CN101775552B - High-strength high-flexibility low-yield-ratio fire resistant steel and production method thereof - Google Patents
High-strength high-flexibility low-yield-ratio fire resistant steel and production method thereof Download PDFInfo
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- CN101775552B CN101775552B CN 200910045146 CN200910045146A CN101775552B CN 101775552 B CN101775552 B CN 101775552B CN 200910045146 CN200910045146 CN 200910045146 CN 200910045146 A CN200910045146 A CN 200910045146A CN 101775552 B CN101775552 B CN 101775552B
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Abstract
The invention provides high-strength fire resistant steel with the room-temperature yield strength being more than 460 MPa, the yield ratio being smaller than 0.80, the high-temperature yield strength at 600 DEG C being more than two thirds of the room-temperature yield strength (i.e. more than 307 MPa) and favorable impact flexibility, which comprises the following components by weight percent: 0.05 to 0.14 percent of C, 0.15 to 0.50 percent of Si, 0.5 to 1.2 percent of Mn, equal to or less than 0.025 percent of P, equal to or less than 0.015 percent of S, 0.10 to 0.40 percent of Cu, 0.10 to 0.50 percent of Ni, 0.015 to 0.050 percent of Nb, 0.005 to 0.040 percent of Ti, 0.010 to 0.050 percent of V, 0.10 to 0.50 percent of Cr, 0.20 to 0.50 percent of Mo, 0.015 to 0.05 percent of Al, Fe and foreign matters. The invention also provides a production method of the fire resistant steel, which comprises the following steps: liquid steel is obtained through vacuum melting, and the liquid steel is cast to form a billet; after the billet is heated to 1150 to 1250 DEG C and is maintained for 1.5 to 2.5 hours, the billet is controlled to be rolled to the thickness of a finished product plate, the final rolling temperature is controlled about 820 to 950 DEG C, and the steel plate is air cooled or is air cooled after being fast water cooled to 450 to 650 DEC C after the rolling.
Description
Technical field
The invention belongs to low alloy steel and make the field, relate to a kind of room temperature yield strength greater than 460MPa, yield tensile ratio less than 0.80,600 ℃ of high-temperature yield strength greater than the room temperature yield strength 2/3 (namely 〉=307MPa), and have high-strength fireproof steel and a production method thereof of good impelling strength.
Background technology
The common building steel, such as SN400 in the JIS standard and SN490 steel, Q235 in the Chinese national standard and Q345 etc., more than 350 ℃ during high temperature yield strength quickly fall to below 2/3 of its room temperature yield strength, have hardly supporting capacity during to 600 ℃, can not satisfy the design requirements of Modern Steel Structure Highrise buildings.In order to improve the refractory ability of steel construction, the eighties, the Japanology personnel proposed the concept of refractory steel.To have developed refractory temperature be 600 ℃ Fire-resistant Steels Used in Buildings by add the alloying elements such as a small amount of chromium (Cr), molybdenum (Mo), niobium (Nb) in steel, and 600 ℃ yield strength remains on more than 2/3 of house temperature.The prosperity and development of steel building have promoted the research and development of refractory steel.At present, refractory steel is mainly take yield strength 235MPa and 345MPa as main (Japanese 400MPa level steel and 490MPa level steel), and mainly by adding the intensity of more Mo when guaranteeing high temperature, Mo content surpasses 0.50% usually for it.In recent years, Japan has developed the refractory steel (590MPa rank) of yield strength 440MPa level, and the Mo content in its steel has reached 0.7%, and the weldability of steel grade is very poor and cost is higher, has seriously restricted its application.At present, refractory steel research forward position mainly contains:
(1) improves yield strength, reduction yield tensile ratio; (2) content of reduction alloying element.
