CN101522355A - Joint welded by electron beam with excellent unsusceptibility to brittle fracture - Google Patents
Joint welded by electron beam with excellent unsusceptibility to brittle fracture Download PDFInfo
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Abstract
High-strength steel plates having a yield strength of 355 MPa or higher and a thickness larger than 50 mm are butt-welded by electron beam welding to form a welded joint having a sufficiently high fracture toughness value dc. The butt-welded joint has been regulated so that the hardness of the weld metal part is 110-220% based on the hardness of the base plates and the width of the weld metal partis up to 20% of the thickness of the base plates. Preferably, the weld metal of the welded joint has been regulated so that the amount of oxygen contained therein is 20 ppm or larger and the number o f oxide particles having a diameter of 2.0 [mu]m or larger present therein is up to 10 per mm<2>. Alternatively, the weld metal of the welded joint has preferably been regulated so as to have a nickelcontent which is 1-4 mass% and is higher by at least 0.2 mass% than that in the base plates. When the base plates are a steel material having a nickel content of 2.5 mass% or higher, the nickel conte nt in the weld metal of the welded joint has preferably been regulated to 4-8 mass%, excluding 4 mass%.
Description
Technical field
The present invention relates to welding structural body, particularly relate to the electro-beam welding joint of the occurrence features of anti-brittle fracture excellence of the welding structural body that thickness of slab is constituted greater than the steel plate butt welding of 50mm.
Background technology
Will break away from the social demand that utilizes reproducible natural energy resources from the fossil energy of oil etc. and very improve, large-scale wind-power electricity generation is also being popularized just worldwidely.
The region that is suitable for most wind-power electricity generation is the region that can constantly expect high wind, and wind-power electricity generation has also been realized with the scale in the world on the ocean.Wind power generation stepped in order on the ocean, to build, must on the ground in seabed, squeeze into the foundation of tower, in order fully to guarantee the height of the wind wheel blade of wind-power electricity generation from the seawater face, foundation also needs sufficient length.
Therefore, wind power generation stepped foundation is the heavy in section tubular construction that has about thickness of slab 100mm, about diameter 4m, and the overall height of tower reaches more than the 80m unexpectedly.Near the simple and easy and so huge works of welding assembly expeditiously of the seashore of requirement construction site.
So, produced thickness of slab as described above to be reached unexpectedly 100mm utmost point steel plate with high efficiency and weld this unexistent in the past requirement at the scene.
Usually, electro-beam welding method is the welding method that can utilize the high density high-energy beam to weld expeditiously, but need keep high vacuum state in vacuum chamber and weld, and therefore, in the past, the size of welding steel plate was restricted.
To this, in recent years, as the welding method of the utmost point steel plate about can be expeditiously on-the-spot welding thickness of slab 100mm, the electro-beam welding method that can under low vacuum, construct (RPEBW:ReducedPressured Electron Beam Welding: the decompression electron beam welding) by the institute of welding exploitation of Britain and propose a plan (WO99/16101 with reference to).
By using this RPEBW method to weld occasion as wind power generation stepped and so on large structure, also expectation can only make the part of welding be in vacuum locally to weld expeditiously.
; on the other hand; this RPEBW method; compare with the method for in vacuum chamber, welding; be under the state that vacuum reduces, to weld; therefore be difficult to guarantee above-mentioned this new problem occurs by the toughness of electron beam melting, the motlten metal part (below be also referred to as the weld metal zone) of solidifying then.
Known by Japanese kokai publication hei 3-248783 communique etc., for such problem, in the past, (inserted metal by metal insert with tabular Ni etc.; Insert metal) be attached at solder side and carry out electron beam welding, making the Ni content of weld metal thus is 0.1～4.5%, improves the toughness of the charp impact value etc. of weld metal.
; when using the welding of RPEBW method; because in the method; elements such as the Ni in the metal insert are not diffused into welding heat affected zone equably; and the difference of the hardness of weld metal and welding heat affected zone (below be also referred to as the HAZ district) is increased; therefore instead make the tough sexual deviation in HAZ district bigger, this problem is very clear and definite.
Usually, as the index of the security of estimating welded structure quantitatively, known have try to achieve by CTOD test, based on the fracture toughness value δ c value of fracture mechanics.The welding of in the past employing RPEBW method and the welding point that obtains, the tough sexual deviation of above-mentioned welding heat affected zone is bigger, therefore is difficult to fully guarantee fracture toughness value δ c value.
On the other hand, in TOHKEMY 2005-144552 communique, propose: in order to ensure the fracture toughness value K of the large-line energy welding point of gas shielded arc welding etc.
c, control and make that the hardness ratio of weld metal and mother metal is below 110%, thereby improve the fracture toughness K of weld metal zone and mother metal portion boundary (below be also referred to as FL portion)
cMethod.
Yet, fracture toughness value δ c in order to ensure electro-beam welding joint, must satisfy the two fracture toughness value δ c of FL portion and weld metal zone, when similarly making the hardness of weld metal zone be reduced to 110% when following of hardness of mother metal with the large-line energy welding point, generation can not be guaranteed the problem of the fracture toughness value of the weld metal zone in the electro-beam welding joint.
In addition; the electron beam welding connection; it is the energy that utilizes electron beam to have; the method of the fusion of the mother metal of weld zone elder generation being solidified again and welding is difficult to utilize as the large-line energy arc-welding process of gas shielded arc welding etc. welding wire etc. easily to control the characteristic of the hardness of weld metal zone and fracture toughness value δ c etc.
Summary of the invention
In view of above prior art, the purpose of this invention is to provide: make the two the fracture toughness value δ c raising of border (FL portion) of weld metal zone that weld metal zone in the electro-beam welding joint and local stress increases especially and welding heat affected zone, stably improve the scheme of the fracture toughness of welding point.
The present inventor investigates the engineering properties of mother metal and welding point in order to achieve the above object.It found that, existence by the metal insert that uses for the toughness that improves the weld metal zone, the intensity of weld metal zone, hardness rise, intensity, hardness than mother metal are high significantly, thus with the boundary vicinity of the welding heat affected zone (HAZ district) that joins with the weld metal zone, local stress increases, and therefore, the fracture toughness value δ c of FL portion reduces.
In addition, based on this opinion, in yield strength is more than the 355MPa level, in the electron beam welding of thickness of slab greater than the high-strength steel plate of 50mm (preferably approximately being greater than 50mm and below 100mm), reduction as the joint toughness of realizing to prevent causing by high coupling (over matching), can stably guarantee the new joint design technology of the welding point of excellent toughness, constitute the present invention.
Described main idea of the present invention is as follows.
(1) a kind of electro-beam welding joint of the occurrence features of anti-brittle fracture excellence, it is the butt joint of welding structural body, it is characterized in that, the hardness of weld metal zone greater than the hardness of mother metal part 110% and be mother metal below 220% of hardness partly, and the width of weld metal zone is below 20% of thickness of slab of mother metal part.
