CN103194671A - Nb-V composite microalloyed low-carbon high-strength low-alloy steel for ships - Google Patents
Nb-V composite microalloyed low-carbon high-strength low-alloy steel for ships Download PDFInfo
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Abstract
The invention discloses an Nb-V composite microalloyed low-carbon high-strength low-alloy steel for ships. The steel comprises the components of carbon, silicon, manganese, vanadium, niobium, phosphorus, sulfur, aluminum and iron, wherein the weight percent contents of carbon, vanadium and niobium are as follows: C: 0.10-0.15%, V: 0.06-0.09%, and Nb: 0.23-0.32%. The preparation method of the steel comprises the following steps of: smelting iron in a blast furnace, pretreating molten steel so as to remove sulfur, smelting in a converter so as to remove carbon, increasing the temperature and removing oxygen from the molten steel, subsequently adding niobium and vanadium so as to microalloy the molten steel, carrying out argon blowing refining and aluminum wire deoxygenation, and carrying out slab continuous casting. The steel is applied to rolling middle-thickness plates for ships. The steel has the advantages that the steel for ships is high in strength, good in low-temperature toughness, low in carbon equivalent weight after being prepared, and good in properties in welding, machining, shaping and the like; and the prepared high-strength middle-thickness plates for the ships are good in corrosion resistance and fatigue resistance, and are applicable to the fields of large-sized vessels, offshore petroleum drilling platforms and the like, and the tensile strength of the prepared high-strength middle-thickness plates is greater than 530+/-20MPa.
Description
Technical field
The present invention relates to the high-strength ship plates technical field, particularly a kind of Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel.
Relate to a kind of novel steel products, be a kind of in low carbon manganese steel in the steel trace add niobium, v element and to the cold accurate control of control preparation process control, prepare and need not the high strength plate of moderate thickness that is used for shipbuilding that modifier treatment can reach high intensity levels.
Background technology
Along with the development of global shipbuilding, ship body largeization, lightness have become the main developing direction of world's shipbuilding, and be more and more higher to the specification of quality of ship plate.Because the deck of boat steel of high intensity levels has the intensity height, good combination property, can alleviate hull mass, improve advantages such as weight-carrying capacity, its usage quantity is increasing year by year, has also greatly driven the development in China low-alloy high-strength deck of boat steel market.Common intensity deck of boat steel can not satisfy the requirement of hull structural steel, and the application percentage of high strength ship plate steel constantly raises simultaneously, makes it have vast market prospect.
High-strength ship plates is as one of higher steel grade of a kind of quality grade, be mainly used in building large ship and offshore oil, drilling unit etc., its member faces problems such as abominable, the huge assumed load of environment for use and high stress concentration, maintenance difficulties be big, therefore, require not only intensity high and low temperature good toughness of deck of boat steel, and have performances such as low, the good welding of certain erosion resistance, resistance to fatigue and carbon equivalent and machine-shaping.Obtain favorable tissue and performance, at first want the combined process condition to determine the smelting component of steel, realize by control technology and equipment then.
Domestic when making this type of plate of moderate thickness, adopt the technical process of hot metal pretreatment → converter smelting → ladle furnace refining → sheet billet continuous casting → process furnace → controlled rolling → modifier treatment mostly, because steel-making has been adopted the ladle refining furnace refining and has been rolled back steel plate modifier treatment, cause the production cycle to prolong greatly, production cost is corresponding raising also.The content of carbon, silicon, manganese element has great influence to the steel final properties in the general steel, and designing the add-on of the content of rational carbon, silicon, manganese element and microalloy element niobium, vanadium and adopting suitable cooling controlling and rolling controlling process is the key of preparation.Practice shows, thereby adds niobium in steel, v element obtains need not the steel plate that modifier treatment can reach the above tensile strength of 550MPa, and have good plasticity and toughness.By controlled rolling and controlled cooling, make the structure refinement of steel, control carbonitride the separating out in process of cooling of niobium, vanadium simultaneously, thereby reach the purpose that improves the steel obdurability.
