CN101289728B - Low-yield ratio, high heat input welding, high-strength and high ductility steel plate and method of manufacture - Google Patents
Low-yield ratio, high heat input welding, high-strength and high ductility steel plate and method of manufacture Download PDFInfo
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Abstract
The invention provides a steel plate having low-temperature toughness, high tensile strength and low yield ratio, as well as a method for making the same. By combining simple combination design of alloying elements with optimized TMCP process, the method successfully solves the problem that low-temperature impact toughness and low yield ratio are in mutual conflict and difficult to reconcile in composition design and process design, which reduces the amount of steel material, saves cost, lightens the dead weight of a steel structure, increases stability and safety, and more importantly, improves the safety, stability and seismic damage resistance of the steel structure. The steel plate can be widely applied to large-scale high-rise building structures, bridge structures, offshore oil production platform structures, low temperature pressure vessels and large-scale ship structures.
Description
Technical field
The present invention relates to the steel plate materials technology, particularly, the present invention relates to low-carbon and low-alloy steel plate materials technology, more specifically, but the present invention relates to large-line energy welding low yield strength ratio steel plate and manufacture method thereof.
Background technology
As everyone knows, low-carbon (LC) (high strength) low alloy steel is one of most important structural timber, is widely used among petroleum natural gas pipeline, ocean platform, shipbuilding, bridge structure, pressurized vessel, building structure, automotive industry, transportation by railroad and the machinofacture.Low-carbon (LC) (high strength) low alloy steel performance depends on the process system of its chemical ingredients, manufacturing processed, and wherein intensity, toughness and weldability are the most important performances of low-carbon (LC) (high strength) low alloy steel, and its final decision is in the microstructure state of finished steel.Continuous development along with science and technology, people propose higher requirement to obdurability, the weldability of steel, promptly when keeping low manufacturing cost, improve the comprehensive mechanical performance and the use properties of steel plate significantly, promptly reduce the consumption of steel and save cost, alleviate the own wt of steel construction, what is more important is further to improve steel construction security and stability and antiseismic destructiveness, requires low yield strength ratio, and promptly yield tensile ratio is controlled at below 0.85.Started the research climax that develops high-performance steel iron material of new generation in the world wide at present, obtain better tissue coupling by alloy combination design optimization and innovation TMCP Technology, thereby obtain higher obdurability, lower yield tensile ratio, better weldability.
Prior art is when making yield strength 〉=415MPa ,-40 ℃ the Plate Steel of low-temperature impact toughness 〉=47J, generally in steel, add a certain amount of Ni or Cu+Ni element (The Firth (1986) international Symposiumand Exhibit on Offshore Mechanics andArctic Engineering, 1986, Tokyo, Japan, 354; " DEVELOPMENTS IN MATERIALS FOR ARCTIC OFFSHORE STRUCTURES "; " Structural Steel Plates for Arctic Use Produced by Multipurpose Accelerated CoolingSystem " (Japanese), Kawasaki Steel skill newspaper, 1985, No.168～72; " Application of Accelerated CoolingFor Producing 360MPa Yield Strength Steel plates of up to 150mm in Thickness with LowCarbon Equivalent ", Accelerated Cooling Rolled Steel, 1986,209～219; " High StrengthSteel Plates For Ice-Breaking Vessels Produced by Thermo-Mechanical ControlProcess ", Accelerated Cooling Rolled Steel, 1986,249～260; " 420MPa Yield Strength SteelPlate with Superior Fracture Toughness for Arctic Offshore Structures ", Kawasaki steeltechnical report, 1999, No.40,56; " 420MPa and 500MPa Yield Strength Steel Plate withHigh HAZ toughness Produced by TMCP for Offshore Structure ", Kawasaki steel technicalreport, 1993, No.29,54; " Toughness Improvement in Bainite Structure byThermo-Mechanical Control Process " (Japanese) Sumitomo Metal Industries, Vol.50, No.1 (1998), 26; " the offshore platform structure steel plate that ice Haiti district uses " (Japanese), steel research, 1984, No. 314,19～43), to guarantee that the mother metal steel plate has excellent low-temperature flexibility, but shortcoming is that the steel plate tensile strength of coming out with mentioned component system and fabrication process is generally lower, general all can not reach 610MPa, and the yield strength of steel plate is generally higher, cause steel