CN102618799B - High-performance quenched and tempered steel plate with 80 kg carbon equivalent and manufacturing method of high-performance quenched and tempered steel plate - Google Patents

Abstract

The invention provides a high-performance quenched and tempered steel plate with 80 kg carbon equivalent and a manufacturing method of the high-performance quenched and tempered steel plate. The high-performance quenched and tempered steel plate comprises the following ingredients by weight percent: 0.05 to 0.12 percent of C, 0 to 0.20 percent of Si, 1.20 to 1.60 percent of Mn, 0 to 0.013 percent of P, 0 to 0.003 percent of S, 0.10 to 0.30 percent of Cu, 0.10 to 0.40 percent of Ni, 0.10 to 0.30 percent of Cr, 0.05 to 0.30 percent of Mo, 0.035 to 0.065 percent of Als, 0.005 to 0.011 percent of Ti, 0.015 to 0.045 percent of V, 0 to 0.0060 percent of N, 0.001 to 0.004 percent of Ca, 0.0006 to 0.0013 percent of B, and Fe in balancing amount. By adopting a low-C low-Si high-Mn low-N-(Ti+N+B) microalloyed steel ingredient system as the foundation, and optimizing recrystallization rolling control, quenching and tempering process, the invention has the advantages that the microstructure of the steel plate is tiny tempered martensite or tempered lower bainite; the average size of colonies is lower than 25 Mum; the yield strength is larger than or equal to 690MPa; the tensile strength is larger than or equal to 780 MPa; the Charpy impact power (single value) at -40 DEG C is equal to or larger than 100 J; moreover, the Charpy impact power (single value) of a welding heat affected zone (HAZ) at -40 DEG C is equal to or larger than 47 J, and the stretch rate Delta 5 thereof is equal to or larger than 15 percent.

Description

Low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plate and manufacture method thereof

Technical field

The present invention relates to the manufacture method of hardened and tempered steel plate, being particularly related to low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plates and manufacture method thereof arrives, hardened and tempered steel plate yield strength>=690MPa, tensile strength>=780MPa, the Charpy ballistic work of-40 ℃ (single value)>=100J, superior weldability is Charpy ballistic work (single the value)>=47J of-40 ℃ of welded heat affecting zone (HAZ), extensibility δ ₅>=15%, the microstructure of hardened and tempered steel plate is tiny tempered martensite+tempering lower bainite.

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, boiler vessel, building structure, automotive industry, transportation by railroad and machinofacture.Low-carbon (LC) (high strength) low alloy steel performance depends on the process system of its chemical composition, manufacturing processed, 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 chemical composition and the microstructure of finished steel.Along with science and technology constantly advances, people propose higher requirement to the obdurability of high-strength steel, strong plasticity coupling, when maintaining lower manufacturing cost, improve significantly comprehensive mechanical performance and the use properties of steel plate, consumption with minimizing steel is cost-saving, alleviate own wt, stability and the security of steel construction, what is more important is further to improve steel construction security and stability and cold and hot working.

Within the scope of Japan and Korea S European Union, started the research climax that develops high-performance steel iron material of new generation at present, try hard to establish to optimize meter and reform manufacturing process technology by alloy combination obtain better Organization Matching, when making high-strength steel obtain better obdurability, strong plasticity coupling and weldability, realize stable batch, low cost fabrication, improve product competitiveness in the market.

The hardened and tempered steel plate that traditional tensile strength is greater than 780MPa mainly adds tempering (DQT or QT) by quenching, be that so-called hardening and tempering method is produced, this just requires steel plate necessity to have sufficiently high hardening capacity, i.e. hardenability index DI>=2 * finished steel plate thickness " 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) ", to guarantee that steel plate has sufficiently high intensity, good low-temperature flexibility and along the microstructure of steel plate thickness direction and performance evenly, therefore inevitably in steel, add a large amount of Cr, Mo, Ni, the alloying elements such as Cu, Mo in this class steel plate, the alloying element contents such as Ni generally will be controlled at>=and 0.50%, carbon equivalent Ceq is also up to more than 0.50%, will be controlled at>=more than 1.00% (clear 59-129724 of noble element Ni content even, flat 1-219121).So, not only the alloy content of steel plate is higher, and carbon equivalent Ceq and welding cold cracking Sensitivity Index Pcm are also higher, and this brings larger difficulty to site welding, before weldering, need preheating, postwelding to need thermal treatment, welding cost raises, welding efficiency reduces, welding scene Working environment worsens; And the also significantly rising of steel plate manufacturing cost, affect the steel plate market competitiveness and promote the use of.Although this hardening and tempering process is produced the requirement that the technical indicators such as intensity, low-temperature flexibility and unit elongation of steel plate can meet user, but steel plate manufacturing cost is high, welding processing cost of manufacture is high, except the engineerings such as the pressure water pipe of high request and volute, low-temperature high-strength container, ocean platform are used, be difficult to promote to industries such as the engineering machinery having a large capacity and a wide range, bridge structure, automotive industry and transportation by railroads, the use range of product is subject to larger restriction.

