CN1318181C

CN1318181C - Submerged-arc welding point, producing method of the same welding point, and used solder wire and flux

Info

Publication number: CN1318181C
Application number: CNB2004100978059A
Authority: CN
Inventors: 矢埜浩史; 早川直哉; 安田功一
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 2000-10-06
Filing date: 2001-09-30
Publication date: 2007-05-30
Anticipated expiration: 2021-09-30
Also published as: KR20020027238A; CN1347781A; CN1616183A; CN1318180C; CN1616184A; TW574380B; KR100508399B1; CN1200791C

Abstract

To provide a steel wire for large heat input submerged arc welding which makes it possible to obtain weld metal having excellent toughness and a method of manufacturing a welded joint as well as the welded joint. The steel wire containing 0.03 to 0.10% C, <=0.0035% N, <=0.40% Si, 1.0 to 2.5% Mn and >=0.003% Ti and satisfying Ti/N: 15 to 50 is used as the welding wire in welding steel products having a base metal composition of <=0.006 mass% Ti and <=0.012% Nb by large heat input submerged arc welding of heat input >=159 kJ/cm. The steel wire may further contain one or >=2 kinds among Mo, Nb, B and Ni. A flux containing boron oxide or further <=0.0030 mass% N of iron powder is preferably used. As a result, the weld metal has a structure of <=15 area% in grain boundary ferrite quantity and has high toughness.

Description

The manufacture method of used for submerged arc welding solder flux and submerged-arc welding welding point

The application is to be September 30 calendar year 2001, application number the dividing an application for the application for a patent for invention of " method for making of large-line energy submerged arc welding joint, this joint and used welding wire and solder flux " that be 01135349.X, denomination of invention the applying date.

Technical field

The present invention relates to the large-line energy submerged arc welding, particularly relate to the welding point that is suitable for the large-line energy submerged arc welding of heat input more than 150kJ/cm, manufacture method and the employed welding wire and the solder flux of this joint.

Background technology

In welding procedure, always do one's utmost to wish to improve welding efficiency.In order to improve welding efficiency generally is to improve weld heat input.But common one improves the then toughness decline of weld metal of weld heat input.Its reason is to follow the increase of weld heat input, and the cooling velocity of weld zone reduces, the easy alligatoring of the tissue of weld metal.

Thereby submerged arc welding method is the method that electric arc carries out continuous welding that produces in the solder flux in interspersing among bevel for welding.Even big electric current also can form stable electric arc, widely utilize in the field of joint steel plates such as shipbuilding, bridge, pressure vessel, industrial machine as the high efficiency welding method that can obtain dark fusion penetration and big deposited amount.But, so submerged arc welding method has the weld heat input height owing to adopt big electric current to weld, the tendency that the toughness of weld metal reduces easily.

At this problem, for example opening disclosed technology on the flat 7-328793 communique the spy is to add the oxide of boron (B) during in submerged arc welding in solder flux, makes weld metal contain the toughness that B improves weld metal by solder flux.The technology that Te Kaiping 7-328793 communique is put down in writing is to contain B by the composition that makes submerged arc welding flux ₂O ₃: the Si content of 0.7～2.0 quality %, reduction welding wire, with the Mn content optimization in solder flux and the welding wire, improve the welding method of the toughness of weld metal.

But problem is, open the technology that flat 7-328793 communique is put down in writing according to the spy, the toughness that adopts the resulting weld metal of large-line energy submerged arc welding is because the different situations that remarkable deterioration is arranged of steel that use and/or welding wire, can not obtain stablizing and the weld metal of the large-line energy of high tenacity.

Summary of the invention

The objective of the invention is to solve the problem that above-mentioned prior art exists, provide, particularly, when the large-line energy submerged-arc welding welding steel that adopt heat input more than 150kJ/cm, also can obtain having large-line energy submerged-arc welding welding point, the manufacture method of this joint and the welding wire and the solder flux that for this reason uses of the weld metal of excellent in toughness.

That is to say, the present invention is a kind of submerged-arc welding welding point and manufacture method thereof, it is characterized in that: in the manufacture method of the submerged-arc welding welding point by the large-line energy submerged-arc welding solder joints of weld heat input more than 150kJ/cm and this joint, the weld metal composition of above-mentioned welding point is represented with quality %, contain C:0.03～0.15%, Si:0.10～1.00%, Mn:0.70～2.50%, Ti:0.003～0.030%, below the N:0.0050%, and the grain boundary ferrite growing amount in the above-mentioned weld metal is below the 15.0 area %.

Again, the ideal situation that the present invention wishes is that above-mentioned weld metal is represented with quality %, also contain from Mo:0.10～0.50%, Nb:0.010～0.20%, Ni:0.05%～1.00%, select more than a kind or 2 kinds, and satisfy 0.60≤B/N≤1.20, and the grain boundary ferrite growing amount in the above-mentioned weld metal is below the 10.0 area %.

Again, the present invention is a kind of large-line energy welding wire for hidden arc welding, this welding wire is that the submerged arc welding that is used for the low heat input of weld heat input below 150kJ/cm is certain, and be the welding wire that is used for the large-line energy submerged arc welding of weld heat input more than 150kJ/cm, it is characterized in that, % represents with quality, this welding wire has the C:0.03 of containing～0.10%, below the N:0.0035%, below the Si:0.40%, Mn:1.00～2.50%, also contain Ti more than 0.030% and satisfy Ti/N:15～50, remainder is by forming that Fe and unavoidable impurities constitute.

Again, the present invention forms on the basis at above-mentioned welding wire, % represents with quality, ideal situation be also contain from Mo:0.10～0.60%, Nb:0.010～0.100%, B:0.0005～0.0100%, Ni:0.20%～2.00%, select more than a kind or 2 kinds.

Again, the present invention is the manufacture method with submerged-arc welding welding point of good weld metal zone toughness, it is characterized in that: in the manufacture method of the submerged-arc welding welding point by the large-line energy submerged-arc welding solder joints of weld heat input more than 150kJ/cm, employing represents to have the C:0.03 of containing with quality %～0.10%, below the N:0.0035%, below the Si:0.40%, Mn:1.00～2.50%, also contain Ti more than 0.030% and satisfy Ti/N:15～50, perhaps also contain from Mo:0.10～0.60%, Nb:0.010～0.100%, B:0.0005～0.0100%, select in Ni:0.20%～2.00% more than a kind or 2 kinds, the large-line energy welding wire for hidden arc welding of forming that remainder is made of Fe and unavoidable impurities will have Ti content below 0.006 quality %, the steel that the mother metal of Nb content below 0.012 quality % formed weld.

Again, the present invention is on the above-mentioned welding wire basis that is used for above-mentioned large-line energy submerged arc welding, oxide with boracic in the solder flux, perhaps also contain the following iron powder of 8 quality % alloyed powder in addition, perhaps represent, also contain the N that contains that accounts for solder flux total amount 20～45% and be advisable at the solder flux of the iron powder below 0.0030% with quality %.

Again, the present invention is the used for submerged arc welding solder flux of being put down in writing in (1) or (2), it is certain that this solder flux can be used for the low heat input submerged arc welding of weld heat input below 150kJ/cm, but also be the solder flux that is used for the large-line energy submerged-arc welding of weld heat input more than 150kJ/cm, it is characterized in that, when using generally well-known welding wire, contain the atomized iron powder of N content below 0.0030 quality % that accounts for solder flux total amount 20～45%, also contain the B compound that useful B conversion accounts for solder flux total amount 0.03～0.30 quality %, perhaps also contain from following (A) group and (B) group select more than 1 group or 2 groups, (A) group: with the Mo powder, 0.2～2.0 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Mo conversion total in molybdenum-iron powder and the Mo compound powder; (B) group: with 0.02～0.15 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Nb conversion total in Nb powder, ferro-niobium powder and the Nb compound powder.

Again, the submerged arc flux that the present invention relates to is characterized in that: represent also to contain from SiO with respect to the solder flux total amount with quality % ₂: 10～28%, CaCO ₃: 5～15%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds.

The present invention relates to have the manufacture method of the submerged-arc welding welding point of good weld metal zone toughness again, this method is in the manufacture method of the submerged-arc welding welding point by the large-line energy submerged-arc welding solder joints of weld heat input more than 150kJ/cm, it is characterized in that: the N amount that contains that adopts solder flux to contain in forming to account for solder flux total amount 20～45 quality % the solder flux welding of the atomized iron powder below the 0.0030 quality % have Ti content below the 0.006 quality %, the steel formed of the mother metal of Nb content below 0.012 quality %.

Again, the present invention relates to a kind of manufacture method of submerged-arc welding welding point, it is characterized in that: above-mentioned solder flux is formed and is also contained useful B and convert and account for the B compound of solder flux total amount 0.03～0.30 quality %, also contain from following (A) group and (B) select the group more than 1 group or 2 groups.(A) group: with 0.2～2.0 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Mo conversion total in Mo powder, molybdenum-iron powder and the Mo compound; (B) group: with 0.02～0.15 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Nb conversion total in Nb powder, ferro-niobium powder and the Nb compound.Perhaps, represent also to contain with quality % from SiO with respect to the solder flux total amount ₂: 10～28%, CaCO ₃: 5～15%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds.

Description of drawings

Figure 1A: be the schematic diagram of groove shape overview that expression is used for the welding point of the embodiment of the invention 1.

Figure 1B: be the schematic diagram of groove shape overview that expression is used for the welding point of the embodiment of the invention 1.

Fig. 2 A: be the key diagram that the sample position of the tensile sample that adopts in embodiment 1～3 schematically is described.

