CN101400813A - Steel sheet with less weld buckling deformation, and process for producing the same - Google Patents
Steel sheet with less weld buckling deformation, and process for producing the same Download PDFInfo
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- CN101400813A CN101400813A CNA2006800538179A CN200680053817A CN101400813A CN 101400813 A CN101400813 A CN 101400813A CN A2006800538179 A CNA2006800538179 A CN A2006800538179A CN 200680053817 A CN200680053817 A CN 200680053817A CN 101400813 A CN101400813 A CN 101400813A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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Abstract
A steel sheet with less welding-buckling deformation that suppresses any out-of-plane buckling deformation called ''scrawny horse deformation'' at welding sites as effectively as possible especially in weld building of a hull structure is provided through controlling of the component composition and strength characteristics of steel material, especially the balance between base material strength and strength after being affected by welding heat. When the yield stress of the steel sheet is referred to as YP0 and the yield stress of the steel sheet after application of the thermal history appearing in the description that simulates thermal influences during welding is referred to as YP1, the YP0 is 400 MPa or greater, and the ratio of YP0/YP1 is 1 or higher.
Description
Technical field
The present invention relates to a kind of steel plate that is mainly used in vessels hull constructions body etc.,, can obtain the steel plate and the method for making thereof of high structure construction though the buckling distortion during relatively thinner welding is little and do not need to weld correction after the construction.
Background technology
When building the housing department of the upper portion that constitutes the vessels hull constructions body,, on steel plate, weld fixedly stiffening web usually in order to improve structural strength.At this moment, because fusion or tissue inter-variable (α → to the reverse transformation of β) take place welded joint and the welded heat affecting zone heat during because of welding, thereby when solidifying to normal temperature, cooling (cooling) causes thermal contraction thereafter.But, owing under with the situation around the stiffening web constraint, can not carry out free shrink, thereby the suitable tension residual stress of yielding stress of generation and this weld.To cause following problems this moment, that is, because of above-mentioned residual stress makes the distortion of buckling of welding body generating plane outward, this distortion is known as " arcuation distortion " in the part at welding operation scene sometimes.
But, owing to then cause outward appearance not good if this distortion takes place, thereby buckle distortion outward and the implementation fault adds thermal recalibration etc. in order to proofread and correct this now at the housing department of hull structural member etc.But, because its correction operation trouble and need man-hour, and become the reason of claim for eot, thereby the steel plate that requires face that exploitation can not take place to cause because of such welding as far as possible to buckle and be out of shape outward.
Therefore for example patent documentation 1 publicity a kind of improving technology, it is an object with the structural steel and iron that is applied to ocean member and buildings, bridge etc., when purpose is to reduce the steel plate of low heat input welding thicker (more than the 10mm) as the Welding Angular Deformation of problem.Because this invention is subjected to the yielding stress of welding heat affected steel plate to stop welding distortion by raising, thereby particularly, as the method that is used to improve the yielding stress that is subjected to welding heat affected steel plate, it is specified by the moiety to steel plate, simultaneously the microstructure of steel product cross-sectional is reached to make more than the 30 area % at least and make trickle carbide dispersive bainite structure, yield strength is brought up to more than the 360MPa, and the yield strength of the middle temperature area more than 40 ℃ of welding distortion easily takes place in raising, when building above-mentioned steel and iron member, it is 1/2 below horizontal that the so-called angular distortion in the time of generally can be with the fillet weld welding adopted is reduced to.
In addition, in the patent documentation 2 also publicity a kind of improving technology, it is an object with the structural steel and iron that is applied to ocean member and buildings, bridge etc. equally, purpose becomes the Welding Angular Deformation of problem when being to reduce the steel plate of fillet welding thicker (more than the 10mm).This invention also is to be subjected to the yielding stress of welding heat affected steel plate to prevent welding distortion by raising, particularly, exactly as the method that is used to improve the yielding stress that is subjected to welding heat affected steel plate, it is specified by the moiety to steel plate, simultaneously microstructure is made little bainite of median size and/or martensite and ferrite and/or perlite, and micro-carboritride is existed in a large number, and improve the yield strength that the middle temperature area of welding distortion easily takes place, with the angular distortion that suppresses to cause because of fillet welding.
But, in these inventions, owing to be object and seek to suppress angular distortion by the yielding stress that improves welding heat affected position with above-mentioned thicker steel plate, thereby, then come down to diverse with its technological thought of the present invention that prevents " arch metamorphism " that rises by the temperature that suppresses the weld if be described in detail again.
Patent documentation 1:(Japan) spy opens flat 6-No. 172921 communiques
Patent documentation 2:(Japan) spy opens flat 2003-No. 268484 communiques
In the present invention, the face that what is called is sought its improvement distortion (so-called " arch distortion ") of buckling outward, be the flexural deformation of being seen when strengthening at the steel plate that stiffening web is welded in relatively thin (usually below 10mm), for example as shown in Figure 2, it is a kind of following phenomenon, promptly, solidification shrinkage when the fusion of the seam areas that produces because of welding heat that when the stiffening web 2 with same thickness is welded in the single face rear flank reinforcing structure intensity of steel plate 1, is produced and cooling thereafter, especially this moment mother metal and welding heat affected and complex effects that the residual stress that produces etc. are caused, make the position flat part generation buckling distortion of welding assembly, become " back of arch distortion " shown in particularly A-A ' line sectional view of Fig. 2.
Summary of the invention
The back will illustrate the occurrence cause of this buckling distortion, and the invention provides a kind of steel plate, it is by the moiety and the strength characteristics of control steel plate, particularly control strength of parent and be influenced by heat the back intensity balance, can suppress this arch distortion to greatest extent, and a kind of manufacture method that can obtain this steel plate effectively is provided.
