CN1854325A - High-strength high-ducility bainite non-quenched and tempered steel plate with small acoustic anisotropism - Google Patents
High-strength high-ducility bainite non-quenched and tempered steel plate with small acoustic anisotropism Download PDFInfo
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- CN1854325A CN1854325A CNA2006100683719A CN200610068371A CN1854325A CN 1854325 A CN1854325 A CN 1854325A CN A2006100683719 A CNA2006100683719 A CN A2006100683719A CN 200610068371 A CN200610068371 A CN 200610068371A CN 1854325 A CN1854325 A CN 1854325A
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- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47L—DOMESTIC WASHING OR CLEANING; SUCTION CLEANERS IN GENERAL
- A47L13/00—Implements for cleaning floors, carpets, furniture, walls, or wall coverings
- A47L13/10—Scrubbing; Scouring; Cleaning; Polishing
- A47L13/20—Mops
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Abstract
The invention discloses a steel sheet, which comprises the following parts: 0.02-0.08% C, 0.05-0.50% Si, 1.0-2.5% Mn, less than 0.015% P(not contain 0%), less than 0.006% S (not contain 0%), 0.50-1.50% Cr, 0.005-0.030% Ti, 0.0030-0.0080% N, less than 0.005% (contain 0%) Nb, 0.0006-0.0021% solutionized B, wherein the duty factor of bainite is over 90%, whose even breadth rate is between 1.8 and 5.3 with old austenite crystallization grain in the plate thickness profile paralleled the main rolling direction with stretching resistance strength over 570Mpa. The sound of steel sheet is little aeolotropy, which is non-tempering steel sheet with excellent toughness.
Description
Technical field
The present invention relates to the little high-intensity high-tenacity bainite non-quenched and tempered steel plate of a kind of sound anisotropy, it is little particularly to relate to the sound anisotropy, and the tensile strength of tenacity excellent is the above non-quenching and tempering type bainite steel plate of 570MPa.
Background technology
As the large structure of building structure and bridge etc. with employed steel plate in, require it to have high strength and high tenacity.And, as for building and bridge with and when being used, because if having defective in steel plate inside, then this part becomes the starting point of destroying generation easily, so generally need utilize ultrasonic test to investigate having or not of defect part.But, because change significantly, and can not detect the correct position of welding flaw portion, so in steel plate, also require so-called " sound anisotropy " little with ultrasonic test according to the flaw detection direction velocity of sound.
In addition, except that above-mentioned various characteristics, the viewpoint that reduces from manufacturing cost, and seek so-called non-modifiedly, even that is to say at off-line and do not carry out Q-tempering, also can guarantee above-mentioned characteristic fully.
The manufacture method of the non-hardened and tempered steel of and low yielding ratio few as the sound anisotropy, for example open shown in the flat 01-301819 communique the spy, when near γ/α 2 phase regions Ar3 are rolled, not only processing ferrite generates, yield ratio rises significantly, and because the generation of set tissue, the sound anisotropy also becomes greatly, establishes the final rolling following Ar3 of being limited to thus.And point out, add the Nb that should guarantee intensity more than 0.003% and realize precipitation-hardening.But,,, have the sound anisotropy to become big tendency though can easily guarantee intensity if Nb content is increased.
Te Kaiping 09-256042 communique is that paragraph " 0035 " illustrates about the technology of " manufacture method of the anisotropic little High Strength Steel of the few and sound of material deviation ", " in order to make the sound anisotropy little, below shown in manufacturing process be suitable for utilizing.Promptly, the steel billet that composition is adjusted into above-mentioned essentially consist is implemented after the shaping processing of hot rolling etc., at first, cool off by the temperature more than the reheat to 860 ℃, for the formed bainite structure of the process of cooling after hot-work becomes austenite once more mutually, the formed phase transformation set of the process of cooling after hot-work tissue disappears, by the cooling behind the continuation reheat, with above-mentioned same equalization, and be formed with the not bainite structure of set tissue.Consequently, the sound anisotropy of steel diminishes ".But, this method will be heat-treated after hot rolling, is not to relate to non-quenched and tempered steel plate.Consider in addition in order to guarantee excellent toughness simultaneously, be necessary to improve.
Open in the flat 11-193445 communique the spy, the welding that shows tensile strength in the toughness of the thickness direction of rolling ortho states lower steel plate and sound anisotropy excellence and be the 590MPa level is with utmost point Plate Steel and manufacture method thereof, it is expressed as hot-rolled condition, particularly by Heating temperature being made as 1050 ℃～1250 ℃, realize the recrystal grain refinement and guarantee toughness, and by being controlled at accumulative total draft and the rolling outlet temperature in the temperature province below 950 ℃, thereby reduce the sound anisotropy.But consider for sound is anisotropic and guarantee more excellent toughness simultaneously, and be necessary to improve.