Summary of the invention
The objective of the invention is at above-mentioned technical Analysis and existing problems, a kind of Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel is provided, this ship steel intensity high and low temperature good toughness, make carbon equivalent low, performances such as good welding and machine-shaping are arranged, make that the thick deck of boat has good erosion resistance and resistance to fatigue in the high strength, be applicable to fields such as large ship, offshore drilling platforms.
Technical scheme of the present invention:
A kind of Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel, composition comprises carbon (C), silicon (Si), manganese (Mn), vanadium (V), niobium (Nb), phosphorus (P), sulphur (S), aluminium (Al) and iron (Fe), and the weight percentage of each component is: C0.10-0.15%; Si0.25-0.35%; Mn1.50-1.70%; V0.06-0.09%; Nb0.23-0.32%; P＜0.025%; S＜0.020%, Al0.402-0.424%, surplus is Fe and other unavoidable impurities.
The preparation method of described Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel is: behind blast furnace ironmaking, molten iron pretreatment desulfurizing, converter smelting decarburization and the back deoxidation of molten steel that heats up, adding niobium, vanadium make its microalloying, after the deoxidation of ar blowing refining aluminium wire, carry out sheet billet continuous casting.
The application of a kind of described Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel, be used for rolling plate of moderate thickness material peculiar to vessel, moulding process is: Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel is carried out the pipe continuous casting under 1210 ℃, the pipe soaking is rolled after 1080-1200 ℃, in 960 ± 20 ℃ of open rollings, total deformation control is 100%, 840 ± 20 ℃ of finish to gauges; Control cooling is opened coldly in 860 ± 20 ℃, speed of cooling is controlled at 5-21 ℃/s, and 620 ± 20 ℃ of ends are cold; Make plate of moderate thickness material finished product peculiar to vessel after the finishing.
Technical Analysis of the present invention:
In composition when design, adopt and carry out microalloying on carbon, manganese strengthened basis, reduces the carbon content that toughness and welding property are had the greatest impact, and guarantees still can obtain higher intensity under low carbon content situation, to guarantee excellent comprehensive performances.Carbon improves the intensity of steel by solution strengthening, but extremely harmful to toughness, plasticity and welding property.Manganese mainly plays solution strengthening, and the compensation carbon content reduces the loss of strength that causes.Manganese can also synthesize MnS with sulfuration simultaneously, alleviates the deleterious effect of sulphur.The Si-Mn alloy that the content of silicon and when steel-making add has much relations, so after manganese content determined, siliceous amount mark was approximately 0.20%～0.40%.Aluminium is important reductor in smelting, forms the infusible compound AlN that small and disperseds distribute and works the grain growth effect that hinders at neutralize other elements of steel, can crystal grain thinning, improve the grain coarsening temperature of steel.Phosphorus, sulphur are the element that is harmful to very much in steel, influence plasticity and the toughness of steel plate, and for guaranteeing every performance, sulphur, phosphorus content should be low as far as possible.Also want strict control nitrogen content simultaneously, nomadic nitrogen significantly reduces low-temperature impact toughness.Niobium can be combined into carbide, nitride and carbonitride with carbon nitrogen, and these compounds at high temperature dissolve, and separates out at low temperatures, and its effect shows as: hinder original austenite grains during heating and grow up; Grain growth behind inhibition recrystallize and the recrystallize in the operation of rolling; When low temperature, play the precipitation strength effect.In steel, add niobium, vanadium, can play the effect of crystal grain thinning and precipitation strength; Wherein niobium can the strongly inhibited austenite recrystallization, improves austenite recrystallization temperature, enlarges austenite non-recrystallization district temperature range, thus the non-recrystallization district controlled rolling in realizing in a big way.
