CN104630655A - Extra-thick steel plate having excellent balance between strength and toughness and used for welded structure and production process thereof - Google Patents
Extra-thick steel plate having excellent balance between strength and toughness and used for welded structure and production process thereof Download PDFInfo
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Abstract
The invention discloses an extra-thick steel plate having excellent balance between strength and toughness and used for a welded structure. The extra-thick steel plate comprises the following chemical components in percentage by mass: 0.13-0.19% of C, 0.30-0.60% of Si, 1.60-2.00% of Mn, less than or equal to 0.010% of P, less than or equal to 0.002% of S, 0.030-0.070% of Nb, 0.05-0.10% of V, 0.25-0.65% of Cu, 0.20-0.75% of Ni, 0.010-0.045% of Als, 0.0020-0.0080% of Ca, 10-20*10<-4>% of [O] as well as 0.008-0.030% of Ti, less than or equal to 0.15% of Cr, less than or equal to 0.15% of Mo, 0.0005-0.0015% of RE and the balance of Fe and unavoidable impurities, wherein the sum of 2.3C and Mn is equal to or greater than 2.00% and less than or equal to 2.30%; the sum of 2Cr and Mo is equal to or greater than 0.20% and less than or equal to 0.30%; the ratio of Ca to the sum of S and [O] is equal to 1.0-3.0; and the ratio of the sum of Cu and 3.4Cr to Ni is equal to 1.0-2.1. The invention also provides a production process of the extra-thick steel plate having excellent balance between strength and toughness and used for the welded structure. The steel plate is excellent in the balance between strength and toughness and has the characteristics of high strength, high toughness, low yield ratio, good ductility, weldability and hot and -cold processing properties, uniform mechanical properties in the thickness direction and the like. The steel plate can be widely applied in various steel structure works such as construction, offshore platforms, bridges, factories and mine, sports venues and the like.
Description
Technical field
The present invention relates to low-alloy high-strength steel making field, particularly refer to the thick welded construction steel plate of a kind of spy of obdurability good match and production technique thereof.
Background technology
Structural low alloy steel is one of most important structural timber of China, there is high-intensity high-tenacity, good ductility and cold and hot working performance, be widely used in each engineering field of the national economy such as construction industry, ocean platform, pressurized vessel, boiler manfacturing, water/Nuclear power plants, shipbuilding, oil pipeline, bridge, heavy-duty machinery manufacture.Along with the high speed development of national economy and the progress of science and technology, the Important Project such as domestic high-rise building and ultra-large type bridge, power station, ocean platform also get more and more, development also, extra wide, the high-performance future development thick towards spy of its using steel plate, particularly to the demand of super-thick steel plate (more than 100mm) and technical requirements also more and more higher, except requiring that there is high obdurability, also require that there is good anti-lamellar tearing performance, welding property and the mechanical property uniformity along thickness of slab direction.For a long time by China's production technology, the restriction of technical equipment, cause China to produce this type of high strength special heavy plate usually to need to add a large amount of expensive alloying elements, and easily produce banded structure, uneven microstructure on thickness direction, the defects such as the uneven and component segregation of rolling deformation can have a strong impact on the mechanical property of steel, cause conforming product rate not high, quality fluctuation is large, the problem such as welding property difference and through-thickness mechanical heterogeneity still exists simultaneously, be difficult to the quality technology requirement meeting China's super-thick steel plate, cause product competitiveness low, seriously constrain the development and application of China's super-thick steel plate, part large project super-thick steel plate still needs to rely on external import to meet domestic market demand.
Chinese Patent Application No. is the patent documentation of 200810141457.9, it discloses a kind of by quenching+tempering, obtaining thickness is the ultra-thick steel plates of 100 ~ 114mm, but it there is noble element Mo and Cr content is many, not only process costs is high for it, and cost of alloy is also higher; Chinese Patent Application No. be 200810141500.1 and Chinese Patent Application No. be the document of 201010113835.X, also be by adding a large amount of precious alloy Mo, Cr, follow-up employing normalizing+tempering or secondary quenching+tempering obtain ultra-thick steel plates, and its existing problems are that process costs and cost of alloy are all higher; Chinese Patent Application No. is the patent documentation of 200810042124.0,200810141457.9,200810042088.8,200910089346.2 and 201010598123.1 in addition, and all adopt hardening and tempering process to produce, manufacturing process cost is higher.Above-mentioned patented product all due to cost of alloy or manufacturing process cost high and be unfavorable for large-scale promotion application.
