CN105102661B - The steel plate of pole excellent in low temperature toughness - Google Patents

The steel plate of pole excellent in low temperature toughness Download PDF

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CN105102661B
CN105102661B CN201480020442.0A CN201480020442A CN105102661B CN 105102661 B CN105102661 B CN 105102661B CN 201480020442 A CN201480020442 A CN 201480020442A CN 105102661 B CN105102661 B CN 105102661B
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steel
steel plate
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CN105102661A (en
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伊庭野朗
名古秀德
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Kobe Steel Ltd
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Abstract

The steel plate of the present invention contains composition in set steel, and the content of Mn system field trash of the maximum gauge present in steel more than 0.1 μm be 0.001~0.07 mass %, and existing retained austenite body phase divides the rate satisfaction 2.0~12.0 volume % at 196 DEG C.

Description

The steel plate of pole excellent in low temperature toughness
Technical field
The present invention relates to the steel plate of pole excellent in low temperature toughness, in detail, even if be related to Ni contents reduce to 5.0~ 7.5% or so, the still good thick steel of toughness [the particularly toughness of plate width direction (C directions)] under less than -196 DEG C of extremely low temperature Plate.Though it is (representational to have storage with the above-mentioned steel plate towards liquefied natural gas (LNG) exposed to the open air under extremely low temperature below Tank, cargo ship etc.) centered on illustrate, but the steel plate of the present invention is not limited to this meaning, but can fit comprehensively For exposing the steel plate used in the purposes below -196 DEG C under this extremely low temperature to the open air.
Background technology
For the LNG tank steel plate of the storage tank of liquefied natural gas (LNG), in addition to having required high intensity, also Seek the high tenacity of tolerable -196 DEG C of extremely low temperature.Up to now, as the steel plate for such use, use and contain There is 9% or so Ni (9%Ni steel) steel plate, and in recent years, because Ni price rises, less than 9%, or even Under seldom Ni contents, the exploitation of the still excellent steel plate of pole low-temperature flexibility is pushed into.
Such as in non-patent literature 1, describe and low-temperature flexibility of the domain heat treatment to 6%Ni steel coexists on the phases of α-γ 2 Caused by influence.Record in detail as inferior：Before temper, by be applied to the phases of α-γ 2 coexist domain (Ac1~ Between Ac3) heat treatment (L processing), can bring with the 9%Ni steel that is handled by common Q-tempering it is equal more than ,- Pole low-temperature flexibility at 196 DEG C；The heat treatment in addition improves also the toughness of C directions (plate width direction) test film；These effects It is based on the presence for having substantial amounts of fine and under extremely low temperature shock loading still to keep stable retained austenite.But According to the above method, although the pole excellent in low temperature toughness of rolling direction (L directions), the extremely low temperature of plate width direction (C directions) Toughness has the tendency of poorer than L direction.In addition, the record without percentage of brittle fracture surface.
Same technology, is recorded in patent document 1 and patent document 2 with above-mentioned non-patent literature 1.Wherein, patent text Being described in offering 1 has a kind of method, and it is that austenitic grain size etc. is controlled in given area for being 4.0~10% containing Ni Steel carry out hot rolling after, be heated to Ac1~Ac3Between, the processing being then cooled off is (equivalent to described in above-mentioned non-patent literature 1 L processing), by this processing be repeated 1 times or more than 2 times after, with Ac1The method that temperature below transformation temperature is tempered.Separately Outside, being described in patent document 2 has a kind of method, and it is for being 4.0~10% containing Ni, makes the size of the AlN before hot rolling Steel below 1 μm, carry out the method with the same heat treatment of above-mentioned patent document 1 (L processing → temper).These sides Impact value (vE at -196 DEG C described in method-196), it may be possible to speculate L directions, and the above-mentioned toughness value in C directions is not It is bright.In addition, not paid attention in these methods to intensity, recorded without percentage of brittle fracture surface.
In addition, in non-patent literature 2, record and be subject to about above-mentioned L processing (two phase region Quenching Treatments) and TMCP The exploitation of the LNG tank of combination 6%Ni steel.According to the document, although the toughness for describing rolling direction (L directions) show it is high Value, but without the toughness value for describing plate width direction (C directions).
In patent document 3, description has a kind of Mg containing 0.3~10% Ni, and given amount, and given particle diameters contain Mg The excellent high tenacity high tension steel of more than oxide particle is properly dispersed, 570MPa levels toughness of welded zone.Above-mentioned special Described in sharp document 3：By the control of the oxide containing Mg, heating austenite particle diameter obtains miniaturization, mother metal and welding heat affected The toughness in portion (HAZ) improves；Therefore, it is important that O (oxygen) amounts before deoxidant element addition, and Mg and other deoxidant elements Order of addition, after adding Mg, Ti, Al simultaneously in the molten steel that soluble oxygen content is 0.001~0.02%, cast and turn into steel Base, or in Mg, Ti, Al addition, after finally adding Al, cast and turn into steel billet.In the implementation of above-mentioned patent document 3 In example, the toughness value (fracture transition temperature vTrs) for there are C directions, the good (fracture transition temperature of above-mentioned characteristic of 9%Ni steel are described VTrs≤- 196 DEG C), the above-mentioned characteristic of the Ni steel of 5% neighborhood is -140 DEG C, it is desirable to is further improved.
【Prior art literature】
【Patent document】
【Patent document 1】The clear 49-135813 publications of Japanese Laid-Open
【Patent document 2】The clear 51-13308 publications of Japanese Laid-Open
【Patent document 3】Japanese Laid-Open 2001-123245 publications
【Non-patent literature】
【Non-patent literature 1】Open country etc. is sweared, " shadow that domain heat treatment is brought to the low-temperature flexibility of 6%Ni steel coexists in the phases of α-γ 2 Ring ", iron and steel, the 59th year (1973) No. 6, p752~763
【Non-patent literature 2】Gu Gu etc., " exploitation of LNG tank 6%Ni steel ", CAMP-ISIJ, Vol.23 (2010), p1322
As described above, up to now, the pole low-temperature flexibility in the Ni steel that Ni contents are 5.0~7.5% or so at -196 DEG C Though excellent technology is suggested, the pole low-temperature flexibility in C directions is not studied fully.It is high to be particularly strongly required strength of parent Pole low-temperature flexibility under (in detail, tensile strength TS ＞ 690MPa, yield strength YS ＞ 590MPa) high intensity further carries High (the pole low-temperature flexibility under C directions improves).
In addition, in the above documents, do not studied for percentage of brittle fracture surface.Percentage of brittle fracture surface represents Charpy impact examination Test the ratio of the brittle fracture occurred during middle application load.At the position that brittle fracture occurs, steel reach what fracture was absorbed Energy significantly diminishes, and causes to be broken easy progress, therefore in pole low-temperature flexibility develops skill, not only general Charpy impact value (vE-196) raising be important condition, make percentage of brittle fracture surface for less than 10% and extremely important important document.But as above State in the high high-strength steel plate of strength of parent, meet that the technology of the above-mentioned important document of percentage of brittle fracture surface does not propose also.
The content of the invention
The present invention is formed in view of the foregoing, its object is to, there is provided a kind of high-strength steel plate, it is in Ni contents In 5.0~7.5% or so Ni steel, the pole low-temperature flexibility (the particularly pole low-temperature flexibility in C directions) at -196 DEG C can be realized It is excellent, percentage of brittle fracture surface≤10%.
