JP6029513B2 - Flux-cored wire for gas shielded arc welding - Google Patents

Description

  The present invention relates to a flux cored wire mainly used for welding steel structures such as shipbuilding and bridges, and more particularly to a highly efficient flux cored wire suitable for lateral welding.

Conventionally, gas shield arc welding using a flux-cored wire has been performed in various fields in order to perform the welding operation with high efficiency. For example, among the flux-cored wires that can efficiently perform fillet welding, a gas that can obtain good welding workability especially at the time of high-speed welding of a primer coated steel sheet and can obtain excellent pore resistance A flux-cored wire for shield welding is disclosed (for example, see Patent Document 1).
In fields such as shipbuilding and bridges, a primary rust preventive paint is often applied to the surface of a steel material used as a welding base material in order to prevent rusting during the manufacturing period. Patent Document 1 provides a flux-cored wire having high efficiency and good porosity resistance in fillet welding without peeling off the paint when welding using this primary anticorrosive agent coated steel sheet. .

JP 2000-42787 A

  At present, as a transverse welding wire, a titania-based all-position flux-cored wire (hereinafter, appropriately referred to as an all-position FCW) is widely used. When performing transverse welding using FCW for all positions, (1) If welding current is increased and welding speed is lowered with the aim of improving work efficiency, welding bead droops and the bead appearance and shape are impaired. (2) Slag amount Therefore, there is a problem that the slag peelability in the narrow groove is extremely poor, and the slag that cannot be completely peeled off is taken into the weld metal and induces a welding defect.

  Here, since the slag of the component system prescribed | regulated with the flux-cored wire of patent document 1 has melting | fusing point higher than a titania-type slag, it is thought that the problem (bead dripping, slag peeling difficulty, etc.) in transverse welding can be solved. . However, only the component system described in Patent Document 1 has room for poor fusion due to slag entrainment and improvement in the mechanical performance of the weld metal in the lateral welding.

In addition, in conventional flux-cored wires, when a slag forming agent exhibiting a high melting point is positively added, droplet transfer tends to be disturbed and the amount of spatter generated tends to increase, and the mechanical properties of the weld metal tend to deteriorate. .
Therefore, welding bead sag is suppressed without impairing welding workability such as reduction of spatter generation and arc stability required for flux-cored wires, and without impairing the mechanical properties of the weld metal, and Development of a flux-cored wire that can suppress welding defects such as slag entrainment is desired.

  The present invention has been made in view of such problems, and reduces spatter generation, suppresses weld bead droop without impairing arc stability and weld metal mechanical properties, and slag winding. It is an object of the present invention to provide a flux-cored wire for gas shielded arc welding that can suppress welding defects such as welding.

As a result of intensive studies, the present inventors have found the following matters.
In the flux-cored wire, the melting point of the slag is increased by changing the slag component system to a ZrO ₂ system rather than a TiO ₂ system. By increasing the melting point of the slag, the flux-cored wire can not only suppress dripping of the weld bead that occurs in the process of melting the molten metal even when the welding heat input is excessive, but can also improve the peelability. . Furthermore, compared with the conventional wire which suppressed the welding bead drooping by increasing the amount of slag, it becomes possible to reduce the amount of slag and extremely reduce welding defects such as slag entrainment.

However, the high melting point type slag component system has poor arc stability, resulting in an increase in the amount of spatter generated and deterioration in mechanical properties. Titania-based flux-cored wire has excellent arc stability and generates a small amount of spatter, resulting in good welding workability. This is because TiO ₂ which is the main component of slag has a function of stabilizing the arc.
If only TiO ₂ is added to the high melting point type slag component system, which is the main point of the present invention, for the purpose of stabilizing the arc, slag covering after welding is not possible due to the difference in melting point from ZrO ₂ which is the main component of slag. In particular, in horizontal welding, slag entrainment was induced, and the problem could not be solved.
Therefore, by adjusting the balance between TiO ₂ and Ti and ZrO ₂ among the components defined in the present invention, it was possible to develop a flux-cored wire taking advantage of both advantages.