The welding of the present invention that can the solve above-mentioned problem little steel plate of buckling is characterized in that, is YP in the yielding stress of establishing steel plate
0, tensile strength is TS
0, and this steel plate in the heat affecting in when welding simulation and the yielding stress of having given after its following thermal process be YP
1The time, YP
0(strength of parent) is that 250MPa is above, TS
0For more than the 400MPa, YP
1Below 400MPa, and YP
0/ YP
1Be more than 1.
(giving the thermal process condition)
The thermal process figure: as Fig. 1,
Give the thermal process device: use electric wave industrial of Fuji (FujiElectronic IndustrialCo., Ltd.) 50 kilowatts of thermal cycling transcribers of Zhi Zaoing.
In first preferred forms of above-mentioned steel plate of the present invention, these steel have following chemical ingredients, and satisfy as the hardenability index shown in following a or the b (DI value).
A) chemical ingredients
Contain:
C：0.005～0.12％、
Si：0.05～0.5％、
Mn：0.05～1.2％，
Surplus: Fe and unavoidable impurities
DI＝1.16×[√(C/10)]×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3.0×Mo+1)×(1.75×V+1)×(200×B+1)≤0.38
[mark in the formula is represented the containing ratio (quality %) of each element].
B) chemical ingredients
C：0.005～0.12％、
Si：0.05～0.5％、
Mn：0.05～1.2％、
N:0.002～0.007%, in addition,
Comprise at least a element that is selected from Nb:0.005～0.03%, V:0.005～0.075%, Ti:0.005～0.03%,
Surplus: Fe and unavoidable impurities
DI＝1.16×[√(C/10)]×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3.0×Mo+1)×(1.75×V+1)×(200×B+1)≤0.38
[mark in the formula is represented the containing ratio (quality %) of each element].
In addition, second preferred forms is that these steel satisfy following chemical ingredients and above-mentioned DI value.
Chemical ingredients:
C：0.005～0.12％、
Si：0.05～0.5％、
Mn：0.05～1.2％、
N:0.002～0.007%, in addition,
Comprise at least a element that is selected from Nb:0.005～0.03%, V:0.005～0.075%, Ti:0.005～0.03%, satisfy the relation of following formula (I) simultaneously:
Nb/6.63N+V/3.64N+Ti/3.41N>1…(I)
Surplus: Fe and unavoidable impurities.
In the steel plate of the invention described above,, also comprise and be selected from least a in Ca:0.0005～0.003%, Zr:0.0005～0.004%, REM:0.0005～0.005% as other element; Perhaps, as other element, also comprise be selected from that Ni:0.2% is following, Cu:0.2% following, Cr:0.2% is following, at least a in following of Mo:0.1%.
In addition, the manufacture method of the steel plate that welding buckling distortion of the present invention is little, be a kind of can be applicable to use satisfy as the method the during steel plate of the described important document of above-mentioned first embodiment, be heated to more than 950 ℃ after, when being rolling to target thickness, by with at the Ar that calculates by following formula
3The accumulation draft of the temperature province that transformation temperature is following reaches form more than 30% and is rolled and gives above-mentioned characteristic,
Ar
3(℃)＝910—310×C—80×Mn—20×Cu—15×Cr—55×Ni—80×Mo
[mark in the formula is represented the containing ratio (quality %) of each element].
In addition, when being applied to use the steel plate of satisfied as the described important document of above-mentioned second embodiment, after being heated to more than 950 ℃, when being rolling to target thickness, reach more than 50% by making along the accumulation draft of thickness of slab direction in the temperature province of 850～900 ℃ of medial temperatures, be rolling to the target thickness of slab and finish rollingly, and give above-mentioned characteristic.
According to the present invention, for example the steel plate of using as the hull member not only can keep competent structural strength, and weldability is good, the face that can suppress simultaneously to accompany with the welding to greatest extent distortion (so-called " arcuation distortion ") of buckling outward.Consequently, the correction process after can not needing to weld in fact improves operating efficiency, and the while is the reduction of erection time obviously.In addition,, be suppressed to minimal steel plate, a kind of steel plate that satisfies target property can cheap be provided by using use level with the alloying element of costliness etc. according to manufacture method of the present invention.
Description of drawings
The figure that is subjected to heating curve of Fig. 1 thermal process that to be expression give the steel plate that is for experiment of the heat affecting in when welding simulation;
Fig. 2 is the explanatory view that steel plate is welded " the arch distortion " seen when building;
Fig. 3 is the ratio YP of yielding stress with the yielding stress at welding heat affected position of expression steel plate mother metal
0/ YP
1For buckle the outward graphic representation of influence of deflection of the face that causes by " general character metamorphism ";
Fig. 4 be the yielding stress at the welding heat affected position of expression and by " arch metamorphism " buckle the outward graphic representation of relation of deflection of the face that causes;
Fig. 5 represents to put out Ar in order from the various experimental datas of having used the steel (above-mentioned steel 1) that do not add carbide forming element
3Draft below the transformation temperature is for the tensile strength (TS of mother metal
0) the graphic representation of influence;
Fig. 6 be expression from the various experimental datas of having used the steel (above-mentioned steel 2) that are added with carbide forming element, put in order out at the accumulation draft of 850～900 ℃ temperature province tensile strength (TS for mother metal
0) the graphic representation of influence;
Fig. 7 is that the graphic representation that gathers has been carried out in expression to the relation of the yielding stress at DI value and welding heat affected position;
Fig. 8 is illustrated in the figure of size of the tension test sheet of the steel plate that is for experiment that uses in the experiment.
