CN101151120A

CN101151120A - Metallic flux cored wire, welding process with the same, and process for production of welded joints having high fatigue strength with little slag

Info

Publication number: CN101151120A
Application number: CNA2006800106048A
Authority: CN
Inventors: 糟谷正; 及川初彦; 笹木圣人
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2005-03-29
Filing date: 2006-03-29
Publication date: 2008-03-26
Anticipated expiration: 2026-03-29
Also published as: JP2006272405A; JP4603399B2; CN100525989C

Abstract

The invention provides a metallic flux cored wire which is suppressed in the formation of slag and can secure good coatability; a gas-shielded arc welding process with the wire; and a process for the production of welded joints having high fatigue strength with little slag. A wire for gas-shielded arc welding comprising a steel sheath and a metallic flux packed in the steel sheath, which contains, by mass based on the whole wire, C: 0.001 to 0.20% exclusive of graphite and SiC, graphite: 0.10 to 0.7%, Si: 0.05 to 1.2% exclusive of SiC and SiO2, Mn: 0.2 to 3.0%, P: 0.03% or below, S: 0.02% or below, and one or more of SiO2, Al2O3, Na2O, and K2O: 0.05 to 0.40% in total, the balance being iron and unavoidable impurities, with the proviso that graphite and one or more of SiO2, Al2O3, Na2O, and K2O are contained at least as the flux.

Description

Metallic flux cored wire and use its welding method and the preparation method of the few high-fatigue strength welding point of the quantity of slag

Technical field

The present invention relates to the arc welding of the first-class use of arc welding of automotive field, relate in particular to by reducing the quantity of slag on the welding bead surface that when using metallic flux cored wire to weld, takes place, may replace the metallic flux cored wire of solid core welding wire use metallic flux cored wire and use the welding method of this welding wire and the technology of the preparation method of high-fatigue strength welding point.

Background technology

For the arc-welded joint of automotive field, make in order to weld the coating operation after the end, use the few solid core welding wire of the quantity of slag that takes place in the welding.This is owing under the situation about being covered by cinder ladle in the weld metal zone, becomes and carry out coating on slag, and the cause of problem can take place the adherence of coated film and weld metal zone.

On the other hand, because the understanding of environmental problem etc. is improved, from improving the viewpoint of fuel efficiency etc., in automotive field etc., advancing lightweight.Therefore, have the tendency of using more high-intensity steel and reducing thickness of slab, but the big problem that exist this moment is the fatigue strength of weld metal zone.That is to say that even use high strength steel, the fatigue strength of its weld metal zone can not improve pro rata with steel strength, under situation, have the problem of the advantage forfeiture of using high strength steel with the fatigue strength design.

As one of means that solve such problem, once proposed by be carried out to the method that the branch design reduces the phase transition temperature of welding material and the residual stress of weld metal zone is reduced fatigue strength is improved (with reference to the spy open flat 11-138290 communique, the spy opens the 2004-1075 communique).Claim that later on such welding material is " a high-fatigue strength welding material ".This method needn't be prepared new manufacturing process, is only to substitute welding material in the past and obtain high-intensity method, can be described as the good method of efficient.

But this method also has problems.That is, the high-fatigue strength welding material contains a lot of alloying elements when composition designs, so the manufacturing cost increase, and is if the arc welding of automotive field is suitable for this welding material fully, unsatisfactory economically.Therefore, being suitable for of high-fatigue strength welding material only is limited to that fatigue becomes the position of problem, the consumption that as far as possible reduces the high-fatigue strength welding wire is necessary.But, though solid core welding wire is under the many situations of welding wire consumption, more superior than flux-cored wire economically, but the welding wire consumption after a little while, can not resemble and adjust composition by the design alteration of medicine core (solder flux) the flux-cored wire, if exist in case be ready to make the welding wire wire rod, the composition thereafter design problem that can not change etc. then, under the few situation of welding wire consumption or under the situation of a small amount of use of many kinds, economy is on the contrary not as flux-cored wire.

Flux-cored wire is to adjust with the composition that few welding wire consumption realizes obtaining the high-fatigue strength weld metal economically.But, common arc welding with flux-cored wire in the inboard of steel crust except alloying component, in order to keep good weld job and welding wire processability, also be filled with flux constituent.Therefore, under the situation that it is applicable to automotive field manufacturing arc welding welding point, welding slag can take place, the coating operation generation problem after welding.This problem by after welding again investment goods set up the slagging-off operation and can solve, but this situation can increase the cost that is used for equipment investment inevitably, so unsatisfactory.

Up to the present technology for reducing the flux-cored wire quantity of slag, once proposed many schemes.For example, the spy opens the 2000-197991 communique and provides and using welding wire to carry out suppressing under the situation of horizontal fillet welding the technology of slag generating capacity, the welding wire that welds for the mist that uses inert gas and carbon dioxide gas, according to the unit length full weight amount of above-mentioned welding wire, in quality % contain below the C:0.08%, the pack completeness of Si:0.7～1.5%, Mn:1.0～3.0%, solder flux is limited to 10～30%.But, although this invention is less than the quantity of slag of common flux-cored wire, be not with solid core welding wire mutually specific energy suppress the technology of the quantity of slag.

And the spy opens 2001-179488 communique, spy and opens the technology that 2001-287087 communique, spy are opened the 2003-94196 communique, is that the filling rate with solder flux suppresses very lowly, improves the technology of the ratio of steel crust.That is, this method is as far as possible near the technology of solid core welding wire with flux-cored wire.If think that the welding slag generating capacity of solid core welding wire is few, then by using this technology may suppress the quantity of slag.

But the solder flux amount in its welding wire of this method is few, we can say that therefore the adjustment of only leaning on flux constituent designs all compositions of welding wire and is difficult to, and the peculiar economy forfeiture of flux-cored wire takes place and the same problem of solid core welding wire.

As previously discussed, according to technology in the past, under the situation of using metallic flux cored wire, for the generating capacity with slag is suppressed at the level suitable with solid core welding wire, have to sacrifice pack completeness, otherwise, in this case, be difficult to guarantee to be used to make the alloying element addition of fatigue strength raising.That is, adopt technology in the past, still can not reach the level of using metallic flux cored wire to make the few high-fatigue strength welding point of the quantity of slag.

Because such technical problem in the past, an urgent demand use metallic flux cored wire to make quantity of slag method few, the high-fatigue strength welding point.

Summary of the invention

In view of these technical problems in the past, the objective of the invention is to: the flux-cored wire that the slag generating capacity especially lacks than in the past flux-cored wire and the manufacture method of the welding method of using it and high-fatigue strength welding point are provided.

The present inventor pays close attention to the relation of flux constituent and slag generating capacity from above viewpoint, discusses this relation and quantity of slag reduction method with great concentration.And, by the control flux constituent, to compare with flux-cored wire in the past, discovery might especially reduce the quantity of slag.The present invention constitutes according to such research, and its main idea is as follows.

(1) a kind of metallic flux cored wire; it is characterized in that: the gas shielded arc welding metallic flux cored wire that forms for intracutaneous filling solder flux outside steel; in all quality % of welding wire, contain beyond the graphite and SiC beyond C:0.001～0.20%, graphite: 0.10～0.7%, beyond the SiC and SiO ₂Si:0.05 in addition～1.2%, Mn:0.2～3.0%, restriction P:0.03% is following, S:0.02% is following and contain SiO ₂, Al ₂O ₃, Na ₂O and K ₂O more than a kind or 2 kinds and add up to 0.05～0.40%, and surplus is made up of iron and unavoidable impurities; And,, contain above-mentioned graphite and above-mentioned SiO at least as above-mentioned solder flux ₂, Al ₂O ₃, Na ₂O and K ₂More than a kind or 2 kinds of O.

(2) according to above-mentioned (1) described metallic flux cored wire, it is characterized in that: in above-mentioned metallic flux cored wire,, also contain SiC:0.05～0.6% in all quality % of welding wire.

(3) according to above-mentioned (1) or (2) described metallic flux cored wire, it is characterized in that: in above-mentioned metallic flux cored wire, the solder flux pack completeness is 10～20%.

(4) according to any one described metallic flux cored wire of (1)～(3), it is characterized in that: in above-mentioned metallic flux cored wire, in all quality % of welding wire, also contain Ni:0.5～12.0%, Cr:0.1～3.0%, Mo:0.1～3.0%, Cu:0.1～0.5% more than a kind or 2 kinds and add up to 0.2～12.5%.

(5) according to any one described metallic flux cored wire of (1)～(4), it is characterized in that: in above-mentioned metallic flux cored wire,, also contain B:0.001～0.03% in all quality % of welding wire.

(6) according to (1)～(5) any one described metallic flux cored wires, it is characterized in that: in above-mentioned metallic flux cored wire, in all quality % of welding wire, also contain Nb, V, Ti more than a kind or 2 kinds and add up to 0.005～0.3%.

(7) according to (1)～(6) any one described metallic flux cored wires, it is characterized in that: for above-mentioned metallic flux cored wire, as above-mentioned solder flux, in all quality % also contain 0.05～0.5% oxide based beyond arc stabilizer.

(8) a kind of metallic flux cored wire; the gas shielded arc welding metallic flux cored wire that forms for intracutaneous filling solder flux outside steel; in all quality % of welding wire, contain beyond the graphite and SiC beyond C:0.01～0.20%, SiC:0.6～1.2%, SiC beyond and SiO ₂Si:0.05 in addition～1.2%, Mn:0.2～3.0%, restriction P:0.03% is following, S:0.02% is following and contain SiO ₂, Al ₂O ₃, Na ₂O and K ₂O more than a kind or 2 kinds and add up to 0.05～0.4% and surplus form by iron and unavoidable impurities; And intracutaneous outside steel contains above-mentioned SiC and above-mentioned SiO as solder flux at least ₂, Al ₂O ₃, Na ₂O and K ₂More than a kind or 2 kinds of O.

(9) according to (8) described metallic flux cored wire, it is characterized in that: for above-mentioned metallic flux cored wire, intracutaneous outside steel, at least as above-mentioned solder flux, the quality % all in welding wire also contains graphite 0.05～0.4%.

(10) according to (8) or (9) described metallic flux cored wire, in above-mentioned metallic flux cored wire, in all quality % of welding wire, also contain Ni:0.5～5.0%, Cr:0.1～2.0%, Mo:0.1～2.0%, Cu:0.1～0.5% more than a kind or 2 kinds and add up to 0.5～6.0%.

(11) according to any one described metallic flux cored wire of (8)～(10), it is characterized in that: in above-mentioned metallic flux cored wire,, also contain B:0.001～0.015% in all quality % of welding wire.

(12) any one described metallic flux cored wire of basis (8)～(11), it is characterized in that: in above-mentioned metallic flux cored wire, in all quality % of welding wire, also contain Nb, V and Ti more than a kind or 2 kinds and add up to 0.005～0.3%.

(13) any one described metallic flux cored wire of basis (8)～(12), it is characterized in that: in above-mentioned metallic flux cored wire, intracutaneous outside steel, at least as above-mentioned solder flux, in all quality % of welding wire also contain 0.05～0.5% oxide based beyond arc stabilizer.

(14) a kind of gas-shielded arc welding method is characterized in that: use any one described metallic flux cored wire of (1)～(13) to come welding steel.

(15) according to (14) described gas-shielded arc welding method, it is characterized in that:, use and contain 3～25% CO as protective gas ₂, and the protective gas that constitutes by Ar gas and unavoidable impurities of surplus.

(16) according to (14) or (15) described gas-shielded arc welding method, it is characterized in that: use and in above-mentioned protective gas, also contain 4% following O ₂The protective gas of gas.

(17) according to any one described gas-shielded arc welding method of (14)～(17), it is characterized in that: the thickness of slab of above-mentioned steel plate is that 1.0～5.0mm and tensile strength are 440～980MPa.

The preparation method of the high-fatigue strength welding point that (18) a kind of quantity of slag is few is characterized in that: use any one described gas-shielded arc welding method of (14)～(17) to come welding steel.

Description of drawings

Fig. 1 is quantity of graphite and the oxide amount of expression in the metallic flux cored wire and the schematic diagram of the relation between the quantity of slag of generation when using this welding wire to weld.

The figure of the relation between the C in the weld metal that Fig. 2 is the quantity of graphite of expression in the metallic flux cored wire when using this welding wire to carry out soldering test measures.

Fig. 3 is the figure of the relation between the C in the weld metal of SiC addition when using this welding wire to carry out soldering test in the welding wire of expression metallic flux cored wire measures.

Fig. 4 is SiC amount and the oxide amount of expression in the metallic flux cored wire and the schematic diagram of the relation between the quantity of slag that produces when using this welding wire to carry out soldering test.

Fig. 5 (a) is the plane of shape of the fatigue specimen of expression welding point.

Fig. 5 (b) is the shape of fatigue specimen of expression welding point and the elevation of tired loading load direction.

Fig. 6 is the making and the figure of summer than the method that cuts of impacting test piece of explanation welding point.

The specific embodiment

Below, describe the present invention in detail.

The arc-welded joint of automotive field enters the coating operation after welding finishes, the problem of this moment is the welding slag that the welding bead surface exists.In order to ensure the adherence of coated film and joint surface, it is comparatively desirable to do one's utmost to reduce the quantity of slag.For this reason, use solid core welding wire in the technology in the past.