The patent CN 1524976A " refractory steel and manufacture method thereof " of Anshan Iron and Steel Company's application provides the high-performance refractory steel of intensity rank 235MPa and 345MPa, it is take Cr, Mo alloying element as main, be aided with the elements such as copper (Cu), niobium (Nb), vanadium (V), nickel (Ni), titanium (Ti), aluminium (Al), boron (B) and rare earth (RE), adopt controlled rolling and Controlled cooling process production.The refractory steel intensity rank that this patent provides is lower, and alloying element content is higher.Nippon Steel provides the steel of the high-strength fireproof more than a kind of yield strength 440MPa at the patent CN 101111621A " high-strength fireproof steel and manufacture method thereof that weldability and gas cutting are good " of China's application, it is the complex intensifying effect by Mo and Nb mainly, reach and improve intensity to more than the 440MPa, and with below the Mo content to 0.70%.Its manufacturing process is online direct quenching tempering or off-line Q-tempering technique.The alloying element content of this refractory steel is higher, and Mo content is about 0.5% even higher, and yield tensile ratio is higher, greater than 0.80.The patent JP 2077523 " Production of buildinglow yield ratio steel having excellent fire resistance and building steelmaterial using same steel " of Nippon Steel's application provides a kind of low-yield-ratio fire resistant steel and manufacture method thereof, steel plate room temperature yield strength is from 235MPa to 440MPa, yield tensile ratio≤0.80,600 ℃ yield strength/room temperature yield strength 〉=2/3.Its manufacture method is 1100-1300 ℃ of heating, and finishing temperature 800-1000 ℃, air cooling is to room temperature subsequently.This refractory steel plates yield strength is relatively low, and alloying element content is higher.
Summary of the invention
The high-performance refractory steel and the manufacture method thereof that the purpose of this invention is to provide a kind of high-intensity high-tenacity low yield strength ratio.This refractory steel has good mechanical property: yield strength 〉=460Pa, yield tensile ratio≤0.80,600 ℃ high-temperature yield strength greater than 2/3 room temperature yield strength (〉=307MPa), and have good impelling strength.Suitable application area mainly is that steel building and other require the field of steel structure of fire performance, such as multi-storied garage, supermarket etc.
Refractory steel provided by the invention, its chemical ingredients (by weight percentage) is: C:0.05～0.14, Si:0.15～0.50, Mn:0.5～1.2, P≤0.025, S≤0.015, Cu:0.10-0.40, Ni:0.10-0.50, Nb:0.015-0.050, Ti:0.005-0.040, V:0.010-0.050, Cr:0.10-0.50, Mo:0.20-0.50, Al:0.015-0.05, surplus are Fe and inevitably are mingled with.
C content is controlled at 0.05～0.14% in the refractory steel of the present invention.C is one of strengthening element cheap in the steel, for guaranteeing the high strength of steel, is defined as 0.05% under the C content.But, when C content is too much, will have a negative impact to the obdurability of steel coupling and weldability etc., thus C content on be defined as 0.14%.
Si content is controlled at 0.15～0.50% in the refractory steel of the present invention.Si is one of bioelement of deoxidation in steel making, and Si can improve the intensity of steel by the solution strengthening mode.But Si has disadvantageous effect to weldability and toughness etc., must the restriction higher limit.
To be controlled at 0.5～1.2%, Mn also be one of bioelement of deoxidation in steel making to Mn content in the refractory steel of the present invention, and Mn guarantees that intensity is indispensable, is limited to 0.5% under it.But the Mn too high levels has disadvantageous effect to the welding property of steel, and may make center segregation more serious, and its upper limit is controlled to be 1.2%.
P content≤0.025%, S content≤0.015% in the refractory steel of the present invention.S and P are the detrimental impurity elements in the steel, and too high levels can worsen the toughness of steel, therefore answer sulphur, phosphorus content in the reduce steel.
Cu content is controlled at 0.10-0.40% in the refractory steel of the present invention.Cu is present in the steel with tiny precipitation particles state usually, produces the precipitation strength effect.Cu not only can improve intensity, but also can improve the atmospheric corrosion resistance of steel.But will cause in heating steel billet or the course of hot rolling when Cu content is high to crack, worsen the steel surface performance, so the upper limit be controlled at 0.40%.
Ni content is controlled at 0.10-0.50% in the refractory steel of the present invention.Ni can improve its low-temperature flexibility when improving hardness of steel.For the effect that makes Ni is brought into play, need at least 0.10%.Ni can reduce the tendency that contains Cu steel generation steel surface defective simultaneously.But Ni is noble element, so the Ni upper content limit is controlled at 0.50%.
