CN103422021A - Low-yield-ratio structural steel with yield ratio equal to or larger than 550MPa and manufacturing method thereof - Google Patents
Low-yield-ratio structural steel with yield ratio equal to or larger than 550MPa and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses low-yield-ratio structural steel with a yield ratio equal to or larger than 550MPa. The low-yield-ratio structural steel with the yield ratio equal to or larger than 550MPa comprises, by weight, 0.03-0.10% of C, 0.30-0.60% of Si, 1.40-2.00% of Mn, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.10-0.50% of Mo, 0.10-0.40% of Cr, 0.040-0.10% of Nb, 0.008-0.025% of Ti, 0.015-0.055% of Als, 0.0010-0.0080% of Ca, 0.0005-0.0050% of Mg, 10-30*10<-4>% of N, and 5-25*10<-4>% of O. A manufacturing method of the low-yield-ratio structural steel with the yield ratio equal to or larger than 550MPa comprises the steps of carrying out smelting and continuous casting to form a blank, heating the casting blank and carrying out heat insulation on the casting blank, rough rolling, finish rolling, and carrying out relaxation slow cooling on a steel plate. The mechanical properties of the low-yield-ratio structural steel are that RP0.2>=550Mpa, Rm>=700MPa, ductility A>=25%, -20 DEG C KV2>=200J, and RP0.2 / Rm <= 0.80. According to the low-yield-ratio structural steel with the yield ratio equal to or larger than 550MPa and the manufacturing method thereof, preheating is not needed after welding or the preheating temperature is not larger than 50DEG C, heat treatment is not needed after welding, and therefore welding efficiency is greatly improved; the cold and hot machining performance is good, and resistance to large deformation is achieved; cost is low, and the manufacturing processes are simplified.
Description
Technical field
The present invention relates to a kind of Kind of Steels Used in Engineering Structures and production method thereof, belong to particularly low yield strength ratio structural steel and the production method thereof of yield strength >=550MPa.
Background technology
Traditional high-strength steel generally takes the mode of quenching+tempering to produce, when intensity improves, yield tensile ratio is also improving constantly, especially reach 600MPa when above when tensile strength, its yield tensile ratio just reaches more than 0.90, plasticity index also drops to below 20%, consideration based on secure context, bridge, pipeline, construction work all limits the yield tensile ratio of steel plate to some extent with steel, especially Highrise buildings and public heavy construction must have good shock resistance, yield tensile ratio (below 0.85) and the plasticity index (more than 20%) that uses steel had to strict restriction, obviously, higher yield tensile ratio and the lower unit elongation of tradition high-strength steel limited these class steel applying in such engineering.And in recent years, the steel plate that once had bibliographical information to adopt two-phase region quenching+tempering mode to produce meets the technical requirements of such engineering, its metallographic structure type is ferrite+martensite, utilizes the rational proportion of soft phase ferritic structure to reach the purpose of low yield strength ratio.The deficiency of its existence is that the process of thermal treatment window is narrower, wayward in actual production, even needs to carry out repeatedly heat treatment process, has greatly extended the technological process of production, has increased production cost, is unfavorable for applying.
Through retrieving: the patent documentation that Chinese Patent Application No. is 200910061106.1, a kind of high strength low yield ratio welding structure steel and production method thereof are disclosed, its deficiency is to contain the precious alloy elements such as higher Cr, Ni, and need to carry out the stress relief tempering processing, the unit elongation of steel plate is not done to requirement yet.
The patent documentation that Chinese Patent Application No. is 201010599469.3, disclose a kind of 800MPa level low yield strength ratio structural steel and iron and production method thereof, this steel must contain more Cu, Ni element, and cost of alloy is high, and steel plate must carry out temper, has increased the explained hereafter cost.
The patent documentation that the patent No. is EP20010930007, " THICK STEEL PLATE BEING EXCELLENT IN CTOD CHARACTERISTIC IN WELDING HEAT AFFECTED ZONE AND HAVING YIELD STRENGTH OF 460MPa OR MORE " disclosed, this invention steel adopts direct quenching+tempering or TMCP operational path to produce, but the steel plate that adopts direct quenching+tempering to produce only has the part yield strength more than 550MPa, and yield tensile ratio is between 0.84-0.90, do not have anti-seismic performance, the production technique cost is also higher; The steel plate yield strength that adopts TMCP to produce is all below 550MPa, and intensity rank is lower, and its yield tensile ratio is between 0.79-0.88, and anti-seismic performance is poor.The steel plate of above-mentioned two kinds of explained hereafter is all limited the Mg of unit surface and the oxide particle number of Al, controls difficulty larger, is unfavorable for promoting and producing at each metallurgy industry.