Usually, solid core welding wire is compared with flux-cored wire, and the slag growing amount is few, and therefore, as long as use solid core welding wire, the operation of then needn't considering especially to remove the gred just may be carried out the coating operation.But, resemble suitable joint the high-fatigue strength welding material be restricted, therefore under the few situation of welding wire consumption, solid core welding wire produces problem not as flux-cored wire from the viewpoint of economy.In order to address these problems simultaneously, it is necessary adopting the same flux-cored wire that reduces of slag generating capacity and solid core welding wire to make welding point.

Flux-cored wire has 2 kinds, promptly common type and the metallic flux cored wire that contains a lot of metal powders.The weld bead shape of common flux-cored wire is good, and in order to carry out all-position welding, guarantees the amount of slag ingredient for stipulating in its solder flux.In contrast, metal powder is many and slag ingredient is less, all-position welding difficulty in the metallic flux cored wire, but may suppress the slag growing amount.

Yet, the flux-cored wire of which kind of type no matter, in the scope of conventional art, the slag growing amount is many more than solid core welding wire.Solid core welding wire does not have the filling solder flux in welding wire, so the welding position is limited.But, when considering coating,, select solid core welding wire inevitably at technical scope in the past, the problem of welding position is resolved by the position of adjusting welded steel.

When adopting flux-cored wire to weld, know when analyzing the welding slag that produces on the welding bead, almost be SiO ₂, MnO, Al ₂O ₃, Fe ₂O ₃And so on oxide.And this tendency has been added in solder flux under the situation of alloying element of Ni, Cr, Mo etc. and has not also been changed.

Therefore, for the slag generating capacity of flux-cored wire being reduced to the level of solid core welding wire, oxide is necessary in suppressing to weld as far as possible.For this reason, it is necessary reducing the oxide that exists in the welding wire.The welding wire that the present invention uses in flux-cored wire, is defined as the metallic flux cored wire of the many solder flux of added metal composition especially, and it be the reasons are as follows.

For metallic flux cored wire in the past, can not suppress the slag growing amount with the same level of solid core welding wire, be owing to the component of weld wire that does not fully understand the reason that becomes the slag growing amount.The technology that in the past suppresses the slag growing amount in the technology, have pack completeness far below 10% technology (for example is controlled at, the spy opens that 2001-179488 communique, spy are opened the 2001-207087 communique, the spy opens the 2003-94196 communique), though can expect corresponding effects, but the adjustment amount of the component of weld wire of this method is limited, and the quantity of slag is not reduced to the degree of solid core welding wire.In pack completeness is that spy more than 10% opens in the technology that the 2000-197991 communique proposed, and is the assurance of relation of the quantity of slag that generates of amount and the welding back of oxide and insufficient, the therefore quantity of slag that takes place far more than solid core welding wire to the slag ingredient that contains in the solder flux.

For the problem of the quantity of slag that is reduced to the solid core welding wire level, adopt following method to solve in the present invention.

That is, the 1st kind of method is the SiO that solder flux contained that will exist in the welding wire ₂, K ₂O, Na ₂O, Al ₂O ₃Deng oxide do one's utmost to be reduced to method with the low slag of solid core welding wire par.The 2nd kind of method is by using graphite or SiC and using these two to solve as requested owing to reduce the method that the hot candied resistance of the caused welding wire of oxide in the solder flux increases.And the 3rd kind of method is to form CO or CO by carbon among graphite or the SiC and oxygen are reacted ₂Thereby make the method for oxygen evolution outside the weld metal zone in the source that generates as slag.

The 1st kind of method at first is described.

The slag ingredient that the present inventor at first forms the welding bead surface is implemented to analyze.And find that they are nearly all formed by oxide.And consider if reduce the oxide that exists in the solder flux of steel crust inboard, then can suppress the generation of slag, in fact carry out the welding wire of such composition design, find the slag growing amount seldom.As the reason of not carrying out the design of such component of weld wire up to now, be because due to the relation of the slag growing amount after the oxide in the solder flux and the welding it be unclear that.The present inventor is clear and definite to this point, thereby has finished the invention of the few metallic flux cored wire of slag generating capacity.

Next illustrates the 2nd kind of method.

Though found above-mentioned the 1st kind of method, only reduce the oxide in the welding wire, the problem that the hot candied resistance of welding wire increases can take place.That is, the problem that can cause fracture of wire in the welding wire manufacturing, especially in wire drawing takes place.This be since add oxide in the solder flux to and have the flowability that improves solder flux, will suppress the resistance of welding wire wire drawing lower effect.That is, oxide plays the effect of lubricant.Therefore, present inventors do not take to reduce oxide, thereby but take to add in the solder flux this is compensated having the graphite of effect of same lubricant or SiC or the two with oxide.That is, graphite is the same with oxide in SiC and the solder flux to have the effect that the flowability that makes solder flux increases, reduces the hot candied resistance of welding wire, therefore it is used.

Next illustrates the 3rd kind of method.

As described in the 1st kind of method, the slag that forms on the welding bead nearly all is an oxide.Therefore, reduce comparatively ideal of oxygen amount as far as possible.The 1st kind of method is the method that reduces the oxide in the solder flux, in addition, as the 3rd kind of method, adopts the C that makes in the welding wire and oxygen generation chemical reaction and with CO or CO in the present invention ₂Form be discharged into the method for the outside of weld metal zone.Because CO or CO ₂Be gas, can be discharged into the outside, weld metal zone, can not form slag, therefore can expect to reduce the effect of slag by the effect that reduces oxygen even therefore be formed also.

It more than is the method for reduction slag of the present invention.

Secondly, the basis of narrating welding wire of the present invention is graphite and SiC.

For the present invention, graphite and SiC are the effects that utilized the lubricant that suppresses the resistance in the welding wire wire drawing, make the oxygen with CO or CO with the oxygen reaction ₂Form be discharged into the weld metal zone the outside effect and guarantee that C in the weld metal becomes the composition of these effects of effect of component, its technical background is identical.But they have feature separately, and those skilled in the art considers that its feature can be judged and is to use the welding wire that adds graphite, also is to use the welding wire that adds SiC or use and add the welding wire of these two simultaneously.

Graphite is the composition that has only C, and C is a composition easily for control.On the other hand, SiC is the form of also adding Si except C, if therefore only from the viewpoint of composition design, graphite is more convenient for utilizing.But the particle of graphite is tiny, the problem that can occur dispersing in the solder flux adjustment.Not producing the production equipment that disperses, is not impossible according to existing technology, but has the problem that increases cost of investment.On the other hand, the problem that SiC exists is: compare with graphite that to have added unnecessary element be Si, the tendency littler than graphite as lubricant existence effect, that addition is Duoed than graphite etc.Those skilled in the art can consider their characteristics and select component of weld wire.

There is the effect of the C that increases weld metal in the interpolation of graphite and SiC, and it has the effect that makes the joint deterioration in characteristics.But present inventors find that the C amount beguine in the actual weld metal is low according to the C amount that the addition to welding wire pushes away in the weld metal that goes out.Its reason can think that C and oxygen react with CO or CO ₂Form and d/d cause.

At this, at first further describe the effect of graphite.

Fig. 1 and Fig. 2 are the schematic diagrames of this effect of expression graphite.Fig. 1 is that transverse axis is that quantity of graphite, the longitudinal axis in the welding wire is the coordinate diagram of the quantity of slag that generates of oxide amount in the welding wire and welding back.

Among Fig. 1, be represented by dotted lines the relation of quantity of graphite and oxide amount, represent the relation of the quantity of graphite and the quantity of slag with solid line.In the upper-side area of dotted line is that the manufacturing efficient of welding wire does not have the zone that descends, can know from the dotted line of Fig. 1, when graphite is increased, can make the undiminished situation decline of efficient protoxide at welding wire.It is good that oxide reduces from the viewpoint that suppresses the slag generation, therefore can see the additive effect of graphite.

The solid line of Fig. 1 is represented the relation of the quantity of slag that quantity of graphite and welding back generate.What the solid line of Fig. 1 was represented thes contents are as follows.That is, add (A of Fig. 1) after a certain quantity of graphite, can determine welding wire to make the oxide amount (B of Fig. 1) of the minimum that efficient do not reduce according to dotted line.And the slag generating capacity (C of Fig. 1) when adopting the welding wire welding that contains this quantity of graphite and oxide amount is represented with solid line.Therefore,,, then can not become the quantity of slag shown in the solid line, and take place than its slag of volume more if do not reduce oxide amount (for example quantity of graphite shown in the D of Fig. 1 and oxide amount) even only add the graphite of the amount shown in the A of Fig. 1.The effectiveness that graphite adds is: can be lowered into the oxide amount (till the amount shown in the solid line of Fig. 1) of the reason of the slagging of making a living and do not reduce welding wire and make efficient.

But the interpolation that Fig. 1 expresses graphite has than its bigger effect.In the few zone of graphite addition, the solid line of Fig. 1 is consistent basically with dotted line, but the graphite addition for a long time, and solid line is positioned at the more position of below.That is, mean to have than reducing the bigger effect of oxide.This phenomenon be because: graphite is that C combines with oxygen, becomes CO or CO ₂, reduce the oxygen amount, so the result can suppress the generation that slag is an oxide.

Such as previously discussed, graphite has several advantages, but the reason that is not utilized so far is: exist from the excessive impression of the mechanical property unfavorable factor of welding point.Therefore, the interpolation of graphite is so far just attempted under the situation of minute quantity.The present inventor proposed to doubt to former general knowledge.Promptly can think, increase even added the C amount of the welding wire of graphite, as the weld metal composition after in fact welding, if consider that C is with CO, CO ₂Form be discharged into the outer possibility of welding bead, then can not become such high C.

At this, the present inventor has investigated the relation of adding the C composition in quantity of graphite and the weld metal test.Fig. 2 is its result's of expression figure.Among Fig. 2, transverse axis represents that the quantity of graphite (the quality % all to welding wire), the longitudinal axis that add in the solder flux represent the C amount (quality %) in the weld metal test.And it is the situation of 0.05% metallic flux cored wire of all quality of welding wire as welding wire that Fig. 2 is to use C content in the steel crust.And the quantity of graphite that transverse axis is represented is represented the quantity of graphite that whole flux-cored wires contain.Know from Fig. 2, even for example add 0.4% graphite, as weld metal composition also less than 0.2%.The C amount of this degree the bad of joint mechanical performance can not occur especially.On the other hand, when the graphite addition greater than 0.7% the time, be more than 0.40% as the C amount of weld metal composition, surpass 0.5% in some cases, might exert an influence to mechanical performance.Therefore, in the present invention, for metallic flux cored wire, at least the addition of the graphite that contains as solder flux on to be limited to 0.7% be necessary.This reason is by making graphite addition less than 0.7%, can keep good welding wire to make efficient and reduces oxide in the welding wire, and the slag generating capacity when its result makes welding fully reduces, and the C content that suppresses simultaneously in the weld metal sharply increases.

In Fig. 2, even the addition of graphite is 0 but C in weld metal amount is not 0 yet, this is owing to contain the cause of C in the steel crust.

Secondly, the effect with regard to SiC describes in more detail.

About the interpolation of SiC, the possibility that exists the C that makes in the weld metal to increase, make the problem of joint deterioration in characteristics to take place.At this, the present inventor has investigated the relation that the addition of SiC in the solder flux and C in weld metal amount and Si are measured.It the results are shown in Fig. 3.Fig. 3 is that transverse axis represents that SiC addition (addition that accounts for welding wire full weight amount is represented with %), the longitudinal axis represent the C amount in the weld metal and the coordinate diagram of Si amount.Even the SiC addition is that 0 o'clock C and Si in the weld metal is not 0 yet, this is because contain 0.05%C and 0.2%Si in the steel crust.Know that from Fig. 3 the C in the weld metal that the C beguine that exists in the actual weld metal calculates according to the C in the welding wire is low.Even this means and add SiC in welding wire, the same with the situation of graphite, the C among the SiC not necessarily imports in the weld metal fully.Can think that promptly C combines with CO or CO with oxygen ₂Form be discharged into outside the welding seam part.So, in the present invention, do not take to reduce the oxide in the solder flux but the method for adopt adding SiC, reached the reduction of the quantity of slag.In Fig. 3, express the Si amount in the weld metal.When adding SiC in welding wire, not only C is imported into weld metal, and Si also is imported into weld metal, but the amount that imports, Si is more than C.In composition of the present invention system, in the composition system based on SiC, as described later, the upper limit of SiC is limited in 1.2% especially, and its reason is the Si surplus in the weld metal.

The 2nd kind of method that reduces slag of the present invention, utilized the C among the SiC combine with oxygen, with CO or CO ₂Form be discharged into outside effect.This phenomenon prevents that not only the C in the weld metal from significantly increasing, and also has the effect that reduces the oxygen composition, therefore, consequently can suppress the generation of slag.That is, to add SiC be the effect by reducing the addition of oxide in the welding wire whereby and make oxygen be discharged into outside these 2 effects with gas componant to bring into play the method that subtracts the slag effect.

