CN102644024A - Low-alloy low-yield-ratio steel for oceaneering structure and production method thereof - Google Patents
Low-alloy low-yield-ratio steel for oceaneering structure and production method thereof Download PDFInfo
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Abstract
Provided are a low-alloy low-yield-ratio steel for an oceaneering structure and a production method thereof. The steel contains the following chemical components by mass: 0.09-0.13% of C, 0.15-0.40% of Si, 0.80-1.50% of Mn, 0.01-0.04% of Alt, 0.02-0.04% of Nb, 0.008-0.018% of Ti, less than 0.015% of P, less than 0.005% of S and the balance, Fe and unavoidable impurities. The production method includes that thick plate slabs of 250-400mm are heated before being rolled with heating temperature as 1180-1260 DEG C, rolling is divided into two stages, start rolling temperature at an austenite recrystallization area is 1000-1100 DEG C, start rolling temperature at an austenite non-recrystallization area is 850-950 DEG C, finishing rolling temperature is 790-820 DEG C, the thick plate slabs enter a water cooling area after being rolled with cooling speed as 9-12 DEG C/s and fishing cooling temperature as 450-500 DEG C, and steel plates are cooled in heap for more than 12 hours after being taped out. The steel has the advantages of good strength, low yield ratio, good toughness and good lamellar tearing resistant performance, thereby being capable of being used in oceaneering structure construction under severe conditions.
Description
Technical field
The invention belongs to oceanographic engineering worker technical field, particularly relate to a kind of low-alloy low yield strength ratio offshore engineering structure with steel and working method thereof.
Background technology
Offshore engineering structure is the important ultra-large type welded steel structure of ocean platform; Be applied in the severe ocean Working environment such as wave, tide, storm and cold floating ice; Support platform and drilling outfit that gross weight surpasses hundreds of tons, stand the test of abominable natural disaster such as earthquake, tsunami simultaneously again.These use characteristic have determined offshore engineering structure must have performances such as HS, H.T., low yield strength ratio and anti-lamellar tearing with steel.
Yet because the character of said steel, the low-temperature flexibility of steel plate can reduce along with the increase of armor plate strength usually.The increase of armor plate strength simultaneously also can cause the increase of yield tensile ratio.The offshore engineering structure of producing at present generally adopts with steel and adds a large amount of alloying elements, takes to roll back tempering or modifier treatment on the technology, has not only increased production cost but also can not guarantee the performance of steel plate low yield strength ratio.
Publication number is 460MPa level super-thick steel plate for low yield ratio buildings and method of manufacture for the CN101613828A patent of invention proposes a kind of ys; It need add the V alloy element; The adding of V element has disadvantageous effect to welding property, and adopts hardening and tempering process, and production cost is high; Complex procedures, the production cycle is long.The observed value that does not relate to the ballistic work below-20 ℃.
Publication number proposes steel for controlled rolling and controlled cooling platform and working method thereof for the CN101358320A patent of invention, need to add V and be higher than 0.03% Nb, but its tensile strength is lower than 610MPa, does not relate to yield tensile ratio and steel plate heart portion low-temperature impact work observed value.
Publication number is used steel for the CN101906591A patent of invention adopts controlled rolling and controlled cooling+tempering process to produce 460MPa level offshore engineering structure; But it needs subsequent heat treatment; Alloying elements such as Ni, Cr, Cu, Mo have been added; When increasing cost, welding property is had disadvantageous effect, heart portion low-temperature flexibility is not set forth, yield tensile ratio is high.
Publication number proposes a kind of the have HS of good low-temperature flexibility and the working method of low yield strength ratio structural steel for the CN101868560A patent of invention; It need add valuable alloying elements such as Cr, Mo, Ni, Cu, V; Its complex manufacturing control window narrows is unfavorable for industrialized production, does not relate to heart portion low-temperature flexibility and anti-lamellar tearing Research on ability and description.
Publication number proposes the excellent working method that contains the niobium steel of a kind of ultralow-temperature flexibility for the CN101255528A patent of invention; Its C content is extremely low, and the control difficulty is big during smelting, and Nb content is 0.04-0.10%; Content is higher; Its tensile strength can not be stablized and reaches 610MPa, and steel plate thickness does not relate to the description to steel plate heart portion low-temperature impact toughness at 20-30mm.
Do not have at present temporarily and adopt low-alloy to produce low yield strength ratio, HS, H.T. offshore engineering structure precedent with steel.
Summary of the invention
The object of the present invention is to provide a kind of low-alloy low yield strength ratio offshore engineering structure with steel and working method thereof; Low-alloy composition (only adding Nb, the Ti alloy of trace); Rationally and be convenient to rolling, the water-cooled of suitability for industrialized production, produce the offshore engineering structure of low yield strength ratio, HS, H.T. and use steel.