(2) according to above-mentioned (1) described electro-beam welding joint, it is characterized in that, as mother metal, use is in quality %, contain C:0.02～0.2%, Mn:0.8～3.5%, S:0.0005～0.0025%, Al: less than 0.02%, Ti:0.01～0.05%, the value of the Pcm that is represented by following (a) formula is the steel below 0.5% more than 0.12%, and the amount that the amount of the oxygen that contains in the weld metal of welding point (O) is more than the 20ppm, particle diameter is the oxide more than the 2.0 μ m is 10/mm
2Below.
Pcm＝C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B ·······(a)
According to above-mentioned (2) described electro-beam welding joint, it is characterized in that (3) particle diameter is that 0.1 μ m is above and be 30～600/mm less than the amount of the Ti oxide of 2.0 μ m
2
(4) according to above-mentioned (1) described electro-beam welding joint, it is characterized in that, in the weld metal of this welding point, contain the Ni of 1～4 quality %, and the Ni that contains is Duoed more than the 0.2 quality % than the content in mother metal.
(5) according to above-mentioned (4) described electro-beam welding joint, it is characterized in that, in weld metal, contain the B below the 10ppm.
(6) according to above-mentioned (1) described electro-beam welding joint, it is characterized in that, as above-mentioned mother metal, use contains the steel of the above Ni of 2.5 quality %, the content of the Ni that contains in the weld metal of above-mentioned welding point is in quality %, greater than 4% and be below 8%.
According to each described electro-beam welding joint of above-mentioned (1)～(6), it is characterized in that (7) above-mentioned welding structural body is thickness of slab to be carried out butt welding greater than the high-strength steel sheet of 50mm form.
According to the present invention, when to be 355MPa level, thickness of slab to yield strength greater than the high-strength steel sheet of 50mm carry out electron beam welding, can form fully high welding point of fracture toughness value δ c.
And, even do not use the occasion of metal insert, also can reach purpose of the present invention effectively according to the Ni content of mother metal.
Description of drawings
Fig. 1 is the figure of the influence that causes of the δ c value of the hardness butt welded seam metal of expression weld metal zone and mother metal and HAZ, FL portion.
Fig. 2 is that the hardness ratio, γ particle diameter of expression weld metal zone and mother metal softened the figure of the influence that the relation of the CTOD value of width and HAZ, FL portion brings to HAZ.
Fig. 3 is expression: for the test film of thickness of slab 70mm, adopt FEM (three-dimensional finite element method) resolve weld metal zone (WM) and welding heat affected zone (HAZ) boundary portion (FL) and, at welding heat affected zone (HAZ) otch is set, at the CTOD at otch tip (Crack TipOpening Displacement: the figure of the example of the result who obtains to the crackle opening stress distribution of each position that direction of crack propagation leaves from the otch tip during crack tip opening displacement) for 0.05mm.
Fig. 4 is illustrated in the docking section to insert the Ni paper tinsel or do not insert the Ni paper tinsel and the figure of CTOD result of the test when adopting the welding of RPEBW method.
Fig. 5 is expression and the figure of the firmness change of the welded-joint of the same situation of Fig. 1.
Fig. 6 is the figure of the relation of the oxide number more than fracture toughness value and the particle diameter 2.0 μ m of expression weld metal.
Fig. 7 is the difference of Ni content of Ni content, weld metal and mother metal steel plate of expression weld metal and the figure of the relation between the fracture toughness value δ c.
Fig. 8 is Ni content butt welded seam metal area, the FL in the expression weld metal, the figure of the influence of the fracture toughness value δ c in HAZ district.
The specific embodiment
General electro-beam welding joint, for a part of fusion of mother metal part, solidify again and for the weld metal zone that forms, guarantee difficulty of needed fracture toughness δ c.Therefore, in the past, when electron beam welding, known had the metal insert that inserts nickel foil etc. in bevel for welding portion (to insert metal; Insert metal), the quenching degree of weld metal zone is improved, utilize this cooperative effect, guarantee the method for fracture toughness value δ c.
; present inventors find; when this method of employing; the fracture toughness value δ c on the border of the welding heat affected zone in the electro-beam welding joint, particularly weld metal zone and welding heat affected zone (FL portion) reduces significantly, can not fully guarantee the fracture toughness value δ c of electro-beam welding joint.
So present inventors manufacture experimently the steel plate that yield strength is the 460MPa level, be that 4% metal insert inserts in the bevel for welding with Ni content, implement electron beam welding, measure the fracture toughness value δ c of the welding point that obtains by the CTOD test and estimate.
The result of the CTOD test of above-mentioned welding point distinguishes, though the fracture toughness value δ c of weld metal zone demonstrates the above abundant high value of 0.2mm, the fracture toughness value δ c of the boundary portion in weld metal zone and HAZ district (FL portion) demonstrates the following extremely low value of 0.02mm.
Then, investigate found that of fracture origination point in the CTOD test of above-mentioned welding point in minute detail:
(i) Duan Lie occurrence positions is border (welding melt run [the FL]) portion of weld metal zone (WM) and welding heat affected zone (HAZ), and, become the result of distributional pattern of local stress of the driving force (driving force) of fracture in the CTOD test of adopting the three-dimensional finite element method to resolve at above-mentioned welding point
(ii) the local stress of FL portion is subjected to the influence of hardness of the weld metal zone (WM) of adjacency significantly.
Fig. 3 represents: for the test film of thickness of slab 70mm, adopt FEM (three-dimensional finite element method) resolve weld metal zone (WM) and welding heat affected zone (HAZ) boundary portion (FL) and, at welding heat affected zone (HAZ) otch is set, at the CTOD at otch tip (Crack Tip OpeningDisplacement: the example of the result who obtains to the crackle opening stress distribution of each position that direction of crack propagation leaves from the otch tip during crack tip opening displacement) for 0.05mm.
Distinguish by this figure, (iii) be approximately greater than 50mm and when 70mm is following when thickness of slab, constraint (restraint) degree (binding force) in the thickness of slab direction increases significantly, if the strength ratio mother metal (BM) of weld metal zone (WM), the intensity height (occasion of WM-H) of welding heat affected zone (HAZ), then the boundary portion (FL) of local stress (WM) and welding heat affected zone (HAZ) in the weld metal zone increases (with reference to among the figure [WM-H] and ■ [WM-L]) significantly.
On the other hand, the occasion (occasion of WM-H) that the intensity of the strength ratio mother metal (BM) of weld metal zone even (WM), welding heat affected zone (HAZ) is high, in welding heat affected zone (HAZ), local stress does not increase yet, and the occasion lower with the intensity of weld metal zone (WM) (occasion of WM-L) is identical substantially.
Can think thus, the reason that δ c value reduces be because, the occasion (occasion of WM-H) that the intensity of the strength ratio mother metal (BM) of (WM), welding heat affected zone (HAZ) is high in the weld metal zone, the boundary portion (FL) of (WM) and welding heat affected zone (HAZ) in the weld metal zone, the cause that local stress increases.