plate yield tensile ratio very high (reach more than 0.85, even higher), constitute potential threat the security and stability of steel construction and antiseismic ripple are destructive.Existing a large amount of patent documentations just illustrate the low-temperature flexibility that how to realize the mother metal steel plate, just improve the big linear energy weldability of steel plate, it is less to obtain good welded heat affecting zone HAZ low-temperature flexibility explanation, more do not relate to how when improving steel plate tensile strength, reduce the yield strength of steel plate, promptly reduce the yield tensile ratio (clear 63-93845, clear 63-79921, clear 60-258410, special flat 4-285119, special flat open 4-308035, flat 3-264614, flat 2-250917, flat 4-143246, US patent 4855106, US patent 5183198, the US patent 4137104 opened) of steel plate.The yield tensile ratio that present reduction 60 kg class reaches with upper steel plate all adopts secondary quenching+tempering process, i.e. RQ+Q '+T (CAMP-ISIJ, 1 (1988), P813; Iron と steel, 73 (1987), S345; CAMP-ISIJ, 4 (1991), P1948; Sumitomo Metal Industries, 40 (1988), P279; CAMP-ISIJ, 1 (1988), P527) and DQ+Q '+T (CAMP-ISIJ, 1 (1988), P814; Iron と steel, 73 (1987), S1312; CAMP-ISIJ, 1 (1988), P817; CAMP-ISIJ, (1988), P1779), wherein DQ---direct quenching, RQ---reheat quenches, and Q '---austenite/ferrite two-phase region quenches, T---tempering.Though can reduce the yield tensile ratio of steel plate significantly with aforesaid method, the low-temperature flexibility level of steel plate far can not reach the requirement of-40 ℃ of ballistic work 120J, steel plate can not bear the large-line energy welding simultaneously.
The present inventor is by constantly groping, solved low-temperature impact toughness and low yield strength ratio conflict, are difficult to mediation mutually in the design of composition design and processes problem, and this difficult point of maintenance welded heat affecting zone HAZ excellent in low temperature toughness, the gained steel plate has higher obdurability, lower yield tensile ratio, better weldability, thereby has finished the present invention.
But first purpose of the present invention provides a kind of low yield strength ratio large-line energy welding high-strength and high-ductility steel plate.But second purpose of the present invention provides a kind of preparation method of low yield strength ratio large-line energy welding high-strength and high-ductility steel plate.
Summary of the invention
But first aspect of the present invention provides a kind of low yield strength ratio large-line energy welding high-strength and high-ductility steel plate, described steel plate comprises following component: C:0.025%～0.055%, Si :≤0.20%, Mn:1.40%～1.75%, P :≤0.013%, S :≤0.002%, Cu:0.25%～0.55%, Ni:0.40%～0.80%, Mo:0.10%～0.40%, Nb:0.020%～0.040%, Als:0.040%～0.060%, Ti:0.007%～0.013%, N :≤0.0040%, Ca:0.001%～0.005%, B :≤0.0003%; And above-mentioned constituent content must satisfy following relation: 25≤Mn/C≤55,3.0≤Ti/N≤4.0 simultaneously, Ni/Cu 〉=1.5, and Ti/Nb is 0.30～1.0, and Ca/S is 0.80～3.0; Surplus is iron and unavoidable impurities.
Specifically, composition design metallurgy is analyzed as follows in detail:
C is very big to intensity, low-temperature flexibility and the weldability influence of steel, from low-temperature flexibility and the weldability of improving steel, wishes that C content is controlled lowlyer in the steel; But microstructures Control angle from the intensity of steel and manufacturing process, C content should not be low excessively, and low excessively C content (＜0.025%) not only causes Ac
1, Ac
3, Ar
1, Ar
3The point temperature is higher, and austenite and ferrite crystal grain coarsening rate are too high, bring very big difficulty to grain refining, form mixed grain structure easily, cause the low and serious deterioration of ultra-large linear energy input welded heat affecting zone low-temperature flexibility of steel low-temperature flexibility, so C content lower control limit should not be lower than 0.025% in the steel; When C content improves, though help the steel plate microstructure thinning, damage the weldability of steel plate, especially under the large-line energy welding conditions; Because the speed of cooling in serious alligatoring of heat affected zone (HAZ) crystal grain and the Thermal Cycle process of cooling is very slow, (HAZ) easily forms thick ferrite side plate bar (FSP), Widmannstatten structure (WF), upper bainite abnormal structures such as (Bu) in the heat affected zone, and M-A island quantity increases, size increases the toughness of grievous injury heat affected zone (HAZ); During the C too high levels, suppress acicular ferrite AF and form in the what is more important steel, promote upper bainite Bu to form, cause can not get the acicular ferrite microstructure, so C content should not be higher than 0.055%.
