KR20220025957A - Steel wire for gas shielded arc welding, gas shielded arc welding method and manufacturing method of gas shielded arc welded joint - Google Patents

Abstract

A steel wire for gas shielded arc welding is provided. The present invention is a steel wire for welding comprising a steel sheath and a filler contained in the steel sheath, wherein the steel sheath is a steel having a sheath composition including REM: 0.005 to 0.20% in mass% with respect to the total mass of the steel sheath. It is a sheath, and the steel wire for gas shielded arc welding is a mass% with respect to the total mass of the total mass of the steel sheath and the total mass of the filler, C: 0.01 to 0.30%, Si: 0.10 to 5.00%, Mn: 0.5 to 5.0 %, P: 0.050% or less, S: 0.050% or less, REM: 0.004 to 0.18%, Cr: 3.0% or less, Ni: 3.0% or less, Mo: 0.02 to 1.5%, Cu: 3.0% or less, B: 0.0001 to It contains 0.005%, Ti: 0.02-0.40%, Al: 0.001-0.20%, Ca: 0.0008% or less, and has a composition whose balance consists of Fe and an unavoidable impurity.

Description

Steel wire for gas shielded arc welding, gas shielded arc welding method and manufacturing method of gas shielded arc welded joint

The present invention relates to a steel wire for gas shielded arc welding suitable for use in gas shielded arc welding, a gas shielded arc welding method, and a method of manufacturing a gas shielded arc welded joint. The present invention particularly relates to improving arc stability during arc welding, preventing scattering (sputtering) of molten metal, and improving bead shape.

BACKGROUND ART Gas shielded arc welding is widely used as a high-efficiency welding technique in industrial fields such as shipbuilding, architecture, bridges, automobiles, and construction machinery. Gas shielded arc welding is largely classified into MIG welding, MAG welding, and carbon dioxide gas welding according to the type of shielding gas. While gas shielded arc welding has an advantage of high efficiency, there is a problem that scattering (sputtering) of molten metal occurs in large quantities.

With respect to this problem, it is proposed to improve it by the following technique.

For example, patent document 1 describes the steel wire for carbon dioxide gas shielded arc welding. The steel wire described in Patent Document 1 is, in mass%, C: 0.20% or less, Si: 0.05 to 2.5%, Mn: 0.25 to 3.5%, rare earth element: 0.025 to 0.050%, P: 0.05% or less, S: 0.05 % or less, Ca: 0.0008% or less; Ti: 0.02 to 0.50%; Zr: 0.02 to 0.50%; It is a carbon dioxide gas shielded steel wire for arc welding which consists of a steel wire of a composition which consists of impurities.

In the steel wire described in Patent Document 1, if necessary, a predetermined amount of one selected from K, Cr, Ni, Mo, and V, or two or more types may be contained. According to the technique described in Patent Document 1, in positive carbon dioxide gas shielded arc welding, spray migration with excellent arc stability can be achieved, stable joint welding is possible, and a smooth bead shape can be achieved. is said to be obtainable.

Moreover, in patent document 2, the narrow improvement butt-welding method is described. The narrow line butt welding method described in Patent Document 2 is a narrow line butt welding method in which multilayer gas shield arc welding of a thick steel sheet is performed using a welding steel wire made of a steel wire containing 0.015 to 0.100 mass% of a rare earth element. . Gas shielded arc welding of the first layer uses the QL value defined as a function of welding current, welding voltage, welding speed, angle of improvement, and root gap as an index of the penetration shape of the first layer, and The QH value defined as a function of the welding voltage, the welding speed, the improvement angle, and the root gap is used as an index of the amount of weld metal, and the conditions are each satisfied within a predetermined range. According to the technique of patent document 2, also in the first layer of multilayer welding, it is excellent in the stability of an arc, and it is said that stable penetration is obtained.

Moreover, in patent document 3, the steel wire for welding used for gas-shielded arc welding is described. The steel wire for welding described in Patent Document 3 contains 2 to 60 mass % of REM, the balance being Fe and unavoidable impurities, the alloy steel powder is encased in a steel sheath, satisfies the range of 0.05-25.0 mass %, and the content rate of the said REM in the said welded steel wire satisfy|fills the range of 0.01-0.5 mass %. In addition, the content of each element obtained as a ratio to the mass of the welding wire by summing the mass of each element contained in the alloy steel powder and the mass of each element contained in the steel sheath is: C content: 0.01 to 0.30 mass%, Si content: 0.10-5.00 mass%, Mn content: 0.5 to 5.0 mass%, Cr content: 3.0 mass% or less, Ni content: 3.0 mass% or less, Mo content: 0.02 to 1.5 mass %, Cu content: 3.0 mass% or less, B content: 0.0001 to 0.005 mass%, Ti content: 0.02 to 0.20 mass%, Al content: 0.001 to 0.20 mass%, P content: 0.050 mass% or less, It is a steel wire for welding which satisfy|fills the range of content rate of S: 0.050 mass % or less, content rate of Ca: 0.0008 mass % or less, and the balance consists of Fe and an unavoidable impurity. According to the technique described in Patent Document 3, the yield of the welded steel wire is improved, the arc is stabilized, sputtering is reduced, and the bead shape is improved.