The steel plate of the pole excellent in low temperature toughness of the invention of above-mentioned problem is can solve the problem that, is in terms of quality %, contains C： 0.02~0.10%, Si：Less than 0.40% (being free of 0%), Mn：0.50~2.0%, P：Less than 0.007% (being free of 0%), S： Less than 0.007% (being free of 0%), Al：0.005~0.050%, Ni：5.0~7.5%, N：Less than 0.010% (being free of 0%), Surplus is the steel plate of iron and inevitable impurity, and what it had will be intended to, and the maximum gauge being present in steel is more than 0.1 μm the content of Mn systems field trash be 0.001~0.07 mass %, also, at -196 DEG C existing retained austenite body phase point Rate is 2.0~12.0 volume %.
In the preferred embodiment of the present invention, above-mentioned steel plate, also contain Cu：Less than 1.0% (being free of 0%).
In the preferred embodiment of the present invention, above-mentioned steel plate, also contain from Cr：Less than 1.20% (be free of 0%) and Mo：At least one selected in the group that less than 1.0% (being free of 0%) is formed.
In the preferred embodiment of the present invention, above-mentioned steel plate, also contain from Ti：Less than 0.025% (being free of 0%), Nb：Less than 0.100% (being free of 0%) and V：At least one selected in the group that less than 0.50% (being free of 0%) is formed.
In the preferred embodiment of the present invention, above-mentioned steel plate, also contain B：Less than 0.0050% (being free of 0%).
In the preferred embodiment of the present invention, above-mentioned steel plate, also contain from Ca：Less than 0.0030% (being free of 0%), REM：Less than 0.0050% (being free of 0%) and Zr：At least one selected in the group that less than 0.005% (being free of 0%) is formed Kind.
In the preferred embodiment of the present invention, if existing retained austenite body phase divides rate to be V (bodies at -196 DEG C Product %), when maximum gauge more than the content of 0.1 μm of Mn systems field trash be W (quality %), the C values that are represented by V/W be 150 with On.
In accordance with the invention it is possible to provide a kind of high-strength steel plate, it is in the Ni steel that Ni contents are 5.0~7.5% or so In, even if strength of parent height (in detail, tensile strength TS ＞ 690MPa, yield strength YS ＞ 590MPa), less than -196 DEG C The pole low-temperature flexibility pole low-temperature flexibility of C directions (particularly) it is also excellent, meet that percentage of brittle fracture surface≤10% at -196 DEG C is (excellent Elect percentage of brittle fracture surface≤50% at -233 DEG C as).
Embodiment
The characteristic of the steel plate of the present invention is, in the Ni steel that Ni contents are 5.0~7.5% or so, in order to enter One step improves the pole low-temperature flexibility in C directions, and (one) divides rate control by existing retained austenite body phase at -196 DEG C (residual γ phases) System is in 2.0~12.0 volume %, and Mn system field trash of the maximum gauge more than 0.1 μm that (two) will be present in steel is (below, There is the situation for being only called Mn systems field trash.) content control in 0.001~0.07 mass %.Especially by above-mentioned (two) Mn systems field trash is suitably controlled, so as to the fixed solid solution S for deteriorating toughness, its amount is suppressed in no dysgenic model Enclose, therefore distinguish and very excellent pole low-temperature flexibility can be achieved.
Hereinafter, illustrated for reaching fact of the present invention.
The present inventors are in order to provide in the Ni steel that Ni contents are less than 7.5%, less than -196 DEG C of pole low-temperature flexibility Excellent steel plate and study repeatedly.Specifically, in the present invention, meet that the fragility at -196 DEG C of C directions is broken from offer Face rate≤10%, tensile strength TS ＞ 690MPa, yield strength YS ＞ 590MPa complete characteristic pole excellent in low temperature toughness This viewpoint of high-strength steel plate is set out, first, the method for studying the document demonstration described in prior art.
Teaching has in the above documents, in order to improve the pole low-temperature flexibility of 5%Ni steel, it is important that make to exist at -196 DEG C Retained austenite (residual γ) stabilize.Also teach in addition, if considering manufacture method, the method recommended is in steel The liquid stage, control deoxidant element addition before soluble oxygen content, in this molten steel, finally add Al and cast, and α- Domain (A coexists in the phases of γ 2c1~Ac3Between) be heat-treated after (L processing), with Ac1Temperature below transformation temperature carries out temper, Thus, pole low-temperature flexibility improves.But distinguished according to the result of study of the present inventors, according to the above method, although L directions Pole low-temperature flexibility improve, but the pole low-temperature flexibility in C directions is insufficient, it is impossible to realizes disclosed above-mentioned target Horizontal (percentage of brittle fracture surface≤10% at -196 DEG C in C directions).
Therefore further study repeatedly as a result, it was confirmed that in order to obtain the steel plate of desired pole excellent in low temperature toughness, though It is so substantially to follow above-mentioned technology, but in steel plate and its manufacture method, it is integral adds important document again.In detail Exactly distinguish, (i) in steel plate, except making the residual γ phases at -196 DEG C exist in the range of 2.0~12.0 volume % In addition, in order to suppress the thick field trash and fixed solid solution S (=reduction solid solution S amounts) that deteriorate toughness, effectively by maximum The content of Mn system field trash of the diameter more than 0.1 μm is controlled in the range of 0.001~0.07 mass %.
And also confirm that, (ii) in order to manufacture such steel plate, effectively control the molten steel stage Al addition before Soluble oxygen content (free O amounts), and after hot rolling in Ac1~Ac3Between be heat-treated (L processing) → returned in determined temperature domain Fire processing, in addition, (ii-1) also carry out molten steel stage further control, and (ii-2) rolled before heating-up temperature Control.Specifically confirm, (ii-1) in the molten steel stage, make Al add before free oxygen concentration be below 100ppm, and And 1500~1450 DEG C of cool time (t2) when casting was controlled below 300 seconds, the heating rank of (ii-2) before the rolling Section, heating-up temperature is reduced to less than 1060 DEG C effectively.
It is moreover found that (iii) in above-mentioned (i), if existing retained austenite body phase divides rate to be V (bodies at -196 DEG C Product %), when the content of Mn system field trash of the maximum gauge more than 0.1 μm is W (quality %), if the C values represented by V/W controlled Percentage of brittle fracture surface then at -233 DEG C of the more low temperature than -196 DEG C, can be also maintained at less than 50% by system more than 150 Good level, so as to complete the present invention.
In this manual, so-called " pole excellent in low temperature toughness ", it is according to the method described in the aftermentioned column of embodiment one, surveys When measuring the percentage of brittle fracture surface in the Charpy impact absorption test of C directions (plate width direction), meet the percentage of brittle fracture surface at -196 DEG C ≤ 10%.In embodiment described later, the percentage of brittle fracture surface of L directions (rolling direction) is not measured, but is based on the rule of thumb, such as The percentage of brittle fracture surface in fruit C directions is below 10%, then the percentage of brittle fracture surface in L directions is also necessarily less than 10%.
So-called in this manual " steel plate ", mean thickness substantially 6~50mm of steel plate.
In addition in the present invention, to meet tensile strength TS ＞ 690MPa, yield strength YS ＞ 590MPa high-strength thick Steel plate is object.
Hereinafter, it is described in detail for the steel plate of the present invention.