Chinese Patent Application No. is the document of 200710054569.6,201010275268.8,200910312460.7,20101028305.3,201010208311.9,201010501298.6,201110176674.3, all adopt normalizing heat treatment technique, but its invention steel grade yield strength is all lower than 400MPa; Also have Chinese Patent Application No. be 200910045452.0 and Chinese Patent Application No. be the document of 201110285075.5, adopt TMCP and controlled rolling process successfully to produce ultra-thick steel plates.But above-mentioned patent does not all do requirement to the homogeneity of thickness direction mechanical property, super-thick steel plate thickness direction mechanical heterogeneity problem all could not be solved.
Summary of the invention
The object of the invention is to overcome the deficiency that the art exists at present, namely super-thick steel plate expensive alloying elements content is high, operational path is complicated, the production cycle is long, intensity rank is low, welding property is poor and the unequal deficiency of through-thickness mechanical property, the thick welded construction steel plate of a kind of spy of obdurability good match and production technique thereof are provided, steel does not need to wait heat treatment step through the modified of complexity, there is manufacturing course simple, with low cost, be easy to the advantage of scale operation.
For achieving the above object, the thick welded construction steel plate of spy of obdurability good match provided by the invention, it is characterized in that: in massfraction, it comprises following chemical composition:
0.13 ~ 0.19%C; 0.30 ~ 0.60%Si; 1.60 ~ 2.00%Mn; P≤0.010%; S≤0.002%; 0.030 ~ 0.070%Nb; 0.05 ~ 0.10%V; 0.25 ~ 0.65%Cu; 0.20 ~ 0.75%Ni; 0.010 ~ 0.045%Als; 0.0020 ~ 0.0080%Ca; 10 ~ 20 × 10
-4% [O]; Also containing 0.008 ~ 0.030%Ti, Cr≤0.15%, Mo≤0.15% and 0.0005 ~ 0.0015%RE, surplus is Fe and inevitable impurity;
Wherein, 2.00%≤2.3C+Mn≤2.30%; 0.20%≤2Cr+Mo≤0.30%; Ca/ (S+ [O])=1.0 ~ 3.0; (Cu+3.4Cr)/Ni=1.0 ~ 2.1.
Present invention also offers a kind of production technique of the thick welded construction steel plate of spy of obdurability good match, it comprises and walks Zou as follows:
(1) carry out dark desulfurization, supplied materials molten iron temperature controls at 1250 ~ 1300 DEG C, S≤0.030%, desulfurization terminal S≤0.0010%;
(2) carry out converter smelting, control to be not less than 1220 DEG C into converter molten iron temperature, hot metal composition Si:0.30 ~ 0.80%, Mn≤0.60%, P≤0.150%, S≤0.0020%, control converter smelting mid point blows number of times and is not more than 2 times, and tapping temperature controls at 1660 ~ 1720 DEG C;
(3) carry out LF refining, ensure that refining time was at 35 ~ 50 minutes, basicity of slag controls 3.3 ~ 3.8;
(4) carry out RH vacuum-treat, control to arrive at a station liquid steel temperature at 1620 ~ 1640 DEG C, the treatment time was at 10 ~ 20 minutes;
(5) pour into a mould, control casting speed at 0.8 ~ 1.0m/min, slab thickness cross dimensions is 300mm;
(6) to strand heating, when strand temperature is below 800 DEG C, heating rate is 7 ~ 9min/cm; When strand temperature is more than 800 DEG C, heating rate is 9 ~ 11min/cm; It is 1240 ~ 1300 DEG C that heating zone temperature controls, at 1200 ~ 1220 DEG C, be incubated 30 ~ 40min, is 240 ~ 300min in stove total heat-up time;
(7) carry out two-stage control rolling: carry out 3 ~ 4 road first stage rollings at 1100 ~ 1150 DEG C, broadening ratio is 1.2 ~ 1.6, and percentage pass reduction is 50 ~ 65%, and end temp is at 1000 ~ 1100 DEG C; Carry out 3 ~ 5 road subordinate phase rollings at austenite Unhydrated cement, control total reduction 45 ~ 55%, finishing temperature is 800 ~ 860 DEG C;
(8) carry out rapid laminar cooling, it is 3 ~ 10 DEG C/s that rate of cooling controls, and final cooling temperature is by 550 ~ 600 DEG C of controls, and the lower water yield and upper water yield Ratio control are 1.1 ~ 1.5; Last air cooling is to room temperature;
(9) carry out normalizing thermal treatment, thermal treatment temp is 880 ~ 920 DEG C, and time inside furnace is [thickness of slab (mm)+30 ~ 50] min, and the type of cooling is the cold or section cooling of mist, and speed of cooling 2 ~ 5 DEG C/s, final cooling temperature is 650 ~ 750 DEG C.