Nb content is controlled to be 0.015-0.05% in the refractory steel of the present invention.Nb is strong carboritride forming element, by separating out carboritride in the process of cooling after rolling, produces the intensity that refined crystalline strengthening and precipitation strength are used for improving steel.In addition, the precipitate solvent temperature of Nb is higher, can improve steel 600 ℃ intensity, improve fire performance, but the Nb too high levels may have a negative impact also.
Ti content is controlled to be 0.005-0.040% in the refractory steel of the present invention.Ti is a kind of strong carbonitride forming element, and its carbonitride has higher fusing point, and growing up of austenite crystal has inhibition during to heating.And separating out in the process of cooling will be improved the yield strength of steel after rolling, and favourable to the hot strength of steel.But thick precipitation particles may appear in the Ti too high levels, and its upper limit is controlled to be 0.040%.
V content is controlled to be 0.010-0.050% in the refractory steel of the present invention.V is strong carboritride forming element, and strengthening effect is similar to Nb, but the effect less.Obviously worsen the toughness of low-temperature flexibility, the especially welded heat affecting zone of steel when V content is higher, its upper limit is controlled to be 0.050%.
Cr content is controlled at 0.10-0.50% in the refractory steel of the present invention.Cr is the element that improves hardening capacity, and the strong hardness of steel is increased.But the Cr too high levels will affect the toughness of steel, and cause temper brittleness, and its upper limit is controlled to be 0.50%.
Mo content is controlled at 0.20-0.50% in the refractory steel of the present invention.Mo is the effective element that improves the steel hot strength, and Mo content is higher, and its hot strength is higher.But the Mo cost is higher, and causes that the steel weldability reduces, thereby Mo content maximum is controlled at 0.50%.
Al content is controlled at 0.015-0.05% in the refractory steel of the present invention, and Al is one of effective deoxidant element, and can form nitride and come crystal grain thinning.The Al too high levels will be damaged the toughness of steel, and the welding heat affected also variation of toughness that obtains.
Refractory steel of the present invention, the preferred content range of its composition are that C:0.06～0.09, Si:0.25～0.35, Mn:0.8～1.0, P≤0.025, S≤0.015, Cu:0.20-0.30, Ni:0.15-0.35, Nb:0.025-0.035, Ti:0.015-0.025, V:0.025-0.045, Cr:0.25-0.40, Mo:0.20-0.40, Al:0.025-0.045, surplus are Fe and inevitably are mingled with.
The present invention also provides the production method of this high-strength high-flexibility low-yield-ratio fire resistant steel, and typical process flow comprises:
Adopt vacuum metling to obtain to have the molten steel of composition of the present invention and content, and be cast into steel billet; After steel billet reheated 1150-1250 ℃ of insulation 1.5-2h, controlled rolling was to the finished product thickness of slab, and finishing temperature control is about 820-950 ℃, air cooling after rolling rear steel plate air cooling or rapid water and being chilled to 450～650 ℃.
Refractory steel of the present invention has following features:
1) more expensive alloying element content is few, and cost is lower;
2) adopt control to prick cooling control technology and produce, need not to roll postheat treatment.Production technique is simple, is easy to production operation;
3) have high strength, low yield strength ratio, good toughness and weldability, and have good hot strength, can satisfy steel construction to the requirement of low yield strength ratio high-strength refractory steel.
The contrast of the composition range of steel grade, process system and mechanical property sees the following form in refractory steel of the present invention and the prior art:
Embodiment
According to the chemical ingredients requirement of refractory steel of the present invention, adopt the 500kg vacuum induction furnace smelting, the Chemical Composition that obtains steel sees the following form, and surplus is Fe and inevitably is mingled with.Molten steel watered builds up steel billet, subsequently with heating steel billet to 1150-1250 ℃, insulation 2h, with steel ingot in the intermediate slab that is rolled into 60mm more than 1000 ℃, slab band temperature finally is rolled into the 20mm Plate Steel to 850-980 ℃ with steel billet, and finishing temperature is controlled to be 820-950 ℃.Steel plate rolls rear Direct Air-Cooled to room temperature, or take rapid water be chilled to 450～650 ℃ (the about 10-30 of cooling rate ℃/s) after air cooling to room temperature.Concrete processing parameter and mechanical property see the following form.Chemical Composition, complete processing and the corresponding mechanical property thereof of aforesaid contrast steel grade have been listed file names with in the table.