Steel plate of the invention as described above, it has the feature that, is in terms of quality %, contains C：0.02~ 0.10%th, Si：Less than 0.40% (being free of 0%), Mn：0.50~2.0%, P：Less than 0.007% (being free of 0%), S：0.007% (being free of 0%), Al below：0.005~0.050%, Ni：5.0~7.5%, N：Less than 0.010% (being free of 0%), surplus is iron With the steel plate of inevitable impurity, existing retained austenite body phase is 2.0~12.0 volume % at -196 DEG C, also, The content of Mn system field trash of the maximum gauge more than 0.1 μm is 0.001~0.07 mass %.
Illustrated firstly, for composition in steel.
C：0.02~0.10%
C is for ensuring that intensity and retained austenite are necessary elements.In order to effectively play such effect, make C amounts Lower limit be more than 0.02%.The preferred lower limit of C amounts is more than 0.03%, more preferably more than 0.04%.But if superfluous ground Addition, then the excessive rising of intensity causes pole low-temperature flexibility to reduce, therefore makes to be limited to 0.10% thereon.The preferable upper limit of C amounts For less than 0.08%, more preferably less than 0.06%.
Si：Less than 0.40% (being free of 0%)
Si is the element useful as deoxidation material.But if add superfluously, the generation of the island martensite body phase of hard It is promoted, pole low-temperature flexibility reduces, therefore makes to be limited to less than 0.40% thereon.The preferable upper limit of Si amounts is less than 0.35%, More preferably less than 0.20%.
Mn：0.50~2.0%
Mn is austenite (γ) stabilizing element, contributes to remain the increased element of γ amounts.In order to effectively play Such effect, the lower limit for making Mn amounts are 0.50%.The preferable lower limit of Mn amounts be more than 0.6%, more preferably 0.7% with On.But if add superfluously, bring temper embrittlement, it is desirable to pole low-temperature flexibility, therefore make to be limited to less than 2.0% thereon. The preferable upper limit of Mn amounts is less than 1.5%, more preferably less than 1.3%.
P：Less than 0.007% (being free of 0%)
P is impurity element the reason for forming intercrystalline cracking, in order to ensure desired pole low-temperature flexibility, makes to be limited to thereon Less than 0.007%.The preferable upper limit of P amounts is less than 0.005%.It is industrial P amounts is had for 0% although P amounts are more few better It is difficult.
S：Less than 0.007% (being free of 0%)
S is same with above-mentioned P, and impurity element the reason for composition intercrystalline cracking, in order to ensure desired extremely low Wen Ren Property, make to be limited to less than 0.007% thereon.Shown in embodiment as be described hereinafter, if S amounts are more, percentage of brittle fracture surface increase, it is impossible to realize Desired pole low-temperature flexibility (percentage of brittle fracture surface≤10% at -196 DEG C).In addition, if S amounts are excessive, it would be desirable that Mn systems be mingled with The quantitative change of thing is more, and pole low-temperature flexibility still reduces.The preferable upper limit of S amounts is less than 0.005%.Although S amounts are more few better, It is industrial S amounts is had any problem for 0%.
Al：0.005~0.050%
Al is deoxidant element.If Al content deficiency, the oxygen concentration in steel rises, and the amount of thick Al systems field trash increases Add, the control for being mingled with object amount to desired Mn systems adversely affects that (details are aftermentioned.), therefore make its lower limit for 0.005% with On.The preferable lower limit of Al amounts is more than 0.010%, more preferably more than 0.015%.But if add superfluously, Al systems The cohesion and merging of field trash are promoted, and the control that still can be mingled with object amount to desired Mn systems adversely affects, therefore makes Less than 0.050% is limited to thereon.The preferable upper limit of Al amounts is less than 0.045%, more preferably less than 0.04%.
Ni：5.0~7.5%
Ni ensure for improve pole low-temperature flexibility retained austenite (residual γ) on be necessary element.In order to effective Ground plays such effect, and the lower limit for making Ni amounts is more than 5.0%.The preferable lower limit of Ni amounts is more than 5.2%, more preferably More than 5.4%.But if add superfluously, cause the high cost of raw material, make to be limited to less than 7.5% thereon.Ni amounts it is preferred The upper limit be less than 7.0%, more preferably less than 6.5%, more preferably less than 6.0%.
N：Less than 0.010% (being free of 0%)
N reduces pole low-temperature flexibility due to strain-aging, therefore makes to be limited to less than 0.010% thereon.N amounts it is preferable The upper limit is less than 0.006%, more preferably less than 0.004%.
The steel plate of the present invention contains mentioned component as basis, and surplus is iron and inevitable impurity.
In the present invention, for the purpose of assigning higher characteristic, following selection component can be contained.
Cu：Less than 1.0% (being free of 0%)
Cu is γ stabilizing elements, contributes to remain the increased element of γ amounts.In order to effectively play such work With preferably making Cu contain more than 0.05%.But if add superfluously, cause dramatically increasing for intensity, cannot be desired Pole low-temperature flexibility effect, therefore preferably make to be limited to less than 1.0% thereon.The preferred upper limit of Cu amounts is less than 0.8%, enters one Step is preferably less than 0.7%.
From Cr：Less than 1.20% (being free of 0%) and Mo：Selected at least in the group that less than 1.0% (being free of 0%) is formed It is a kind of
Cr and Mo is that intensity improves element.These elements can be added individually, can also two kinds be used in combination.In order to effectively Above-mentioned effect is played, it is more than 0.05% preferably to make Cr amounts, and it is more than 0.01% to make Mo amounts.But if add superfluously, recruit Intensity is caused to dramatically increase, it is impossible to ensure desired pole low-temperature flexibility, therefore make the preferable upper limits of Cr amounts be less than 1.20% (more preferably less than 1.1%, more preferably less than 0.9%, be still more preferably less than 0.5%), makes the excellent of Mo amounts The upper limit of choosing is less than 1.0% (more preferably less than 0.8%, more preferably less than 0.6%).
From Ti：Less than 0.025% (being free of 0%), Nb：Less than 0.100% (being free of 0%) and V：Less than 0.50% (is free of 0%) at least one selected in the group formed
Ti, Nb and V separate out as nitride, are the elements for making intensity increase.These elements may be added individually, also may be used It is used in combination with two or more.In order to effectively play above-mentioned effect, preferably make Ti amounts more than 0.005%, Nb amounts be 0.005% with On, V amounts are more than 0.005%.But if add superfluously, cause dramatically increasing for intensity, it is impossible to ensure desired extremely low Warm toughness, therefore the preferable upper limit of Ti amounts (is more preferably less than 0.018%, more preferably for less than 0.025% Less than 0.015%) the preferable upper limit of Nb amounts, is made (to be more preferably less than 0.05%, more preferably for less than 0.100% Less than 0.02%) the preferable upper limit for, making V amounts is less than 0.50% (more preferably less than 0.3%, more preferably 0.2% Below).
B：Less than 0.0050% (being free of 0%)
B is to contribute to the element that intensity improves by improving hardenability.In order to effectively play above-mentioned effect, preferably make B amounts are more than 0.0005%.But if add superfluously, bring dramatically increasing for intensity, it is impossible to ensure desired extremely low temperature Toughness, therefore the preferable upper limit of B amounts (is more preferably less than 0.0030%, more preferably for less than 0.0050% Less than 0.0020%).
