CN102433507B - Low yield ratio and high strength weldable steel plate and preparation technology thereof - Google Patents
Low yield ratio and high strength weldable steel plate and preparation technology thereof Download PDFInfo
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Abstract
The invention discloses a low yield ratio and high strength weldable steel plate and a preparation technology thereof. The steel plate comprises the following chemical compositions by weight percent: 0.07-0.09% of C, 0.20-0.35% of Si, 1.30-1.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.010% of S, 0.25-0.45% of Cr, 0.02-0.035% of Nb, 0.0005-0.0020% of B and the balance of Fe and inevitable impurities. The alloying components are designed reasonably, controlled rolling and controlled cooling technologies are adopted, the thickness of the prepared steel plate finished product is no less than 15mm, the structure contains ferrite and bainite, the yield strength is 460-560MPa, the tensile strength is 700-790MPa, the elongation after fracture is no less than 14% and the yield ratio is less than 0.7. The low yield ratio and high strength weldable steel plate has simple production technology and good welding performance, cold bending property and plate profile, and can be widely used in fields such as bridges, building structures and engineering machinery.
Description
Technical field
The present invention relates to a kind of High Strength Steel Plate, particularly the easy welding high-strength steel plate of a kind of low yield strength ratio and preparation technology thereof.
Background technology
High-strength steel is one of important structural timber, is widely used in the fields such as shipbuilding, bridge structure, building structure, transportation by railroad, machinofacture.Along with society and expanding economy, Iron And Steel Industry is faced with the problems such as resource price is surging, the demand speedup eases up, environmental stress increase.Therefore, reduce the alloy addition level of steel, reduce production process, shorten the production cycle, raise the efficiency, develop there is low cost, good comprehensive mechanical performance and the ferrous materials of use properties, become the important directions of ferrous materials research, require steel to there is good obdurability, weldability and security and stability.
The manufacture patent of at present existing many low yield strength ratio High Strength Steel Plates, as CN101619423A, CN101775552A, CN101497972A, CN101660108A, CN101660099A, CN101775561A, CN101985725A, CN101649420A etc., from one-tenth, assign to, alloying element adds more, what adopt is Ni, Mo, Cu composition system, has mostly added precious metal as Ni, Mo etc., has increased the production cost of steel, the Pcm value of steel plate is also higher simultaneously, causes welding property not good.
Although the technology contents that patent CN101857942A, CN101880825A, CN101792882A, CN102212743A etc. relate to does not adopt Ni, Mo composition system, use controlled rolling and Controlled cooling process, but the product of its production is the roll bending of thickness≤10mm, be not suitable for the manufacture of thicker product.
From production technology characteristic, the research and production of current low yield strength ratio high-strength steel, the overwhelming majority is all to adopt controlled rolling+off-line heat-treating methods, to obtain the high-intensity performance requriements of low yield strength ratio, the technology contents related to as patents such as CN1786246A, CN101328564A, CN101260495A, CN101613828A, CN102011068A adopts the thermal treatment process such as intercritical hardening, intercritical hardening+tempering.Although yield tensile ratio that can the decrease steel plate with aforesaid method, used heat treatment step to make the production cycle longer, cost increases, and production efficiency is lower.
Summary of the invention
The object of the invention is to propose the easy welding high-strength steel plate of a kind of low yield strength ratio and preparation technology thereof.By reasonable interpolation alloying element, welding crack sensibility indices P cm≤0.2%, adopt controlled rolling+Controlled cooling process, make its steel plate be organized as ferrite+bainite, yield strength Rp0.2 is 460～560MPa, and tensile strength Rm is 700～790MPa, elongation after fracture >=14%, yield tensile ratio (Rp0.2/Rm)<0.7 ,-20 ℃ of ballistic work>80J.
For achieving the above object, the present invention adopts following technical scheme:
The easy welding high-strength steel plate of a kind of low yield strength ratio, its chemical composition is by weight percentage: C 0.07～0.09%, Si 0.20～0.35%, and Mn 1.30～1.50%, P≤0.025%, S≤0.010%, Cr 0.25～0.45%, Nb0.02～0.035%, and B 0.0005～0.0020%, all the other are Fe and inevitable impurity, and meet following welding crack sensibility index:
Pcm＝C+Si/30+Mn/20+Cu/20+Cr/20+Mo/15+Ni/60+V/10+5B≤0.20％。
Below to the selection concrete analysis explanation of the effect of contained component in the easy welding high-strength steel plate of low yield strength ratio of the present invention and consumption thereof:
C:C plays an important role to intensity, low-temperature flexibility, the welding property of material.The content of carbon is controlled too low (generally lower than 0.025%), can not proof strength, and during too high levels (generally higher than 0.10%), the more difficult control of welding property and low-temperature flexibility.In the present invention, carbon content is chosen in 0.07～0.09%, can guarantee bainite content certain in steel, guarantees certain intensity, toughness and good weldability.