Fig. 2 B: be the key diagram that the sample position of the impact specimen that adopts in embodiment 1～3 schematically is described.

Fig. 3: be the schematic diagram of groove shape overview that expression is used for the welding point of the embodiment of the invention 2 and 3.

Fig. 4: grain boundary ferrite growing amount and Xia Bi in the expression weld metal absorb merit (vE ₀) relation.

Fig. 5: the quality % ratio of the B/N in the expression weld metal and the relation of grain boundary ferrite growing amount.

The specific embodiment

The inventor etc. are in order to finish above-mentioned problem, adopt the large-line energy submerged-arc welding of weld heat input more than 150kJ/cm to engage, concentrate on studies about the various factors of the toughness that influences the gained weld metal as 490～520MPa level steel of materials to be welded.Found that the toughness of the weld metal that obtains by the large-line energy submerged-arc welding of weld heat input more than 150kJ/cm is very responsive to nitrogen, sometimes because little by little variation of nitrogen content causes the remarkable deterioration of toughness.

Particularly at Ti and Nb content after a little while, owing to increasing microstructure coarsening that nitrogen content causes weld metal, remarkable deterioration a little as the steel of materials to be welded.This generally thinks because steel contain the Ti amount after a little while, can not fully supply with Ti to weld metal, is difficult to adjust due to the solid solution N content.

The inventor etc. have further launched discussion based on above-mentioned opinion, the result expects: also can obtain stable and the large-line energy submerged-arc welding seam metal of high tenacity in order to contain Ti and Nb amount in the steel as materials to be welded after a little while, when suitably adjusting the N content of welding wire, by making an amount of Ti that contains in the welding wire corresponding to N content in the welding wire, thereby also may obtain fine weld structure even carry out the large-line energy welding.

The inventor etc. have carried out stably giving large-line energy submerged-arc welding seam metal more research, the discussion of high tenacity.Originally, absorb merit, toughness value (vE with regard to grain boundary ferrite growing amount in the weld metal and Xia Bi ₀) relation to adopt weld heat input the welding of the large-line energy submerged-arc welding more than 150kJ/cm Ti content below the 0.006 quality %, the weld metal of the steel gained of the thickness of slab 40mm of Nb content below 0.012 quality % investigates.Its investigation the results are shown in Fig. 4, can get following new opinion by Fig. 4: by making grain boundary ferrite growing amount in the weld metal below 15 area %, ideal situation is below the 10 area %, can stably give high tenacity.

The quality % ratio of the B/N in the weld metal and the relation of grain boundary ferrite growing amount have also been investigated.It the results are shown in Fig. 5.Fig. 5 shows, contain Mo, Nb etc. in the welding wire and add an amount of Mo, Nb etc. in weld metal, B/N quality % ratio is adjusted into desired value by making, the grain boundary ferrite growing amount of weld metal is controlled at that 15.0 area % are following, ideal situation is to be possible below the 10.0 area %.

In addition, the welding wire that the adjustment of the solid solution nitrogen content in the weld metal contains Ti and Nb as welding wire by use can have improvement to a certain degree, but uses when not containing the welding wire of Ti and Nb as welding wire, and it adjusts difficult, the remarkable deterioration of the toughness of weld metal.Use when not containing the welding wire of Ti, the toughness deterioration of weld metal is remarkable especially.

Usually for the widely-used high 490～520MPa level steel of property, Ti content below the 0.006 quality %, Nb content below 0.012 quality % to contain the few steel of Ti, Nb representative, be difficult to obtain stable in the time of most and the weld metal of high tenacity.The urgent welding of wishing to obtain being applicable to this steel, the stable and weld metal of good-toughness.

The inventor etc. are based on above-mentioned opinion, further carried out discussion, the result expects: by the Ti of welding steel material and Nb content after a little while, even use the welding wire that does not particularly contain Ti to carry out the large-line energy submerged arc welding, pass through to use the atomized iron powder of N content below 0.0030 quality % as the iron powder that adds in the solder flux, also may obtain stable and the weld metal of high tenacity.In addition, in order stably to give large-line energy submerged-arc welding seam metal higher toughness, wish to make to contain Mo, Nb etc. in the solder flux, by adding an amount of Mo and Nb etc. to weld metal, the quality % ratio of B/N is adjusted into desired value, the grain boundary ferrite growing amount in the weld metal is controlled at that 15.0 area % are following, ideal situation is to be possible below the 10.0 area %.In this occasion, effect becomes big when adding to a spot of Ti in the weld metal by solder flux.

The one-tenth of the weld metal that the large-line energy submerged-arc welding welding that more than illustrates obtains is grouped in following scope is advisable.Below quality % in composition only represent with %.

C：0.03～0.15％

C amount in the weld metal is as if less than 0.03%, and the toughness of weld metal is difficult to improve, and one surpasses 0.15%, causes weld crack easily.Thereby C content is taken as C:0.03～0.15% in the weld metal.

Si：0.10～1.00％

Si amount in the weld metal is as if less than 0.10%, and the oxygen content of weld metal uprises, and is difficult to obtain good weld metal toughness.In addition, the Si amount one in the weld metal surpasses 1.00%, then generates the island martensite body in weld metal, and the toughness of weld metal is tending towards deterioration.So to measure be 0.10～1.00% to Si in the weld metal.

Mn：0.70～2.50％

Mn amount in the weld metal is as if less than 0.70%, and then the pearlitic transformation in weld metal is suppressed, the toughness deterioration of weld metal.On the other hand, the Mn amount one in the weld metal surpasses 2.50%, then generates the island martensite body in weld metal, and the toughness of weld metal is tending towards deterioration.So to measure be 0.70～2.50% to Mn in the weld metal.

Ti：0.003～0.030％

Ti exists as oxide in weld metal, works as ferritic forming core core, and be that the ferrite refinement is necessary., its Ti content is as if less than 0.003%, and this effect is insufficient.In addition, the Ti amount one in the weld metal surpasses 0.030%, and the intensity of weld metal becomes too high, is easy to generate by the low temperature crackle due to the hardness rising of weld metal.So it is 0.003～0.030% that the Ti in the weld metal is measured.

Below the N:0.0050%

N is the element that makes the toughness deterioration of weld metal, and the present invention wishes to reduce as far as possible.Owing to contain the N amount in the weld metal once surpassing 0.0050% toughness deterioration, so be limited to below 0.0050%.Secondly, it also is possible below 0.0020% that N content is reduced to, but because the welding material cost increases, and the manufacturing expense of welding point uprises, so wish more than 0.0020%.

From Mo:0.10～0.50%, Nb:0.010～0.200%, Ni:0.05%～1.00%, select more than a kind or 2 kinds

Mo, Nb, Ni have the effect that the toughness that makes weld metal significantly improves, and the present invention can select as required, contain.Mo, Nb are suppressed at the generation of the thick grain boundary ferrite that austenite grain boundary separates out, and the toughness of weld metal is improved.This effect more than containing Mo:0.10%, to contain Nb:0.010% remarkable when above.On the other hand, content surpasses Mo:0.50%, Nb:0.200% respectively, and the tissue of weld metal becomes upper bainite easily, the toughness deterioration.Thus, preferable range is respectively Mo:0.10～0.50%, Nb:0.010～0.200%.

In addition, Ni improves the toughness of ferritic phase, and the toughness of weld metal is improved.This effect is 0.05% remarkable when above at content.On the other hand, one surpasses 1.00%, just causes the generation of low temperature crackle easily.Therefore, the Ni preferable range is 0.05%～1.00%.

Grain boundary ferrite growing amount in the weld metal: below the 15.0 area %

In order stably to give large-line energy submerged-arc welding seam metal higher toughness, not only only adjust the composition of weld metal, also be necessary to make grain boundary ferrite growing amount in the weld metal below 15.0 area %.In order more stably to obtain high tenacity, the grain boundary ferrite growing amount in the weld metal is necessary below 10.0 area %.Secondly, observe weld metal and measured grain boundary ferrite growing amount wherein.Use light microscope, electron microscope etc. in the observation, observing multiplying power is 10～500 times.To corrode by corrosive liquid behind the sightingpiston grinding and polishing, and use the image analysis treating apparatus will observe picture and carry out the image processing, obtain the grain boundary ferrite growing amount in the weld metal.The mensuration of grain boundary ferrite growing amount needn't limit especially in the weld metal, and common assay method is also applicable.

0.60≤B/N≤1.20

In order to make grain boundary ferrite growing amount in the weld metal below 10.0 area %, not only adjust the solid solution N amount of weld metal, also need in weld metal, to add an amount of Mo, Nb etc., adjust the quality % ratio of the B/N in the weld metal simultaneously.B is suppressed at the generation of the thick grain boundary ferrite that austenite grain boundary separates out, and is the element that the toughness of weld metal is improved.The quality % ratio of B/N is as if less than 0.60, and its effect is insufficient, can not stably obtain higher toughness.In addition, the quality % of B/N surpasses 1.20 than one, and toughness is with regard to deterioration.So the quality % of the B/N in the weld metal is advisable below 1.20 than with more than 0.60.

As the 1st method of the weld metal that obtains the invention described above, by limiting the method that welding wire is formed.At this moment solder flux does not need special qualification, and generally well-known sintered flux all can use.

At first, the qualification reason of forming about large-line energy submerged-arc welding wire of the present invention is illustrated.Below quality % in composition only represent with %.