From Ca：Less than 0.0030% (being free of 0%), REM (rare earth element)：Less than 0.0050% (be free of 0%) and Zr：At least one selected in the group that less than 0.005% (being free of 0%) is formed
Ca, REM and Zr are strong deoxidant elements, and by addition, compared with only adding Si, Al situation, the oxygen in steel is dense Degree is reduced, and thick field trash is reduced.These elements may be added individually, two or more can also be used in combination.In order to effectively play Above-mentioned effect, it is more than 0.0005% preferably to make Ca amounts, and making REM amounts, (REM described below, it is individually to contain sometimes individually to contain Amount, containing it is two or more when, be its total amount.Hereinafter, it is same to be related to REM amounts.) it is more than 0.0005%, make the Zr amounts be More than 0.0005%.But if add superfluously, the thick materialization that is mingled with increases on the contrary, pole low-temperature flexibility reduces, therefore makes The preferable upper limit of Ca amounts is less than 0.0030% (more preferably less than 0.0025%), and the preferable upper limit for making REM amounts is Less than 0.0050% (more preferably less than 0.0040%), makes the preferable upper limit of Zr amounts (be more preferably for less than 0.005% Less than 0.0040%).
In this manual, so-called REM (rare earth element) is lanthanide series (in periodic table, from atomic number 57 La to the Lu of atomic number 71 15 kinds of elements), plus Sc (scandium) and Y (yttrium) groups of elements, it can be used alone or two kinds It is used in combination above.Preferable rare earth element is Ce, La.REM addition form is not particularly limited, and can be mainly to contain Ce and La Norium (such as Ce：About 70% or so, La：About 20~30% or so) form addition, or can also be with Ce, La etc. monomer addition.
More than, it is illustrated for composition in the steel of the present invention.
In addition steel plate of the invention, existing residual γ phases meet that 2.0~12.0 volume % (are preferably at -196 DEG C 4.0~12.0 volume %).
The existing residual γ at -196 DEG C, it is known to help the raising of pole low-temperature flexibility.In order to effectively play so Effect, point rate for making residual γ phases shared in existing all tissues at -196 DEG C is more than 2.0 volume %.It is but residual γ and matrix phase ratio are stayed, more soft, if residual γ amounts are superfluous, YS cannot ensure predetermined value, therefore make to be limited to 12.0 thereon Volume %.On remaining the volume fraction of γ phases, preferable lower limit is more than 4.0 volume %, and preferred lower limit is 6.0 bodies Product more than %, the preferable upper limit is below 11.5 volume %, and the preferred upper limit is below 11.0 volume %.
Further, in the steel plate of the present invention, at -196 DEG C among existing tissue, the volume fraction of γ phases is remained Control it is critically important, on other tissues beyond residual γ, then without any restriction, as generally existing group in steel plate Knit.As the tissue beyond residual γ, for example, the carbide of bainite, martensite, cementite etc. can be enumerated etc..
In addition steel plate of the invention, the content that Mn system field trash of the maximum gauge more than 0.1 μm in ground steel be present expire 0.001~0.07 mass % of foot.If with foregoing prior art contrastingly, the present invention steel plate, what it had Maximum is characterised by that the content of above-mentioned Mn systems field trash is controlled in given area.
That is, in order to which one side ensures high intensity, while improving the percentage of brittle fracture surface under extremely low temperature, it is desirable to reduce fragility can be turned into The starting point of fracture is mingled with object amount.The present inventors are conceived among field trash particularly Mn systems field trash and studied repeatedly, its As a result distinguish, if the content of Mn systems field trash of the maximum gauge being present in steel more than 0.1 μm is higher than 0.07 mass %, no It can ensure that desired percentage of brittle fracture surface (No.29,39) with reference to the table 2B of embodiment described later.On the other hand also distinguish, in Mn It is that MnS is included in field trash, but when the content of Mn systems field trash is less than 0.001 mass %, the solid solution S that toughness deteriorates is not made Fixed for Mn systems field trash, if the solid solution S quantitative changes in steel are more, still cannot ensure desired percentage of brittle fracture surface (with reference to after The table 2B for the embodiment stated No.40).The preferred content of above-mentioned Mn systems field trash is more than 0.007 mass %, 0.065 matter Measure below %, more preferably more than 0.015 mass %, below 0.06 mass %.
The measuring method of above-mentioned Mn systems field trash, it is described in detail in the column of embodiment one described later.
Here, the composition of " Mn systems field trash ", as long as being not particularly limited containing Mn.In addition, " Mn systems field trash " The species of field trash is also not particularly limited, such as Mn oxide, except that can enumerate Mn sulfide, Mn nitride, Mn Oxynitride etc. independent particle beyond, it is two or more compound compounds that can also enumerate these independent particle things, or Compound particle that these independent particles of person are combined with other elements etc..As above-mentioned compound, for example, the oxidation of Al systems can be enumerated Complex inclusion of thing and Mn systems sulfide etc..Wherein, if consolidated from more effectively playing from Mn systems field trash to solid solution S Determining effect etc. viewpoint set out, particularly preferably using MnS etc. Mn sulfide.
Further, if simply also disclosed from this viewpoint of Control and Inclusion Removal, foregoing patent document 3 similar Technology, but the direction of Control and Inclusion Removal and the present invention are far from each other.That is, in above-mentioned patent document 3, Mg is concentrated particularly on, By making containing Mg oxide particle of the size below 2 μm largely disperse, so as to suppress the thick of the austenite crystal under high temperature Change, to improve toughness, in contrast, in the present invention, be conceived to the useful Mn of the immobilization of solid solution S to deteriorating toughness, Fix and reduce the solid solution S for reducing toughness, both as the field trash of control object composition and Control and Inclusion Removal not Together.
In addition, in order to obtain more excellent pole low-temperature flexibility (specifically, in order to by -233 DEG C percentage of brittle fracture surface protect Hold the level below 50%), if the volume fraction of existing retained austenite body phase is V (volume %) at -196 DEG C, if maximum When the content of Mn system field trash of the diameter more than 0.1 μm is W (quality %), the C values for preferably representing V/W are controlled more than 150. Above-mentioned C values are more preferably more than 300, more preferably more than 1000.Further, the upper limit of above-mentioned C values, improved from above-mentioned characteristic From the viewpoint of be not particularly limited, but from above-mentioned V, above-mentioned W scope in terms of, the upper limit of C values is controlled in less than 12000.
Then, illustrated for the manufacture method of the steel plate of the present invention.
First, in order to using as one of the characteristic of the present invention, at -196 DEG C existing residual γ phases volume integral Rate (V) control is in given area, effectively after hot rolling, in Ac1~Ac3The temperature range of point heats, after holding, at 520 DEG C ~Ac1The temperature range of point carries out 10~60 minutes tempers.
In addition, in order to which content (W) control as another feature of the present invention part, thick Mn systems field trash is existed Given area, the heating-up temperature before smelt stage and rolling is effectively controlled as follows.
I.e. effectively, control in below 100ppm, will cast in molten steel stage, the free oxygen amount [O] before Al is added When 1500~1450 DEG C of cool time (t2 is the value of slab thickness t t/2 positions) control below 300 seconds.In addition, rolling Preceding heating and temperature control is effective below 1060 DEG C.