Embodiment
Present inventors are under foregoing situation, the face that is called as " arch metamorphism " that is produced when the being conceived to welding procedure distortion of buckling outward, inquire into being used to develop its genesis mechanism that effectively prevents " the arch metamorphism " of method, confirm as follows.
In welding is built, the fused part takes place during welding and thermal contraction takes place neighbouring (below be sometimes referred to as " near the portion welding line ") when being cooled to normal temperature.
When above-mentioned thermal contraction and since near the welding line portion its all around by stiffening web restriction, so can not free shrink, therefore, strengthen the deflection deficiency of shrinking generation by viscous deformation.Consequently, in this zone, with the suitable stretching residual stress generation of yielding stress under its temperature.And portion is cooled under the state of normal temperature near with the welding line of this steel plate, and the stretching residual stress suitable with yielding stress under near the welding line the normal temperature produces.
The part of leaving from welding line on the basis of this phenomenon produces compressive residual stress according to the stretching residual stress equilibrated mode that produces with near portion welding line.
And, when above-mentioned compressive residual stress surpasses buckling during critical strength of this steel plate, generation face buckle outward distortion, i.e. " arch metamorphism ".
(2) are meant " near the residual stress that portion produces the welding line depends on the yielding stress degree that has been subjected to welding heat affected part " in the above-mentioned mechanism, therefore, suppress the face distortion of buckling outward, think that the consideration of note point is effective down.
Promptly find, importantly " because the heat affecting when welding is heated to the Ar with this steel plate
3During to normal temperature, the yielding stress of this area part is extremely low in cooling (cooling) in transformation temperature above zone ", under this situation, the compressive residual stress that the position produced that leaves welding line is also low, correspondingly is difficult to cause the face distortion of buckling outward.
So, in steel, add the alloying element amount for a long time, be heated to Ar by welding heat
3The zone that transformation temperature is above, the process of cooling thereafter easily forms hard tissue such as bainite and martensite, and the yield-stress ratio mother metal at welding heat affected position is also high often.Under this situation,, the compressive residual stress level that the position produced of the welding line that departs from this steel plate is uprised if cause by above-mentioned mechanism (2), therefore, face buckle outward the distortion reduction can not realize.Therefore, consider above-mentioned mechanism (2) and, reduce interpolation alloying element with quench hardening effect and must try one's best for the rising of the yielding stress that suppresses welding heat affected position.
Also confirmed in addition, though the compressive residual stress that causes because of the thermal contraction at welding heat affected position produces aforesaid the distortion of buckling outward, but, this face buckle outward the distortion not only relevant, also relevant with the yielding stress of this steel plate (mother metal) with residual stress at that time.That is, under the situation that the residual stress of par exists, the more little easy more generation buckling distortion of the yielding stress of mother metal self.Result to this problem further investigation finds, if make the yielding stress of steel plate (mother metal) be higher than the yielding stress at the heat affecting position of this steel plate, then can suppress the arch metamorphism as much as possible.
In addition, be heated to Ac
3The above zone of transformation temperature (having finished the temperature of α → γ reverse transformation) discharges to airborne heat by the heat passage of peripherad steel plate and from surface of steel plate and is cooled to normal temperature, determined that by formed tissue inter-variable when γ → α phase transformation takes place the intensity at welding heat affected position almost only depends on chemical ingredients again.Confirmed also that on the other hand because strength of parent is except that chemical ingredients, also the variation with rolling condition changes, thereby by controlling chemical ingredients and rolling condition, the intensity at may command strength of parent and welding heat affected position.
According to such opinion, among the present invention, as the first necessary important document, it is the ratio of relation that makes the yielding stress at the yielding stress of steel plate and the heat affecting position of welding during this steel plate, i.e. (yielding stress of steel plate)/(yielding stress at the heat affecting position when welding this steel plate) is more than 1, in other words, if make (yielding stress of steel plate), then can prevent the arch metamorphism to greatest extent exactly greater than (yielding stress at the heat affecting position when welding this steel plate).
So, in the present invention, because the yielding stress of steel plate (mother metal) is made as (YP
0), the yielding stress the during thermal process of the heat affecting when having been simulated welding has been carried out standardization, therefore will be defined as (YP to the yielding stress that this steel plate is given after the above-mentioned thermal process
1), should (YP
0/ YP
1) be to be defined as the first necessary important document more than 1.More preferably (YP
0/ YP
1) value be more than 1.2.
But, cross when low in the yielding stress of steel plate mother metal, owing to can not guarantee necessary structural strength as the Structural Steel Plate undercapacity of hull structural member etc., thereby will be much larger than " more than the 250MPa ", " more than the 400MPa " as the yielding stress of steel plate mother metal and the lower value separate provision of tensile stress.
In addition, Fig. 3 is from a plurality of experimental datas that comprise following embodiment, puts out (the yielding stress YP of steel plate in order
0The yielding stress YP at welding heat affected position of)/(
1) ratio for buckle the outward graphic representation of influence of deflection of face, establish this (YP
0/ YP
1) ratio be 1.0 o'clock, the deflection of buckling outward surpasses 4.0 if not enough its is worth then face, and is relative therewith, if this ratio is more than 1.0, then the face deflection of buckling outward is a low value below 4.0.
In addition, Fig. 4 is the graphic representation that expression is put in order the deflection of buckling outside the yielding stress of welding heat affected zone position and the face from the experimental data of as much, according to this graphic representation, if the yielding stress at welding heat affected position is below the 400MPa, then face is buckled outward, and to be suppressed in allowed band be below the 4.0mm to deflection, relative therewith, if surpass 400MPa, then face is buckled deflection outward obviously above 4.0mm.Therefore, the yielding stress at welding heat affected position being suppressed at below the 400MPa, is effective for suppressing the arch metamorphism.