Heating temperature is mainly according to solubleness and the AUSTENITE GRAIN COARSENING temperature of microalloy element in the moulding process.The temperature that heat-processed is had relatively high expectations and time enough are with dissolving carbide and uniform formation, and the niobium nitride of solid solution can not improve austenitic alligatoring temperature, stop grain growth; Niobium in the continuously cast bloom mainly exists with the form of oarse-grained carbonitride, only is solidly soluted into the effect that niobium in the austenite just can play crystal grain thinning and precipitation strength in heat-processed.Should guarantee niobium fully dissolving in austenite during heating, when soaking temperature is low, will have the not molten microalloy carbon of part, nitride, will reduce the effect of microalloy carbon, nitride inhibition austenite recrystallization; Soaking temperature is too high, will make the remarkable alligatoring of austenite crystal, influences the thinning effect of final deformation crystal grain.
In cooling controlling and rolling controlling process, rolling employing recrystallization zone and non-recrystallization district two stage rolling, the rolling of a stage carries out in the austenite recrystallization district, carries out crystal grain thinning by austenitic recrystallize repeatedly.Can make austenite recrystallization complete under the high temperature, therefore under the situation that equipment allows, increase the draft of single pass, crystal grain thinning is for fear of causing mixed crystal, every time draft must not be less than 15%, two-stage is rolling carries out in austenitic non-recrystallization district, obtains the deformed austenite that fully flattens, accumulating dislocation, create more nucleation site, promote to obtain tiny phase-change organization after the phase transformation.Niobium nitride and vanadium nitride rely on deformation induced separating out in the operation of rolling, also can stop austenite crystal to be grown up, thereby make the austenite crystal refinement; Fully the niobium carbide of solid solution and vanadium carbide are separated out in process of cooling intergranular precipitation, stop crystal boundary and dislocation migration, thus the intensity of significantly improving.Grain refining and precipitation precipitation strength effect impel steel to have good obdurability.
Advantage of the present invention is: this ship steel intensity high and low temperature good toughness, make carbon equivalent low, performances such as good welding and machine-shaping are arranged, make that the thick deck of boat has good erosion resistance and resistance to fatigue in the high strength, tensile strength reaches more than 530 ± 20MPa, is applicable to fields such as large ship, offshore drilling platforms.
Description of drawings
Fig. 1 is the dynamic cooling controlling and rolling controlling process temperature control of this low carbon high-strength degree low alloy steel peculiar to vessel curve.
Fig. 2 is that this low carbon high-strength degree low alloy steel peculiar to vessel is through the dynamic CCT curve under different cooling speed after the austenite high temperature deformation.
The normal temperature microstructure picture of Fig. 3 under different cooling speed, obtaining after this low carbon high-strength degree low alloy steel peculiar to vessel high temperature deformation.
Embodiment
Embodiment:
A kind of Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel, composition comprises C, Si, Mn, V, Nb, P, S, Al and Fe, and the weight percentage of each component is: C0.10%, Si0.26%, Mn1.55%, V0.09%, Nb0.32%, P0.009%, S0.010%, Al0.412%, surplus are Fe and other unavoidable impurities.
The preparation method of described Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel is: behind blast furnace ironmaking, molten iron pretreatment desulfurizing, converter smelting decarburization and the back deoxidation of molten steel that heats up, adding niobium, vanadium make its microalloying, after the deoxidation of ar blowing refining aluminium wire, carry out sheet billet continuous casting.
The application of described Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel, be used for rolling plate of moderate thickness material peculiar to vessel, moulding process is: Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel is carried out the pipe continuous casting under 1210 ℃, the pipe soaking is rolled after 1080 ℃, in 980 ℃ of open rollings, 880 ℃ of finish to gauges, total deformation is controlled 100%; Control cooling is opened coldly in 880 ℃, speed of cooling is controlled at 5-21 ℃/s, and 640 ℃ of ends are cold; Make plate of moderate thickness material finished product peculiar to vessel after the finishing.Fig. 1 is the dynamic cooling controlling and rolling controlling process temperature control of this low carbon high-strength degree low alloy steel peculiar to vessel curve.