On this point, if explaining, first, in casting, Mn systems field trash is with fusing point than Mn systems field trash High other field trashes (are mainly made up of, hereinafter referred to as high-melting-point field trash Al systems field trash etc..) it is core, it is formed at height The surface of melting point inclusions.Therefore, it is necessary to control the surface area (size × quantity) of high-melting-point field trash.If high-melting-point field trash Surface area diminish, then the Mn systems field trash for being formed at the surface of the high-melting-point field trash reaches the growth limit, shared in steel Maximum gauge be mingled with object amount more than 0.1 μm of Mn systems and be higher than 0.07 mass %.It is raw in liquation among high-melting-point field trash Into Al systems field trash merged due to cohesion, its surface area easily diminishes, but passes through 1500 DEG C~1450 when controlling casting DEG C cool time, its movement is suppressed, as a result distinguishes, can suitably control the content of above-mentioned Mn systems field trash.As after State shown in embodiment, if casting when 1500 DEG C~1450 DEG C of cool time (being t2 in table 2) more than 300 seconds, due to upper Mechanism is stated, Mn systems field trash is encouraged to the composition generation growth on Al systems field trash, and finally, above-mentioned Mn systems are mingled with object amount Amount is higher than 0.07 mass %, and pole low-temperature flexibility is reduced (with reference to table 2B described later No.39).
In addition, the above-mentioned Mn systems field trash formed during casting can contain MnS, but due to the heating-up temperature before rolling, deposit One part melt and generate as toughness reduction will because solid solution S situation.In the present invention, because by before rolling Heating and temperature control is below 1060 DEG C, so the fusing of Mn systems field trash of the heating period before rolling is suppressed, and The coarsening of the old γ particle diameters of matrix will be suppressed.Its result is, it can be ensured that the Mn systems field trash of part fusing is again Size is separated out, is promoted separating out again for Mn systems field trash.When heating-up temperature before rolling is higher than 1060 DEG C, above-mentioned effect nothing Method effectively plays, and the Mn systems more than 0.1 μm are mingled with object amount and are less than 0.001 mass % (with reference to aftermentioned table 2B No.40).
In addition, in order to which above-mentioned C values (V/W) are controlled more than 150, effectively among above-mentioned manufacture method, especially Free oxygen amount [O] is controlled in below 60ppm.
Hereinafter, it is described in detail for each operation.
(on melting process)
In the present invention, Al systems field trash merges and coarsening due to condensing, and easily forms rising as brittle fracture The thick field trash of point, pays special attention to Al adding method based on this viewpoint, to avoid such thick Al systems from pressing from both sides Debris generates.
First, when the Al as deoxidation material is added in molten steel, the free oxygen amount before Al is added (soluble oxygen content, there is letter State as the situation of [O] amount.) control in below 100ppm.Generated this is because, [if O] amount be higher than 100ppm, during Al additions Inclusion size becomes big, and result is to be unable to suitable control Mn systems field trash, it is impossible to pole low-temperature flexibility desired by realization.[O] amount is got over Few better, preferably below 80ppm, more preferably below 50ppm.Further, the lower limit of [O] amount, from making, thick field trash is fine Change this viewpoint to set out without being particularly limited to.
Method as control [O] amount as described above, for example, the deoxidant element that Mn, Si are added in molten steel can be enumerated and entered The method of row deoxidation.In addition to above-mentioned element, when alternatively composition adds Ti, Ca, REM, Zr etc. deoxidation material, lead to Crossing its addition can also control [O] to measure.
In order to control Al systems field trash, it is important that [O] amount before control Al additions, Al add with other deoxidant elements Adding order, it doesn't matter.But if adding Al in the state of [O] amount is high, due to oxidation reaction, the temperature of molten steel rises, behaviour It is dangerous on work, therefore Si, Mn are added preferably before Al.In addition, Ti etc. above-mentioned selection component, preferably adds after Al addition It is added in molten steel.
Then, start to cast.Temperature range during casting is especially important substantially below 1650 DEG C, but in the present invention Be to control the cool time (t2) within the temperature range of 1500~1450 DEG C less than 300 seconds, thus distinguish, in of the invention Mn systems field trash as object obtains rightly miniaturization, it can be ensured that appropriate amount.If t2 was more than 300 seconds, with above-mentioned Al systems field trash is core, generates secondary inclusion thing plyability, and thus, the big Mn systems field trash of size largely generates, Wu Fafa Wave desired pole low-temperature flexibility (with reference to table 2B described later No.39).If from the above point of view, t2 is more short better, preferably For less than 290 seconds, more preferably less than 280 seconds.T2 lower limit is from above-mentioned viewpoint, which is set out, to be not particularly limited, if but considering real Border operation etc., then preferably approximately more than 100 seconds.
Further, in the present invention, why casting when temperature range among concentrate particularly on 1500~1450 DEG C Temperature range, it is due to that the solidification in the temperature range, casting is carried out, thickening of the composition to molten steel is carried out, so as to be to be mingled with The temperature range that the growth of thing is promoted.
In addition, above-mentioned 1500~1450 DEG C of temperature range, the temperature of slab thickness t central part (t/2) is meant.Slab Thickness substantially 150~250mm, surface temperature is compared with the temperature of central part, in about low 200~1000 DEG C or so incline To.Because the deviation of its temperature difference of surface temperature is big, the temperature of the small central part of deviation (neighborhood of thickness t × 1/2) is made For object.The temperature of the central part of slab thickness, thermocouple can be inserted in mold and measured.
In the present invention, the cool time (t2) within the temperature range of 1500~1450 DEG C is controlled below 300 seconds i.e. Can, do not limit its means.For example, the cool time in the range of said temperature can be made to be less than 300 seconds, and for the temperature Scope is cooled down with the average cooling rate below about 0.17 DEG C/sec of constant speed, or, the cold of said temperature scope can also be made But the time is in less than 300 seconds, and is cooled down with different cooling velocities.
In addition, in the present invention, the cooling means of temperature range during for casting beyond said temperature scope does not have Any restriction, usual way (air cooling or water cooling) can be used.
After being cast as described so, heat and hot rolling, heat supply are handled.
In the present invention, by the heating and temperature control before hot rolling below 1080 DEG C.Thereby, it is possible to by Mn systems field trash Content is controlled in appropriate scope.If the heating-up temperature before hot rolling is higher than 1080 DEG C, the content of Mn systems field trash is reduced, and is obtained not To desired pole low-temperature flexibility (with reference to aftermentioned table 2B No.40).
Above-mentioned heating-up temperature is preferably less than 1070 DEG C, more preferably less than 1060 DEG C.The lower limit of above-mentioned heating-up temperature, if Consider to cause rolling temperature to reduce due to heating-up temperature low temperature, rolling load becomes big, and productivity ratio reduces etc., then it is preferably More than 900 DEG C, more preferably more than 950 DEG C.
The heat time in above-mentioned heating-up temperature section, preferably substantially 0.5~5 hours.If the above-mentioned heat time is less than 0.5 hour, then the problem of presence can not be heated to slab center etc..On the other hand, if the above-mentioned heat time was more than 5 hours, Productivity ratio reduces.Consider these, then more preferably more than 0.75 hour, less than 4 hours.
Then hot rolling is carried out.Hot-rolled process is not particularly limited, can be in a manner of it can obtain set thickness of slab, using usual Method used, adjust (finish to gauge) temperature and drafts etc..
After hot rolling, A is heated toc1~Ac3The temperature range (TL) of point, after holding, carry out water cooling.The processing equivalent to L processing described in foregoing prior art, thereby, it is possible to the residual γ for ensuring to be stabilized at -196 DEG C in the scope of given amount.
In detail, it is heated to Ac1~Ac3Two phase regions [ferrite (α)-γ] temperature (TL) of point.By being heated to this Temperature range, Ni etc. alloying element concentrate in the γ phases of generation, can obtain at room temperature with residual existing for metastable state Metastable γ phases.Less than Ac1Put or higher than Ac3During point, result is can not fully to ensure the residual γ phases at -196 DEG C.Preferably Substantially 660~710 DEG C of heating-up temperature.