Si:Si can enlarge α-γ district, and the temperature that makes critical zone process is widened.Silicon is the bioelement of deoxidation in steel making simultaneously, can increase the intensity of material, but low-temperature flexibility and the welding property of infringement material, so the content of silicon is controlled at 0.20～0.35%.
The Mn:Mn element is typical austenite stabilizer element, can improve the hardening capacity of steel, and play solution strengthening effect, under the low-carbon (LC) condition, the intensity that improves material is had to significant effect, therefore, when the higher steel of production intensity, the content of Mn should not be too low, and the relative low price of Mn, but excessive Mn makes the more difficult control of casting process, the easy and elements such as P, S form segregations, the impact property of severe exacerbation material and welding property.Therefore the content of Mn is controlled at 1.30～1.50%.
Cr:Cr can significantly improve the hardening capacity of steel, postpones perlitic transformation, promotes that C spreads to austenite simultaneously, and reduces ferritic yield strength, is conducive to obtain the dual phase steel of low yield strength ratio.Therefore the content of Cr is controlled at 0.25～0.45%.
Nb:Nb is the important element in rolling controlled and cooling controlled steel, can stop the adding of Nb the recrystallize after austenite deformation, improves austenite recrystallization temperature.Nb can significantly suppress ferritic transformation, and along with the increase of cooling rate, the restraining effect of Nb strengthens, the ferrite grain size refinement.Therefore the content of Nb is controlled at 0.02～0.035%.
B:B can improve the hardening capacity of steel plate, but excessive B easily causes Grain Boundary Segregation, impelling strength and the weldability of infringement steel plate.The content of B is controlled at 0.0005～0.002%.
P, S:P, S be as harmful being mingled with in steel, and low-temperature impact and the weldability of steel had to larger detrimental effect, and it is more low better to require in theory, but considers steel-making operability and steel-making cost, controls P≤0.025%, S≤0.010%.
The preparation technology of the easy welding high-strength steel plate of a kind of low yield strength ratio, it comprises the steps:
(1) smelt, be cast into slab according to above-mentioned chemical component weight per-cent;
(2), to above-mentioned heating of plate blank, Heating temperature is 1180～1220 ℃, soaking time 1.5～2.5h;
(3) controlled rolling, roughing start rolling temperature≤1000 ℃, roughing finishing temperature >=970 ℃, pass deformation rate is 10～30%; 870～850 ℃ of finish rolling start rolling temperatures, the finish rolling finishing temperature is 790～840 ℃, pass deformation rate is 10～30%, overall compression ratio >=5;
(4) control coolingly, adopt water cooling system, opening cold temperature is 780～830 ℃, cooling rate >=15 ℃/s, eventually cold≤400 ℃, air cooling is to room temperature afterwards.
Compared with prior art, the present invention has but not only has the following advantages:
(1), containing expensive metal elements such as Ni, Mo, simultaneously, production technique is not without follow-up thermal treatment for designing chemical composition, and production cost is low.
(2) production technique adopts controlled rolling+Controlled cooling process, and without follow-up thermal treatment, production technique is simple, and the cycle is short, and efficiency is high.
(3) by above-mentioned design mix and rolling technology, the steel plate that can make is organized as ferrite+bainite, and yield strength Rp0.2 is 460～560MPa, tensile strength Rm is 700～790MPa, elongation after fracture >=14%, yield tensile ratio (Rp0.2/Rm)<0.7 ,-20 ℃ of ballistic work>80J.
(4) by above-mentioned designing chemical composition, its welding crack sensibility indices P cm≤0.20%, Plate Welding excellent property.
The accompanying drawing explanation
The microstructure picture that Fig. 1 is embodiment 1 light plate vertical section;
The microstructure picture that Fig. 2 is embodiment 2 light plate vertical sections;
The microstructure picture that Fig. 3 is embodiment 3 light plate vertical sections;
The microstructure picture that Fig. 4 is embodiment 4 light plate vertical sections.