And, open in the 2002-053912 communique the spy, publicity the sound anisotropy little, the manufacture method of the non-quenching and tempering type low yield ratio high tension steel plate of welding property excellent, it is pointed out specifically, by making the accumulative total draft in austenitic non-recrystallization district is below 60%, and establish rolling outlet temperature for more than (austenitic non-recrystallization temperature-80 ℃), the ratio of shear wave velocity of sound value CSL (the m/s)/CSC (m/s) that direction of vibration is obtained as L direction (main rolling direction) and C direction (with the direction at L direction right angle) than CSL/CSC[by the shear wave velocity of sound of JIS Z 3060 regulations] value can be below 1.02.And open in the 2004-300567 communique the spy and to point out,, then can reach the shear wave velocity of sound than being low sound anisotropy below 1.02 if the mean aspect ratio of old austenite grain (ratio of " major diameter/minor axis ") is below 1.8.But, in these technology, consider that sound is anisotropic and guarantee more excellent toughness simultaneously, also require further to improve.
Summary of the invention
The present invention In view of the foregoing carries out, and its purpose is, provides a kind of sound anisotropy little, and the tensile strength of tenacity excellent is the above bainite non-quenched and tempered steel plate of 570MPa.
Steel plate of the present invention, contain:
C:0.02～0.08% (meaning of quality %, below identical),
Si：0.05～0.50％，
Mn：1.0～2.5％，
P:0.015% following (not containing 0%),
S:0.006% following (not containing 0%),
Cr：0.50～1.50％，
Ti：0.005～0.030％，
N：0.0030～0.0080％，
Solid solution Nb:0.005% following (containing 0%),
Solid solution B:0.0006～0.0021%;
Bainite contains more than 90% in space factor (lamination factor);
The mean aspect ratio of the old austenite crystallization particle diameter in the thickness of slab section parallel with main rolling direction (median size of the median size of main rolling direction/thickness of slab direction) is above 1.8 but below 5.3;
Tensile strength is more than the 570MPa.
In steel of the present invention, as required, contain following composition also for effective,
(a) from Cu:0.05～1.20%, Ni:0.05～1.20%, and the group that constitutes of Mo:0.03～0.50% optional a kind with,
(b) Ca:0.0005～0.005% and/or REM:0.0003～0.003%, corresponding these compositions that contained can further improve the characteristic of steel plate.
Steel plate of the present invention, because have high strength and high tenacity, and the sound anisotropy is little, so the most suitable as the large structure usefulness of building structure and bridge etc.
Description of drawings
Fig. 1 is the graphic representation of the relation of expression long-width ratio and broken face transition temperature (vTrs).
Fig. 2 is the graphic representation of expression long-width ratio and the anisotropic relation of sound.
Fig. 3 is expression Nb amount and breaks the graphic representation of the relation of face transition temperature (vTrs).
Fig. 4 is the graphic representation of the relation of expression solid solution B amount and tensile strength (TS).
Fig. 5 is the graphic representation of the relation of expression solid solution B content and broken face transition temperature (vTrs).
Embodiment
Present inventors, for modified to obtain the sound anisotropy little with non-, the tensile strength of tenacity excellent is the above bainite steel plate of 570MPa, and study with keen determination, find the mean aspect ratio (median size of the median size of main rolling direction/thickness of slab direction) of the old austenite crystallization particle diameter in the control thickness of slab section parallel with main rolling direction, and be controlled to be grouped into very important.
Fig. 1 represents above-mentioned long-width ratio and relation as the broken face transition temperature (vTrs) of flexible index, and long-width ratio and broken face transition temperature either party all try to achieve with the method shown in the aftermentioned embodiment.Fig. 1 if above-mentioned long-width ratio surpasses 1.8, can guarantee brokenly in view of the above that then face transition temperature (vTrs) is below-50 ℃ and significantly excellent toughness as can be known thus.Above-mentioned long-width ratio is more than 2.8, can guarantee brokenly that face transition temperature (vTrs) is below-60 ℃ and more excellent toughness, so preferred.Further preferred long-width ratio is more than 4.3.
In the present invention, guaranteeing the so excellent flexible while that set the upper limit of long-width ratio in order to ensure low sound anisotropy, the control of carrying out long-width ratio is very important.
Fig. 2 represents above-mentioned long-width ratio and the anisotropic relation of sound, and any tries to achieve long-width ratio and sound anisotropy (the shear wave velocity of sound is than CSL/CSC) by the direction shown in the embodiment described later.From then on Fig. 2 is at least 1.02 or hereunder in order to make the shear wave velocity of sound than CSL/CSC, and reduces the sound anisotropy as can be known, and above-mentioned long-width ratio is made as below 5.3 very necessary.Because above-mentioned long-width ratio is below 4.6, the sound anisotropy is littler, and institute thinks preferred.From obtaining the anisotropic viewpoint of littler sound, more preferably long-width ratio is below 3.7.