Moreover, in patent document 4, the flux containing wire for high yield strength and high toughness gas shielded arc welding is described. The flux-containing wire described in Patent Document 4 is a flux-containing wire in which the inside of the steel sheath is filled with flux. This flux-containing wire is a metal or alloy in the steel sheath and flux, as a total of mass% with respect to the total mass of the wire, C: 0.08 to 0.3%, Si: 0.2 to 2%, Mn: 0.5 to 2.5%, P : 0.02% or less, S: 0.02% or less, Al: 0.002 to 0.3%, Ti: 0.005 to 0.3%, Ni: 0.5 to 11%, Mg: 0.012 to 0.5%, carbon equivalent (Ceq.) 0.7 -2%, deoxidation element equivalent (Aleq.) 0.2-0.6%, Mo: 0.1-4%, W: 0.1-3%, Nb: 0.005-0.1%, V: 0.005-0.1%, Ta : contains one or two or more of 0.005 to 0.5%, the Nb equivalent (Nbeq.) is 0.05 to 0.5%, and the total content of the slag composition agent and the arc stabilizer contained in the flux is the total mass of the wire It is a flux-containing wire for high-yield strength, high-toughness gas-shielded arc welding, limited to 20% or less, the balance being Fe and unavoidable impurities, and the steel sheath being a seamless pipe. In the flux-containing wire described in Patent Document 4, an example in which one or two or more of Cu, Cr, Co, B, and one or two of Ca and REM is contained as a metal or an alloy in the flux. there is. According to the technique described in Patent Document 4, it is a wire for gas shielded arc welding used for MIG welding, MAG welding, etc. in high tensile strength steel sheet having a tensile strength of 950 MPa or more, and is a flux-containing wire with improved productivity compared to solid wire. .

Japanese Patent Publication No. 3945396 Japanese Laid-Open Patent Publication No. 2007-118068 Japanese Patent Publication No. 5794125 Japanese Laid-Open Patent Publication No. 2008-93715

The technique described in patent document 1 is a welding steel wire (solid wire) which consists of a steel wire containing REM in order to stabilize an arc. REM has a larger specific gravity than Fe, and is a strongly oxidizing metal, and has a high melting point of oxides. Therefore, it is easy to segregate in the solidification process of molten steel which is a manufacturing process of a raw material, and the REM content in a steel wire varies, and the part which becomes less than a specified value must be cut and removed. Moreover, in the steel wire containing REM, it becomes easy to generate|occur|produce a crack in the manufacturing process. From this point, in the technique described in patent document 1, there existed a problem that the yield of a steel wire fell and manufacturing cost rose.

Moreover, in the technique of patent document 2, narrow line butt welding of a thick steel plate is performed using the steel wire (solid wire) for welding which consists of a steel wire containing REM. However, there exists a problem similar to the technique described in patent document 1 in the steel wire for welding (solid wire) to be used.

Moreover, the technique described in patent document 3 is a steel wire which consists of a steel sheath and the alloy steel powder contained in the steel sheath, a so-called flux cored wire. In the steel wire described in Patent Document 3, since REM is contained in the alloy steel powder contained in the steel sheath, the problem based on the REM content in the solid wire described above is solved. However, since the alloy steel powder containing REM is easy to combine with oxygen, there is a problem that rust occurs in the alloy steel powder contained in the steel shell during storage. When a rusted steel wire is used for welding, porosity defects frequently occur inside the obtained weld metal, or weld metal toughness decreases, resulting in problems that desired weld joint integrity cannot be secured.

In addition, the technique described in Patent Document 4 is a steel wire (flux-containing wire) composed of a steel sheath and a flux contained in the steel sheath, and it is said that REM may be contained in the flux contained in the steel sheath. For this reason, also in the technique of patent document 4, there exists a risk that the same problem as the steel wire described in patent document 3 will arise.

The present invention solves the problems of the prior art, there is no quality change during storage such as rust generation, and has excellent arc stability during welding, can suppress the occurrence of sputter, and can improve the bead shape An object of the present invention is to provide a steel wire for gas shielded arc welding.

Another object of the present invention is to provide a gas shielded arc welding method and a method for manufacturing a gas shielded arc welded joint using this steel wire for gas shielded arc welding.

In order to achieve the above object, the present inventors paid attention to a flux-cored wire (hereinafter referred to as a steel wire for welding) comprising a steel sheath and a filler contained in the steel sheath. And the idea was made to contain the REM required for the stability improvement of an arc in a forced shell. By incorporating REM into the steel shell, there is no need to worry about quality changes during storage, such as rust generation, which occurs when REM is contained in the filler (flux of the filler).

In addition, in order to set it as a desired steel sheath, various processing and rolling processing are given to the steel plate used as a raw material. By this effect, compared to the case in which REM is contained in the solid wire, segregation of REM can be reduced to the extent that there is no problem, and it is recognized that a steel wire for welding containing a predetermined amount of REM can be stably manufactured did.

In addition, as gas shielded arc welding, from the viewpoint of performing MAG welding or carbon dioxide arc welding with positive polarity, by adding REM to the steel sheath, a stable cathode spot is formed on the surface of the wire near the volume. , the current path stabilizes. As a result, there is also an effect that a stable volume transfer is obtained.

On the other hand, as gas shielded arc welding, from the viewpoint of performing MIG welding, in reverse polarity MIG welding, there is a problem that the oxide on the surface of the steel sheet becomes a cathode spot and the arc becomes unstable easily. With respect to this subject, it was recognized that by adding REM to the steel shell, REM migrated in the molten pool, and a stable cathode spot was formed on the surface of the molten pool. As a result, the effect that the arc is stabilized is obtained.

The present invention has been completed by conducting further examination based on this recognition. The gist of the present invention is as follows.