A kind of low-alloy low yield strength ratio offshore engineering structure provided by the invention uses the chemical ingredients of steel by mass percent to be: C 0.09-0.13%, Si 0.15-0.40%, Mn 0.80-1.50%; Alt 0.01-0.04%; Nb 0.02-0.04%, Ti 0.008-0.018%, P≤0.010%; S≤0.005%, its amount is Fe and inevitable impurity.
C content of the present invention is controlled at 0.09-0.13%, because C is one of the most cheap strengthening element, for guaranteeing the intensity of steel plate, is limited to 0.09% under the C content.But will produce adverse influence to steel plate toughness and welding property during the C too high levels, thus C content on be limited to 0.13%.
Si content of the present invention is controlled at 0.15-0.40%, in steelmaking process, adds Si as reductive agent and reductor, so killed steel contains the silicon of 0.15-0.40%, and Si can improve the intensity of steel plate through the solution strengthening mode.But the Si too high levels has disadvantageous effect to toughness and welding property, thereby the upper limit must be set.
Mn content of the present invention is controlled at 0.80-1.50%, and in steelmaking process, Mn is good reductor and sweetening agent, and Mn also is the principal element that improves hardness of steel.But it is all unfavorable during the Mn too high levels to toughness and welding property.
Nb content of the present invention is controlled at 0.02-0.04%, adds an amount of Nb in the steel, and purpose is to be convenient to carry out the non-recrystallization controlled rolling.Nb also can stop growing up of austenite crystal, crystal grain thinning.Niobium is a kind of strong carbide forming element in addition, the NbC that in steel, forms, Nb (CN) grade in an imperial examination two-phase particle, the intensity and the low-temperature flexibility of raising steel.Add a large amount of Nb and not only do not have better reinforcement and thin brilliant effect, be prone on the contrary produce intergranular crack, the upper limit is set to 0.04%.
Ti content of the present invention is controlled at 0.008-0.018%; Titanium is a kind of intensive carbide and nitride forming element; The carbonitride that does not dissolve of Ti can stop growing up of austenite crystal when steel heats; The TiN that when the high temperature austenite roughing, separates out, TiC can effectively suppress grain growth, improve the solid solubility of Nb in austenite simultaneously.When welding, the TiN in the steel, TiC particle can significantly stop the heat affected zone grain growth, thereby improve welding property.But the Ti too high levels then generates the TiC carbide, and low-temperature flexibility is reduced.
Al content of the present invention is controlled at 0.01-0.04%, and Al is the main deoxidant element in the steel, helps crystal grain thinning, all adds a certain amount of Al in the general steel.
P and S are inevitable harmful element in the steel, and be unfavorable to the plasticity and the toughness of steel, should reduce P and S content as far as possible, improves the cleanliness factor of steel.But consider and reduce P, of difficulty and the cost increase of S content, P control≤0.010% in the steel of the present invention, S control≤0.005% smelting.
The working method that the present invention relates to comprises that desulfurizing iron skims → 100t converter smelting → ladle deoxidation alloying → LF stove refining → RH vacuum-treat → conventional slab caster cast → slab heating → controlled rolling → controlled chilling → steel plate cooling in heap that rolls off the production line.It is characterized in that: adopt carbon containing 0.09～0.13% carbon steel smelting process for production; Add micro-Nb, Ti alloy; Carry out vacuum-treat behind the ladle furnace refining; The permanent pulling rate of slab with gently depress technology, the assurance slab quality; On wide and heavy plate mill, carry out the controlled rolling of two stages; Roll back controlled chilling system, final cooling temperature 450-500 ℃, 9～12 ℃/S of speed of cooling.Plate property: ys>=460MPa, tensile strength>=610MPa, yield tensile ratio≤0.80, unit elongation>=20%, the Charpy-V impact power average>=100J of heart portion-60 ℃, Z surpasses 35% to relative reduction in area.
Technical scheme of the present invention may further comprise the steps:
(1) smelting system: according to C 0.09-0.13%, Si 0.15-0.40%, Mn 0.80-1.50%, Alt 0.01-0.04%, Nb 0.02-0.04%, Ti 0.008-0.018%, P≤0.010%, S≤0.005%, the low-alloy composition smelt;
(2) continuous casting is the 250-400mm heavy slab behind (2) converter smelting, carries out reheat before rolling, and Heating temperature is 1180-1260 ℃;
(3)) controlled rolling and controlled cooling; In two stages rolling, promptly the recrystallization zone is rolling rolling with the non-recrystallization district, and start rolling temperature is 1000～1100 ℃ in the austenite recrystallization district; 850～950 ℃ of austenite non-recrystallization district start rolling temperatures, 790～820 ℃ of finishing temperatures, steel plate rolls the back and gets into the rapid cooling zone territory rapidly, and cold but temperature is 450～500 ℃ eventually, 9～12 ℃/s of speed of cooling;
(5) cooling in heap system: the steel plate laggard windrow that rolls off the production line is cold, and cooling in heap begins temperature 350-450 ℃, and the cooling in heap time is no less than 12 hours.