In order to ensure above-mentioned toughness, and guarantee high strength, above-mentioned long-width ratio is controlled to be above 1.8, and the solid solution Nb amount in the control steel, also have solid solution B amount and Cr amount very effective.
Fig. 3 is expression solid solution Nb amount and the relation of breaking face transition temperature (vTrs), and the composition beyond solid solution Nb makes in the steel that solid solution Nb content changes between 0～0.027% in specialized range, has measured broken face transition temperature (vTrs).Fig. 3 is below-50 ℃ and excellent toughness in order to ensure broken face transition temperature (vTrs) as can be known thus, solid solution Nb amount need be suppressed in below 0.005%.Be preferably below 0.004%, more preferably suppressing is below 0.003%.
And for when guaranteeing intensity stabilization, form the bainite structure of high tenacity, replace having the Nb that hardenability improves effect, need make it contain an amount of solid solution B and Cr.
Fig. 4 is the relation of expression solid solution B amount and tensile strength (TS), in the steel that only make solid solution B quantitative changeization of composition in specialized range beyond the solid solution B, measures tensile strength, has put the result in order.From then on Fig. 4, in order to reach the tensile strength more than the 570MPa, being necessary to make solid solution B amount is more than 0.0006%.Improve hardenability by increasing solid solution B amount, can reduce the growing amount of island martensite body (MA) and fully guarantee bainite structure, can further improve tensile strength.Preferably solid solution B amount is made as more than 0.0008%.
But if solid solution B amount is increased, then flexible is guaranteed difficulty.Fig. 5 is expression solid solution B amount and the relation of breaking face transition temperature (vTrs), in the steel that only make solid solution B quantitative changeization of composition in specialized range beyond the solid solution B, measures broken face transition temperature (vTrs), has put the result in order.From then on Fig. 5 is below-50 ℃ and excellent toughness in order to ensure broken face transition temperature (vTrs), solid solution B amount need be suppressed in below 0.0021%.Be preferably below 0.0017%, more preferably below 0.0013%.
And, in order fully to guarantee the bainite structure of proof strength, improve to realize high-yield strengthization and flexible, add Cr to promoting bainitic transformation, the growing amount that reduces MA is effective.In order to bring into play such effect of Cr, be necessary Cr content is made as more than 0.50%.Be preferably more than 0.7%, more preferably more than 0.8%.But if Cr is excessively contained, then because make the toughness deterioration of welding joint, so be suppressed at below 1.50%.Be preferably below 1.3%.
Steel plate of the present invention is the bainite steel plate, and containing bainite with duty cyclometer is more than 90%.Preferred bainite is counted more than 95% with space factor.Also have, the tissue as forming inevitably in external manufacturing processed at bainite contains ferrite and MA sometimes, but is preferably the least possible degree, is suppressed at below 10% in the present invention.Be preferably and be lower than 5%, more preferably be lower than 3%.
The present invention, by particularly control and control solid solution Nb amount, solid solution B amount and the Cr of above-mentioned long-width ratio measure, guarantee excellent toughness in the high intensity region more than 570MPa, and can reach low sound each to incorgruous, but, be necessary other composition of following control in order positively to bring into play this action effect.
<C：0.02～0.08％>
C is the important element that is used to guarantee intensity (TS and YS), makes it to contain promising 0.02% in the present invention at least.Be preferably more than 0.025%, more preferably more than 0.030%.But if C is excessively contained, then during the cooling after hot rolling, bainite does not generate and martensite becomes and is easy to generate, and is difficult to the toughness that obtains expecting.And when austenite phase transformation, C is partial denseization easily, and the growing amount of MA increases and improves the yield strength difficulty that becomes.Therefore C content is made as below 0.08%.Be preferably below 0.06%, more preferably below 0.05%.
<Si：0.05～0.50％>
Si suppresses the growing amount of MA and the element that improves yield strength.And also be as the useful element of reductor,, be necessary to make it to contain promising more than 0.05% in order to bring into play this effect effectively.Be preferably more than 0.07%.But if Si is excessively contained, then toughness reduces, so its upper limit is made as 0.50%.Be preferably below 0.40%, more preferably below 0.30%.
<Mn：1.0～2.5％>
Mn improves the element that hardenability helps the high strength (high TS and high YSization) of steel plate.And, also have and make the bainite granular to improve the element of flexible effect.In order to bring into play this effect effectively, Mn is contained more than 1.0%.Be preferably more than 1.4%.But if Mn content becomes excessive, then hardenability becomes too high and makes the remarkable deterioration of toughness.Therefore be made as below 2.5% in the present invention.Be preferably below 2.0%.
＜P:0.015% following (not containing 0%) 〉
Because P causes dysgenic element to toughness,, be suppressed at below 0.015% in the present invention so require to do one's utmost to reduce.Be preferably below 0.010%.