(1) A steel wire for gas-shielded arc welding comprising a steel sheath and a filler contained in the steel sheath,

the steel shell is a steel shell having a shell composition containing REM: 0.005 to 0.20% in mass% with respect to the total mass of the steel shell;

The gas shielded arc welding steel wire is a mass % with respect to the total mass of the total mass of the steel sheath and the total mass of the filler,

C: 0.01 to 0.30%; Si: 0.10 to 5.00%,

Mn: 0.50 to 5.0%; P: 0.050% or less;

S: 0.050% or less; REM: 0.004 to 0.18%;

Cr: 3.0% or less; Ni: 3.0% or less;

Mo: 0.02 to 1.5%, Cu: 3.0% or less;

B: 0.0001 to 0.005%; Ti: 0.02 to 0.40%,

Al: 0.001 to 0.20%, Ca: 0.0008% or less

A steel wire for gas shielded arc welding, including, the balance being Fe and having a composition consisting of unavoidable impurities.

(2) The composition of the shell of the steel shell is, in mass% with respect to the total mass of the steel shell, C: 0.15% or less, Mn: 0.60% or less, P: 0.100% or less, S: 0.050% or less, Si : The steel wire for gas-shielded arc welding as described in (1) containing 3.0% or less.

(3) The steel wire for gas shielded arc welding according to (1) or (2), wherein the steel sheath is a welded pipe or a seamless pipe.

(4) The steel wire for gas shielded arc welding in any one of (1)-(3) whose total mass of the said filler is 20% or less with respect to the total mass of the said steel wire for gas shielded arc welding.

(5) A gas shielded arc welding method in which gas shielded arc welding is performed in a positive polarity using the steel wire for gas shielded arc welding according to any one of (1) to (4).

(6) The gas shielded arc welding method which performs gas shielded arc welding by MIG welding of reverse polarity using the steel wire for gas shielded arc welding in any one of (1)-(4).

(7) A method for manufacturing a gas shielded arc welded joint using the gas shielded arc welding method according to (5) or (6).

ADVANTAGE OF THE INVENTION According to this invention, there is no quality change during storage, such as rust generation|occurrence|production as a welding material, and it is excellent in the stability of an arc at the time of welding, and can suppress generation|occurrence|production of sputtering. Moreover, by stabilizing an arc, the gas shielded arc welding which was excellent also in a weld bead shape becomes possible. For this reason, a special effect is brought about industrially.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows schematically the cross section of the steel wire for welding of this invention.
Fig. 2 is an explanatory diagram schematically showing the outline of overlap fillet welding performed in the embodiment of the present invention.
3 is an explanatory view schematically showing an example of the gas shielded arc welding method of the present invention.

(Form for implementing the invention)

The steel wire for gas shielded arc welding of this invention is suitable as a steel wire for gas shielded arc welding for 490 MPa class - 780 MPa class high tensile strength steel sheets. The steel wire 1 for gas-shielded arc welding of this invention consists of the steel sheath 2 and the filler 3 contained in the said steel sheath 2, as shown in FIG. In the present invention, the REM contributing to the stability of the arc is contained in the steel shell.

The steel sheath 2 contains, in mass% relative to the total mass of the steel sheath, REM: 0.005 to 0.2%, and preferably further C: 0.15% or less, Mn: 0.60% or less, P: 0.100% or less, It has a shell composition including S: 0.050% or less and Si: 3.0% or less. First, the reason for limiting the skin composition will be described. In addition, unless otherwise indicated, "%" indicating the shell composition means "mass %".

REM: 0.005 to 0.20%

REM (rare earth element) is a generic term for elements containing atomic numbers 57 to 71 (lanthanoids) and Sc and Y. In the present invention, REM is an essential element for realizing the spray migration of droplets when MAG welding or carbon dioxide arc welding is performed in a positive polarity. Moreover, in MIG welding, REM has the effect|action which stabilizes an arc and suppresses the meandering of a bead. Such an effect becomes remarkable when REM: 0.005% or more contains. On the other hand, when the REM content exceeds 0.2%, the shading (deviation) of the REM in the volume is promoted, the arc becomes unstable, and the desired effect cannot be obtained. For this reason, the REM content contained in the steel shell was limited to the range of 0.005 to 0.20%. Moreover, Preferably it is 0.015 to 0.10 %. More preferably, it is 0.030 % or more and 0.060 % or less.

The above-described REM content represents the total content of each element contained in REM. In the present invention, each element contained in the above-described REM may be contained alone or in combination. Moreover, in REM, it is preferable to set it as La and Ce.

The steel sheath 2 contains, in mass%, REM: 0.005 to 0.20%, preferably further C: 0.15% or less, Mn: 0.60% or less, P: 0.100% or less, S: 0.050% or less, Si: It has a shell composition containing 3.0% or less. It is preferable that the steel sheath used in the present invention has a component equivalent to SPCC specified in JIS Z 3141 as an alloy component, except for containing the above-described REM. When the alloy element is contained in an excessive amount exceeding the SPCC equivalent component, cracks are likely to occur during solvent solidification or wire drawing of the steel shell material.

For this reason, the C content contained in the steel shell is preferably 0.15% or less. From the viewpoint of the mechanical properties of the weld metal, the C content is more preferably 0.10% or less, and still more preferably 0.08% or less. 0.01 % or more is preferable and, as for C content, 0.02 % or more is more preferable.