C：0.03～0.10％

C is the element that increases weld metal intensity, and the present invention contains more than 0.03% in welding wire in order to ensure desirable weld metal intensity.If C content in the welding wire is difficult to obtain the weld metal intensity of defined less than 0.03%, and the CO dividing potential drop step-down in arc atmosphere during welding, worries to be involved in from atmosphere N, and the N content of weld metal increases.On the other hand, content one surpasses 0.10%, and the C content in the weld metal increases, and in the time of the toughness deterioration of weld metal, heat cracking takes place easily.Therefore, C is limited to C:0.03～0.10%.Have, ideal situation is 0.04～0.08% again.

Below the N:0.0035%

N is the element that makes the toughness deterioration of weld metal, wishes reduction as far as possible and the N too high levels that content one surpasses in 0.0035% weld metal in welding wire in the present invention, the toughness deterioration.Therefore, N is limited to below 0.0035%.Have, it also is possible below 0.0010% that N content is reduced to again, but the increase of concise cost is a high price, so wish that N content is more than 0.0010% economically.

Below the Si:0.40%

Si works as deoxidier, is the element that effectively reduces the oxygen in the weld metal.Contain but one surpasses 0.40% volume, the cementite that then suppresses weld metal generates, and when generating the island martensite body, promotes ferritic alligatoring, makes the toughness deterioration of weld metal.Therefore, Si is limited to below 0.40%.Secondly, the Si of steel or the SiO in the solder flux ₂Also supply Si, the Si in the welding wire is to be advisable below 0.30%.

Mn：1.00～2.50％

Mn works as deoxidier, is the element that effectively reduces the oxygen in the weld metal.Mn improves quenching degree in addition, and thinning microstructure has the effect that the intensity of weld metal is increased by solution strengthening simultaneously.In order to obtain this effect, need to contain the Mn more than 1.00% among the present invention.If contain quantity not sufficient 1.00%, then be difficult to obtain desirable weld metal intensity, generate thick tissue, the toughness deterioration of weld metal in the weld structure easily.On the other hand, content surpasses 2.50%, and tissue thinning effect is saturated, simply hinders the diffusion of C, when generating the island martensite body, significantly hardens owing to solution strengthening makes weld metal, makes the toughness deterioration of weld metal.Therefore, Mn is limited to 1.00～2.50%.Moreover ideal situation is 1.40～2.10%.

Ti:0.030% is above, the quality % of Ti/N ratio: 15～50

Ti is owing to thinning weld metal structure, so add in welding wire in the present invention.Particularly effective after a little while as the Ti content in the steel of materials to be welded.For this weld structure of refinement, need contain more than 0.030%.If less than 0.030%, particularly as the Ti content in the steel of materials to be welded after a little while, the refinement of weld structure is insufficient.If add Ti to weld metal by solder flux, the welding bead appearance degradation is then arranged and take off problems such as slag is bad, in the present invention, add Ti to weld metal and mainly undertaken by welding wire.

Again, because the Ti fix N, adjust solid solution N amount toughness is improved, so Ti content is more than 0.030% in the present invention, and corresponding to the N content in the welding wire, the quality % ratio of Ti/N is adjusted into 15～50.The quality % ratio of Ti/N is as if less than 15, and then the tough property improvement effect of weld metal is little.On the other hand, if the quality % of Ti/N contains Ti, then the toughness deterioration of weld metal than surpassing 50 superfluously.Therefore, limit Ti more than 0.030%, and the quality % of Ti/N is than the scope that is 15～50.Have again, consider that from toughness desirable Ti is below 0.200%.Better situation is below 0.150%.

From Mo:0.10～0.60%, Nb:0.010～0.100%.Select in B:0.0005～0.0100%, Ni:0.20%～2.00% more than a kind or 2 kinds

Mo, Nb, B, Ni have the effect of the toughness that significantly improves weld metal, and the present invention can select as required, contain.Mo, Nb, B are suppressed at the generation of the thick grain boundary ferrite that austenite grain boundary separates out, and the toughness of weld metal is improved.This effect more than containing Mo:0.10%, contain more than the Nb:0.010%, to contain B:0.0005% remarkable when above.On the other hand, content surpasses Mo:0.60%, Nb:0.100%, B:0.0100% respectively, and the tissue of weld metal becomes upper bainite easily, the toughness deterioration.Thus, preferable range is respectively Mo:0.10～0.60%, Nb:0.010～0.100%, B:0.0005～0.0100%.

Again, Ni improves the toughness of ferritic phase, and the toughness of weld metal is improved.This effect is 0.20% remarkable when above at content.On the other hand, one surpasses 2.00%, causes the generation of low temperature crackle easily.Therefore, the Ni preferable range is 0.20%～2.00%.

Remainder beyond the mentioned component is Fe and unavoidable impurities.As unavoidable impurities, below the permission O:0.0050%, below the P:0.020%, below the S:0.010%.

Secondly, welding wire of the present invention is considered from raising wire feeding property, rust-preventing characteristic, is preferably implemented copper facing at welding wire surface.In addition, the low heat input submerged arc welding that welding wire of the present invention promptly is used in the not enough 150kJ/cm of heat input does not have any problem yet, can stablize the weld metal that obtains having excellent in toughness natch.

In addition, when using the welding wire of the invention described above, the solder flux of use does not need special qualification, and generally well-known sintered flux all can use, but the sintered flux of oxide that preferably contains the boron of 0.1～1.0 quality % is good.Provide B by it to weld metal, suppress the alligatoring of tissue, prevent the deterioration of toughness.Secondly, the flux constituent beyond the oxide of boron does not limit especially, but represents that with quality % ideal situation is to contain SiO ₂: 15～28%, MgO:15～38%, iron powder: 15～35%, CaCO ₃: 5～15%, Al ₂O ₃: 5～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond the iron powder: below 8%, even the metal powder beyond the iron powder surpasses the weld metal that 8 quality % also can obtain excellent in toughness, but because the welding material cost increases, the manufacturing expense of welding point uprises, so to contain iron powder metal powder in addition: be advisable below 8%.Secondly, in the present invention, solder flux is not limited thereto, in the solder flux of JISZ3352 defined so long as the solder flux of good manufacturability can not contain iron powder.Have, when adding iron powder in solder flux, ideal situation is to use the following iron powder of N:0.0030 quality % again.The following iron powder of N:0.0030 quality % is advisable with 20～45 quality % that contain the solder flux total amount.

N content one in the iron powder surpasses 0.0030 quality %, and the N content of the weld metal that then obtains increases, and demonstrates to be difficult to the stable tendency of guaranteeing high tenacity.Have, the N content in the iron powder is preferably below 0.0025 quality % again.

Iron powder in the solder flux time helps to increase to molten bath transition, deposited speed, improves welding efficiency and reduce weld heat input in welding.The content of the iron powder that the N:0.0030 quality % in the solder flux is following is as if less than 20 quality %, and above-mentioned effect is little, and on the other hand, content one surpasses the tendency that 45 quality % then demonstrate electric arc instability, welding bead appearance degradation.Thus, the content of the iron powder that N:0.0030 quality % is following is with respect to the solder flux total amount, and preferable range is 20～45 quality %.

In addition, as the 2nd method of the weld metal that obtains the invention described above, by limiting the method that solder flux is formed.At this moment welding wire does not need special qualification, and generally well-known welding wire for submerged-arc welding all can use.

Submerged arc flux of the present invention is a sintered flux, is applicable to the large-line energy submerged arc welding of heat input more than 150kJ/cm well.At first, the reason about the composition that limits submerged arc welding flux of the present invention is illustrated.Be meant quality % when below not having special declaration with respect to the solder flux total amount.Following quality % only represents with %.

Iron powder: 20～45%

Submerged arc flux mainly is made of oxide, fluoride, contains metal powder based on iron powder at the solder flux that is used for the welding of large-line energy and high efficiency.Iron powder in the solder flux time helps to increase to molten bath transition, deposited speed in welding, improves welding efficiency.

Submerged arc flux of the present invention contains 20～45% iron powder with respect to the solder flux total amount.The content of the iron powder in the solder flux is as if less than 20%, and above-mentioned effect is little, and on the other hand, content one surpasses 45% tendency that demonstrates electric arc instability, welding bead appearance degradation.Thus, the content of iron powder is taken as 20～45% with respect to the solder flux total amount.

In the present invention, use N content at the atomized iron powder below 0.0030% as iron powder again.The contained N of iron powder in the solder flux increases the N in the weld metal, reduces the toughness of weld metal.Therefore, in the present invention, the N content of the iron powder in the solder flux is reduced to suitable as far as possible.N content one in the iron powder surpasses 0.0030%, and the N content of the weld metal that then obtains increases, and demonstrates to be difficult to the stable tendency of guaranteeing high tenacity.Therefore, in the present invention, the N content of the iron powder in the solder flux is limited to below 0.0030%.Ideal situation be N content in the iron powder below 0.0025%, consider again serving as better more than 0.0010% from economy.

As the iron powder that has reduced N content, use by molten metal favourable on economy by the atomized iron powder of atomization manufacturing.In addition, by atomized iron powder is used as the solder flux raw material, this benefit of binder amount in the time of reducing the solder flux granulation is arranged also.

Atomized iron powder is that usually the operation by dehydration-drying-pulverizing-classification-processing reduction-pulverizing-classification becomes product with after molten metal spraying, the efflorescence.The N content of common atomized iron powder is about 0.0050%, in order to become the low N atomized iron powder below 0.0030%, will reduce the N amount of molten metal certainly, but need suitably be adjusted at reduction temperature in the processing reduction operation, cooling velocity etc.