Summary of the invention
The object of the invention is to overcome the deficiency that prior art exists, a kind of R is provided
P0.2>=690MPa, Rm>=800MPa, unit elongation A>=22% ,-20 ℃ of KV
2>=180J, R
P0.2/ Rm≤0.80, and production process is simple, and cost is low, is easy to low yield strength ratio structural steel and the production method thereof of the yield strength>=690MPa of scale operation.
Realize the technical measures of above-mentioned purpose:
The low yield strength ratio structural steel of a kind of yield strength>=550MPa, its component and weight percent content are: C:0.03-0.10%, Si:0.30-0.60%, Mn:1.40-2.00%, P≤0.010%, S≤0.005%, Mo:0.10-0.50%, Cr:0.10-0.40%, Nb:0.040-0.10%, Ti:0.008-0.025%, Als:0.015-0.055%, Ca:0.0010-0.0080%, Mg:0.0005-0.0050%, N:10-30 * 10
-4%, O:5-25 * 10
-4%, all the other are Fe and inevitable impurity; Meet: Ca/S=1.2-2.8,2Cr+Mn=2.00-2.60%, Als/N=12-20, Pcm=C+Si/30+Mn+Cu+Cr simultaneously)/20+Ni/60+Mo/15+V/10+5B≤0.25%; Mechanical property is: R
P0.2>=550MPa, Rm>=700MPa, unit elongation A>=25% ,-20 ℃ of KV
2>=200J, R
P0.2/ Rm≤0.80.
It is: being added with weight percent content is: V≤0.10%, Ni≤0.30%, B≤0.0020%.
Produce the method for the low yield strength ratio structural steel of a kind of yield strength >=550MPa, it walks Zou:
1) smelt also continuous casting and become base;
2) strand heated and be incubated, heating and temperature control is at 1180 ~ 1220 ℃;
3) carry out roughing: 1160-1180 ℃, total reduction is 60-80%, and the roughing end temp is 1040-1080 ℃;
4) carry out finish rolling: control finishing temperature at 800 ~ 860 ℃, total reduction is 70～80%, and rolling pass is in 6 ~ 8 roads;
5) steel plate is carried out to the relaxation slow cooling, speed of cooling is 2-5 ℃/s, and cooling termination temperature is 740-820 ℃; Carry out subsequently laminar flow cooling, speed of cooling is 10-20 ℃/s, and cooling termination temperature is 300-500 ℃; Last air cooling is to room temperature.
It is characterized in that: the cooling upper and lower water of laminar flow is than being 0.50-0.85, and roller speed is 0.5-1.4m/s.
Below mechanism and the effect of chemical composition and main technique in detailed description the present invention:
C content of the present invention is chosen in 0.03～0.10%, C and replaces by gap the intensity that solution strengthening improves steel strongly, is to guarantee one of requisite element of hardness of steel.C belongs to and enlarges austenite phase block elements, when C content lower than 0.03% the time,
Transformation temperature obviously promotes, and causes the TMCP process window narrow, and causes the raising of steel strength deficiency and yield tensile ratio.When C content, higher than 0.10% the time, the welding cold crack sensitivity coefficient of the tendency of carbon segregation, Gang Zhong M-A island amount and steel increases, thereby worsens plasticity and toughness and the welding property of steel, affects the cold and hot working performance of steel.Therefore C content is defined as 0.03～0.10%.
It is solution strengthening and deoxidation that Si content of the present invention is chosen in the Main Function of 0.3～0.60%, Si in steel.Owing to adding Mg, Ca, Als etc. and [O], the element of stronger bonding force is arranged, therefore, Si is mainly solution strengthening effect in steel of the present invention.When Si content, lower than 0.3% the time, its solution strengthening effect is not obvious, and especially tensile strength can not meet the demands, cause yield tensile ratio to raise simultaneously, higher than 0.60% the time, the ratio on welded heat affecting zone MA island be will increase when Si content, base material and HAZ low-temperature impact toughness and ductility worsened.Therefore Si content is defined as 0.3-0.60%.