Preferably, in described step (1), supplied materials molten iron temperature is 1300 DEG C; In described step (2), it is 2 times that control converter smelting mid point blows number of times, and tapping temperature is 1720 DEG C; In described step (3), refining time is 50 minutes, and basicity of slag is 3.8; In described step (4), the liquid steel temperature that arrives at a station is 1640 DEG C, and the treatment time is 20 minutes; In described step (5), casting speed is 1.0m/min; In described step (6), when strand temperature is below 800 DEG C, heating rate is 9min/cm; When strand temperature is more than 800 DEG C, heating rate is 11min/cm; Heating zone temperature is 1300 DEG C, at 1220 DEG C of insulation 40min, is 300min in stove total heat-up time; In described step (7), carry out 3 ~ 4 road first stage rollings at 1150 DEG C, broadening ratio is 1.6, and percentage pass reduction is 65%, and end temp is 1100 DEG C; Carry out 3 ~ 5 road subordinate phase rollings at austenite Unhydrated cement, total reduction is 55%, and finishing temperature is 860 DEG C; In described step (8), rate of cooling is 10 DEG C/s, and final cooling temperature is 600 DEG C, and the lower water yield and upper water yield ratio are 1.5; In described step (9), thermal treatment temp is 920 DEG C, and time inside furnace is [thickness of slab (mm)+50] min, and type of cooling section cooling, speed of cooling 5 DEG C/s, final cooling temperature is 750 DEG C.
The reason of principle of work of the present invention and wherein chemical composition limited amount is as follows:
(1) C content of the present invention is selected 0.13 ~ 0.19%, C ensures one of requisite element of armor plate strength, C improves the intensity of steel mainly through gap displacement solution strengthening, also be form tiny Carbonitride Precipitation phase with elements such as Nb, V, thus produce the important element of refined crystalline strengthening and precipitation strength, but C is also one of the chief elements Low Temperature Impact Toughness of Heat-affected Zone being produced to remarkable disadvantageous effect.When C content higher than 0.19% time, increase carbon segregation tendency and M-A island quantity in steel, improve the welding cold crack sensitivity coefficient of steel, reduction base material plasticity and toughness and welding heat influence area toughness, affect the cold and hot working performance of steel; When C content lower than 0.13% time, affect the intensity of steel of the present invention.Therefore C content is defined as 0.13 ~ 0.19%.
(2) Si content of the present invention is selected in steel, to improve intensity at 0.30 ~ 0.60%, Si mainly through solution strengthening.When Si content lower than 0.30% time, its solution strengthening effect to hardness of steel contribution less; When Si content higher than 0.60% time, steel toughness and ductility will be damaged, also can promote that large size M-A island, welded heat affecting zone is separated out, be unfavorable for Low Temperature Impact Toughness of Heat-affected Zone.Therefore Si content is defined as 0.30 ~ 0.60%.
(3) Mn content of the present invention is selected at 1.60 ~ 2.00%, Mn is guarantee steel obdurability and the indispensable element of welded heat affecting zone performance; Mn expands austenite phase field, reduces Ar
3transformation temperature, thinning microstructure in cooling phase-change process and improve intensity and improve low-temperature flexibility; But easily there is macrosegregation in Mn in molten steel solidification process, particularly Mn and C content higher time, the segregation that strand center can be caused serious and loose phenomenon, worsen steel and welding property; Mn too high levels also can form the large sizes such as more manganese sulfide and be mingled with, and reduce the low temperature fracture toughness of steel and the low-temperature flexibility of welded heat affecting zone, therefore Mn content must not higher than 2.00%.When Mn content lower than 1.60% time, cannot hardness of steel be guaranteed.Therefore Mn content is defined as 1.60 ~ 2.00%.
(3) P≤0.010% of the present invention, S≤0.002%, P, S are the detrimental impurity elements in steel.High P easily causes grain boundary segregation, sharply worsens the low-temperature flexibility of steel; S and Mn easily forms MnS and is mingled with, and easily along rolling to formation MnS inclusion band in the operation of rolling, the low-temperature flexibility of severe exacerbation steel, Z-direction performance and welding property, S content need control below 0.002%.