Then, for finding to be used to obtain the preferred important document of above-mentioned characteristic, the hardenability parameter DI that is made of the overall target that contains the few affected element of yielding stress at steel plate mother metal and welding heat affected position and these elements has been carried out research repeatedly.
It found that, importantly, as first important document of the best that is used to obtain above-mentioned characteristic, be according to employed chemical composition of steel, with the DI value that calculates by above-mentioned formula be 0.38 (unit: following form inch), regulate the content that constitutes element.
Why stipulate the upper limit of these DI values, be because when after reduce the quench hardening of steel self, weld and heat affecting position thereof being heated to high temperature, being cooled near the normal temperature, rise because of quench hardening has stoped generation intensity, will cause the weld of maximum reason of arch distortion and the yielding stress after the welding of heat affecting position suppress alap cause.
Point out that in passing the hardenability parameter surpasses 0.38 if above-mentioned DI value is steel, the quench hardening height of steel then, correspondingly, quench hardening takes place and makes the yielding stress rising at this position in this weld of the process of cooling after welding and heat affecting position.Therefore, as the explanation of being done in above-mentioned mechanism (2), near the stretching residual stress height at the position welding line, correspondingly also having increased should the stretching residual stress and departing from the compressive residual stress that the position was produced of this welding line to carry out the equilibrated form, becomes the reason that promotes the arch metamorphism.Therefore, in order to suppress this phenomenon, just must be suppressed at below 0.38 as the DI value of its root.Though the most preferably value of these hardenability parameters is below 0.37, more preferably below 0.36, but, if the hardenability parameter of steel is low excessively, then the intensity at welding heat affected position is insufficient, be difficult to guarantee necessary intensity as structural steel, thus preferred more than about 0.22, more preferably more than about 0.24.
And contain under an amount of Nb, V, the situation of Ti as the precipitation-hardening element at steel, because because of the carbide of these elements and the precipitation-hardening of carboritride improve strength of parent, although thereby the DI value of these steel also can be about 0.09, be preferably more than about 0.16.
In addition, if the carbon equivalent of steel is low excessively, then because explanation as doing in following manufacture method, though but it is insufficient to be used to improve the processing strength of parent of strength of parent, but be difficult to guarantee necessary intensity as structural steel, thereby preferably its lower value is more than about 0.15, more preferably more than about 0.16.
Below, the optimum chemical composition at steel used in the present invention is described.Steel of the present invention are divided into that following to state bright two kinds be steel 1 and steel 2.
The optimum chemical composition of the steel 1 that use among the present invention is C:0.005～0.12%, Si:0.05～0.5%, Mn:0.05～1.2%, surplus is Fe and unavoidable impurities, perhaps except that these elements, also contain N:0.002～0.007%, and comprise at least a element that is selected from Nb:0.005～0.03%, V:0.005～0.075%, Ti:0.005～0.03%, stipulate the reasons are as follows of content of these various compositions.
C：0.005～0.12％
C is because also the most effective and cheap except guaranteeing necessary structural strength as the steel plate mother metal, thereby the C element that must add that is, if 0.005% of less than must be a content more than this value because of undercapacity.More preferably more than 0.01%, select more than 0.03% especially.On the other hand, in the present invention, owing to reduce the arch metamorphism by the quench hardening characteristic that suppresses aforesaid welding heat affected position, and the DI value of necessary control steel, because this DI value is subjected to the influence of C big, thereby C content mostly is below 0.12% most, and is preferred below 0.11%, more preferably below 0.10%.
Si：0.05～0.5％
Because Si has the function as the deoxidation material of molten steel, be the element that promotes the DI value and help the raising of strength of parent simultaneously, thereby preferably contain at least about 0.05%, preferred more than 0.10%.But, because the interpolation of temperature will improve the quench hardening at welding heat affected position and make the residual stress that produces in this zone become big, make this regional low-temperature flexibility variation simultaneously, be the upper limit with 0.5% therefore, preferred 0.4% is controlled at followingly, more preferably is controlled at below 0.3%.
Mn：0.05～1.2％
Because Mn plays a part to improve strength of parent, promotes the DI value simultaneously and helps to improve strength of parent, therefore preferably contains more than 0.05% at least.Preferred more than 0.10%, more preferably more than 0.20%.But, will make the quench hardening rising at welding heat affected position and to make the residual stress that produces in this zone become big because over-drastic adds, make this regional low-temperature flexibility variation simultaneously, therefore, at most being the upper limit below 1.2%.Preferably be controlled at below 1.0%, more preferably be controlled at below 0.8%.
Except that above-mentioned element, containing under more than one the situation of N and Nb, V, Ti,
N is 0.002～0.007%, and more than one of Nb:0.005～0.03%, V:0.005～0.075%, Ti:0.005～0.03%;
In the present invention, N combines with Nb, V, Ti and becomes the generation source of nitride, and these nitride turn into helping to improve the toughness at welding heat affected position by playing the thick of austenite structure of suppressing welding heat affected position effectively.In order to bring into play this effect effectively, preferably make N and Nb, V, Ti in above-mentioned scope.
The impurity that its remainder of employed steel comes down to Fe and sneaks into inevitably among the present invention wherein, comprises Al, P, S etc.That is, Al is the element that utilizes as reductor, for the solid solution oxygen that fully reduces in the steel worsens with the toughness that suppresses mother metal, preferably contains more than 0.02%.But, worsen becoming the formation source of non-metal kind inclusion and becoming the toughness that makes base metal tenacity and welding heat affected position owing to excessively contain, therefore preferably be controlled at below 0.05%, more preferably be controlled at below 0.04%.