Mn content of the present invention is chosen in 1.40～2.0%, Mn and guarantees steel obdurability and the indispensable element of welded heat affecting zone performance.Another vital role of Mn is the forming core core that the tiny sulfide that forms with Ca, S can be used as acicular ferrite, and when Mn content, lower than 1.4% the time, these effects are limited; Higher than 2.0% the time, can form the sulfide inclusion of more large size complexity when Mn content, reduce the low temperature fracture toughness of steel and the low-temperature flexibility of welded heat affecting zone, worsen the welding property of steel.Simultaneously, Mn enlarges the austenite phase region, reduces A
C1And A
C3Transformation temperature, higher than 3.50% the time, suppress ferritic transformation when Mn content, proper temperature start cooling fast after, will cause the ferritic transformation amount seldom, the yield strength of steel will sharply raise, and be unfavorable for that yield tensile ratio controls.Therefore Mn content is defined as 1.4～2.0%.
P of the present invention≤0.010%, S≤0.005%, P, S are the detrimental impurity elements in steel.High P easily causes segregation,
Affect the homogeneity of structure of steel, reduce the toughness of steel; S and Mn easily form MnS and are mingled with, very unfavorable to low-temperature flexibility.
Mo content of the present invention is selected in 0.10-0.50%, and the effect of Mo in steel is mainly solution strengthening effect, and a small amount of Mo separates out with the form of carbide, further improves the intensity of steel.Mo is the stabilization of austenite element, promotes the bainite and martensite of high density dislocation substructure to form, and utilizes build up to improve the intensity of steel, and appropriate Mo can also reduce the yield tensile ratio of steel, improves the anti-seismic performance of steel.Want to reach above-mentioned effect, Mo content must not be less than 0.10%, but Mo is precious alloy
Element, the Mo over 0.50% not only, easily obtaining a large amount of martensitic stuctures in process of cooling fast, also easily obtains martensitic stucture in welding is cooling, has worsened the over-all properties of base material and heat affected zone.
Cr content of the present invention is selected in 0.1-0.4%, Cr is the element that effectively improves armor plate strength, it is also the element that improves steel plate hardening capacity, make the ferritic phase apparition move to right, widen the cooling rate interval of bainitic transformation, promote the formation of middle temperature transformation tissue, simultaneously, in the situation of Cr and the compound interpolation of Ni, more contribute to improve hardening capacity and the weather resistance of steel.But, when Cr content surpasses 0.40%, can significantly reduce the toughness of base material and heat affected zone.
Ni content of the present invention is chosen in≤and 0.30%, Ni is little to the steel strength contribution, but can obviously improve steel
Low-temperature flexibility, significantly improve the low-temperature flexibility of steel.Particularly, to high steel of solution strengthening constituent content such as Cr, its effect that improves low-temperature flexibility is just more obvious.The Ni amount is too high, and except increasing production cost, surface of steel plate easily produces the iron scale that is difficult to come off.
Nb content of the present invention is chosen in 0.04～0.10%, Nb is a kind of carbide, there is strong Grain refinement, can significantly improve austenite recrystallization temperature, enlarge the rolling technology scope, make invention steel abundant thinning microstructure in II stage rolling process, guarantee that steel have good obdurability coupling.In the operation of rolling, the carbonitride particle that Nb forms in steel, can effectively suppress growing up of austenite crystal, improves obdurability and ductility.In steel of the present invention, when Nb content, lower than 0.04% the time, cause the yield strength deficiency, when Nb content, higher than 0.10% the time, welded heat affecting zone will worsen its performance because of the appearance of MA island tissue in the welding process of cooling.
V of the present invention≤0.10%, V is a kind of quite strong carbide forming element, appropriate V has obvious precipitation hardening effect.As Nb and V is compound adds fashionablely, can obviously improve the generation of transverse crack phenomenon, significantly improve the recrystallization temperature of steel.But the V too high levels, the precipitation strength effect is remarkable, but base material and heat affected zone toughness variation.