A flux-cored wire for gas shielded arc welding according to the present invention (hereinafter, appropriately referred to as a flux-cored wire or simply a wire) is a flux-cored wire for gas shielded arc welding in which a flux is filled in a steel outer sheath,
Per total mass of wire,
TiO ₂ : 0.2 to 0.9% by mass,
Ti: 0.005 to 0.015 mass%,
C: 0.01-0.05 mass%,
Mn: 1.5 to 4.0% by mass,
Total of Zr conversion value of Zr compound and Zr oxide and metal Zr: 0.5 to 2.0% by mass,
Sum of Si conversion value of Si compound and Si oxide and metal Si: 0.5 to 2.0% by mass,
Total of B conversion value of B compound and B oxide and metal B: 0.002 to 0.010% by mass,
0.74 · [Ti] / ([TiO ₂ ] · [Zr]): 0.005 to 0.040 (where [Zr] is the sum of the Zr converted value of the Zr compound and the Zr oxide and the metal Zr) ,
[B] / [Mn]: 0.001 to 0.005 (where [B] is the sum of the B compound and the B value of the B compound and the metal B),
Der is, the balance being Fe and unavoidable impurities der Rukoto.

According to such a configuration, the flux-cored wire has a slag component system of ZrO ₂ that has a melting point higher than that of titania-based slag, so that the weld bead sag at a high current (or at a low welding speed). Is suppressed, and welding defects such as slag entrainment approach to zero as much as possible. Further, the flux-cored wire contains a predetermined amount of a predetermined component, and thus has effects such as arc stability, suppression of generation of fume and spatter, improvement of mechanical properties, and gloss of the bead surface.

  The flux-cored wire for gas shielded arc welding according to the present invention further includes an F-converted value of the F compound, an Na-converted value of the Na compound and Na oxide, and a K-converted value of the K compound and K oxide, based on the total mass of the wire. Is preferably 0.70% by mass or less.

  According to such a configuration, the flux-cored wire contains a predetermined amount of F, Na, and K, so that the arc is further stabilized without increasing the amount of spatter generated.

In the flux shielded wire for gas shielded arc welding according to the present invention, it is preferable that the total of either one or both of Nb and V is 0.040% by mass or less per the total mass of the wire.
According to such a configuration, the mechanical performance is not deteriorated in the weld metal of the weld joint.

In the flux-cored wire for gas shielded arc welding according to the present invention, the Mn is preferably 2.0 to 3.0% by mass.
According to such a configuration, the flux-cored wire is further improved in action as a deoxidizer by Mn.

The flux-cored wire for gas shielded arc welding according to the present invention preferably has a flux filling rate of 10 to 30% by mass.
According to such a configuration, the flux-cored wire is more likely to exert the flux effect.

The flux-cored wire for gas shielded arc welding according to the present invention is preferably used for lateral welding.
Flux-cored wire reduces spatter generation in lateral welding, suppresses weld bead sag, and suppresses weld defects such as slag entrainment without impairing arc stability and the mechanical properties of the weld metal. be able to.
The flux-filled ear of the present invention is particularly suitable for lateral welding, but is not limited to lateral welding, and can also be used for horizontal fillet welding, downward welding, and the like.

  According to the flux cored wire according to the present invention, it is possible to suppress welding bead sag and to suppress welding defects such as slag entrainment. Further, the amount of spatter generated can be reduced and the arc stability is not impaired. Furthermore, the mechanical properties of the weld metal are not impaired, and the crack resistance of the weld metal is improved.

Hereinafter, embodiments of the present invention will be described in detail.
≪Flux-cored wire≫
The flux cored wire of the present invention is formed by filling a steel outer shell with a flux. And, per the total mass of the wire, TiO ₂ , Ti, C, Mn, “total of Zr converted value of Zr compound and Zr oxide and metal Zr”, “Si converted value of Si compound and Si oxide and metal Si and , “Total of B conversion value of B compound and B oxide and metal B”, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])” (where [Zr] is Zr conversion value of Zr compound and Zr oxide and sum of metal Zr), “[B] / [Mn]” (where [B] is the sum of B conversion value of B compound and B oxide and metal B) ).

The flux-cored wire may further include a predetermined amount of the total of the F converted value of the F compound, the Na converted value of the Na compound and Na oxide, and the K converted value of the K compound and K oxide per the total mass of the wire. Good.
Further, in the flux-cored wire, it is preferable that the total of either one or both of Nb and V is suppressed to a predetermined amount or less per the total mass of the wire.