In addition, because P, S are the elements of sneaking into inevitably in the steel, and become inclusion and the base metal tenacity of steel plate and the toughness at welding heat affected position are caused disadvantageous effect, therefore, preferably P is controlled at below 0.05%, more preferably is controlled at below 0.03%, especially preferably be controlled at below 0.02%, preferably S is controlled at below 0.02% in addition, more preferably is controlled at below 0.01%, especially preferably be controlled at below 0.005%.
And the DI value that satisfies the steel 1 of mentioned component condition is the value that calculates by above-mentioned formula and is necessary for below 0.38.
Secondly, the optimum chemical composition of employed steel 2 among the present invention, except that the content range of C, the Si of above-mentioned steel 1 defined, Mn, N content especially is selected from least a content of Nb, V, Ti except satisfying, the relation of N content and Nb, V, Ti content satisfies " Nb/6.63N+V/3.64N+Ti/3.41N〉1 ", and surplus is made of Fe and unavoidable impurities.
Promptly, though N and aforesaid Nb, V, Ti form nitride and help to improve the toughness at welding heat affected position, but, in the steel 2 of second embodiment of the present invention, by making Nb, V, Ti form carbide (perhaps nitride) and separate out, utilization is separated out hardness and is improved to seek intensity, fastening with the pass of the mass ratio of Nb, V, Ti, no matter they have formed nitride, still guarantee all must satisfy as the growing amount of nitride and as the important document that is used to bring into play structural hardening effect " Nb/6.63N+V/3.64N+Ti/3.41N〉1 ".
And by come effectively effectively utilization with above-mentioned form as the precipitation-hardening effect of the nitride of Nb, V, Ti, and temperature and draft during the hot rolling system during the manufacturing steel plate that will address by accurate control, can not improve the yielding stress at welding heat affected position, but can utilize these elements when rolling carbide (perhaps nitride) the precipitation-hardening effect and improve the yielding stress and the tensile stress of steel plate mother metal effectively.
Contain (preferred more than 0.008%) more than the Nb:0.005%, (preferred more than 0.010%) more than the V:0.005%, more than the Ti:0.005% (preferred more than 0.008%), and satisfy under the situation of " Nb/6.63N+V/3.64N+Ti/3.41N〉1 ", will bring into play the effect of these Nb, V, Ti effectively.But, except the high reason of these element expensive material costs, if their too high levels, then cause the quantity and the volume fraction of the carbide (perhaps nitride) of being separated out excessive, except the low-temperature flexibility that reduces mother metal and stretchiness etc., thereby be easy to make by welding heat dissolved precipitate and separate out the yielding stress that improves welding heat affected position again, consequently, because producing makes the arch deflection also become big problem, therefore preferred: as to be controlled at below 0.03% Nb (preferred below 0.025%, more preferably below 0.020%), be controlled at below 0.075% V (preferred below 0.060%, more preferably below 0.050%), Ti is controlled at (preferred below 0.025%, more preferably below 0.020%) below 0.03%.
And the best DI value of steel 2 that satisfies the mentioned component condition is for the value that calculates by above-mentioned formula and be necessary for below 0.38.
And contain under an amount of Nb, V, the situation of Ti as the precipitation-hardening element at steel, owing to improve strength of parent by the carbide of these elements and the precipitation-hardening of carbide, thereby the lower limit of the DI value of these steel also can be about 0.09.But, preferably more than about 0.16.
The necessary formation element of the preferred above-mentioned steel 1,2 that use as above among the present invention, surplus is Fe and unavoidable impurities, but, according to circumstances, can also contain at least a other element that is selected from Ca:0.0005～0.003%, Zr:0.0005～0.004%, REM:0.0005～0.005%; Perhaps also can also comprise be selected from that Ni:0.2% is following, Cu:0.2% following, Cr:0.2% is following, Mo:0.1% at least a other element in following.
Above-mentioned Ca, Zr, REM, have by being that inclusion (be easy to when rolling extend along rolling direction inclusion) carries out the effect that spheroidization suppresses internal fissure and takes place from the be full of cracks at welding heat affected position with A such as MnS, above-mentioned in this Ca, Zr, REM are equivalent elements, and independent interpolation by separately or two or more mixing are added and effectively brought into play these effects.In order effectively to bring into play these effects, preferred: as to contain Ca:0.0003% above (more preferably more than 0.0007%), contain Zr:0.0005% above (more preferably more than 0.0010%), contain REM:0.0005% above (more preferably more than 0.0010%).But, if their too high levels, then make the drawback of base metal tenacity and the deterioration of stretching ductility owing to the oxide compound (CaO etc.) that generates a large amount of each element, therefore preferably respectively Ca is controlled at (more preferably below 0.0025%) below 0.003%, Zr is controlled at (more preferably below 0.004%) below 0.004%, REM is controlled at (more preferably below 0.00335) below 0.005%.
In addition, Ni, Cu, Cr, Mo have the effect that improves hardenability, improves strength of parent, be equivalent elements in this, and these effects are effectively brought into play in independent interpolation by separately or two or more mixing interpolations.But, if these elements are too much, the yielding stress at welding heat affected position is uprised, consequently, except make the arch deflection also become big, also produce the problem that makes the surging raising manufacturing cost of expense of raw materials, therefore, preferably: Ni is controlled at (more preferably below 0.1%) below 0.2%, Cu is controlled at (more preferably below 0.1%) below 0.2%, Cr is controlled at (more preferably below 0.1%) below 0.2%, Mo is controlled at (more preferably below 0.05%) below 0.1%.