B compound: convert 0.03～0.30% with B

B transition in weld metal when welding has the thick ferritic generation that suppresses to be created on austenite grain boundary in weld metal, make the effect of the toughness raising of weld metal, and B can reach this effect at an easy rate.This effect is by containing the convert B compound more than 0.03% that surpasses the solder flux total amount and more remarkable of useful B.On the other hand, convert and account for 0.30% B compound of solder flux total amount, the tendency of weld metal toughness deterioration is then arranged if contain useful B.

(A) group and (B) group in 1 group or 2 groups

(A) group: Mo powder.In molybdenum-iron powder and the Mo compound powder more than a kind or 2 kinds: convert to add up to 0.2～2.0% with Mo

(B) group: in Nb powder, ferro-niobium powder and the Nb compound powder more than a kind or 2 kinds: convert to add up to 0.02～0.15% with Nb

(A) group is to make that to contain Mo, (B) group in the weld metal be to make the supply source that contains Nb in the weld metal.Mo, Nb all transition in weld metal when welding, in weld metal, has the thick ferritic generation that suppresses to be created on austenite grain boundary, make the effect of the toughness raising of weld metal, 1 group or 2 groups that selects can be selected, be contained to above-mentioned effect as required from (A) group, (B) group.

Above-mentioned effect converting with Mo more than a kind or 2 kinds in Mo powder, molybdenum-iron powder and the Mo compound powder of (A) group amounts to 0.2% or more, amounting to 0.02% with the Nb conversion more than a kind or 2 kinds and become remarkable when above in Nb powder, ferro-niobium powder and the Nb compound powder of (B) group.On the other hand, if excess contains respectively (A) group and (B) group, wherein (A) group: will convert to add up to surpass 2.0% with Mo more than a kind or 2 kinds in Mo powder, molybdenum-iron powder and the Mo compound powder; (B) group: with adding up to above 0.15% with the Nb conversion more than a kind or 2 kinds in Nb powder, ferro-niobium powder and the Nb compound powder, then the tissue of weld metal becomes upper bainite easily, and the tendency of the toughness deterioration of weld metal is arranged.

On the mentioned component basis also from SiO ₂: 10～28%, CaCO ₃: 5～15%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, atomized iron powder, the metal powder beyond Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds

Solder flux of the present invention above-mentioned iron powder (atomized iron powder), B compound powder, and Mo powder, molybdenum-iron powder, Mo compound powder in the basis more than a kind or 2 kinds more than a kind or 2 kinds, in the Nb powder, ferro-niobium powder, Nb compound powder on, ideal situation is also to contain from SiO ₂, CaCO ₃, MgO, Al ₂O ₃, TiO ₂, CaF ₂And select in the metal powder beyond the atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder, ferro-niobium powder more than a kind or 2 kinds.

SiO ₂As slag former is active ingredient, for the viscosity of adjusting slag preferably contains it.SiO ₂Contain quantity not sufficient 10%, the fusing point of the slag of generation is tending towards rising, on the other hand, it is low excessively that content one surpasses 28% fusing point, the welding bead outward appearance is disorderly easily, the oxygen amount of weld metal increases in addition, the toughness of weld metal is tending towards deterioration.Therefore, SiO ₂Be preferably 10～28%.

CaCO ₃In welding, decompose, become CaO and CO ₂By this CO ₂When gas isolates weld metal in the gas from the outside, reduce the hydrogen dividing potential drop in the welding atmosphere, play effective function in the weld metal for preventing that hydrogen from dissolving in.In addition, CaO is an alkaline components, has the fusing point that improves slag, improves the effect of the toughness of weld metal.

CaCO ₃Content if less than 5%, can't see as described above by CO ₂The protection effect that gas brings has the tendency of anti-hydrogen induced cracking reduction.On the other hand, its content one surpasses 15%, CO ₂The generating capacity of gas increases, welding procedure, figuration of bead reduction.Therefore, CaCO ₃Preferable range be 5～15%.

MgO has the effect that prevents the solder flux excess flow, has the effect of the weld bead shape in the stable large-line energy welding.Again, MgO is the basicity that increases slag, reduces the oxygen content in the weld metal, improves the useful component of the toughness of weld metal.The content of MgO is if less than 15% be can't see above-mentioned effect, and on the other hand, content one surpasses 38%, then has fusing point too to rise, the tendency of welding bead appearance degradation.Therefore, the preferable range of MgO is 15～38%.

Al ₂O ₃Owing to not reducing the fusing point that viscosity improves slag, so be the composition of effectively adjusting the slag fusing point.Al ₂O ₃Content if less than 3%, can't see above-mentioned effect, on the other hand, content one surpasses 20%, then the fusing point of slag too rises, and causes the inhomogeneous and appearance degradation of weld width.Therefore, Al ₂O ₃Preferable range be 3～20%.

TiO ₂When improving the flowability of slag, improving the slag removability of slag, in the electric arc cavity,, carry out the transition in the weld metal as Ti by partial reduction, the toughness of improving weld metal is played useful effect.TiO ₂Content if less than 2%, can't see above-mentioned effect, on the other hand, content one surpasses 10%, then demonstrates the tendency of welding bead appearance degradation.Therefore, TiO ₂Preferable range be 2～10%.

CaF ₂Do not improve fusing point, can increase the basicity of slag, effective to the oxygen amount of adjusting weld metal.CaF ₂Content if less than 2%, this effect is little, on the other hand, its content one surpasses 10%, then the viscosity of slag too reduces, the welding bead outward appearance worsens.Therefore, CaF ₂Preferable range be 2～10%.

Metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder adds as deoxidier or alloying element source, but if its content is difficult to guarantee the toughness of weld metal, the tendency that has the welding bead outward appearance to worsen simultaneously less than 2%.On the other hand, its content one surpasses 8%, and then the oxygen quantitative change of weld metal is low, because weld structure becomes bainite or martensite is the tissue of main body, so the tendency that has weld metal toughness to descend.Therefore, the preferable range of the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder is 2～8%.As such metal powder ferromanganese, ferrosilicon, ferrotianium, manganese, titanium etc. are arranged.Secondly, metal powder can be the form beyond the powder, can be paper tinsel shape, needle-like.

Solder flux of the present invention is to fire after above-mentioned solder flux raw material is mixed together stirring, granulation by the ormal weight of above-mentioned scope batching and binding agent.Do not limit especially as prilling process, but use rotary type comminutor, extrusion formula comminutor etc. more suitable.Carry out the whole grain of gumming dirt, pulverizing big particle etc. after the granulation and handle, the desirable average grain diameter of particle is 0.075～5mm scope.

Again, as mixed liquor of the aqueous solution, sodium silicate aqueous solution, potassium silicate aqueous solution and the sodium silicate aqueous solution and the potassium silicate aqueous solution of binding agent preferably polyethylene alcohol etc. etc.Desirable content of binder is that every solder flux raw material total amount 1kg adds about 50～300cc.In addition, the low heat input submerged arc welding that solder flux of the present invention promptly is used in the not enough 150kJ/cm of heat input does not have any problem yet, can stablize the weld metal that obtains having excellent in toughness certainly.

Again, when using the solder flux of the invention described above, the welding wire of use does not need special qualification, and generally well-known welding wire for submerged-arc welding all can use.

Manufacture method about the large-line energy submerged-arc welding welding point of weld metal zone good-toughness is illustrated below.The manufacture method of large-line energy submerged-arc welding welding point of the present invention, use the poor steel of Ti, Nb as soldered material, when carrying out solder joints, effective especially to the weld metal that obtains high tenacity by the large-line energy submerged arc welding of heat input more than 150kJ/cm.

The steel that use as soldered material be have Ti content below the 0.006 quality %, Nb content below the 0.012 quality %, the steel formed of the desirable mother metal of N content below 0.0055 quality %.As other composition with contain C:0.07～0.18%, below the Si:0.40%, Mn:1.00～1.60%, below the P:0.020%, below the S:0.010%, perhaps also contain below the Al:0.050% and be advisable.Except that mentioned component, can contain V.Secondly, said steel are meant the steel that comprise steel plate, shaped steel, steel pipe, bar steel among the present invention.

After above-mentioned steel being implemented the groove processing of defined shape, in this groove, scatter solder flux, use above-mentioned large-line energy welding wire for hidden arc welding, by the large-line energy submerged-arc welding solder bond of heat input more than 150kJ/cm.

Submerged arc welding among the present invention does not need special qualification, and comprising the generally well-known welding method that multiple electrode submerged arc welding connects can both be suitable for.In addition, welding condition does not need special qualification yet.

Combination with such materials to be welded, welding material is made welding point (Welding Structure) by the large-line energy submerged-arc welding solder joints of heat input more than 150kJ/cm.The weld metal of the welding point that obtains (Welding Structure) is the weld metal of high tenacity.

(embodiment 1)

The 490MPa grade steel plate (thickness of slab: 25mm, 40mm) that mother metal shown in the his-and-hers watches 1 is formed is implemented the groove processing of shape shown in Figure 1A, Figure 1B, has made welding point by the submerged arc welding of 1 passage.Groove during thickness of slab 25mm is shaped as レ type groove, and bevel angle is 40 °, and root face is 2mm.Again, steel plate when being 40mm thick groove be shaped as Y type groove, bevel angle is 35 °, root face is 3mm.

The bipolar electrode submerged arc welding machine is used in submerged arc welding, and the welding wire of forming shown in the use table 3 under the welding condition shown in the table 2 carries out.Again, the solder flux that uses is the commercially available iron powder sintered flux of the boron oxide that contains 0.4 quality % of the composition shown in the table 4.Secondly, the iron powder that contains in the solder flux uses with the iron powder of sponge iron as raw material.Weld heat input is 153kJ/cm at thickness of slab during for 25mm, is 270kJ/cm at thickness of slab during for 40mm.