Here, Ti, Mn, B, Nb, and V are metals. That is, for example, Ti is metal Ti, and “metal Ti” means one or more of “pure metal Ti” and “alloy Ti”. The same applies to other elements. That is, the thing as a metal means that it is not an oxide and a compound.
“Oxide” means one or more of “single oxide” and “composite oxide”. “Single oxide” means, for example, an oxide of Zr alone (ZrO ₂ ) in the case of Zr, and “composite oxide” means a combination of a plurality of these single oxides, for example, It refers to both oxides containing a plurality of metal components such as Zr, Si, and B. The same applies to the “compound”.
The “Zr converted value of Zr compound and Zr oxide” is a value obtained by converting the sum of “Zr compound” and “Zr oxide” into “metal Zr”. The same applies to other elements.
Furthermore, [Ti], [TiO ₂ ], and [Mn] indicate the contents (mass%) of Ti, TiO ₂ , B, and Mn in the weld metal, respectively. [Zr] represents “the sum of the Zr converted value of the Zr compound and the Zr oxide and the metal Zr”, and [B] represents “the total of the B converted value of the B compound and the B oxide and the metal B”. Show.

Hereinafter, the reason for limiting the components of the wire will be described.
_<TiO 2: 0.2~0.9 mass%>
TiO ₂ can stabilize the arc and reduce the generation of fume and spatter. If the amount of TiO ₂ is less than 0.2% by mass, the effect of arc stabilization cannot be obtained, and the amount of generated fumes and the amount of generated spatters increase. On the other hand, if it exceeds 0.9 mass%, the solidification temperature of the slag is lowered, the slag envelope is non-uniform, and welding defects such as deterioration of peelability and slag entrainment are likely to occur. Therefore, TiO ₂ content is set to 0.2 to 0.9 mass%. The amount of TiO ₂ is preferably 0.7% by mass or less from the viewpoint of making the slag envelope more uniform.

<Ti: 0.005-0.040 mass%>
Ti has a function of stabilizing the arc, and most of it is retained in the weld metal, so that the droplet transfer is made smooth without making the slag covering uneven. When the amount of Ti is less than 0.005% by mass, the effect of arc stabilization is not clear. On the other hand, when it exceeds 0.040 mass%, a part of oxidized Ti moves to slag as TiO ₂ and the slag covering becomes non-uniform. Therefore, the Ti amount is 0.005 to 0.040 mass%. The amount of Ti is preferably 0.015% by mass or less from the viewpoint of making the slag envelope more uniform.

<C: 0.01-0.05 mass%>
C is oxidized to generate CO and CO ₂ gas, which is accompanied by explosion of droplets. There exists an aim which suppresses scattering of a spatter and a fume generation amount by making C amount into 0.05 mass% or less. C is an element necessary for obtaining good mechanical performance, and the lower limit is 0.01% by mass. Therefore, the C amount is 0.01 to 0.05 mass%.

<Mn: 1.5 to 4.0% by mass>
Mn acts as a deoxidizer to remove oxygen in the weld metal as slag and improve mechanical properties. If the amount of Mn is less than 1.5% by mass, its function is small. On the other hand, if it exceeds 4.0% by mass, the strength of the weld metal increases and the toughness decreases. Therefore, the amount of Mn is 1.5 to 4.0 mass%. The amount of Mn is preferably 2.0% by mass or more from the viewpoint of further improving mechanical properties, and is preferably 3.0% by mass or less from the viewpoint of improving toughness.

<Total of Zr conversion value of Zr compound and Zr oxide and metal Zr: 0.5 to 2.0% by mass>
Since ZrO ₂ is a main component of the high melting point slag, addition is essential. In order to obtain an effect that only suppresses weld bead sagging, the amount of Zr added to the wire, that is, the total of the Zr converted value of the Zr compound and the Zr oxide and the metal Zr (Zr total amount) is 0.5 mass. % Or more is necessary. However, since Zr in the weld metal deteriorates the mechanical properties, the upper limit is set to 2.0 mass%. Further, Zr, when added in the form of a metal or alloy, the ZrO ₂ is formed by reaction with oxygen in the weld metal by deoxidation, it has the same effect as ZrO _2. Zr oxides and Zr compounds also exhibit the same effects as ZrO ₂ . Therefore, the total amount of Zr is set to 0.5 to 2.0% by mass. The total amount of Zr is preferably 1.0% by mass or more from the viewpoint of further suppressing welding bead sagging, and is preferably 1.5% by mass or less from the viewpoint of improving mechanical properties.