Mn as most important alloying element in steel except that the intensity that improves steel plate, also have the austenite of expansion phase region, reduce Ar
3Point temperature, refinement ferrite crystal grain and improve the steel plate low-temperature flexibility effect, promote low temperature phase change tissue to form and the effect of raising armor plate strength; Therefore adopt TMCP technology to make the steel plate of tensile strength 〉=610MPa, internal control Mn content can not be lower than 1.40% in the steel.Segregation takes place in Mn easily in the molten steel solidification process, especially too high Mn content (when Mn content＞1.75%), not only can cause the continuous casting operational difficulty, and easily and element generation conjugation segregation phenomenas such as C, P, S, the segregation that increases the weight of the continuously cast bloom center is with loose, and serious continuously cast bloom center segregation easily forms abnormal structure in follow-up controlled rolling and welding process; Simultaneously, the Mn too high levels also can form thick MnS particle, roll to extension on this thick MnS particle edge in course of hot rolling, the impelling strength of severe exacerbation mother metal steel plate (especially horizontal), welded heat affecting zone (HAZ) (especially under the large-line energy welding conditions) causes Z to low, the anti-lamellar tearing poor performance of performance; In addition, cross hardenability that high Mn content also can improve steel, improve welding cold crack sensitivity coefficient (Pcm) in the steel, the weldprocedure that influence steel (when less heat input welds, easily forms crisp sclerous tissues such as martensite; When bigger heat input welds, easily form thick upper bainite).Therefore, the upper limit of Mn content can not surpass 1.75% in the steel.For guaranteeing that fracture transition temperature Tris. is lower than-60 ℃, the content ratio of Mn and C should be controlled between 25～55.
Si promotes deoxidation of molten steel and can improve armor plate strength, but adopt the molten steel of Al deoxidation, the desoxydatoin of Si is little, though Si can improve the intensity of steel plate, but the low-temperature flexibility and the weldability of Si grievous injury steel plate, especially under the large-line energy welding conditions, Si not only promotes the M-A island to form, and the M-A island size that forms is big, skewness, the toughness of grievous injury welded heat affecting zone (HAZ), therefore the Si content in the steel should be controlled lowly as far as possible, considers the economy and the operability of steelmaking process, and Si content is controlled at below 0.20%.
P is as harmful mechanical property that is mingled with steel in the steel, especially low-temperature impact toughness and weldability have huge detrimental effect, it is low more good more to require in theory, but consider steel-making operability and steel-making cost, but for requiring large-line energy welding ,-60 ℃ of flexible steel plates, P content need be controlled at≤and 0.013%.
S has very big detrimental effect as harmful low-temperature flexibility that is mingled with steel in the steel, the more important thing is that S combines with Mn in steel, form the MnS inclusion, in course of hot rolling, the plasticity-of MnS makes MnS along rolling to extension, form along rolling to MnS inclusion band, the transverse impact toughness of grievous injury steel plate, Z are to performance and weldability, and S produces hot short principal element in the course of hot rolling simultaneously.It is low more good more to require in theory, but considers steel-making operability, steel-making cost and the smooth and easy principle of logistics, but for the steel plate that requires-60 ℃ of toughness large-line energies welding, S content need be controlled at≤0.002%.
