JPH0631482A - Metal flux wire for gas shield arc welding - Google Patents

Abstract

(57) [Summary] [Object] To provide a flux-cored wire for gas shielded arc welding, which can obtain a weld metal having excellent strength and toughness even in high heat input welding. [Constitution] 80% or more of a metal powder containing 0.2 to 3% of Mo is contained and 10 to 30% of a total weight of a flux having a C content of 0.3% or less is included.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-based flux-cored wire for gas shielded arc welding used for welding steel structures, which provides stable strength and toughness even when welded with high welding heat input. To be

[0002]

2. Description of the Related Art Gas shielded arc welding using metal-based flaked wires is increasing in terms of labor saving and improvement of production efficiency. The metal-based composite wire is composed mainly of metal powder consisting mainly of iron powder, with an arc stabilizing component and a small amount of slag forming agent added, and has a higher melting rate at the same welding current than solid wire of the same diameter, In addition, there is little generation of spatter. Therefore, it is widely used in the fields such as construction machinery and steel frame processing that require high welding speed. JP-A-63-183795, JP-A-63-2
Japanese Patent No. 15395 discloses a metal-based flux-cored wire that contains about 80% or more of metal powder and has a large amount of welding and little spatter, but there is no specific example regarding the mechanical properties of the weld metal. At present, little attention is paid. When the welding heat input is increased in order to obtain a high deposition rate, the cooling rate of the welded portion becomes small, and quenching becomes insufficient, which may result in deterioration of strength and deterioration of toughness. If, for example, the C content of the outer shell or the flux is increased to improve the hardenability and the C content of the weld metal is increased, hot cracking occurs or the CO reaction becomes violent and the low spattering characteristic of the cored wire is impaired. There was such a problem.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to improve the strength of a conventional metal-based flux-cored wire for gas shielded arc welding, which is often a problem when the welding heat input is increased to obtain a high deposition rate. Is to provide a metal-based flux-cored wire for gas shielded arc welding, which improves deterioration of toughness and deterioration of toughness.

[0004]

The present invention provides C: 0.05.
% (Wt%) or less of the mild steel outer shell containing 10 to 30% of flux containing 80% or more of metal powder containing Mo: 0.2 to 3% as a flux composition with respect to the total wire weight. It is a wire with metal flacks for gas shielded arc welding, which features C: 0.05%.
(Weight%) In a mild steel outer shell of 80% or more of a metal powder containing Mo: 0.2 to 3% as a flux composition, and a flux of C less than 0.3% in total wire weight. Is a metal-based flaked wire for gas shielded arc welding, characterized in that the flux composition is Mo in a mild steel outer shell of C: 0.05% (wt%) or less. : 80% or more and less than 90% of metal powder containing 0.2 to 3%, and C of less than 0.3%, based on the total wire weight, 1
It is a wire with metal flacks for gas shielded arc welding, characterized by containing 0 to 30%.

[0005]

Function: The outer skin is work hardened by being drawn with the flux and then drawn. Therefore, if a low alloy steel skin is used, an annealing step is necessary because the strength level of the wire becomes too high. The encapsulated flux may be sintered or deteriorated by the softening annealing heat treatment of the wire, and annealing is not preferable. Therefore, it is important to use a mild steel outer shell having a C content of 0.05% or less so that an annealing step is not required. Further, setting C to 0.05% or less is effective in reducing spatter and preventing hot cracking together with the amount of C in the flux described later. The outer skin is formed by molding a mild steel hoop as shown in a or b of FIG. 1 and the joint is left as it is, or the joint as shown in c is welded before or after filling the flux. A closed one can be used.

The flux contained in the steel outer shell is
It consists of metal powder (alloy component adjustment, deoxidizer), arc stabilizer, and slag forming agent. First, as the metal powder, it is necessary to contain 80% or more of the metal powder in the flux composition in order to achieve the high deposition rate, which is a characteristic of the metal-based flux-cored wire. In addition, it is necessary to secure sufficient hardenability and improve strength and toughness even at high welding heat input for obtaining a high deposition rate. Therefore, as a result of diligent examination of the additive alloying element and the addition amount, it was found that the addition of Mo has a remarkable effect on the improvement of the hardenability. The amount of addition is preferably 0.2 to 3% in the metal powder. If it is less than 0.2%, the amount of Mo in the weld metal is 0.02.
% Or less, the effect of Mo cannot be expected. Meanwhile, 3%
If added over the range, the amount of Mo in the weld metal increases,
The upper limit was set to 3% because it causes a marked increase in strength and deterioration in toughness. Mo can be added as an alloy powder, and the same effect can be obtained by adding it in the form of alloy iron powder by a water atomizing method.

The flux amount is 10 with respect to the total wire weight.
If it is less than%, it is not possible to expect an improvement in the amount of deposition due to the concentration of current on the outer skin, and the amounts of arc stabilizer and slag-forming agent are not sufficient and the amount of spatter increases. If added in excess of 30%, there is a risk of wire breakage due to the large amount of included flux during wire drawing, and the current is excessively concentrated in the outer cover during welding, and the outer cover is selectively melted, and the internal flux remains unmelted in the molten pool. Short circuit to increase the amount of spatter generated.

From the viewpoint of the amount of deposited metal, what is added as the metal powder is preferably 50% or more of iron powder, and is represented by Mn, Si, Al, Ti and their alloyed iron. And a deoxidizing agent and alloying elements such as Cu and Ni. Further, it is preferable to add an arc stabilizer containing at least one kind of K, Na and F in the range of 0.5 to 5%.