Fig. 4 is the coordinate diagram that addition, the longitudinal axis that transverse axis is represented SiC are represented the oxide amount in the solder flux in slag growing amount and the welding wire.Among Fig. 4, the SiC amount dots with the relation of oxide amount, the SiC amount is represented with solid line with the relation of the quantity of slag.There is good dependency relation in slag growing amount after oxide in the solder flux and the welding, therefore, although the iron scale difference can be illustrated on the same longitudinal axis.The upper-side area of dotted line is that welding wire is made the zone that efficient does not reduce, and from the dotted line of Fig. 4 as can be known, when SiC is increased, can make the state decline protoxide amount of efficient not reducing welding wire.If the reduction oxide amount then can reduce the quantity of slag, be appreciated that the validity that SiC adds.

For example, when adding a certain amount of SiC (A of Fig. 4), can determine can not reduce the minimum oxide amount (B of Fig. 4) that welding wire is made efficient according to dotted line.And the slag generating capacity (C of Fig. 4) when adopting the welding wire that contains this SiC amount and oxide amount to weld is represented with solid line.Therefore,,, then can not become the quantity of slag shown in the solid line, occur in its above quantity of slag if oxide amount does not reduce (for example amount of the SiC shown in the D of Fig. 3 and oxide amount) even when only adding SiC with the amount shown in the A of Fig. 1.The effect of adding SiC is, can reduce the oxide amount (up to the amount shown in Fig. 4 solid line) that becomes slag generation reason and the manufacturing efficient that does not reduce welding wire.The reduction of oxide is preferred from the viewpoint that suppresses the slag generation, this shows the effect of adding SiC.

But Fig. 4 is same as in figure 1, demonstrates interpolation SiC and has than its bigger effect.In the few zone of SiC addition, dotted line and the solid line of Fig. 4 are unanimous on the whole, but at the SiC addition for a long time, solid line is in the more position of below.That is, mean to have the effect that reduces more than the oxide.The generation of this phenomenon is because C and oxygen among the SiC are combined into CO or CO ₂, because the reduction of oxygen amount, so the result can suppress the generation that slag is an oxide.

As mentioned above, in the present invention, by having used 3 kinds of methods of graphite and SiC, the slag growing amount after might realizing welding reduces to the metallic flux cored wire with the same level of solid core welding wire.

Secondly, numerical definiteness reason of the present invention is described.

At first, the numerical definiteness reason of each the composition element in the metallic flux cored wire is narrated.

The welding wire of 2 kinds of composition systems has been proposed in the present invention.That is be these 2 kinds as composition system that must composition and with SiC as composition that must composition, with graphite.In the present invention, these composition systems are called " graphite composition series solder wire " and " SiC composition series solder wire ".

At first, with regard to graphite composition system its numerical definiteness reason of narration.

About beyond the graphite and the C beyond the SiC, in quality %, its lower limit is restricted to 0.001% as the C amount that accounts for whole welding wire.Do not reach the C amount of this lower limit, be difficult to guarantee the intensity of steel crust, cause the fracture of wire problem when making welding wire, so lower limit is defined as this value.And, beyond the graphite and the upper limit of the C beyond the SiC be defined as 0.20%, this is because when the C that is higher than this value measures, in metallic flux cored wire of the present invention, owing in solder flux, add graphite separately, so the C of weld metal amount too much, so its upper limit is defined as 0.20%.

And as beyond the graphite and the C beyond the SiC, the iron powder that is added in the solder flux also can contain C.In this case, consider the sclerosis when welding wire is hot candied, preferably the C with the steel crust is set at below 0.15%, and remainder is replenished by the C in the iron powder.

The reason of adding graphite in the present invention is: make the effect of its lubricant of bringing into play solder flux and form CO, CO by reacting with oxygen ₂And oxygen evolution is arrived outside.These reasons are to have aimed at the target that the quantity of slag is reduced, and effect in addition also is in order to make it have effect as the high-fatigue strength welding material, the suitable C amount that keeps weld metal, control starting temperature of transformation lower.

One of purpose of the present invention is to guarantee coating, and this is can list automotive field as the field that utilizes of the present invention.The C amount of the steel plate that uses in this field is lower as a rule, is below 0.05%, under some situation even be below 0.01% sometimes.In this case, be difficult to keep the C amount in the weld metal when also considering the mother metal dilution suitable.This C amount also can import from the steel crust, but by make contain in the welding wire that graphite can obtain that the quantity of slag reduces and the effect of lubricant these two, therefore the upper limit of in the present invention C of steel crust being measured is controlled lowly.At this moment, require minimally to add graphite.The minimum of the C amount of the lower limit of graphite of the present invention from guarantee weld metal and guarantee that the quantity of slag reduces and these 2 reasons of effect of lubricant is defined as 0.10%.

On be limited to 0.7%, be because surpassing the quantity of graphite of this amount will increase the C amount of weld metal, the weld metal problem of joint characteristic such as really up to the mark that becomes takes place, so be set at this value.And for the effect of the lubricant that plays graphite conscientiously, preferred graphite lower limit set is 0.15% to be advisable.

Si in the welding wire can be divided into the SiO of oxide form ₂, and SiC and Si in addition, SiO ₂Mainly be contained in the solder flux with SiC.The Si that contains in the steel crust nearly all is the Si of solid solution in steel, in the present invention, and the SiO in the steel ₂It is unavoidable impurities.The SiO that contains in the solder flux ₂Deng oxide, except mica, in employed binding agent when being filled in solder flux in the welding wire and carrying out granulation, also contain, though be metal system, as long as with flux-cored wire as prerequisite, then must add binding agent.Therefore, as described later, stipulate the total amount of oxide in the present invention.But, except SiO ₂Si in addition owing to do not contain the aerobic composition, therefore from generating the viewpoint of slag, then need not limit too much.But, owing to require MIN deoxidation, so lower limit is defined as 0.05%.On the other hand, excessive interpolation Si.Unsatisfactory from the viewpoint that makes weld metal sclerosis and joint characteristic, so the upper limit is defined as 1.2%.

Mn is an element of guaranteeing intensity necessity, and the following of Mn is limited to 0.2%, is being lower than the intensity that is difficult to guarantee weld metal under the situation of this amount, therefore is set at this value.On the other hand, when its addition is too much, can cause the deterioration of weld metal toughness, so its upper limit is defined as 3.0%.

P and S are the unavoidable impurities elements, and in the present invention, there is its toughness deterioration more for a long time in these elements, so the upper limit of the content of P and S is defined as 0.03% and 0.02% respectively.

SiO ₂, Al ₂O ₃, Na ₂O and K ₂O is called as the slag agent, and the reason of adding them is: before making metallic flux cored wire, play the effect of binding agent when flux constituent is carried out granulation; And after being filled to the steel iron sheet, pull in the hot candied operation of regulation gage of wire, play the lubrication of minimizing solder flux resistance etc.Even for the solder flux content in the welding wire, the granulating working procedure of solder flux is to make the indispensable operation of metallic flux cored wire of high-quality.On the other hand, as the effect of lubricant, make graphite have this effect in the present invention, the reason of therefore adding these oxides mainly is the granulation for solder flux.But they all are oxides, from reducing this viewpoint of slag growing amount, do not add comparatively desirable.,, the granulation of solder flux can not be carried out, therefore MIN addition must be added if there are not these compositions.Under be limited to 0.05%, can not obtain above-mentioned effect being lower than at 0.05% o'clock, and the welding wire quality take place and make problem on the efficient, therefore be set at this value.On be limited to 0.40%, when surpassing the addition of this amount, the slag generating capacity after the welding increases, and produces the problem of coating, therefore is set at this value.

In the graphite composition series solder wire of the present invention, can add SiC as requested.In this case, about guaranteeing the C in the weld metal or reduce resistance in the welding wire wire drawing, owing to added graphite, therefore there is no need to resemble and add the SiC composition described later system.The lower limit set of SiC addition is 0.05%, and it is restricted to by adding SiC can demonstrate the MIN value that fatigue strength improves and reduces quantity of slag effect.On the other hand, on be limited to 0.6%, when the addition that surpasses 0.6%, owing to fully added graphite, so the amount of the C in the weld metal is undue improves, and can cause the joint toughness deterioration, therefore is set at this value.

For the present invention, Ni, Cr, Mo, Cu are the elements that mainly adds so that the tensile strength of welding point or fatigue strength rise to purpose.These elements can be selected its addition according to the application target of welding material.By adding these elements, intensity is increased, and fatigue strength is also increased by the starting temperature of transformation that reduces weld metal.Yet though the effect of these elements is identical, the effect of every interpolation 1% is not necessarily identical, therefore each element is determined scope.

Ni is the element that reduces starting temperature of transformation, joint characteristics such as intensity and toughness are improved.The lower limit of Ni determines 0.5%, is the MIN value that obtains intensity and toughness raising by interpolation.On be limited to 12.0%, surpass the interpolation of this amount, might make weld metal not undergo phase transition and be cooled to finally with austenitic state, can not expect the raising of fatigue strength, so higher limit is defined as this value.

Cr and Mo are the element that adds in order to improve weld metal intensity and quenching degree in the present invention.For the fatigue strength that makes welding point improves, the low tissues of phase transition temperature such as formation martensite are necessary.Therefore, guarantee that quenching degree is indispensable.Cr and Mo are the elements by adding easy raising intensity and guaranteeing quenching degree.So as obtaining the MIN value that intensity improves and guarantees the effect of toughness, the lower limit of setting Cr and Mo element is 0.1%.On the other hand, Cr and Mo are the same with Ni, can reduce starting temperature of transformation by adding, but different again with Ni, and be from the viewpoint of the toughness that improves weld metal, good not as adding Ni.So it is necessary that the upper limit of Cr and Mo element is lower than Ni.The upper limit of these elements is set to 3.0%, because surpass the interpolation of this amount, the problem on the characteristic of joint can take place, and therefore is set at this value.

Cu is also the same with Cr, Mo, is the effective elements that reduces starting temperature of transformation, improves intensity and guarantee quenching degree.But, when addition is too much, exist to make weld metal that the Cu risk of crack take place, thus higher limit set than Cr or Mo lower be necessary.On be limited to 0.5%, set in order not produce the Cu crackle.On the other hand, Cu also may mainly use in order to ensure electric conductivity by the welding wire coating, and the lower limit set of Cu is 0.1%, from improving intensity and improving the effect of quenching degree and the viewpoint of guaranteeing electric conductivity, is the MIN value that needs.

In the present invention, the total amount of these 4 kinds of element Ni, Cr, Mo, Cu also is provided with restriction, these elements have and reduce starting temperature of transformation, improve intensity and guarantee the effect of quenching degree, act on identical.But if these elements too much add, weld structure can become austenite structure, and promptly the cooling procedure after the welding does not undergo phase transition, and does not therefore improve the effect of fatigue strength.And, under the few situation of addition, can not expect to obtain the effect that tensile strength improves.So, be necessary to limit the total of these elements.Under be limited to 0.2%, be lower than the addition of this amount, the effect that can not expectation strength increases is so be set at this value.On be limited to 12.5%, surpass the addition of this amount, weld metal becomes the tissue based on austenite, the phase change expansion of the cooling procedure in the welding is insufficient, can not expect the effect that fatigue strength improves, and therefore is set at this value.The purpose of adding these elements is under the situation that improves tensile strength, and the upper limit of addition is set at 4.0%, and is with Nb and V and the usefulness that aftermentioned is added, comparatively desirable economically.And, be under the situation of purpose at fatigue strength with the raising welding point, the lower limit of the total addition of these 4 kinds of element Ni, Cr, Mo, Cu is preferably set to 2.0%.This is because addition is lower than under the situation of this value the cause that the starting temperature of transformation of weld metal does not reduce, makes fatigue strength to be difficult to improve.For fatigue strength is improved, this lower limit is preferably set to 3.0%.

B is the element that improves quenching degree, and in order to ensure the quenching degree of steel plate, the interpolation of B is just enough in weight % interpolation about 0.001%, but under the situation of weld metal, the oxygen amount is higher than steel plate, and B combines with oxygen and seizes its effect, is necessary than the interpolation of Duoing under the situation of steel plate therefore.The reason of guaranteeing quenching degree is: make the microscopic structure of weld metal become more high-intensity tissue; Suppress the appearance of the tissue that phase transformation begins under the high temperature and become the microscopic structure etc. of phase transformation under low temperature more.These effects are from guaranteeing tensile strength, guaranteeing that this two aspect of fatigue strength is preferred, therefore it is considered herein that and actively utilize.As the MIN value of the quenching degree that can improve weld metal, the lower limit set of the addition of B is 0.001%.About the upper limit of B addition, even add the amount that surpasses this value, the effect that interpolation B obtains does not increase yet, and therefore is defined as 0.03%.

Nb, V, Ti all can form the element that carbide has the effect of the intensity of making increase, can expect with less addition intensity to be increased.That is, for the present invention, these 3 kinds of elements are the elements that can expect same effect.Therefore, limit the total of these elements in the present invention.Under be limited to 0.005%, the addition that is lower than this amount less can increase by expectation strength, therefore is set at this value.On the other hand, when the addition that surpasses 0.3%, the intensity of weld metal is too high, can produce the problem of joint characteristic aspect, so the upper limit is defined as 0.3%.Therefore in addition, about Ti, except gaining in strength, also have the effect that makes welding arc stablility, the lower limit set of preferred Ti content is 0.003% to be advisable.