The Mn content contained in the steel shell is preferably 0.60% or less. From the viewpoint of manufacturability, the Mn content is more preferably 0.55% or less, and still more preferably 0.50% or less. 0.20 % or more is preferable and, as for Mn content, 0.25 % or more is more preferable.

The P content contained in the steel shell is preferably 0.100% or less. From the viewpoint of manufacturability, the P content is more preferably 0.050% or less, and still more preferably 0.010% or less. 0.002 % or more is preferable and, as for P content, 0.005 % or more is more preferable.

The S content contained in the steel shell is preferably 0.050% or less. From the viewpoint of manufacturability, the S content is more preferably 0.050% or less, and still more preferably 0.010% or less. 0.002 % or more is preferable and, as for S content, 0.005 % or more is more preferable.

The content of Si contained in the steel shell is preferably 3.0% or less. From the viewpoint of the workability of the shell, the Si content is more preferably 2.0% or less, and still more preferably 1.5% or less. 0.5 % or more is preferable and, as for Si content, 1.0 % or more is more preferable.

The steel wire 1 for gas shielded arc welding of this invention consists of the steel sheath 2 of the sheath composition containing said REM, and the filler 3 enclosed in the said steel sheath. In the steel wire 1 for gas shielded arc welding of the present invention, various alloying elements, fluxes, etc. necessary for forming a weld metal having characteristics such as predetermined strength and toughness are blended as the filler 3 . In addition, the various alloying elements mix|blended with the filler 3 may be good also as individual powder of various alloying elements, or an alloy of various alloying elements and Fe (For example, Ferro, such as Fe-Mn, Fe-Si, You may mix|blend as metal powders, such as alloy steel powder containing alloy (ferroalloy) powder and various alloy elements in complex. In addition, a filler may be made into metal powder, such as alloy element powder and alloy steel powder, or may use a metal powder and a flux together. In addition, by blending the flux, the arc is stabilized and the effect of reducing sputtering is further improved.

As what is contained in _a flux, TiO2, SiO2 _, MgO, CaO, CaF2 etc. which have an effect|action which maintains _a weld bead shape favorably can be illustrated, for example. These can be suitably selected, combined, and mix|blended as needed. In addition, from the viewpoint of welding workability, it is preferable to blend a rutile-based flux mainly composed of TiO ₂ , SiO ₂ , etc., and a basic flux containing MgO, CaF ₂ , CaO or the like as a main component from the viewpoint of weld metal toughness. Do.

It is preferable to limit the total mass of a filler to 20% or less with respect to the steel wire total mass. When the filler is blended in a large amount exceeding 20%, disconnection occurs during the production of the flux-cored wire, and the wire production becomes remarkably difficult.

In the steel wire for gas-shielded arc welding (steel wire for welding) of the present invention, the total mass of the mass of each element contained in the steel sheath and the mass of each element contained in the filler is calculated as each contained in the steel wire for welding. It is set as the content rate of an element, and it prescribes|regulates as mass % with respect to the total amount (total mass) of the steel wire for welding. That is, the content rate (mass %) of each element of the steel wire for gas shielded arc welding is defined by the following formula.

Content rate (mass %) of each element = [{(mass of each element contained in the steel sheath) + (mass of each element contained in the filler)}/(total mass of steel wire for welding)] x 100

The steel wire for welding of the present invention, in mass%, C: 0.01 to 0.30%, Si: 0.10 to 5.00%, Mn: 0.50 to 5.0%, P: 0.050% or less, S: 0.050% or less, REM: 0.004 to 0.18%, Cr: 3.0% or less, Ni: 3.0% or less, Mo: 0.02 to 1.5%, Cu: 3.0% or less, B: 0.0001 to 0.005%, Ti: 0.02 to 0.40%, Al: 0.001 to 0.20%, Ca : It contains 0.0008% or less, and has a composition (steel wire composition for welding) which balance consists of Fe and unavoidable impurities. In addition, the mass of a filler is a ratio with respect to the total amount (total mass) of the steel wire for welding as mentioned above, and it is preferable from a viewpoint of wire manufacture to set it as 10 to 20%.

Hereinafter, the reason for limitation of the composition of the steel wire for welding is demonstrated. In addition, unless otherwise indicated, "%" indicating the composition of the steel wire for welding means "mass %".

C: 0.01 to 0.30%

C is an element that effectively contributes to securing the strength of the weld metal. This effect becomes remarkable by containing 0.01% or more of C. On the other hand, in the case of gas-shielded arc welding, the C content exceeding 0.30% destabilizes the droplets and reduces the toughness of the weld metal. Moreover, containing of C exceeding 0.30 % becomes easy to disconnect at the time of manufacture of the steel wire for welding. From this point, content of C of the steel wire for welding was limited to 0.01 to 0.30%. Moreover, Preferably it is 0.01 to 0.08 %. More preferably, it is 0.01 % or more and 0.06 % or less. More preferably, it is 0.02 % or more and 0.05 % or less.

Si: 0.10-5.00%

Si has a deoxidation effect and is an element indispensable for deoxidation of molten metal, and this effect becomes remarkable when Si contains 0.10% or more of Si. When the Si content is less than 0.10%, the molten metal is not sufficiently deoxidized during gas shield arc welding, so that a blow defect occurs in the weld metal. Moreover, the electrical resistance of the steel wire for welding becomes low, and melting efficiency falls. On the other hand, the content of Si exceeding 5.00% increases the amount of slag produced by oxidation, and also saturates the amount of Si contributing to deoxidation in the molten metal. Moreover, the hardness of the steel wire for welding increases and workability falls. From this point of view, the Si content was limited to 0.10 to 5.00%. Moreover, Preferably it is 0.50 to 1.50 %. More preferably, it is 0.60 % or more and 1.40 % or less. More preferably, it is 0.80 % or more and 1.30 % or less.