The welding point that obtains is like this prepared sample from Fig. 2 A of the central part of welding total length, the position shown in Fig. 2 B, investigate hot strength, the toughness of weld metal.Tension test is implemented according to the regulation of JIS Z3112 according to the regulation of JIS Z3111, impact test, and the summer when having obtained hot strength TS and 0 ℃ ,-20 ℃ is than absorbing merit value vE ₀, vE _-20

It the results are shown in table 5.

Example of the present invention can both obtain having the vE of weld metal ₀More than 27J and the welding point of the equal good toughness of the mean level of mother metal standard.In addition, the welding point (welding point No.3, No.4, No.5) that uses the welding wire contain Mo, Nb in the scope of the invention to obtain has the vE of weld metal _-20The good toughness that surpasses 27J.

On the other hand, exceed the comparative example (welding point No.6) of the scope of the invention, the vE of weld metal for the N content of welding wire ₀Not enough 27J, the toughness deterioration.Again, hang down the comparative example (welding point No.7) of scope of the present invention for the Ti content of welding wire, organize thick, the vE of weld metal ₀Not enough 27J, the toughness deterioration.Hang down the comparative example (welding point No.6, No.7, No.8) of scope of the present invention, the vE of weld metal for the Ti/N of welding wire again, ₀Not enough 27J, the toughness deterioration.Again, exceed the comparative example (welding point No.9) of scope of the present invention for the Ti content of welding wire, tissue becomes the tissue that upper bainite is a main body, the vE of weld metal ₀Not enough 27J, the toughness deterioration.Again, for the Mn content of welding wire hang down the comparative example (welding point No.10) of scope of the present invention, the Si content of welding wire exceeds the comparative example of the scope of the invention (welding point No.11), the ferrite alligatoring of weld metal, vE ₀Not enough 27J, the toughness deterioration of weld metal.

Again, quality % ratio and the grain boundary ferrite growing amount of the composition of table 6 expression weld metal, the B/N in the weld metal.Grain boundary ferrite growing amount in the weld metal of example of the present invention all is below the 15 area %, can obtain the vE of weld metal ₀Welding point more than 27J with excellent in toughness.Again, use contains the Mo in the scope of the invention, the welding wire of Nb, grain boundary ferrite growing amount in the weld metal of the B/N quality % ratio welding point (welding point No.3, No.4, No.5) within the scope of the invention in the weld metal is below the 10 area %, has the vE of weld metal _-20The good toughness that surpasses 27J.

(embodiment 2)

The groove that the 490MPa grade steel plate (thickness of slab t:40mm) that mother metal shown in the his-and-hers watches 7 is formed, building structure are implemented shape shown in Figure 3 with TMCP steel plate (thickness of slab t:60mm) is processed, and has made welding point by the submerged arc welding of 1 passage.Groove is shaped as the Y type, and bevel angle is 35 °, and root face d (mm) is 2mm when thickness of slab t:40mm, is 3mm when thickness of slab t:60mm.

The bipolar electrode submerged arc welding machine is used in submerged arc welding, and the welding wire that the welding wire under the welding condition shown in the table 8 shown in the use table 9 is formed carries out.Again, use the solder flux contain boron oxide and iron powder, solder flux is to make to resemble to prepare burden forming shown in the table 10 and sodium metasilicate burns till under the condition of 500 ℃ * 15min after being mixed together stirring, granulation, and particle diameter is below the 3mm.Add the iron powder of nitrogen content shown in the iron powder use table 11 in the solder flux to again.Weld heat input is 269kJ/cm at thickness of slab during for 40mm, is 549kJ/cm at thickness of slab during for 60mm.

Same to the welding point and the embodiment 1 that obtain like this, prepare sample from Fig. 2 A, the position shown in Fig. 2 B of the central part of welding total length, investigate hot strength, the toughness of weld metal.Again and embodiment 1 same, tension test is implemented according to the regulation of JIS Z3112 according to the regulation of JIS Z3111, impact test, the summer when having obtained hot strength TS and 0 ℃ ,-20 ℃ is than absorbing merit value vE ₀, vE _-20

It the results are shown in table 12.

For the welding point of welding wire that has used example of the present invention and solder flux, the vE of weld metal ₀Reach more than the 100J during at thickness of slab, reach more than the 47J vE of weld metal during for 60mm at thickness of slab for 40mm _-20Reach more than the 80J during at thickness of slab, reach more than the 50J during for 60mm, can obtain having the welding point of excellent in toughness at thickness of slab for 40mm.

Again, quality % ratio and the grain boundary ferrite growing amount of the composition of table 13 expression weld metal, the B/N in the weld metal.Use welding wire of the present invention and solder flux, grain boundary ferrite growing amount in the weld metal of the B/N quality % ratio welding point (welding point No.2-1, No.2-2, No.2-3, No.2-4, No.2-5) within the scope of the invention in the weld metal is below the 10 area %, can obtain having the weld metal of very good toughness.

(embodiment 3)

The bipolar electrode submerged arc welding machine is used in submerged arc welding, and the solder flux of forming shown in the welding wire that the welding wire under the welding condition shown in the table 14 shown in the use table 15 is formed, the table 16 carries out.

Again, (addition: the about 200cc of every 1kg solder flux) burn till under the condition of 500 ℃ * 15min after being mixed together stirring, granulation, particle diameter is below the 3mm for the such preparation raw material of solder flux composition shown in table 16 and the sodium silicate aqueous solution.Again, the chemical composition in the table 16 adds up to less than 100 quality %, but remainder is sodium metasilicate solid state component and unavoidable impurities.Again, the iron powder that adds in the solder flux is an atomized iron powder, uses the atomized iron powder of the nitrogen content shown in the table 17.Weld heat input is 269kJ/cm at thickness of slab during for 40mm, is 521kJ/cm at thickness of slab during for 60mm.

The welding point that obtains is like this prepared sample from Fig. 2 A of the central part of welding total length, the position shown in Fig. 2 B, investigate hot strength, the toughness of weld metal.Tension test prepares sample from the position of Fig. 2 A, implements according to the regulation of JIS Z3111, has obtained hot strength TS, and impact test prepares sample from the position of Fig. 2 B, implements according to the regulation of JIS Z3112, and the summer when having obtained 0 ℃ is than absorbing merit value vE ₀

It the results are shown in table 18.

Example of the present invention all satisfies the vE of weld metal ₀More than 27J, can obtain having the welding point of excellent in toughness.The toughness of weld metal that departs from the comparative example of the scope of the invention reduces.

Again, quality % ratio and the grain boundary ferrite growing amount of the composition of table 19 expression weld metal, the B/N in the weld metal.Having used the grain boundary ferrite growing amount in the weld metal of solder flux of example of the present invention is below the 15.0 area %, can obtain having the weld metal of excellent in toughness.Grain boundary ferrite growing amount in the weld metal of the welding point (welding point No.3-5, No.3-9, No.3-10) within the scope of the invention of the B/N quality % in the weld metal is below the 10 area %, has better toughness.

According to the present invention, when adopting the poor steel of large-line energy submerged-arc welding welding Ti, the Nb etc. of weld heat input more than 150kJ/cm, also can stablize the weld metal that obtains having excellent in toughness, can significantly improve welding efficiency, the special result on the acquisition industry.

Table 1

Steel plate No	Grade	Thickness of slab mm	Chemical composition (quality %)
			Chemical composition (quality %)										C	Si	Mn	P	S	Ti	Nb	N	Al	V
			1	SN-490C	25	0.14	0.35	1.48	0.015	0.003	0.005	0.003	C	Si	Mn	P	S	Ti	Nb	N	Al	V	0.0030	0.030	-
2	SN-490C	40	1	SN-490C	25	0.14	0.35	1.48	0.015	0.003	0.005	0.003	0.13	0.33	1.36	0.015	0.003	0.003	0.008	0.0040	0.021	0.030	0.0030	0.030	-

Table 3

Welding wire No	Chemical composition (quality %)												Remarks
	Chemical composition (quality %)													C	Si	Mn	P	S	Ti	N	Ti/N	Mo	Nb	B	Ni
	A	0.06	0.05	1.80	0.009	0.005	0.100	0.0022	45	-	-	-		C	Si	Mn	P	S	Ti	N	Ti/N	Mo	Nb	B	Ni	-	Example of the present invention
B	A	0.06	0.05	1.80	0.009	0.005	0.100	0.0022	45	-	-	-	0.04	0.35	2.20	0.015	0.006	0.080	0.0032	25	-	-	-	-	Example of the present invention	-	Example of the present invention
B	C	0.05	0.30	1.50	0.010	0.005	0.030	0.0020	15	0.50	-	-	0.04	0.35	2.20	0.015	0.006	0.080	0.0032	25	-	-	-	-	Example of the present invention	0.5	Example of the present invention
D	C	0.05	0.30	1.50	0.010	0.005	0.030	0.0020	15	0.50	-	-	0.08	0.03	1.20	0.009	0.003	0.080	0.0024	33	0.20	-	0.0010	-	Example of the present invention	0.5	Example of the present invention
D	E	0.07	0.02	2.40	0.008	0.002	0.040	0.0025	16	-	0.080	-	0.08	0.03	1.20	0.009	0.003	0.080	0.0024	33	0.20	-	0.0010	-	Example of the present invention	-	Example of the present invention
F	E	0.07	0.02	2.40	0.008	0.002	0.040	0.0025	16	-	0.080	-	0.06	0.01	1.90	0.016	0.003	0.050	0.0040	13	-	-	-	-	Comparative example	-	Example of the present invention
F	G	0.06	0.30	1.80	0.016	0.003	0.020	0.0030	7	-	-	-	0.06	0.01	1.90	0.016	0.003	0.050	0.0040	13	-	-	-	-	Comparative example	-	Comparative example
H	G	0.06	0.30	1.80	0.016	0.003	0.020	0.0030	7	-	-	-	0.07	0.20	1.80	0.015	0.003	0.040	0.0030	13	-	-	-	-	Comparative example	-	Comparative example
H	I	0.07	0.20	1.80	0.015	0.003	0.22	0.0031	71	-	-	-	0.07	0.20	1.80	0.015	0.003	0.040	0.0030	13	-	-	-	-	Comparative example	-	Comparative example
J	I	0.07	0.20	1.80	0.015	0.003	0.22	0.0031	71	-	-	-	0.06	0.02	0.80	0.012	0.003	0.040	0.0024	17	-	-	-	-	Comparative example	-	Comparative example
J	K	0.08	0.50	1.90	0.010	0.004	0.040	0.0025	16	-	-	-	0.06	0.02	0.80	0.012	0.003	0.040	0.0024	17	-	-	-	-	Comparative example	-	Comparative example