(4) Nb content of the present invention is selected at 0.030 ~ 0.070%, Nb is a kind of carbide, can significantly improve austenite recrystallization temperature, expands rolling technology scope, can make steel rolling and do not damage the mechanical property of steel at relatively high temperatures.In the operation of rolling, the carbonitride particle that Nb is formed in steel, effectively can hinder recrystallize and suppress growing up of austenite crystal, thus fining ferrite grains, improve obdurability and the ductility of steel plate.The carbonitride that Nb also can separate out Nb in process of cooling plays precipitation strength effect.In steel of the present invention, when Nb content lower than 0.030% time, cause yield strength not enough, when Nb content higher than 0.070% time, although the refined crystalline strengthening of Nb and precipitation strength effect increase, but damage rolling equipment when low temperature rolling because intensity is high, too high Nb content is unfavorable for welding property and Low Temperature Impact Toughness of Heat-affected Zone simultaneously.Therefore, Nb content is limited in 0.030 ~ 0.070%.
(5) V content of the present invention is selected 0.050 ~ 0.10%, and the same with Nb, V is also a kind of carbide forming element, also be element important in steel of the present invention, but its effect is weak compared with Nb, but when adding together with Nb, will significantly improve the comprehensive mechanical property of invention steel.In Slow cooling process, V and C combines and forms Carbonitride Precipitation, produces precipitation strength and refined crystalline strengthening effect, improves the intensity of steel and improves toughness.In the special thick steel of the present invention, steel plate top layer due to speed of cooling fast, V carbonitride is not easily separated out, and now V is mainly solid-solution in matrix and produces solution strengthening, but effect is less; And steel plate centre speed of cooling is slow, being suitable for V carbonitride fully separates out, and produces very strong precipitation strength and refined crystalline strengthening effect, improves the intensity in steel plate centre, reduces itself and position, top layer strength difference.But when V content lower than 0.050% time, most of V is solid-solution in matrix, and steel plate centre V Carbonitride Precipitation comparatively small amt, cannot make up the strength difference on centre and top layer; When V content is greater than 0.10%, will have a negative impact to base material and heat affected zone low-temperature flexibility.Therefore, V content is limited in 0.050 ~ 0.10%.
(6) Cu content of the present invention is selected at 0.25 ~ 0.65%, Cu is also one of alloying element important in steel of the present invention.Cu mainly plays solution strengthening and precipitation strength effect in steel, and the addition of C u improves intensity and do not damage impelling strength.Cu also belongs to austenite former, while expansion austenite phase field, also in drawing process, promote austenitic formation and stability.In super-thick steel plate, add the addition of C u can also separate out ε-Cu by self-tempering in Slow cooling process simultaneously, improves steel plate centre intensity.In steel of the present invention, when Cu content lower than 0.25% time, its solution strengthening effect is limited, and simultaneously ε-Cu cannot separate out in self-tempering process, causes undercapacity; When Cu content higher than 0.65% time, can cause hot-short phenomenon, be unfavorable for steel and heat affected zone toughness, simultaneously in self-tempering process, centre will have more ε-Cu to separate out, and cause centre intensity sharply to raise, worsen its toughness and welding property.Therefore, Cu content is limited in 0.25 ~ 0.65%.
(7) Ni content of the present invention is selected at 0.20 ~ 0.75%, Ni little to steel strength contribution, but can obviously improve steel toughness, can also effectively prevent during continuous casting and hot rolling due to surface cracking that Cu brings out.Particularly high to solution strengthening element content such as Cu, Cr steel, its effect improving low-temperature flexibility is just more obvious.Ni amount is too high,
Except increase production cost, surface of steel plate easily produces the iron scale being difficult to come off, and may damage the welding heat influence area toughness of steel.
Als content of the present invention is selected to add in steel at 0.010 ~ 0.045%, Als Chang Zuowei deoxidant element.Als can be combined with N and form tiny AlN particle, improves the intensity of steel and improves toughness.In the present invention, Als can also combine with [O] and form fine oxide particle as organizing forming core core, refinement steel and HAZ tissue.If Als content is lower than 0.010%, above-mentioned effect is not obvious, effectively can not improve steel and HAZ impelling strength, if Als content higher than 0.045% time, easily form the thick oxide inclusion of complicated size, reduce the toughness of steel, worsen welding heat affected impelling strength.
(8) Ca of the present invention is deoxidant element, and be also desulfurization element, its content controls 0.0020 ~ 0.0080%, is the important element in steel of the present invention.Add appropriate Ca in steel by Sulfide inclusion nodularization, ultrafine oxide compound can also be formed as ferrite forming core core in steel, be conducive to the low-temperature flexibility and the HAZ toughness that improve steel.In order to improve its deoxidization desulfuration effect, improve steel product quality and welded heat affecting zone performance, Ca content should be not less than 0.0020%; When Ca content is more than 0.0080%, then can form many larger-size oxide compounds containing Ca and sulfide mixing is mingled with, be unfavorable for the impelling strength of steel and heat affected zone.