Promptly, through the result of above-mentioned parsing, the present inventor finds, (iv) enlarging markedly for the local stress that is suppressed at weld metal zone (WM) and the boundary portion (FL) of welding heat affected zone (HAZ), improve δ c value, must reduce the intensity of weld metal zone (WM) as much as possible.
Yet find, when the hardness that makes the weld metal zone reduces, can not guarantee the quenching degree of weld metal zone (WM), therefore generate thick ferrite, its result, the CTOD value reduces.
At this, based on above-mentioned analysis result, make the hardness [Hv (WM)] of weld metal zone do various variations, measure the CTOD value δ c of FL portion, with δ c value with respect to found that " hardness [Hv (BM)] of the hardness of weld metal zone [Hv (WM)]/mother metal " draws, shown in " ● " among Fig. 1, if the hardness [Hv (WM)] of weld metal zone is suppressed to be below 220% of the hardness of mother metal [Hv (BM)], then can prevent the reduction of the fracture toughness value δ c that the increase by the stress of part causes.
Though δ c value is high more good more, in the standard of Norway Nippon Kaiji Kyokai (DNV) etc., under design temperature, require the value about 0.1～0.2mm, in view of the above, the δ c value as target is defined as more than the 0.15mm in the present invention.
Moreover, in the electro-beam welding joint that obtains by previous methods, be difficult to more than stably guaranteeing for 0.15mm at the fracture toughness value δ c under-20 ℃.
So, though it is lower than the hardness [Hv (BM)] of mother metal by the hardness [Hv (WM)] that makes the weld metal zone, the δ c of FL portion improves, but if the hardness [Hv (WM)] of weld metal zone is exceedingly reduced, then the δ c value of weld metal zone reduces, its result can not guarantee the fracture toughness value δ c of electro-beam welding joint.
What present inventors discussed found that, as among Fig. 1 by shown in zero symbol, if the hardness [Hv (WM)] of weld metal zone is guaranteed more than 110% of hardness [Hv (BM)] for mother metal, then for the weld metal zone, can guarantee needed CTOD value.
Fig. 2 illustrates the hardness ratio of weld metal zone and mother metal, the influence that the γ particle diameter brings to the relation of the CTOD value of softening width of HAZ and FL portion.It is big more to demonstrate the HAZ width, the tendency that the CTOD value of FL portion improves more.This be because, can relax the cause of the influence of strength matching because HAZ is softening, the HAZ width is preferably more than the 3mm.
In addition, the present inventor finds, with the generation of local stress in the welding molten thread (FL) of weld metal zone adjacency or distribute by the domination of the hardness of weld metal zone, but with the HAZ district of FL adjacency in " zone of softening " big occasion, existence can relax the tendency of the local stress of FL.
According to experimental result shown in Figure 2, the softening width of HAZ is big more, can see above-mentioned mitigation phenomenon more, has occasion more than the 3mm at this softening width, and this mitigations phenomenon becomes remarkable especially, so HAZ softens width and is preferably more than the 3mm.
The hardness in HAZ district is lower than the hardness of mother metal more, and the local stress of FL portion reduces more on principle, but according to present inventor's experimental result, and what can see clearly that the local stress of FL portion reduces effect is that the hardness of the hardness ratio mother metal in HAZ district is hanged down the situation more than 5%.
Therefore, the peak width of the welding heat affected zone of the hardness below 95% of preferred softening hardness to the mother metal part that is not subjected to heat affecting is more than the 3mm.
In addition,,, worry in softening part, to concentrate strain, therefore be preferably below the 10mm from guaranteeing the viewpoint of strength of joint, fatigue strength when the width in the zone of welding heat affected zone is 10mm when above.
In welding point, in order to ensure the CTOD value δ c of regulation, in that to locate to make local stress not increase as the welding molten thread (FL) of the most fragile portion of welding point very important, this states in front, but make simultaneously, near the occurrence features of anti-brittle fracture of the microcosmic FL improve also very important.
The result of investigation, near the investigation mechanism that brittle fracture takes place FL finds out, becomes the starting point of fracture at the pro-eutectoid ferrite of original austenite periphery generation, the upper bainite that generates with strip in original austenite inside, ferrite side plate bar etc.
Find that the rive section unit in when fracture of this upper bainite, ferrite depends on the particle diameter of austenite phase,, and make upper bainite, ferritic size little, can improve the occurrence features of anti-the brittle fracture therefore by suppressing the original austenite particle diameter little.
In addition, the result of present inventor's investigation, when " hardness [Hv (BM)] of the hardness of weld metal zone [Hv (WM)]/mother metal " approach the present invention regulation 220% the time, can ignore the reduction of the fracture toughness value δ c that the influence by the strength matching in weld metal and HAZ district and tissue causes.
Therefore, in order under such condition, also stably to guarantee the fracture toughness value δ c of joint, preferably make and weld molten thread (FL) adjacency welding heat affected (HAZ) district the original austenite particle diameter be below the 100 μ m, suppress thickization (with reference to Fig. 2) of original austenite particle diameter.
In addition, when electron beam welding, when the irradiation area of electron beam became big, the heat input that gives steel plate was excessive, and thickization of tissue meeting of FL portion guaranteeing that stably on the fracture toughness value δ c of FL portion be not preferred.
In addition, adopt the occasion of RPEBW welding production electro-beam welding joint, compare, have the tendency of the width increase of weld metal with the welding point of in vacuum chamber, under high vacuum state, making by electronic welding (EBW welding).
Therefore, in the present invention, in order also stably to guarantee the fracture toughness value δ c of electro-beam welding joint in the occasion that adopts the RPEBW welding, the width that makes the weld metal zone is below 20% of thickness of slab of mother metal part.
The high-strength steel sheet of the welding structural body that uses among the present invention can be to be made with structural steel by the welding that known one-tenth is grouped into.For example be preferably in contain C:0.02～0.20%, Si:0.01～1.0%, Mn:0.3～2.0%, Al:0.001～0.20% by quality %, below the N:0.02%, below the P:0.01%, below the S:0.01%, the steel that its surplus is made of Fe and the impurity that can not keep away is for basic, corresponding to the desired character of raising of strength of parent, joint toughness etc., contain the one or more kinds of steel among Ni, Cr, Mo, Cu, W, Co, V, Nb, Ti, Zr, Ta, Hf, REM, Y, Ca, Mg, Te, Se, the B.
The thickness of slab of steel plate is not particularly limited, but obviousization of this problem is the high-strength steel sheet of thickness of slab greater than 50mm.
For the hardness of the weld metal zone ratio with the hardness of mother metal is suppressed within the scope of the invention, must avoid in weld metal, generating thick ferrite as far as possible.Therefore, according to the having or not of the quenching degree of mother metal, use that thickness of slab is adjusted metal insert, its chemical composition.
Under the situation of using metal insert, can use the Ni alloy, contain the Fe alloy of Ni, be not grouped into but be not defined as specific one-tenth, can be grouped into according to the one-tenth of mother metal to wait and select.
