KR20010058341A - Flux cored wire for electro gas arc welding - Google Patents

Abstract

PURPOSE: A wire for charging flux for the electro gas arc welding is provided in which the welding metal has high toughness and strength even when a welding part improved cross-sectional area exceeds 400 mm2 by optimally controlling constituents of flux consisting of the wire for electro gas welding. CONSTITUTION: In a wire for electro gas arc welding in which flux is charged, the flux charged wire is characterized in that the flux comprises 0.2 to 0.5 wt.% of non-metallic raw materials, 2.0 to 3.1 wt.% of Ca+Si+Mn, 0.15 to 0.5 wt.% of one or both of Ti and Mg, 0.002 to 0.005 wt.% of B and a balance of Fe powder, wherein the flux further comprises 1 wt.% or less of one or both of Ni and Mo.

Description

Flux cored wire for electro gas arc welding

The present invention relates to a flux filling wire for electrogas arc welding, and more particularly, to a flux filling for electrogas arc welding, which can stably secure excellent toughness of the weld metal even when the welded area of the weld is improved to 400 to 600 mm 2. It is about a wire.

Electrogas arc welding is generally widely used for welding for shipbuilding, steel structures, and large tank structures. Since the electrogas arc welding method performs welding under an atmospheric gas, the welding speed is generally high, so that the welding efficiency can be improved, the generation of weld defects can be effectively controlled, and thin plate welding can be facilitated. . However, in the case of welding by the above-described method, there is a problem that high heat input is caused in the welded portion, so that the weld metal crystal grains are superposed and a welded portion with high toughness cannot be obtained.

As an example of the technique for solving such a conventional problem, Japanese Patent Laid-Open No. 61-259894 is mentioned. According to the Japanese Laid-Open Patent, in the flux-filled electrogas arc welding wire, the composition of the flux is at least 0.5 to 2.2% of nonmetallic material, Zr 0.05 to 0.25%, Mn 1 to 3%, and Ti by weight% of the wire. It is characterized by the fact that one or two or more of the group consisting of Si, Mg is controlled at 0.2 to 0.8%.

However, the above-described flux filling wire for electro-gas welding can obtain a weld metal having excellent toughness in the case of a relatively small welded cross section (for example, 400 mm 2 or less). There is a practical problem that can not be limited to use for welding large structures, such as.

Accordingly, an object of the present invention is to provide a flux-filled wire for electric gas arc welding, in which a weld metal can have high toughness and strength even when a welded area having a cross-sectional area of more than 400 mm 2 is improved. do.

1 a, b are cross-sectional schematic diagrams of flux filled wire used in an embodiment of the present invention;

2 is an explanatory view showing a weld improvement cross-sectional area of a weld base material used in the embodiment of the present invention.

In the present invention for achieving the above object, in the flux-filled electrogas arc welding wire, the flux is a non-metallic material: 0.2 ~ 0.5%, Ca + Si + Mn: 2.0 ~ by weight% relative to the wire A flux filling wire comprising 3.1%, Ti, Mg, at least one sum: 0.15-0.5%, B: 0.002-0.005% and residual iron powder is provided.

Hereinafter, the present invention will be described.

In the electrogas arc welding method, the present inventors have conducted numerous studies and experiments to develop a flux-filled wire that exhibits excellent mechanical properties even when the welded section having an area of more than 400 mm 2 is improved. As a result, the present invention has been devised. In other words, the present inventors have studied how to improve the toughness of the weld metal through the relationship between the oxygen content, the nitrogen content, the hydrogen content and the nonmetal flux composition in the weld metal, and the influence of invasive inclusions and metal structures present in the trace metal in the weld metal. From these results, the optimum flux composition can be derived.

Hereinafter, the reason for limiting the specific compositional components of the flux constituting the flux filling wire for electrogas arc welding of the present invention will be described.

Non-metallic raw materials are added for the purpose of good weld bead appearance by slag formation and weld arc stabilization. Such non-metallic raw materials may be used by appropriately mixing oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , and fluorides such as CaF ₂ and NaF, but are not particularly limited thereto. However, if the amount of the non-metallic material is small, the slag formation is small to obtain a good bead appearance, and if the amount is too excessive, it is easy to cause the problem that the toughness of the weld metal is lowered by promoting the formation of impurity inclusions of the weld metal. Therefore, in the present invention, it is preferable to limit the content of the nonmetal raw material to 0.2 to 0.5% by weight of the wire.

