CN105525210A

CN105525210A - Low-yield-ratio Q390GJ construction steel plate and production method thereof

Info

Publication number: CN105525210A
Application number: CN201610034183.8A
Authority: CN
Inventors: 高军; 杨雄; 陆斌; 黄楠; 惠鑫; 刘泽田; 刘秀英; 吴鹏飞
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2016-01-18
Filing date: 2016-01-18
Publication date: 2016-04-27
Anticipated expiration: 2036-01-18
Also published as: CN105525210B

Abstract

The invention discloses a low-yield-ratio Q390GJ construction steel plate and a production method thereof, and belongs to the technical field of construction steel. The steel plate is composed of, by weight, 0.15%-0.17% of C, 0.30%-0.40% of Si, 1.45%-1.55% of Mn, 0-0.015% of P, 0-0.010% of S, 0.03%-0.04% of Nb, 0.03%-0.04% of V, 0.01%-0.02% of Ti, 0.020%-0.040% of Als, and the balance Fe and impurities. The production method comprises the following steps of 1, smelting, 2, continuous casting, 3, heating, 4, rolling and cooling, and 5, finishing and flaw detection. The production cycle is shortened and the cost is reduced. The finished steel plate has good performance and can be applied to the fields such as high rises, super high rises, factories and mines, towers, and long-span and large-scale structure engineering construction.

Description

A kind of low yield strength ratio Q390GJ steel plate for building and production method thereof

Technical field

The present invention is specifically related to a kind of low yield strength ratio Q390GJ steel plate for building and production method thereof, belongs to construction(al)steel technical field.

Background technology

The many advantages such as steel building has superior shock resistance, environmental protection, quick construction is convenient, space availability ratio is high, the unique novelty of design model, have now become the developing direction of building structure in the world.Steel plate for building is mainly used in the stressed complexity such as Highrise buildings, high-rise building, large span stadiums, airport, railway station, conference and exhibition center, steel-structure factory building and power transmission and transformation high tower, large-scale construction engineering that reliability requirement is higher, require that steel plate just has low yield strength ratio, good toughness and plasticity, narrow yield-point fluctuation range and less thickness effect, anti-lamellar tearing ability (thickness directional properties), good welding property, excellent extension property and low-Cycle Fatigue Characteristics, have certain fire performance.

Current domestic same level construction(al)steel patent and document have:

Chinese patent CN102876970A discloses " yield strength >=390MPa Steels for High Rise Buildings and production method ", Ingredient percent is: C0.14 ~ 0.18, Si0.3 ~ 0.5,0.6, Mn1.45 ~ 1.6, Nb0.035 ~ 0.050, V0.045 ~ 0.065, Ti0.007 ~ 0.017, Al0.015 ~ 0.050, Ca0.001 ~ 0.005, P < 0.025, S < 0.005, all the other are Fe and inevitable impurity.Hot metal pretreatment, converter smelting, LF refining, RH process, continuous casting, heating, rolling, section cooling, normalizing, the on a small quantity method of water-spraying control is adopted to produce yield strength 370-490MPa, tensile strength >=490MPa, yield tensile ratio≤0.77,-20 DEG C of low-temperature impact work >=100J, the Plate Steel for building of relative reduction in area >=35%.

Chinese patent CN102330020A discloses " manufacture method of yield strength 345-390MPa ductility steel plate ", chemical component weight per-cent is: C:0.08 ~ 0.20%, Si:0.03 ~ 0.55%, Mn:0.8 ~ 1.70%, P≤0.015%, S≤0.010%, V:0.015 ~ 0.05%, Nb:0.01 ~ 0.07%, Ti:0.005 ~ 0.05%, N:0.003 ~ 0.012%, and all the other are Fe and inevitable impurity.The method of employing hot metal pretreatment, converter smelting, refining, continuous casting, heating, controlled rolling and controlled cooling, normalizing, water-spraying control produces yield strength 345-390MPa ductility steel plate, can be widely used in bridge steel plate, construction(al)steel, ship steel.

Document " development of 120mm heavy thickness Q390GJC-Z35 Steels for High Rise Buildings " discusses the trial-production of Nanyang Chinese smelting special steel heavy thickness Q390GJ, chemical composition is C:0.15 ~ 0.18%, Si:0.3 ~ 0.45%, Mn:1.45 ~ 1.55%, P≤0.015%, S≤0.003%, Nb+V+Ti≤0.22, Als:0.03 ~ 0.05%, surplus is Fe and inevitable impurity.The method of employing hot metal pretreatment, converter smelting, LF refining, VD process, die casting, heating, controlled rolling and controlled cooling, normalizing, water-spraying control produces Q390GJC Plate Steel for building.