Existing a large amount of patent documentation just illustrates intensity and the low-temperature flexibility that how to realize mother metal steel plate, just improve Plate Welding energy, obtain the HAZ low-temperature flexibility explanation of good welded heat affecting zone less, do not relate to how when improving steel plate tensile strength yet, improve the tension unit elongation of steel plate, more do not relate to and stably reduce how in batches manufacturing cost and the welding processing cost of manufacture of steel plate, referring to the clear 63-93845 of Japanese Patent, clear 63-79921, clear 60-258410, Te Pingkai 4-285119, Te Pingkai 4-308035, flat 3-264614, flat 2-250917, flat 4-143246 and US Patent No. Patent4855106, US Patent5183198, US Patent4137104, US Patent4790885, US Patent4988393, US Patent5798004, European patent EP 0867520A2, EP 0288054A2 etc.

Summary of the invention

The object of this invention is to provide a kind of low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plate and manufacture method thereof, unitized design by steel plate alloying element combines with special hardening and tempering process (RCR+QT), is obtaining excellent low-temperature flexibility, high strength (tensile strength>=780MPa), unit elongation δ ₅in the time of>=15%, steel plate has ultralow carbon equivalent Ceq, and good weldability be the more important thing is and realized quenching and tempering, high plate low cost fabrication, low welding processing cost of manufacture; And the over-all properties that has successfully solved high-strength hardened and tempered steel plate is conflicted in Composition Design, technological design mutually with manufacturing cost, welding processing cost of manufacture, the very difficult problem being in harmonious proportion, when improving quenching and tempering, high plate over-all properties, will cause the rising of manufacturing cost, welding processing cost; Otherwise, when reducing quenching and tempering, high plate manufacturing cost, welding processing cost, will cause the sharply decline of steel plate over-all properties; When how to obtain quenching and tempering, high plate Good All-around Property, user's use properties, mother metal steel plate has cheap manufacturing cost simultaneously.

For achieving the above object, technical scheme of the present invention is:

The present invention adopts the composition system of the low N-of the high Mn-of the low Si-of low C-(Ti+V+B) micro-alloyed steel as basis, suitably improves sour molten Als content and Als>=12 * [(%N in steel _total)-0.292 (%Ti)], control Mn/C>=12, Ceq≤0.43%, (%Si) * (%C)≤0.012, Mo equivalent>=0.30%, Cr equivalent>=0.40%, Ni/Cu>=0.50, (Cu+Ni+Mo+Cr) alloying, Ca and process, and Ca/S compares between 1.00～3.00, (%Ca) * (%S) ^0.18≤ 2.5 * 10 ^-3, control the metallurgical technology control devices such as F * DI index>=1.2 * finished steel plate thickness, optimize recrystallize controlled rolling+hardening and tempering process (Q+T), the microstructure that makes finished steel plate is tiny tempered martensite+tempering lower bainite, average colony size, below 25 μ m, obtains evenly good obdurability.