Ca, Si, and Mn are added as deoxidizers, and it is preferable to limit the total addition amount by weight of the wire to 2.0 to 3.1%. If the total content is less than 2.0%, the effect of reducing the amount of oxygen in the weld metal is small, so that the welded part having the required toughness and strength cannot be obtained. If the content exceeds 3.1%, the weld metal not only decreases the toughness. This is because high temperature cracking is likely to occur.

Ti and Mg are strong deoxidizers and denitrifiers and are added to remove oxygen or nitrogen in the weld metal. In the present invention, it is required to add at least one of them, and preferably the amount of the addition is limited to 0.15 to 0.5% by weight of the wire. This is because if the added amount is less than 0.15%, the effect of improving toughness due to deoxidation and denitrification of the weld metal is small, and if it exceeds 0.5%, excessive slag formation impairs the arc stability.

B is added for the purpose of promoting the microstructure of the weld metal to improve the toughness of the weld metal and is a very important element in the present invention. In the present invention, the amount of B added is preferably limited to 0.002% to 0.004% by weight of the wire, which is less than 0.002% of the structure micronizing effect, and exceeds 0.004% to yield point and tensile strength of the weld metal. It is because it becomes a factor which narrows the gap of intensity | strength, and is not preferable.

As described above, the wire of the present invention filled with the flux whose component is controlled can be effectively used even in the case where the weld improvement cross section is wide, thereby obtaining a weld metal having excellent toughness.

Further, in the present invention, by adding Ni and Mo to the flux configured as described above, it is possible to ensure better toughness of the weld metal.

Ni acts to accredit the weld metal structure, and has the effect of stably maintaining toughness. However, if the amount is excessive, the strength may increase and the toughness may be impaired. In addition, Mo serves to prevent tissue deterioration at a high temperature of the weld metal, and also serves to improve the strength of the weld metal. However, if the added amount is excessive, the strength may increase, leading to a decrease in toughness.

Therefore, in the present invention, in terms of preventing high temperature cracking and securing toughness of the weld metal, more preferably, at least one of Ni and Mo is added, and the amount thereof is limited to less than 1% by weight of the wire.

Hereinafter, the present invention will be described in detail through examples.

(Example 1)

As shown in Table 1 below, the flux for the electrogas arc welding having different compositions was prepared. And as shown in Figure 1a, by filling each of the flux prepared as described above in the outer shell to prepare a welding wire having a wire diameter of 1.6mm. Next, the SM490 welding base material having a thickness of 35 mm as shown in FIG. 2 was welded using the wires prepared above. At this time, the welding conditions are as shown in Table 2 below. As shown in Table 2 below, the welding conditions were considered such that the welded section cross-sectional area was 600 mm 2.

division Foot honor Comparative Example Wire number One 2 3 4 5 6 One 2 3 4 5 6 7 8 Flux composition (% by weight) Nonmetallic Raw Materials CaF ₂ - 0.2 0.2 0.1 - 0.15 0.2 - 0.2 - 0.2 0.1 - 0.2 NaF 0.2 0.05 0.05 0.05 0.05 0.1 0.05 0.1 0.05 0.1 0.05 0.1 0.05 0.1 SiO ₂ 0.2 - 0.1 - 0.2 0.1 0.1 0.2 - 0.1 - 0.1 0.05 - Al ₂ O ₃ 0.05 0.1 - - 0.05 - - - 0.2 0.2 0.2 - 0.05 0.5 TiO ₂ 0.05 - 0.1 0.05 - - 0.1 0.1 - 0.1 - - - - Sum 0.5 0.35 0.45 0.2 0.3 0.35 0.45 0.4 0.45 0.5 0.45 0.3 0.15 0.8 Ca 0.15 0.2 0.2 0.1 0.2 0.1 0.15 0.1 0.15 0.1 0.1 0.3 0.2 0.25 Si 0.35 0.4 0.4 0.2 0.4 0.2 0.35 0.5 0.35 0.5 0.2 0.8 0.2 0.35 Mn 2.05 1.85 1.9 2.0 2.1 2.0 2.25 2.4 2.25 2.1 1.6 2.5 2.2 2.15 Ca + Si + Mn 2.55 2.4 2.5 2.3 2.7 2.3 2.75 3.0 2.75 2.7 1.9 3.6 2.6 2.75 Ti 0.1 - 0.2 0.3 0.1 0.2 0.1 - 0.1 0.4 0.1 0.2 0.2 0.3 Mg 0.1 0.2 0.2 0.2 0.1 0.1 0.1 0.2 - 0.2 0.1 0.2 0.1 - Ti + Mg 0.2 0.2 0.4 0.5 0.2 0.3 0.2 0.2 0.1 0.6 0.2 0.4 0.3 0.3 Ni - - - - 0.7 0.5 - - - - - - - - Mo - - - - - 0.2 - - - - - - - - Ni + Mo - - - - 0.7 0.7 - - - - - - - - B 0.002 0.003 0.004 0.002 0.002 0.004 0.001 0.01 0.003 0.002 0.003 0.003 0.004 0.003 Fe powder 16.7 17.0 16.6 17.0 16.1 16.3 16.6 16.4 16.7 16.2 17.4 15.7 16.9 16.1