<The total of Si conversion value of Si compound and Si oxide and metal Si: 0.5 to 2.0 mass%>
Like ZrO ₂ , SiO ₂ is the main component of the flux in the present invention, and it must be added because it acts as a slag forming agent. SiO ₂ is an effective component for obtaining a glossy bead appearance. If the Si amount, that is, the sum of the Si conversion value of the Si compound and Si oxide and the metal Si (Si total amount) is less than 0.5% by mass, the gloss of the bead surface cannot be obtained. On the other hand, when it exceeds 2.0 mass%, a nonuniformity will arise in a slag covering. Also, Si, when added in the form of a metal or alloy, SiO ₂ is formed by reaction with oxygen in the weld metal by deoxidation, it has the same effect as SiO _2. Si oxides and Si compounds exhibit the same effects as SiO ₂ . Therefore, the total amount of Si is 0.5 to 2.0 mass%. The total amount of Si is preferably 0.7% by mass or more from the viewpoint of exerting the effect of obtaining the gloss of the bead surface, and 1.0% by mass or less from the viewpoint of making the slag covering more uniform. It is preferable that

<Total of B conversion value of B compound and B oxide and metal B: 0.002 to 0.010 mass%>
B serves as a nucleus in the solidification process of the weld metal and serves to refine the structure. If the amount of B, that is, the total of B converted values of the B compound and B oxide and the metal B (B total amount) is less than 0.002% by mass, improvement in mechanical properties cannot be obtained. On the other hand, when it exceeds 0.010 mass%, various performances other than mechanical properties such as deterioration of hot cracking resistance tend to deteriorate. Therefore, the total amount of B is set to 0.002 to 0.010 mass%. The total amount of B is preferably 0.008% by mass or less from the viewpoint of improving various performances other than mechanical properties. In addition, even if B is an oxide form and a compound form, the same effect is exhibited.

<“0.74 · [Ti] / ([TiO ₂ ] · [Zr]) (where [Zr] is the total of the Zr-converted value of the Zr compound and the Zr oxide and the metal Zr)”: 0.005 0.040>
TiO ₂ and ZrO ₂ have a large difference in melting point, and greatly affect bead sag and slag peelability after welding. Although addition of Ti is indispensable for stabilizing the arc, excessive addition oxidizes Ti, disturbs the balance with ZrO _2, and makes the slag cover non-uniform. The Zr oxide and the Zr compound are the same as ZrO ₂ . Therefore, the relationship between the contents of [TiO ₂ ], [Zr], and [Ti] was defined as described above. If the value of the above relationship is less than 0.005, not only the arc stability cannot be obtained, but also the weld bead droops. On the other hand, if it exceeds 0.040, the slag covering becomes non-uniform, and not only fusion failure such as slag entrainment is likely to occur, but also the surface of the weld bead is uneven as the slag hardens quickly. Therefore, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])” is set to 0.005 to 0.040. “0.74 · [Ti] / ([TiO ₂ ] · [Zr])” is 0.008 or more from the viewpoint of further improving the stability of the arc and further improving the weld bead shape. Preferably there is. Moreover, it is preferable that it is 0.020 or less from a viewpoint which makes a slag covering more uniform, and a viewpoint which makes a weld bead shape more favorable.

<[B] / [Mn] (where [B] is the sum of the B compound and the B value of the B compound and the B oxide): 0.001 to 0.005>
In order to obtain good mechanical performance at the welding heat input (0.9 to 1.5 kJ / mm) of the transverse joint, the relationship between the amount of B in the weld metal and the amount of Mn serving as a deoxidizer is important. "[B] / [Mn]", that is, if the value of the relationship between the B-converted value of the B compound and B oxide and the metal B (the total amount of B) and Mn is less than 0.001, the nucleus of B The structure is not sufficiently refined by generation. On the other hand, when it exceeds 0.005, the deoxidation effect by Mn cannot be obtained. Therefore, “[B] / [Mn]” is set to 0.001 to 0.005. “[B] / [Mn]” is preferably 0.003 or less from the viewpoint of further exerting a deoxidation effect.

<Total of F converted value of F compound, Na converted value of Na compound and Na oxide, and K converted value of K compound and K oxide: 0.70% by mass or less>
F, Na, and K are components added as an arc stabilizer. When the total amount exceeds 0.70% by mass, the amount of spatter generated tends to increase. Therefore, when it contains these, the total amount of F, Na, and K shall be 0.70 mass% or less. The total amount of F, Na, and K is preferably 0.20% by mass or less from the viewpoint of further reducing the amount of spatter generated. In addition, about a lower limit, it may not be prescribed | regulated in particular, and may be 0 mass%, but when adding, in order to acquire the effect, it is preferable to set it as 0.10 mass% or more.