Ti of the present invention is chosen in 0.008～0.025%, Ti is also a kind of strong carbonitride forming element, separate out tiny TiN, Ti(CN on Mg, Als superfine oxide particle) or Nb the composite carbon nitride of Ti, the effective dimensions of these particles is below 1.0 μ m, can effectively stop Austenite Grain Growth in heating and welding process, make grain refining, improve the low-temperature flexibility of steel.Ti and Nb add simultaneously, can further improve the steel austenite recrystallization temperature, enlarge the rolling technology scope.But when Ti is greater than 0.025%, the carbonitride particle size of the Ti separated out will reach several even tens μ m orders of magnitude, cause the inadequate refinement of crystal grain, worsen the toughness of base material and welded heat affecting zone, when Ti is less than 0.008%, unit surface endoparticle quantity not sufficient, do not have grain refinement effect, therefore Ti is defined as 0.008～0.025%.
Als content of the present invention is chosen in 0.015～0.055%, Als and usually adds in steel as deoxidant element.Als N in steel is combined and is formed the AlN particle, improves intensity and the low-temperature flexibility of steel by Grain Refinement Effect.Als in the present invention
Another vital role and Mg and [O] are in conjunction with forming fine oxide particle, Mn sulfide depends on these oxide particles and separates out, the tiny precipitate of this complexity can be used as again grain boundary ferrite and the ferritic forming core core of lath, thus refinement base material and HAZ tissue.If Als content is lower than 0.010%, form the TiN amounts of particles in steel and as the oxide particle deficiency of forming core core, worsen base material and HAZ impelling strength, if Als content is higher than 0.055% the time, easily cause that in steel, the oxide inclusion of Al increases, size is larger, reduces purity and the plasticity and toughness of steel, worsens welding heat affected impelling strength.
Ca of the present invention is deoxidant element, is also the desulfurization element, and its content is controlled at 0.001～0.008%.Add appropriate Ca in steel by the Sulfide inclusion nodularization, be conducive to improve low-temperature flexibility and the HAZ toughness of base material.In order to improve its deoxidization desulfuration effect, improve base material quality and heat affected zone performance, Ca content should be not less than 0.001%; When Ca content surpasses 0.008%, can form many large-scale oxide compounds containing Ca and sulfide mixing and be mingled with, be unfavorable for the impelling strength of base material and heat affected zone.
Mg of the present invention is controlled at 0.0005～0.005%.Mg is a very important element in product of the present invention.Mg and Als and [O] be in conjunction with forming tiny oxide particle, and TiN take that it separates out tiny complex granule as the forming core core depends on these oxide surfaces, refinement base material and heat affected zone tissue; Mg can also accelerate the MnS inclusion and separate out complicated particle on these oxide compounds, as changing core so refinement base material and heat affected zone tissue.In steel, Mg content is lower than 0.0005% the time, in these oxide compound complex granules, Mg content is lower, MnS is difficult to separate out on the oxide particle of Mg, also just lost its effect as intracrystalline ferritic transformation core, while, the low-temperature flexibility of base material and HAZ toughness can not get ensureing as the unit surface oxide particle quantity not sufficient of the forming core core of TiN.When Mg content is 0.005%, the effect of Mg reaches capacity, even the content of Mg surpasses 0.005%, forms the high large size complex inclusion of Mg content, worsens the impelling strength of base material and heat affected zone.
B of the present invention selects to add and is no more than 0.002%, the effect of B is mainly the hardening capacity that improves steel, postpones austenite and changes to ferrite and pearlite, when B content surpasses 0.002%, to cause low-temperature impact toughness decline and unstable, worsen the welding property of steel simultaneously.
N content of the present invention is chosen in 10～30 * 10
-4%, in N and steel, the elements such as Nb, Ti, Al, V, C form nitride or carbonitride, are the important elements that makes steel mother metal tissue and weld structure grain refining.If N content is lower than 10 * 10
-4%, in N and steel, Ti, Als form unit nitride particles quantity not sufficient, effectively refinement base material and weld structure.When N content higher than 30 * 10
-4During %, in steel, solid solution N amount increases, unfavorable to base material and welded heat affecting zone performance, also is unfavorable for the surface quality of steel billet.
O content of the present invention is chosen in 5～25 * 10
-4%, generally, O belongs to obnoxious flavour in steel, for guaranteeing the total amount of oxide inclusion in purity of steel and steel, O content strictly need be limited in to lower level.But work as O content lower than 5 * 10
-4During %, in steel unit surface as the fine oxide amounts of particles deficiency of Mg, the Als of forming core core.For avoiding in steel occurring too much oxide-based large size complex inclusion, in steel, the O upper content limit is limited in 25 * 10
-4In %.