(9) O content of the present invention is selected 10 ~ 20 × 10
-4%, generally, O belongs to obnoxious flavour in steel, for guaranteeing the total amount of oxide inclusion in purity of steel and steel, O content strictly need be limited in lower level.But when O content is lower than 10 × 10
-4during %, then in steel, unit surface is not enough as the fine oxide amounts of particles of Ca, Als of forming core core.For avoiding occurring too much oxide-based large size complex inclusion in steel, in steel, O upper content limit is limited in 20 × 10
-4within %.
(10) steel of the present invention also can contain Ti:0.008 ~ 0.030%, Cr≤0.15%, Mo≤0.15% and RE:0.0005 ~ 0.0015%, and surplus is Fe and is inevitably mingled with.
(11) Ti of the present invention selects 0.008 ~ 0.030%, Ti is also a kind of strong carbonitride-forming elements, separate out in steel tiny TiN, Ti (CN) or Nb the composite carbon nitride of Ti, these fine particles effectively can stop Austenite Grain Growth in heating and welding process, improve the low-temperature flexibility of steel.Ti and Nb adds simultaneously, can improve steel austenite recrystallization temperature further, expand rolling technology scope.But when Ti is greater than 0.030%, the carbonitride particle size of the Ti separated out will reach several even tens μm of orders of magnitude, Grain refinement weakens, not obvious to the toughness effect of steel and welded heat affecting zone, when Ti is less than 0.008%, unit surface endoparticle quantity not sufficient, do not have grain refinement effect, therefore Ti is defined as 0.008 ~ 0.030%.
(12) Mo, Cr content of the present invention is all selected in the effect of less than 0.15%, Mo in steel mainly solution strengthening, and a small amount of Mo exists with carbide form.Excessive Mo not only easily obtains a large amount of bainites or martensitic stucture in quick process of cooling, also the martensitic stucture affecting welding heat influence area toughness is easily obtained in welding cooling, be degrading steel and heat affected zone performance, therefore, Mo content must not be greater than 0.15%.Cr is the element effectively improving armor plate strength, also be improve steel hardenability element, ferritic phase apparition is moved to right, the cooling rate widening bainitic transformation is interval, promote the formation of middle temperature transformation tissue, but in steel of the present invention, when Cr content is more than 0.15%, then significantly can reduce steel and heat affected zone toughness.
(13) RE content of the present invention is selected 0.0005 ~ 0.0015%, appropriate RE can control manganese sulfide inclusion thing form, improve the low-temperature flexibility of steel, excessive RE may form large granule and large inclusion group with steel medium sulphide content, the purity of infringement steel, has a negative impact to welded heat affecting zone performance.
Above-mentioned chemical composition also must meet formula simultaneously: 1. 2.00%≤2.3C+Mn≤2.30%, 2. 0.20%≤2Cr+Mo≤0.30%, 3. Ca/ (S+ [O])=1.0 ~ 3.0,4. (Cu+3.4Cr)/Ni=1.0 ~ 2.1.
In the present invention, as 2.3C+Mn < 2.00%, cause hardness of steel not enough, as 2.3C+Mn > 2.30%, containing higher C content in steel, the low-temperature flexibility that its solution strengthening causes declines cannot obtain effectively making up of Ni, causes steel low-temperature flexibility to worsen, and too high C and Mn content is unfavorable for welding heat influence area toughness simultaneously; As 2Cr+Mo < 0.20%, Cu, Cr solution strengthening effect is not obvious, cannot ensure steel strength, as 2Cr+Mo > 0.30%, all has a negative impact to steel and heat affected zone performance; As Ca/ (S+ [O]) < 1.0, the rotten spheroidization of Ca to Sulfide inclusion is not obvious, simultaneously less as the tiny Ca oxide particle of forming core core, during Ca/ (S+ [O]) > 3.0, more larger-size CaO, Al in steel, will be formed
2o
3, CaS, MnS oxide compound and sulfide mixing be mingled with, the low-temperature flexibility of severe exacerbation steel and welding property; For guaranteeing comprehensive mechanical property and the welding property of steel of the present invention, Cu, Cr, Ni massfraction also must meet (Cu+3.4Cr)/Ni=1.0 ~ 2.1.