<Total of either Nb or V or both: 0.040 mass% or less>
Nb and V form NbC and VC in the weld metal and degrade the mechanical performance of the weld metal. Therefore, it is necessary to provide an upper limit in order to obtain good mechanical performance in the weld metal of the weld joint. When the sum of either one or both of Nb and V (total amount of Nb and V) exceeds 0.040% by mass, the mechanical performance of the weld metal deteriorates. Therefore, when these are contained, the total amount of Nb and V is 0.040% by mass or less. Since Nb and V are inevitably mixed, no lower limit value is set. The total amount of Nb and V is preferably 0.004% by mass or less from the viewpoint of further improving the mechanical performance.

<Flux filling ratio: 10 to 30% by mass>
The flux filling rate (the mass of the flux with respect to the total mass of the wire) is not particularly defined, but is preferably 10 to 30% by mass from the viewpoint of stability during production of the flux-cored wire.

<Balance: Fe and inevitable impurities>
The balance of the entire flux-cored wire is Fe and inevitable impurities. The amount of Fe can be 80-95 mass%.
<Fe: 80 to 95% by mass>
Fe has the effect of increasing the amount of deposited metal and increases the welding efficiency. Moreover, it mixes with other flux raw materials, improves the fluidity of the flux, and suppresses fluctuations in the flux filling rate. If Fe is less than 80% by mass, the above effect cannot be obtained. On the other hand, the upper limit may be an amount that can add the above-described various flux components, for example, 95% by mass. Therefore, the amount of Fe can be 80-95 mass%. As the Fe source, there are iron powder, Fe-based alloy and the like in the flux other than the steel outer shell.

In addition to the wire component described above, a small amount of Ca, Li, etc. as a fine-tuning agent such as deoxidation, and Cu, Co, N as a further hardener for the weld metal are contained in the flux as the wire component. You can also. These elements do not affect the object of the present invention. Further, the flux contains a trace amount of an alkali metal compound other than the above elements.
In addition to Nb and V described above as inevitable impurities, for example, Ni, Mo, Cr, etc., respectively, Ni: less than 0.1% by mass, Mo: less than 0.01% by mass, Cr: 0.30% by mass % May be contained. However, it is not limited to these components and numerical values.

<Others>
As a method of manufacturing a flux-cored wire, a method in which a flux is spread in the length direction of a steel strip and then formed into a circular cross-section so as to be wrapped, or a method in which a steel pipe having a large diameter is filled with a flux and drawn There is. However, since any method does not affect the present invention, any method may be used. In addition, there are seams with and without seams. Although it is not necessary to define anything about the components of the outer skin, it is common to use a material of mild steel or low alloy steel from the viewpoint of cost and wire drawing. Moreover, although copper plating may be given to the surface, the presence or absence of plating is not ask | required.

  Hereinafter, in order to explain the effects of the present invention, examples that fall within the scope of the present invention and comparative examples that fall outside the scope of the present invention will be compared and described.

Welding was performed under the conditions shown in Table 3 using flux-cored wires having the wire components shown in Tables 1 and 2. Table 4 shows an example of the hoop component (skin component). Of the wire components in Tables 1 and 2, those not satisfying the scope of the present invention are indicated by underlining the numerical values.
The amount of each component contained in the flux-cored wire is as follows. C is a combustion-infrared absorption method, Ti, Si, Zr, Mn, B, Nb, and V are ICP emission spectroscopic analysis methods, and Na and K are atoms. F was measured by a neutralization titration method using an absorption analysis method.

And the following evaluation was performed.
<Fusion failure (including slag winding)>
The fusion failure was evaluated by investigating the fusion failure (including slag winding) inside the weld metal by an X-ray transmission test (based on JIS Z 3104).
The number of occurrences of poor fusion (pieces / 500 mm ^L (length)) was 0, and one or more were considered unacceptable.

<Bead appearance>
The bead appearance was evaluated by sensuality.
“○” indicates that there is no bead sagging and the bead overlap is good, “△” indicates that the bead shape after welding is drooping, and “x” indicates that the bead sagging is significant and lateral welding cannot be performed. .