＜S:0.006% following (not containing 0%) 〉
Because can generating thick sulfide, S makes the toughness deterioration, so require to do one's utmost to reduce.Therefore be suppressed at below 0.006% in the present invention.Be preferably below 0.004%.
<Ti：0.005～0.030％>
Ti is the element that helps high-yield strengthization.Consequently, can improve the intensity (TS and YS) of steel plate.And it is still fixed solid solution N as TiN, makes solid solution B amount increase and improve hardenability, and the generation of inhibition MA is to guaranteeing the bainite structure effective elements.In addition, it also has thickization that suppresses old austenite crystal grain, prevents the effect of flexible deterioration.In order to bring into play this effect effectively, need make it to contain promising more than 0.005%.Be preferably more than 0.010%.But,, then cause flexible to reduce on the contrary, so be made as below 0.030% if making it excessive contains.Be preferably below 0.020%.
<N：0.0030～0.0080％>
N and Al and Ti chemical combination form nitride, effectively flexible are improved by the granular of organizing to play a role.In order to bring into play this effect effectively, requirement makes it to contain promising more than 0.0030%.Be preferably more than 0.0040%.But N is excessive to be contained if make, then because make welding joint toughness deterioration, so N content is suppressed at below 0.0080%.Be preferably below 0.0070%, more preferably below 0.0060%.
Contain element as mentioned above by given to this invention, the remainder composition comes down to Fe, but in steel, situation according to raw material, material, producing apparatus, as the unavoidable impurities that is brought into, much less allow the sneaking into of Al etc. below 0.070%, can described effect of the present invention not brought in the scope of disadvantageous effect, as described below, can also contain other elements energetically.
＜from by Cu:0.05～1.20%, Ni:0.05～1.20%, and the group that forms of Mo:0.03～0.50% selection more than a kind
These elements, any all is the elements that help guaranteeing intensity, Cu is by solution strengthening and precipitation strength, and to improving the element that intensity (TS and YS) plays a role effectively.In order to bring into play this effect effectively, it is promising more than 0.05% that Cu is contained.More preferably more than 0.10%.But, if making it excessive contains, then because hinder hot workability, so be preferably below 1.20%.More preferably below 1.0%.
Ni is the element that the strength and toughness of mother metal is improved simultaneously.In order to bring into play this effect effectively, preferably make it to contain promising more than 0.05%.More preferably more than 0.10%.But, if excessively contain, then because cost is increased, so preferably be suppressed at below 1.20%.More preferably below 1.0%.
Mo improves hardenability, to intensity (TS and the YS) effective elements of guaranteeing steel plate.And, containing in the lump with B by making it, the hardenability in the time of can making the cooling after rolling is controlled, thus intensity of making (TS) and flexible balance optimizing.In order to bring into play this effect, need make it to contain promising more than 0.03%.More preferably more than 0.05%, more preferably more than 0.10%.But, if making it excessive contains, then because make the toughness deterioration, so can be made as below 0.50%.More preferably below 0.40%.
＜Ca:0.0005～0.005% and/or REM:0.0003～0.003% 〉
Ca is by fixing S as CaS, and control is as the form of granulous non-metallic inclusion, and helps to make toughness to improve, and prevents the destruction from segregation portion.For such effect is given full play to, Ca is contained promisingly still, make it excessive and contain more than 0.0005% (more preferably more than 0.0010%), then not only this effect is saturated, and toughness deterioration on the contrary.Therefore, preferred Ca content is below 0.005%, more preferably below 0.004%.
Rare earth metal (abbreviating REM in this manual as) is same with above-mentioned Ca, also is as sulfide S to be fixed, and acts on the toughness that makes segregation portion effectively and improves.In order to bring into play this effect, it is promising more than 0.0003% that REM is contained.More preferably more than 0.0010%.But if making it excessive contains, then because the existence of excessive non-metallic inclusion makes the toughness deterioration on the contrary.Therefore, preferably be suppressed at below 0.003%, more preferably below 0.0025%.
In order to make steel plate of the present invention, can adopt slab basically by continuous metal cast process or ingot bar method made, by hot rolling-cooling-heat treated usual method manufacturing, but, in order to satisfy above-mentioned each prerequisite, Heating temperature when recommending hot rolling is 1000～1200 ℃, the full draught in non-recrystallization district is controlled at more than 10% but below 50%, and establishing the final rolling temperature of heat is 850 ℃, in addition, arrive the cooling till final after rolling 400 ℃ of heat, carry out air cooling or quicken cooling (3 ℃/more than the s).