Embodiment
Below in conjunction with accompanying drawing and some preferred embodiments, technical scheme of the present invention is described in further detail, but is not limited to this.
Embodiment 1
This steel (wt%) composed of the following components: C:0.075%, Si:0.28%, Mn:1.33%, P:0.0077%, S:0.0053%, Cr:0.31%, Nb:0.028%, B:0.0009%, all the other are Fe and inevitable impurity, the welding crack sensibility index:
Pcm＝C+Si/30+Mn/20+Cu/20+Cr/20+Mo/15+Ni/60+V/10+5B＝0.17％。
The mechanical property of steel plate is in Table 1, and its production technique comprises the steps:
(1) smelt, be cast into slab according to above-mentioned chemical component weight per-cent;
(2), to above-mentioned heating of plate blank, Heating temperature is 1180～1220 ℃, soaking time 2h;
(3) controlled rolling, roughing start rolling temperature≤1000 ℃, roughing finishing temperature >=970 ℃, pass deformation rate is 10～30%; 850～870 ℃ of finish rolling start rolling temperatures, the finish rolling finishing temperature is 790～840 ℃, pass deformation rate is 10～30%, overall compression ratio >=5, the thick 20mm of finished product;
(4) control coolingly, adopt the laminar flow water cooling system, opening cold temperature is 780～830 ℃, and cooling rate is 15～25 ℃/s, and cold eventually is 200～400 ℃, and air cooling is to room temperature afterwards.
Embodiment 2
This steel C:0.075% composed of the following components, Si:0.28%, Mn:1.33%, P:0.0077%, S:0.0053%, Cr:0.31%, Nb:0.028%, B:0.0009%, all the other are Fe and inevitable impurity, the welding crack sensibility index:
Pcm＝C+Si/30+Mn/20+Cu/20+Cr/20+Mo/15+Ni/60+V/10+5B＝0.17％。
The mechanical property of steel plate is in Table 1, and its production technique comprises the steps:
(1) smelt, be cast into slab according to above-mentioned chemical component weight per-cent;
(2), to above-mentioned heating of plate blank, Heating temperature is 1180～1220 ℃, soaking time 2h;
(3) controlled rolling, roughing start rolling temperature≤1000 ℃, roughing finishing temperature >=970 ℃, pass deformation rate is 10～30%; 850～870 ℃ of finish rolling start rolling temperatures, the finish rolling finishing temperature is 790～840 ℃, pass deformation rate is 10～30%, overall compression ratio >=5, the thick 20mm of finished product;
(4) control coolingly, adopt the laminar flow water cooling system, opening cold temperature is 780～830 ℃, cooling rate >=25 ℃/s, eventually cold≤200 ℃, air cooling is to room temperature afterwards.
Embodiment 3
This steel (wt%) composed of the following components: C:0.09%, Si:0.3%, Mn:1.50%, P:0.0089%, S:0.0079%, Cr:0.40%, Nb:0.03%, B:0.0008%, all the other are Fe and inevitable impurity, the welding crack sensibility index:
Pcm＝C+Si/30+Mn/20+Cu/20+Cr/20+Mo/15+Ni/60+V/10+5B＝0.20％。
The mechanical property of steel plate is in Table 1, and its production technique comprises the steps:
(1) smelt, be cast into slab according to above-mentioned chemical component weight per-cent.
(2), to above-mentioned heating of plate blank, Heating temperature is 1180～1220 ℃, soaking time 2h;
(3) controlled rolling, roughing start rolling temperature≤1000 ℃, roughing finishing temperature >=970 ℃, pass deformation rate is 10～30%; 850～870 ℃ of finish rolling start rolling temperatures, the finish rolling finishing temperature is 790～840 ℃, pass deformation rate is 10～30%, overall compression ratio >=5, the thick 20mm of finished product;
(4) control coolingly, adopt the laminar flow water cooling system, opening cold temperature is 780～830 ℃, cooling rate >=25 ℃/s, eventually cold≤200 ℃, air cooling is to room temperature afterwards.
Embodiment 4
This steel (wt%) composed of the following components: C:0.09%, Si:0.3%, Mn:1.50%, P:0.0089%, S:0.0079%, Cr:0.40%, Nb:0.03%, B:0.0008%, all the other are Fe and inevitable impurity, the welding crack sensibility index:
Pcm＝C+Si/30+Mn/20+Cu/20+Cr/20+Mo/15+Ni/60+V/10+5B＝0.20％。
The mechanical property of steel plate is in Table 1, and its production technique comprises the steps:
(1) smelt, be cast into slab according to above-mentioned chemical component weight per-cent.