Concrete, low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plates of the present invention, its composition weight percent is: C:0.05%～0.12%, Si :≤0.20%, Mn:1.20%～1.60%, P :≤0.013%, S :≤0.003%, Cu:0.10%～0.30%, Ni:0.10%～0.40%, Cr:0.10%～0.30%, Mo:0.05%～0.30%, Als:0.035%～0.065%, Ti:0.005%～0.011%, V:0.015%～0.045%, N :≤0.0060%, Ca:0.001%～0.004%, B:0.0006%～0.0013%, all the other are Fe and inevitable impurity, and above-mentioned constituent content must meet following relation simultaneously:

Mn/C >=12, guarantee steel plate Charpy bar fracture fibre ratio >=50% under-40 ℃ of conditions;

Als>=12 * [(%N _total)-0.292 (%Ti)], to guarantee thering is enough solid solution Als in steel, prevent that N is combined with B, form BN, solid solution [B] in protection steel, and suppress AlN and separate out at the thick chain of original austenite crystal prevention, promote that AlN separates out at intracrystalline and crystal boundary with small and dispersed state, improve steel plate low-temperature flexibility, weldability;

Control Ceq≤0.43%, improve the weldability of high-strength quenched and tempered steel, guarantee that steel plate is not welding under preheating condition;

(%Si) * (%C)≤0.012, increases martensitic transformation critical cooling velocity, promotes lower bainite to form, and improves high-strength hardened and tempered steel plate obdurability coupling; Suppress welded H AZZhong M/A island and separate out, improve Plate Welding and welded H AZ toughness;

Mo equivalent >=0.30%, Cr equivalent >=0.40%, guarantee hardened and tempered steel plate hardening capacity and anti-temper softening, guarantees that 80 feather weight hardened and tempered steel plate obdurabilities of Ultra-low carbon equivalent mate with strong plasticity; Mo equivalent=Mo+0.67Cr+0.83Si+1.62V wherein; Cr equivalent=Cr+1.21Mo+Si+1.86V.

Ni/Cu >=0.50, prevents that Cu is crisp, when improving mother metal steel plate low-temperature impact toughness, and the Reheat embrittlement while preventing from welding.

Ca/S is between 1.00～3.00, and (%Ca) * (%S) ^0.18≤ 2.5 * 10 ^-3; To improve steel plate low-temperature flexibility, weldability, anti-SR fragility, anti-lamellar tearing performance.

Control F * DI index>=1.2 * t, guarantee the unit elongation after 80 feather weight ultrahigh-strength steel plates obdurability couplings, low-temperature flexibility and tempering; Wherein F is B element hardening capacity contribution factor; While there is solid solution [B] in steel, F gets 1.2; T is finished steel plate thickness (mm); DI=0.367 (%C) ^0.5[1+0.7 (%Si)] [(1+3.33 (%Mn)] [(1+0.35 (%Cu)] [(1+0.36 (%Ni)] [(1+2.16 (%Cr)] [(1+3 (%Mo)] [(1+1.75 (%V)] [(1+1.77 (%Al)] * 25.4 (mm).

In the Composition Design of steel of the present invention:

C is very large on the intensity of quenched and tempered steel, low-temperature flexibility, unit elongation and weldability impact, from improving low-temperature flexibility, unit elongation and the weldability angle of quenched and tempered steel, wishes that in steel, C content is controlled lowlyer; But microstructures Control and manufacturing cost angle from the intensity of quenched and tempered steel, manufacturing process, C content should not be controlled too lowly; When C content is higher, although be conducive to improve quenched and tempered steel intensity, damage low-temperature flexibility, unit elongation and the weldability of quenched and tempered steel, so C content is unsuitable too high.The above analysis C content range is controlled at 0.05～0.12%.

Mn as most important alloying element in steel except improving the intensity of quenched and tempered steel, also there is the austenite of expansion phase region, reduce Ar ₃point temperature, refinement quenched and tempered steel colony and improve steel plate low-temperature flexibility effect, promote low temperature phase change tissue to form and the effect of raising quenched and tempered steel intensity; But easily there is segregation in Mn in molten steel solidification process, when especially Mn content is higher, not only can cause pouring operation difficulty, and easily and the element generation conjugation segregation phenomena such as C, P, S; When especially C content is higher in steel, increase the weight of the segregation in strand centre with loose, serious strand central zone is segregated in follow-up rolling and welding process and easily forms abnormal structure, causes hardened and tempered steel plate low-temperature flexibility and unit elongation low; Therefore according to C content range, select suitable Mn content range extremely necessary for high-strength hardened and tempered steel, according to the present invention, composition of steel system and C content are 0.05～0.12%, being applicable to Mn content is 1.20%～1.60%, and when C content is high, Mn content suitably reduces, and vice versa; And when C content is low, Mn content suitably improves.