The production technique of the thick welded construction steel plate of spy of obdurability good match of the present invention, the control of its processing parameter is as follows:
(1) carry out dark desulfurization, supplied materials molten iron temperature controls at 1250 ~ 1300 DEG C, S≤0.030%, desulfurization terminal S≤0.0010%;
(2) carry out converter smelting, control to be not less than 1220 DEG C into converter molten iron temperature, hot metal composition Si:0.30 ~ 0.80%, Mn≤0.60%, P≤0.150%, S≤0.0020%, control converter smelting mid point blows number of times and is not more than 2 times, and tapping temperature controls at 1660 ~ 1720 DEG C;
(3) carry out LF refining, ensure that refining time was at 35 ~ 50 minutes, basicity of slag controls 3.3 ~ 3.8;
(4) carry out RH vacuum-treat, control to arrive at a station liquid steel temperature at 1620 ~ 1640 DEG C, the treatment time was at 10 ~ 20 minutes;
(5) pour into a mould, control casting speed at 0.8 ~ 1.0m/min, slab thickness cross dimensions is 300mm;
(6) to strand heating, when strand temperature is below 800 DEG C, heating rate is 7 ~ 9min/cm; When strand temperature is more than 800 DEG C, heating rate is 9 ~ 11min/cm; It is 1240 ~ 1300 DEG C that heating zone temperature controls, at 1200 ~ 1220 DEG C, be incubated 30 ~ 40min, is 240 ~ 300min in stove total heat-up time;
(7) carry out two-stage control rolling: carry out 3 ~ 4 road first stage rollings at 1100 ~ 1150 DEG C, broadening ratio is 1.2 ~ 1.6, and percentage pass reduction is 50 ~ 65%, and end temp is at 1000 ~ 1100 DEG C; Carry out 3 ~ 5 road subordinate phase rollings at austenite Unhydrated cement, control total reduction 45 ~ 55%, finishing temperature is 800 ~ 860 DEG C;
(8) carry out rapid laminar cooling, it is 3 ~ 10 DEG C/s that rate of cooling controls, and final cooling temperature is by 550 ~ 600 DEG C of controls, and the lower water yield and upper water yield Ratio control are 1.1 ~ 1.5; Last air cooling is to room temperature;
(9) carry out normalizing thermal treatment, thermal treatment temp is 880 ~ 920 DEG C, and time inside furnace is [thickness of slab (mm)+30 ~ 50] min, and the type of cooling is the cold or section cooling of mist, and speed of cooling 2 ~ 5 DEG C/s, final cooling temperature is 650 ~ 750 DEG C.
The invention has the advantages that: steel plate of the present invention does not need to add the noble metals such as a large amount of Mo, Cr, production technique is simple, utilizes 100 ~ 120mm super-thick steel plate of explained hereafter of the present invention to have high strength (R
eL>=400MPa), high tenacity (KV at-20 DEG C
2>=120J), the feature such as low yield strength ratio (≤0.75), good ductility, welding property and cold and hot working performance, thickness direction mechanical property be even.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in further detail.
The production technique of the thick welded construction steel plate of spy of obdurability good match of the present invention, concrete steps are as follows:
(1) carry out dark desulfurization, supplied materials molten iron temperature controls at 1250 ~ 1300 DEG C, S≤0.030%, desulfurization terminal S≤0.0010%;
(2) carry out converter smelting, control to be not less than 1220 DEG C into converter molten iron temperature, hot metal composition Si:0.30 ~ 0.80%, Mn≤0.60%, P≤0.150%, S≤0.0020%, control converter smelting mid point blows number of times and is not more than 2 times, and tapping temperature controls at 1660 ~ 1720 DEG C;
(3) carry out LF refining, ensure that refining time was at 35 ~ 50 minutes, basicity of slag controls 3.3 ~ 3.8;
(4) carry out RH vacuum-treat, control to arrive at a station liquid steel temperature at 1620 ~ 1640 DEG C, the treatment time was at 10 ~ 20 minutes;
(5) pour into a mould, control casting speed at 0.8 ~ 1.0m/min, slab thickness cross dimensions is 300mm;
(6) to strand heating, when strand temperature is below 800 DEG C, heating rate is 7 ~ 9min/cm; When strand temperature is more than 800 DEG C, heating rate is 9 ~ 11min/cm; It is 1240 ~ 1300 DEG C that heating zone temperature controls, at 1200 ~ 1220 DEG C, be incubated 30 ~ 40min, is 240 ~ 300min in stove total heat-up time;
(7) carry out two-stage control rolling: carry out 3 ~ 4 road first stage rollings at 1100 ~ 1150 DEG C, broadening ratio is 1.2 ~ 1.6, and percentage pass reduction is 50 ~ 65%, and end temp is at 1000 ~ 1100 DEG C; Carry out 3 ~ 5 road subordinate phase rollings at austenite Unhydrated cement, control total reduction 45 ~ 55%, finishing temperature is 800 ~ 860 DEG C;
(8) carry out rapid laminar cooling, it is 3 ~ 10 DEG C/s that rate of cooling controls, and final cooling temperature is by 550 ~ 600 DEG C of controls, and the lower water yield and upper water yield Ratio control are 1.1 ~ 1.5; Last air cooling is to room temperature.