At first, the Heating temperature during hot rolling is made as 1000～1200 ℃.Can because can make Nb and B solid solution, can suppress the over-drastic granular of austenite grain, so can improve hardenability by steel disc is heated to more than 1000 ℃.Consequently, can suppress the generation of MA and realize high-yield strengthization.More wish preferably to be heated to more than 1050 ℃.But, if Heating temperature surpasses 1150 ℃, then because austenite thickization of grain and toughness deterioration, so Heating temperature is made as below 1200 ℃.More preferably below 1100 ℃.
The full draught in γ (austenite) non-recrystallization district is made as more than 10% but below 50%.By controlling this draught, can make long-width ratio within the limits prescribed.Because if this draught is lower than 10%, then long-width ratio is too small, so be not preferred.More preferably the full draught in γ non-recrystallization district is more than 15%.But if this draught surpasses 50%, then long-width ratio becomes excessive, and the sound anisotropy improves, so be not preferred.More preferably the full draught in γ non-recrystallization district is below 40%.
Final rolling temperature (FRT) can be made as more than 850 ℃.This is because by being made as this can suppress long-width ratio more than temperature rising, guarantees the sound anisotropy.More preferably more than 870 ℃.On the other hand, final rolling temperature is too high, the processing deficiency in γ non-recrystallization district, and the toughness deterioration is preferably being carried out below 890 ℃ thus.
Cooling after the hot rolling, can by air cooling or 3 ℃/more than the sec, be cooled to 400 ℃ from final rolling end temp.Like this after hot rolling, by air cooling or quicken cooling, denseization of the C due to the diffusion of the C when preventing austenite phase transformation can suppress the generation of MA, as a result of is to improve yield strength.Can be more preferably 5 ℃/more than the sec, further preferably 7 ℃/cool off more than the sec.Do not need to carry out this cooled tempering, steel plate of the present invention is by non-modified and obtain.
Steel plate of the present invention, because have aforesaid high strength and high tenacity, and the sound anisotropy is little, so be suitable for the manufacturing of bridge and building structure, shipbuilding, marine structure most.Also have, steel plate of the present invention is classified as thickness of slab 10～100mm and Plate Steel.
Below, enumerate implementation column the present invention more specifically is described, still, the present invention is not subjected to the restriction of following embodiment certainly, also can be before can meeting the scope of aim described later, suitably changed and implemented, these all are contained in technical scope of the present invention.
Embodiment
The steel (remainder is Fe and unavoidable impurities) that becomes to be grouped into shown in the following table 1 with the usual method melting, is become after the slab, be heated to 1000～1200 ℃, be rolled, be cooled to 400 ℃ and obtain steel plate with the condition shown in the following table 2.In following table 2, represent the full draught in γ non-recrystallization district, final rolling temperature (FRT) respectively, from the final rolling back of finishing to 400 ℃ speed of cooling, and the thickness of slab of steel plate.
Use resulting steel plate, try to achieve long-width ratio, solid solution Nb amount, the solid solution B amount of metal structure, old austenite particle diameter, and estimate sound anisotropy, tensile properties (yield strength, tensile strength), toughness (impact characteristics) with following main points respectively.
(observation of metal structure)
Take test film from t/4 (apart from the degree of depth on the surface 1/4) position of steel plate, this test film is carried out the nital corrosion, carry out observation by light microscope (100 times of multiplying powers), try to achieve the area occupation ratio of bainite structure, in optional 3 visuals field, carry out same observation, calculate the mean value of the area occupation ratio of bainite structure.And, deduct the area occupation ratio of above-mentioned bainite structure from whole tissue (100%), and try to achieve the area occupation ratio of other tissue (ferrite and MA etc.).
As its result, under record and narrate in 2, bainite accounts for being expressed as more than 90% " B " in area occupation ratio, bainite is lower than 90% in area occupation ratio, and is expressed as " F+B " as what the ferrite of the 2nd phase generated.
(mensuration of the long-width ratio of old austenite particle diameter)
Carry out the nital corrosion, old austenite grain boundary in the thickness of slab section parallel with main rolling direction is occurred, carry out structure observation by opticmicroscope with 100 times, and measure the median size of main rolling direction and the median size of thickness of slab direction, in 3 visuals field, try to achieve its ratio (median size of the median size of main rolling direction/thickness of slab direction), with it on average as mean aspect ratio.
(solid solution Nb amount, the mensuration of solid solution B amount)
Utilize to extract the residue method with precipitate as the residue separation and Extraction, try to achieve the Nb amount and B amount that constitute this precipitate respectively,, deduct the Nb amount and B amount that constitute above-mentioned precipitate respectively from the Nb amount (total Nb amount) of steel plate and the B amount (total B amount) of steel plate, calculate solid solution Nb amount, solid solution B amount.
(tension test)
Take No. 22014 test films of JIS Z from the thickness of slab t/4 position of each steel plate, carry out tension test, measure yield strength (0.2% yield-point: σ 0.2) and tensile strength (TS) with the main points of JIS Z 2214.Then, if yield strength: 450Mpa is above and tensile strength: more than 570, then be evaluated as high strength.