Si promotes deoxidation of molten steel and can improve quenched and tempered steel intensity, but adopt the molten steel of Al deoxidation, the desoxydatoin of Si is little, although Si can improve the intensity of steel plate, but Si suppresses lower bainite to be formed, the low-temperature flexibility of grievous injury steel plate, unit elongation and weldability, especially under compared with Large Heat Input Welding condition, Si not only promotes M-A island to form, and it is comparatively thick to form M-A island size, skewness, the toughness of grievous injury welded heat affecting zone (HAZ), therefore the Si content in steel should be controlled lowly as far as possible, consider steel-making cost, Si content is controlled at below 0.20%.

P is the mechanical property to quenched and tempered steel as detrimental impurity in steel, and especially low-temperature impact toughness, unit elongation and weldability have huge detrimental effect, and it is more low better to require in theory; But consider steel-making operability, steel-making cost and the smooth and easy principle of logistics, P content need to be controlled at≤and 0.013%.

S has very large detrimental effect as detrimental impurity in steel to the low-temperature flexibility of quenched and tempered steel, the more important thing is that S is combined with Mn in steel, form MnS inclusion, in course of hot rolling, the plasticity-of MnS makes MnS along rolling to extension, forms along rolling to MnS inclusion band the low-temperature impact toughness of grievous injury steel plate, unit elongation, Z-direction performance and weldability, in S or course of hot rolling, produce hot short principal element, it is more low better to require in theory simultaneously; But consider steel-making operability, steel-making cost and the smooth and easy principle of logistics, S content need to be controlled at≤and 0.003%.

Cu is also austenite stabilizer element, adds Cu and also can reduce Ar ₃point temperature, improves the hardening capacity of steel plate and the resistance to atmospheric corrosion of steel plate; But Cu addition is (higher than 0.30%) too much, not only cause hardened and tempered steel plate carbon equivalent to raise, the more important thing is and easily cause copper brittleness, casting billet surface be full of cracks, implosion problem and super-thick steel plate welding joint SR performance degradation especially; Cu addition is very few, and lower than 0.10%, institute cuts any ice very little; Therefore Cu content is controlled between 0.10%～0.30%; The compound interpolation of Cu, Ni except reduce Copper Bearing Steel copper brittleness phenomenon, 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 significantly reduce Ar ₃, improve austenite to the motivating force of ferrite transformation, cause martensite/lath of bainite to cause position between martensite/lath of bainite to become large to poor to each position to growing up, increase crackle through the resistance of martensite/lath of bainite.

Add Ni and not only can promote ferritic phase Dislocations to hand over slippage, improve dislocation mobility, and increase between martensite/lath of bainite position to poor; Ni, as austenite stabilizer element, reduces Ar ₃point temperature, refinement martensite/bainite colony size, so Ni has the function that simultaneously improves hardened and tempered steel plate intensity, unit elongation and low-temperature flexibility; In steel, add the copper brittleness phenomenon that Ni can also reduce Copper Bearing Steel, alleviate the intergranular cracking of course of hot rolling, improve the resistance to atmospheric corrosion of steel plate, and Ni is low to carbon equivalent contribution margin.Therefore theoretically, in steel, Ni content is more high better within the specific limits, and the welded heat affecting zone but too high Ni content can harden is unfavorable to the weldability of steel plate and welding joint SR performance; Ni is a kind of very noble element simultaneously, from the ratio of performance to price, considers, Ni content is controlled between 0.10%～0.40%, does not damage the weldability of steel plate to guarantee the hardening capacity of steel plate and the obdurability level of steel plate.

Cr is as weak carbide forming element, add hardening capacity, the formation of promotion martensite/bainite that Cr not only improves steel plate, and between martensite/lath of bainite, position increases to poor, increase crackle through the resistance of martensite/bainite colony, when improving armor plate strength, the have some improvement effect of steel plate toughness of tool; Yet when Cr addition is super when many, separate out the carbide of thick chain chromium in drawing process on original austenite crystal prevention, deteriorated hardened and tempered steel plate low-temperature impact toughness, the more important thing is the weldability of grievous injury steel plate; Therefore Cr content is controlled between 0.10%～0.30%.