Above-mentioned chemical composition also must meet simultaneously: Ca/S=1.2-2.8, Als/N=12-20,2Cr+Mn=2.0-2.6%, Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B≤0.25%.
In steel of the present invention, when Ca/S<1.2, Ca is not obvious to the rotten spheroidization of Sulfide inclusion, when Ca/S>2.8, will form many large-scale oxide compound and sulfide mixing inclusiones containing Ca in steel, is unfavorable for the performance of steel;
When Als/N<12, unit surface AlN amounts of particles deficiency, its Grain refinement is not obvious, when Als/N>20, contains the large size aluminate in steel, and the performance of base material and heat affected zone is all had a negative impact;
When 2Cr+Mn<2.0%, cause the hardness of steel deficiency, when 2Cr+Mn>2.6%, worsen base material and heat affected zone; Steel of the present invention belongs to the high ductile steel of high-strong toughness, is intensity and the welding property of guaranteeing steel, and the Pcm value must be less than or equal to 0.25%.
The reason that main technologic parameters is controlled:
For making the abundant austenitizing of strand, Mo, Cr are dissolved in austenite sufficiently uniformly simultaneously, must be by strand 1180 ~ 1220 ℃ of heating, when temperature during lower than 1180 ℃, must increase heat-up time, increase cost, Cr and Mo can not be dissolved in austenite fully simultaneously, reduced its effect, also made each position intensity inequality of steel plate; During higher than 1260 ℃, will obtain thick austenite crystal when temperature, cause not section of intensity, worsen low-temperature flexibility, also worsen the welding property of steel.
Steel is carried out to roughing in complete austenitic area, for obtaining the austenite crystal of abundant refinement, adopt the 3-5 passage to depress greatly, must guarantee that total reduction is 60-80%, the control finishing temperature is 1040-1080 ℃, when temperature during lower than 1040 ℃, easily obtain mixed grain structure, when temperature, higher than 1080 ℃, before finish rolling, the waiting time is long, austenite is grown up, and easily causes undercapacity.
Finish rolling, in complete non-recrystallize stage rolling, for guaranteeing finish rolling stage percentage pass reduction, obtains abundant thinning microstructure, and rolling pass is restricted to the 6-8 road, and total reduction is 70-80%, and finishing temperature is 800-860 ℃.
The steel plate relaxation time is less than or equal to 10s, and speed of cooling is 2-5 ℃/s, and cooling termination temperature is 740-820 ℃, and when the relaxation time is greater than 10s, the proeutectoid ferrite grain growth, cause undercapacity; When speed of cooling, during lower than 2 ℃/s, relaxation time that need to be longer could be chilled to 740-820 ℃ by steel billet temperature, grain coarsening, and when higher than 5 ℃/s, the proeutectoid ferrite scale of construction is very few does not even have ferrite to separate out, and causes the steel plate yield tensile ratio higher than 0.80.
The cooling beginning temperature of laminar flow subsequently is 740-820 ℃, and the laminar flow speed of cooling is 10-20 ℃/s, and cooling termination temperature is 300-500 ℃; Last air cooling is to room temperature.When cooling beginning temperature is less than 740 ℃, have a large amount of ferrites and separate out, cause undercapacity; When cooling beginning temperature, during higher than 820 ℃, in steel, without ferrite, separate out, yield tensile ratio is higher, and unit elongation sharply descends, and can not meet steel requirement of the present invention.During lower than 10 ℃/s, occur pearlitic structure when speed of cooling in steel, cause the low-temperature flexibility variation of steel, worsen the welding property of steel; During higher than 20 ℃/s, occur a large amount of martensitic stuctures when speed of cooling in steel, worsen the welding property of steel.For tissue and the splendid steel plate of performance that obtains abundant refinement, cooling termination temperature is controlled as 300-500 ℃.In order to ensure the steel plate template, performance is uniform and stable and obtain good comprehensive mechanical performance, must control the cooling upper and lower water of laminar flow than being 0.50-0.85, roller speed is 0.5-1.4m/s.
What deserves to be explained is, through validation trial, strictly adopt the steel plate of chemical composition of the present invention, rolling technological parameter and the manufacture of process for cooling parameter could meet steel requirement of the present invention.