Base steel grade Base material thickness (mm) Angle of improvement Back side Gap (mm) Welding current (A) Welding voltage (V) Improved cross-sectional area (mm2) Protective gas flow rate (ℓ / min) SM490 35 20 ° (2θ) V 11 420 40 600 35 (CO ₂ )

After welding the wires under the above welding conditions, weldability and tensile properties and impact toughness of the weld metal shown in FIG. 2 were measured and shown in Table 3 below. In addition, the results of the overall evaluation of the measured characteristics are shown in Table 3 below.

division Invention Comparison Wire no. One 2 3 4 5 6 One 2 3 4 5 6 7 8 Weldability Bead Appearance ○ ○ ○ ○ ○ ○ ○ △ ○ △ ○ ○ X △ Slag Peeling ○ ○ ○ ○ ○ ○ ○ ○ △ ○ ○ ○ X △ Spatter ○ ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ △ △ Tensile Properties Yield Point (N / ㎡) 462 480 455 476 495 486 441 490 425 480 405 540 486 485 Tensile Strength (N / ㎡) 540 564 535 543 562 564 510 580 502 590 480 625 564 546 Elongation (%) 26 26 27 26 25 25 26 24 27 23 29 21 26 27 Shock Absorption Energy (J) vE 0 108 103 105 107 164 165 61 56 45 38 42 34 132 48 vE-20 85 79 81 84 131 124 45 38 28 22 25 61 106 32 Comprehensive Evaluation ○ ○ ○ ○ ◎ ◎ △ △ △ X △ △ △ X

However, in the table, ◎ is very good, ○ is excellent, Δ is usually, and X is poor.

As can be seen in Table 3, when welding by the electrogas arc welding method using the present invention (1-4), it can be seen that not only weldability and tensile properties but also impact toughness. In addition, it is understood that the invention materials 5 and 6 have more excellent impact toughness than the invention materials (1 to 4) when one or more of Ni and Mo are added in the range of 1% or less.

On the contrary, in the case of electrogas arc welding using comparative materials 1 and 2 in which the content of B is out of the scope of the present invention, although the tensile property is good, the impact toughness is deteriorated, so that the weld wire is wide when the improved weld cross section is wide. It can be seen that it is not appropriate.

In addition, the comparative materials 3 and 4 distinguished from the present invention in terms of the amount of Ti and Mg added are poor in impact toughness, and the comparative materials 5 and 6 distinguished from the present invention in the total content of Ca + Si + Mn. Even in the case of the overall impact toughness is deteriorated, it can be seen that it is not suitable as a welding material in the case where the weld improvement cross section is large.

In addition, in the case of welding using comparative materials 7 and 8, which are distinguished from the present invention, in terms of non-metallic raw material content, it can be seen that, although the tensile properties and the impact toughness are good, the slag peeling property is poor and a healthy welding bead cannot be obtained. .

On the other hand, as shown in Figure 1b, the welding flux of Table 1 is filled in the outer shell to produce a welding wire having a wire diameter of 1.6mm, and even if the welding is performed under the conditions described above using the above Table 3 and Similar results were obtained.

As described above, according to the present invention, by controlling the components of the flux constituting the electrogas arc welding wire optimally, the flux filling wire for electric gas arc welding, which exhibits high toughness and strength even in a large area where the welded section having a cross section exceeding 400 mm 2. Its useful effect in the manufacture of fish.

Claims (2)

In the electric gas arc welding wire filled with flux, the flux is 0.2% to 0.5% by weight of the wire, and Ca + Si + Mn is 2.0 to 3.1% and the sum of one or more of Ti and Mg. Flux filling wire, characterized in that it comprises 0.15 to 0.5%, B: 0.002 to 0.005% and residual iron powder The flux charging wire according to claim 1, wherein the flux is further comprised of 1% or more of Ni and Mo within 1%.