The arc stabilizer contributes to the reduction of spatter, but if it is less than 0.5%, its effect is not sufficient, and 5%.
If added over the range, the arc becomes unstable and the amount of spatter increases. Examples of arc stabilizers include potassium titanate, potassium titanium silicate, potassium silicofluoride, sodium silicate, lithium fluoride, sodium fluoride and the like.

The slag forming agent has an important function for protecting the weld bead and maintaining the shape of the weld bead. The addition amount is preferably at least 1% or more, but 20
If it exceeds%, the amount of slag is increased, and the effect of the high deposition amount, which is a characteristic of the metal flux-cored wire, cannot be expected so much. Examples of slag forming agents include TiO ₂ , S
iO ₂ , Al ₂ O ₃ , MnO, MgO, CaO, ZrO
_2, etc.

If the amount of metal powder is 80% or more of the amount of flux, a high deposition amount can be secured.
It is possible to further reduce the amount of spatter by limiting the addition amount to less than 10% and using the rest as an arc stabilizer and a slag forming agent. CO ₂ is preferable as a gas to be used when welding is performed using the metal flux-cored wire for gas shielded arc welding of the present invention, but when welding with less spatter is required, It is also possible to use Ar—CO ₂ , Ar—O ₂ or the like.

The effects of the present invention will be clarified by the following specific examples.

[0013]

EXAMPLE A hoop having a chemical composition shown in Table 1 (a plate thickness of 0.8 mm) was used as a steel shell, and a wire having a diameter of 1.2 mm in which a flux of the composition shown in Table 2 and a jacket were combined was used. The groove shape shown in FIG. 2 was used for the SM400 steel plate having a thickness of 20 mm, and the reverse polarity was 300 A-35 V-30 cm /
Min, shield gas: 100% CO ₂ , flow rate: 20 l /
Min, wire protrusion length: 20 mm, downward multilayer welding was performed. The results are shown in Table 3.

The test items include the amount of welding per unit time, the amount of spatter generated, and the full size at 0 ° C. of 2 mmV.
A notch Charpy impact test and a No. A2 round bar tensile test were performed. The amount of deposition is 120 g / min or more, and the amount of spatter is 3 g, referring to the amount of solid wire deposited under the same conditions.
It was judged to be good when it was less than or equal to / minute. Mechanical properties were evaluated as good when vE ≧ 100 J and tensile strength ≧ 490 MPa.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

No. 1 to No. No. 5 is within the range of the present invention, has sufficient strength and toughness, has a large amount of deposition, and has a small amount of sputtering. Further, when C in the flux is less than 0.3%, the total amount of metal powder in the flux is 90%.
% Of less than%. No. 1 to No. 3 It can be seen that the amount of sputtering is smaller than those of Nos. 4 and 5. No.
No. 6 was a case where 0.072% C was used for the outer skin, which was hardened during wire drawing and a wire break occurred, so intermediate annealing was performed at 650 ° C.
I went under the condition of time. Since the C content was high and the flux was altered by heat treatment, spatter was often generated during welding, and workability was deteriorated.

No. In No. 7, the Mo content is less than 0.2%, the hardenability is insufficient, and the strength and toughness are low. No. No. 8 exceeded the upper limit of the amount of Mo, the strength remarkably increased and the toughness deteriorated. No. 9 is the total amount of metal powder in the flux is 8
It is less than 0% and the amount of deposited metal is small. No. No. 10 had a flux weight of less than 10% with respect to the total wire weight, and generated a large amount of spatter and a small amount of welding. N
o. In No. 11, the flux weight exceeds 30%, and the amount of spatter is large.

[0020]

As specifically illustrated by the above examples, the present invention has sufficient hardenability even at high heat input, is excellent in strength and toughness, and has a large amount of welding as compared with a solid wire. Moreover, a metal flux-cored wire for gas shield arc welding with a small amount of spatter is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing sectional shapes of various types of flux-cored wires.

FIG. 2 is a sectional view of a groove shape of a test piece used in a welding evaluation test of a flux-cored wire.

[Explanation of symbols]

 1 Steel skin 2 Flux

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehisa Tabata 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Technical Research Headquarters (72) Inventor Hayaya Matsuyama Kawasaki-cho, Chuo-ku, Chiba No. 1 Kawasaki Steel Co., Ltd. Technical Research Division

Claims (3)

[Claims] 1. C: 0.05% (wt%) or less of a mild steel outer shell as a flux composition, Mo: 0.2-3%
A metal-based flux-cored wire for gas shield arc welding, characterized in that a flux containing 80% or more of metal powder containing is contained in an amount of 10 to 30% with respect to the total weight of the wire. 2. C: 0.05% (% by weight) or less of a mild steel outer shell having a flux composition of Mo: 0.2 to 3%.
80% or more of metal powder containing
Flux is less than 10 to 30 with respect to the total wire weight
% Metal-containing flux-cored wire for gas shielded arc welding. 3. C: 0.05% (% by weight) or less of a mild steel outer shell having a flux composition of Mo: 0.2 to 3%.
A metal system for gas shield arc welding, comprising 80% or more and less than 90% of a metal powder containing C, and further containing 10 to 30% of a flux having a C content of less than 0.3% with respect to the total wire weight. Flux-cored wire.