Arc stabilizer is by its interpolation being made the element of welding arc stablility, and is of the present invention

(1) described Na ₂O or K ₂O etc. also have the effect that makes arc stability, therefore claim that they are that also it doesn't matter for arc stabilizer.Therefore, for the present invention, there is no need to add their arc stabilizers in addition, in addition, when adding these arc stabilizers, existence can not reach the danger that promptly reduces the quantity of slag as the 1st purpose of the present invention.But, if the compound of Na, Al, F then has the effect that makes arc stability, with Na ₂O and K ₂There is ice crystal (Na in the O difference ₃AlF ₆) wait and so on oxide based beyond material.If the material beyond the oxide can not become the oxygen supply source even then add in the welding wire yet, therefore can not generate the slag that forms by oxide, be possible according to desiring to make the more stable requirement of electric arc add these arc stabilizers.So the possible applicable scope that oxide based arc stabilizer in addition of the present invention is set has its meaning.The lower limit set of the arc stabilizer beyond oxide based is 0.05%, is the MIN value that obtains the arc stability effect by interpolation.On the other hand, on be limited to 0.5% because oxide based slag agent is added as binding agent, these elements also have the effect of arc stabilizer, add even therefore surpass this amount, effect does not change yet, so the upper limit is defined as 0.5%.

More than, be that the composition of the graphite composition series solder wire of metallic flux cored wire of the present invention limits reason.

Secondly, the composition of narration SiC composition series solder wire limits reason.

Beyond the graphite and the C beyond the SiC be the C that for example adds from the steel crust.C from the weld metal that either party of steel crust, graphite, SiC imports, its effect all is identical.But effective to preventing fracture of wire in the hot candied operation of the C in the steel crust in making welding wire, it is necessary therefore it being defined in suitable scope.For beyond the graphite and the C beyond the SiC, its lower limit set is 0.01%, and its reason is because during this amount of C quantity not sufficient in the steel crust, big to the influence of welding wire fracture of wire, the cost of welding wire itself increases considerably, and can not make the cause of welding point economically.On the other hand, in the steel crust, during excessive interpolation C, in wire drawing, harden specifically, so the upper limit is set at 0.20%.And, as beyond the graphite and the C beyond the SiC, may contain C by the iron powder in adding solder flux to.In this case, consider the sclerosis of welding wire in wire drawing, the C in the steel crust is set at below 0.15%, and remainder is replenished by the C in the iron powder and is advisable.And beyond the graphite and the lower limit of the C beyond the SiC, system sets higherly than graphite composition, and this is because the effect of the lubricant of SiC is lower than the cause of graphite.

About the addition of SiC, lower limit is defined as 0.6%, the upper limit is defined as 1.2%.The welding wire of SiC composition system mainly relies on the C among the SiC to reach the reduction of the starting temperature of transformation of weld metal, therefore sets this value in order to ensure MIN C amount.About its lower limit, be set at the MIN value that to expect to improve fatigue strength.If 1.2% of the interpolation upper limit SiC in welding wire, then as shown in Figure 3, in weld metal, not only import C but also importing Si, when being higher than the addition of this value, except SiC, can be superimposed with the Si that in welding wire, has added, then can not guarantee the impact characteristics of weld metal zone, and produce the sclerosis problem of weld metal or austenite structure become many and do not have phase transformation, so can not expect the problem of fatigue strength raising etc., so be set at this value.

In order to obtain the MIN deoxidation effect in the arc welding, beyond the SiC and SiO ₂The lower limit of Si in addition is defined as 0.05%.And good and obtain good weld bead shape for the compatibility that makes fusion pool and steel plate, the Si amount is preferably more than 0.1%.On the other hand, excessive interpolation can make the weld metal sclerosis, and is unsatisfactory from the viewpoint of joint characteristic, so its upper limit is defined as 1.2%.

Mn guarantees the necessary element of intensity.The following of Mn is limited to 0.2%, because be lower than under the situation of this amount, is difficult to guarantee weld metal intensity, so be set at this value.On the other hand, when its addition is too much, can cause the deterioration of the toughness of weld metal, so its upper limit is defined as 3.0%.

P and S are the unavoidable impurities elements, in the present invention, when these elements exist in weld metal in a large number, its toughness deterioration, so the upper limit of the content of P and S is defined as 0.03% and 0.02% respectively.

The SiO that adds in the solder flux ₂, Al ₂O ₃, Na ₂O and K ₂O is called as the slag agent, and the reason of adding them is: play the effect of binding agent when before the metallic flux cored wire manufacturing flux constituent being carried out granulation; And after being filled to the steel iron sheet, pull in the hot candied operation of regulation gage of wire, play the lubrication of the resistance that reduces solder flux etc.Under be limited to 0.05%, when being lower than this value, can not obtain above-mentioned effect, the welding wire quality can take place and make problem on the efficient, therefore be set at this value.On be limited to 0.40%, under the situation of the addition that surpasses this amount, the slag generating capacity after the welding increases, and produces the problem of coating, therefore is set at this value.

For SiC composition system, can add graphite as requested.The interpolation of graphite not only helps the reduction of the starting temperature of transformation of weld metal, and has the effect that is suppressed in the welding wire wire drawing from the resistance of solder flux, therefore can improve welding wire and makes efficient by adding graphite.But,, on the basis of these problems of consideration, can select whether in solder flux, to add graphite owing to there is the problem of dispersing in adding solder flux to the time.The lower limit set of graphite addition is 0.05%.This value is can expect to make the MIN value of the effect that the fatigue strength of welding point improves by adding graphite.On be limited to 0.4%, in SiC composition system, owing to mainly reach the reduction of the starting temperature of transformation of weld metal by SiC, therefore the addition that is higher than this value, can produce that the sclerosis problem of weld metal or austenite structure increase and can not phase transformation and can not expect problem such as fatigue strength raising, so be set at this value.

The welding wire that SiC composition of the present invention is can also add Ni, Cr, Mo, Cu as requested.

Ni is for the starting temperature of transformation that reduces weld metal, reaches joint fatigue strength and improve necessary element.And be the element that joint characteristics such as intensity and toughness are improved.The following of Ni is limited to 0.5%, is definite as expecting minimum that fatigue strength improves.On be limited to 5.0%, in SiC composition series solder wire, reached the significantly reduction of starting temperature of transformation by C, the interpolation of this amount of surpassing, interact with the C amount of having added, might make weld metal not undergo phase transition and be cooled to finally, can not expect the raising of fatigue strength, therefore it is defined as this value with austenitic state.

Cr and Mo are for the starting temperature of transformation that reduces weld metal in the present invention and improve weld metal intensity and quenching degree and the element that adds.For the fatigue strength that makes welding point improves, the low tissues of phase transition temperature such as formation martensite are necessary.For this reason, guarantee that quenching degree is indispensable.Cr and Mo are that this effect is bigger than Ni by the element that adds easy raising intensity and guarantee quenching degree.So as obtaining the MIN value that intensity improves and guarantees the effect of quenching degree, the lower limit of setting them is 0.1%.On the other hand, Cr and Mo are the same with Ni, can reduce starting temperature of transformation by adding, but different again with Ni, and be from the viewpoint of the toughness that improves weld metal, good not as adding Ni.And in the 1st composition system, C has reached the reduction of starting temperature of transformation certain degree, so the upper limit of these elements is set at 2.0%.

Cu is also the same with Cr, Mo, is to have the effective elements that reduces starting temperature of transformation, improves intensity and guarantee quenching degree.But, when addition is too much, exist to make weld metal that the Cu risk of crack take place, thus higher limit to set lowly than Cr or Mo be necessary.On be limited to 0.5%, set in order not produce the Cu risk of crack.On the other hand, Cu also might mainly use in order to ensure electric conductivity by the welding wire coating, and the lower limit set of Cu is 0.1%, from effect that intensity improves and quenching degree improves and the viewpoint composition of guaranteeing electric conductivity, is set at the value of the least restrictive that needs.

SiC composition series solder wire is provided with restriction to the total addition of Ni, Cr, Mo, Cu.These elements have and reduce starting temperature of transformation, improve intensity and guarantee the effect of quenching degree, and its effect is identical.But when these elements of too much interpolation, weld structure becomes austenite structure, and promptly the welding back does not undergo phase transition in cooling procedure, so the effect that fatigue strength improves disappears.On the other hand, addition more after a little while, the reduction of starting temperature of transformation is insufficient, can not expect the raising of fatigue strength.Therefore, the total of these elements also needs restriction.Under be limited to 0.5%, when being lower than the addition of this value, can not expect the effect that fatigue strength improves, therefore be set at this value.On be limited to 6.0%, owing to reached the reduction of starting temperature of transformation certain degree,, can make weld metal become tissue based on austenite so surpass the addition of this value by C, do not undergo phase transition itself and can not expect the raising of fatigue strength, therefore be set at this value.System compares with the graphite composition, and the reason that the upper limit of the total amount of these elements is suppressed lowlyer is: the effect as lubricant of SiC is not so good as graphite, therefore is set at the addition of Duoing than graphite, and the result can fully guarantee the C in the weld metal.

B is the element that improves quenching degree, and in order to ensure the quenching degree of steel plate, the interpolation of B is just enough in weight % interpolation about 0.001%, but under the situation of weld metal, the oxygen amount is than the height of steel plate, and B combines meeting and seizes its effect with oxygen, and therefore add is necessary more under the situation of steel plate.The reason of guaranteeing quenching degree is: make the microscopic structure of weld metal become more high-intensity tissue, suppress the generation of the tissue that phase transformation at high temperature begins and become microscopic structure of phase transformation under low temperature more etc.These effects are from guaranteeing tensile strength, guaranteeing that this two aspect of fatigue strength is preferred, therefore thinks in the present invention and must actively utilize.The lower limit of the addition of B, the MIN value as the quenching degree that can improve weld metal is set at 0.001%.About the upper limit of B addition, even add the amount that surpasses this value, the effect that is obtained by interpolation B does not increase yet, and therefore is defined as 0.020%.

Nb, V, Ti all can form the element that carbide has the effect of the intensity of making increase, can increase by expectation strength with less addition.That is, for the present invention, these 3 kinds of elements are the elements that can expect same effect.Therefore, limit the total of these elements in the present invention.Under be limited to 0.005%, the addition that is lower than this amount less can increase by expectation strength, therefore is set at this value.On the other hand, when the addition that surpasses 0.3%, then the intensity of weld metal is too high, can produce the problem of joint characteristic aspect, so the upper limit is defined as 0.3%.Therefore in addition, about Ti, except gaining in strength, also have the effect that makes welding arc stablility, the lower limit set of preferred Ti content is 0.003% to be advisable.

Arc stabilizer is by it being added on the element that makes welding arc become stable in the solder flux, the present invention (1), (4) described Na ₂O and K ₂O etc. also have the effect that makes arc stability, therefore claim that they are that also it doesn't matter for arc stabilizer.Therefore, for the present invention, it is not necessarily necessary to be added on its above arc stabilizer, and if add these arc stabilizers too much, then the reduction that is the quantity of slag as the 1st purpose of the present invention has the danger that can not reach.But, if the compound of Na, Al, F then has the effect that makes arc stability, with Na ₂O and K ₂There is ice crystal (Na in the O difference ₃AlF ₆) wait and so on oxide based beyond material.If the material beyond the oxide can not become the oxygen supply source even then add in the welding wire yet, therefore can not generate the slag that forms by oxide, be possible according to desiring to make the more stable requirement of electric arc add these arc stabilizers.So the possible scope of application that oxide based arc stabilizer in addition of the present invention is set has its meaning.The lower limit set of the arc stabilizer beyond oxide based is 0.05%, is the MIN value that obtains the arc stability effect by interpolation.On the other hand, on be limited to 0.5% because oxide based slag agent adds,, add even therefore surpass this amount because these elements also have the effect of arc stabilizer, effect does not change yet, so the upper limit is defined as 0.5%.

More than, be that the composition of SiC composition series solder wire of the present invention limits reason.

Secondly, the pack completeness of narration solder flux.

In the present invention, the pack completeness to the solder flux of graphite composition series solder wire limits.

Owing to can reduce slag growing amount after the welding by restriction flux constituent of filling in welding wire, therefore as long as in the scope of the pack completeness of common metallic flux cored wire, just can obtain its effect, and needn't open the 2001-179488 communique as the spy, the spy opens the 2001-287087 communique or the spy opens the 2003-94196 communique, reduces pack completeness consciously.And, under the low situation of the pack completeness of solder flux,, then also can give full play to its effect as long as component of weld wire is limited within the scope of the invention.Therefore, for the present invention, the scope of restriction solder flux pack completeness is under the many situations of the such alloying element addition of high-fatigue strength welding material.For example, the pack completeness of solder flux is defined as 5% welding wire, accounts under the 10% all situation of welding wire at the Ni addition, and it is inadequate only adding Ni in solder flux, must use the steel crust of the special use of having added Ni.In this case, can not use common steel crust, problem economically can take place.Problem such when pack completeness is very high can not take place.The lower limit of solder flux pack completeness is defined as 10%, is the free degree of fully guaranteeing the component of weld wire design, and sets as the scope that high strength welding material, high-fatigue strength welding material may reach.On be limited to 20%, surpassing under the situation of 20% pack completeness, the shared ratio of steel crust reduces in the welding wire, has the danger of fracture of wire in the welding wire manufacturing, therefore is set at this value.

