JPH06277869A - Seamless tube steel wire for submerged arc welding - Google Patents

Abstract

PURPOSE:To produce a wire by which a satisfactory workability can be attained in a high speed welding, which is applied to a fillet welding, etc., of a built-up H shape steel sheet, etc. CONSTITUTION:A seamless tube steel wire for a submerged arc welding, whose outer diameter D is 3.2 to 6.4mm, and an inner diameter(d) is (0.3 to 0.7)XDmm, and contg. <=0.12% C and 0.5 to 2.7% Mn, is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire for submerged arc welding, which is applied to fillet welding of built-up H-shaped steel sheets and the like using SM400 and SM490 steels defined in JIS G3106, and more particularly to high speed downward or downward welding. The present invention relates to a seamless pipe steel wire for submerged arc welding capable of obtaining a stable bead shape in horizontal fillet welding.

[0002]

2. Description of the Related Art For fillet welding of a built-up H-shaped steel sheet for construction, a steel material is temporarily attached to an H-shape as shown in FIG.
The flanges 1 and 1'and the T-shaped portions of the web 2 are welded and joined from both sides. From the viewpoint of good welding efficiency, submerged arc welding is often used, but higher welding efficiency is required. ing.

In the submerged arc welding in this case, a pumice-like fusion type flux and a solid wire are used, and two electrodes are used for welding with a downward or horizontal fillet at a welding speed of usually about 1.5 m / min.

[0004]

A welding speed of 2 m is obtained by welding two electrodes using a pumice-like fusion type flux and a solid wire.
When performing downward or horizontal fillet welding at a speed of approx./min, downward welding may cause poor fit at the toe of the weld bead, undercut may occur, or horizontal welding may result in a convex bead or undercut. The current situation is that cuts have occurred and are not actually adopted.

The present inventors have made various studies in terms of welding flux composition and welding conditions in order to improve welding workability in high-speed welding at a welding speed of about 2 m / min, but no satisfactory results have been obtained. From these studies, it was speculated that it was necessary to softly widen the welding arc in order to improve the familiarity of the beads.

According to the present invention, the shape of the wire is examined in addition to the conventional welding conditions, and the welding speed is 2 m / m.
It is an object of the present invention to provide a wire having good bead familiarity and good welding workability even in high speed welding of about a minute.

[0007]

The present invention is a seamless pipe steel wire having a wire outer diameter D of 3.2.
~ 6.4mmφ, inner diameter d is (0.3-0.7) x Dmm
And, the wire C: 0.12% or less, Mn: 0.5 ~
The subject is a seamless pipe steel wire for submerged arc welding, which is characterized by containing 2.7%.

[0008]

The function of the present invention will be described in detail below.
First, the shape of the wire of the present invention is a pipe wire (hollow wire) as compared with general solid wire and flux-cored wire.
It is limited to. Comparing the case of using a pipe wire and a solid wire in two-electrode welding, the bead width becomes wider when the pipe wire is used as compared with the case where a solid wire that is normally used is used.

Although the reason for this is not clear, it is considered that the arc generation point at the time of welding is partial in the pipe wire as compared with the solid wire and it is fluctuating at a high speed. It is considered that the arc is soft and the bead width is widened without concentrating on the bead, which improves the familiarity of the bead. Further, the pipe wire of the present invention needs to have an inner diameter d of (0.3 to 0.7) × Dmm. That is, when the inner diameter d of the pipe wire is less than 0.3 × Dmm, there is no difference from the solid wire, the bead width does not widen, and the conformability is not sufficiently improved. On the other hand, the inner diameter d of the pipe wire is 0.7 ×
When the thickness exceeds D mm, the wall thickness becomes small, so that when used at a high current, the current density becomes excessive and the bead does not spread, and on the contrary, the alignment of the toes of the bead becomes unstable and a good bead cannot be obtained.

The outer diameter D of the pipe wire of the present invention is limited to 3.2 to 6.4 mmφ. The reason is that the wire diameter must be 3.2 mmφ or more to widen the arc and widen the bead width for use at high current, and if it is less than that, the effect cannot be sufficiently obtained. This is because when the outer diameter D of the wire exceeds 6.4 mmφ, a concave bead tends to be formed, which is not preferable.

Further, the pipe wire of the present invention needs to be a seamless pipe wire. The seamless pipe wire mentioned here has a shape as shown in FIG. 2 (a), and is distinguished from the fold wire shown in FIG. 2 (b) as an example. That is, the wire cross-section is not intended for the folding wire formed from the band steel, and the wire itself is easily twisted during welding,
Center deviation from the groove center is likely to occur, resulting in poor usability.
On the other hand, the present invention uses a seamless pipe wire whose cross section is nearly concentric and symmetrical in all directions, and is flexible, easy to handle, and less likely to twist.

The C content of the pipe wire of the present invention must be 0.12% or less. C amount is 0.1
If it exceeds 2%, C in the weld metal will depend on the steel plate used.
An excessive amount causes hot cracking. Further, the pipe wire of the present invention preferably has a C content as small as possible, but since 0.01% or more of steel strip is industrially supplied at present, the C content of the wire of the present invention is the lower limit. Value.