(the anisotropic evaluation of sound)
Regulation according to JIS Z 3060, shear wave velocity of sound value CSL when mensuration makes the direction of vibration of shear wave consistent with main rolling direction (L direction), shear wave velocity of sound value CSC with making it when consistent with the vertical direction of L direction (C direction) tries to achieve the shear wave velocity of sound and compares CSL/CSC.Then, this velocity of sound is than being that average evaluation below 1.02 is that the sound anisotropy is little.
(shock test (flexible evaluation))
Take No. 4 test films of JIS Z 2202 from thickness of slab 1/4 position of each steel plate, carry out pendulum impact test, measure broken face transition temperature (vTrs) with the method for JIS Z 2242.Then, measuring broken face transition temperature (vTrs) is tenacity excellent for the average evaluation below-50 ℃.
These results are recorded in the table 2 in the lump.
Table 1
| The steel grade numbering | Chemical ingredients (mass%) ※ | ||||||||||||||||||
| C | Si | Mn | Al | Cr | Ti | B | N | Nb | Cu | Ni | Mo | V | Zr | Mg | Ca | REM | P | S | |
| A | 0.03 | 0.10 | 1.55 | 0.030 | 0.70 | 0.013 | 0.0019 | 0.0050 | 0.003 | - | - | - | - | - | - | - | - | 0.006 | 0.001 |
| B | 0.03 | 0.10 | 1.55 | 0.030 | 0.90 | 0.013 | 0.0019 | 0.0047 | 0.004 | - | 0.25 | 0.20 | - | - | - | - | - | 0.007 | 0.002 |
| C | 0.03 | 0.10 | 1.20 | 0.030 | 0.70 | 0.012 | 0.0018 | 0.0051 | 0.003 | 0.35 | 0.25 | - | - | - | - | - | - | 0.003 | 0.005 |
| D | 0.03 | 0.10 | 1.50 | 0.030 | 0.70 | 0.012 | 0.0020 | 0.0050 | 0.001 | 0.35 | 0.25 | 0.20 | - | - | - | - | - | 0.008 | 0.002 |
| E | 0.05 | 0.10 | 2.09 | 0.031 | 0.73 | 0.013 | 0.0021 | 0.0054 | 0.001 | - | - | - | 0.021 | - | - | - | - | 0.007 | 0.005 |
| F | 0.08 | 0.10 | 1.55 | 0.030 | 0.91 | 0.013 | 0.0018 | 0.0051 | 0.002 | - | - | 0.21 | - | - | - | - | - | 0.005 | 0.002 |
| G | 0.02 | 0.35 | 1.55 | 0.032 | 0.90 | 0.013 | 0.0018 | 0.0052 | 0.003 | - | 0.25 | 0.20 | - | - | - | 0.0021 | 0.0012 | 0.010 | 0.002 |
| H | 0.03 | 0.10 | 1.75 | 0.033 | 0.61 | 0.014 | 0.0020 | 0.0050 | 0.002 | - | 0.22 | - | - | - | 0.0023 | - | - | 0.007 | 0.003 |
| I | 0.03 | 0.10 | 1.55 | 0.038 | 0.91 | 0.013 | 0.0018 | 0.0053 | 0.005 | - | - | 0.21 | - | 0.0031 | - | 0.0016 | - | 0.009 | 0.002 |
| J | 0.09 | 0.10 | 1.40 | 0.025 | 0.72 | 0.013 | 0.0018 | 0.0048 | 0.002 | - | - | 0.11 | - | - | - | - | 0.0019 | 0.005 | 0.002 |
| K | 0.06 | 0.31 | 1.91 | 0.030 | 0.03 | 0.013 | 0.0018 | 0.0046 | 0.002 | - | - | 0.31 | - | - | 0.0019 | - | - | 0.006 | 0.004 |
| L | 0.04 | 0.10 | 1.63 | 0.033 | 0.90 | 0.013 | 0.0018 | 0.0055 | 0.016 | - | - | 0.12 | 0.025 | 0.0023 | - | - | - | 0.008 | 0.002 |
| M | 0.03 | 0.10 | 1.55 | 0.031 | 0.91 | 0.003 | 0.0018 | 0.0058 | 0.002 | - | 0.13 | 0.21 | - | - | - | - | - | 0.011 | 0.006 |
| N | 0.03 | 0.10 | 1.55 | 0.030 | 0.72 | 0.013 | 0.0004 | 0.0052 | 0.002 | - | - | 0.20 | - | - | - | 0.0021 | - | 0.004 | 0.005 |
| O | 0.03 | 0.55 | 1.55 | 0.030 | 0.91 | 0.013 | 0.0018 | 0.0051 | 0.002 | - | - | 0.21 | - | - | - | - | - | 0.003 | 0.002 |
| P | 0.03 | 0.10 | 1.56 | 0.030 | 0.75 | 0.014 | 0.0036 | 0.0052 | 0.002 | - | - | - | - | - | - | - | - | 0.007 | 0.002 |
The ※ remainder is iron and unavoidable impurities
Table 2