The common weak point of above technical scheme is, above patent all needs through normalizing and water-cooled process, proposes requirement to production equipment, add the production cycle, improve cost, and all for the steel plate of the special think gauge of more than 100mm, inapplicable for common buildings steel plate.

Summary of the invention

Therefore, the object of the invention is to provide a kind of low yield strength ratio, there is good plasticity and toughness, and excellent anti-lamellar tearing performance, and production cost is lower, not by producing equipment restriction, process-cycle is short, the low yield strength ratio Q390GJ steel plate for building that specification is controlled, yield strength >=390MPa, yield tensile ratio is less than 0.79, 0 DEG C of impact of collision merit is greater than 34J, its chemical composition is by weight percentage: C:0.15 ~ 0.17%, Si:0.30 ~ 0.40%, Mn:1.45 ~ 1.55%, P≤0.015%, S≤0.010%, Nb:0.03 ~ 0.04%, V:0.03 ~ 0.04%, Ti:0.01 ~ 0.02%, Als:0.020 ~ 0.040%, all the other are Fe and inevitable impurity element.

Present invention also offers the working method of above-mentioned low yield strength ratio Q390GJ steel plate for building, said method comprising the steps of:

Step one is smelted:

Adopt through the pretreated molten iron of desulfurization and high-quality steel scrap as raw material, bottom-blowing of converter adopts omnidistance Argon pattern, terminal hit at first time, causes molten steel nitrogen pick-up to reduce because re-blowing.The further deoxidation of LF ladle refining furnace, desulfurization, removal are mingled with, adjusting component and temperature, to strictly control Argon intensity, Argon curve is formulated according to the principle that early stage is strong, mid-term is comparatively strong, the later stage is weak, while guarantee deoxidation, dark desulfurization, alloying, reduce secondary oxidation and the nitrogen pick-up of refining process.RH operation adopts the dark degasification technique of circulation, ensureing significantly to reduce the gas contents such as hydrogen, oxygen, nitrogen under the prerequisite that liquid steel temperature is stable, reduce obnoxious flavour to the disadvantageous effect of steel, the weight percent finally obtaining molten steel is C:0.15 ~ 0.17%, Si:0.30 ~ 0.40%, Mn:1.45 ~ 1.55%, P≤0.015%, S≤0.010%, Nb:0.03 ~ 0.04%, V:0.03 ~ 0.04%, Ti:0.01 ~ 0.02%, Als:0.020 ~ 0.040%, and surplus is Fe and inevitable impurity.

Step 2 continuous casting:

Step 3 heats;

To plate slab heating in process furnace, fully ensure plate slab Heating temperature and soaking time.Heating and temperature control, at 1180 DEG C-1220 DEG C, controls at 200-240min heat-up time, ensures the abundant solid solution of alloying element, plate slab homogeneous temperature.

Step 4 rolling and cooling:

Rolling adopts two-stage control rolling, i.e. austenite recrystallization district controlled rolling (usually claiming rough rolling step) and austenite non-recrystallization zone controlled rolling (usually claiming the finish rolling stage).Pass deformation is strengthened during roughing, start rolling temperature is 1160 ~ 1200 DEG C, the relative draft of single pass has at least more than two passages to control more than 25%, each pass deformation is strictly controlled during finish rolling, finish rolling start rolling temperature≤920 DEG C, open rolling thickness is 1.3-3.0 times of finished product thickness, has twice more than draft >20% at least, last percentage pass reduction >10%.Finishing temperature 850-860 DEG C, rolls rear steel plate and adopts controlled cooling model, final cooling temperature 660-680 DEG C, obtains the tiny and uniform ferrite+pearlitic structure of crystal grain.

Step 5 finishing and flaw detection.

Further, step 2 is specially:

Continuous caster is straight curved type continuous caster, adopt the dynamic secondary cooling technology of solidification end dynamic soft-reduction, induction stirring and optimization, by constant temperature, permanent pulling rate technique, alleviate the defects such as continuously cast bloom center segregation, center porosity, crackle, oscillation mark, final production goes out the thick high-quality continuous casting steel billet of 250mm, 300mm.