Further, the Mn content in the pipe steel wire of the present invention must be 0.5 to 2.7%. When the amount of Mn is less than 0.5%, a pock mark is generated on the bead surface.
On the other hand, if the Mn content exceeds 2.7%, the strength of the weld metal used becomes excessive and cold cracking occurs.

[0014]

EXAMPLES The effects of the present invention will be more specifically shown by the following examples. First, 16 types of wires W1 to W16 shown in Table 1 were produced. In Table 1, W1 to W6 are pipe steel wires of the example of the present invention, W7 to W13 are pipe steel wires of comparative examples, W14 is a hollow insert wire of comparative examples, and W15 and W16 are solid wires of comparative examples.

This wire was combined with a commercially available SiO ₂ —MnO-based pumice-like molten flux to perform a horizontal fillet welding test with a plate thickness of 16 mm. The steel plate is JIS G3106
The SM490B applicable product of No. 1 was assembled into a test piece having a length of 750 mm and provided for welding. The test body is horizontal as shown in FIG. 3A, and the electrodes 5 and 6 are θ ° with respect to the flange steel material 1.
Tilt (35 °). In addition, the wire is welded in the direction of the welding line with respect to the steel web, and the first pole wire 5 has θL ° (90 °)
The pole wire 6 was tilted at θT ° (70 °). The distance D between the electrodes is 20 mm.

Further, since a leg length of about 5 to 6 mm is generally required for a horizontal fillet having a plate thickness of about 16 mm, the welding conditions shown in Table 2 were used by adjusting for each wire type. In this case, the welding conditions are adjusted according to the wire diameter, and the welding speed is 1.7-
It was 2.0 m / min. The welding test results are shown in Table 3.

In Table 3, No. 1-No. No. 6 is an embodiment of the present invention. 7-No. 16 is a comparative example. As a result of these, No. 1 of the present invention. 1-No. No. 6 had good familiarity and good bead appearance. Of the comparative examples, No.
No. 7 was not preferable because the outer diameter D of the pipe steel wire was excessively large and the weld bead was a concave bead.

Of the comparative examples, No. No. 8 was not preferable because the outer diameter D of the pipe steel wire was too small and the weld bead width was narrow, resulting in a convex bead. In Comparative Example No. 9, the inner diameter d of the pipe steel wire was excessively large and the weld bead widths became uneven, resulting in a defect. Of the comparative examples, No. No. 10 was not preferable because the inner diameter d of the pipe steel wire was too small and the welding bead width was narrow, resulting in a convex bead.

Among the comparative examples, No. No. 11 was a pipe steel wire, but due to excessive C content of the wire, high temperature cracking occurred in the weld metal and it became defective. Of the comparative examples, No. No. 12 is a pipe steel wire, but since the Mn amount of the wire was too small, a pock mark was generated on the surface of the weld bead and it became defective. Of the comparative examples, No. Although 13 is a pipe steel wire, the strength of the weld metal was increased due to the excessive Mn content of the wire, resulting in defective root cracking.

Of the comparative examples, No. Although reference numeral 14 is a hollow wire, the wire was twisted due to a folded wire, and the wire was not straightened during welding, and the aiming position of the wire was misaligned to form a meandering bead, resulting in a poor appearance. Of the comparative examples, No. 1
5 and No. Since 16 was a solid wire, the bead did not spread and became a convex bead, which was not preferable.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

As described above, according to the present invention, in the downward or horizontal fillet submerged arc welding method of built-up H-section steel using SM steel, as shown in the embodiment, the welding workability is improved even in high-speed welding. Good welds with no weld cracks are obtained, which is of great industrial value.

[Brief description of drawings]

FIG. 1 is a schematic view of a beam member assembled in an H shape.

[Explanation of symbols]

 1, 1 ': Flange steel 2: Web steel

FIG. 2A is a schematic sectional view of a seamless pipe steel wire. (B): It is a cross-sectional schematic diagram of a folding pipe wire.

[Explanation of symbols]

 3, 3 ': Wire steel part 4, 4': Wire hollow part

FIG. 3A is a sectional view showing the positions of a welding test plate and a wire used in an example of the present invention. (B): It is a front view which shows arrangement | positioning of the wire used in the Example of this invention.

[Explanation of symbols]

1: Flange steel 2: Web steel 5: First pole wire 6: Second pole wire θ: Tilt of wire from flange steel (°) θL: Tilt of first pole wire from web steel in the welding line direction (°) θT: inclination of the welding line direction of the second pole wire from the web steel material (°) D: distance between electrodes (mm) W: welding direction

Claims (1)

[Claims] 1. A seamless pipe steel wire having a wire outer diameter D of 3.2 to 6.4 mmφ and an inner diameter d of (0.3
~ 0.7) x Dmm, and the wire contains C: 0.12% or less and Mn: 0.5 to 2.7%, a seamless pipe steel wire for submerged arc welding.