Table 2

Welding condition No	Welding condition								Remarks
	Welding condition									The preceding utmost point			The back utmost point			Speed of welding cm/min	Heat input kJ/cm
	Gage of wire mm	Electric current A	Voltage V	Gage of wire mm	Electric current A	Voltage V				The preceding utmost point			The back utmost point
	Gage of wire mm	Electric current A	Voltage V	Gage of wire mm	Electric current A	Voltage V	a	6.4		1600	34	6.4	1160	42	39			153	Thickness of slab 25mm
b	6.4	1800	35	6.4	1400	45	a	6.4	28	1600	34	6.4	1160	42	39	270	Thickness of slab 40mm	153	Thickness of slab 25mm

Table 4

Solder flux No	Chemical composition (quality %)
	Chemical composition (quality %)									SiO ₂	MgO	CaCO ₂	Al ₂O ₃	TiO ₂	CaF ₃	B ₂O ₄	Iron powder	Metal powder beyond the iron powder
	FL									SiO ₂	MgO	CaCO ₂	Al ₂O ₃	TiO ₂	CaF ₃	B ₂O ₄	Iron powder	Metal powder beyond the iron powder
	FL	20	20	9	8	5	4	0.4	25	5

Table 5

Welding point No	The welding combination				Toughness		Hot strength	Remarks
	The welding combination				Toughness		Hot strength		Steel No.	Welding wire No.	Solder flux No	Welding condition	vE ₀ (J)	vE _-20 (J)	TS (MPa)
	1	1	A	FL	a	45	27		Steel No.	Welding wire No.	Solder flux No	Welding condition	vE ₀ (J)	vE _-20 (J)	TS (MPa)	589	Example of the present invention
2	1	1	A	FL	a	45	27	2	B	FL	b	41	25	622	Example of the present invention	589	Example of the present invention
2	3	2	C	FL	b		120	2	B	FL	b	41	25	622	Example of the present invention	74	623	Example of the present invention
4	3	2	C	FL	b		120	1	D	FL	a	81	53	577	Example of the present invention	74	623	Example of the present invention
4	5	1	E	FL	a	59	38	1	D	FL	a	81	53	577	Example of the present invention	644	Example of the present invention
6	5	1	E	FL	a	59	38	1	F	FL	a	25	16	589	Comparative example	644	Example of the present invention
6	7	2	G	FL	b	23	11	1	F	FL	a	25	16	589	Comparative example	586	Comparative example
8	7	2	G	FL	b	23	11	2	H	FL	b	24	12	604	Comparative example	586	Comparative example
8	9	1	I	FL	a	26	16	2	H	FL	b	24	12	604	Comparative example	640	Comparative example
10	9	1	I	FL	a	26	16	1	J	FL	a	22	11	478	Comparative example	640	Comparative example
10	11	2	K	FL	b	24	17	1	J	FL	a	22	11	478	Comparative example	608	Comparative example

Table 6

Welding point No.	C	Si	Mn	Ti	N	Mo	Nb	Ni	B	B/N quality % ratio in the weld metal	Grain boundary ferrite growing amount in the weld metal (area %)	Remarks
Welding point No.	C	Si	Mn	Ti	N	Mo	Nb	Ni	B	B/N quality % ratio in the weld metal		Remarks	1	0.10	0.31	1.46	0.030	0.0031	-	0.002	-	0.0017	0.55	13.1	Example of the present invention
2	0.09	0.42	1.56	0.024	0.0039	-	0.003	-	0.0020	0.51	11.4	Example of the present invention	1	0.10	0.31	1.46	0.030	0.0031	-	0.002	-	0.0017	0.55	13.1	Example of the present invention
2	0.09	0.42	1.56	0.024	0.0039	-	0.003	-	0.0020	0.51	11.4	Example of the present invention	3	0.09	0.39	1.38	0.005	0.0031	0.20	0.003	0.19	0.0022	0.71	7.8	Example of the present invention
4	0.11	0.33	1.33	0.025	0.0032	0.09	0.003	-	0.0026	0.81	8.2	Example of the present invention	3	0.09	0.39	1.38	0.005	0.0031	0.20	0.003	0.19	0.0022	0.71	7.8	Example of the present invention
4	0.11	0.33	1.33	0.025	0.0032	0.09	0.003	-	0.0026	0.81	8.2	Example of the present invention	5	0.10	0.30	1.77	0.013	0.0030	-	0.034	-	0.0018	0.60	9.6	Example of the present invention
6	0.10	0.28	1.52	0.010	0.0040	-	0.002	-	0.0016	0.40	18.7	Comparative example	5	0.10	0.30	1.77	0.013	0.0030	-	0.034	-	0.0018	0.60	9.6	Example of the present invention
6	0.10	0.28	1.52	0.010	0.0040	-	0.002	-	0.0016	0.40	18.7	Comparative example	7	0.10	0.40	1.44	0.004	0.0036	-	0.002	-	0.0017	0.47	17.5	Comparative example
8	0.11	0.35	1.39	0.008	0.0039	-	0.004	-	0.0019	0.49	16.8	Comparative example	7	0.10	0.40	1.44	0.004	0.0036	-	0.002	-	0.0017	0.47	17.5	Comparative example
8	0.11	0.35	1.39	0.008	0.0039	-	0.004	-	0.0019	0.49	16.8	Comparative example	9	0.11	0.36	1.46	0.071	0.0033	-	0.002	-	0.0017	0.52	15.2	Comparative example
10	0.10	0.30	1.06	0.011	0.0033	-	0.002	-	0.0017	0.52	23.1	Comparative example	9	0.11	0.36	1.46	0.071	0.0033	-	0.002	-	0.0017	0.52	15.2	Comparative example
10	0.10	0.30	1.06	0.011	0.0033	-	0.002	-	0.0017	0.52	23.1	Comparative example	11	0.10	0.52	1.47	0.007	0.0034	-	0.003	-	0.0018	0.53	28.3	Comparative example

Table 7

Steel plate No	Grade	Thickness of slab mm	Chemical composition (quality %)
			Chemical composition (quality %)										C	Si	Mn	P	S	Ti	Nb	N	Al	V
			3	SN-490C	40	0.13	0.33	1.36	0.015	0.003	0.003	0.008	C	Si	Mn	P	S	Ti	Nb	N	Al	V	0.0040	0.021	0.030
4	The TMCP steel	60	3	SN-490C	40	0.13	0.33	1.36	0.015	0.003	0.003	0.008	0.13	0.26	1.45	0.011	0.002	0.006	0.010	0.0032	0.026	0.002	0.0040	0.021	0.030

Table 8

Welding condition No	Welding condition								Remarks
	Welding condition									The preceding utmost point			The back utmost point			Speed of welding cm/min	Heat input kJ/cm
	Gage of wire mm	Electric current A	Voltage V	Gage of wire mm	Electric current A	Voltage V				The preceding utmost point			The back utmost point
	Gage of wire mm	Electric current A	Voltage V	Gage of wire mm	Electric current A	Voltage V	c	6.4		1800	34	6.4	1400	46	28			269	Thickness of slab 40mm
d	6.4	2300	38	6.4	1800	48	c	6.4	19	1800	34	6.4	1400	46	28	549	Thickness of slab 60mm	269	Thickness of slab 40mm

Table 10

Solder flux No	Chemical composition (quality %)
	Chemical composition (quality %)									SiO ₂	MgO	CaCO ₃	Al ₂O ₃	TiO ₂	CaF ₂	B ₂O ₃	Iron powder *	Metal powder beyond the iron powder
	FL-2	21	25	10	8	6	4	0.3	β：20	SiO ₂	MgO	CaCO ₃	Al ₂O ₃	TiO ₂	CaF ₂	B ₂O ₃	Iron powder *	Metal powder beyond the iron powder	5
FL-3	FL-2	21	25	10	8	6	4	0.3	β：20	19	21	10	7	6	4	0.4	α：23	5	5
FL-3	FL-4	19	21	10	7	6	4	0.4	β：23	19	21	10	7	6	4	0.4	α：23	5	5
FL-5	FL-4	19	21	10	7	6	4	0.4	β：23	19	21	10	7	6	4	0.4	γ：23	5	5
FL-5	FL-6	11	16	6	4	3	3	0.6	β：47	19	21	10	7	6	4	0.4	γ：23	5	6
FL-7	FL-6	11	16	6	4	3	3	0.6	β：47	20	16	9	17	7	6	0.3	β：16	3	6