Heat time (retention time, tL) at a temperature of above-mentioned two phase region, preferably approximately 10~50 points.Less than 10 minutes When, concentration of the alloying element to γ phases is not carried out fully, and on the other hand, during more than 50 minutes, α phases are annealed, intensity decreases.It is preferred that Heat time the upper limit be 30 minutes.
In addition, by making the above-mentioned heat time be more than 15 minutes, it can be ensured that the volume integral of the residual γ phases at -196 DEG C Rate is more than 4.0 volume %, thus, will can ensure that the percentage of brittle fracture surface at -233 DEG C is less than 50%, or even even in more Under low extremely low temperature, good toughness is also ensured that.Preferred lower limit when effectively playing such effect is 5.0 bodies Product more than %.Further, the upper limit of preferable heat time is (less than 30 minutes) same as described above.
Then, after water cooling to room temperature, temper is carried out.Temper is with Ac1The following temperature (T3) of point carries out 10~60 Minute (t3).Thus, when tempering, C is concentrated in the metastable γ of residual, remains the stability increase of metastable γ phases, therefore can Obtain the residual γ phases being also stabilized at -196 DEG C.Temperature T3 is higher than Ac1Point, or tempering time t3 are less than 10 During minute, C is not carried out fully to the concentration remained in metastable γ phases, it is impossible to the residual γ amounts [ginseng at -196 DEG C desired by ensuring According to table 2B described later No.26 (example high T3)].On the other hand, if tempering time t3 was more than 60 minutes, at -196 DEG C Remain the superfluous generation of γ phases, it is impossible to ensure set intensity [with reference to table 2B described later No.27 (example that t3 grows)].
Further, temperature T3 lower limit, is not particularly limited from the above point of view, if but considering to sufficiently promote in steel The diffusion of element, reduce dislocation density etc., then preferably approximately more than 400 DEG C.
Preferable temper condition is temperature T3：570~620 DEG C, tempering time t3：More than 15 minutes, 45 points (more preferably less than 35 points, more preferably less than 25 minutes) below.
After carrying out temper as described above, room temperature is cooled to.Cooling means is not particularly limited, air cooling or water cooling With.
In this manual, Ac1Point and Ac3Point, (" the modern metallography material 4 iron steel of volume of lecture are calculated based on following formula Material ", from the metallography meeting of Japan of civic organization).
Ac1Point=723-10.7 × [Mn] -16.9 × [Ni]+29.1 × [Si]+16.9 × [Cr]+290 × [As]+6.38 ×[W]
Ac3Point=910-203 × [C]1/2-15.2×[Ni]+44.7×[Si]+104×[V]+31.5×[Mo]+13.1× [W]
In above-mentioned formula, [] means the concentration (quality %) of the alloying element in steel.Further, in the present invention, because As and W is not contained as composition in steel, so in above formula, [As] and [W] calculates as 0%.
【Embodiment】
Hereinafter, enumerate embodiment and further illustrate the present invention, but the present invention is not limited by following embodiments, can accorded with Implementation may also be changed before conjunction in the range of objective described later, these are all contained in the technical scope of the present invention.
Embodiment 1
Using vacuum melting furnace (150kgVIF), with the melting condition shown in table 2, the composition composition shown in melting table 1 is (remaining Amount：Iron and inevitable impurity, unit are quality %) for examination steel, after casting, pass through hot forging, make 150mm × 150mm × 600mm steel ingot.In the present embodiment, as REM, the norium containing Ce about 50%, La about 25% is used.Separately Outside, the order of addition of deoxidant element, it is Si, Mn (adding simultaneously) → Al during without selection component；On the other hand, containing Ti, It is Si, Mn (adding simultaneously) → Al → Ti → REM, Zr, Ca (while addition) when REM, Zr, Ca selection component.In addition, table 2 In, [O] is the soluble oxygen content (ppm) before Al additions, and t2 is 1500~1450 DEG C of cool time (second) when casting.1500~ 1450 DEG C of cooling, by air cooling or water cooling, it is controlled by a manner of reaching above-mentioned cool time.
Then, by above-mentioned steel ingot, after " heating-up temperature before rolling " heating described in table 2, with more than 830 DEG C temperature Degree is rolled down to thickness of slab 75mm, and water cooling is carried out after being rolled with final 780 DEG C of rolling temperature, thus obtains thickness of slab 25mm thickness Steel plate.By so obtained steel plate, after being heated to the temperature shown in table 2 (in table 2, TL), carry out heating in 5~60 minutes and keep After (with reference to the tL of table 2), water cooling to room temperature.Next, temper (T3=temperatures, t3=tempering are carried out as shown in table 2 Time) after, air cooling or water cooling are carried out until room temperature.
For so obtained steel plate, as follows, Mn system field trash of the evaluation maximum gauge more than 0.1 μm contains Amount (in table 2 describe be " W "), at -196 DEG C existing residual γ phases volume fraction (description is " V " in table 2), tensile characteristics (tensile strength TS, yield strength YS), pole low-temperature flexibility (percentage of brittle fracture surface in the C directions at -196 DEG C or -233 DEG C).
(1) measurement of the content of the super Mn systems field trash of 0.1 μm of maximum gauge
The content of Mn system field trash of the maximum gauge present in steel plate more than 0.1 μm, is tried to achieve in the following way：From upper State the t/4 positions (t of steel plate：Thickness of slab) on, extract number of cross-sections mm immediately below the section of the surplus material after pendulum test (10mm × 10mm × 5mm or so) sample, by electroextraction (iodo- methanol method) measurement form compound compound type Mn it is dense Spend (insol.Mn amounts).
Specifically, sample is immersed in AA systems electrolyte (acetylacetone,2,4-pentanedione-tetramethyl-ammonium chloride-methanol solution), with 20mA/cm2Following condition carries out constant-current electrolysis.After electrolysis terminates, sample is moved into added with 14% iodine methanol solution In the beaker of (dissolving 140g iodine, the solution as 1L with anhydrous methanol), with magnetic stirrer, for carrying for sample surface Thing is taken to carry out ultrasonic wave stripping.Then, for resulting ultrasonic wave stripper, and electrolyte after foregoing electrolysis is inhaled Filter, is trapped using barrier filter.Barrier filter uses the molecular filter (0.1 μm of aperture) that material is makrolon.Resistance will be remained in The residue (precipitate) kept off on filter disc, is moved into platinum crucible together with barrier filter, and ash is allowed to gas burner heating Change.Then, flux (being mixed with sodium carbonate and sodium tetraborate) is added in platinum crucible, is heated, made residual with gas burner once again Slag melts.Then, added into the fused mass after sour (hydrochloric acid) and water dissolved, move into volumetric flask, addition water and constant volume (50mL), using it as analysis liquid, the Mn amounts in analysis liquid are measured using ICP apparatus for analyzing luminosity.So measure by ICP method The Mn amounts (g) of the compound type detected are used as (1).
Next, according to the Mn amounts (1) for the compound type obtained by ICP method measured in the above described manner, before electrolysis The difference (2) of the weight (g) of sample afterwards, based on following formula, contained compound type Mn containing ratio in calculating sample.