And, in the present invention, pack completeness for the welding wire of SiC composition system is not done special restriction, this is because the lubricant of SiC is littler than the effect of the lubricant of graphite, addition is set highlyer, becoming the composition system that alloying element addition such as Ni correspondingly is suppressed, is 10% so there is no need as lower limit set.And, in order to realize the desired pack completeness of SiC composition series solder wire,, therefore there is not capping as long as just enough in the pack completeness scope of common flux-cored wire.

Secondly, narrate with regard to protective gas.

For gas-shield welding method,, use and contain 100%CO usually as protective gas ₂, or Ar gas in contain CO ₂The mist of gas.The preparation method that the purpose of this invention is to provide the few high-fatigue strength welding point of welding slag generating capacity considers that welding slag is SiO basically ₂Oxide based with MnO etc., for protective gas, be preferably and select the few gas of oxygen content.For this reason, in welding method of the present invention,, be defined as adopting Ar+3～25%CO as protective gas ₂Gas.And, CO ₂Gas is 0 o'clock, and therefore electric arc stable bad be defined as containing in the Ar gas CO more than 3% ₂Contain and surpass 25%CO ₂Ar gas, its slag generation aspect and 100%CO ₂Situation under substantially identical, so the upper limit is defined as 25%.

O in the protective gas ₂Gas is foreign gas for the present invention.But, in Ar gas, have O ₂Under the situation of gas, need remove O ₂Therefore the expense of gas does not contain O usually ₂The protective gas ratio of gas contains O ₂The protective gas price of gas is more expensive.So present inventors think clear and definite O ₂The scope of the permissible level of gas is significant, has therefore determined its permissible range.At O ₂Gas surpasses under 4% the situation, and the growing amount of slag increases inevitable, so O ₂The upper limit of gas is set at 4%.

Secondly, the thickness of slab and the armor plate strength of narration steel plate.

At first, narration limits the reason of the thickness of slab of steel plate.

The present invention is a purpose with the preparation method that the few high-fatigue strength welding point of the slag growing amount that is equivalent to the solid core welding wire level is provided.Especially reduce about the quantity of slag, even do not limit the thickness of slab of steel plate, as long as use the metallic flux cored wire in the scope of the present invention then may obtain its effect.But from making the viewpoint composition of high-fatigue strength welding point, the thickness of slab that limits steel plate is necessary.

The principle of raising fatigue strength of the present invention is: weld metal undergoes phase transition in cooling, utilizes the volumetric expansion of the weld metal that takes place at this moment, and the welding residual stress that makes fatigue become the position of problem reduces.At this moment, steel plate must be restrained the volumetric expansion of weld metal.That is,, generate compression stress, welding residual stress is reduced as its counter-force by restraining volumetric expansion.For this reason, it is necessary the thickness of slab of steel plate being set lower limit.On the other hand, in the present invention, add the spy and open the described such alloying element of flat 11-138290 communique, so the starting temperature of transformation of weld metal is low like that not as the spy opens the described welding material of flat 11-138290 communique.When the phase transformation end of weld metal, thermal contraction appears in weld metal in cooling procedure subsequently, although therefore specially introduce compression stress, has the possibility that becomes the tensile stress state once more.So, in this art, have the tendency of setting starting temperature of transformation low as far as possible.But, starting temperature of transformation is reduced, mean that the welding wire cost increases, unsatisfactory.At this, limit the upper limit of thickness of slab among the present invention, and reduce the element addition as far as possible.Its reason is: under the thin situation of thickness of slab, and compare under the thicker situation of thickness of slab, sweating heat is delivered to the back side of steel plate in the more early stage stage, therefore is not easy to take place tensile stress in the phase transformation of weld metal finishes the thermal contraction process of back generation.

Lower limit for thickness of slab of the present invention, under the situation of the not enough 1mm of thickness of slab, make joint even use the metallic flux cored wire in the scope of the present invention, fusion penetration to thickness of slab is deepened, even weld metal undergoes phase transition expansion, steel plate can not fully be restrained this expansion, therefore can not fully reduce residual stress.That is, can not expect the raising of fatigue strength.For this reason, from this viewpoint of high-fatigue strength joint, the lower limit set of thickness of slab is 1.0mm.On the other hand, the debatable industry of the coating of welding point is an automotive field, in fields such as shipbuildings, even there is welding slag in welding bead, too big problem can not take place yet.Usually, automotive field does not almost have thickness of slab to surpass the situation of 5mm, and needing the industry of such thickness of slab is the shipbuilding field.That is, can judge that the superiority on industry is less.And if thickness of slab increases, then such as described above, sweating heat is not easy to be penetrated into the steel plate back side, in the thermal contraction process after the phase transformation of weld metal finishes tensile stress takes place, and can not expect the effect that fatigue strength improves.Therefore, the upper limit of thickness of slab is set at 5.0mm.

Secondly, narration limits the reason of armor plate strength.

In the present invention, the reason that must limit steel plate thickness also is for the fatigue strength that makes welding point improves, and is under the situation of target reducing the quantity of slag, need not limit especially.

Using metallic flux cored wire provided by the invention to make under the situation that the fatigue strength of welding point improves, its realization means are to utilize the method for residual stress of control weld metal zone of the phase change expansion of weld metal.That is, steel plate restrain phase change expansion weld metal, make weld metal and steel plate both sides that the method for counter-force take place.Under the low situation of armor plate strength, this counter-force can not fully improve, and the result is that residual stress can not reduce.About weld metal, the interpolation of alloying element is abundant, therefore low intensive problem can not take place.Therefore, the lower limit of setting armor plate strength is necessary.The lower limit 440MPa of armor plate strength sets as the MIN value that obtains sufficient counter-force.On the other hand, the higher limit 980MPa of armor plate strength, in the weld metal composition within the scope of the invention, the higher limit of the intensity of weld metal itself is about 980MPa, even if use the steel plate that has than its above intensity, the intensity of joint is determined by weld metal, therefore thinks nonsensical in practicality, therefore is set in this value.

Embodiment

Below, embodiments of the invention are described.

Table 1 and table 2 have been represented the one-tenth score value of metallic flux cored wire.Table 1 has provided quality %, the pack completeness that is added on the composition in the welding wire.Each composition is the quality % that accounts for the welding wire gross mass.Table 2 expression is added on the composition that the steel crust among the composition of welding wire is contained.Each composition of table 2 also is to be expressed as the quality % that accounts for the welding wire gross mass.That is, the composition that the amount shown in the table 2 is just added from the steel crust, remainder are the amounts from the solder flux interpolation that is filled in the welding wire.The welding wire code name be W01, W16, W17, W19 be comparative example, W01 is identical with W11 except graphite, but the graphite outer composition that is the scope of the invention, W16, W17 are the examples that the slag agent surpasses scope of the present invention.Component of weld wire among the W19, identical with W14 except the slag agent, be to make the steel crust contain example under the situation of C in order to have identical C amount with W14.And the arc stabilizer in the table 1 is that the compound of Na, Al, F is ice crystal (Na ₃AlF ₆).At first investigate the manufacturing efficient of welding wire.

When making the welding wire of table 1, the welding wire except W01 does not have special fracture of wire and can make on making.But,,, therefore cause on the way in the mill and can not carry out the manufacturing of welding wire by fracture of wire owing to do not add graphite although the W01 of one of comparative example is identical with W11 except graphite.For comparative example W16, W17, though do not add graphite, the addition of slag agent is identical with welding wire in the past, does not therefore have special problem on making.

Secondly, as mechanical property, investigated the summer ratio that when adding C, can reflect problem and impacted the absorption energy.

About summer ratio impact absorption energy, having prepared thickness of slab is the 470MPa level steel of 3.2mm, implements I type groove and welds, and therefrom cutting thickness of slab is the 2V breach summer ratio impact test piece of 2.5mm.Setting thickness of slab is that 2.5mm is because main purpose of the present invention is to consider in the suitable cause of automotive field.The position, center at weld metal is determined according to the purpose that the welding properties of materials is investigated in the position of breach.Charpy-type test is 0 ℃ of enforcement.

Its result of table 1 expression.About the W01 welding wire,, therefore can not implement test owing to fracture of wire in welding wire is made.For welding wire W11～W18, W20, learn the summer than impacting to absorb and to surpass 20J to have enough joint characteristics.But about comparative example W19, owing to import C from the steel crust, so the C of weld metal increases, and charp impact value is 11J, lower than the situation of other welding wire.Full C amount in the welding wire of W19 welding wire is 0.58%, learns with W14 welding wire of the present invention to have same C amount.But, use the charp impact value of the joint of W14 welding wire to surpass 20J, though it is identical to get cicada C amount, very big-difference is arranged with the mechanical property under graphite situation of adding and the situation of adding from the steel crust.

Table 1

The welding wire code name	The slag agent					Arc stabilizer	Graphite	C ¹⁾	Si ²⁾	Mn	P	S	Cu、Ni、Cr、Mo					Nb、V、Ti				B	Pack completeness	Wire drawing ³⁾	Summer ratio ⁴⁾	Remarks
	The slag agent												Cu、Ni、Cr、Mo					Nb、V、Ti									SiO ₂	Na ₂O	Al ₂O ₃	K ₂O	Add up to	Cu	Ni	Cr	Mo	Add up to	Nb	V	Ti	Add up to
	W01	0.20	0.05	0	0								0.25	0	0	0.05	0.50	2.0	0.01	0.005	0.2						SiO ₂	Na ₂O	Al ₂O ₃	K ₂O	Add up to	Cu	Ni	Cr	Mo	Add up to	Nb	V	Ti	Add up to	5.0	0	0	5.2	0.01	0.02	0	0.03	0	16	×	-	Comparative example (graphite)
W11	W01	0.20	0.05	0	0	0.20	0.05	0	0	0.25	0	0.25	0.25	0	0	0.05	0.50	2.0	0.01	0.005	0.2	0 05	0.50	2.0	0.015	0.007	0.2	5.0	0	0	5.2	0.01	0.02	0	0.03	0	16	○	26	Example of the present invention	5.0	0	0	5.2	0.01	0.02	0	0.03	0	16	×	-	Comparative example (graphite)
W11	W12	0.20	0.05	0	0	0.20	0.05	0	0	0.25	0	0.25	0.25	0.06	0.25	0.05	0.20	2.0	0.01	0.005	0.2	0 05	0.50	2.0	0.015	0.007	0.2	5.0	0	0	5.2	0.01	0.02	0	0.03	0	16	○	26	Example of the present invention	5.0	0	0	5.2	0	0	0.01	0.01	0.022	12	○	24	Example of the present invention
W13	W12	0.20	0.05	0	0	0.20	0.05	0	0	0.25	0	0.40	0.25	0.06	0.25	0.05	0.20	2.0	0.01	0.005	0.2	0.18	0.20	2.8	0.008	0.009	0.2	2.0	0.5	0.5	3.2	0	0	0	0	0	12	○	23	Example of the present invention	5.0	0	0	5.2	0	0	0.01	0.01	0.022	12	○	24	Example of the present invention
W13	W14	0.20	0.05	0	0	0.20	0.05	0	0	0.25	0	0.40	0.25	0	0.40	0.18	0.20	2.8	0.01	0.006	0.2	0.18	0.20	2.8	0.008	0.009	0.2	2.0	0.5	0.5	3.2	0	0	0	0	0	12	○	23	Example of the present invention	2.0	0.5	0.5	3.2	0	0	0	0	0.012	12	○	21	Example of the present invention
W15	W14	0.20	0.05	0	0	0.15	0.05	0.05	0.05	0.30	0.07	0.12	0.25	0	0.40	0.18	0.20	2.8	0.01	0.006	0.2	0.02	0.70	0.5	0.007	0.01	0.2	10.0	0.5	0	10.7	0	0	0	0	0	15	○	22	Example of the present invention	2.0	0.5	0.5	3.2	0	0	0	0	0.012	12	○	21	Example of the present invention
W15	W16	0.50	0.06	0.20	0.08	0.15	0.05	0.05	0.05	0.30	0.07	0.12	0.84	0	0	0.05	0 30	2.0	0.008	0.006	0	0.02	0.70	0.5	0.007	0.01	0.2	10.0	0.5	0	10.7	0	0	0	0	0	15	○	22	Example of the present invention	0	0	0	0	0.02	0	0.01	0.03	0	11	○	25	Comparative example (slag agent composition)
W17	W16	0.50	0.06	0.20	0.08	0.40	0.10	0.10	0.08	0.68	0.10	0.15	0.84	0	0	0.05	0 30	2.0	0.008	0.006	0	0.05	0.30	1.5	0.009	0.011	0.3	0	1.0	0.5	1.8	0	0	0	0	0	11	○	28	Comparative example (slag agent composition)	0	0	0	0	0.02	0	0.01	0.03	0	11	○	25	Comparative example (slag agent composition)
W17	W18	0.15	0.05	0.05	0.05	0.40	0.10	0.10	0.08	0.68	0.10	0.15	0.30	0.07	0.15	0.15	1.0	1.5	0.018	0.007	0.3	0.05	0.30	1.5	0.009	0.011	0.3	0	1.0	0.5	1.8	0	0	0	0	0	11	○	28	Comparative example (slag agent composition)	1.0	0	0	1.3	0.01	0	0.02	0.03	0	11	○	24	Example of the present invention
W19	W18	0.15	0.05	0.05	0.05	0.50	0.15	0.20	0.08	0.93	0	0	0.30	0.07	0.15	0.15	1.0	1.5	0.018	0.007	0.3	0.58	0.20	2.8	0.013	0.009	0.2	2.0	0.5	0.5	3.2	0	0	0	0	0.012	12	○	11	Comparative example (C beyond graphite, the graphite)	1.0	0	0	1.3	0.01	0	0.02	0.03	0	11	○	24	Example of the present invention
W19	W20	0.20	0.05	0	0	0.50	0.15	0.20	0.08	0.93	0	0	0.25	0	0.25	0.05	0.50	2.0	0.015	0.007	0	0.58	0.20	2.8	0.013	0.009	0.2	2.0	0.5	0.5	3.2	0	0	0	0	0.012	12	○	11	Comparative example (C beyond graphite, the graphite)	0	0	0	0	0	0	0	0	0	16	○	24	Example of the present invention

1) C beyond the expression graphite.2) expression SiO ₂Si in addition.