Add the hardening capacity of Mo raising steel plate, promote martensite/bainite to form, but Mo is as carbide, when promoting that martensite/bainite forms, increase position between the size of martensite/bainite colony and the martensite/lath of bainite of formation and, to poor very little, reduce crackle through the resistance of martensite/bainite colony; Therefore Mo, when increasing substantially hardened and tempered steel plate intensity, has reduced low-temperature flexibility, unit elongation and the weldability of hardened and tempered steel plate; The more important thing is when Mo addition surpasses 0.30%, increase considerably the manufacturing cost of hardened and tempered steel plate.Therefore consider phase transformation strengthening effect and the impact on mother metal steel plate low-temperature flexibility, unit elongation, weldability and manufacturing cost of Mo, the present invention adopts ultralow Mo alloying, and Mo content is controlled at 0.05%～0.30%.

B content is controlled between 0.0006%～0.0013%, when guaranteeing hardened and tempered steel plate hardening capacity, does not damage weldability and the HAZ toughness of steel plate.

Ti content, between 0.005%～0.011%, suppresses Austenite Grain Growth in heating of plate blank, course of hot rolling, improves hardened and tempered steel plate low-temperature flexibility, the more important thing is and suppresses HAZ grain growth in welding process, improves HAZ toughness; When Ti content surpasses 0.011% in addition, the TiN particle of formation is not only more but also comparatively thick, has the ferrite of promotion and forms, and has a strong impact on the hardening capacity in hardened and tempered steel plate centre.

Als in steel is the freedom [N] in steel fixedly, reduces welded heat affecting zone (HAZ) freely [N], improve the low-temperature flexibility effect of welded H AZ, so Als lower limit is controlled at 0.035%; But in steel, add excessive Als not only can cause casting difficulty, 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 0.065%.

The span of control of N is corresponding with the span of control of Ti, and for the hardened and tempered steel plate of superior weldability, N content is too low, and generation TiN number of particles is few, size is large, can not play the effect of the weldability of improving quenched and tempered steel, harmful to weldability on the contrary; But during N too high levels, in steel, freely [N] increases, heat affected zone (HAZ) freely [N] content increases, grievous injury HAZ low-temperature flexibility, the weldability of deterioration quenched and tempered steel.Therefore N content is controlled at below 0.0060%.

V content is between 0.015%～0.045%, and along with the increase of steel plate thickness, V content is capping value suitably.Adding V object is to separate out in bainite/martensite lath by V (C, N), improves the intensity of hardened and tempered steel plate.V adds very few, and lower than 0.015%, the V (C, N) separating out very little, can not effectively improve the intensity of hardened and tempered steel plate; V addition is too much, higher than 0.045%, and infringement hardened and tempered steel plate low-temperature flexibility, unit elongation and weldability.

Steel is carried out to Ca processing, on the one hand can further pure molten steel, on the other hand steel medium sulphide content is carried out to denaturing treatment, make it the anisotropy that becomes non deformable, to stablize tiny spherical sulfide, inhibition S red brittleness, low-temperature flexibility, unit elongation and the Z-direction performance of raising steel, improves steel plate toughness.The number of Ca add-on, depends on the height of S content in steel, and Ca add-on is too low, and treatment effect is little; Ca add-on is too high, forms Ca (O, S) oversize, and fragility also increases, and can become fracture crack starting point, reduces low-temperature flexibility and the unit elongation of steel, also reduces purity of steel simultaneously, pollutes molten steel.General control Ca content is pressed ESSP=(wt%Ca) [1-1.24 (wt%O)]/1.25 (wt%S), wherein ESSP is sulfide inclusion shape control index, between span 0.5～5, be advisable, so the OK range of Ca content is 0.0010%～0.0040%.