The mechanical properties of steel plate is measured and is carried out according to GB/T 228-2002 " metallic substance tensile test at room temperature method ", and specimen size is M16 Φ 10L120; The high temperature tensile strength of steel plate is measured and is carried out according to GB/T 4338-2006 " Metal Materials At High Temperature stretching test method ", specimen size M16 Φ 10L112, insulation was 15 minutes after sample was heated to 600 ℃, began subsequently tension test, and sample keeps 600 ℃ in the drawing process.The impelling strength of steel plate is measured and is carried out specimen size 10*10*55, v-notch according to GB/T 229-2007 " the metallic substance summer is than pendulum impact test method ".
This shows that the present invention adopts control bundle cooling control technology can obtain the room temperature yield strength and surpasses 460MPa by adding less precious metal element, yield tensile ratio is lower than 0.80%, 600 ℃ of yield strength greater than 307MPa, and has the high-strength fireproof steel of excellent in toughness.Refractory steel of the present invention can be widely used in steel building and other requires the field of steel structure of fire performance.
Claims (3)
1. the manufacture method of a refractory steel, its composition and weight percentage are: C:0.05～0.14, Si:0.15～0.50, Mn:0.5～1.2, P≤0.025, S≤0.015, Cu:0.10-0.40, Ni:0.10-0.50, Nb:0.015-0.050, Ti:0.005-0.040, V:0.010-0.050, Cr:0.10-0.50, Mo:0.20-0.50, Al:0.015-0.05, surplus are Fe and inevitably are mingled with;
The manufacturing process of described steel comprises:
Adopt vacuum metling to get molten steel, and be cast into steel billet; After steel billet reheated 1150-1250 ℃ of insulation 1.5-2.5h, controlled rolling was to the finished product thickness of slab, and finishing temperature is controlled to be 820-950 ℃, air cooling after rolling rear steel plate air cooling or rapid water and being chilled to 450～650 ℃.
2. the method for claim 1, it is characterized in that its composition and weight percentage are: C:0.06～0.09, Si:0.25～0.35, Mn:0.8～1.0, P≤0.025, S≤0.015, Cu:0.20-0.30, Ni:0.15-0.35, Nb:0.025-0.035, Ti:0.015-0.025, V:0.025-0.045, Cr:0.25-0.40, Mo:0.20-0.40, Al:0.025-0.045, surplus are Fe and inevitably are mingled with.
3. the refractory steel made of method as claimed in claim 1 or 2.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102400053B (en) * | 2010-09-07 | 2014-03-12 | 鞍钢股份有限公司 | Steel plate for building structure with yield strength of 460 MPa, and manufacturing method thereof |
| CN102433507B (en) * | 2012-01-16 | 2013-12-25 | 江苏省沙钢钢铁研究院有限公司 | Low yield ratio and high strength weldable steel plate and preparation technology thereof |
| CN102719753B (en) * | 2012-05-28 | 2013-11-13 | 江苏省沙钢钢铁研究院有限公司 | Low-yield-ratio high-strength steel plate and manufacturing method thereof |
| CN104862606A (en) * | 2015-05-30 | 2015-08-26 | 广西盛隆冶金有限公司 | Steel resistant to marine corrosion |
| CN108085589A (en) * | 2017-11-22 | 2018-05-29 | 南阳汉冶特钢有限公司 | A kind of 120mm~150mm thickness ultralow-temperature flexibility fire-resistant and weather-resistant steel and its production method |
| CN112813352A (en) * | 2021-01-21 | 2021-05-18 | 江苏沪之通金属制品有限公司 | Corrosion-resistant metal material and preparation method thereof |
| CN115927952B (en) * | 2022-10-21 | 2024-02-06 | 燕山大学 | 690 MPa-grade hydrogen-induced delayed fracture resistant low-weld crack sensitivity quenched and tempered steel and manufacturing method thereof |
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