<Welding workability (arc stability and spatter generation amount)>
The welding workability was evaluated by sensuality during welding.
“○” indicates that the droplet transfer is smooth and the amount of spatter is small, “△” indicates that the arc is slightly unstable and the amount of spatter is large, and “Δ” indicates that the arc is unstable and the amount of spatter is large. No) was marked “x”.

<Mechanical properties>
About the mechanical property, based on JISZ3111, the test piece was produced from the weld metal, and it evaluated by implementing a tensile test and an impact test. Specifically, tensile strength and 0 ° C. absorbed energy (toughness) were measured.
The tensile test piece is type IA0 and the impact test piece is a V-notch test piece.
Judgment criteria are “を” for those having a tensile strength of 540 MPa or more and 640 MPa or less and an impact value of 80 J or more, “◯” for those having a tensile strength of 540 MPa or more and 640 MPa or less and an impact value of 47 J or more, and tensile strengths of 540 MPa or more and 640 MPa or less. Those having an impact value of 47 J or more were evaluated as “Δ”, and those not satisfying the above range (the range of “Δ”) were evaluated as “X”.

<Crack resistance>
The crack resistance was evaluated by conducting a butt weld cracking test (based on JIS 3155) using a hydraulic C-type high-speed jig. Specifically, the crack occurrence rate when welding was performed under the following welding conditions was evaluated.
(Welding conditions)
[Test steel plate] JIS G3106 SM400B, 25 mm ^t (thickness) × (150 + 150) mm ^w (width) × 500 mm ^L (length)
[Groove shape] 40 ° V groove, root gap 4mm
[Backing material] Ceramic type [Welding method] Semi-automatic welding
[Welding posture] downward
[Current-Voltage] 240A-28V
Crack generation rate = total crack length / (welding length−crater length) × 100
Those with a crack occurrence rate of 10% or less were accepted and those with a crack rate exceeding 10% were rejected.

(Comprehensive evaluation)
The number of occurrences of poor fusion was zero, the appearance of the beads, the welding workability was “◯”, the crack occurrence rate was 10% or less, and particularly excellent in mechanical properties was designated as “◎”.
The case where the number of fusion failures was zero, the bead appearance, the welding workability was “◯”, and the crack occurrence rate was 10% or less was designated as “◯”.
Among those other than the above, those having a crack occurrence rate of 10% or less were designated as “Δ”, and those having 10% or more were designated as “X”.
These results are shown in Table 5.

As shown in Table 5, no. Nos. 6 to 22 were satisfactory in each evaluation because they satisfy the scope of the present invention or for reference examples . In addition, No. 20 and no. For No. 21, “F + Na + K” was not added, and although welding workability was slightly inferior to those of the other examples and reference examples , performance without problems was obtained.
On the other hand, no. Since 1-5 and 23-31 do not satisfy the scope of the present invention, good results were not obtained.

No. 1 is a poor fusion because the total value of TiO ₂ , Mn and B exceeds the upper limit, and “0.74 · [Ti] / ([TiO ₂ ] · [Zr])” and the Si total value is less than the lower limit. In addition, the bead appearance, welding workability, mechanical properties, and crack resistance were poor.
No. 2 is because the total value of TiO ₂ , Mn, and B exceeds the upper limit, and “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, the Zr total value, and the Si total value are less than the lower limit. The fusion was poor, and the bead appearance, welding workability, mechanical properties, and crack resistance were poor.

No. 3, TiO ₂ , Mn exceeded the upper limit, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Si total value, B total value, “[B] / [Mn] ”Is less than the lower limit, resulting in poor fusion and inferior bead appearance, welding workability, and mechanical properties.
No. 4, TiO ₂ , Ti, Zr total value, B total value, “[B] / [Mn]”, “total value of F, Na, K” exceeds the upper limit value, C, “0.74 · [ Ti] / ([TiO ₂ ] · [Zr]) ”, Mn and Si total value was less than the lower limit, resulting in poor fusion and poor bead appearance, welding workability, mechanical properties, and crack resistance.
No. 5, TiO ₂ , Zr total value, B total value, “[B] / [Mn]”, “total value of F, Na, K” exceeds the upper limit, C, “0.74 · [Ti] / ([TiO ₂ ] · [Zr]) ”, Mn, and Si total value is less than the lower limit, resulting in poor fusion and inferior bead appearance, welding workability, mechanical properties, and crack resistance.