The manufacture method of low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plates of the present invention, it comprises the steps:

1) smelt, cast

According to mentioned component, smelt, be cast into slab; Low temperature casting in casting employing, pouring temperature is controlled between 1530～1560 ℃, and the pure Ar time >=2min that blows of ladle before casting, and the calm time >=2min of ladle, guarantees inclusion floating removal;

2) rolling

Heating of plate blank, heating and temperature control between 1050～1150 ℃, soaking time 3～6 hours, when guaranteeing the inner segregation diffusion of the solid solution of slab microalloy carbonitride, slab homogenizing, original austenite grains is within reason grows up;

First stage is common rolling, adopts milling train maximum capacity to carry out continuous rolling incessantly; Guarantee that dynamically/Static Recrystallization, refine austenite crystal grain occur deformation metal;

Subordinate phase adopts recrystallize controlled rolling, 900～950 ℃ of start rolling temperatures, rolling pass draft >=8%, accumulative total draft >=50%, 800～850 ℃ of finishing temperatures;

3) cooling

Thickness≤40mm steel plate, after rolling, natural air cooling is to room temperature; Finished steel plate thickness G reatT.GreaT.GT 40mm adopts slow cooling dehydrogenating technology, and retarded cooling process is that steel plate is at least incubated 24 hours above at 300 ℃;

4) thermal treatment

Quench, steel plate quenching temperature is that plate temperature is 880～920 ℃, the hold-time >=15min that quenches, and the hold-time of quenching is the soaking time that steel plate core temperature starts timing while reaching quenching target temperature;

Tempering, steel plate tempering temperature is that plate temperature is 530～630 ℃, tempering hold-time >=25min, the tempering hold-time is the soaking time that steel plate core temperature starts timing while reaching tempering target temperature.

Beneficial effect of the present invention:

The present invention combines with special hardening and tempering process (RCR+QT) by the unitized design of steel plate alloying element, when obtaining excellent low-temperature flexibility, high strength (tensile strength >=780MPa), unit elongation δ 5 >=15%, steel plate has ultralow carbon equivalent Ceq, good weldability, the more important thing is and realize quenching and tempering, high plate low cost fabrication, low welding processing cost of manufacture; And the comprehensive mechanical property that has successfully solved high-strength hardened and tempered steel plate conflicts in Composition Design, technological design mutually with manufacturing cost, welding processing cost of manufacture, the very difficult problem being in harmonious proportion; The more important thing is that manufacturing cost is relatively cheap, make the high-strength hardened and tempered steel plate of 80 feather weight of characteristic good promote and be promoted greatly to industries such as the engineering machinery having a large capacity and a wide range, bridge structure, automotive industry and transportation by railroads, accelerated the upgrading that these industries are used; In addition, good weldability, the high-strength hardened and tempered steel plate without preheating welding of 80 feather weight, postwelding have been realized without heat treatment process manufacture craft, saved the cost that user's steel member is manufactured, shortened the time that user's steel member is manufactured, for user has created huge value, thereby this type of steel plate is not only the product of high added value, green environmental protection.

Accompanying drawing explanation

Fig. 1 is the microstructure of the embodiment of the present invention 3 steel.

Embodiment

Below in conjunction with embodiment, the present invention will be further described.

Table 1 is depicted as the composition of embodiment of the present invention steel, and table 2 is the manufacturing process of embodiment of the present invention steel.Table 3, table 4 are the performance of embodiment of the present invention steel.

From Fig. 1 and table 3, table 4, can find out, the microstructure of steel plate of the present invention is tiny tempered martensite+tempering lower bainite, and average colony size, below 25 μ m, obtains evenly good obdurability.

In sum, the present invention combines with special hardening and tempering process (RCR+QT) by the unitized design of steel plate alloying element, when obtaining at the same time good mother metal steel plate low-temperature flexibility, high strength and weldability, steel plate cheap for manufacturing cost, and the problem that is in harmonious proportion is mutually conflicted, is difficult to the over-all properties that has successfully solved high-strength hardened and tempered steel plate in Composition Design, technological design with manufacturing cost; And due to cheap for manufacturing cost, make high-strength hardened and tempered steel plate promote and be promoted greatly to industries such as the engineering machinery having a large capacity and a wide range, bridge structure, automotive industry and transportation by railroads, accelerated the upgrading that these industries are used; In addition, cheap steel plate manufacturing cost and good weldability have been saved the cost that user's steel member is manufactured, and have shortened the time that user's steel member is manufactured, and for user has created huge value, thereby this type of steel plate is not only the product of high added value, green environmental protection.