Preferably, step (3) is at austenite recrystallization single pass minimal deformation rate >=8%, and deformation rate >=20% passage is not less than 2 passages, accumulative total deformation rate >=60%.
The invention has the advantages that:
(1) alloy designs is simple, and cost is low: only add little amount of N b, Ti microalloy, do not add alloying elements such as V, Ni.
(2) reasonable technology system: through the Clean Steel technology, reduce P, S content, control inclusion and center segregation guarantee the strand internal soundness, for steel plate heart portion impelling strength provides good guarantee; Guarantee big draught and the big cooling rate of water cooling stage of controlled rolling stage, the performance of intensity, center toughness and low yield strength ratio through controlled rolling and controlled cooling institutional guarantee steel plate.
(the high comprehensive performance of 3 steel of the present invention; Ys can be stablized and reaches>=460MPa; Tensile strength>=610MPa, yield tensile ratio≤0.80, the heart portion-60 equal value stabilization of ℃ low-temperature impact work reaches>=100J; Z to relative reduction in area greater than 35%, can satisfy offshore engineering structure with steel to intensity, heart portion low-temperature flexibility, low yield strength ratio and anti-lamellar tearing performance requriements.Good intensity, low yield strength ratio, toughness and anti-lamellar tearing performance; Can be used for mal-condition Offshore Platform Structures Subjected engineering structure builds.Opened up a kind of low-alloy and produced the method for high-intensity high-tenacity low yield strength ratio offshore engineering structure with steel.
Description of drawings
Fig. 1 is the reduction schedule of 40mm Plate Steel.
Fig. 2 is the surperficial microstructure in 40mm Plate Steel transverse section.
Fig. 3 is the heart portion microstructure in 40mm Plate Steel transverse section.
Concrete embodiment
Hereinafter will be described in detail exemplary of the present invention.The explanation that it should be understood that among this paper to be proposed just only is used to illustrate the embodiment of purpose, is not intended to limit scope of the present invention.
Table 1 composition weight/%
| Numbering | C | Si | Mn | P | S | Alt | Nb | Ti |
| A | 0.11 | 0.34 | 1.37 | 0.012 | 0.0018 | 0.034 | 0.028 | 0.012 |
| B | 0.13 | 0.35 | 1.40 | 0.011 | 0.0013 | 0.036 | 0.028 | 0.013 |
| C | 0.10 | 0.37 | 1.39 | 0.012 | 0.0015 | 0.032 | 0.029 | 0.013 |
| D | 0.09 | 0.34 | 1.38 | 0.011 | 0.0017 | 0.031 | 0.028 | 0.013 |
Be rolled with the listed condition of table 2 and cool off with the thick steel billet of 250mm of listed composition of table 1 and content preparation thereof.
Table 2 technology
Table 3 performance
Claims (3)
1. a low-alloy low yield strength ratio offshore engineering structure is used steel, and it is characterized in that: the chemical ingredients of this steel is by mass percentage: C 0.09-0.13%, Si 0.15-0.40%; Mn 0.80-1.50%, Alt 0.01-0.04%, Nb 0.02-0.04%; Ti 0.008-0.018%; P≤0.015%, S≤0.005%, surplus is Fe and inevitable impurity.The performance of this steel is: ys>=460MPa, and tensile strength>=610MPa, yield tensile ratio≤0.80, unit elongation>=20%, the Charpy-V impact power average>=100J of heart portion-60 ℃, Z surpasses 35% to relative reduction in area.