The present invention compared with prior art mechanical property is: R
P0.2>=550MPa, R
m>=700MPa, unit elongation A>=25% ,-20 ℃ of KV
2>=200J, R
P0.2/ R
m≤ 0.80; And postwelding does not need preheating or preheating temperature not higher than 50 ℃, and postwelding does not need thermal treatment, has greatly improved welding efficiency; There is good cold and hot working performance, there is Chinese People's Anti-Japanese Military and Political College's resistance to deformation; Steel of the present invention is non-hardened and tempered steel, has with low costly, and manufacturing process is simple.
The accompanying drawing explanation
Accompanying drawing is metallographic structure figure of the present invention.
Embodiment
Below the present invention is described further
Table 1 is various embodiments of the present invention and the list of Comparative Examples chemical composition value;
Table 2 is various embodiments of the present invention and the list of Comparative Examples main technologic parameters value;
The mechanical property test result that table 3 is the embodiment of the present invention.
Embodiment is according to following steps production:
1) smelt also continuous casting and become base;
2) strand heated and be incubated, heating and temperature control is at 1180 ~ 1220 ℃;
3) carry out roughing: 1160-1180 ℃, total reduction is 60-80%, and the roughing end temp is 1040-1080 ℃;
4) carry out finish rolling: control finishing temperature at 800 ~ 860 ℃, total reduction is 70～80%, and rolling pass is in 6 ~ 8 roads;
5) steel plate is carried out to the relaxation slow cooling, speed of cooling is 2-5 ℃/s, and cooling termination temperature is 740-820 ℃; Carry out subsequently laminar flow cooling, speed of cooling is 10-20 ℃/s, and cooling termination temperature is 300-500 ℃; Last air cooling is to room temperature.
The chemical composition (wt, %) of table 1 various embodiments of the present invention and Comparative Examples steel
Chemical composition contrast (wt, %) (two) of table 1 steel of the present invention
Table 2 various embodiments of the present invention and Comparative Examples main technologic parameters value list ()
Table 2 various embodiments of the present invention and Comparative Examples main technologic parameters value list (two)
The mechanical property list of table 3 various embodiments of the present invention and Comparative Examples
As can be seen from Table 3, through steel plate of the present invention being carried out to normal tensile property ,-20 ℃ of impact of collision tests, and contrast with compared steel, its result: under normal temperature, steel yield strength of the present invention and compared steel are in same level, and tensile strength exceeds much than compared steel, steel yield tensile ratio (R of the present invention
EL/ R
m) all be less than 0.80 and higher extension property, and the comparative steel yield tensile ratio is more than 0.86, unit elongation is below 20%, and this explanation steel of the present invention has more excellent anti-seismic performance and extension property; Steel of the present invention-20 ℃ lower ballistic work is all in the 300J left and right, and far above compared steel, this explanation steel of the present invention has excellent low-temperature flexibility.
Above-described embodiment only exemplifies for the best, and is not the restriction to embodiments of the present invention.
Claims (4)
1. the low yield strength ratio structural steel of a yield strength>=550MPa, its component and weight percent content are: C:0.03-0.10%, Si:0.30-0.60%, Mn:1.40-2.00%, P≤0.010%, S≤0.005%, Mo:0.10-0.50%, Cr:0.10-0.40%, Nb:0.040-0.10%, Ti:0.008-0.025%, Als:0.015-0.055%, Ca:0.0010-0.0080%, Mg:0.0005-0.0050%, N:10-30 * 10
-4%, O:5-25 * 10
-4%, all the other are Fe and inevitable impurity; Meet: Ca/S=1.2-2.8,2Cr+Mn=2.00-2.60%, Als/N=12-20, Pcm=C+Si/30+Mn+Cu+Cr simultaneously)/20+Ni/60+Mo/15+V/10+5B≤0.25%; Mechanical property is: R
P0.2>=550MPa, Rm>=700MPa, unit elongation A>=25% ,-20 ℃ of KV
2>=200J, R
P0.2/ Rm≤0.80.
2. the low yield strength ratio structural steel of a kind of yield strength >=550MPa as claimed in claim 1, it is characterized in that: being added with weight percent content is: V≤0.10%, Ni≤0.30%, B≤0.0020%.
3. produce the method for the low yield strength ratio structural steel of a kind of yield strength >=550MPa claimed in claim 1, it walks Zou:
1) smelt also continuous casting and become base;
2) strand heated and be incubated, heating and temperature control is at 1180 ~ 1220 ℃;
3) carry out roughing: 1160-1180 ℃, total reduction is 60-80%, and the roughing end temp is 1040-1080 ℃;
4) carry out finish rolling: control finishing temperature at 800 ~ 860 ℃, total reduction is 70～80%, and rolling pass is in 6 ~ 8 roads;
5) steel plate is carried out to the relaxation slow cooling, speed of cooling is 2-5 ℃/s, and cooling termination temperature is 740-820 ℃; Carry out subsequently laminar flow cooling, speed of cooling is 10-20 ℃/s, and cooling termination temperature is 300-500 ℃; Last air cooling is to room temperature.
4. the method for the low yield strength ratio structural steel of a kind of yield strength >=550MPa as claimed in claim 3 is characterized in that: the cooling upper and lower water of laminar flow is than being 0.50-0.85, and roller speed is 0.5-1.4m/s.
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| CN105063509A (en) * | 2015-07-27 | 2015-11-18 | 武汉钢铁(集团)公司 | Structural steel with yield strength of 500 MPa for bridges and production method of structural steel |
| CN105695863A (en) * | 2016-02-04 | 2016-06-22 | 首钢总公司 | Hot-rolled coiled plate for natural gas delivery pipeline and manufacturing method thereof |
| CN108754335A (en) * | 2018-08-22 | 2018-11-06 | 武汉钢铁有限公司 | A kind of the welding structure fire-resistant and weather-resistant steel and production method of yield strength >=550MPa |
| CN108796370A (en) * | 2018-06-13 | 2018-11-13 | 武汉钢铁有限公司 | A kind of the welding structure fire-resistant and weather-resistant steel and its production method of yield strength >=690MPa |
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| CN114807761A (en) * | 2022-04-28 | 2022-07-29 | 鞍钢股份有限公司 | EH36 grade ocean engineering steel with high ductility and manufacturing method thereof |
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| CN105063509A (en) * | 2015-07-27 | 2015-11-18 | 武汉钢铁(集团)公司 | Structural steel with yield strength of 500 MPa for bridges and production method of structural steel |
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| CN108796370A (en) * | 2018-06-13 | 2018-11-13 | 武汉钢铁有限公司 | A kind of the welding structure fire-resistant and weather-resistant steel and its production method of yield strength >=690MPa |
| CN108754335A (en) * | 2018-08-22 | 2018-11-06 | 武汉钢铁有限公司 | A kind of the welding structure fire-resistant and weather-resistant steel and production method of yield strength >=550MPa |
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| CN110306114B (en) * | 2019-07-26 | 2020-10-30 | 武汉钢铁有限公司 | Corrosion-resistant and fire-resistant structural steel with yield strength of 460MPa and production method thereof |
| CN110306114A (en) * | 2019-07-26 | 2019-10-08 | 武汉钢铁有限公司 | A kind of yield strength is 460MPa grades of anti-corrosion fireproof construction steel and production method |
| CN112934959A (en) * | 2021-01-30 | 2021-06-11 | 武安市裕华钢铁有限公司 | Rolling process for optimizing yield strength of cold-rolled substrate |
| CN112934959B (en) * | 2021-01-30 | 2023-03-10 | 武安市裕华钢铁有限公司 | Rolling process for optimizing yield strength of cold-rolled substrate |
| CN114807761A (en) * | 2022-04-28 | 2022-07-29 | 鞍钢股份有限公司 | EH36 grade ocean engineering steel with high ductility and manufacturing method thereof |
| CN114807761B (en) * | 2022-04-28 | 2023-08-18 | 鞍钢股份有限公司 | EH36 grade marine engineering steel having high ductility and method for manufacturing same |
| CN115466905A (en) * | 2022-08-31 | 2022-12-13 | 马鞍山钢铁股份有限公司 | Non-quenched and tempered steel with good corrosion resistance for 10.9-grade large-size wind power bolt and production method thereof |
| CN115466905B (en) * | 2022-08-31 | 2023-07-25 | 马鞍山钢铁股份有限公司 | Non-quenched and tempered steel with good corrosion resistance for 10.9-grade large-specification wind power bolts and production method thereof |
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