No. 23, TiO ₂ , Ti, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Si total value, “[B] / [Mn]” exceeds the upper limit value, C, Since Mn was less than the lower limit, the fusion was poor, and the bead appearance and mechanical properties were inferior.
No. 24, TiO ₂ , Ti, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Si total value, “total value of F, Na, K” exceeds the upper limit, Mn Was less than the lower limit, resulting in poor fusion and poor bead appearance, welding workability, and mechanical properties.
No. 25, TiO ₂ , Ti, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Si total value, “total value of F, Na, K” exceeds the upper limit, Mn , B total value was less than the lower limit, resulting in poor fusion and poor bead appearance, welding workability, and mechanical properties.

No. 26, TiO ₂ , Ti, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, the Si total value exceeds the upper limit, and the Mn and B total values are less than the lower limit. In addition, the bead appearance and mechanical properties were inferior.
No. 27 is fused because Ti, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Zr total value, Si total value exceeds the upper limit, and TiO ₂ and Mn are less than the lower limit. In addition, the bead appearance, welding workability, and mechanical properties were inferior.

No. 28, Ti, C, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Zr total value, Si total value, B total value, “[B] / [Mn]” Since the upper limit was exceeded and TiO ₂ and Mn were less than the lower limit, poor fusion occurred, and the bead appearance, welding workability, mechanical properties, and crack resistance were poor.
No. 29, Ti, C, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, “total value of Nb and V”, Zr total value, Si total value, B total value, “ [B] / [Mn] ”exceeded the upper limit and TiO ₂ and Mn were less than the lower limit, resulting in poor fusion and poor bead appearance, weldability, mechanical properties, and crack resistance.

No. 30 is Ti, C, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, “total value of Nb and V”, Zr total value, Si total value, B total value, “ [B] / [Mn] ”exceeded the upper limit and TiO ₂ and Mn were less than the lower limit, resulting in poor fusion and poor bead appearance, weldability, mechanical properties, and crack resistance.
No. 31 is Ti, “0.74 · [Ti] / ([TiO ₂ ] · [Zr])”, Mn, B total value, “[B] / [Mn]” is less than the lower limit, Poor welding workability and mechanical properties.

  In addition, No. The sample of 31 assumes the conventional flux cored wire described in Patent Document 1. As shown in this example, this conventional flux-cored wire does not satisfy a certain level in the above evaluation. Therefore, this example objectively revealed that the weld metal according to the present invention is superior to conventional flux-cored wires.

  The present invention has been described in detail with reference to the embodiments and examples. However, the gist of the present invention is not limited to the above-described contents, and the scope of right is widely interpreted based on the description of the claims. Must. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

Claims (6)

In the flux-cored wire for gas shield arc welding formed by filling the steel outer shell with flux,
Per total mass of wire,
TiO ₂ : 0.2 to 0.9% by mass,
Ti: 0.005 to 0.015 mass%,
C: 0.01-0.05 mass%,
Mn: 1.5 to 4.0% by mass,
Total of Zr conversion value of Zr compound and Zr oxide and metal Zr: 0.5 to 2.0% by mass,
Sum of Si conversion value of Si compound and Si oxide and metal Si: 0.5 to 2.0% by mass,
Total of B conversion value of B compound and B oxide and metal B: 0.002 to 0.010% by mass,
0.74 · [Ti] / ([TiO ₂ ] · [Zr]): 0.005 to 0.040 (where [Zr] is the sum of the Zr converted value of the Zr compound and the Zr oxide and the metal Zr) ,
[B] / [Mn]: 0.001 to 0.005 (where [B] is the sum of the B compound and the B value of the B compound and the metal B),
Der is, gas shielded arc welding flux cored wire the balance being Fe and unavoidable impurities der Rukoto.   Further, the total of the F converted value of the F compound, the Na converted value of the Na compound and the Na oxide, and the K converted value of the K compound and the K oxide is 0.70% by mass or less per total mass of the wire. The flux-cored wire for gas shielded arc welding according to claim 1.   Furthermore, the total of either one or both of Nb and V is 0.040 mass% or less per total mass of the wire, and contains the flux for gas shielded arc welding according to claim 1 or 2 Wire.   The flux cored wire for gas shielded arc welding according to any one of claims 1 to 3, wherein the Mn is 2.0 to 3.0 mass%.   The flux-filled wire for gas shielded arc welding according to any one of claims 1 to 4, wherein a filling rate of the flux is 10 to 30% by mass.   The flux-cored wire for gas shielded arc welding according to any one of claims 1 to 5, wherein the flux-cored wire is used for horizontal welding.