3) the hot candied process interruption silk during welding wire is made with * represent, do not have fracture of wire with zero expression.

4) thickness of slab is the 2V type breach Charpy-type test result of 2.5mm.Gap position is in the weld metal centre.

Table 2

The crust code name	C	Si	Mn	P	S	The welding wire name of using
The crust code name	C	Si	Mn	P	S	The welding wire name of using	S1	0.05	0.2	0.5	0.005	0.006	W01，W11，W12，W16，W17，W20
S2	0.18	0.2	0.5	0.006	0.005	W13，W14	S1	0.05	0.2	0.5	0.005	0.006	W01，W11，W12，W16，W17，W20
S2	0.18	0.2	0.5	0.006	0.005	W13，W14	S3	0.02	0.3	0.5	0.005	0.004	W15
S4	0.15	0.8	0.5	0.006	0.004	W18	S3	0.02	0.3	0.5	0.005	0.004	W15
S4	0.15	0.8	0.5	0.006	0.004	W18	S5	0.58	0.2	0.5	0.006	0.004	W19

Secondly, carry out the investigation of slag generating capacity.

In the welding wire of table 1, in making, welding wire the W01 of fracture of wire, use W11～W18 to carry out lap fillet welding.Assay method about the surperficial welding slag weight that takes place of welding bead, at first finish the back and be present in all weight of mensuration test piece under the surperficial state at welding slag in welding, remove welding slag then, measure all weight of test piece once more, determine the weight of welding slag by the difference of obtaining the two.It is certain 250mm that the test of implementing remains welding bead length, avoids the influence of welding bead length.The measurement result of the table 3 expression quantity of slag.Know that from the result of table 3 the welding slag amount among slag agent W11, W12, W13, W14, W15, W18 and the W20 within the scope of the invention all is lower than 0.1g, but under the situation of the W16, the W17 that use comparative example, the quantity of slag surpasses 0.3g.With the embodiment of table 1 respectively, using solid welding wire at 100%CO ₂Under the situation of protective gas and Ar+20%CO ₂When implementing same quantity of slag mensuration under the situation of gas, the slag generating capacity is respectively 0.09g and 0.05g, and the welding wire of example of the present invention can suppress to the slag growing amount same with solid core welding wire as can be known.

Know from above, welding wire W11, W12, W13, W14, W15, W18 and W20 in the scope of the present invention of control slag agent, it is no problem to make on the efficient at welding wire, it is also abundant that summer absorbs the mechanical property that can also demonstrate sufficient value, joint than impact, and slag generating capacity and solid core welding wire be par, can reduce the quantity of slag fully.

Table 3 has also been represented fatigue test results.At this moment, as steel plate, having prepared tensile strength is other 4 kinds of 270MPa, 470MPa, 570MPa and 780MPa levels.Table 3-has also represented the combination of welding wire and steel plate.

Test piece is shaped as being called as shown in Fig. 5 (a), Fig. 5 (b) " the lap fillet welding joint " shape.At first, make joint, implement fillet welding with the form of overlap joint steel plate 2 on steel plate 1.Then, carry out machining.The thickness of slab 3 of steel plate 1 and steel plate 2 and 4 is shown in Fig. 5 (a), Fig. 5 (b).The dashed area of Fig. 5 (a), Fig. 5 (b) is the weld metal part.

Fatigue test is implemented by direction of arrow P stress application shown in Fig. 5 (b).At this moment, fatigue crack occurs in the toe of weld end of fillet welding, propagates into steel plate 1 subsequently, with steel plate 1 disrumpent feelings form end takes place at last.That is, for this joint, the steel plate that fatigue crack takes place is meant steel plate 1.At present embodiment, the not necessarily same material of steel plate 1 and steel plate 2 also can be implemented test with the joint that has used different steel plates.And, because fatigue crack takes place steel plate 1, be near the welding bead of steel plate 1 in the toe of weld end, measure stress by pasting foil gauge.And, to apply loading repeatedly 2,000,000 times and not disrumpent feelings maximum stress is determined fatigue limit.

The welding wire that test number 1 uses is the W11 of table 1, in the scope of example of the present invention, is the few welding wire of the quantity of slag as component of weld wire therefore.But the intensity of steel plate 1 is outside scope of the present invention, so fatigue limit is 220MPa, is not extra high fatigue strength.On the other hand, in test number 2, the intensity that the steel plate 1 of fatigue crack takes place is 470MPa, and 2,000,000 fatigue limits are 360MPa, can realize high-fatigue strength.

On the other hand, test number the 3, the 4th, the situation of the not enough 1mm of the thickness of slab of steel plate, 2,000,000 fatigue limits are respectively 250 and 260MPa, are not high fatigue strength.This situation can be thought following reason: because the fusion penetration of welding bead is bigger with respect to thickness of slab, the phase change expansion that can not fully restrain weld metal can not reduce residual stress.In contrast to this, it is the above thickness of 1mm that test number 5 has thickness of slab, and 2,000,000 times fatigue limit is the high-fatigue strength of 380MPa.

The component of weld wire of test number 6 within the scope of the invention, the quantity of slag fully reduces, and the intensity height of the steel plate of fatigue crack takes place, therefore 2,000,000 times fatigue limit can reach the high-fatigue strength of 360MPa.Test number 12 is like this too.

The thickness of slab of the steel plate of test number 7,9,10,13 is more than the 1mm, and intensity also is more than the 470MPa, and component of weld wire also all within the scope of the invention, so 2,000,000 times fatigue limit of these joints is more than the 340MPa.Especially compare with the test number 9 that has used the W13 welding wire, used the test number 7 of the many welding wires of the total amount of Ni, Cr, Mo, Cu and 13 2,000,000 times fatigue limit to surpass 400MPa, the raising effect of fatigue strength is greater than test number 9.Therefore as can be known, to improve more effectively under the situation that fatigue strength is target, the alloying element addition is more comparatively desirable.On the other hand, test number 10 has used welding wire W14, and its component of weld wire is the composition roughly the same with test number 9, but has added B.In this case, the quenching degree of raising weld metal and the microscopic structure of phase transformation at low temperatures can be more than the situation of test numbering 9, therefore are the bigger examples of situation that fatigue strength improves effect ratio test numbering 9.Like this, in order to realize high-fatigue strength more effectively, it is comparatively desirable that the total amount of adding B and Ni, Cr, Mo, Cu such as sets morely at countermeasure.

In contrast to this, test number 8 and 11 be component of weld wire in extraneous situation of the present invention, 2,000,000 times fatigue limit is respectively 280MPa, 260MPa, does not reach 300MPa.

Test number 14～21st, the intensity of steel plate 1 is the embodiment under the more high-intensity 780MPa situation.Test number 14,16,17,18,20 is that thickness of slab surpasses all within the scope of the invention situations of 1mm and component of weld wire, the not enough 0.1g of the quantity of slag, and fatigue strength all realizes surpassing the example of the high-fatigue strength of 300MPa.In contrast to this, test number 15 and 19 is examples that the quantity of slag can not reduce and fatigue strength can not uprise.Test number 21 has used the W18 welding wire of table 1, therefore be example of the present invention, it is the example that the quantity of slag can fully reduce, but from the viewpoint that fatigue strength is improved, as shown in table 2, Cu, Ni, Cr, Mo add up to 1.3%, and low than W11, W12, W13, W14, W15 welding wire is that fatigue strength does not have the example that improves.Similarly, test number 23 is that the welding wire of use is the situation of W20 under the identical situation of the combination of steel plate 1 and steel plate 2 and test number 5.Therefore the armor plate strength of test number 23 and component of weld wire are the few situations of slag generating capacity all within the scope of the invention, but the same with test number 21, are the situations of not adding Cu, Ni, Cr, Mo, therefore are the examples that fatigue strength does not have raising.So as can be known, for when reducing the quantity of slag and fatigue strength is improved, preferably the total with Cu, Ni, Cr, Mo is designed to more than 2%.Test number 22 has been to use the result who compares under the situation that welding wire is W19.In this case, C in weld metal amount is high, so the result is that phase transition temperature reduces, and fatigue strength can fully be met, still, as described above, about slag generate and the summer than impact absorb can, as can be known not as the welding wire in the scope of the present invention.

Table 3

Test number	Armor plate strength (MPa)		Thickness of slab (mm)		The welding wire code name	The quantity of slag (g)	Protective gas	Fatigue limit (MPa)	Remarks
	Armor plate strength (MPa)		Thickness of slab (mm)							Steel plate 1	Steel plate 2	Steel plate 1	Steel plate 2
	1	270	270	1.2						Steel plate 1	Steel plate 2	Steel plate 1	Steel plate 2	1.2	W11	0.08	Ar+20％CO ₂	260	Example of the present invention
2	1	270	270	1.2	470	270	1.2	1.2	W12	0.06	Ar+20％CO ₂	360	Example of the present invention	1.2	W11	0.08	Ar+20％CO ₂	260	Example of the present invention
2	3	470	470	0.6	470	270	1.2	1.2	W12	0.06	Ar+20％CO ₂	360	Example of the present invention	0.6	W12	0.07	100％CO ₂	250	Example of the present invention
4	3	470	470	0.6	470	470	0.6	0.8	W12	0.06	Ar+20％CO ₂	260	Example of the present invention	0.6	W12	0.07	100％CO ₂	250	Example of the present invention
4	5	470	470	1.2	470	470	0.6	0.8	W12	0.06	Ar+20％CO ₂	260	Example of the present invention	2.0	W11	0.09	100％CO ₂	380	Example of the present invention
6	5	470	470	1.2	470	270	1.2	2.0	W14	0.05	Ar+20％CO ₂	360	Example of the present invention	2.0	W11	0.09	100％CO ₂	380	Example of the present invention
6	7	470	470	2.0	470	270	1.2	2.0	W14	0.05	Ar+20％CO ₂	360	Example of the present invention	2.0	W15	0.08	Ar+20％CO ₂	420	Example of the present invention
8	7	470	470	2.0	470	470	2.0	2.0	W17	0.35	Ar+20％CO ₂	280	Comparative example (component of weld wire)	2.0	W15	0.08	Ar+20％CO ₂	420	Example of the present invention
8	9	470	470	3.2	470	470	2.0	2.0	W17	0.35	Ar+20％CO ₂	280	Comparative example (component of weld wire)	3.2	W13	0.045	Ar+20％CO ₂	340	Example of the present invention
10	9	470	470	3.2	470	470	3.2	3.2	W14	0.07	Ar+20％CO ₂	380	Example of the present invention	3.2	W13	0.045	Ar+20％CO ₂	340	Example of the present invention
10	11	470	470	3.2	470	470	3.2	3.2	W14	0.07	Ar+20％CO ₂	380	Example of the present invention	3.2	W16	0.40	Ar+20％CO ₂	260	Comparative example (component of weld wire)
12	11	470	470	3.2	470	380	3.2	4.5	W12	0.07	Ar+20％CO ₂	360	Example of the present invention	3.2	W16	0.40	Ar+20％CO ₂	260	Comparative example (component of weld wire)
12	13	470	470	4.5	470	380	3.2	4.5	W12	0.07	Ar+20％CO ₂	360	Example of the present invention	4.5	W15	0.06	Ar+20％CO ₂	400	Example of the present invention
14	13	470	470	4.5	780	570	1.2	2.0	W16	0.07	Ar+20％CO ₂	440	Example of the present invention	4.5	W15	0.06	Ar+20％CO ₂	400	Example of the present invention
14	15	780	570	1.2	780	570	1.2	2.0	W16	0.07	Ar+20％CO ₂	440	Example of the present invention	2.0	W17	0.32	Ar+20％CO ₂	270	Comparative example (component of weld wire)
16	15	780	570	1.2	780	780	2.3	2.3	W11	0.08	Ar+20％CO ₂	380	Example of the present invention	2.0	W17	0.32	Ar+20％CO ₂	270	Comparative example (component of weld wire)
16	17	780	780	2.3	780	780	2.3	2.3	W11	0.08	Ar+20％CO ₂	380	Example of the present invention	2.3	W12	0.06	Ar+20％CO ₂	400	Example of the present invention
18	17	780	780	2.3	780	780	2.3	2.3	W15	0.07	Ar+20％CO ₂	460	Example of the present invention	2.3	W12	0.06	Ar+20％CO ₂	400	Example of the present invention
18	19	780	780	2.3	780	780	2.3	2.3	W15	0.07	Ar+20％CO ₂	460	Example of the present invention	2.3	W16	0.45	Ar+20％CO ₂	260	Comparative example (component of weld wire)
20	19	780	780	2.3	780	780	3.2	4.5	W15	0.08	100％CO ₂	420	Example of the present invention	2.3	W16	0.45	Ar+20％CO ₂	260	Comparative example (component of weld wire)
20	21	780	780	3.2	780	780	3.2	4.5	W15	0.08	100％CO ₂	420	Example of the present invention	4.5	W18	0.05	Ar+20％CO ₂	280	Example of the present invention
22	21	780	780	3.2	470	470	3.2	3.2	W19	0.35	Ar+20％CO ₂	390	Comparative example (component of weld wire)	4.5	W18	0.05	Ar+20％CO ₂	280	Example of the present invention
22	23	470	470	1.2	470	470	3.2	3.2	W19	0.35	Ar+20％CO ₂	390	Comparative example (component of weld wire)	2.0	W20	0.06	100％CO ₂	260	Example of the present invention

As previously discussed,, the slag growing amount of metallic flux cored wire the level identical with solid core welding wire might be controlled at, the coating of the welding point that has used metallic flux cored wire and made might be significantly improved according to the present invention.