Ni is unique element that can improve the intensity and the low-temperature flexibility of steel plate, adds Ni in the steel and can reduce Ar
3The point temperature, improve the hardening capacity of steel plate, Ni can also reduce the copper brittleness phenomenon of Copper Bearing Steel, alleviates the intergranular cracking of course of hot rolling, therefore Ni/Cu 〉=1.50, this also is one of stable prerequisite that obtains high-strength, high-ductility and low yield strength ratio acicular ferrite steel of composition of steel system of the present invention; Ni can also improve the resistance to atmospheric corrosion of steel plate; Therefore theoretically, Ni content is high more within the specific limits good more in the steel, the welded heat affecting zone but too high Ni content can harden, weldability to steel plate is unfavorable, Ni is a kind of very noble element simultaneously, consider that from the ratio of performance to price Ni content is controlled between 0.40%～0.80%, do not damage the weldability of steel plate with the intensity of the hardening capacity of guaranteeing steel plate and steel plate, low-temperature flexibility.Add Cu and also can reduce Ar
3The point temperature improves the hardening capacity of steel plate and the resistance to atmospheric corrosion of steel plate; But the Cu addition is too much, is higher than 0.55%, causes copper brittleness, cc billet surface quality and implosion problem easily; The Cu addition is very few, is lower than 0.25%, cuts little ice.Therefore Cu content is controlled between 0.25%～0.55%; The compound interpolation of Cu, Ni except that the copper brittleness phenomenon that reduces Copper Bearing Steel, alleviate the effect of intergranular cracking of course of hot rolling, the more important thing is that Cu, Ni are austenite stabilizer element, the compound interpolation of Cu, Ni can reduce Ar significantly
3Improve the motivating force of austenite to ferrite transformation, cause ferrite lath to grow up to all directions, cause between ferrite lath the position to become big (extreme case forms the acicular ferrite structure that is all high-angle boundary between ferrite lath down) to difference, under the effect of Nb, Mo and recrystallization zone controlled rolling effect, suppress upper bainite and form, promote acicular ferrite to form, when improving steel plate tensile strength and low-temperature flexibility, reduce the yield tensile ratio of steel plate.
Mo can greatly improve the hardening capacity of steel plate, promotes the low temperature phase change tissue, improves the tensile strength of steel plate, and Mo promotes acicular ferrite to form under the effect of non-recrystallization controlled rolling effect in addition; But the Mo addition is lower than at 0.10% o'clock, and role is less, and the Mo addition was above 0.40% o'clock, not only increase the manufacturing cost of steel plate, the more important thing is the weldability of infringement steel plate, the production cost of especially large-line energy welded heat affecting zone HAZ toughness, and increase steel plate.Therefore Mo content is controlled between 0.10%～0.50%.
Nb: the Nb element purpose of adding trace in the steel is the formation of carrying out the non-recrystallization controlled rolling and promoting the low temperature phase change tissue, be no more than 0.055% for the C upper content limit, when the Nb addition is lower than 0.020%, not only can not bring into play effective controlled rolling effect, and solid solution Nb content also reduces in the steel, and influence and Mo elements compounding promote the effect of acicular ferrite; When the Nb addition surpasses 0.040%, bring out upper bainite (Bu) formation and secondary under the large-line energy welding conditions and separate out embrittling effect, the low-temperature flexibility of grievous injury large-line energy welded heat affecting zone (HAZ), therefore Nb content is controlled between 0.020%～0.040%, when obtaining the formation of best controlled rolling effect and acicular ferrite, do not damage the toughness of large-line energy welded H AZ again.
The span of control of N is corresponding with the span of control of Ti, and for the ultra-large linear energy input welding steel, Ti/N is best between 3.0～4.0.N content is low excessively, and generation TiN number of particles is few, size is big, can not play the effect of the weldability of improving steel, and is harmful to weldability on the contrary; But during the N too high levels, free [N] increases in the steel, and especially heat affected zone (HAZ) free [N] content sharply increases under the large-line energy welding conditions, grievous injury HAZ low-temperature flexibility, the weldability of deterioration steel.Therefore N content is controlled at below 0.0040%.
Add trace Ti in the steel, purpose is to combine with N in the steel, generates the very high TiN particle of stability, and inhibition welded H AZ district austenite crystal is grown up and changed the second-order phase transition product, improves the weldability of steel and the low-temperature flexibility of HAZ.The Ti content that adds in the steel will contain flux matched with the N in the steel, and the principle of coupling is that TiN can not separate out in liquid molten steel and must separate out in solid phase; Therefore TiN separate out temperature must guarantee to be lower than 1400 (, according to log[Ti] [N]=-16192/T+4.72 can determine the add-on of Ti.When adding Ti content very few (＜0.007%), form TiN number of particles deficiency, the austenite crystal that is not enough to suppress HAZ is grown up and is changed the second-order phase transition product and improve the low-temperature flexibility of HAZ; When adding Ti content too much (＞0.012%), TiN separates out temperature and surpasses 1400 ℃, in the solidification of molten steel process, may also separate out large size TiN particle, this large size TiN particle not only can not suppress the austenite crystal of HAZ grows up, and becomes the starting point of crack initiation on the contrary; Therefore the optimum controling range of Ti content is 0.007%～0.0130%.