*) with reference to table 11

Table 11

Iron powder No.	N content (quality %)
Iron powder No.	N content (quality %)	α	0.0020
β	0.0028	α	0.0020
β	0.0028	γ	0.0045

Table 9

Welding wire	Chemical composition (quality %)												Remarks
Welding wire	Chemical composition (quality %)													No	C	Si	Mn	P	S	Ti	N	Ti/N	Mo	Nb	B	Ni
L	0.05	0.33	2.08	0.012	0.005	0.079	0.0032	25	-	-	-	-		No	C	Si	Mn	P	S	Ti	N	Ti/N	Mo	Nb	B	Ni	Example of the present invention

Table 13

Welding point No.	C	Si	Mn	Ti	N	Mo	Nb	Ni	B	B/N quality % ratio in the weld metal	Grain boundary ferrite growing amount in the weld metal (area %)	Remarks
Welding point No.	C	Si	Mn	Ti	N	Mo	Nb	Ni	B	B/N quality % ratio in the weld metal		Remarks	2-1	0.09	0.46	1.44	0.018	0.0023	0.25	0.004	-	0.0018	0.78	1.2	Example of the present invention
2-2	0.09	0.45	1.48	0.020	0.0024	0.26	0.004	-	0.0025	1.04	7.9	Example of the present invention	2-1	0.09	0.46	1.44	0.018	0.0023	0.25	0.004	-	0.0018	0.78	1.2	Example of the present invention
2-2	0.09	0.45	1.48	0.020	0.0024	0.26	0.004	-	0.0025	1.04	7.9	Example of the present invention	2-3	0.10	0.39	1.53	0.021	0.0031	0.12	0.005	-	0.0020	0.65	9.0	Example of the present invention
2-4	0.09	0.38	1.51	0.023	0.0036	-	0.011	-	0.0022	0.61	9.5	Example of the present invention	2-3	0.10	0.39	1.53	0.021	0.0031	0.12	0.005	-	0.0020	0.65	9.0	Example of the present invention
2-4	0.09	0.38	1.51	0.023	0.0036	-	0.011	-	0.0022	0.61	9.5	Example of the present invention	2-5	0.10	0.41	1.50	0.021	0.0045	-	0.005	0.05	0.0027	0.60	9.9	Example of the present invention
2-6	0.09	0.48	1.47	0.019	0.0029	-	0.004	-	0.0015	0.52	14.7	Example of the present invention	2-5	0.10	0.41	1.50	0.021	0.0045	-	0.005	0.05	0.0027	0.60	9.9	Example of the present invention

Table 12

Welding point No	The welding combination				Toughness		Hot strength	Remarks
	The welding combination				Toughness		Hot strength		Steel No.	Welding wire No.	Solder flux No	Welding condition	vE ₀ (J)	vE _-20 (J)	TS (MPa)
	2-1	3	L	FL-2	c	120	82		Steel No.	Welding wire No.	Solder flux No	Welding condition	vE ₀ (J)	vE _-20 (J)	TS (MPa)	624	Example of the present invention
2-2	2-1	3	L	FL-2	c	120	82	3	L	FL-3	c	102	80	614	Example of the present invention	624	Example of the present invention
2-2	2-3	4	L	FL-4	d	81	54	3	L	FL-3	c	102	80	614	Example of the present invention	619	Example of the present invention
2-4	2-3	4	L	FL-4	d	81	54	4	L	FL-5	d	68	50	609	Example of the present invention	619	Example of the present invention
2-4	2-5	4	L	FL-6	d	51	30	4	L	FL-5	d	68	50	609	Example of the present invention	599	Example of the present invention
2-6	2-5	4	L	FL-6	d	51	30	3	L	FL-7	c	49	28	526	Example of the present invention	599	Example of the present invention

Table 14

Welding condition No	Welding condition								Remarks
	Welding condition									The preceding utmost point			The back utmost point			Speed of welding cm/min	Heat input kJ/cm
	Gage of wire mm	Electric current A	Voltage V	Gage of wire mm	Electric current A	Voltage V				The preceding utmost point			The back utmost point
	Gage of wire mm	Electric current A	Voltage V	Gage of wire mm	Electric current A	Voltage V	e	6.4		1800	34	6.4	1400	46	28			269	Thickness of slab 40mm
f	6.4	2300	38	6.4	1800	48	e	6.4	20	1800	34	6.4	1400	46	28	521	Thickness of slab 60mm	269	Thickness of slab 40mm

[table 15] table 15

Welding wire No	Chemical composition (quality %)
	Chemical composition (quality %)							C	Si	Mn	P	Ti	N	Nb
	M	0.04	0.35	2.11	0.004	-	0.0040	C	Si	Mn	P	Ti	N	Nb	-

Table 16

Solder flux No	Chemical composition (quality %)											Remarks
	Chemical composition (quality %)												SiO ₂	MgO	CaCO ₃	Al ₂O ₃	TiO ₂	CaF ₂	Iron powder kind: content	Metal powder kind beyond the iron powder: content	B ^***Kind: content	Mo ^*Kind: content	Nb ^*Kind: content
	F1	22	25	10	8	6	4	B：13	Ferrosilicon: 5	B ₂O ₃：0.03	-		SiO ₂	MgO	CaCO ₃	Al ₂O ₃	TiO ₂	CaF ₂	Iron powder kind: content	Metal powder kind beyond the iron powder: content	B ^***Kind: content	Mo ^*Kind: content	Nb ^*Kind: content	-	Comparative example
F2	F1	22	25	10	8	6	4	B：13	Ferrosilicon: 5	B ₂O ₃：0.03	-	20	23	10	7	6	4	A：20	Ferrosilicon: 5	B ₂O ₃：0.05	-	-	Example of the present invention	-	Comparative example
F2	F3	20	23	10	7	6	4	B：20	Ferromanganese: 5	B ₂O ₃：0.05	-	20	23	10	7	6	4	A：20	Ferrosilicon: 5	B ₂O ₃：0.05	-	-	Example of the present invention	-	Example of the present invention
F4	F3	20	23	10	7	6	4	B：20	Ferromanganese: 5	B ₂O ₃：0.05	-	20	23	10	7	6	4	C：20	Ferromanganese: 5	B ₂O ₃：0.05	-	-	Comparative example	-	Example of the present invention
F4	F5	15	20	9	4	10	4	B：30	Ferrosilicon: 3	B ₂O ₃：0.08	Mo powder: 1.0	20	23	10	7	6	4	C：20	Ferromanganese: 5	B ₂O ₃：0.05	-	-	Comparative example	Fe-Nb：0.1	Example of the present invention
F6	F5	15	20	9	4	10	4	B：30	Ferrosilicon: 3	B ₂O ₃：0.08	Mo powder: 1.0	15	20	9	6	5	4	B：30	Ferrosilicon: 3	-	Mo powder: 1.5	-	Example of the present invention	Fe-Nb：0.1	Example of the present invention
F6	F7	15	20	9	6	5	4	B：30	Ferrosilicon: 3	B ₂O ₃：0.11	-	15	20	9	6	5	4	B：30	Ferrosilicon: 3	-	Mo powder: 1.5	-	Example of the present invention	-	Example of the present invention
F8	F7	15	20	9	6	5	4	B：30	Ferrosilicon: 3	B ₂O ₃：0.11	-	15	20	9	6	5	4	B：30	Manganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	Fe-Nb：0.1	Example of the present invention	-	Example of the present invention
F8	F9	12	17	8	5	4	3	A：40	Ferromanganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	15	20	9	6	5	4	B：30	Manganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	Fe-Nb：0.1	Example of the present invention	Fe-Nb：0.05	Example of the present invention
F10	F9	12	17	8	5	4	3	A：40	Ferromanganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	12	17	8	5	4	3	B：40	Ferromanganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	Nb powder: 0.05	Example of the present invention	Fe-Nb：0.05	Example of the present invention
F10	F11	12	17	8	5	4	3	C：40	Manganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	12	17	8	5	4	3	B：40	Ferromanganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	Nb powder: 0.05	Example of the present invention	Nb powder: 0.05	Comparative example
F12	F11	12	17	8	5	4	3	C：40	Manganese: 3	B ₂O ₃：0.06	Fe-Mo：0.6	11	16	6	4	3	3	B： 47	Ferromanganese: 3	B ₂O ₃：0.06	-	-	Comparative example	Nb powder: 0.05	Comparative example
F12	F13	14	20	12	5	9	3	A：25	Ferrosilicon: 4	-	Fe-Mo：1.5	11	16	6	4	3	3	B： 47	Ferromanganese: 3	B ₂O ₃：0.06	-	-	Comparative example	-	Example of the present invention
F14	F13	14	20	12	5	9	3	A：25	Ferrosilicon: 4	-	Fe-Mo：1.5	14	20	12	5	9	3	A：25	Ferrosilicon: 4	-	-	Fe-Nb：0.12	Example of the present invention	-	Example of the present invention

*) content that converts with each element

*) B ₂O ₃Be to contain B ₂O ₃Glassy compound

Table 17

Atomized iron powder No.	N content (quality %)
Atomized iron powder No.	N content (quality %)	A	0.0019
B	0.0027	A	0.0019
B	0.0027	C	0.0040