Embodiment 2

The one-tenth score value of table 4 expression metallic flux cored wire.Table 4 has provided the quality % and the pack completeness of the composition that adds in the welding wire.Each composition is the quality % all with respect to welding wire.

Table 4

The welding wire code name	The slag agent					Arc stabilizer	Graphite	SiC	C ¹⁾	Si ²⁾	Mn	P	S	Cu、Ni、Cr、Mo					Nb、V、Ti				B	Pack completeness	Summer ratio ³⁾	Remarks
	The slag agent													Cu、Ni、Cr、Mo					Nb、V、Ti								SiO ₂	Na ₂O	Al ₂O ₃	K ₂O	Add up to	Cu	Ni	Cr	Mo	Add up to	Nb	V	Ti	Add up to
	100	0.20	0	0	0.10									0.30	0	0	0.65	0.12	0.75	2.5	0.01	0.007					SiO ₂	Na ₂O	Al ₂O ₃	K ₂O	Add up to	Cu	Ni	Cr	Mo	Add up to	Nb	V	Ti	Add up to	0	0	0	0	0	0	0	0	0	0	10	14	Example of the present invention
101	100	0.20	0	0	0.10	0.20	0	0	0.10	0.30	0	0	0.80	0.30	0	0	0.65	0.12	0.75	2.5	0.01	0.007	0.12	0.75	2.5	0.01	0.007	0.2	0.5	0.2	0	0.9	0	0	0	0	0	8	13	Example of the present invention	0	0	0	0	0	0	0	0	0	0	10	14	Example of the present invention
101	102	0.10	0.05	0.05	0.05	0.20	0	0	0.10	0.30	0	0	0.80	0.30	0	0.20	1.0	0.02	0.35	2.5	0.01	0.007	0.12	0.75	2.5	0.01	0.007	0.2	0.5	0.2	0	0.9	0	0	0	0	0	8	13	Example of the present invention	0	0	0	0	0	0	0	0	0	0	10	11	Example of the present invention
103	102	0.10	0.05	0.05	0.05	0.10	0.05	0	0.05	0.30	0.10	0.05	0.70	0.30	0	0.20	1.0	0.02	0.35	2.5	0.01	0.007	0.08	0.50	2.0	0.01	0.011	0.2	2.5	1.0	0	3.7	0	0	0	0	0	11	16	Example of the present invention	0	0	0	0	0	0	0	0	0	0	10	11	Example of the present invention
103	104	0.10	0.05	0	0.05	0.10	0.05	0	0.05	0.30	0.10	0.05	0.70	0.30	0.10	0.25	0.90	0.08	0.50	2.0	0.01	0.006	0.08	0.50	2.0	0.01	0.011	0.2	2.5	1.0	0	3.7	0	0	0	0	0	11	16	Example of the present invention	0.2	0.5	0.3	0.2	1.2	0	0.05	0	0.05	0.01	11	17	Example of the present invention
105	104	0.10	0.05	0	0.05	0.10	0.05	0.05	0.05	0.25	0	0	0.85	0.30	0.10	0.25	0.90	0.08	0.50	2.0	0.01	0.006	0.12	0.5	2.5	0.01	0.007	0	0	0	0	0	0.01	0.05	0.01	0.07	0.0015	12	17	Example of the present invention	0.2	0.5	0.3	0.2	1.2	0	0.05	0	0.05	0.01	11	17	Example of the present invention
105	150	0.20	0.10	0.30	0.10	0.10	0.05	0.05	0.05	0.25	0	0	0.85	0.70	0	0	1.0	0.12	0.5	2.5	0.01	0.010	0.12	0.5	2.5	0.01	0.007	0	0	0	0	0	0.01	0.05	0.01	0.07	0.0015	12	17	Example of the present invention	0.3	4.5	1.0	0.2	6.0	0	0	0	0	0	14	15	Comparative example (the slag agent is excessive)
151	150	0.20	0.10	0.30	0.10	0.30	0.20	0.10	0.25	0.85	0.10	0	0	0.70	0	0	1.0	0.12	0.5	2.5	0.01	0.010	0.06	0.3	1.5	0.01	0.012	0	0	0	0	0	0	0	0	0	0	12	30	Comparative example (the slag agent is excessive, SiC is very few)	0.3	4.5	1.0	0.2	6.0	0	0	0	0	0	14	15	Comparative example (the slag agent is excessive)
151	152	0	0.10	0.05	0.10	0.30	0.20	0.10	0.25	0.85	0.10	0	0	0.25	0.07	0	1.60	0.16	0.3	2.5	0.012	0.011	0.06	0.3	1.5	0.01	0.012	0	0	0	0	0	0	0	0	0	0	12	30		0	0	0	0	0	0	0	0	0	0	12	- ⁴⁾	Comparative example (SiC is excessive)
201	152	0	0.10	0.05	0.10	0	0	0	0.20	0.20	0	0.15	0.45	0.25	0.07	0	1.60	0.16	0.3	2.5	0.012	0.011	0.04	0.8	2.0	0.01	0.008	0.2	2.5	1.0	0	3.7	0	0	0	0	0	14	21	Example of the present invention	0	0	0	0	0	0	0	0	0	0	12	- ⁴⁾	Comparative example (SiC is excessive)
201	203	0.20	0.05	0	0	0	0	0	0.20	0.20	0	0.15	0.45	0.25	0.10	0.10	0.50	0.12	0.3	2.5	0.01	0.010	0.04	0.8	2.0	0.01	0.008	0.2	2.5	1.0	0	3.7	0	0	0	0	0	14	21	Example of the present invention	0	1.5	0.5	0	2.0	0.01	0.05	0	0.06	0	12	24	Example of the present invention
250	203	0.20	0.05	0	0	0.20	0.30	0.10	0.10	0.70	0.10	0	0.50	0.25	0.10	0.10	0.50	0.12	0.3	2.5	0.01	0.010	0.08	0.3	1.8	0.01	0.009	0.2	1.5	0.5	1.5	3.7	0	0	0	0	0	12	20	Comparative example (SiC is very few)	0	1.5	0.5	0	2.0	0.01	0.05	0	0.06	0	12	24	Example of the present invention
250	251	0.20	0.05	0	0	0.20	0.30	0.10	0.10	0.70	0.10	0	0.50	0.25	0	0	0.3	0.05	0.3	1.5	0.01	0.013	0.08	0.3	1.8	0.01	0.009	0.2	1.5	0.5	1.5	3.7	0	0	0	0	0	12	20	Comparative example (SiC is very few)	0.3	0	0	0.4	0.7	0	0.05	0.05	0.10	0.0008	12	19	Comparative example (the slag agent is excessive, Cu～Ni is very few)

1) C beyond the expression SiC.2) represent beyond the SiC and SiO ₂Si in addition.

3) thickness of slab is the 2V type breach Charpy-type test result of 2.5mm.Gap position is in the weld metal centre.

4) because taking place, crackle do not obtain data.

The welding wire code name is the example of 100 series in the table 4, is the welding wire and the comparative example thereof of the example of the present invention of corresponding SiC composition of the present invention system.

And, in the welding wire of 100 series, are comparison welding wires with respect to SiC composition series solder wire of the present invention since No. 150 welding wires.

In addition, the welding wire code name is that the welding wire of 200 series is welding wire and the comparative examples thereof that added the example of the present invention of a spot of SiC in the welding wire that contains graphite of the present invention.

And, in the welding wire of 200 series, are comparison welding wires with respect to the welding wire of the present invention that in containing the welding wire of graphite, has added a spot of SiC since No. 250 welding wires.

C in the table represents the C beyond the SiC, and the Si in the table represents beyond the SiC and SiO ₂Si in addition.

At first, after the welding wire shown in the use table 4 is made welding point, cut test piece, implement Charpy-type test from the weld metal zone.The objective of the invention is to: improve coating and improve joint fatigue strength by the slag growing amount that reduces the weld metal zone, but because joint toughness is the fundamental characteristics of welding point, therefore in advance by means of the Charpy-type test of welding point, confirm the toughness of weld metal zone of 2 systems of SiC composition series solder wire of the present invention.

Implement the making and the Charpy-type test of welding point by following order.

At first, prepare thickness of slab and be 2 pieces of the 780MPa grade steel plates of 3.2mm, thereby after implementing butt welding and make welding point with I type groove between the end of these 2 pieces of steel plates, make 2mV type breach, make obtaining the thick summer for 2.5mm than impacting test piece by the centre that is machined in weld metal.

Test piece cut position such as schematic diagram as shown in Figure 6, the position that will comprise I groove and butt welding W cuts position S as the summer than what impact test piece.

Use this test piece, implement Charpy-type test down, measure it and absorb energy at 0 ℃.Charpy-type test the results are shown in table 4.About the welding wire in the table 4 152,, therefore can not carry out Charpy-type test owing in the welding point solidification cracking has taken place.

The summer of the welding point that the SiC composition series solder wire by in the composition compositing range of the present invention's regulation shown in the table 4 is made absorbs energy than impacting, and is toughness joint level without a doubt in the practicality.And, welding wire code name in the table 4 is the welding wire of 151 comparative example, although absorb can be high than impacting than summer of the welding wire of the present invention example, as described later, depart from scope of the present invention owing to be used to reduce the composition of phase transition temperature, therefore do not improve the effect of joint fatigue strength.

Secondly, measure the slag generating capacity and the joint fatigue strength of weld metal zone.

At first, implement the assay method of slag generating capacity like that according to the following stated.

About the slag generating capacity, after the fatigue specimen of narration cuts the welding point of usefulness below making, measure the weight of this joint.Then remove welding slag, once more gravimetry attached to the surface.Then, calculate this weight difference, as the slag generating capacity of this joint.In addition, fatigue specimen cuts the 250mm that is made into certain-length with the welding bead length of welding point all the time, therefore comes each welding wire of comparison by comparing its slag generating capacity.Cut fatigue specimen from joint then.

Secondly, use the test piece that cuts from welding point, implement fatigue test in the following order, measure joint fatigue strength.

Prepare 2 pieces of steel plates, implement lap fillet welding, after having investigated the slag generating capacity, cut the fatigue specimen shown in Fig. 5 (a), Fig. 5 (b) from this joint.Then, the direction of arrow of Fig. 5 (b) is applied fatigue loading as fatigue load additional directions P, the range of stress that fatigue crack will not take place through loading repeatedly for 2,000,000 times is defined as the fatigue strength of this joint, and this value is compared.Stress ratio R is R=0.1.Steel plate 1 and steel plate 2 not necessarily use same steel plate, also can select 3 and 4 combination of varying strength and thickness of slab.And the value that is applied to the stress of test piece detects by paste foil gauge near the welding bead of the upper surface of steel plate 1.

At first, code name is that the welding wire of 100 series is made welding point under the conditions shown in Table 5 in the welding wire of use table 4, measures the slag generating capacity and the joint fatigue strength of weld metal zone then, and it the results are shown in table 5.

The component of weld wire of test number A1 within the scope of the invention, therefore, the slag generating capacity is 0.07g, not enough 0.1g is to have reached the example that reduces slag.And, in order to reach high-fatigue strength, as test number A2, improve armor plate strength and get final product.

The component of weld wire of test number A3, A10 also within the scope of the invention, the not enough 0.1g of slag generating capacity is to reach the example that reduces slag.And in order also to reach high-fatigue strength, as test number A4 or A2, the thickness of adjusting steel plate gets final product.

The armor plate strength of the comparative example of test number A11 and steel plate thickness are all within the scope of the present invention, the content of SiC within the scope of the invention in the component of weld wire, therefore can reach the raising of fatigue strength, but the total content of slag agent in the component of weld wire is higher than scope of the present invention, therefore can not reduce the quantity of slag.

SiC content in the component of weld wire of the comparative example of test number A12, A13, the total content of slag agent are all outside scope of the present invention, so the reduction of the raising of fatigue strength and slag generating capacity does not all reach.

And crackle takes place in the welding wire that the welding wire shown in the table 4 is numbered 152 comparative example when implementing Charpy-type test, therefore fail to implement fatigue test.