Als in the steel is the freedom [N] in the steel fixedly, reduces welded heat affecting zone (HAZ) free [N], improve the low-temperature flexibility effect of large-line energy welded H AZ, so the Als lower limit is controlled at 0.040%; Not only can cause the casting difficulty but add excessive Als in the steel, and can in steel, form the needle-like Al of a large amount of disperses
2O
3Inclusion, infringement steel plate endoplasm viability, low-temperature flexibility and weldability, so the Als upper limit is controlled at 0.060%.
Steel is carried out Ca to be handled, on the one hand can further pure molten steel, on the other hand sulfide in the steel is carried out denaturing treatment, make it to become non deformable, stablize tiny spherical sulfide, suppress the red brittleness of S, the low-temperature flexibility that improves steel and Z to performance, improve steel plate flexible anisotropy.What of Ca add-on are depended on the height of S content in the steel, and the Ca add-on is low excessively, and treatment effect is little; The Ca add-on is too high, and (O, S) oversize, fragility also increases, and can become the fracture crack starting point, reduces the low-temperature flexibility of steel, also reduces purity of steel simultaneously, pollutes molten steel to form Ca.General control Ca content is pressed ESSP=(wt%Ca) [1-1.24 (wt%O)]/1.25 (wt%S), and wherein ESSP is a sulfide inclusion shape control index, be advisable between the span 0.5～5, so the OK range of Ca content is 0.0010%～0.0050%.
For guaranteeing to form the acicular ferrite microstructure, the remaining B content in the steel is necessary≤and 0.0003%.
Be heat affected zone (HAZ) low-temperature flexibility of guaranteeing the large-line energy welding steel, carbon equivalent IIW≤0.42%, welding cold cracking Sensitivity Index Pcm≤0.20%; IIW=wt%C+wt%Mn/6+ (wt%Cu+wt%Ni)/15+ (wt%Cr+wt%Mo+wt%V)/5 wherein, Pcm=wt%C+wt%Si/30+ (wt%Mn+wt%Cu+wt%Cr)/20+wt%Ni/60+wt%Mo/15+wt%V/10+5wt%B.
But another aspect of the present invention provides the preparation method of low yield strength ratio large-line energy welding high-strength and high-ductility steel plate, may further comprise the steps:
1) continuous casting: pouring temperature≤1540 ℃;
2) hot rolling: slab carries out quick continuous rolling in 1070 ℃～1130 ℃ low-temperature heats in the perfect recrystallization district, carries out controlled rolling in the non-recrystallization district;
3) controlled chilling: pass and to put time≤60 second, quicken to be cooled to 450 ℃～600 ℃ with the speed of 〉=10 ℃/s earlier, then slowly cooling and/or natural air cooling to room temperature.
Specifically, find after deliberation: Hi-Stren steel Charpy impact transition temperature Trs. changes a lot to the susceptibility of the grain-size difference with the microstructure type, Charpy impact transition temperature Trs. to the microstructure susceptibility by height to low order is: high carbon martensite/bainite, low carbon martensite/bainite, ferrite/perlite, promptly when microstructure was high carbon martensite/bainite, Charpy impact transition temperature Trs. sharply rose with the increase of grain-size; When microstructure was low carbon martensite/bainite, Charpy impact transition temperature Trs. rose with fast speeds with the increase of grain-size; When microstructure was ferrite/perlite, Charpy impact transition temperature Trs. was relatively slow with the increase lift velocity of grain-size; But when microstructure thinning when to a certain degree (reaching 10 μ m), high carbon martensite/bainite structure, low carbon martensite/bainite structure and ferrite/pearlitic structure Charpy impact transition temperature Trs. arrives par with the variation of grain-size.For obtaining good low-temperature impact toughness, the microstructure size must be tiny and even; According to acicular ferrite (bainite)/martensitic transformation the original austenite grain degree is had very strong heredity, original austenite grain was tiny of 10～15 μ m and even (this is difficult to accomplish) before this just required bainitic transformation; And for not too uniform original austenite grain, must adopt strong low temperature controlled rolling, to form a large amount of deformed belts, mechanical twin band and dislocation tangling point, the broken original austenite grain of deformation and increase the ferrite lath nucleation site and the ferrite lath obstacle of growing up at utmost.Therefore, in steel, contain microalloy elements such as Ti, Nb, and 1100 ℃ of low-temperature heats of slab employing, can guarantee that the slab original austenite grains is tiny, lay the foundation for finally the steel plate microstructure is tiny; Adopt the strong controlled rolling process of low temperature, guarantee to have a large amount of strain accumulations in the steel plate, form a large amount of dislocation, deformed belt, and producing a large amount of steps on the original austenite crystal prevention, on the twin boundary, these steps and intracrystalline dislocation tangling are put the nucleation site of ferrite lath not only but also are the obstacles that ferrite lath is grown up, in with after-acceleration cooling phase-change process, greatly refinement the steel plate microstructure.