Mn: 0.50 to 5.0%

Mn, like Si, has a deoxidation action and is an element essential for deoxidation of molten metal. Mn has an action of securing the toughness and strength of the weld metal. This effect becomes remarkable by containing 0.50% or more of Mn. If the content of Mn is less than 0.50%, the electrical resistance of the steel wire for welding becomes low, and the melting efficiency decreases. On the other hand, the content of Mn exceeding 5.0% increases the amount of slag generated by oxidation and saturates the amount of Mn contributing to deoxidation in the molten metal. Moreover, the hardness of the steel wire for welding increases and workability falls. From this point of view, the Mn content was limited to 0.50 to 5.0%. Moreover, Preferably it is 1.0 to 3.0 %. More preferably, it is 1.5 % or more and 2.5 % or less. More preferably, it is 1.8 % or more and 2.2 % or less.

P: 0.050% or less

P is an element having an action of lowering the melting point of the steel wire for welding and increasing the electrical resistance to increase the exothermic property, and contributes to the improvement of welding work efficiency. In addition, P has the action of stabilizing the arc with positive welding. This effect becomes remarkable by containing 0.010% or more of P. On the other hand, when the content of P exceeds 0.050%, the viscosity of the molten metal decreases, the arc becomes unstable, and small-grain sputtering occurs in a large amount, and high-temperature cracking is likely to occur in the weld metal. For this reason, the content of P was limited to 0.050% or less. Moreover, Preferably it is 0.010 to 0.050 %. More preferably, it is 0.015 % or more and 0.045 % or less. More preferably, it is 0.020 % or more and 0.040 % or less.

S: 0.050% or less

S decreases the viscosity of the molten metal and helps the volume to be suspended from the tip of the welding steel wire during welding, and has an action of stabilizing the arc in positive welding. Such an effect becomes remarkable when the content of S is 0.010% or more. On the other hand, when S content exceeds 0.050%, the viscosity of molten metal falls too much at the time of welding, and small-grain sputtering generate|occur|produces abundantly. Moreover, the toughness of a weld metal falls. For this reason, the content of S was limited to 0.050% or less. Moreover, Preferably it is 0.010 to 0.050 %. More preferably, it is 0.015 % or more and 0.045 % or less. More preferably, it is 0.020 % or more and 0.040 % or less.

REM: 0.004 to 0.18%

REM is contained in the steel sheath and not in the filler material. REM has the action of realizing spray migration of droplets when performing MAG welding or carbon dioxide arc welding in a positive polarity, and stabilizing the arc to suppress bead meandering when performing MIG welding. This effect becomes remarkable by containing 0.004% or more of REM. On the other hand, if the REM content exceeds 0.18%, the shading (deviation) of REM in the volume is promoted, the arc becomes unstable, and the desired effect cannot be obtained. For this reason, the content of REM was limited to the range of 0.004 to 0.18%. Moreover, Preferably it is 0.010 % or more and 0.10 % or less. More preferably, it is 0.050 % or more and 0.08 % or less.

In addition, "mischmetal" shown in Table 2, etc., is a mixture of rare earth elements obtained by reducing rare earth ore, and contains 40 to 50% of cerium (Ce), 20 to 40% of lanthanum (La), and 20 to 40% of neodium ( Nd) is 15% or less, and is a generic term for alloy additives composed of several percent.

Cr: 3.0% or less

Cr is an element having an action of increasing the strength of the weld metal and further improving weather resistance. In order to obtain such an effect, it is preferable to contain 0.3% or more of Cr. On the other hand, containing more than 3.0 % of Cr causes the fall of weld metal toughness. For this reason, content of Cr was limited to 3.0 % or less. Moreover, Preferably it is 0.3 to 3.0 %, More preferably, it is 0.5 to 1.0 %. More preferably, it is 0.7 % or more and 0.8 % or less.

Ni: 3.0% or less

Ni is an element having the action of increasing the strength of the weld metal and further enhancing the weather resistance. In order to acquire such an effect, it is preferable to contain 0.3% or more of Ni. On the other hand, Ni content exceeding 3.0% causes a decrease in weld metal toughness. For this reason, content of Ni was limited to 3.0 % or less. Moreover, Preferably it is 0.3 to 3.0 %, More preferably, it is 0.5 to 1.0 %. More preferably, it is 0.6 % or more and 0.9 % or less. Moreover, more preferably, it is 0.7 % or more and 0.8 % or less.

Mo: 0.02 to 1.5%

Mo is an element having an action of increasing the strength of the weld metal, and in order to obtain such an effect, it is required to contain 0.02% or more of Mo. On the other hand, when Mo exceeds 1.5 %, the toughness of a weld metal falls remarkably. For this reason, content of Mo was limited to 0.02 to 1.5% of range. Moreover, Preferably it is 0.2-1.0 %. More preferably, it is 0.3 % or more and 0.9 % or less. More preferably, it is 0.4 % or more and 0.8 % or less.