| Experiment No. | The steel grade numbering | Thickness of slab | Full draught in γ non-recrystallization district | FRT | Speed of cooling | Solid solution Nb | Solid solution B | Tensile properties | Impact characteristics | The sound anisotropy | Tissue | The mean aspect ratio of old γ particle diameter | |
| YS | TS | vTrs | |||||||||||
| mm | ％ | ℃ | ℃/s | ％ | ％ | MPa | MPa | ℃ | |||||
| 1 | A | 25 | 30 | 880 | 48 | 0.002 | 0.0016 | 571 | 683 | -70 | 1.011 | B | 3.1 |
| 2 | A | 50 | 20 | 850 | 5 | 0.002 | 0.0016 | 473 | 623 | -80 | 1.014 | B | 3.9 |
| 3 | B | 25 | 30 | 880 | 2 | 0.003 | 0.0016 | 551 | 668 | -75 | 1.004 | B | 1.9 |
| 4 | | 20 | 30 | 880 | 55 | 0.002 | 0.0014 | 587 | 660 | -60 | 1.008 | B | 2.6 |
| 5 | | 50 | 20 | 850 | 12 | 0.000 | 0.0016 | 605 | 703 | -90 | 1.018 | B | 4.9 |
| 6 | E | 25 | 30 | 880 | 48 | 0.000 | 0.0016 | 595 | 692 | -85 | 1.015 | B | 4.3 |
| 7 | | 80 | 15 | 850 | 6 | 0.001 | 0.0015 | 517 | 631 | -60 | 1.013 | B | 4.1 |
| 8 | G | 25 | 30 | 880 | 48 | 0.002 | 0.0015 | 607 | 710 | -120 | 1.009 | B | 3.2 |
| 9 | H | 25 | 30 | 880 | 48 | 0.001 | 0.0016 | 556 | 683 | -90 | 1. 016 | B | 4.4 |
| 10 | I | 25 | 30 | 880 | 48 | 0.004 | 0.0014 | 551 | 681 | -100 | 1.010 | B | 3.6 |
| 11 | A | 25 | 75 | 790 | 48 | 0.002 | 0.0016 | 551 | 648 | -90 | 1.031 | B | 12.1 |
| 12 | A | 80 | 5 | 880 | 6 | 0.002 | 0.0016 | 507 | 612 | -40 | 1.004 | B | 1.4 |
| 13 | J | 25 | 30 | 880 | 48 | 0.001 | 0.0016 | 592 | 697 | -5 | 1.011 | B | 2.5 |
| 14 | K | 25 | 30 | 880 | 48 | 0.001 | 0.0016 | 432 | 586 | -20 | 1.010 | F+B | 3.1 |
| 15 | L | 25 | 70 | 880 | 48 | 0.013 | 0.0014 | 463 | 634 | -15 | 1.029 | B | 11.2 |
| 16 | M | 25 | 30 | 880 | 48 | 0.001 | 0.0006 | 441 | 607 | -15 | 1.002 | F+B | 1.9 |
| 17 | N | 25 | 30 | 880 | 48 | 0.001 | 0.0004 | 379 | 498 | -120 | 1.005 | F+B | 2.3 |
| 18 | O | 25 | 30 | 880 | 48 | 0.001 | 0.0015 | 585 | 679 | -25 | 1.008 | B | 2.9 |
| 19 | P | 25 | 30 | 880 | 48 | 0.001 | 0.0034 | 593 | 698 | -25 | 1.006 | B | 2.5 |
Can do following investigation (also have, following No. represents the experiment No. in the table 2) by table 1,2.That is, because the prerequisite of the present invention's regulation is satisfied in No.1～10, so the sound anisotropy is little, and anti-characteristic and the tenacity excellent opened.
With respect to this, because the prerequisite of the discontented unabridged version invention in No.11～19 regulation, so anti-property, toughness (impact characteristics), the anisotropic at least some meetings of sound have problems.That is, the one-tenth that No.11 satisfies the present invention's regulation is grouped into, still because not with the condition manufacturing of recommendation, so long-width ratio becomes greatly, it is big that the sound anisotropy becomes.And No.12 is because long-width ratio is too small, so form the result of toughness deterioration.
No.13 is because C content is too much, so cause the result of toughness deterioration.No.14 counts more than 90% with space factor so can't guarantee bainite because Cr contains quantity not sufficient, causes YS low, the result of toughness deterioration.No.15 because solid solution Nb amount for excessive, so cause long-width ratio to uprise, thereby the sound anisotropy uprises, and the also result of deterioration on the contrary of toughness.