Electron beam welding for example, when thickness of slab is 80mm, is carried out under the condition about voltage 175V, electric current 120mA, speed of welding 125mm/ divide.Usually, 10
-3The following welding of high vacuum that mbar is following, even but the joint that under the rough vacuum that adopts easy equipment also can construct, vacuum about for example 1mbar, is welded, also within the scope of the invention.
Then, under the occasion of not using metal insert and its occasion of use, under the hardness of weld metal zone 110% and the condition 220% below, fracture toughness value δ c is discussed for being used for for the condition of the value of excellence for the hardness of mother metal part greater than the hardness of mother metal part.
(A) do not use the occasion of metal insert
In the occasion of not using metal insert, with a part of fusion of mother metal, and former state ground solidifies the formation weld metal again, therefore when only stipulating the ratio of weld metal zone and the hardness of mother metal part, the fracture toughness value δ c that can guarantee in the weld metal zone produces the limit.
Make the means of the toughness raising of electro-beam welding joint as do not use metal insert in the past, for example, the technology that proposes in known Japanese kokai publication sho 62-64486 communique, the TOHKEMY 2003-201535 communique etc.
This technology, be in the cooling procedure after welding, form most fine oxide based non-metallic inclusions, with this field trash from austenite during to ferrite transformation the nuclear as this phase transformation use, form the microscopic structure that contains the fine acicular ferrite that demonstrates good toughness morely, obtain the technology of the weld metal of tenacity excellent thus.
Therefore, the viewpoint of the reduction of the joint toughness that causes from the high coupling that prevents by the hardness of mother metal and weld metal zone, for the technology of putting down in writing in the above-mentioned patent documentation of utilizing fine oxide to improve the microscopic structure of weld metal zone is further developed, use the two fracture toughness value δ c of the weld metal zone of occasion of metal insert and FL portion to improve, can guarantee stably that the technology of welding point of the fracture toughness of welding point is discussed.
So, find that in this process when having the field trash of specific size more than with certain frequency in weld metal, fracture toughness value δ c produces deviation.Promptly, investigate found that of fracture origination point in the CTOD test that use to add the electro-beam welding joint that steel plate that Ti disperses fine oxide forms in minute detail, become the fracture in the CTOD test starting point be the above oxide of certain size, by reducing the frequency that exists of such oxide, can reduce the deviation of the fracture toughness value δ c in the CTOD test.
Below, describe for the experiment that obtains above-mentioned opinion.
To contain the steel plate butt joint of the thickness 70mm of C:0.04%, Mn:1.8%, S:0.003%, Al:0.006%, Ti:0.02%, at first, in order to investigate the difference of the welding point that causes by having or not of metal insert, a kind of situation is that (a) inserts the Ni paper tinsel in the docking section, another kind of situation is that (b) do not insert the Ni paper tinsel, all adopts the RPEBW method to weld then.
In the welded-joint separately after welding, produce test film from steel plate thickness direction 1/4 and 3/4 this two position, (WM district), weld metal zone and mother metal portion boundary portion (FL portion) and HAZ district are provided with otch in the weld metal zone, carry out the CTOD test, and investigated the firmness change of welded-joint.
The CTOD result of the test is shown in Fig. 4, and the firmness change of welded-joint is shown in Fig. 5.
Be inserted with in the docking section under the situation of (a) of Ni paper tinsel, the hardness height of weld metal zone, reduce at the fracture toughness value δ of FL portion c, relative therewith, under the situation of (b) that do not insert the Ni paper tinsel, the hardness of weld metal zone is low, and the degree of the high coupling of hardness is relaxed, fracture toughness value in FL portion is and the value of weld metal zone same degree that the fracture toughness value δ c value of weld metal zone is compared with the situation of not inserting the Ni paper tinsel also for hanging down the degree of some.
Then, investigated the dispersion situation of the oxide of the weld metal zone under (a) and the situation (b).
Under the situation of (b), particle diameter is that 0.1 μ m is above and be 400/mm less than the amount of the Ti oxide of 2.0 μ m
2, fine Ti oxide disperses in weld metal equably, and particle diameter is that the number of the above oxide of 2 μ m is 2/mm
2, its quantity is few.
On the other hand, under the situation of (a), oxide disperses state also same with the situation of (b), can't see special difference between the two.But under the situation of (a), the hardness of weld metal zone is higher, is 260% of the hardness of FL portion, can think that therefore the local stress of FL portion increases δ c step-down.
As described above, under the situation of not inserting the Ni paper tinsel, can confirm by obtaining the weld metal that suitable oxide disperses state, can relax the degree of the high coupling between weld metal zone and the HAZ district, weld metal zone and FL, therefore the HAZ district all obtains higher fracture toughness value δ c, has further investigated the relation of the fracture toughness value δ c of oxide in the weld metal zone under the situation of not inserting the Ni paper tinsel and weld metal zone and FL portion.
To contain C:0.04%, Mn:1.8%, S:0.003%, Al:0.006%, Ti:0.02%, oxygen content is at 10～250ppm and steel plate different, thickness 70mm adopts the RPEBW method to postwelding, similarly produce test film, carry out the mensuration of fracture toughness value and oxide number from the weld metal zone of steel plate thickness direction 1/4 and 3/4 this two position.
Moreover, the number of field trash, be that the image of SEM (SEM) etc. is handled by image, and obtain each area of oxide, will with the diameter of a circle of its area equivalence (circle equivalent diameter) as the particle diameter of this oxide, obtaining particle diameter is the per unit area number of the above oxide of 2 μ m.
The results are shown in Fig. 6, as can be known size be the number of the above oxide of 2 μ m be 10/below the mm2, the deviation of the fracture toughness value δ c of weld metal reduces greatly, and, can obtain fully high value.
In addition, and then obtain the kind and the dispersion condition of the Ti oxide that can obtain the good weld metal of fracture toughness value by same experiment.
Its result is more than the 0.1 μ m and less than the amount of the Ti oxide of 2.0 μ m to be 30～600/mm when particle diameter as can be known
2The time, can obtain the good weld metal zone of fracture toughness value δ c.
Then, further discuss for the chemical composition of the mother metal of the dispersion situation that obtains such oxide.
Its result as can be known, as the mother metal that constitutes welding structural body, use is in quality %, at least contain C:0.02～0.2%, Mn:0.8～3.5%, S:0.0005～0.0025%, Al: less than 0.02%, Ti:0.01～0.05%, the value of Pcm be more than 0.12% the steel below 0.5% for well.
C: in order to ensure intensity, need 0.02% at least, but surpass at 0.2% o'clock, solidification cracking takes place easily as welding structural body.
Mn: in order to ensure intensity and toughness, need 0.8% at least, but surpass at 3.5% o'clock, quenching degree too increases, and toughness reduces.
S: be the element that toughness is reduced, need make it below 0.0025%.,, the complex of oxide and MnS is examined use as the intragranular phase transformation, preferably contain more than 0.0005% in order to make it to form MnS.