Table 18

Welding point No	Rong Jie Group closes sweet				Toughness	Hot strength	The welding bead outward appearance	Remarks
	Rong Jie Group closes sweet				Toughness	Hot strength			Steel No.	Welding wire No.	Solder flux No	Welding condition	vE ₀ (J)	TS (MPa)
	3-1	3	M	F1	e				Steel No.	Welding wire No.	Solder flux No	Welding condition	vE ₀ (J)	TS (MPa)	25	598	Fuse bad	Comparative example
3-2	3-1			F1			F2	51	603	Well	Example of the present invention				25	598	Fuse bad	Comparative example
3-2	3-3			F3			F2	51	603	Well	Example of the present invention	36	607	Well	Example of the present invention
3-4	3-3			F3			F4	22	542	Well	Comparative example	36	607	Well	Example of the present invention
3-4	3-5			3			F4	22	542	Well	Comparative example	M	F5	e	63	571	Well	Example of the present invention
3-6	3-5	3	M	3	F6	e	28	566	Well	Example of the present invention		M	F5	e	63	571	Well	Example of the present invention
3-6	3-7	3	M	3	F6	e	28	566	Well	Example of the present invention	M	F7	e	27	502	Well	Example of the present invention
3-8	3-7	3	M	3	F8	e	48	609	Well	Example of the present invention	M	F7	e	27	502	Well	Example of the present invention
3-8	3-9	3	M	4	F8	e	48	609	Well	Example of the present invention	M	F9	f	72	624	Well	Example of the present invention
3-10	3-9	F10	f		48	620	Well	Example of the present invention				F9	f	72	624	Well	Example of the present invention
3-10	3-11	F10	f		48	620	Well	Example of the present invention	F11	f			25	585	Well	Comparative example
3-12	3-11	F12	f		19	538	The welding bead outward appearance is bad	Comparative example	F11	f			25	585	Well	Comparative example
3-12	3-13	F12	f		19	538	The welding bead outward appearance is bad	Comparative example	F13	f		29	596	Well	Example of the present invention
3-14	3-13	F14	f		28	666	Well	Example of the present invention	F13	f		29	596	Well	Example of the present invention

Table 19

Welding point No.	C	Si	Mn	Ti	N	Mo	Nb	Ni	B	B/N quality % ratio in the weld metal	Grain boundary ferrite growing amount in the weld metal (area %)	Remarks
Welding point No.	C	Si	Mn	Ti	N	Mo	Nb	Ni	B	B/N quality % ratio in the weld metal		Remarks	3-1	0.09	0.47	1.29	0.004	0.0022	-	0.004	-	0.0009	0.41	16.3	Comparative example
3-2	0.09	0.49	1.31	0.004	0.0022	-	0.003	-	0.0012	0.55	10.0	Example of the present invention	3-1	0.09	0.47	1.29	0.004	0.0022	-	0.004	-	0.0009	0.41	16.3	Comparative example
3-2	0.09	0.49	1.31	0.004	0.0022	-	0.003	-	0.0012	0.55	10.0	Example of the present invention	3-3	0.10	0.30	1.56	0.005	0.0023	-	0.004	-	0.0012	0.52	12.7	Example of the present invention
3-4	0.09	0.31	1.62	0.004	0.0031	-	0.004	-	0.0014	0.45	17.2	Comparative example	3-3	0.10	0.30	1.56	0.005	0.0023	-	0.004	-	0.0012	0.52	12.7	Example of the present invention
3-4	0.09	0.31	1.62	0.004	0.0031	-	0.004	-	0.0014	0.45	17.2	Comparative example	3-5	0.09	0.39	1.32	0.004	0.0031	0.28	0.019	-	0.0019	0.61	9.2	Example of the present invention
3-6	0.10	0.41	1.32	0.004	0.0033	0.48	0.003	-	-	-	14.5	Example of the present invention	3-5	0.09	0.39	1.32	0.004	0.0031	0.28	0.019	-	0.0019	0.61	9.2	Example of the present invention
3-6	0.10	0.41	1.32	0.004	0.0033	0.48	0.003	-	-	-	14.5	Example of the present invention	3-7	0.09	0.40	1.33	0.005	0.0029	-	0.004	-	0.0034	1.17	14.7	Example of the present invention
3-8	0.09	0.32	1.77	0.004	0.0030	0.19	0.018	-	0.0017	0.57	10.4	Example of the present invention	3-7	0.09	0.40	1.33	0.005	0.0029	-	0.004	-	0.0034	1.17	14.7	Example of the present invention
3-8	0.09	0.32	1.77	0.004	0.0030	0.19	0.018	-	0.0017	0.57	10.4	Example of the present invention	3-9	0.09	0.30	1.57	0.005	0.0029	0.20	0.011	-	0.0018	0.62	9.5	Example of the present invention
3-10	0.10	0.31	1.64	0.006	0.0035	0.18	0.012	-	0.0021	0.60	9.1	Example of the present invention	3-9	0.09	0.30	1.57	0.005	0.0029	0.20	0.011	-	0.0018	0.62	9.5	Example of the present invention
3-10	0.10	0.31	1.64	0.006	0.0035	0.18	0.012	-	0.0021	0.60	9.1	Example of the present invention	3-11	0.10	0.29	1.76	0.005	0.0046	0.17	0.011	-	0.0020	0.43	26.8	Comparative example
3-12	0.09	0.31	1.59	0.005	0.0042	-	0.006	-	0.0019	0.45	25.0	Comparative example	3-11	0.10	0.29	1.76	0.005	0.0046	0.17	0.011	-	0.0020	0.43	26.8	Comparative example
3-12	0.09	0.31	1.59	0.005	0.0042	-	0.006	-	0.0019	0.45	25.0	Comparative example	3-13	0.09	0.44	1.34	0.006	0.0026	0.49	0.005	-	-	-	13.4	Example of the present invention
3-14	0.10	0.43	1.30	0.005	0.0027	-	0.020	-	-	-	14.2	Example of the present invention	3-13	0.09	0.44	1.34	0.006	0.0026	0.49	0.005	-	-	-	13.4	Example of the present invention

Claims

1. used for submerged arc welding solder flux, it is characterized in that: contain 20～45% the atomized iron powder of N content below 0.0030 quality % with respect to the solder flux total amount, above-mentioned solder flux also contains 1 group or 2 groups that selects from A group and B group, wherein the A group: 0.2～2.0 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Mo conversion total in Mo powder, molybdenum-iron powder and the Mo compound powder; B group: 0.02～0.15 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Nb conversion total in Nb powder, ferro-niobium powder and the Nb compound powder.

2. the used for submerged arc welding solder flux of record in the claim 1 is characterized in that: above-mentioned solder flux also contains the convert B compound of 0.03～0.30 quality % that accounts for the solder flux total amount of useful B.

3. the used for submerged arc welding solder flux of claim 1 or 2 any one record, it is characterized in that: with respect to the solder flux total amount, % represents with quality, above-mentioned solder flux contains from SiO ₂: 10～28%, CaCO ₃: 5～15%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds.

4. the used for submerged arc welding solder flux of claim 1 or 2 any one record, it is characterized in that: above-mentioned solder flux also contains 1 group or 2 groups that selects from A group and B group, wherein the A group: 0.2～2.0 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Mo conversion total in Mo powder, molybdenum-iron powder and the Mo compound powder; The B group: 0.02～0.15 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Nb conversion total in Nb powder, ferro-niobium powder and the Nb compound powder, and also with respect to the solder flux total amount, % represents with quality, also contains from SiO ₂: 10～28%, CaCO ₃: 5～15%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds.

5. manufacture method with submerged-arc welding welding point of good weld metal zone toughness, it is characterized in that: in the manufacture method of the submerged-arc welding welding point by the large-line energy submerged-arc welding solder joints of weld heat input more than 150kJ/cm, adopt the solder flux welding of claim 1 record have Ti content below the 0.006 quality %, the steel formed of the mother metal of Nb content below 0.012 quality %.

6. the manufacture method of submerged-arc welding welding point of record in the claim 5 is characterized in that: above-mentioned solder flux is formed and is also contained the convert B compound of 0.03～0.30 quality % that accounts for the solder flux total amount of useful B.

7. the manufacture method of putting down in writing in the claim 5 or 6 of burying lonely weldering welding point, it is characterized in that: above-mentioned solder flux composition also contains 1 group or 2 groups that selects from A group and B group, wherein the A group: 0.2～2.0 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Mo conversion total in Mo powder, molybdenum-iron powder and the Mo compound; B group: 0.02～0.15 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Nb conversion total in Nb powder, ferro-niobium powder and the Nb compound.

8. the manufacture method of the submerged-arc welding welding point of claim 5 or 6 any one record, it is characterized in that: with respect to the solder flux total amount, % represents with quality, above-mentioned solder flux is formed and is also contained from SiO ₂: 10～28%, CaCO ₃: 5～15%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds.

9. the manufacture method of the submerged-arc welding welding point of claim item 5 or 6 any one record, it is characterized in that: above-mentioned solder flux composition also contains 1 group or 2 groups that selects from A group and B group, wherein the A group: 0.2～2.0 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Mo conversion total in the compound of Mo powder, molybdenum-iron powder and Mo; The B group: 0.02～0.15 quality % that accounts for the solder flux total amount more than a kind or 2 kinds with Nb conversion total in the compound of Nb powder, ferro-niobium powder and Nb, and also with respect to the solder flux total amount, % represents with quality, also contains from SiO ₂: 10～28%, CaCO ₃: 5～1 5%, MgO:15～38%, Al ₂O ₃: 3～20%, TiO ₂: 2～10%, CaF ₂: 2～10%, the metal powder beyond atomized iron powder, Mo powder, molybdenum-iron powder, Nb powder and the ferro-niobium powder: select in 2～8% more than a kind or 2 kinds.