Contained compound type Mn containing ratio (%) in sample
The weight difference (2) × 100 of the front and rear sample of the Mn amounts (1) of=compound type obtained by ICP method/electrolysis
(2) at -196 DEG C the amount (volume fraction) of existing residual γ phases measurement
From the t/4 positions of each steel plate, 10mm × 10mm × 55mm test film is extracted, (- 196 DEG C) keep with liquid nitrogen temperature After 5 minutes, X-ray diffraction measurement is carried out with the two-dimentional zone X ray detecting diffraction instrument (RINT-RAPIDII) of リ ガ Network society.Connect , for (110) of ferritic phase, (200), (211), (220) each lattice plane peak value, and residual γ phases (111), (200), (220), (311) each lattice plane peak value, integrated intensity ratio based on each peak value, calculate residual γ phases respectively (111), (200), (220), the volume fraction of (311), try to achieve its average value, as " residual γ volume fraction ".
(3) measurement of tensile characteristics (tensile strength TS, yield strength YS)
From the t/4 positions of each steel plate, JIS Z2241 No. 4 test films are abreast extracted with C directions, with ZIS Z2241 institutes The method stated carries out tension test, measures tensile strength TS and yield strength YS.In the present embodiment, TS ＞ 690MPa, YS ＞ 590MPa to be evaluated as strength of parent excellent.
(4) measurement of pole low-temperature flexibility (percentage of brittle fracture surface in C directions)
The measurement of percentage of brittle fracture surface at -196 DEG C of (4-1)
From the t/4 positions (t of each steel plate：Thickness of slab) and W/4 positions (W：Plate is wide), and t/4 positions and with W/2 positions, with C Pendulum impact test piece (JIS Z 2242 V notch test sheets) 3 is abreast extracted in direction, with the side described in JIS Z2242 Method, the percentage of brittle fracture surface (%) at -196 DEG C of measurement, calculates respective average value.Then, two average values so calculated it In, using the average value of (that is, percentage of brittle fracture surface big) side of characteristic difference, the value is below 10%, in the present embodiment It is evaluated as pole excellent in low temperature toughness.
The measurement of percentage of brittle fracture surface at -233 DEG C of (4-2)
Again for the data (being example of the present invention) of a part, the percentage of brittle fracture surface at -233 DEG C of evaluation.
Specifically, from t/4 positions and W/4 positions extraction test film 3, implement in the method described below at -233 DEG C Pendulum impact test, evaluate the average value of percentage of brittle fracture surface.In the present embodiment, above-mentioned percentage of brittle fracture surface≤50%, evaluation It is excellent for the percentage of brittle fracture surface at -233 DEG C.
" gases at high pressure ", volume 24 page 181, " the extremely low temperature impact test of austenite stainless steel cast steel "
These results describe in table 2 in the lump.In order to refer to, A is also described in the lump in Tables 1 and 2c1Point and Ac3Point.
【Table 1A】
【Table 1B】
【Table 2A】
【Table 2B】
It can be investigated as follows by table 2.
First, table 2A No.1~22 are the important document for all meeting the present invention using the steel of table 1A No.1~22 respectively Example.As set forth in table 2, according to the invention described above example, using the teaching of the invention it is possible to provide even if strength of parent is high, the extremely low temperature at -196 DEG C Toughness (in detail, average value≤10% of the percentage of brittle fracture surface in C directions) also excellent steel plate.
In contrast, table 2B No.23~42, because being unsatisfactory for composition or preferable manufacture in steel specified in the present invention At least one party of condition, so be the comparative example for being unsatisfactory for the important document of the present invention, cannot desired characteristic.
Specifically, No.23 is the No.23 for the table 1B for having used C amounts more example, and percentage of brittle fracture surface increases, it is impossible to real Existing desired pole low-temperature flexibility.
No.24 is the No.24 for the table 1B for having used P amounts more example, and percentage of brittle fracture surface increases, it is impossible to pole desired by realization Low-temperature flexibility.
No.25 uses the more table 1B of Si amounts No.25, also, is heated with the temperature higher than two phase region temperature (TL), Therefore it is the example for remaining γ amounts deficiency.As a result, percentage of brittle fracture surface also increases, it is impossible to pole low-temperature flexibility desired by realization.
No.26 has used the No.26 of the table 1B of the important document of the composition satisfaction present invention in steel, but temperature (T3) is high, because This is the example for remaining γ amounts deficiency.As a result, percentage of brittle fracture surface also increases, it is impossible to pole low-temperature flexibility desired by realization.
No.27 has used the No.27 of the table 1B of the important document of the composition satisfaction present invention in steel, but tempering time (t3) is long, because This residual γ amount increase, it is impossible to ensure desired strength of parent.
No.28 is the example for remaining γ amounts deficiency because having used the few table 1B of Mn amounts No.28.As a result, Percentage of brittle fracture surface also increases, it is impossible to pole low-temperature flexibility desired by realization.
No.29 is the No.29 for the table 1B for having used S amounts more example.Therefore, although by the heating and temperature control before hot rolling At currently preferred scope (less than 1060 DEG C), but due to the amount increase of Mn systems field trash, percentage of brittle fracture surface is caused to increase, no Pole low-temperature flexibility desired by realizing.
No.30 is because used C amounts few, and Al amounts are more, the few table 1B of Ni amounts No.30, so being residual γ amount deficiencies Example.As a result, percentage of brittle fracture surface also increases, it is impossible to pole low-temperature flexibility desired by realization.In addition TS and YS are also reduced.
No.31 has used Al amounts few, the more table 1B of N amounts No.31, therefore percentage of brittle fracture surface increase, it is impossible to realizes and wishes Pole low-temperature flexibility.
For No.32 because having used the Cu amounts of alternatively composition and the more table 1B of Ca amounts No.32, intensity is significant Rising causes percentage of brittle fracture surface to increase, it is impossible to pole low-temperature flexibility desired by realization.
No.33 has used the No.33 of the table 1B more than the Cr amounts and Zr amounts of alternatively composition, therefore the notable rising of intensity Percentage of brittle fracture surface is caused to increase, it is impossible to pole low-temperature flexibility desired by realization.
No.34 has used the No.34 of the table 1B more than the Nb amounts and REM amounts of alternatively composition, therefore percentage of brittle fracture surface increases Add, it is impossible to pole low-temperature flexibility desired by realization.
No.35 is because used the more table 1B of the Mo amounts of alternatively composition No.35, percentage of brittle fracture surface increase, Desired pole low-temperature flexibility can not be realized.
No.36 is because used the more table 1B of the Ti amounts of alternatively composition No.36, percentage of brittle fracture surface increase, Desired pole low-temperature flexibility can not be realized.
No.37 because having used the more table 1B of the V amounts of alternatively composition No.37, lead by the notable rising of intensity Cause percentage of brittle fracture surface increase, it is impossible to pole low-temperature flexibility desired by realization.
No.38 has used the more table 1B of the B amounts of alternatively composition No.38, therefore percentage of brittle fracture surface increase, it is impossible to real Existing desired pole low-temperature flexibility.
No.39 although used composition in steel meet the present invention important document table 1B No.39, but 1500 when casting~ 1450 DEG C of cool time (t2) is long, it is desirable to Mn systems field trash amount it is more.As a result, percentage of brittle fracture surface also increases, Desired pole low-temperature flexibility can not be realized.
No.40 be used composition in steel meet the present invention important document table 1B No.40, but the heating-up temperature before rolling High example.Therefore, the content of Mn systems field trash is less than 0.001 mass %, percentage of brittle fracture surface increase, it is impossible to pole desired by realization Low-temperature flexibility.Further, in table 2B, the W values (content of Mn systems field trash) on No.40 " V/W " one column are less than 0.001 mass %, Therefore it can not be calculated, be empty column.