No.16 counts more than 90% with space factor so can't guarantee bainite because Ti contains quantity not sufficient, causes yield strength to reduce, and the result of toughness deterioration.
No.17 counts more than 90% with space factor so can't guarantee bainite because hold the B quantity not sufficient admittedly, can not guarantee intensity.
No.18 is because Si content is excessive, so cause the result of toughness deterioration.And No.19 is because solid solution B amount is excessive, so cause the result of toughness deterioration.
Claims (3)
1, a kind of steel plate is characterized in that: in quality %, contain
C：0.02～0.08％，
Si：0.05～0.50％，
Mn：1.0～2.5％，
Below the P:0.015%, but do not contain 0%,
Below the S:0.006%, but do not contain 0%,
Cr：0.50～1.50％，
Ti：0.005～0.030％，
N：0.0030～0.0080％，
Solid solution Nb:0.005% is following and contain 0%,
Solid solution B:0.0006～0.0021%;
Bainite contains more than 90% with duty cyclometer;
The mean aspect ratio of the old austenite crystallization particle diameter in the thickness of slab section parallel with main rolling direction, promptly the median size of the median size of main rolling direction/thickness of slab direction is to surpass 1.8, but below 5.3;
Tensile strength is more than the 570MPa.
2, according to the steel plate of claim 1 record, it is characterized in that,,, also contain from by optional more than a kind the following group who forms in quality % as other element:
Cu：0.05～1.20％，
Ni:0.05～1.20%, and
Mo：0.03～0.50％。
3, according to the steel plate of claim 1 record, it is characterized in that,,, also contain Ca:0.0005～0.005% and/or REM:0.0003～0.003% in quality % as other element.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2005104705A JP4868762B2 (en) | 2005-03-31 | 2005-03-31 | High-strength, high-toughness bainite non-tempered steel sheet with small acoustic anisotropy |
| JP2005104705 | 2005-03-31 |
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| CN104711489A (en) * | 2015-03-03 | 2015-06-17 | 山东钢铁股份有限公司 | High ductility steel for semifocal chord pipe for spud leg and manufacturing method of high ductility steel |
| CN112342458A (en) * | 2020-09-01 | 2021-02-09 | 南京钢铁股份有限公司 | Low-yield-ratio stress corrosion cracking resistant high-strength steel and preparation method thereof |
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| JP2012219297A (en) * | 2011-04-06 | 2012-11-12 | Kobe Steel Ltd | Thick steel plate |
| CN109295389B (en) * | 2018-11-13 | 2020-09-01 | 江西理工大学 | Nano bainite steel with rapid phase change and preparation method thereof |
| WO2022045353A1 (en) * | 2020-08-31 | 2022-03-03 | 日本製鉄株式会社 | Steel sheet and method for manufacturing same |
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| JPH0956042A (en) * | 1995-08-11 | 1997-02-25 | Takaoka Electric Mfg Co Ltd | Wire lead-in unit of housing for electric machine |
| JP3812108B2 (en) * | 1997-12-12 | 2006-08-23 | 住友金属工業株式会社 | High-strength steel with excellent center characteristics and method for producing the same |
| JP3602396B2 (en) * | 2000-02-15 | 2004-12-15 | 株式会社神戸製鋼所 | Low yield ratio high strength steel sheet with excellent weldability |
| JP3734692B2 (en) * | 2000-08-01 | 2006-01-11 | 株式会社神戸製鋼所 | Non-refining type low yield ratio high tensile strength steel sheet with low acoustic anisotropy and excellent weldability |
| JP3736320B2 (en) * | 2000-09-11 | 2006-01-18 | Ｊｆｅスチール株式会社 | Abrasion-resistant steel with excellent toughness and delayed fracture resistance and method for producing the same |
| JP4220871B2 (en) * | 2003-03-19 | 2009-02-04 | 株式会社神戸製鋼所 | High-tensile steel plate and manufacturing method thereof |
| JP4025263B2 (en) * | 2003-07-17 | 2007-12-19 | 株式会社神戸製鋼所 | Low yield ratio high strength steel sheet with excellent gas cut crack resistance and high heat input weld toughness and low acoustic anisotropy |
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| CN104711489A (en) * | 2015-03-03 | 2015-06-17 | 山东钢铁股份有限公司 | High ductility steel for semifocal chord pipe for spud leg and manufacturing method of high ductility steel |
| CN112342458A (en) * | 2020-09-01 | 2021-02-09 | 南京钢铁股份有限公司 | Low-yield-ratio stress corrosion cracking resistant high-strength steel and preparation method thereof |
| CN112342458B (en) * | 2020-09-01 | 2022-01-11 | 南京钢铁股份有限公司 | Low-yield-ratio stress corrosion cracking resistant high-strength steel and preparation method thereof |
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| JP2006283126A (en) | 2006-10-19 |
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