Al: in the manufacturing of steel, add usually as deoxidier, but the ferrite transformation karyogenesis ability of Al oxide is minimum, therefore in the present invention, adopt Ti to carry out deoxidation, therefore the content with Al is defined as less than 0.02%, more preferably below 0.005%, in addition, can not contain especially yet.
Ti: in the present invention, when using as deoxidier, making it generate the Ti oxide, by the microscopic structure miniaturization of Ti oxide, the fracture toughness in weld metal and HAZ district is improved, is essential element aspect above-mentioned.In order to form necessary Ti oxide, need more than 0.01% at least, but surpass at 0.05% o'clock, the amount of oxide, size become excessive, worry to become the starting point of fracture.
O:, also essential in mother metal in order to form the Ti oxide.For the particle diameter that satisfies the Ti oxide in the weld metal, the condition of number, must in weld metal, contain at least more than the 20ppm, more preferably more than the 40ppm.Oxygen content in the weld metal, not only according to the content in steel of base metal, also the vacuum according to electron beam welding changes, though therefore can not uniformly be defined in the content in the mother metal, the O content in the mother metal is when adopting the electron beam welding of common high vacuum, be defined as more than the 40ppm, in addition, when adopting the low above-mentioned RPEBW of vacuum, be preferably more than the 30ppm.O content in the weld metal for the particle diameter that satisfies oxide described later, the condition of number, is preferably below the 250ppm, so the upper limit of the O content in the mother metal also is preferably same degree.
And the ratio in order not use metal insert with the hardness of weld metal zone and the hardness of mother metal is suppressed at above-mentioned scope, must control to make and guarantee the quenching degree of weld metal zone, avoids generating pro-eutectoid ferrite as far as possible in the weld metal zone.For this reason, the Pcm value of being represented by following (a) formula with mother metal is decided to be more than the 0.12 quality %.In addition, when the Pcm value surpassed 0.5 quality %, the hardness of weld metal zone was too high, therefore will on be defined as 0.5 quality %, when more preferably below the 0.38 quality %.
Pcm＝C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B ·······(a)
The steel of the mother metal that becomes electro-beam welding joint when not using metal insert under the limit that satisfies the mentioned component condition, can be foregoing known welding steels.
When not using metal insert, be by the Ti oxide is disperseed imperceptibly, from austenite during to ferrite transformation, nuclear as this phase transformation uses, form the microscopic structure contain the fine acicular ferrite that shows good toughness morely, thereby obtain the weld metal of tenacity excellent, but this moment, as shown in Figure 6, must avoid particle diameter is that the amount of the above oxide of 2.0 μ m surpasses 10/mm2.When being present in the steel with surpassing this amount, can become the starting point of the fracture in the CTOD test, the reason of deviation appears in the fracture toughness value that becomes the weld metal zone.
In addition, by making the particle diameter of bringing into play the Ti oxide of function as intragranular phase transformation nuclear is more than the 0.1 μ m and less than 2.0 μ m, making the amount of Ti oxide of the particle diameter of this scope is 30～600/mm2, can form the microscopic structure that contains fine acicular ferrite morely.
Moreover the fine Ti oxide of a part is separated out MnS around it, forms complex with MnS thus.This complex is more effective as intragranular phase transformation nuclear, is to comprise such complex in Ti oxide of the present invention.
For in the weld metal zone, making particle diameter is that the amount of the above oxide of 2.0 μ m is no more than 10/mm
2, and to make particle diameter be that 0.1 μ m is above and be 30～600/mm less than the amount of the Ti oxide of 2.0 μ m
2,, preferably use the size of oxide to be suppressed in the following steel of 2.0 μ m as mother metal.
For this reason, in the deoxidation step of the steel that become mother metal, must be noted that and carry out Control and Inclusion Removal.
The deoxidation of steel can be used Al usually, but if add the Al of the strong deoxidant element of conduct, then deoxygenation carries out fast, can generate the above bigger oxide of 2 μ m.Therefore, carry out deoxidation, generate smaller oxide by adopting the deoxidizing capacity Ti littler than Al.; if once drop into a large amount of Ti; form thick oxide easily; therefore for the oxygen content in the molten steel is reduced interimly; the timing input of control Ti, or behind the Ti that drops into as weak deoxidant element, Al, the Ca of the strong deoxidant element of conduct of input minute quantity, Mg etc.; suppress the generation of the above thick oxide of 2 μ m thus, can generate the minute oxides of 0.1～2 most μ m.
(B) occasion of use metal insert
The steel that become mother metal have the steel of various Ni content, if the ratio of hardness with the hardness of mother metal of weld metal zone is adjusted in the Ni content only by mother metal and the combination of the Ni content of the metal insert of use, then can produce the situation of the fracture toughness value δ c that can not guarantee better welding point.
Therefore, at first, influence for the Ni content of investigating weld metal, the trial-production yield strength is the steel plate of 355MPa level, will by (a) pure Ni or (b) Ni content be that the metal insert paper tinsel of the thickness 0.3mm that forms of the Fe-Ni alloy of 20 quality % is inserted into butt welding portion, implement electron beam welding,, measure fracture toughness value δ c, firmness change and the Ni concentration of CTOD test for the welding point that obtains.
The CTOD test of welding point and the result that hardness is measured, under the situation of the metal insert that the pure Ni that uses by above-mentioned (a) forms, the hardness height of weld metal zone, fracture toughness value δ c is more than the 0.2mm, demonstrated abundant high value, but the fracture toughness value δ c of FL portion is below the 0.02mm, demonstrates extremely low value.On the other hand, the occasion of the metal insert that forms at the Fe-Ni alloy that uses by above-mentioned (b), the hardness of weld metal zone is low, has relaxed the degree that the height of hardness mates, about fracture toughness value δ c, weld metal zone and FL portion all demonstrate the above abundant high value of 0.2mm.
In addition, measuring the result of the average N i content of weld metal, is 8.5 quality % when stating the metal insert of (a) in the use, is 2.5 quality % when using the metal insert of (b).According to this value, the Ni content of mother metal and weld metal poor is 8.0 quality % in the occasion of (a), is 2.0 quality % in the occasion of (b).
As known from the above, by with the Ni content in the weld metal, be limited in suitable scope, can prevent the reduction of the joint toughness that the high coupling by the hardness of weld metal zone and mother metal causes according to relation with the Ni content of mother metal.
Secondly, proper range for the difference of the Ni content of the proper range of investigating the Ni content in the weld metal and weld metal and mother metal, use the steel plate of above-mentioned trial-production, the metal insert that Ni content is different inserts in the bevel for welding, implement electron beam welding, produce test film respectively from the welded-joint that obtains, HAZ side (the FL of (WM district) and FL portion in the weld metal zone, the HAZ district) otch is set, implement the CTOD test, measure the test of fracture toughness value δ c (the following CTOD value that also is called simply), estimate for guaranteeing that the necessary Ni of fracture toughness value δ c measures.