No.41 has used the No.41 of the table 1B of the important document of the composition satisfaction present invention in steel, but with less than two phase region temperature (TL) temperature is heated, therefore is the example for remaining γ amounts deficiency.As a result, percentage of brittle fracture surface also increases, it is impossible to real Existing desired pole low-temperature flexibility.
No.42 has used the No.42 of the table 1B of the important document of the composition satisfaction present invention in steel, but because more than in two phase region temperature Degree under heat time (tL) and heated, so intensity decreases.
In addition, among table 2A example of the present invention (No.1~22), except the invention described above example of No.4,10,14,15,17, Because the free oxygen amount [O] before Al is added controls is adjusted to more than 150 in below 60ppm, C values, so crisp at -233 DEG C Property section rate is also good.
In detail and illustrate the present invention with reference to specific embodiment, but do not depart from the spirit and scope of the present invention and can It is subject to various changes and modifications, this will be apparent that for practitioner.
The application is based on Japanese patent application (patent application 2013-086852) filed in 17 days April in 2013, its content Reference herein is simultaneously quoted.
【Industrial applicability】
The steel plate of the present invention, such as storage tank as LNG and cargo ship are with useful.

Claims (3)

1. a kind of steel plate of pole excellent in low temperature toughness, it is characterised in that the steel plate is contained in terms of quality %
C：0.02~0.10%,
Si：Less than 0.40% but without 0%,
Mn：0.50~2.0%,
P：Less than 0.007% but without 0%,
S：Less than 0.007% but without 0%,
Al：0.005~0.050%,
Ni：5.0~7.5%,
N：Less than 0.010% but without 0%,
Surplus is iron and inevitable impurity,
The content of Mn system field trash of the maximum gauge present in steel more than 0.1 μm is 0.001~0.07 mass %, and
Existing retained austenite body phase divides the rate to be 2.0~12.0 volume % at -196 DEG C,
Plate width direction is percentage of brittle fracture surface≤10% at -196 DEG C of C directions.
2. steel plate according to claim 1, wherein, also contain at least one of (a)~(e),
(a)Cu：Less than 1.0% but without 0%
(b) from Cr：Less than 1.20% but be free of 0% and Mo：Less than 1.0% but without 0% form group in select at least one Kind
(c) from Ti：Less than 0.025% but without 0%, Nb：Less than 0.100% but be free of 0% and V：Less than 0.50% but be free of At least one selected in 0% group formed
(d)B：Less than 0.0050% but without 0%
(e) from Ca：Less than 0.0030% but without 0%, REM：Less than 0.0050% but be free of 0% and Zr：Less than 0.005% but Without at least one selected in 0% group formed.
3. steel plate according to claim 1 or 2, wherein, if at -196 DEG C existing retained austenite body phase divide rate with Volume % is calculated as V, when the content of Mn system field trash of the maximum gauge more than 0.1 μm is calculated as W with quality %, by the C values of V/W expressions For more than 150.
CN201480020442.0A 2013-04-17 2014-04-08 The steel plate of pole excellent in low temperature toughness Expired - Fee Related CN105102661B (en)

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PCT/JP2014/060200 WO2014171368A1 (en) 2013-04-17 2014-04-08 Thick steel plate having excellent ultralow-temperature toughness

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Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6196929B2 (en) * 2014-04-08 2017-09-13 株式会社神戸製鋼所 Thick steel plate with excellent HAZ toughness at cryogenic temperatures
JP6206423B2 (en) * 2015-01-22 2017-10-04 Ｊｆｅスチール株式会社 High strength stainless steel plate excellent in low temperature toughness and method for producing the same
JP2017115239A (en) * 2015-12-18 2017-06-29 株式会社神戸製鋼所 Thick steel sheet excellent in ultra low temperature toughness
CN105543694B (en) * 2015-12-29 2017-12-29 东北大学 A kind of preparation method of LNG tank 7Ni steel plates
JP6760056B2 (en) * 2016-12-28 2020-09-23 日本製鉄株式会社 Ni steel for liquid hydrogen
JP6760055B2 (en) * 2016-12-28 2020-09-23 日本製鉄株式会社 Ni steel for liquid hydrogen
CN109554608B (en) * 2017-09-25 2022-03-15 宝钢德盛不锈钢有限公司 Austenitic stainless steel with excellent ultralow temperature performance and manufacturing method thereof
JP6852805B2 (en) 2017-10-26 2021-03-31 日本製鉄株式会社 Nickel-containing steel for low temperature
EP3702486B1 (en) 2017-10-26 2023-03-01 Nippon Steel Corporation Nickel-containing steel for low temperature
EP3702485B1 (en) 2017-10-26 2021-12-22 Nippon Steel Corporation Nickel-containing steel for low temperature
JP6852807B2 (en) * 2017-10-26 2021-03-31 日本製鉄株式会社 Nickel-containing steel for low temperature
JP6933096B2 (en) * 2017-11-10 2021-09-08 日本製鉄株式会社 Nickel steel for high pressure hydrogen
RU2686758C1 (en) * 2018-04-02 2019-04-30 Публичное акционерное общество "Северсталь" (ПАО "Северсталь") Structural cryogenic steel and method of its production
CN112779472B (en) * 2020-12-28 2022-01-07 东北大学 1GPa grade steel plate with excellent low-temperature toughness for ocean engineering and preparation method thereof
CN113564474A (en) * 2021-07-26 2021-10-29 莱芜钢铁集团银山型钢有限公司 Steel plate with yield strength not less than 550MPa and low yield ratio for large-scale petroleum storage tank and production method thereof
CN116377343A (en) * 2022-12-14 2023-07-04 鞍钢股份有限公司 Marine engineering steel plate serving in polar region marine environment and manufacturing method thereof

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5512083B2 (en) 1973-05-04 1980-03-29
JPS5113308A (en) 1974-07-24 1976-02-02 Nippon Steel Corp TEIONYOKYOJINKOOYOBISONO NETSUSHORIHOHO
JPS61127815A (en) * 1984-11-26 1986-06-16 Nippon Steel Corp Production of high arrest steel containing ni
JPH01228643A (en) * 1988-03-09 1989-09-12 Nippon Steel Corp Method for uniformly and finely dispersing-precipitating mns in steel
JP4213833B2 (en) 1999-10-21 2009-01-21 新日本製鐵株式会社 High toughness and high strength steel with excellent weld toughness and manufacturing method thereof
JP5513254B2 (en) * 2010-05-17 2014-06-04 新日鐵住金株式会社 Low temperature steel plate and method for producing the same
KR101312211B1 (en) * 2010-07-09 2013-09-27 신닛테츠스미킨 카부시키카이샤 Ni-CONTAINING STEEL SHEET AND PROCESS FOR PRODUCING SAME
JP5432105B2 (en) * 2010-09-28 2014-03-05 株式会社神戸製鋼所 Case-hardened steel and method for producing the same
JP5741260B2 (en) * 2011-07-06 2015-07-01 新日鐵住金株式会社 Cryogenic steel material excellent in CTOD characteristics after imparting strain and method for producing the same
JP6018453B2 (en) 2012-03-09 2016-11-02 株式会社神戸製鋼所 High strength thick steel plate with excellent cryogenic toughness
JP6018454B2 (en) * 2012-04-13 2016-11-02 株式会社神戸製鋼所 High strength thick steel plate with excellent cryogenic toughness
JP5833991B2 (en) * 2012-08-23 2015-12-16 株式会社神戸製鋼所 Thick steel plate with excellent cryogenic toughness

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