TMCP technological design scheme of the present invention is: recommend to adopt continuous casting process, and continuous casting process emphasis control pouring temperature, tundish molten steel casting temperature≤1540 ℃, the low temperature teeming practice is better, with the original as-cast structure of refinement.For the center Mn segregation of control continuously cast bloom, adopt induction stirring or continuously cast bloom gently to depress technology; When employing was gently depressed technology, light draught was controlled between 5%～10%.
Tiny for guaranteeing the initial austenite uniform crystal particles, when must adopt slab low-temperature heat technology, also to guarantee the complete solid solution of micro alloying element Nb, slab heating temperature is controlled between 1070 ℃～1130 ℃, 1100 ℃ of target Heating temperatures are guaranteed the evenly tiny and complete solid solution of microalloy element Nb of original slab autstenitic grain size.
In the perfect recrystallization temperature range, adopt big rolling pass draft to carry out quick continuous rolling, guarantee that refine austenite crystal grain takes place dynamically/static recrystallize the deformation metal; For this reason, rolling pass draft 〉=12%, recrystallization zone (〉=1000 ℃) accumulative total draft 〉=50%; Carry out controlled rolling in the non-recrystallization district, percentage pass reduction 〉=8%, non-recrystallization cold zone (≤850 ℃) accumulative total draft 〉=60%, finishing temperature is controlled between 760 ℃～800 ℃.
Should control shortly as far as possible from rolling the end to the biography time of putting beginning to quicken to cool off, strive being controlled in 60 seconds, be cooled to the speed of 〉=10.0 ℃/s and stop cold temperature, stopping cold temperature range be 450 ℃～600 ℃; The natural air cooling of back below the steel plate slow cooling to 100 of thickness 〉=40mm subsequently ℃ is to room temperature, and steel plate must not be lower than 24 hours 〉=300 ℃ slow cooling time, and the steel plate natural air cooling of thickness＜40mm is to room temperature.
Beneficial effect:
The present invention has adopted the composition system of the high Mn-of low-carbon (LC) C-(Nb+Ti) micro-alloyed steel as the basis, control carbon equivalent IIW≤0.42%, cold crack sensitivity coefficient Pcm≤0.20%, suitably improve the content of sour molten Als, control Mn/C is than between 25～55, (Cu+Ni+Mo) alloying and Ni/Cu 〉=1.5, (Ti+Nb) microalloying and Ti/Nb are between 0.30～1.0, Ca processing and Ca/S are between 0.8～3.0, control Ti/N waits the metallurgical technology means between 3.0～4.0, optimize TMCP (Thermo-mechanical control process, the mechanical control process of heat) technology, make the acicular ferrite of the microstructure of finished product steel plate for tiny on a small quantity ferrite (10%～20%)+disperse distribution, average grain size is below 15 μ m.
The present inventor combines with special TMCP technology by the unitized design of above-mentioned simple alloying element, obtaining excellent mother metal steel plate low-temperature flexibility, high-tensile, in the time of low yield strength ratio, the low-temperature flexibility of heat affected zone HAZ is excellent too during the large-line energy welding, and successfully solved the conflict mutually in the design of composition design and processes of low-temperature impact toughness and low yield strength ratio, be difficult to the technical barrier of mediation, this not only reduces the consumption of steel, save cost, alleviate the own wt of steel construction, stability and security, what is more important have improved the destructiveness of the security and stability and the antiseismic ripple of steel construction; Improved user's site welding efficient, but the large-line energy weldability has been saved the cost that user's member is made, shortened the time that user's member is made, for the user has created huge value.The microstructure of this type of finished product steel plate is the acicular ferrite that a small amount of tiny ferrite (10%～20%)+disperse distributes, average grain size is below 15 μ m, have the mechanical property of even and excellent, good weldability and lower yield tensile ratio, can apply to high building structure, bridge structure, offshore oil production platform, low-temperature pressure container and large ship structure etc. widely.
This type of steel plate is not only the product of high added value, environmental type, the more important thing is to have formed characteristic senior slab core manufacturing technology.Because the present invention does not need to add any equipment, production technique is simple, and process control is easy, can have the Heavy Plate Production producer that quickens cooling equipment to all and promote, and has very strong adaptability, the feature of environmental protection and high economy.
Description of drawings
The microstructure of Fig. 1 embodiment 3 steel plates, wherein Fig. 1-1 is * 200 times, Fig. 1-2 is * 500 times.
Embodiment
The present invention is further elaborated with embodiment below, but these embodiment have any restriction to the present invention absolutely not.Any change that those skilled in the art are done in to the invention process under the enlightenment of this specification sheets all will drop in the scope of claims.
Embodiment 1
Carry out the continuous casting step by the chemical ingredients shown in the table 1, the steel plate thickness that obtains is 30mm.Carry out the slab low-temperature heat subsequently, Heating temperature is 1080 ℃.Carry out the hot rolling reaction afterwards, in quick continuous rolling step, percentage pass reduction is 15%, and the accumulative total draft is 60%; In the controlled rolling step, percentage pass reduction is 11%, and the accumulative total draft is 67%.Finishing temperature is 793 ℃.After the hot rolling reaction finishes, enter cooling step, the biography time of putting is 28s, and speed of cooling is 15 ℃/s, and stopping cold temperature is 572 ℃.Plate property: see Table 10.
The chemical ingredients of table 1 embodiment 1 steel plate
Embodiment 2
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 2, manufacturing processed is identical with embodiment 1.Steel plate thickness is 70mm.The Heating temperature of slab low-temperature heat is 1110 ℃.In quick continuous rolling step, percentage pass reduction is 12%, and the accumulative total draft is 52%; In the controlled rolling step, percentage pass reduction is 9%, and the accumulative total draft is 60%.Finishing temperature is 765 ℃.The biography time of putting is 46s, and speed of cooling is 11 ℃/s, and stopping cold temperature is 476 ℃.Because the steel plate thickness 〉=40mm of new design steel 2, therefore need slow cooling to 100 ℃ below the back natural air cooling to room temperature.In the present embodiment, the slow cooling end temp is 90 ℃.Plate property: see Table 10.
The chemical ingredients of table 2 embodiment 2 steel plates
Embodiment 3
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 3, manufacturing processed is identical with embodiment 1.Steel plate thickness is 50mm.The Heating temperature of slab low-temperature heat is 1100 ℃.In quick continuous rolling step, percentage pass reduction is 12%, and the accumulative total draft is 55%; In the controlled rolling step, percentage pass reduction is 10%, and the accumulative total draft is 67%.Finishing temperature is 780 ℃.The biography time of putting is 18s, and speed of cooling is 12 ℃/s, and stopping cold temperature is 547 ℃.Because the steel plate thickness 〉=40mm of new design steel 3, therefore need slow cooling to 100 ℃ below the back natural air cooling to room temperature.In the present embodiment, the slow cooling end temp is 95 ℃.Plate property: see Table 10.
The chemical ingredients of table 3 embodiment 3 steel plates
The microstructure of steel plate is seen Fig. 1 shown in the embodiment 3.
Embodiment 4
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 4, manufacturing processed is identical with embodiment 1.Steel plate thickness is 20mm.The Heating temperature of slab low-temperature heat is 1130 ℃.In quick continuous rolling step, percentage pass reduction is 13%, and the accumulative total draft is 70%; In the controlled rolling step, percentage pass reduction is 10%, and the accumulative total draft is 67%.Finishing temperature is 800 ℃.The biography time of putting is 24s, and speed of cooling is 18 ℃/s, and stopping cold temperature is 593 ℃.Plate property: see Table 10.
The chemical ingredients of table 4 embodiment 4 steel plates
Embodiment 5 comparative examples 1---Kawasaki Steel (existing and NKK is merged into JFE)
Carry out the manufacturing (Kawasaki Steel: existing and NKK is merged into JFE) of steel plate by the chemical ingredients shown in the table 5.No manufacturing process data.The steel plate thickness of comparative example 1 is 30mm.Plate property: see Table 10.
The chemical ingredients of table 5 comparative example 1 steel plate
Embodiment 6 comparative example 2---Kawasaki Steels
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 6.No manufacturing process data.The steel plate thickness of comparative example 2 is 75mm.Plate property: see Table 10.
The chemical ingredients of table 6 comparative example 2 steel plates
Embodiment 7 comparative example 3---Kawasaki Steels
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 7.No manufacturing process data.The steel plate thickness of comparative example 3 is 60mm.Plate property: see Table 10.
The chemical ingredients of table 7 comparative example 3 steel plates
Embodiment 8 comparative example 4---Kawasaki Steels
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 8.No manufacturing process data.The steel plate thickness of comparative example 4 is 50mm.Plate property: see Table 10.
The chemical ingredients of table 8 comparative example 4 steel plates
Embodiment 9 comparative example 5---Sumitomo Metal Industries
Carry out the manufacturing of steel plate by the chemical ingredients shown in the table 9.No manufacturing process data.The steel plate thickness of comparative example 5 is 50mm.Plate property: see Table 10.
The chemical ingredients of table 9 comparative example 5 steel plates
The plate property parameter of table 10 embodiment 1-4 steel, comparative example 1-5 steel
Claims (5)
1. but a low yield strength ratio large-line energy welds the high-strength and high-ductility steel plate, it is characterized in that, comprise following component: C:0.025%～0.055%, Si :≤0.20%, Mn:1.40%～1.75%, P :≤0.013%, S :≤0.002%, Cu:0.25%～0.55%, Ni:0.40%～0.80%, Mo:0.10%～0.40%, Nb:0.020%～0.040%, Als:0.040%～0.060%, Ti:0.007%～0.013%, N :≤0.0040%, Ca:0.001%～0.005%, B :≤0.0003%; And above-mentioned constituent content must satisfy following relation simultaneously:
25≤Mn/C≤55,3.0≤Ti/N≤4.0, Ni/Cu 〉=1.5, Ti/Nb is 0.30～1.0, and Ca/S is 0.80～3.0; Surplus is iron and unavoidable impurities,
Described low yield strength ratio is meant the ratio of yield strength/tensile strength, less than 0.85.
2. the preparation method of the described steel plate of claim 1 is characterized in that may further comprise the steps:
1) continuous casting: pouring temperature≤1540 ℃;
2) hot rolling: slab carries out quick continuous rolling in 1070 ℃～1130 ℃ low-temperature heats in the perfect recrystallization district, carries out controlled rolling in the non-recrystallization district,
Described rolling pass draft 〉=12% in the quick continuous rolling in perfect recrystallization district, accumulative total draft 〉=50%,
Described rolling pass draft 〉=8% in the controlled rolling of non-recrystallization district, accumulative total draft 〉=60%, finishing temperature is controlled between 760 ℃～800 ℃;
3) controlled chilling: pass and to put time≤60 second, quicken to be cooled to 450 ℃～600 ℃ with the speed of 〉=10 ℃/s earlier, then slowly cooling and/or natural air cooling to room temperature.
3. preparation method as claimed in claim 2 is characterized in that, described continuous casting step adopts induction stirring or continuously cast bloom gently to depress technology.
4. preparation method as claimed in claim 3 is characterized in that, describedly depresses gently that draft is controlled between 5%～10% in the technology.
5. preparation method as claimed in claim 2 is characterized in that, in the described controlled chilling step, the natural air cooling of back below the steel plate slow cooling to 100 of thickness 〉=40mm ℃ is to room temperature, and steel plate was not less than 24 hours 〉=300 ℃ slow cooling time; The steel plate natural air cooling of thickness＜40mm is to room temperature.
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