Secondly, because above-mentioned chemical ingredients has been carried out specific steel 1,2, all be that carbon equivalent is low and strengthening element content is also few, thereby in the middle of directly the common steel plate of use is created conditions, can not guarantee its competent intensity as the steel plate mother metal, cause as the structural steel undercapacity.Therefore, for this is carried out practicability,, must not only guarantee necessary strength to being used to get both but also show low this characteristic of yielding stress at the welding line annex position of using this steel plate and work hard as ship structure steel plate.So to being used for creating conditions and study wherein.
The hot rolling microstructure of the low-carbon low-alloy steel that designs in the present invention is based on ferritic phase, as the method that to improve this ferrite subject organization be the intensity of steel plate, can enumerate:
The reinforcement that utilizes the miniaturization of ferrite crystal grain and carry out;
The reinforcement that the work hardening of the ferritic phase that the rolling of the temperature province of utilization below the Ar3 transformation temperature carried out is effectively used;
The solution strengthening that utilizes the interpolation of alloying element and carry out;
Apply flexibly the reinforcement that precipitation strengths such as metallic carbide are carried out.
Wherein, need not add the method that alloying element just can strengthen is above-mentioned 1), 2), and for 1) put into practice, just must be rolled with very large 1 Bath draft, perhaps must make the rolling power of very large roller mill, perhaps only just can realize, and in reality, be difficult to stable the realization in the rolling size corresponding to situations of condition such as (rolling width are narrow, rolling thickness is thin).In addition, 3) enhancement method in, have only the reinforcement about 30 very high～50MPa just can expect.Correspondingly, 2) enhancement method is a kind of by rolling temperature is carried out the technology that stringent regulations can realize, and above-mentioned 4) method to can be applicable to contain the precipitation strength element be Nb, V, Ti and satisfy the steel of " Nb/6.63N+V/3.64N+Ti/3.41N 〉=1 ".
Therefore, in the present invention, satisfy in use under the situation of steel plate of member condition of above-mentioned steel 1, for the strength of parent YP that both guarantees to stipulate
0, guarantee the yielding stress YP at welding heat affected position simultaneously
1Yielding stress YP with mother metal
0Ratio (YP
0/ YP
1) be more than 1, and when after being heated to this steel plate more than 950 ℃, being rolling to target thickness so that by following formula calculate at Ar
3The form that the accumulation draft of the temperature province that transformation temperature is following reaches more than 30% is rolled,
Ar
3(℃)＝910—310×C—80×Mn—20×Cu—15×Cr—55×Ni—80×Mo
[the chemical mark in the formula is represented the containing ratio (quality %) of each element].
At this moment, along with at Ar
3The raising of the draft of the temperature province that transformation temperature the is following and processing ferritic structure is increased makes the yielding stress of mother metal uprise simultaneously.Particularly compare with tensile strength, yield strength promotes very big.On the other hand, if welding heat affected position is heated to Ar
3More than the transformation temperature, then since from ferrite (α) sex change to austenite (γ), thereby existing processing ferritic structure restores before making heating, shows and in thereafter the corresponding yielding stress of the ferritic structure that process of cooling produced.Because its yielding stress roughly depends on the ratio of the ferritic structure that has carried out second phase (so long as perlite) branch rate and solution strengthening, thereby decide yielding stress according to adding the alloying element amount.Therefore, if improve Ar in rolling when making steel plate
3The draft of the temperature province that transformation temperature is following then can improve the yielding stress and the tensile stress of steel plate mother metal by work hardening, particularly can increase substantially yielding stress.
Based on found that of such viewpoint repeated experiments, if will be at Ar
3The draft of the temperature province that transformation temperature is following is controlled at more than 30%, the yielding stress that then not only can guarantee steel plate more than the 250MPa, tensile strength more than 400MPa, and can guarantee the yielding stress YP of steel plate
0Yielding stress YP with welding heat affected position
1Ratio (YP
0/ YP
1) be more than 1.Based on this fact, satisfy in use under the situation of steel plate of member condition of steel 1, when being rolling to the target thickness of slab again after being heated to this steel plate more than 950 ℃, must make to Ar
3The accumulation draft of the temperature province that transformation temperature is following reaches more than 30%, more preferably reaches more than 40%.
In addition, to be expression put out Ar in order to Fig. 5 from the various experimental datas of steel (above-mentioned steel 1) of carbide forming element have been added in use
3The following draft of transformation temperature is subjected to the tensile strength (TS of mother metal
0) influence graphic representation, it shows will guarantee Ar in order to ensure the tensile strength more than the 400MPa level
3The following draft of transformation temperature is more than 30%.
Then, satisfy in use under the situation of steel plate of member condition of above-mentioned steel 2, for the strength of parent YP that both guarantees to stipulate
0, guarantee the yielding stress YP at welding heat affected position simultaneously
1Yielding stress YP with mother metal
0Ratio (YP
0/ YP
1) be more than 1, and when after being heated to this steel plate more than 950 ℃, being rolling to target thickness, reach by accumulation draft and to finish rollingly more than 50%, just must bring into play the effect that the precipitation strength element is Nb, V, Ti effectively 850～900 ℃ temperature province.
In addition, though the temperature province of separating out of the carbide of Nb, V, Ti (perhaps nitride) is about below 900 ℃, but under the situation that is not rolled but places, can not separate out fully, just must after rolling, carry out temper in order effectively to utilize precipitation strength.On the other hand, separating out under the situation that temperature province is rolled of these carbide etc., because of the rolling rejected regions such as transposition that import become the gathering ground of precipitate forming element (Nb, V, Ti) or the generation ground of carbide, perhaps by utilizing transposition diffusion (with the about VELOCITY DIFFUSION more than 10 times of common diffusion (being called volume diffusion)) to promote the gathering of precipitate forming element to promote separating out of carbide, can not reach 70～80% the reinforcement of having implemented temper even do not carry out temper after rolling yet.