Further, step 5 is specially:

All carry out line flaw detection after hot-rolled steel sheet cooling, after flaw detection, steel plate keeps dry, and for the steel plate of line flaw detection not carrying out flaw detection of rolling off the production line, carry out according to the regulation of non-destructive testing standard JB/T4730.3 and judge, qualified rank is I grade.

Beneficial effect of the present invention is: a kind of low yield strength ratio Q390GJ of the present invention steel plate for building, by rational chemical composition design, finished steel plate is made to obtain better mechanical property, production method of the present invention, direct employing normalizing rolling, without the need to off-line normalizing thermal treatment, shorten the production cycle, also reduce production cost simultaneously, finished steel plate has good plasticity and toughness and excellent anti-lamellar tearing performance, can be applicable to the fields such as high level, Super High, factories and miness, pylon, large span and large scale structure engineering construction.

Accompanying drawing explanation

Fig. 1 is the schema of the production method of a kind of low yield strength ratio of the present invention Q390GJ steel plate for building;

Fig. 2 is the finished product metallographic structure figure at embodiment 2 steel plate 1/4 thickness place.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described:

Low yield strength ratio Q390GJ of the present invention steel plate for building, yield strength >=390MPa, yield tensile ratio is less than 0.79,0 DEG C of impact of collision merit is greater than 34J, chemical composition is by weight percentage: C:0.15 ~ 0.17%, Si:0.30 ~ 0.40%, Mn:1.45 ~ 1.55%, P≤0.015%, S≤0.010%, Nb:0.03 ~ 0.04%, V:0.03 ~ 0.04%, Ti:0.01 ~ 0.02%, Als:0.020 ~ 0.040%, and all the other are Fe and impurity.The flow process of steel plate working method as shown in Figure 1.

Embodiment 1

Raw material molten iron is through Deep Desulphurization of Hot Metal, and converter top and bottom blowing, ladle argon-blown, LF external refining, RH vacuum-treat and continuous casting process obtain the 250mm heavy slab of the per-cent of chemical component weight shown in table 1.Slab heating temperature 1200 DEG C, heat-up time 220min, first stage start rolling temperature 1180 DEG C, the relative draft of single pass has at least more than two passages to control more than 25%, when rolled piece thickness is 75mm, roller-way is treated temperature is to 910 DEG C, carries out subordinate phase rolling subsequently, finishing temperature is 850 DEG C, and finished steel plate thickness is 25mm.After rolling terminates, steel plate enters accelerating cooling (ACC) device, is cooled to 680 DEG C with the speed of 5 DEG C/s, and heat rectifys rear cold bed cooling.Carry out line flaw detection and finishing process afterwards, finally can obtain steel plate finished product.

Embodiment 2

Embodiment is with embodiment 1, and wherein Heating temperature is 1200 DEG C, heat-up time 213min, the start rolling temperature of first stage rolling is 1180 DEG C, and the start rolling temperature of subordinate phase rolling is 900 DEG C, and rolled piece thickness is 125mm, finishing temperature is 854 DEG C, and finished steel plate thickness is 50mm.Steel plate speed of cooling is 8 DEG C/s, and final cooling temperature is 670 DEG C.Heat rectifys rear cold bed cooling.Carry out flaw detection and finishing process afterwards, finally can obtain steel plate finished product.As shown in Figure 2, metallographic structure is the tiny and uniform ferrite+pearlitic structure of crystal grain to the metallographic structure figure at embodiment 2 steel plate 1/4 thickness place.

Embodiment 3

Embodiment is with embodiment 1, and wherein Heating temperature is 1200 DEG C, heat-up time 230min, the start rolling temperature of first stage rolling is 1185 DEG C, and the start rolling temperature of subordinate phase rolling is 890 DEG C, and rolled piece thickness is 120mm, finishing temperature is 860 DEG C, and finished steel plate thickness is 60mm.Steel plate speed of cooling is 8 DEG C/s, and final cooling temperature is 660 DEG C.Heat rectifys rear cold bed cooling.Carry out flaw detection and finishing process afterwards, finally can obtain steel plate finished product.

The chemical composition (wt%) of embodiment 1 ~ 3 is as shown in table 1.