Cu: 3.0% or less

Cu is an element having the action of increasing the strength of the weld metal and further enhancing the weather resistance. In order to obtain such an effect, it is preferable to contain 0.2% or more of Cu. On the other hand, when Cu exceeds 3.0%, the toughness of a weld metal falls remarkably. For this reason, content of Cu was limited to 3.0 % or less. Moreover, Preferably it is 0.2 to 3.0 %, More preferably, it is 0.2 to 1.0 %. More preferably, it is 0.4 % or more and 0.8 % or less.

B: 0.0001 to 0.005%

B is an element having an action of increasing the strength of the weld metal, and in order to obtain such an effect, B content of 0.0001% or more is required. On the other hand, when the B content exceeds 0.005%, the toughness of the weld metal remarkably decreases. For this reason, the content of B was limited to the range of 0.0001 to 0.005%. Moreover, Preferably it is 0.0005 to 0.004 %. More preferably, it is 0.001 % or more and 0.003 % or less. More preferably, it is 0.002 % or more and 0.003 % or less.

Ti: 0.02 to 0.40%

Ti is an element contributing to an increase in the strength of the weld metal while acting as a deoxidizer. In order to obtain such an effect, it is required to contain 0.02% or more of Ti. If the content of Ti is less than 0.02%, deoxidation of the molten metal becomes insufficient, so that the viscosity decreases and the bead shape decreases. On the other hand, when Ti exceeds 0.40%, the toughness of a weld metal falls. For this reason, the content of Ti was limited to 0.02 to 0.40%. Moreover, Preferably it is 0.10 to 0.30 %. More preferably, it is 0.15 % or more and 0.20 % or less.

Al: 0.001 to 0.20%

Al is an element contributing to an increase in the strength of the weld metal while acting as a deoxidizer. In order to obtain such an effect, it is required to contain 0.001% or more of Al. If the content of Al is less than 0.001%, the deoxidation of the molten metal becomes insufficient, so that the viscosity decreases and the bead shape decreases. On the other hand, when Al exceeds 0.20%, the toughness of a weld metal falls. For this reason, the content of Al was limited to the range of 0.001 to 0.20%. Moreover, Preferably it is 0.10 to 0.15 %. More preferably, it is 0.12 % or more and 0.15 % or less.

Ca: 0.0008% or less

Ca is an element having an action of stabilizing the arc in positive welding. Such an effect becomes remarkable by containing 0.0002% or more of Ca. On the other hand, when Ca exceeding 0.0008% is contained, the stability of the arc is impaired. For this reason, the content of Ca was limited to 0.0008% or less. Moreover, Preferably it is 0.0002 to 0.0008 %. More preferably, it is 0.0002 % or more and 0.0006 % or less. More preferably, it is 0.0002 % or more and 0.0004 % or less.

The steel wire composition for welding consists of Fe and an unavoidable impurity remainder other than the above-mentioned component.

In addition, said composition (steel wire composition for welding) contains a steel sheath, the metal powder and flux contained as a filler.

In this invention, it is preferable that the steel sheath of the steel wire for welding is a welded pipe or a seamless steel pipe (seamless pipe). Thereby, moisture absorption of the steel wire for welding can be prevented and the fall of weldability can be suppressed.

It is preferable that the outer diameter of the steel shell be 3.0 to 6.0 mmφ.

Next, the preferable manufacturing method of the steel wire for gas shielded arc welding of this invention is demonstrated.

First, the manufacturing method of the steel wire for gas shielded arc welding in the case of using a welded pipe as a steel sheath is demonstrated.

Molten steel having the above-described shell composition is melted by a commercially available melting method such as a vacuum melting furnace to obtain a slab (steel ingot) having a predetermined shape. Next, the slab (steel ingot) is heated to obtain a hot rolled steel sheet by hot rolling, and then cold rolling including softening annealing is performed to obtain a cold rolled steel strip (plate thickness: about 1 mm or less). From this cold-rolled steel strip, a steel strip of a predetermined width is extract|collected, and it is set as a steel outer material. Next, it is preferable to give a cold bending process etc. to the obtained steel sheath raw material (steel strip), process it into a pipe shape, perform seam welding, and set it as a steel sheath (welded pipe). In addition, instead of seam welding, it is good also as a pipe shape by caulking.

Then, after filling the obtained welded pipe with a filler so that the composition of the above-described steel wire for welding may be satisfy|filled, it wire-draws by cold and sets it as the steel wire for welding of a desired outer diameter. It is preferable to apply|coat lubricating oil to the obtained steel wire for welding.

Then, the manufacturing method of the steel wire for gas-shielded arc welding in the case of using a seamless pipe as a steel sheath is demonstrated.

The steel sheath of the present invention does not have any problem even if it is a seamless steel pipe (seamless pipe) having a desired outer diameter. The manufacturing method of the steel wire for welding in the case of using a seamless steel pipe for a steel sheath is as follows.

Molten steel having a shell composition in the above-described predetermined range is melted by a commercially available melting method such as a vacuum melting furnace to obtain a round slab (or steel ingot) having a predetermined shape. Alternatively, the steel ingot may be heated and hot-rolled to obtain a round steel piece having a predetermined shape. Next, it is preferable to heat the obtained round slab or round steel slab to make a hollow raw material (seamless steel pipe) by perforation rolling, and to set it as a steel sheath (seamless pipe).

Thereafter, a filler is charged to the obtained seamless pipe so as to satisfy the composition of the steel wire for welding described above, and cold wire drawing or cold drawing including annealing is performed to obtain a welding steel wire having a desired outer diameter. desirable. It is preferable to apply|coat lubricating oil to the obtained steel wire for welding.