(9) carry out normalizing thermal treatment, thermal treatment temp is 880 ~ 920 DEG C, and time inside furnace is [thickness of slab (mm)+30 ~ 50] min, and the type of cooling is the cold or section cooling of mist, and speed of cooling 2 ~ 5 DEG C/s, final cooling temperature is 650 ~ 750 DEG C.
Below: table 1 is various embodiments of the present invention and the list of comparative example chemical composition value; Table 2 is various embodiments of the present invention and the list of comparative example main technologic parameters value; Table 3 is the mechanical property test result of the embodiment of the present invention.
The chemical composition of table 1 steel plate of the present invention and compared steel contrasts (wt, %) (one)
The chemical composition of table 1 steel plate of the present invention and compared steel contrasts (wt, %) (two)
The main technologic parameters list of table 2 various embodiments of the present invention and comparative example
The mechanical property test result of table 3 various embodiments of the present invention
Through carrying out normal tensile property ,-20 DEG C of impact of collision tests to steel plate top layer of the present invention, thickness of slab 1/4 place and the sampling of thickness of slab 1/2 place, and contrast with compared steel, its result: yield strength and the compared steel of steel plate surface location of the present invention are in same level, and tensile strength ratio, unit elongation and impelling strength are all better than compared steel, and steel plate of the present invention has lower yield tensile ratio; The surrender at thick 1/4 place of steel plate of the present invention and thickness of slab 1/2 place and tensile strength and unit elongation, impelling strength level are apparently higher than compared steel.In a word, steel plate obdurability of the present invention coupling is excellent, the feature such as have high strength, high tenacity, low yield strength ratio, good anti-lamellar tearing performance and ductility and thickness direction mechanical property is even.Intensity and the toughness index of the different sampling point of what is more important steel plate of the present invention are in same level, and the performance level of the different sampling point of the steel plate of comparative example differs greatly, show as by top layer through-thickness to centre, its intensity and toughness index obviously reduce, and obvious steel plate through-thickness mechanical property uniformity of the present invention is better.
The obdurability coupling of the special thick welded construction steel plate of the 100 ~ 120mm produced according to steel plate composition of the present invention and production technique is excellent, has the features such as high strength, high tenacity, low yield strength ratio, good ductility, welding property and cold and hot working performance, thickness direction mechanical property are even.The present invention is of many uses, can be applicable to the various Steel Structure Works such as building, ocean platform, bridge, factories and miness and stadiums.
Claims (3)
1. the thick welded construction steel plate of the spy of obdurability good match, it is characterized in that: in massfraction, it comprises following chemical composition:
0.13 ~ 0.19%C; 0.30 ~ 0.60%Si; 1.60 ~ 2.00%Mn; P≤0.010%; S≤0.002%; 0.030 ~ 0.070%Nb; 0.05 ~ 0.10%V; 0.25 ~ 0.65%Cu; 0.20 ~ 0.75%Ni; 0.010 ~ 0.045%Als; 0.0020 ~ 0.0080%Ca; 10 ~ 20 × 10
-4% [O]; Also containing 0.008 ~ 0.030%Ti, Cr≤0.15%, Mo≤0.15% and 0.0005 ~ 0.0015%RE, surplus is Fe and inevitable impurity;
Wherein, 2.00%≤2.3C+Mn≤2.30%; 0.20%≤2Cr+Mo≤0.30%; Ca/ (S+ [O])=1.0 ~ 3.0; (Cu+3.4Cr)/Ni=1.0 ~ 2.1.