2. the described low-alloy low yield strength ratio of claim 1 offshore engineering structure is with the preparation method of steel, comprises that desulfurizing iron skims → 100t converter smelting → ladle deoxidation alloying → LF stove refining → RH vacuum-treat → conventional slab caster cast → slab heating → controlled rolling → controlled chilling → steel plate cooling in heap that rolls off the production line; Its characteristic also is: the technical parameter of in technology, controlling is:
(1) smelt: according to C 0.09-0.13%, Si 0.15-0.40%, Mn 0.80-1.50%, Alt 0.01-0.04%, Nb 0.02-0.04%, Ti 0.008-0.018%, P≤0.010%, S≤0.005%, the low-alloy composition smelt;
(2) continuous casting is the 250-400mm heavy slab behind the converter smelting, carries out reheat before rolling, and Heating temperature is 1180-1260 ℃;
(3) controlled rolling and controlled cooling; In two stages rolling, promptly the recrystallization zone is rolling rolling with the non-recrystallization district, and start rolling temperature is 1000～1100 ℃ in the austenite recrystallization district; 850～950 ℃ of austenite non-recrystallization district start rolling temperatures, 790～820 ℃ of finishing temperatures, steel plate rolls the back and gets into the rapid cooling zone territory rapidly, and cold but temperature is 450～500 ℃ eventually, 9～12 ℃/s of speed of cooling.
(4) cooling in heap: cooling in heap begins temperature 350-450 ℃, and the cooling in heap time is no less than 12 hours.
3. method according to claim 2 is characterized in that, step (3) is at austenite recrystallization single pass minimal deformation rate >=8%, and deformation rate >=20% passage is not less than 2 passages, accumulative total deformation rate >=60%.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103451534A (en) * | 2013-09-18 | 2013-12-18 | 济钢集团有限公司 | 60mm steel plate with excellent performance in thickness direction for ocean platform and production method thereof |
| CN103469106A (en) * | 2013-09-17 | 2013-12-25 | 江阴兴澄特种钢铁有限公司 | Large-thickness rack steel plate directly produced by continuous casting billet and manufacturing method of large-thickness rack steel plate |
| CN103667909A (en) * | 2013-12-13 | 2014-03-26 | 武汉钢铁(集团)公司 | Mobile ocean platform steel with yield ratio not greater than 0.65 and production method thereof |
| CN111455272A (en) * | 2020-03-25 | 2020-07-28 | 南京钢铁股份有限公司 | Hot-rolled high-strength S500M L steel plate and production method thereof |
| CN112795842A (en) * | 2020-12-25 | 2021-05-14 | 鞍钢股份有限公司 | Steel for submarine quick connection pipeline and production method thereof |
| CN114807766A (en) * | 2022-05-05 | 2022-07-29 | 重庆钢铁股份有限公司 | Microalloy steel plate for low-temperature pressure vessel and production method thereof |
| CN115558863A (en) * | 2022-10-19 | 2023-01-03 | 鞍钢集团北京研究院有限公司 | Marine steel with yield strength of more than or equal to 750MPa and low yield ratio and production process thereof |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103469106A (en) * | 2013-09-17 | 2013-12-25 | 江阴兴澄特种钢铁有限公司 | Large-thickness rack steel plate directly produced by continuous casting billet and manufacturing method of large-thickness rack steel plate |
| CN103469106B (en) * | 2013-09-17 | 2016-08-17 | 江阴兴澄特种钢铁有限公司 | Directly produce big thickness rack steel plate and manufacture method thereof with continuous casting billet |
| CN103451534A (en) * | 2013-09-18 | 2013-12-18 | 济钢集团有限公司 | 60mm steel plate with excellent performance in thickness direction for ocean platform and production method thereof |
| CN103667909A (en) * | 2013-12-13 | 2014-03-26 | 武汉钢铁(集团)公司 | Mobile ocean platform steel with yield ratio not greater than 0.65 and production method thereof |
| CN103667909B (en) * | 2013-12-13 | 2016-02-03 | 武汉钢铁(集团)公司 | A kind of mobile ocean Platform Steel of yield tensile ratio≤0.65 and production method |
| CN111455272A (en) * | 2020-03-25 | 2020-07-28 | 南京钢铁股份有限公司 | Hot-rolled high-strength S500M L steel plate and production method thereof |
| CN112795842A (en) * | 2020-12-25 | 2021-05-14 | 鞍钢股份有限公司 | Steel for submarine quick connection pipeline and production method thereof |
| CN112795842B (en) * | 2020-12-25 | 2022-05-13 | 鞍钢股份有限公司 | Steel for submarine quick connection pipeline and production method thereof |
| CN114807766A (en) * | 2022-05-05 | 2022-07-29 | 重庆钢铁股份有限公司 | Microalloy steel plate for low-temperature pressure vessel and production method thereof |
| CN115558863A (en) * | 2022-10-19 | 2023-01-03 | 鞍钢集团北京研究院有限公司 | Marine steel with yield strength of more than or equal to 750MPa and low yield ratio and production process thereof |
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Address after: 100041 Shijingshan Road, Shijingshan District, Shijingshan District, Beijing Patentee after: Shougang Group Co. Ltd. Address before: 100041 Shijingshan Road, Shijingshan District, Shijingshan District, Beijing Patentee before: Capital Iron & Steel General Company |