On the other hand, the example of test number A2, A4～A9, fatigue strength all is higher than 300MPa, and the slag generating capacity has reached not enough 0.1g.

From as can be known above, the A1～A10 in the table 5 of example of the present invention, the slag generating capacity has all reached not enough 0.1g, and in contrast to this, the slag generating capacity of the A11～A13 of comparative example is more than the 0.5g, can reach the reduction of the quantity of slag as can be known by utilization the present invention.And, if adjust armor plate strength and steel plate thickness, as test number A2, A4～A9, fatigue strength is become more than the 300MPa.

Table 5

Test number	Armor plate strength (MPa)		Thickness of slab (mm)		The welding wire code name	The quantity of slag (g)	Protective gas	Fatigue limit (MPa)	Remarks
	Armor plate strength (MPa)		Thickness of slab (mm)							Steel plate 1	Steel plate 2	Steel plate 1	Steel plate 2
	A1	270	270	1.2						Steel plate 1	Steel plate 2	Steel plate 1	Steel plate 2	1.2	100	0.07	Ar+20％CO ₂ +2％O ₂	200	Example of the present invention
A2	A1	270	270	1.2	470	470	1.2	1.2	100	0.06	Ar+20％CO ₂	330	Example of the present invention	1.2	100	0.07	Ar+20％CO ₂ +2％O ₂	200	Example of the present invention
A2	A3	470	470	0.6	470	470	1.2	1.2	100	0.06	Ar+20％CO ₂	330	Example of the present invention	0.6	101	0.08	100％CO ₂	220	Example of the present invention
A4	A3	470	470	0.6	470	470	3.2	3.2	101	0.06	Ar+20％CO ₂	350	Example of the present invention	0.6	101	0.08	100％CO ₂	220	Example of the present invention
A4	A5	470	570	1.2	470	470	3.2	3.2	101	0.06	Ar+20％CO ₂	350	Example of the present invention	2.0	102	0.08	100％CO ₂	360	Example of the present invention
A6	A5	470	570	1.2	470	470	2.0	2.0	103	0.05	Ar+20％CO ₂	340	Example of the present invention	2.0	102	0.08	100％CO ₂	360	Example of the present invention
A6	A7	470	470	2.0	470	470	2.0	2.0	103	0.05	Ar+20％CO ₂	340	Example of the present invention	2.0	104	0.06	Ar+20％CO ₂	320	Example of the present invention
A8	A7	470	470	2.0	570	780	2.0	2.0	104	0.06	Ar+20％CO ₂	340	Example of the present invention	2.0	104	0.06	Ar+20％CO ₂	320	Example of the present invention
A8	A9	780	780	4.2	570	780	2.0	2.0	104	0.06	Ar+20％CO ₂	340	Example of the present invention	4.2	105	0.07	Ar+20％CO ₂ +3％O ₂	340	Example of the present invention
A10	A9	780	780	4.2	780	780	7.0	7.0	100	0.05	Ar+20％CO ₂	230	Example of the present invention	4.2	105	0.07	Ar+20％CO ₂ +3％O ₂	340	Example of the present invention
A10	A11	470	470	3.2	780	780	7.0	7.0	100	0.05	Ar+20％CO ₂	230	Example of the present invention	3.2	150	0.50	Ar+20％CO ₂	340	Comparative example (component of weld wire)
A12	A11	470	470	3.2	470	470	3.2	3.2	151	0.60	Ar+20％CO ₂	220	Comparative example (component of weld wire)	3.2	150	0.50	Ar+20％CO ₂	340	Comparative example (component of weld wire)
A12	A13	470	470	4.5	470	470	3.2	3.2	151	0.60	Ar+20％CO ₂	220	Comparative example (component of weld wire)	4.5	151	0.61	Ar+20％CO ₂	210	Comparative example (component of weld wire)

Secondly, the welding wire of 200 series in the welding wire of use table 4 is made welding point under the conditions shown in Table 6, measures the slag generating capacity and the joint fatigue strength of weld metal zone then, and it the results are shown in table 6.

The slag generating capacity of table 6 and fatigue strength are the embodiment that has added in the welding wire that contains graphite of the present invention under the situation of a spot of SiC.The investigation order of fatigue strength investigation method and slag generating capacity is identical with above-mentioned explanation.

Test number be B3 component of weld wire within the scope of the invention, the quantity of slag is 0.09g, reached not enough 0.1g, promptly is to have reached the example that reduces the quantity of slag.But, because steel plate thinner thickness, the phase change expansion that can not fully restrain weld metal, so not raising of fatigue strength.With respect to test number B3, improve in order to make fatigue strength, can as test number B4, adjust steel plate thickness.

Test number be B9 component of weld wire within the scope of the invention, the quantity of slag is 0.05g, has reached not enough 0.1g, promptly is to reach the example that reduces the quantity of slag.But because the back side that steel plate thickness is thicker, sweating heat can not fully arrive steel plate, after the phase transformation of weld metal finished, stress transferred the tensile stress state once more to, and fatigue strength does not improve.With respect to test number B9, improve in order to make fatigue strength, can as test number B8, adjust steel plate thickness.

And, test number be the armor plate strength of comparative example of B10 and steel plate thickness all within the scope of the invention, the total content of SiC content in the component of weld wire and Cu, Ni, Cr, Mo within the scope of the invention, therefore can reach fatigue strength, but the total content of slag agent in the component of weld wire is higher than scope of the present invention, so the reduction of the quantity of slag fails to reach.

Test number is that Cu, the Ni in the component of weld wire of comparative example of B11, the total content of Cr, Mo are lower than scope of the present invention, so the reduction of the starting temperature of transformation of weld metal is insufficient, and fatigue strength does not improve.

Test number B4～B8 is within the scope of the invention examples of the intensity of component of weld wire and steel plate and thickness of slab.The equal not enough 0.1g of the slag generating capacity of these examples can reach the reduction of the quantity of slag, and is that fatigue strength is all above the example that can reach the high-fatigue strength joint of 300MPa.

From above result as can be known, in order to realize reducing the quantity of slag, must be within the scope of the invention with the component of weld wire restriction; In order further to reach high-fatigue strength, armor plate strength and thickness of slab must be limited within the scope of the invention.

Table 6

Test number	Armor plate strength (MPa)		Thickness of slab (mm)		The welding wire code name	The quantity of slag (g)	Protective gas	Fatigue limit (MPa)	Remarks
	Armor plate strength (MPa)		Thickness of slab (mm)							Steel plate 1	Steel plate 2	Steel plate 1	Steel plate 2
	B3	470	470	0.6						Steel plate 1	Steel plate 2	Steel plate 1	Steel plate 2	0.6	201	0.09	100％CO ₂	220	Example of the present invention
B4	B3	470	470	0.6	470	470	3.2	3.2	201	0.06	Ar+20％CO ₂	350	Example of the present invention	0.6	201	0.09	100％CO ₂	220	Example of the present invention
B4	B6	470	470	2.0	470	470	3.2	3.2	201	0.06	Ar+20％CO ₂	350	Example of the present invention	2.0	201	0.05	Ar+20％CO ₂	340	Example of the present invention
B8	B6	470	470	2.0	780	780	4.2	4.2	203	0.06	Ar+20％CO ₂	340	Example of the present invention	2.0	201	0.05	Ar+20％CO ₂	340	Example of the present invention
B8	B9	780	780	7.0	780	780	4.2	4.2	203	0.06	Ar+20％CO ₂	340	Example of the present invention	7.0	203	0.05	Ar+20％CO ₂	230	Example of the present invention
B10	B9	780	780	7.0	470	470	3.2	3.2	250	0.40	Ar+20％CO ₂	340	Comparative example (component of weld wire)	7.0	203	0.05	Ar+20％CO ₂	230	Example of the present invention
B10	B11	470	470	3.2	470	470	3.2	3.2	250	0.40	Ar+20％CO ₂	340	Comparative example (component of weld wire)	3.2	251	0.05	Ar+20％CO ₂	220	Comparative example (component of weld wire)

According to the present invention, the quantity of slag that takes place in the time of the use metallic flux cored wire might being carried out arc welding is suppressed at and the same low level of solid core welding wire.Because the slag generating capacity is few, therefore the welding point of making carries out coating without the slagging-off operation, can former state keeps using the efficient of the existing automobile making operation of solid core welding wire.

And, by limiting the composition in the welding wire, the fatigue strength of welding point is especially improved, therefore, welding point preparation method provided by the invention can be at the welding point that keeps making under the high efficiency state of automobile making high-fatigue strength.

Claims

1. metallic flux cored wire; it is characterized in that: the gas shielded arc welding metallic flux cored wire that forms for intracutaneous filling solder flux outside steel; in all quality % of welding wire, contain beyond the graphite and SiC beyond C:0.001～0.20%, graphite: 0.10～0.7%, beyond the SiC and SiO ₂Si:0.05 in addition～1.2%, Mn:0.2～3.0%, restriction P:0.03% is following, S:0.02% is following and contain SiO ₂, Al ₂O ₃, Na ₂O and K ₂O more than a kind or 2 kinds and add up to 0.05～0.40% and surplus form by iron and unavoidable impurities; And, contain described graphite and described SiO as described solder flux at least ₂, Al ₂O ₃, Na ₂O and K ₂More than a kind or 2 kinds of O.

2. metallic flux cored wire according to claim 1 is characterized in that: in described metallic flux cored wire, in all quality % of welding wire, also contain SiC:0.05～0.6%.

3. metallic flux cored wire according to claim 1 and 2 is characterized in that: in described metallic flux cored wire, the solder flux pack completeness is 10～20%.

4. according to any one described metallic flux cored wire of claim 1～3, it is characterized in that: for described metallic flux cored wire, in all quality % of welding wire, also contain Ni:0.5～12.0%, Cr:0.1～3.0%, Mo:0.1～3.0%, Cu:0.1～0.5% more than a kind or 2 kinds and add up to 0.2～12.5%.

5. according to any one described metallic flux cored wire of claim 1～4, it is characterized in that:,, also contain B:0.001～0.03% in all quality % of welding wire for described metallic flux cored wire.

6. according to any one described metallic flux cored wire of claim 1～5, it is characterized in that: for described metallic flux cored wire, in all quality % of welding wire, also contain Nb, V, Ti more than a kind or 2 kinds and add up to 0.005～0.3%.

7. according to any one described metallic flux cored wire of claim 1～6, it is characterized in that:,,, also contain 0.05～0.5% oxide based arc stabilizer in addition in all quality % as described solder flux for described metallic flux cored wire.

8. metallic flux cored wire; the gas shielded arc welding metallic flux cored wire that forms for intracutaneous filling solder flux outside steel; in all quality % of welding wire, contain beyond the graphite and SiC beyond C:0.01～0.20%, SiC:0.6～1.2%, SiC beyond and SiO ₂Si:0.05 in addition～1.2%, Mn:0.2～3.0%, restriction P:0.03% is following, S:0.02% is following and contain SiO ₂, Al ₂O ₃, Na ₂O and K ₂O more than a kind or 2 kinds and add up to 0.05～0.40% and surplus form by iron and unavoidable impurities; And intracutaneous outside steel contains described SiC and described SiO as solder flux at least ₂, Al ₂O ₃, Na ₂O and K ₂More than a kind or 2 kinds of O.

9. metallic flux cored wire according to claim 8 is characterized in that: in described metallic flux cored wire, and intracutaneous outside steel, at least as described solder flux, the quality % all in welding wire also contains graphite: 0.05～0.4%.

10. according to Claim 8 or 9 described metallic flux cored wires, in described metallic flux cored wire, in all quality % of welding wire, also contain Ni:0.5～5.0%, Cr:0.1～2.0%, Mo:0.1～2.0%, Cu:0.1～0.5% more than a kind or 2 kinds and add up to 0.5～6.0%.

11. the described metallic flux cored wire of according to Claim 8～10 any one is characterized in that: in described metallic flux cored wire, the quality % all in welding wire also contains B:0.001～0.015%.

12. the described metallic flux cored wire of according to Claim 8～11 any one, it is characterized in that: in described metallic flux cored wire, in all quality % of welding wire, also contain Nb, V and Ti more than a kind or 2 kinds and add up to 0.005～0.3%.

13. the described metallic flux cored wire of according to Claim 8～12 any one, it is characterized in that: in described metallic flux cored wire, intracutaneous outside steel, at least as described solder flux, in all quality % of welding wire also contain 0.05～0.5% oxide based beyond arc stabilizer.

14. a gas-shielded arc welding method is characterized in that: use any one described metallic flux cored wire to come welding steel according to claim 1～13.

15. gas-shielded arc welding method according to claim 14 is characterized in that:, use and contain 3～25% CO as protective gas ₂, and the protective gas that constitutes by Ar gas and unavoidable impurities of surplus.

16., it is characterized in that: use and in described protective gas, also contain 4% following O according to claim 14 or 15 described gas-shielded arc welding methods ₂The protective gas of gas.

17. any one the described gas-shielded arc welding method according to claim 14～17 is characterized in that: the thickness of slab of described steel plate is that 1.0～5.0mm and tensile strength are 440～980MPa.

18. the preparation method of the high-fatigue strength welding point that the quantity of slag is few is characterized in that: use any one described gas-shielded arc welding method of claim 14～17 to come welding steel.