For each sample, about the δ c value that obtains, be divided into WM district and FL, the HAZ district is above good zero, WM portion of 0.15mm and FL, at least one side in HAZ district less than 0.15mm bad ●, for each sample, the results are shown in Fig. 7 with what the difference of the Ni amount of the Ni amount of weld metal and weld metal and mother metal steel plate was drawn.
At this, the δ c value as target is decided to be more than the 0.15mm as previously mentioned, is the boundary with this value, is categorized as good sample of δ c value and the bad sample of δ c value.
As shown in Figure 7, the Ni content in weld metal is the scope of 1～4 quality %, and, Duo 0.2 quality % when above than the Ni content of mother metal, WM district and FL, the HAZ district all can guarantee required CTOD value.
And, measure WM district and FLHAZ district all can guarantee the CTOD value that 0.15mm is above example, weld metal zone and the hardness of mother metal part, the variation of the hardness before and after the FL portion, the hardness that the result can confirm the weld metal zone is in following ranges: greater than mother metal hardness partly 110% and be mother metal below 220% of hardness partly.
As can be known from the above results, use the welding point that electron beam welding forms that passes through of metal insert, relaxing in the local stress of FL portion, the Ni content that makes weld metal is 1～4 quality %, and Duo more than the 0.2 quality % than the content in mother metal, this is to guaranteeing that the CTOD value is effective.
As the steel that become mother metal, can be the steel made from structural steel by the welding that as described above known one-tenth is grouped into, also can be the steel that does not add Ni especially.
In addition, in when welding, though contain the metal insert of Ni in the docking section configuration, must be in the weld metal of welding point, containing the Ni of 1～4 quality %, and the Ni that contains welds than the mode that the Ni content of mother metal is Duoed more than the 0.2 quality %.As metal insert, must be the metal insert that satisfies the composition of this condition, be not grouped into but be not defined as specific one-tenth especially.
For example, can enumerate contain that C:0.01～0.06%, Si:0.2～1.0%, Mn:0.5～2.5%, Ni:50% are following, Mo:0～0.30%, Al:0～0.3%, Mg:0～0.30%, Ti:0.02～0.25%, the following Fe alloy of B:0.001%, but the content of Ni particularly, the chemical composition of steel that must be considered as welding base metal is selected, and makes to obtain the weld metal zone that its mean concentration satisfies the condition of the invention described above.
In addition, making weld metal contain the occasion of Ni, preferably make weld metal contain the following B of 10ppm.B has the generation that suppresses grain boundary ferrite, improves the effect of the toughness of weld metal, but considers aspect such as heat cracking, is decided to be below the 10ppm.
The adding method of B can be from the steel that become mother metal, also can be from metal insert, and how to add can.Moreover, above-mentioned hardness poor, satisfy condition of the present invention by the Ni content that makes weld metal, and suitably adjust the steel that become mother metal and use balance between the composition of the weld metal that metal insert forms, adjust the cooling velocity after the welding, avoid the hardness of weld metal too high, can reach thus.
(C) occasion (high Ni steel) of use metal insert
, in order using in the harsher place of natural conditions, can to use and contain the above Ni of 2.5 quality %, intensity is higher, the steel of tenacity excellent at low temperatures.
For the welding point that has used the high steel of such Ni content,, can produce the situation of the fracture toughness value δ c that can not guarantee better welding point if only adopt the hardness of adjustment weld metal zone and the means of the ratio of the hardness of mother metal.
So, influence for the Ni content of investigating weld metal, trial-production contain 3 quality % Ni steel plate and do not contain these two kinds of steel plates of steel plate of Ni, will insert butt welding portion respectively by the metal insert paper tinsel that different multiple Fe-Ni alloy of Ni content or pure Ni form, implemented electron beam welding.And each welded-joint after welding is produced test film, and the HAZ side of (WM) and FL portion in the weld metal zone (FL, HAZ district) is provided with otch, implements the CTOD test, measures fracture toughness value δ c, and has measured the Ni concentration of weld metal zone.
With WM district and FL, the fracture toughness value δ c in HAZ district is with respect to the Fig. 8 that the results are shown in of the drawing of the Ni content in the weld metal based on the measurement result that obtains.
As shown in Figure 8, be under the situation of 3% steel plate at Ni content, the Ni content of weld metal (WM) is greater than 4% and at the sample of the scope below 8%, WM district (zero) and FL, HAZ district (●) all can guarantee the CTOD value that 0.15mm is above, but be in the sample of the scope beyond it, WM district or FL, any of HAZ district had to the lower CTOD value less than 0.15mm.
In addition, under the situation of the steel plate that does not contain Ni, can not get WM district (△) and FL, any of HAZ district (▲) demonstrates the sample of the above CTOD value of 0.15mm.
Moreover the δ c value as target similarly is decided to be more than the 0.15mm.
And, measure WM district and FL, the HAZ district all can guarantee the CTOD value that 0.15mm is above hardness example, weld metal zone and mother metal part the result as can be known, the hardness of weld metal zone is in following ranges: greater than the hardness of mother metal part 110% and be mother metal below 220% of hardness partly.
As can be known from the above results, the electro-beam welding joint of the steel that Ni content is high is relaxing in the local stress of FL portion, and the Ni content that makes weld metal is that this is to guaranteeing that the CTOD value is effective greater than 4% and below 8%.
At this,, be object with the high strength steel that contains the Ni more than the 2.5 quality % as the steel that form welding structural body.As the high-strength steel sheet that uses, also can be to make with structural steel by the welding that known one-tenth is grouped into.
For example can use in quality %, with C:0.02～0.20%, Si:0.01～1.0%, Mn:0.3～2.0%, Al:0.001～0.20%, below the N:0.02%, below the P:0.01%, below the S:0.01%, Ni:2.50～9.0% is basis, corresponding to the desired character of raising of strength of parent, joint toughness etc., contain and add up to one or more kinds of steel below 8%, among Cr, Mo, Cu, W, Co, V, Nb, Ti, Zr, Ta, Hf, REM, Y, Ca, Mg, Te, Se, the B.
In addition, in when welding, must contain the metal insert of Ni and weld in the docking section configuration and contain greater than 4% in the weld metal that makes at welding point and be the Ni of (quality %) below 8%.
When solidifying again, even, must contain Ni greater than 4% in order to form the tissue that under the situation that this thickization of zone generation size of microcrystal, oxide reduce, also can stably guarantee toughness by the zone of electron beam melting.In addition, when the Ni that contains greater than 8 quality %, the hardness of weld metal zone too increases, and the ratio that is difficult to satisfy weld metal zone and the hardness of mother metal part is below 220%.
As metal insert, use the paper tinsel that forms by pure Ni easier.
Calculate the thickness of the necessary pure Ni paper tinsel of Ni content that reaches target by the Ni content of the steel that become mother metal, as the size of Ni content in the weld metal of target and steel, prepare the paper tinsel of such thickness, or thin foil is carried out overlapping make of multi-disc reach required thickness, prepare metal insert thus.