(2), to above-mentioned heating of plate blank, Heating temperature is 1180～1220 ℃, soaking time 2h;
(3) controlled rolling, roughing start rolling temperature≤1000 ℃, roughing finishing temperature >=970 ℃, pass deformation rate is 10～30%; 850～870 ℃ of finish rolling start rolling temperatures, the finish rolling finishing temperature is 790～840 ℃, pass deformation rate is 10～30%, overall compression ratio >=5, the thick 30mm of finished product;
(4) control coolingly, adopt the laminar flow water cooling system, opening cold temperature is 780～830 ℃, cooling rate >=25 ℃/s, eventually cold≤200 ℃, air cooling is to room temperature afterwards.
Low yield strength ratio high-strength steel mechanical property in table 1 embodiment of the present invention 1-4
| Thickness of slab | Rp0.2/MPa | Rm/Mpa | A/％ | Yield tensile ratio | -20 ℃ of vertical Akv/J | |
| Embodiment 1 | 20mm | 456 | 707 | 24 | 0.645 | 238，230，221 |
| Embodiment 2 | 20mm | 487 | 719 | 23 | 0.677 | 202，209，171 |
| Embodiment 3 | 20mm | 546 | 785 | 14 | 0.696 | 89，94，82 |
| Embodiment 4 | 30mm | 527 | 762 | 18 | 0.692 | 94，119，82 |
Annotate: tension specimen adopts the bar-shaped sample that gauge length is φ 8 * 40mm; Charpy bar is of a size of 10 * 10 * 55mm, and test temperature is-20 ℃.
Claims (1)
1. the easy welding high-strength steel plate of low yield strength ratio, it is characterized in that described steel plate chemical constitution is by weight percentage: C0.07～0.09%, Si0.20～0.35%, Mn1.30～1.50%, P≤0.025%, S≤0.010%, Cr0.25～0.31%, Nb0.02～0.028%, B0.0005～0.0020%, all the other are Fe and inevitable impurity; The welding crack sensibility index of this steel plate
Pcm＝C+Si/30+Mn/20+Cu/20+Cr/20+Mo/15+Ni/60+V/10+5B≤0.20％;
According to following technique, prepared by this steel plate:
(1) in smelting, casting operation, according to above-mentioned chemical component weight per-cent, smelt, be cast into slab;
(2), in heating process, slab heating temperature is 1180～1220 ℃, is incubated 1.5～2.5h;
(3) in rolling process, roughing start rolling temperature≤1000 ℃, roughing finishing temperature >=970 ℃, pass deformation rate is 10～30%; 850～870 ℃ of finish rolling start rolling temperatures, the finish rolling finishing temperature is 790～840 ℃, pass deformation rate is 10～30%, overall compression ratio >=5;
(4) in refrigerating work procedure, adopt water cooling system, opening cold temperature is 780～830 ℃, cooling rate >=25 ℃/s, final cooling temperature≤400 ℃, air cooling is to room temperature afterwards;
The finished product thickness of described steel plate is 20mm, and this steel plate yield strength is 460～560MPa, and tensile strength is 700～790MPa, elongation after fracture >=14%, yield tensile ratio<0.7 ,-20 ℃ of ballistic work>80J.
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| CN110669914B (en) * | 2019-09-30 | 2021-07-06 | 鞍钢股份有限公司 | High-strength steel for automobile axle housing for cold stamping and production method thereof |
| CN112210649B (en) * | 2020-09-25 | 2022-06-28 | 邯郸钢铁集团有限责任公司 | Flexible control method for yield ratio of high-strength steel |
| CN112501496B (en) * | 2020-10-20 | 2022-01-04 | 江苏省沙钢钢铁研究院有限公司 | On-line quenching type double-phase low-yield-ratio steel plate and production method thereof |
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| CN101792882A (en) * | 2010-01-08 | 2010-08-04 | 唐山国丰钢铁有限公司 | Production method of boracic hot-rolled coil plates with low yield ratio |
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| US5667605A (en) * | 1994-12-13 | 1997-09-16 | Ascometal | Method of fabrication of a piece of structural steel, and the steel fabricated thereby |
| CN101619423A (en) * | 2008-06-30 | 2010-01-06 | 鞍钢股份有限公司 | Steel plate for high-strength high-toughness low-yield easily-welding structure and method for manufacturing same |
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