Next, the gas shielded arc welding method of this invention is demonstrated.

The present invention is a gas shielded arc welding method in which gas shielded arc welding is performed with positive polarity or reverse polarity using the above-described steel wire for welding.

As gas-shielded arc welding suitable for using the above-mentioned steel wire for welding, carbon dioxide gas arc welding, MIG welding, and MAG welding are mentioned, for example.

For example, as shown in FIG. 3, the steel plate 4 of 2 sheets is mutually overlapped, and overlap fillet welding is performed by gas shield arc welding. The welding steel wire 1 passed through the center of the welding torch 5 and continuously supplied from the welding torch 5 to the steel plate 4 is an anode and the steel plate 4 is a cathode, and the welding voltage from the welding power source is An arc is formed between the steel wire 1 for welding and the steel plate 4 by being applied and a part of shielding gas supplied from the inside of the welding torch 5 ionizing and plasma-izing. In the shielding gas, the portion flowing from the welding torch 5 to the steel sheet 4 without generating ion is removed from the outside air from the arc and a molten pool (not shown) formed by melting the steel sheet 4 . has a blocking role. The heat of the arc melts the tip of the steel wire 1 for welding into a volume, and the volume is transported to the molten area by electromagnetic force, gravity, or the like. When this phenomenon arises continuously with the movement of the welding torch 5 or the steel plate 4, the molten pool solidifies behind a welding line, and the welding bead 6 is formed. Thereby, bonding of the steel plate 4 of 2 sheets which faced is achieved.

In addition, a steel plate, welding conditions, etc. are suitably set according to the characteristic requested|required with respect to a weld joint.

As a gas shielded arc welding method, when performing positive polarity carbon dioxide gas arc welding and positive polarity MAG welding, it is preferable to set it as the following welding conditions.

<Conditions of carbon dioxide arc welding>

・Shield gas: 100% by volume CO ₂

・Shield gas flow rate: 20 L/min

・Welding current: 240-380A

・Welding voltage: 28-38V

・Welding speed: 30-80 cm/min

・Welding power: Inverter power

·Polarity: positive polarity

<MAG welding conditions>

Shielding gas: 80 vol% Ar + 20 vol% CO ₂

・Shield gas flow rate: 20 L/min

・Welding current: 240-380A

・Welding voltage: 28-38V

・Welding speed: 30-80 cm/min

・Welding power: Inverter power

·Polarity: positive polarity

As a gas shielded arc welding method, when performing MIG welding of reverse polarity, it is preferable to set it as the following welding conditions.

<MIG welding conditions>

・Shield gas: 100% by volume Ar

・Shield gas flow rate: 20 L/min

・Welding current: 100-280A

・Welding voltage: 16~24V

・Welding speed: 30-80 cm/min

・Welding power: Inverter power

·Polarity: reverse polarity

According to the gas shielded arc welding method of this invention, even if it performs carbon dioxide gas arc welding and MAG welding of positive polarity, since an arc is stabilized, sputter|spatter generation amount can be suppressed. Moreover, since an arc is stabilized even if overlap fillet welding is performed by MIG welding, the fluctuation|variation of a bead width can be suppressed.

Next, the gas-shielded arc welded joint of this invention is demonstrated.

The present invention is a method for manufacturing a gas shielded arc welded joint using the gas shielded arc welding method described above.

Here, as a gas shielded arc welding method, the case where carbon dioxide gas arc welding, MIG welding, and MAG welding are performed is demonstrated, for example. For example, as shown in FIG. 2 , in the method for manufacturing a gas shielded arc welded joint of the present invention, at least two or more steel sheets are butted, and multilayer welding is performed under specific welding conditions using the above-described steel wire for welding, A weld bead is formed to obtain a gas shielded arc weld joint. In addition, since a steel plate, welding conditions, etc. are the same as that of the above description, description is abbreviate|omitted.

As described above, according to the present invention, since there is no quality change during storage such as rust generation in the steel wire for welding, sputtering can be suppressed during carbon dioxide gas arc welding and MAG welding, and accordingly, arc An effect excellent in stability can be obtained.

Here, "excellent in arc stability" refers to a small amount of sputtering. Specifically, the sputtering amount measured by the method described in Examples to be described later indicates that the amount of sputtering is 1.5 g or less per 100 g of the deposition amount.

Moreover, in the case of MIG welding, since a stable cathode spot is formed on the surface of a molten pool and an arc is stabilized, gas-shielded arc welding excellent also in a weld bead shape can be implement|achieved.

Here, "excellent in the shape of a weld bead" means that the shape of the bead was observed from the surface of the bead over the entire length of the weld bead with an optical camera, and the maximum and minimum values of the bead width were obtained. From the obtained value, the difference between the maximum value and the minimum value of a bead width is computed, and it points out that the difference is 2.0 mm or less.

Hereinafter, based on an Example, this invention is further demonstrated.

Example

Molten steel of the shell composition shown in Table 1 was melted in a vacuum melting furnace, and it was set as the steel ingot (100 kg). The obtained steel ingot was hot-rolled and then cold-rolled to set it as the cold-rolled steel strip of plate|board thickness:0.8mm and width:16mm. These cold-rolled steel strips were used as a steel shell material, and cold bending was performed in the width direction to form a pipe shape, and then seam welded to obtain a steel shell (outer diameter: 3.0 mmφ). In addition, in the steel sheath obtained by seam welding, "W (welded pipe)" was shown in the column of the steel sheath shape of Table 2.