Adjust make the weld metal zone hardness greater than the hardness of mother metal part 110% and be below 220% of hardness of mother metal part, and the content that makes the Ni that contains in the weld metal of welding point in quality % greater than 4% and be below 8%.
For this reason, it is important becoming the steel of mother metal by suitable adjustment and using balance between the composition of the weld metal that metal insert forms, adjust cooling velocity after the welding too high with the hardness of avoiding weld metal.
Below based on embodiment the present invention is described, but the condition among the embodiment is a condition example that adopts in order to confirm operational feasibility of the present invention and effect, the present invention is not limited by this example.Reach under the limit of purpose of the present invention not breaking away from main idea of the present invention, the present invention is the invention that can adopt the combination of various conditioned disjunction conditions.
(embodiment 1)
Preparation contains the steel plate of thickness of slab 50～100mm that the composition shown in the table 1, its surplus be made of Fe and the impurity that can not keep away, the metal insert that will contain the Fe-Ni alloy that the composition shown in the table 2, its surplus be made of Fe and the impurity that can not keep away inserts groove part, perhaps do not insert metal insert, the butt welding by electron beam welding, after the welding, the feature and the performance of welding point of having carried out pilot survey.
It the results are shown in table 3.
Hv (BM) is the mean value in the hardness of thickness of slab direction of the mother metal measured by the impression of 10kg.Hv (WM) is the thickness of slab central portion in the weld metal zone, the value of the hardness of measuring by the impression of 10kg.
Weld width be in the weld metal zone surface, the back side and, the mean value measured of this three place, thickness of slab center.
HAZ softens width, is the width from the zone of welding molten thread when the mother metal direction detection is more regional than the HAZ of the hardness softening 5% of mother metal.
The original γ particle diameter of HAZ, be with the HAZ district of welding molten thread adjacency in original austenite grains, with the suitable particle diameter of footpath (see and make the particle diameter of justifying and calculating) souvenir of circle.
About the performance of welding point, δ c (mm) is the value of trying to achieve under-10 ℃ test temperature in above-mentioned CTOD test.
Joint tensile strength (MPa) is to make the NKU1 test film, carry out the result of joint straight draw test, is the intensity of expression fracture.
As shown in table 1, the No.1 of example of the present invention～15 are various conditions examples in scope given to this invention, and δ c value demonstrates sufficient value.
In these examples, No.1～14 since Hv (WM)/Hv (BM) and weld width/thickness of slab, the softening width of HAZ in scope given to this invention, so the δ c value in the HAZ district of welding point and joint tensile strength all demonstrate sufficient value.
Moreover the routine No.14 of the present invention because the softening width of HAZ is littler than preferred range, therefore compares with the present invention's example No.1～13, and δ c value is low, but is the above good value of 0.1mm.
The present invention's example No.15, because Hv (WM)/Hv (BM) is lower than preferred range, so the quenching degree deficiency of weld metal zone, can not suppress the generation of pro-eutectoid ferrite, the δ c characteristic in HAZ district compares with the present invention's example No.1～14, is low level.
Relative therewith, comparative example No.16,18～20,22 has been because Hv (WM)/Hv (BM) has surpassed the scope of the present invention's regulation, though therefore the δ c value of weld metal zone fully, the δ c value step-down of HAZ district, FL portion.
In addition, therefore comparative example 17 and 21 can not guarantee sufficient quenching degree, the δ c value step-down of weld metal zone because Hv (WM)/Hv (BM) is lower than the scope of the present invention's regulation.
Therefore, the present invention be suitable for guaranteeing YP be the above high strength steel of 355MPa and thickness of slab be the invention of δ c value in the zone of the above heavy wall of 50mm.
Table 1 (quality %)
| Steel grade | C | Si | Mn | P | S | Ni | Ti |
| YP36 | 0.11 | 0.19 | 1.23 | 0.006 | 0.003 | 0.01 | |
| YP40 | 0.05 | 0.15 | 1.8 | 0.003 | 0.004 | ||
| YP47 | 0.08 | 0.24 | 1.22 | 0.007 | 0.002 | 0.65 | 0.01 |
| YP56 | 0.06 | 0.14 | 1.61 | 0.005 | 0.002 | 1.21 | 0.01 |
Table 2 (quality %)
| Metal insert | C | Si | P | S | Ni |
| N1 | 0.02 | 0.01 | 0.002 | 0.010 | 0.50 |
| N2 | 0.01 | 0.21 | 0.004 | 0.001 | 1.20 |
| N3 | 0.03 | 0.02 | 0.003 | 0.002 | 4.00 |
| N4 | 0.01 | 0.12 | 0.008 | 0.003 | 8.00 |
(embodiment 2)
Preparation contains the steel plate of thickness of slab 50～100mm that the composition shown in the table 4, its surplus be made of Fe and the impurity that can not keep away, by electron beam welding to postwelding, the feature and the performance of formed welding point of having carried out pilot survey.
It the results are shown in table 5.
In table 5, Hv (BM), Hv (WM), δ c (mm) obtain similarly to Example 1.Moreover, in embodiment 3,4 described later too.
As shown in table 5, the No.1 of example of the present invention～15th, oxygen content in the value of Hv (WM)/Hv (BM), chemical composition of steel, the weld metal and oxide amount be the example in scope given to this invention all, about δ c value, weld metal zone and FL, the HAZ district all demonstrates enough values.
Moreover, example 5,6,12,13 of the present invention, because particle diameter is that the above oxide number of 2 μ m is more, so the δ c value of weld metal zone is low slightly.
Relative therewith, comparative example 16, because the C content of steel and Pcm value are more than setting of the present invention, the value of Hv (WM)/Hv (BM) is greater than scope of the present invention, and, particle diameter be the oxide number of 0.1～2 μ m below setting of the present invention, so weld metal zone and FL, the δ c value in HAZ district is all insufficient.
Comparative example 17 since Hv (the WM)/value of Hv (BM) and the Pcm of steel below setting of the present invention, particle diameter be the above oxide number of 2 μ m more than setting of the present invention, so the δ c value of weld metal zone is insufficient.
Comparative example 18 because Hv (WM)/value of Hv (BM) and the Pcm of steel be below setting of the present invention, particle diameter be the oxide number of 0.1～2 μ m below setting of the present invention, so the δ c value of weld metal zone is insufficient.
(embodiment 3)
Preparation contains the steel plate of thickness of slab 50～100mm that the composition shown in the table 6, its surplus be made of Fe and the impurity that can not keep away, insert metal insert or the pure Ni metal insert contain the Fe-Ni alloy that the composition shown in the table 7, its surplus be made of Fe and the impurity that can not keep away at groove part, the butt welding by electron beam welding, after the welding, the feature and the performance of welding point of having carried out pilot survey.
It the results are shown in table 8.Moreover joint tensile strength (MPa) is to make the NKU1 test film, carries out the result of joint straight draw test, is the intensity of expression fracture.
As shown in table 8, the No.1 of example of the present invention～15th, the example of various conditions in scope given to this invention, δ c value demonstrates enough values.