80 feather weight hardened and tempered steel plates are critical materials that the industries such as engineering machinery, mining machinery, heavy equipment framework, bridge structure, automotive industry and transportation by railroad update; But the general manufacturing cost of 80 feather weight quenched and tempered steel of high strength, high tenacity and superior weldability is expensive, be difficult to promote to industries such as the engineering machinery having a large capacity and a wide range, mining machinery, heavy equipment framework, bridge structure, automotive industry and transportation by railroads, 80 feather weight hardened and tempered steel plates are used and are subject to great restriction in these industries, have affected the design and the employing of manufacturing update and new technology, novel process of these industry equipment.Along with Chinese national economy development, the requirement of building saving, environmentally friendly harmonious society, reduces resource consumption, improves resource utilization and has put day thing agenda.

The present invention's 80 feather weight high-performance hardened and tempered steel plates being widely used in these industries, not only can significantly reduce steel usage quantity, reduce per GDP consumed resource, and minimizing processing, Production Time and cost, use quickening that the more important thing is these high performance materials promotes China's weight equipment production scientific-technical progress, promotes whole industry international competitiveness.

Claims (2)

1. low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plates, its composition weight percent is:

C：0.05%～0.12%

Si：≤0.20%

Mn：1.20%～1.60%

P：≤0.013%

S：≤0.003%

Cu：0.10%～0.30%

Ni：0.10%～0.40%

Cr：0.10%～0.30%

Mo：0.05%～0.30%

Als：0.035%～0.065%

Ti：0.005%～0.011%

V：0.015%～0.045%

N：≤0.0060%

Ca：0.001%～0.004%

B：0.0006%～0.0013%

All the other are iron and inevitable impurity;

And above-mentioned constituent content must meet following relation simultaneously:

Mn/C≥12；

Als≥12×[(%N _total)－0.292(%Ti)]；

Control Ceq≤0.43%;

(%Si)×(%C)≤0.012；

Mo equivalent >=0.30%, Cr equivalent >=0.40%; Mo equivalent=Mo+0.67Cr+0.83Si+1.62V wherein; Cr equivalent=Cr+1.21Mo+Si+1.86V;

Ni/Cu≥0.50；

Ca/S is between 1.00～3.00, and (%Ca) * (%S) ^0.18≤ 2.5 * 10 ^-3;

Control F * DI index>=1.2 * t, wherein F is B element hardening capacity contribution factor; While there is solid solution [B] in steel, F gets 1.2; T is finished steel plate thickness, the mm of unit; DI=0.367 (%C) ^0.5[1+0.7 (%Si)] [(1+3.33 (%Mn)] [(1+0.35 (%Cu)] [(1+0.36 (%Ni)] [(1+2.16 (%Cr)] [(1+3 (%Mo)] [(1+1.75 (%V)] [(1+1.77 (%Al)] * 25.4, the mm of unit.

2. the manufacture method of low-carbon-equivalent 80 feather weight high-performance hardened and tempered steel plates as claimed in claim 1, it comprises the steps:

1) smelt, cast

According to mentioned component, smelt, be cast into slab; Low temperature casting in casting employing, pouring temperature is controlled between 1530～1560 ℃, and the pure Ar time >=2min that blows of ladle before casting, and the calm time >=2min of ladle, guarantees inclusion floating removal;

2) rolling

Heating of plate blank, heating and temperature control between 1050～1150 ℃, soaking time 3～6 hours;

First stage is common rolling, adopts milling train maximum capacity to carry out continuous rolling incessantly;

Subordinate phase adopts recrystallize controlled rolling, 900～950 ℃ of start rolling temperatures, rolling pass draft >=8%, accumulative total draft >=50%, 800～850 ℃ of finishing temperatures;

3) cooling

Thickness≤40mm steel plate, after rolling, natural air cooling is to room temperature; Finished steel plate thickness G reatT.GreaT.GT40mm adopts slow cooling dehydrogenating technology, and retarded cooling process is that steel plate is at least incubated 24 hours above at 300 ℃;

4) thermal treatment

Quench, steel plate quenching temperature is that plate temperature is 880～920 ℃, the hold-time >=15min that quenches, and the hold-time of quenching is the soaking time that steel plate core temperature starts timing while reaching quenching target temperature;

Tempering, steel plate tempering temperature is that plate temperature is 530～630 ℃, tempering hold-time >=25min, the tempering hold-time is the soaking time that steel plate core temperature starts timing while reaching tempering target temperature.