Fig. 2 is that this low carbon high-strength degree low alloy steel peculiar to vessel is through the dynamic CCT curve under different cooling speed after the austenite high temperature deformation, this curve is relevant with the materials chemistry component, the range of choice of speed of cooling is provided, in the cooling rate scope of 5-21 ℃/s, just can have obtained microstructure shown in Figure 3 and reach requirement of strength.。
The normal temperature microstructure picture of Fig. 3 under different cooling speed, obtaining after this low carbon high-strength degree low alloy steel peculiar to vessel high temperature deformation, wherein: when a) cooling rate is 5 ℃/s, tensile strength 521MPa; When b) cooling rate is 11 ℃/s, tensile strength 529MPa; When c) cooling rate is 17 ℃/s, tensile strength 537MPa; When d) cooling rate is 21 ℃/s, tensile strength 548MPa.
Claims (2)
1. Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel, it is characterized in that: composition comprises carbon (C), silicon (Si), manganese (Mn), vanadium (V), niobium (Nb), phosphorus (P), sulphur (S), aluminium (Al) and iron (Fe), and the weight percentage of each component is: C0.10-0.15%; Si0.25-0.35%; Mn1.50-1.70%; V0.06-0.09%; Nb0.23-0.32%; P＜0.025%; S＜0.020%, Al0.402-0.424%, surplus is Fe and other unavoidable impurities.
2. the application of a described Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel, it is characterized in that: be used for rolling plate of moderate thickness material peculiar to vessel, moulding process is: Nb-V combined microalloying low carbon high-strength degree peculiar to vessel low alloy steel is carried out the pipe continuous casting under 1210 ℃, the pipe soaking is rolled after 1080-1200 ℃, in 960 ± 20 ℃ of open rollings, total deformation control is 100%, 860 ± 20 ℃ of finish to gauges; Control cooling is opened coldly in 860 ± 20 ℃, speed of cooling is controlled at 5-21 ℃/s, and 620 ± 20 ℃ of ends are cold; Make plate of moderate thickness material finished product peculiar to vessel after the finishing.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106048178A (en) * | 2016-07-16 | 2016-10-26 | 柳州科尔特锻造机械有限公司 | Hot rolling process of steel |
| CN113322365A (en) * | 2021-05-19 | 2021-08-31 | 北京理工大学 | Method for simultaneously improving strength and plasticity of low-carbon low-alloy steel |
Citations (3)
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| CN101748328A (en) * | 2009-12-31 | 2010-06-23 | 首钢总公司 | Ship structure steel plate capable of being welded with high liner energy and method for producing same |
| CN102605280A (en) * | 2012-03-15 | 2012-07-25 | 宝山钢铁股份有限公司 | Ultra-thick high-strength high low-temperature toughness steel plates for ocean platforms and production method thereof |
| CN102899569A (en) * | 2012-10-23 | 2013-01-30 | 秦皇岛首秦金属材料有限公司 | Production method of wide and heavy steel plate with excellent ultra-low-temperature toughness used for offshore wind power |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101748328A (en) * | 2009-12-31 | 2010-06-23 | 首钢总公司 | Ship structure steel plate capable of being welded with high liner energy and method for producing same |
| CN102605280A (en) * | 2012-03-15 | 2012-07-25 | 宝山钢铁股份有限公司 | Ultra-thick high-strength high low-temperature toughness steel plates for ocean platforms and production method thereof |
| CN102899569A (en) * | 2012-10-23 | 2013-01-30 | 秦皇岛首秦金属材料有限公司 | Production method of wide and heavy steel plate with excellent ultra-low-temperature toughness used for offshore wind power |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106048178A (en) * | 2016-07-16 | 2016-10-26 | 柳州科尔特锻造机械有限公司 | Hot rolling process of steel |
| CN113322365A (en) * | 2021-05-19 | 2021-08-31 | 北京理工大学 | Method for simultaneously improving strength and plasticity of low-carbon low-alloy steel |
| CN113322365B (en) * | 2021-05-19 | 2022-05-20 | 北京理工大学 | Method for simultaneously improving strength and plasticity of low-carbon low-alloy steel |
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Application publication date: 20130710 |