On the other hand, comparative example 16,17,19,20, the Ni content in its weld metal is below 1%, its result, the δ c of weld metal is insufficient.
Comparative example 18,21,22, the Ni content in its weld metal is more than 4%, so Hv (WM)/Hv (BM) is greater than 220%, its result, though the δ c of weld metal is more abundant, the δ c of FL, HAZ is insufficient.
Table 6 (quality %)
| Steel No. | C | Si | Mn | P | | Ni | Ti | |
| 1 | 0.11 | 0.19 | 1.23 | 0.006 | 0.003 | 0.01 | ||
| 2 | 0.05 | 0.15 | 1.8 | 0.003 | 0.004 | |||
| 3 | 0.08 | 0.24 | 1.22 | 0.007 | 0.002 | 0.65 | 0.01 | |
| 4 | 0.06 | 0.14 | 1.61 | 0.005 | 0.002 | 1.21 | 0.01 |
Table 7 (quality %)
| Metal insert | C | Si | P | S | Ni |
| N1 | 0.02 | 0.01 | 0.002 | 0.010 | 30 |
| N2 | 0.01 | 0.21 | 0.004 | 0.001 | 20 |
| N3 | 0.03 | 0.02 | 0.003 | 0.002 | 8 |
| N4 | 0.01 | 0.12 | 0.008 | 0.003 | 15 |
| N5 | 100 |
(embodiment 4)
Preparation contains the steel plate of thickness of slab 50～100mm that the composition shown in the table 9, its surplus be made of Fe and the impurity that can not keep away, comprise the Ni metal insert (NA) of the composition shown in the table 10 or the metal insert (NB, NC) of Ni-Fe alloy in the groove part insertion, by electron beam welding to postwelding, the feature and the performance of the welding point that forms of having carried out pilot survey.
The result of test is shown in table 11 with the condition of welding point etc.Moreover joint tensile strength (MPa) is tested similarly to Example 3 and is obtained.
As shown in table 11, the No.1 of example of the present invention～15 are various conditions examples in scope given to this invention, about δ c value, and weld metal zone and FL, the HAZ district all demonstrates enough values.
Relative therewith, comparative example 16～19, the Ni content in its weld metal is higher, is more than 8%, so the value of Hv (WM)/Hv (BM) is more than 220%, its result, though the δ c of weld metal is abundant high value, FL, the δ c in HAZ district is extremely low value.
Table 9 (quality %)
| Steel No. | C | Si | Mn | P | | Ni | Ti | |
| 1 | 0.11 | 0.19 | 1.23 | 0.006 | 0.003 | 2.5 | 0.01 | |
| 2 | 0.05 | 0.15 | 1.8 | 0.003 | 0.004 | 3.5 | ||
| 3 | 0.08 | 0.24 | 1.22 | 0.007 | 0.002 | 5.5 | 0.01 | |
| 4 | 0.06 | 0.14 | 1.61 | 0.005 | 0.002 | 4.2 | 0.01 |
Table 10 (quality %)
| Metal insert | C | Si | P | S | Ni |
| NA | 0.02 | 0.01 | 0.002 | 0.010 | 99 |
| NB | 0.01 | 0.21 | 0.004 | 0.001 | 70 |
| NC | 0.03 | 0.02 | 0.003 | 0.002 | 50 |
Utilize possibility on the industry
According to the present invention, in the electro-beam welding joint of the large high-strength steel sheet of high strength and thickness of slab, just in case have weld defect, or fatigue crack occurs, growth, also be difficult to occur brittle fracture, therefore can prevent fatal damage, the damage of welding structural body fracture and so on.
Therefore, the present invention can obtain to improve significantly the remarkable result of the security of welding structural body, is the very high invention of value on the industry.
Among the present invention the expression number range " more than " and " following " include given figure.
Claims (7)
1, a kind of electro-beam welding joint of the occurrence features of anti-brittle fracture excellence, it is the butt joint of welding structural body, it is characterized in that, the hardness of weld metal zone greater than the hardness of mother metal part 110% and be below 220% of hardness of mother metal part, the width of weld metal zone is mother metal below 20% of thickness of slab partly.
2, electro-beam welding joint according to claim 1, it is characterized in that, as described mother metal part, use is in quality %, contain C:0.02～0.2%, Mn:0.8～3.5%, S:0.0005～0.0025%, Al: less than 0.02%, Ti:0.01～0.05%, the value of the Pcm that is represented by following (a) formula is the steel below 0.5% more than 0.12%, and the amount that the amount of the oxygen that contains in the weld metal of welding point is more than the 20ppm, particle diameter is the oxide more than the 2.0 μ m is 10/mm
2Below,
Pcm＝C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B ·······(a)。
3, electro-beam welding joint according to claim 2 is characterized in that, particle diameter is that 0.1 μ m is above and be 30～600/mm less than the amount of the Ti oxide of 2.0 μ m
2
4, electro-beam welding joint according to claim 1 is characterized in that, contains the Ni of 1～4 quality % in the weld metal of this welding point, and the Ni that contains is Duoed more than the 0.2 quality % than the content in mother metal.
5, electro-beam welding joint according to claim 4 is characterized in that, contains the B below the 10ppm in weld metal.
6, electro-beam welding joint according to claim 1 is characterized in that, as described mother metal, use contains the steel of the above Ni of 2.5 quality %, the content of the Ni that contains in the weld metal of described welding point is in quality %, greater than 4% and be below 8%.
According to each described electro-beam welding joint of claim 1～6, it is characterized in that 7, described welding structural body is thickness of slab to be carried out butt welding greater than the high-strength steel sheet of 50mm form.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006270967A JP2008087030A (en) | 2006-10-02 | 2006-10-02 | Electron beam welded joint having excellent resistance to generation of brittle fracture |
| JP271074/2006 | 2006-10-02 | ||
| JP270967/2006 | 2006-10-02 | ||
| JP271044/2006 | 2006-10-02 |
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| CN101522355A true CN101522355A (en) | 2009-09-02 |
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| CNA2007800370098A Pending CN101522355A (en) | 2006-10-02 | 2007-01-12 | Joint welded by electron beam with excellent unsusceptibility to brittle fracture |
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| JP (1) | JP2008087030A (en) |
| CN (1) | CN101522355A (en) |
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|---|---|---|---|---|
| CN102639277A (en) * | 2009-12-04 | 2012-08-15 | 新日本制铁株式会社 | Butt-welded joint formed using high-energy-density beam |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH03248783A (en) * | 1990-02-23 | 1991-11-06 | Nippon Steel Corp | Electron beam welding method for steel plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102639277A (en) * | 2009-12-04 | 2012-08-15 | 新日本制铁株式会社 | Butt-welded joint formed using high-energy-density beam |
| CN102639277B (en) * | 2009-12-04 | 2015-08-19 | 新日铁住金株式会社 | Employ the butt welded joint of high-energy-density bundle |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2008087030A (en) | 2008-04-17 |
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