Table 1

Embodiment	C	Si	Mn	P	S	Nb	V	Ti	Als
										1	0.15	0.30	1.45	0.006	0.003	0.030	0.030	0.010	0.020
2	0.16	0.35	1.50	0.008	0.005	0.035	0.035	0.015	0.030
										3	0.17	0.40	1.55	0.012	0.007	0.040	0.040	0.020	0.040

Conventional mechanical property, Z-direction tensile property, impact property inspection are carried out to the steel plate of embodiment 1 ~ 3, the results are shown in Table 2.

Table 2

As can be seen from Table 2, steel plate normal tensile property of the present invention meets the service requirements of this rank Highrise buildings steel plate completely, and there is larger surplus capacity, 0 DEG C of impact of collision merit is much larger than the 34J of standard-required, Z-direction Tensile fracture shrinking percentage is more than 37%, meet Z35 steel plate rank completely, illustrate that Plate Steel of the present invention has good anti-lamellar tearing ability.Steel plate yield tensile ratio is less than 0.79, and much smaller than 0.85 of standard-required, show that steel plate has excellent shock resistance, steel plate inspection I grade is qualified, and in a word, steel plate of the present invention has excellent comprehensive mechanical performance.Can be applicable to high level, Super High, factories and miness, pylon, large span and large scale structure engineering etc.

The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from principle of the present invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims

1. a low yield strength ratio Q390GJ steel plate for building, yield strength >=390MPa, yield tensile ratio is less than 0.79,0 DEG C of impact of collision merit is greater than 34J, it is characterized in that, the chemical composition of described low yield strength ratio Q390GJ steel plate for building is by weight percentage: C:0.15 ~ 0.17%, Si:0.30 ~ 0.40%, Mn:1.45 ~ 1.55%, P≤0.015%, S≤0.010%, Nb:0.03 ~ 0.04%, V:0.03 ~ 0.04%, Ti:0.01 ~ 0.02%, Als:0.020 ~ 0.040%, and all the other are Fe and impurity.

2. a production method for low yield strength ratio Q390GJ as claimed in claim 1 steel plate for building, is characterized in that, said method comprising the steps of:

Step one is smelted:

Adopt through the pretreated molten iron of desulfurization and high-quality steel scrap as raw material, bottom-blowing of converter adopts omnidistance Argon pattern, the further deoxidation of LF ladle refining furnace, desulfurization, removal is mingled with, adjusting component and temperature, strong according to early stage, mid-term is stronger, the principle formulation Argon curve that later stage is weak, RH operation adopts the dark degasification technique of circulation, the weight percent finally obtaining molten steel is C:0.15 ~ 0.17%, Si:0.30 ~ 0.40%, Mn:1.45 ~ 1.55%, P≤0.015%, S≤0.010%, Nb:0.03 ~ 0.04%, V:0.03 ~ 0.04%, Ti:0.01 ~ 0.02%, Als:0.020 ~ 0.040%, all the other are Fe and impurity,

Step 2 continuous casting:

Step 3 heats;

To plate slab heating in process furnace, heating and temperature control, at 1180 DEG C-1220 DEG C, controls at 200-240min heat-up time;

Step 4 rolling and cooling:

Rolling adopts two-stage control rolling, the i.e. controlled rolling of austenite recrystallization district and austenite non-recrystallization zone controlled rolling, during roughing, start rolling temperature is 1160 ~ 1200 DEG C, the relative draft of single pass has at least more than two passages to control more than 25%, each pass deformation is strictly controlled during finish rolling, finish rolling start rolling temperature≤920 DEG C, open rolling thickness is 1.3-3.0 times of finished product thickness, has twice more than draft >20% at least, end percentage pass reduction >10%, finishing temperature 850-860 DEG C, roll rear steel plate and adopt controlled cooling model, final cooling temperature 660-680 DEG C, obtain the tiny and uniform ferrite+pearlitic structure of crystal grain,

Step 5 finishing and flaw detection.

3. the production method of low yield strength ratio Q390GJ steel plate for building as claimed in claim 2, it is characterized in that, in described method, step 2 is specially:

Continuous caster is straight curved type continuous caster, and adopt the dynamic secondary cooling technology of solidification end dynamic soft-reduction, induction stirring and optimization, by constant temperature, permanent pulling rate technique, final production goes out the thick high-quality continuous casting steel billet of 250mm or 300mm.

4. the production method of low yield strength ratio Q390GJ steel plate for building as claimed in claim 2, it is characterized in that, in described method, step 5 is specially: