CN102337478B - Excellent 100 kg-grade quenched and tempered steel plate with strong toughness and plasticity, and manufacturing method thereof - Google Patents
Excellent 100 kg-grade quenched and tempered steel plate with strong toughness and plasticity, and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses an excellent 100 kg-grade quenched and tempered steel plate with strong toughness and plasticity, and a manufacturing method thereof. The excellent 100 kg-grade quenched and tempered steel plate with strong toughness and plasticity comprises: by weight, 0.09 to 0.15% of C, less than or equal to 0.10% of Si, 0.70 to 1.10% of Mn, less than or equal to 0.013% of P, less than or equal to 0.0030% of S, 0.20 to 0.45% of Cu, 1.30 to 2.00% of Ni, 0.45 to 0.85% of Cr, 0.45 to 0.75% of Mo, 0.045 to 0.070% of Als, 0.008 to 0.025% of Nb, 0.030 to 0.060% of V, 0.004 to 0.010% of Ti, less than or equal to 0.0060% of N, 0.001 to 0.005% of Ca, 0.0006 to 0.0014% of B, and the balance Fe and unavoidable impurities. Through a technology (RQ+RQ+T) combining optimally controlled rolling and offline special conditioning, the excellent 100 kg-grade quenched and tempered steel plate with strong toughness and plasticity forms a microstructure composed of a fine tempered lower bainite and a tempered martensite, wherein an average size of druses is below 20 micrometers; tensile strength is great than or equal to 980MPa; yield strength is great than or equal to 890MPa; and single transverse Charpy impact energy (-60 DEG C) is great than or equal to 47J. Therefore, the excellent 100 kg-grade quenched and tempered steel plate with strong toughness and plasticity has excellent weldability and can solve the problem of over-quenching of a surface of a steel plate with ultra-high strength.
Description
Technical field
The present invention relates to high tensile steel plate and ME thereof; Be particularly related to a kind of obdurability, strong 100 good feather weight hardened and tempered steel plate and method of manufacture thereof of plasticity; This steel plate tensile strength >=980MPa, ys >=890MPa ,-60 ℃ of summers have superior weldability than transverse impact merit (single value) >=47J.
Background technology
As everyone knows; Low-carbon (LC) (HS) low alloy steel is one of most important structural timber, is widely used among petroleum natural gas pipeline, ocean platform, shipbuilding, bridge structure, boiler vessel, building structure, automotive industry, transportation by railroad and the machinofacture; Low-carbon (LC) (HS) low alloy steel performance depends on its chemical ingredients, ME, and wherein intensity, toughness, plasticity and weldableness are the most important performances of low-carbon (LC) (HS) low alloy steel, and its final decision is in the microstructure state of finished steel; Along with metallurgical science and technology constantly advances; People propose higher requirement to the obdurability of high-strength steel, strong plasticity coupling; Promptly when keeping lower manufacturing cost, improve the comprehensive mechanical performance and the use properties of steel plate significantly, practice thrift cost with the consumption that reduces steel; Alleviate own wt, stability and the security of steelwork, what is more important is further to improve steelwork security and stability and cold and hot working property; Started the research climax that develops high-performance steel iron material of new generation in the Japan and Korea S European Union scope at present; Try hard to establish and optimize meter and the innovation manufacturing process technology obtains better microstructure coupling, make high-strength steel obtain better obdurability, strong plasticity coupling through alloy combination.
The high tensile steel plate of existing tensile strength>=980MPa is mainly produced through off-line hardening and tempering process (being RQ+T); But, also can adopt online hardening and tempering process to produce (being DQ+T) for steel plate thickness≤60mm; In order to obtain superstrength, steel plate necessity has sufficiently high hardening capacity, i.e. steel plate hardenability index DI>=3.50 * Finished Steel plate thickness " DI=0.311C
1/2(1+0.64Si) * (1+4.10Mn) * (1+0.27Cu) * (1+0.52Ni) * (1+2.33Cr) * (1+3.14Mo) * 25.4 (mm) "; with guarantee steel plate have sufficiently high intensity, good low-temperature flexibility and along thickness of slab direction microstructure and performance evenly; thereby in steel, add alloying elements such as a large amount of Cr, Mo, Ni, Cu, V inevitably; especially Ni content adds to more than 2.00%; cause the carbon equivalent of steel plate, cold crack Sensitivity Index higher, have a strong impact on the weldableness of steel plate;
Furthermore, the high alloy content steel sheet (sub) over the surface layer hardening is easy to produce, to form coarse martensite, the steel sheet table (near) surface layer of the low-temperature toughness and elongation severe degradation (see "civil power" 1986, Vol.201, P33; "Iron and Steel", 1986, Vol.72, S612; "Iron and Steel", 1986, Vol.72, S614; "Iron and Steel", 1985, Vol.71, S1523; "Iron Hagane ", 1986, Vol.72, S615;" Iron and Steel ", 1986, Vol.73, S1398;" Kawasaki Steel Technical Report ", 1988, Vol.20, P233;" Steel Research ", 1986, Vol.322, P99; CAMP-ISIJ ", 1989, Vol.3, P207;" NKK Technical Report ", 1990, Vol.133, P37;" civil power ", 1994, Vol.249, P1;" Sumitomo Metals " , 1995, Vol.47, P1; "Nishiyama Memorial Technical Seminar" 191-192,2008, P162); low elongation, low temperature toughness is not conducive steel hot and cold workability and fatigue resistance of the plate, anti- sensitivity to stress concentration, crack resistance and structural stability greater impact; hydropower projects in the pressure pipes and casings, thermal power turbine and marine oil platform structure fatigue when used on heavy structure, there is a large safety the hidden dangers; therefore large heavy steel using ultra-high fatigue strength steel, the general hope 100 kg class high strength steel not only has excellent strength and toughness, strength and plasticity matching and weldability, and elongation to ensure more than 14%, in order to ensure steel processing performance and fatigue resistance.
Existing a large amount of patents and TP are just explained intensity and the low-temperature flexibility that how to realize the mother metal steel plate; Just improve steel plate welding ability property; It is less to obtain good welded heat affecting zone HAZ low-temperature flexibility explanation; How not relate to when improving steel plate tensile strength yet, improve the tension unit elongation and the thickness direction mechanical property homogeneity of steel plate, do not point out more how to prevent that steel plate table (Asia) surface layer from crossing quenches.Referring to the clear 63-93845 of Japanese Patent, clear 63-79921, clear 60-258410, special flat 4-285119, special flat 4-308035, flat 3-264614, flat 2-250917, flat 4-143246, U.S. Pat Patent5798004, European patent EP 0288054A2 and " Western Hills souvenir technology lecture " 159-160, the P79～P80 of opening of opening.
Summary of the invention
The purpose of this invention is to provide a kind of obdurability, strong 100 good feather weight hardened and tempered steel plate and method of manufacture thereof of plasticity; Unitized design through the steel plate alloying element combines with special hardening and tempering process (CR+RQT); When obtaining good hardened and tempered steel plate intensity, low-temperature flexibility and obdurability, strong plasticity coupling; The weldableness of steel plate is excellent too; And conflicting and steel plate table (Asia) surface layer that has successfully solved between super-high strength steel plate intensity, plasticity, low-temperature flexibility and the weldableness is crossed the problem of quenching; Be specially adapted to large-scale steel structure and equipment such as hydraulic power pressure water pipe, volute, ocean platform, large-scale engineering machinery, and can realize low-cost stable suitability for industrialized production in batches.
For achieving the above object, technical scheme of the present invention is,
To above-mentioned requirements, the present invention, suitably improves in the steel acid and dissolves Als content and Als>=(Mn equivalent/C) * (N as the basis with the composition system of Mn-(Ti+Nb+V+B) micro-alloyed steel among the low C-
Total-0.292Ti), control (Mn equivalent)/C than between 7～16, Nb/Ti be controlled at 0.8～4.0 between, (Cu+Ni+Mo+Cr) alloying, Ni equivalent>=1.45%, Mo equivalent>=0.32%, Ca handle and Ca/S than between 1.00～3.00, and (Ca) * (S)
0.18≤2.5 * 10
-3, control F * DI index>=metallurgical technology control devices such as 2.50 * Finished Steel plate thickness; Optimal control is rolling+the special hardening and tempering process of off-line (RQ+RQ+T); The microstructure that makes the finished product steel plate is tiny tempering lower bainite+tempered martensite; Average colony size obtains good obdurability/strong plasticity coupling and even along thickness of slab direction mechanical property below 20 μ m, solve ultrahigh-strength steel plates upper layer overquenching problem.
Particularly, obdurability of the present invention, strong 100 good feather weight hardened and tempered steel plates of plasticity, its composition weight percent:
C：0.09％～0.15％
Si：≤0.10％
Mn：0.70％～1.10％
P：≤0.013％
S：≤0.0030％
Cu：0.20％～0.45％
Ni：1.30％～2.00％
Cr：0.45％～0.85％
Mo：0.45％～0.75％
Als：0.045％～0.070％
Nb：0.008％～0.025％
V：0.030％～0.060％
Ti：0.004％～0.010％
N：≤0.0060％
Ca：0.001％～0.005％
B：0.0006％～0.0014％
Surplus is Fe and inevitably is mingled with;
And above-mentioned constituent content must satisfy following relation simultaneously:
Relation between C, the Mn equivalent: 7≤(Mn equivalent)/C≤16, wherein Mn equivalent=Mn+0.56Ni+0.11Cu-0.18Cr-0.81Mo; Guarantee that steel plate is a plastic fracture for fracture behaviour under-60 ℃ of conditions.
Relation between Als, Ti and the N: Als>=(the Mn equivalent/C) * (N
Total-0.292Ti), to separate out with the small and dispersed state to guarantee solid solution in the steel [B]>=5ppm and AlN, austenite grain size before refinement is quenched improves steel plate low-temperature flexibility and even along thickness of slab direction steel plate mechanical property.
Ni equivalent=Ni+0.28Mn+0.13Cu-1.33Si-0.89Al-3.36P>=1.45% to improve ferritic dislocation 1/2<111>(110) low temperature (60 ℃ and following) mobility, is guaranteed the intrinsic toughness of steel plate microstructure.
Mo equivalent=Mo+0.26Cr+1.35V+2.87Nb-0.57Cu-0.12Mn >=0.32% is guaranteed the steel plate anti-temper softening, guarantees ultra thick 100 feather weight hardened and tempered steel plate obdurabilities coupling.
Concern between Nb, the Ti: Nb/Ti is 0.8～4.0, guarantee to form (Ti, Nb) (C, N) tiny evenly disperse is distributed in the steel particle, suppresses in heating, the operation of rolling austenite crystal and grows up, and improves the low-temperature flexibility of steel plate.
Relation between Ca and the S: Ca/S between 1.00～3.00 and (Ca) * (S)
0.18≤2.5 * 10
-3To improve steel plate low-temperature flexibility, weldableness, anti-SR fragility, anti-lamellar tearing performance.
Effective hardenability index D
Eff=F * DI>=2.50 * t guarantees steel plate obdurability coupling and even along thickness of slab direction plate property;
Wherein: F is the boron steel hardening capacity factor, and when having solid solution [B] in the steel and during [B] >=5ppm, F gets 1.2; T is Finished Steel plate thickness (mm);
DI=0.367C
0.5(1+0.7Si) (1+3.33Mn) (1+0.35Cu) (1+0.36Ni) (1+2.16Cr) (1+3Mo) (1+1.75V) (1+1.77Al) * 25.4 (mm) has good obdurability/strong plasticity coupling and even along thickness of slab direction mechanical property to guarantee the ultra thick quenched and tempered steel plate of 80 feather weight.
In composition System Design of the present invention,
For the microstructure that obtains the finished product steel plate is tiny tempering lower bainite+tempered martensite; Average colony size is below 25 μ m; Obtain good obdurability, strong plasticity coupling and along the uniform while of thickness of slab direction mechanical property; Solve ultrahigh-strength steel plates table (Asia) surface layer overquenching problem, steel plate composition design of the present invention has following characteristic with ME:
C, very big to intensity, low-temperature flexibility, unit elongation and the weldableness influence of quenched and tempered steel, from improving extra-thick quenched and tempered steel plate low-temperature flexibility and weldableness angle, hope that C content is controlled lowlyer in the steel; But microstructures Control and manufacturing cost angle from the hardening capacity of quenched and tempered steel, obdurability coupling, manufacturing process, C content should not be controlled lowly excessively, especially superstrength 100 feather weight hardened and tempered steel plates; Dimension C content zone of reasonableness is 0.09%～0.15%.
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 hardened and tempered steel plate colony, increase between the lath the position to 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; But segregation takes place in Mn easily in the molten steel solidification process; When especially Mn content is higher, not only can cause pouring operation difficulty, and easily and element generation conjugation segregation phenomenas such as C, P, S, Mo, Cr; When especially C content is higher in the steel; The segregation that increases the weight of the strand centre is with loose, and serious strand central zone is segregated in follow-up rolling, thermal treatment and the welding process and is prone to form abnormal structure, causes the low and welding joint of hardened and tempered steel plate low-temperature flexibility crackle to occur; Therefore according to the C content range, select suitable Mn content range extremely necessary for the superstrength hardened and tempered steel plate, composition of steel system and C content are 0.09%～0.15% according to the present invention; Being fit to Mn content is 0.70%～1.10%; And when C content was high, Mn content suitably reduced, and vice versa; And when C content hanged down, Mn content suitably improved.
Si promotes deoxidation of molten steel and can improve armor plate strength, but adopts the molten steel of Al deoxidation; The desoxydatoin of Si is little, though Si can improve the intensity of steel plate, and low-temperature flexibility, unit elongation and the weldableness of Si heavy damage steel plate (especially high-strength hardened and tempered steel plate); Especially under than the large-line energy welding conditions; Si not only promotes the M-A island to form, and comparatively thick, the skewness of M-A island size that forms, heavy damage welded heat affecting zone (HAZ) toughness and welding joint SR performance; Therefore the Si content in the steel should be controlled lowly as far as possible; The present invention is controlled to be ultralow Si, considers the economy and the operability of steelmaking process, and Si content is controlled at below 0.10%.
P is mingled with the mechanical property to steel plate as harmful in the steel, and especially low-temperature impact toughness, unit elongation, weldableness and welding joint SR performance have huge detrimental effect, and it is low more good more to require in theory; But consider steel-making operability and steel-making cost, for the superstrength hardened and tempered steel plate that requires superior weldability ,-60 ℃ of toughness and excellent strength-toughness and strong plasticity to mate, 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 plate 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 low-temperature impact toughness of heavy damage steel plate, unit elongation, Z are to performance, weldableness and welding joint SR performance, and S produces hot short principal element in the course of hot rolling simultaneously, and it is low more good more to require in theory; But consider steel-making operability, steel-making cost and the smooth and easy principle of logistics, for the superstrength hardened and tempered steel plate that requires superior weldability ,-60 ℃ of toughness and excellent strength-toughness and strong plasticity to mate, S content need be controlled at≤and 0.0030%.
Cr; As weak carbide forming element; Add hardening capacity, promotion martensite/bainite formation that Cr not only improves steel plate, and the position increases to difference between martensite/lath of bainite, the increase crackle passes the resistance of martensite/bainite colony; When improving armor plate strength, the have some improvement effect of steel plate toughness of tool; But when the Cr addition is too much, the weldableness of heavy damage steel plate, especially welding joint SR performance; But for superstrength 100 feather weight hardened and tempered steel plates, certain Cr content must be arranged, have enough hardening capacity to guarantee steel plate; Therefore Cr content is controlled between 0.45%～0.85%.
Mo; Add the hardening capacity of Mo raising steel plate, promote martensite/bainite to form, but Mo is as the strong carbide forming element; When promoting that martensite/bainite forms; The position is very little to difference between the increase martensite/size of bainite colony and the martensite/lath of bainite of formation, reduces the resistance that crackle passes martensite/bainite colony, and Mo promotion superstrength quenched and tempered steel table (Asia) surface layer is crossed and quenched in addition; Therefore Mo has reduced low-temperature flexibility, the unit elongation of hardened and tempered steel plate when increasing substantially hardened and tempered steel plate intensity, brings out steel plate table (Asia) surface layer and crosses and quench; And when Mo adds when too much, the not only unit elongation of heavy damage steel plate, weldableness and welding joint SR performance, and increase steel plate SR fragility and production cost; But for superstrength 100 feather weight hardened and tempered steel plates, certain Mo content must be arranged, have enough hardening capacity and anti-temper softening to guarantee steel plate.Therefore the phase transformation strengthening effect of taking all factors into consideration Mo reaches the influence to mother metal steel plate low-temperature flexibility, unit elongation and weldableness, and Mo content is controlled between 0.45%～0.75%.
Ni adds Ni and not only can improve dislocation mobility in the ferritic phase, promotes dislocation to hand over slippage, and increases between martensite/lath of bainite the position to poor; Ni reduces Ar as austenite stabilizer element
3The point temperature, refinement martensite/bainite colony size, so Ni has the function that improves hardened and tempered steel plate intensity, unit elongation and low-temperature flexibility simultaneously; Add the copper brittleness phenomenon that Ni can also reduce Copper Bearing Steel in the steel, alleviate the intergranular cracking of course of hot rolling, 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, and the welded heat affecting zone but too high Ni content can harden is unfavorable to the weldableness and the welding joint SR performance of steel plate; But for superstrength 100 feather weight hardened and tempered steel plates, enough Ni content must be arranged, have enough hardening capacity, uniform while of thickness of slab directional performance, guarantee the low-temperature flexibility of steel plate to guarantee steel plate; Therefore, Ni content is controlled between 1.30%～2.00%, with the obdurability level of the hardening capacity of guaranteeing steel plate and steel plate and do not damage the weldableness of steel plate.
Cu also is an austenite stabilizer element, adds 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 0.45%, causes copper brittleness, casting billet surface be full of cracks, implosion problem to reach especially ultrahigh-strength steel plates welding joint SR performance degradation easily; For 100 feather weight superstrength hardened and tempered steel plates, the Cu addition is very few, is lower than 0.20%, and institute cuts any ice very little; Therefore Cu content is controlled between 0.20%～0.45%; Cu, the compound interpolation of 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, Cu, the compound interpolation of Ni can reduce Ar significantly
3, improve the motivating force of austenite to ferrite transformation, cause martensite/lath of bainite can be to each position to growing up, cause that the position becomes big to difference between martensite/lath of bainite, increase the resistance that crackle passes martensite/lath of bainite.
B, content are controlled between 0.0006%～0.0014%, when guaranteeing steel plate hardening capacity, do not damage weldableness, HAZ toughness and the steel slab surface quality of steel plate.
Ti, content are between 0.004%～0.010%, and austenite crystal is too grown up in the heating of inhibition slab, the course of hot rolling, improves the steel plate low-temperature flexibility, the more important thing is and suppresses HAZ grain growth in the welding process, improves HAZ toughness; In addition, Ti has solid N effect, eliminates free N in the steel, guarantees that the B element exists with solid solution B form; Yet when Ti content surpassed 0.010%, under high acid-soluble aluminum content condition, superfluous Ti was separating out with TiC on martensite/lath of bainite and on colony circle, serious embrittlement steel plate microstructure.
The Nb element purpose of adding trace in the steel is to carry out non-recrystallization controlled rolling, refinement steel plate microstructure; Improve steel plate table (Asia) surface layer quenching structure; Prevent steel plate table (Asia) surface layer overquenching; Improve the coupling between superstrength hardened and tempered steel plate intensity, toughness and the plasticity, when the Nb addition is lower than 0.008%, remove the controlled rolling effect that effectively to bring into play; When the Nb addition surpasses 0.025%; Bringing out upper bainite (Bu) under the large-line energy welding conditions forms and Nb (C; N) secondary is separated out embrittling effect; The low-temperature flexibility of heavy damage large-line energy welded heat affecting zone (HAZ); Therefore Nb content is controlled between 0.008%～0.025%, when obtaining best controlled rolling effect, realization superstrength hardened and tempered steel plate obdurability/strong plasticity coupling and preventing table (Asia) surface layer overquenching, does not damage the toughness of large-line energy welding and multi-pass welded H AZ again.
Als in the steel is the freedom [N] in the steel fixedly, removes and reduces welded heat affecting zone (HAZ) free [N], improves outside the low-temperature flexibility effect of welded H AZ, the more important thing is to guarantee to have certain solid solution B in the steel, improve steel plate hardening capacity; Therefore the Als lower limit is controlled at 0.045%; 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 weldableness, so the Als upper limit is controlled at 0.070%.
In order to ensure the existence of solid solution in the steel plate [B] and prevent that a large amount of thick AlN from separating out along original austenite crystal prevention, the impelling strength of infringement steel plate is low-temperature impact toughness especially laterally, and the N content in the steel must not surpass 0.006%.
V content is between 0.030%～0.060%, and along with the increase of steel plate thickness, V content is the capping value suitably.Adding the V purpose is that (C N) separates out in the bainite/martensite lath, improves the intensity of hardened and tempered steel plate through V.V adds very few, is lower than 0.030%, and (C N) very little, can not effectively improve the intensity of superstrength hardened and tempered steel plate to the V that separates out; The V addition is too much, is higher than 0.060%, infringement steel plate low-temperature flexibility, unit elongation, weldableness and welding SR performance.
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 S red brittleness, improve steel plate low-temperature flexibility, unit elongation and Z to performance, improve steel plate flexible anisotropy and weldableness, adopt Ca to handle in addition, improve the cast that peracid dissolves aluminum steel water; 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 weldableness of low-temperature flexibility, unit elongation and the steel plate 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%～0.0040%.
In addition, the method for manufacture of obdurability of the present invention, 100 feather weight hardened and tempered steel plates that strong plasticity is good, it comprises the steps:
1) smelts, casts
Pressing mentioned component smelts; Adopt continuous casting or die casting to be cast into base, continuous casting basket pouring superheating temperature Δ T is controlled at 10 ℃～30 ℃, and pulling rate is controlled at 0.6m/min～1.0m/min; Liquid level fluctuation of crystallizer is controlled at≤5mm, prevents that the continuously cast bloom surface from producing defectives such as slag inclusion, pore; Die casting cast superheating temperature Δ T is controlled at 50 ℃～70 ℃;
2) rolling, steel plate overall compression ratio (slab thickness/Finished Steel plate thickness) >=3.5 guarantees that superstrength hardened and tempered steel plate microstructure is evenly tiny, and especially steel plate table (Asia) surface layer has certain strain storage rate;
Fs is common rolling, for guaranteeing that [Al]+BN → AlN+ [B] takes place in the heating and the operation of rolling, guarantees solid solution in the steel [B]>=5ppm, and slab heating temperature is controlled between 1100 ℃～1200 ℃; It is rolling to have at least 2 passages to adopt low speed to depress greatly, and the steel plate rolling speed control is in≤1.2m/sec., the rolled form factor (Δ H/R)
1/2>=0.18, wherein Δ H is a reduction in pass, and the mm of unit, R are working roll roller footpath, and the mm of unit is evenly tiny to guarantee the steel plate microstructure;
Subordinate phase adopts controlled rolling, controlled rolling start rolling temperature≤900 ℃, rolling pass draft>=8%; Crystallizing field (≤900 ℃) does not add up draft>=50%; 750 ℃～850 ℃ of finishing temperatures, the refine austenite grain-size is improved superstrength hardened and tempered steel plate obdurability coupling;
3) steel plate is from stopping the cold junction bundle to going into to be not more than pitch time the burial pit insulation 60min, heat preservation method be the steel billet temperature surface greater than being incubated 36 hours at least under 300 ℃ the condition, guarantee that the ultra-thick steel plates dehydrogenation is abundant, prevent to produce hydrogen induced cracking;
4) thermal treatment process adopts secondary quenching+tempering process, and with refinement surface of steel plate layer crystal particle size, inhibition steel plate top layer is crossed and quenched;
Steel plate quenching temperature (plate temperature) is 900～930 ℃ for the first time, the hold-time >=15～45min that quenches, the soaking time that the hold-time of quenching picks up counting when reaching the quenching target temperature for the steel plate core temperature;
Steel plate quenching temperature (plate temperature) is 870～890 ℃ for the second time, the hold-time >=10～40min that quenches, the soaking time that the hold-time of quenching picks up counting when reaching the quenching target temperature for the steel plate core temperature;
Steel plate tempering temperature (plate temperature) is 610～650 ℃; Tempering temperature was limit on the upper side when steel plate was relatively thin, tempering temperature was limit on the lower side when steel plate was thicker relatively; The tempering hold-time (min) >=(0.65～1.0) * Finished Steel plate thickness (mm); The soaking time that the tempering hold-time picks up counting when reaching the tempering target temperature for the steel plate core temperature, unit time is min; Tempering finishes back steel plate natural air cooling to room temperature.
The present invention adopts secondary quenching, and steel plate quenching homogenizing steel plate tissue prevents that further the quenching for the first time of steel plate table (Asia) surface layer tissue from taking place to quench, and influences steel plate table (Asia) layer low-temperature flexibility and plasticity for the first time; Steel plate quenching makes steel plate full thickness homogeneous microstructure tiny for the second time, guarantees ultrahigh-strength steel plates obdurability, strong plasticity coupling.
The composition system of steel and armor plate strength, plasticity and low-temperature flexibility requirement according to the present invention; The design and manufacture technology scheme is: adopt the continuous casting casting; Basket pouring superheating temperature Δ T is controlled at 10 ℃～30 ℃, and pulling rate is controlled at 0.6m/min～1.0m/min, and liquid level fluctuation of crystallizer is controlled at≤5mm.
Beneficial effect of the present invention
When obtaining good 100 feather weight superstrength hardened and tempered steel plate obdurabilities, strong plasticity coupling; The weldprocedure property of steel plate is excellent too; And successfully solved conflicting between super-high strength steel plate intensity, plasticity, low-temperature flexibility and the weldableness, improved security and stability, the anti-fatigue performance of large-scale heavy steelwork; Good weldableness has been saved the cost that user's steel member is made, and has shortened the time that user's steel member is made, and for the user has created huge value, thereby this type of steel plate is not only the product of high added value, green environmental protection.
Description of drawings
Fig. 1 is the photo of the microstructure (1/4 thickness) of the embodiment of the invention 2 steel.
Embodiment
Below in conjunction with embodiment the present invention is done further.
Table 1 is composition embodiment of the present invention, and table 2～table 4 is the ME of embodiment, and table 5 is the plate property of embodiment.
As can beappreciated from fig. 1, the microstructure tempered martensite of steel of the present invention and tempering lower bainite size are tiny, even, thereby have guaranteed that 100 feather weight hardened and tempered steel plates have good strong plasticity, obdurability coupling.
The present invention combines with special hardening and tempering process (CR+QQT) through the unitized design of steel plate alloying element; When obtaining good superstrength hardened and tempered steel plate intensity, low-temperature flexibility and obdurability coupling; The weldableness of steel plate is excellent too; And conflicting and steel plate table (Asia) surface layer that has successfully solved between super-high strength steel plate intensity, plasticity, low-temperature flexibility and the weldableness crosses the problem of quenching, and improved security and stability, the anti-fatigue performance of steelwork; Good weldableness has been saved the cost that user's steel member is made, and has shortened the time that user's steel member is made, and for the user has created huge value, thereby this type of steel plate is not only the product of high added value, green environmental protection.
The present invention's 100 feather weight H.T. hardened and tempered steel plates as flow pipe, volute, large-scale engineering machinery structure and the offshore platform of making hydroelectric project, are the critical materials of the great development of the national economy mainly.Domestic each big steel mill (except that Baosteel) all can not produce at present; Required 100 feather weight H.T. hardened and tempered steel plates such as domestic large-scale Heavy Machinery Plant, hydroelectric project, oceanographic engineering are all from Japan and German import; Not only steel plate import price and supplementary technology service fee are expensive; And can't guarantee delivery date; Force the user before design paper comes out, order in advance and have certain size surplus steel plate, so that after design paper comes out; The plate size that requires according to design paper requires the cutting steel plate, causes the huge waste of material.
Along with the Chinese national economy development; Build the requirement of saving type harmonious society; National basis engineering construction, energy project construction (like hydroelectric project), ocean exploitation construction and build required Large-Scale Equipment manufacturing development and put day thing agenda, as strategic base mateiral---100 feather weight H.T. hardened and tempered steel plates have vast market prospect; 100 feather weight H.T. hardened and tempered steel plates also belong to a kind of brand-new steel grade for China, and except that Baosteel, domestic other iron and steel enterprise never studies and produced.Present 100 feather weight H.T. hardened and tempered steel plates produce line and successfully manufacture experimently, and steel plate comprehensive mechanical property in kind and excellent weldability possess the volume shipment condition.
Claims (2)
1. obdurability, strong 100 good feather weight hardened and tempered steel plates of plasticity, its composition weight percent is:
C：0.09%～0.15%
Si：≤0.10%
Mn：0.70%～1.10%
P：≤0.013%
S：≤0.0030%
Cu：0.20%～0.45%
Ni：1.30%～2.00%
Cr：0.45%～0.85%
Mo：0.45%～0.75%
Als：0.045%～0.070%
Nb：0.008%～0.025%
V：0.030%～0.060%
Ti：0.004%～0.010%
N：≤0.0060%
Ca：0.001%～0.005%
B：0.0006%～0.0014%
Surplus is Fe and inevitably is mingled with;
And mentioned component content must satisfy following relation simultaneously:
Relation between C, the Mn equivalent: 7≤(Mn equivalent)/C≤16, wherein Mn equivalent=Mn+0.56Ni+0.11Cu-0.18Cr-0.81Mo;
Relation between Als, Ti and the N: Als>=(the Mn equivalent/C) * (N
Total-0.292Ti), separate out austenite grain size before refinement is quenched with the small and dispersed state to guarantee solid solution in the steel [B]>=5ppm and AlN;
Ni equivalent=Ni+0.28Mn+0.13Cu-1.33Si-0.89Als-3.36P >=1.45%;
Mo equivalent=Mo+0.26Cr+1.35V+2.87Nb-0.57Cu-0.12Mn >=0.32%;
Concern between Nb, the Ti: Nb/Ti is 0.8～4.0;
Concern between Ca and the S: Ca/S is between 1.00～3.00, (Ca) * (S)
0.18≤2.5 * 10
-3
Effective hardenability index D
Eff=F * DI>=2.50 * t
Wherein, F is the boron steel hardening capacity factor, and when having solid solution [B] in the steel and during [B] >=5ppm, F gets 1.2; T is the Finished Steel plate thickness, the mm of unit;
DI=0.367C
0.5(1+0.7Si)(1+3.33Mn)(1+0.35Cu)(1+0.36Ni)(1+2.16Cr)(1+3Mo)(1+1.75V)(1+1.77Als)×25.4mm。
2. the method for manufacture of obdurability as claimed in claim 1,100 feather weight hardened and tempered steel plates that strong plasticity is good, it comprises the steps:
1) smelts, casts
Smelt by aforesaid right requirement 1 composition, adopt continuous casting or die casting to be cast into base, continuous casting basket pouring superheating temperature Δ T is controlled at 10 ℃～30 ℃, and pulling rate is controlled at 0.6m/min～1.0m/min, and liquid level fluctuation of crystallizer is controlled at≤5mm; Die casting cast superheating temperature Δ T is controlled at 50 ℃～70 ℃;
2) rolling, the steel plate overall compression ratio is slab thickness/Finished Steel plate thickness >=3.5;
Fs is common rolling, for guaranteeing that [Al]+BN → AlN+ [B] takes place in the heating and the operation of rolling, guarantees solid solution in the steel [B]>=5ppm, and slab heating temperature is controlled between 1100 ℃～1200 ℃; It is rolling to have at least 2 passages to adopt low speed to depress greatly, and the steel plate rolling speed control is in≤1.2m/sec., the rolled form factor (Δ H/R)
1/2>=0.18, wherein Δ H is a reduction in pass, and the mm of unit, R are working roll roller footpath, and the mm of unit is evenly tiny to guarantee the steel plate microstructure;
Subordinate phase adopts controlled rolling, controlled rolling start rolling temperature≤900 ℃, rolling pass draft>=8%, i.e.≤900 ℃ of accumulative total draft>=50% of crystallizing field, 750 ℃～850 ℃ of finishing temperatures;
3) steel plate is from stopping the cold junction bundle to going into to be not more than pitch time the burial pit insulation 60min, heat preservation method be the steel billet temperature surface greater than being incubated 36 hours at least under 300 ℃ the condition, guarantee that the ultra-thick steel plates dehydrogenation is abundant, prevent to produce hydrogen induced cracking;
4) thermal treatment process adopts secondary quenching+tempering process
The steel plate quenching temperature is 900～930 ℃ for the first time, the hold-time 15～45min that quenches, the soaking time that the hold-time of quenching picks up counting when reaching the quenching target temperature for the steel plate core temperature;
The steel plate quenching temperature is 870～890 ℃ for the second time, the hold-time 10～40min that quenches, the soaking time that the hold-time of quenching picks up counting when reaching the quenching target temperature for the steel plate core temperature;
The steel plate tempering temperature is 610～650 ℃; Tempering temperature was limit on the upper side when steel plate was relatively thin, tempering temperature was limit on the lower side when steel plate was thicker relatively; The tempering hold-time: (0.65～1.0) * Finished Steel plate thickness; Thickness unit: mm, the soaking time that the tempering hold-time picks up counting when reaching the tempering target temperature for the steel plate core temperature, unit time is min; Tempering finishes back steel plate natural air cooling to room temperature.
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