In addition, a part of the steel ingot is heated and made into a round steel piece having a predetermined shape by hot rolling, and then this round cast piece is heated and a hollow material (seamless steel pipe) is obtained by punch rolling, and a steel sheath (outer diameter: 3.0) mmφ). In addition, in the steel shell which consists of a seamless pipe, "S (seamless pipe)" was shown in the column of the steel shell shape of Table 2.

The filler was mix|blended with the obtained steel sheath, so that it might become the steel wire composition for welding of the content shown in Table 2, it cold-wired, and it was set as the steel wire for welding (diameter: 1.2 mmphi).

[Table 1]

[Table 2]

A welding test was performed using the obtained steel wire for welding, and the sputtering amount was investigated and the bead shape was investigated. The test method is as follows.

(1) Investigation of sputtering amount

Using the steel wire for welding of the composition shown in Table 2 (composition of the steel wire for welding), the bead-on welding was performed on a steel plate having a plate thickness of 12 mm under the welding conditions shown in Tables 3-1 and 3-2 for 1 min. (1 minute) was carried out. At this time, the welding current for carbon dioxide gas arc welding and MAG welding was 240 to 380 A, the welding voltage was 28 to 38 V, and the welding speed was selected to be in the range of 30 to 80 cm/min (cm/min). Among the sputters that occurred, sputters with a diameter of 0.1 mm or more were collected by a collection jig made of Cu previously installed around the welding jig. When the collected sputter is 0.8 g or less per 100 g of deposition, mark as “good”, sign: ◎, and when the amount of sputtering exceeds 0.8 g and less than 1.5 g per 100 g of deposition, set as “possible”, and sign: ○, per 100 g of deposition More than 1.5 g was set as "impossible", preference: (triangle|delta) was given, respectively, and it evaluated.

(2) Investigation of bead shape

As shown in Fig. 2, a steel sheet having a thickness of 25 mm is butted, using a welding steel wire having a composition shown in Table 2, and multilayer welding is performed under the welding conditions shown in Tables 4-1 and 4-2 (welding length: 250). mm) was performed. At this time, the welding current of MIG welding was 100-280A, the welding voltage was 16-24V, and the numerical value within the range of 30-80 cm/min (cm/min) of welding speed was selected, respectively. Over the entire length of the weld bead, from the bead surface, the shape of the bead was observed with an optical camera, and the maximum value and the minimum value of the bead width were calculated|required. From the obtained value, the difference between the maximum value and the minimum value of bead width was computed, and it was set as the bead shape parameter|index of the said steel wire for welding. When the difference between the maximum value and the minimum value of the bead width is 1.0 mm or less, “Good”, symbol: ◎, more than 1.0 mm and less than 2.0 mm as “possible”, symbol: ○, and more than 2.0 mm as “not” and a symbol: △ was assigned to each and evaluated.

The obtained result is shown in Table 5.

[Table 3-1]

[Table 3-2]

[Table 4-1]

[Table 4-2]

[Table 5]

In all of the examples of the present invention, even when positive carbon dioxide arc welding and MAG welding were performed, the arc was stable, and the amount of sputtering was small at 1.5 g or less per 100 g of the deposition amount. Moreover, even if it overlapped fillet welding by MIG welding, the fluctuation|variation of the bead width|variety was small, 2.0 mm or less.

1: Steel wire for welding
2: Forced integument
3: Filling material
4: steel plate
5: Welding Torch
6: welding bead

Claims (7)

A steel wire for gas-shielded arc welding comprising a steel sheath and a filler contained in the steel sheath, the steel wire comprising:
the steel shell is a steel shell having a shell composition containing REM: 0.005 to 0.20% in mass% with respect to the total mass of the steel shell;
The gas shielded arc welding steel wire is a mass % with respect to the total mass of the total mass of the steel sheath and the total mass of the filler,
C: 0.01 to 0.30%;
Si: 0.10 to 5.00%,
Mn: 0.50 to 5.0%;
P: 0.050% or less;
S: 0.050% or less;
REM: 0.004 to 0.18%;
Cr: 3.0% or less;
Ni: 3.0% or less;
Mo: 0.02 to 1.5%,
Cu: 3.0% or less;
B: 0.0001 to 0.005%;
Ti: 0.02 to 0.40%,
Al: 0.001 to 0.20%,
Ca: 0.0008% or less
A steel wire for gas shielded arc welding, including, the balance being Fe and having a composition consisting of unavoidable impurities. According to claim 1,
The shell composition of the steel shell is, in mass%, relative to the total mass of the steel shell, further C: 0.15% or less, Mn: 0.60% or less, P: 0.100% or less, S: 0.050% or less, Si: 3.0% A steel wire for gas shielded arc welding, comprising: 3. The method of claim 1 or 2,
The steel wire for gas shielded arc welding, wherein the steel sheath is a welded pipe or a seamless pipe. 4. The method according to any one of claims 1 to 3,
The total mass of the said filler is 20 % or less with respect to the total mass of the said steel wire for gas shielded arc welding, The steel wire for gas shielded arc welding. The gas shielded arc welding method which performs gas shielded arc welding in a positive polarity using the steel wire for gas shielded arc welding in any one of Claims 1-4. The gas shielded arc welding method which performs gas shielded arc welding by MIG welding of reverse polarity using the steel wire for gas shielded arc welding in any one of Claims 1-4. A method for manufacturing a gas shielded arc welded joint using the gas shielded arc welding method according to claim 5 or 6 .

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