But, be not simply as long as be rolled separating out within the temperature province, in order both to guarantee among the present invention above-mentioned strength of parent (yielding stress YP as purpose
0More than 250MPa, tensile strength TS
0More than 400MPa), make YP simultaneously
0/ YP
1Reach more than 1, and after being heated to raw steel more than 950 ℃, when being rolling to target thickness, the accumulation draft 850～900 ℃ temperature province is reached more than 50%.
In addition, along with the increase of the drafts in separating out temperature province such as above-mentioned carbide, and the amount of the carbide of being separated out when making the cooling of finishing after rolling etc. increases, and correspondingly, has also promoted the yield strength and the tensile strength of steel plate mother metal.On the other hand, if welding heat affected position is heated to Ar
3More than the transformation temperature, then owing to the phase transformation of generation α (ferrite) to γ (austenite), the carbide solid solution of being separated out when also making the cooling after rolling in addition, thereby the existing ferritic structure that has carried out precipitation strength restores before making heating.Therefore, become not enough with being used for the generation of separating out and can not fully strengthening in process of cooling thereafter.
Therefore, be subjected to the yielding stress and the tensile stress of welding heat affected part, shown on the corresponding intensity of ferritic structure that is produced with cooling back and added some (about 40～50% during temper) precipitation strength again.In addition, if improve the draft in the temperature province of separating out at carbide etc., the intensity that then can improve the steel plate mother metal effectively is yielding stress especially.Consequently, the yielding stress at welding heat affected position inferior limit can be controlled at, the yielding stress of steel plate mother metal can be only improved simultaneously.
Result based on such viewpoint repeated experiments shows, when being rolling to the target thickness of slab again after being heated to more than 950 ℃, the accumulation draft 850～900 ℃ temperature province reached more than 50%, more preferably reach finish more than 55% rolling best.
In addition, to be expression put in order out from the various experimental datas of steel (above-mentioned steel 2) of carbide forming element have been added in use Fig. 6 is subjected to the tensile strength (TS of mother metal at the accumulation draft of 850～900 ℃ temperature province
0) graphic representation of influence, it shows in order to ensure the tensile strength more than the 400MPa level, will guarantee to reach more than 50% at the accumulation draft of 850～900 ℃ temperature province.
Moreover, Fig. 7 represents to put in order out the graphic representation of relation of the yielding stress at DI value and welding heat affected position from the experimental data that comprises following embodiment, this figure shows, by DI value (inch) is controlled at below 0.38, just the yielding stress at welding heat affected position can be controlled at the low value below the 400MPa.
In addition, steel plate thickness of the present invention is not particularly limited, and can be applicable to the steel plate of all thickness, and still, what more effectively bring into play effect of the present invention is that thickness is Plate Steel above about 4.5mm.Though the upper limit of steel plate thickness is not particularly limited, be generally about 10mm below.
Embodiment
Enumerate embodiment below and specify the present invention.Much less the present invention is not subjected to following embodiment restriction, and it is certainly suitably implemented in the scope of described aim about meeting after changing, and these all are contained in technical scope of the present invention.
In addition, as follows in the test method that following embodiment adopted.
Yielding stress YP
0, YP
1Measurement
Test board shape: with reference to Fig. 8
Give the thermal process device: use electric wave industrial of Fuji (Fuji Electronic IndustrialCo., Ltd.) 50 kilowatts of thermal cycling transcribers of Zhi Zaoing.
Buckle the outward measurement of deflection (arch distortion see a small amount of) of face
Single face at the steel plate that respectively is for experiment (thickness 6mm), go up after the stiffening web material that steel plate as shown in Figure 2 downcuts according to following condition welding, measure the face that the exposes deflection (a) of buckling along each block (1)～(12) respectively outward with the form of A-A ' wiring diagram of Fig. 2, obtain its mean value.
Welding conditions
Welding current: 280A,
Weldingvoltage: 32V,
Welding speed: 58～62cm/min,
Weld heat input: about 9kJ/cm,
Weld seam waist height: 5mm,
Welding material: (Kobe Steel Ltd) makes MG-50 (diameter 1.2mm) to Kobe Steel Plant of Co., Ltd..
Experimental example 1
The steel of the chemical ingredients shown in the his-and-hers watches 1 carries out metallurgy and foundry and the steel plate that obtains, is rolled according to the condition shown in the table 1, downcuts the test board (Nippon Kaiji Kyokai: the U1 test board) carry out tension test of specified dimension from the steel plate that obtains.In addition, implement to carry out tension test again after the welding heat affected described heat treated of simulation, the result is charged to table 2,3 in the lump for identical test board.
Can carry out the parsing of following form based on table 1～3.
In table 1, steel grade A～G is the steel that moiety given to this invention and DI value all satisfy regulation important document of the present invention, and steel grade H～N is the various contrast materials that some aspect of moiety given to this invention and DI value satisfies regulation important document of the present invention.
And table 2 is moiety, DI value, creates conditions and all satisfy the embodiment of prescribed condition of the present invention that its expression arch deflection is the little value below 4.0mm all.
Relative therewith, some aspect that table 3 is moiety, DI value, create conditions is less than the Comparative Examples of the prescribed condition of unabridged version invention, or its general character deflection to exceed allowed band be 4.0mm, or the tensile strength of mother metal do not depart from the 400MPa level, and is inconsistent with purpose of the present invention.