2. produce a method for the thick welded construction steel plate of spy of obdurability good match as claimed in claim 1, it comprises and walks Zou as follows:
(1) dark desulfurization is carried out: supplied materials molten iron temperature controls at 1250 ~ 1300 DEG C, S≤0.030%, desulfurization terminal S≤0.0010%;
(2) converter smelting is carried out: control to be not less than 1220 DEG C into converter molten iron temperature, Si:0.30 ~ 0.80% in hot metal composition, Mn≤0.60%, P≤0.150%, S≤0.0020%, control converter smelting mid point blows number of times and is not more than 2 times, and tapping temperature controls at 1660 ~ 1720 DEG C;
(3) LF refining is carried out: ensure that refining time was at 35 ~ 50 minutes, basicity of slag controls 3.3 ~ 3.8;
(4) RH vacuum-treat is carried out: control to arrive at a station liquid steel temperature at 1620 ~ 1640 DEG C, the treatment time was at 10 ~ 20 minutes;
(5) pour into a mould: control casting speed at 0.8 ~ 1.0m/min, slab thickness cross dimensions is 300mm;
(6) heat strand: when strand temperature is below 800 DEG C, heating rate is 7 ~ 9min/cm; When strand temperature is more than 800 DEG C, heating rate is 9 ~ 11min/cm; It is 1240 ~ 1300 DEG C that heating zone temperature controls, at 1200 ~ 1220 DEG C, be incubated 30 ~ 40min, is 240 ~ 300min in stove total heat-up time;
(7) carry out two-stage control rolling: carry out 3 ~ 4 road first stage rollings at 1100 ~ 1150 DEG C, broadening ratio is 1.2 ~ 1.6, and percentage pass reduction is 50 ~ 65%, and end temp is at 1000 ~ 1100 DEG C; Carry out 3 ~ 5 road subordinate phase rollings at austenite Unhydrated cement, control total reduction 45 ~ 55%, finishing temperature is 800 ~ 860 DEG C;
(8) carry out rapid laminar cooling: it is 3 ~ 10 DEG C/s that rate of cooling controls, final cooling temperature is by 550 ~ 600 DEG C of controls, and the lower water yield and upper water yield Ratio control are 1.1 ~ 1.5; Last air cooling is to room temperature;
(9) carry out normalizing thermal treatment: thermal treatment temp is 880 ~ 920 DEG C, time inside furnace is [thickness of slab (mm)+30 ~ 50] min, and the type of cooling is the cold or section cooling of mist, and speed of cooling 2 ~ 5 DEG C/s, final cooling temperature is 650 ~ 750 DEG C.
3. the production technique of the thick welded construction steel plate of the spy of obdurability good match according to claim 2, is characterized in that:
In described step (1), supplied materials molten iron temperature is 1300 DEG C;
In described step (2), it is 2 times that control converter smelting mid point blows number of times, and tapping temperature is 1720 DEG C;
In described step (3), refining time is 50 minutes, and basicity of slag is 3.8;
In described step (4), the liquid steel temperature that arrives at a station is 1640 DEG C, and the treatment time is 20 minutes;
In described step (5), casting speed is 1.0m/min;
In described step (6), when strand temperature is below 800 DEG C, heating rate is 9min/cm; When strand temperature is more than 800 DEG C, heating rate is 11min/cm; Heating zone temperature is 1300 DEG C, at 1220 DEG C of insulation 40min, is 300min in stove total heat-up time;
In described step (7), carry out 3 ~ 4 road first stage rollings at 1150 DEG C, broadening ratio is 1.6, and percentage pass reduction is 65%, and end temp is 1100 DEG C; Carry out 3 ~ 5 road subordinate phase rollings at austenite Unhydrated cement, total reduction is 55%, and finishing temperature is 860 DEG C;
In described step (8), rate of cooling is 10 DEG C/s, and final cooling temperature is 600 DEG C, and the lower water yield and upper water yield ratio are 1.5;
In described step (9), thermal treatment temp is 920 DEG C, and time inside furnace is [thickness of slab (mm)+50] min, and type of cooling section cooling, speed of cooling 5 DEG C/s, final cooling temperature is 750 DEG C.
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| CN108546866A (en) * | 2018-04-04 | 2018-09-18 | 首钢集团有限公司 | A kind of production method of 690MPa grade high ductilities structural steel |
| CN109868342A (en) * | 2019-03-28 | 2019-06-11 | 北京科技大学 | A method of carbon equivalent high steel plate welding heat influence area toughness is improved using rare earth |
| CN109930070A (en) * | 2019-03-28 | 2019-06-25 | 北京科技大学 | A method of low-carbon-equivalent steel plate welding heat influence area toughness is improved using rare earth |
| CN110052500A (en) * | 2019-03-15 | 2019-07-26 | 舞阳钢铁有限责任公司 | A kind of production method of controlled rolling type ultra-wide steel plate |
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