portions, and are added control according to internal control lower limit for the first time, to according to first time alloying element Content carries out alloy in two heating subsequent processes and adds, and guarantees that ingredient reaches in internal control and limits；Ferrotianium requires to be added in all alloys It is added after complete；LF refining upper VD furnace liquid steel temperature leaving from station is according to 1600-1620 DEG C of scope control；

E.VD vacuum technology: it is required that when vacuum degree≤67Pa the dwell time controlled by >=18min, soft blow 3- after vacuum breaker 5min, temperature leaving from station ensure middle baotou steel water superheat control within the scope of 5~20 DEG C；

F. continuous casting process: 3# conticaster 350mm section is taken to be produced；

G. heat: preheating section < 1050 DEG C, two 1210~1230 DEG C of heating, 1200~1220 DEG C of soaking zone (walks middle limit), when heating Between according to 10~13min/cm control, steel billet soaking time, soaking time > 30min can be appropriately extended), guarantee steel billet uniformly burn Thoroughly, forbid to overheat burning；

H. controlled rolling: use II type controlled rolling: a stage start rolling temperature controls between 1000~1120 DEG C, and start rolling temperature is not less than 1000 DEG C, 1020-1100 DEG C of start rolling temperature of≤16mm, the steel thickness that dries in the air stops rolling the steel 60-65mm that dries in the air, and the two-stage guarantees single pass pressure Rate >=15% adds up reduction ratio >=60%；820~850 DEG C of two-stage rolling temperature≤950 DEG C, finishing temperature, after steel plate rolling Be quickly cooled down into ACC cooling facility for laminar flow, enter 725 DEG C of coolant-temperature gage >, 520-540 DEG C of red temperature, cooling rate control 12~ It 20 DEG C/s, can repeatedly cool down, 1.3~2.0m/s of roller speed；1020-1100 DEG C of start rolling temperature of > 16-30mm, the steel thickness that dries in the air stops rolling Dry in the air steel 80-90mm, 810~840 DEG C of two-stage rolling temperature≤900 DEG C, finishing temperature, and it is cold that ACC laminar flow is entered after steel plate rolling But device is quickly cooled down, and enters 730 DEG C of coolant-temperature gage >, 510-530 DEG C of red temperature, cooling rate is controlled in 10~16 DEG C/s, Ke Yiduo Secondary cooling, 1.0~1.5m/s of roller speed；1020-1100 DEG C of start rolling temperature of > 30-50mm, the steel thickness that dries in the air stops rolling the steel 90-100mm that dries in the air, 800~820 DEG C of two-stage rolling temperature≤850 DEG C, finishing temperature enter the fast quickly cooling of ACC cooling facility for laminar flow after steel plate rolling But, enter 730 DEG C of coolant-temperature gage >, 500-520 DEG C of red temperature, cooling rate is controlled in 11~17 DEG C/s, can repeatedly be cooled down, roller speed 1.0~1.5m/s；1020-1100 DEG C of start rolling temperature of > 50-70mm, the steel thickness that dries in the air stops rolling the steel 120-140mm that dries in the air, two-stage open rolling 790~810 DEG C of temperature≤900 DEG C, finishing temperature enter ACC cooling facility for laminar flow and are quickly cooled down, enter coolant-temperature gage after steel plate rolling 740 DEG C of >, 490-510 DEG C of red temperature, cooling rate is controlled in 11~19 DEG C/s, can repeatedly be cooled down, 1.0~1.5m/s of roller speed； Ensure that steel billet temperature is uniform, last 1 passage does not allow to be thrown a little further when throwing steel using high pressure water, body of roll water is forbidden to be poured onto head； Using circulation rolling mode when rolling, for coordinating the rhythm of rolling and aligning: using " two and half " or " three according to steel plate thickness The milling method of block half ", that is, roll one piece and dry in the air one piece, or roll one piece and dry in the air two pieces, enters coolant-temperature gage at this time lower than 10-20 DEG C of red temperature It executes；

I. it aligns: it is straight to rob temperature correction, it is ensured that steel-plate shape is at least aligned 3 times depending on template situation, the band temperature correction again of≤20mm thick steel plate During straight under the premise of existing control straightening temperature, respectively pressed from both sides up and down with one block of slab under magnetic disc suspending in time after having rectified The steel plate firmly just rectified, plate shape caused by the steel plate after preventing leveling is lower as temperature are restored, and lead to wooden dipper song again, solve accordingly Certainly thin plate template floats Qu Wenti；

J. heap is cold: progress heap is cold in burial pit after steel plate is offline, cold temperature >=450 DEG C of heap, stack cold time >=36 hour, and does Good Insulation, reduce cooling rate, improve steel plate inspection quality, steel billet temperature be down to 50 DEG C -80 DEG C or less after can de-stacking, be made Invention.