Claims (8)
1, a kind of little steel plate of buckling distortion that welds is characterized in that, is decided to be YP in the yielding stress with steel plate
0, tensile strength is decided to be TS
0, and the heat affecting will be to this steel plate simulation welding the time and given following thermal process after yielding stress be decided to be YP
1The time, YP
0More than 250MPa, TS
0More than 400MPa, YP
1Below 400MPa, and YP
0/ YP
1Be more than 1,
Give the condition of thermal process
Thermal process figure: as Fig. 1.
2, steel plate as claimed in claim 1 is characterized in that, steel have following chemical ingredients, and satisfies following hardenability index (DI value),
Chemical ingredients contains in quality %:
C：0.005～0.12％、
Si：0.05～0.5％、
Mn：0.05～1.2％、
Surplus: Fe and unavoidable impurities,
DI＝1.16×[√(C/10)]×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3.0×Mo+1)×(1.75×V+1)×(200×B+1)≤0.38
Mark in the formula is represented the mass percent containing ratio of each element.
3, steel plate as claimed in claim 1 is characterized in that, steel have following chemical ingredients, and satisfies following hardenability index (DI value),
Chemical ingredients contains in quality %:
C：0.005～0.12％、
Si：0.05～0.5％、
Mn：0.05～1.2％、
N:0.002～0.007%, in addition,
Also contain from Nb:0.005～0.03%, V:0.005～0.075%, Ti:0.005～0.03%, select at least a,
Surplus: Fe and unavoidable impurities,
DI＝1.16×[√(C/10)]×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3.0×Mo+1)×(1.75×V+1)×(200×B+1)≤0.38
Mark in the formula is represented the mass percent containing ratio of each element.
4, steel plate as claimed in claim 1 is characterized in that, steel have following chemical ingredients, and satisfies following hardenability index (DI value),
Chemical ingredients contains in quality %:
C：0.005～0.12％、
Si：0.05～0.5％、
Mn：0.05～1.2％、
N:0.002～0.007%, in addition,
Also contain from Nb:0.005～0.03%, V:0.005～0.075%, Ti:0.005～0.03%, select at least a, and satisfy the relation of following formula (I),
Nb/6.63N+V/3.64N+Ti/3.41N>1…(I)
Surplus: Fe and unavoidable impurities,
DI＝1.16×[√(C/10)]×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3.0×Mo+1)×(1.75×V+1)×(200×B+1)≤0.38
Mark in the formula is represented the mass percent containing ratio of each element.
5, as each described steel plate in the claim 2～4, it is characterized in that, as other element, described steel also contain select at least a in quality % from Ca:0.0005～0.003%, Zr:0.0005～0.004%, REM:0.0005～0.005%.
6, as each described steel plate in the claim 2～4, it is characterized in that, as other element, it is at least a that described steel are selected also containing below Ni:0.2%, below the Cu:0.2%, below the Cr:0.2%, below the Mo:0.1% in quality %.
7, a kind of manufacture method of welding the little steel plate of buckling distortion is characterized in that, with satisfying after the plate slab of each described member condition is heated to more than 950 ℃ in the claim 2～4, when being rolled down to the target thickness of slab, with the Ar that is being calculated by following formula
3The mode that the accumulation draft of the temperature province that transformation temperature is following becomes more than 30% is rolled, and entitle requires the characteristic described in 1 thus,
Ar
3(℃)＝910—310×C—80×Mn—20×Cu—15×Cr—55×Ni—80×Mo
Mark in the formula is represented the mass percent containing ratio of each element.
8, a kind of manufacture method of welding the little steel plate of buckling distortion, it is characterized in that, after being heated to the plate slab that satisfies the described member condition of claim 4 more than 950 ℃, when being rolled down to the target thickness of slab, making along the medial temperature of thickness of slab direction is that the accumulation draft of 850～900 ℃ temperature province is more than 50%, be rolled down to the target thickness of slab and finish rollingly, entitle requires the characteristic described in 1 thus.
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| CN106480380A (en) * | 2015-09-02 | 2017-03-08 | 沈阳大陆激光工程技术有限公司 | A kind of laser manufactures the iron(-)base powder of low-speed heave-load marine diesel engine piston annular groove |
| CN110835711A (en) * | 2019-10-22 | 2020-02-25 | 河钢股份有限公司 | Steel plate for high heat input welding and preparation method thereof |
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| JP3462943B2 (en) * | 1995-10-03 | 2003-11-05 | 新日本製鐵株式会社 | Steel sheet having high fatigue strength at welded portion and method for producing the same |
| JP3434434B2 (en) * | 1997-06-10 | 2003-08-11 | 新日本製鐵株式会社 | Steel material excellent in fatigue crack propagation characteristics and method of manufacturing the same |
| JP3367388B2 (en) * | 1997-08-04 | 2003-01-14 | 住友金属工業株式会社 | High ductility and high toughness steel sheet and manufacturing method thereof |
| JP4220788B2 (en) * | 2003-01-21 | 2009-02-04 | 株式会社神戸製鋼所 | Low yield point steel plate for earthquake resistant members and method for producing the same |
| JP3954607B2 (en) * | 2004-11-04 | 2007-08-08 | 株式会社神戸製鋼所 | Steel plate with less weld buckling deformation and its manufacturing method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106480380A (en) * | 2015-09-02 | 2017-03-08 | 沈阳大陆激光工程技术有限公司 | A kind of laser manufactures the iron(-)base powder of low-speed heave-load marine diesel engine piston annular groove |
| CN110835711A (en) * | 2019-10-22 | 2020-02-25 | 河钢股份有限公司 | Steel plate for high heat input welding and preparation method thereof |
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