JP3197407B2 - Flux-cored wire for gas shielded arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux-cored wire for gas shielded arc welding, which has a particularly good welding workability and is used for construction of various welded structures such as ships, steel frames, bridges and the like.

[0002]

2. Description of the Related Art Generally, a flux-cored wire for gas-shielded arc welding (hereinafter referred to as a flux-cored wire) is a slag forming agent, a deoxidizing agent, an alloying agent, an arc stabilizer, and an iron powder inside a mild steel or low alloy steel outer shell. And a flux composed of various raw materials such as The flux-cored wire has a more stable arc and less spatter than solid wire, and can be easily welded in various welding positions such as downward, horizontal, vertical, and upward, and provides a good bead. . Further, the flux-cored wire has a higher welding speed under the same current welding conditions. Flux-cored wires having such advantages are widely used in the background of recent demands for higher welding efficiency.

[0003] Conventionally, flux-cored wires include N
A small amount of an alkali metal typified by a and K is added, whereby arc stability and spatter reduction are achieved. For example, a flux-cored wire disclosed in Japanese Patent Application Laid-Open No. 58-23595 is filled with a flux that has been granulated by adding water glass.
Alkali metals such as a and K are added. Further, in the flux-cored wire disclosed in Japanese Patent Publication No. 2-40435, the ratio of the amount of alkali metal added as an arc stabilizer and particularly the ratio of Na and K is specified, whereby the arc stability in a low current region is determined. It is said that improvement can be obtained. In this case, as raw materials of Na and K, powder raw materials such as soda feldspar, potassium feldspar, and potassium fluoride are used in addition to water glass (sodium silicate and potassium silicate).

[0004] By the way, even if the amounts of Na and K contained in the flux-cored wire are extremely small, they act sensitively on welding workability. For example, when Na or K is added from water glass, the segregation of Na and K for each individual granulated particle, and the use of a powder material containing Na and K occurs during the compounding process, during transportation, or during the filling process. Na, K
The segregation causes arc stabilizer component fluctuation in the longitudinal direction of the wire, destabilizes the arc during welding, increases the amount of spatter generated, and causes metal dripping in a vertical welding posture.

[0005]

Accordingly, the present invention provides a flux-cored wire in which a trace amount of an alkali metal component, particularly Na and K, which is added as an arc stabilizer, is uniformly contained in the longitudinal direction of the wire to obtain good welding workability. It is an object of the present invention to provide a flux cored wire.

[0006]

That is, the gist of the present invention is as follows.
In a flux cored wire for gas shielded arc welding in which a flux is filled in a steel sheath, one or two types of Na and K are added to the inner surface of the steel sheath with respect to the total weight of the wire in the range of 0.005 to 0.15. % Of a flux-cored wire for gas-shielded arc welding, wherein the flux-coated wire is characterized by having a film containing the same.

[0007]

The present invention will be described below in detail. The flux-cored wire according to the present invention is shown in FIGS.
(C) and (d) show a structure in which a film 3 containing Na and K is formed on the inner surface of a steel outer cover 1 so as to show a wire cross-sectional shape, and a flux 2 is further filled therein. This stabilizes the arc when welding is performed using the wire, and provides good welding workability. The coating does not need to cover the entire inner surface of the steel outer skin, but is formed almost continuously in the longitudinal direction of the wire. That is, since Na or K as an arc stabilizer in the longitudinal direction of the wire is formed almost uniformly and almost continuously on the inner surface of the outer skin, segregation of the arc stabilizer is small. As a result, the variation in the arc length is small over the entire length of the flux-cored wire, the arc is stable, the generation of spatter is small, and even in a vertical position, stable welding without metal dripping can be performed.

[0008] Na and K forming a film on the inner surface of a steel outer shell
One or two amounts of 0.005 to the total weight of the wire
０．１0.15%. If the amount of one or two types of Na and K exceeds 0.15%, the amount of spatters generated increases and the arc length increases, and the metal tends to sag, particularly in welding in the upward position. If the amount of one or two of Na and K is less than 0.005%, the effect of film formation is not clearly recognized and the arc becomes unstable.

The flux-cored wire of the present invention
It is also possible to mix Na and K components with a powder raw material and to incorporate them into the flux.
The sum of the amounts of a and K needs to be suppressed to 0.20% or less. The amounts of Na and K are used as the composition, concentration and steel shell of the water glass. It can also be adjusted by changing the inner surface roughness of the steel pipe or strip. The present invention also provides a flux-cored wire (FIG. 1 (a)) using a steel pipe and having no gap in the outer sheath, and a flux-cored wire (FIG. 1) manufactured by performing an electric resistance welding of the outer sheath after filling the flux using a steel strip.
(B)), it can be applied to any of flux-cored wires (FIGS. 1 (c) and 1 (d)) which are formed using a steel strip and have a gap in the outer skin. Hereinafter, the present invention will be described more specifically based on examples.

[0010]

EXAMPLES The steel sheaths (S1, S2) shown in Table 1 were filled with the fluxes (F1 to F4) shown in Table 2 to produce wires (W1 to W12, 1.2 mmφ each) shown in Table 3 as a trial. Using a water glass having a different composition and concentration on the inner surface of the steel outer skin, a film containing Na and K is formed by the method schematically shown in FIGS. 2 (a) and 2 (b), followed by flux filling and shrinking. Diameter was performed. In the figure, 3 is a coating on the inner surface of the steel outer skin, 4 is a steel pipe, 5
Is a water glass, 6 is a steel strip, and 7 is a film forming apparatus. These test wires were evaluated for welding workability by the test methods shown in Table 4. Table 5 summarizes the test results.

Wire symbols W3, W4, W6, W8, W
9, W10 according to the present invention showed a stable arc state in each welding position, and showed good welding workability without abnormal occurrence of spatter during welding and metal dripping. Wire symbols W1, W5 and W12 are N
In the case where the film containing a and K is not formed, there is a portion where the arc state becomes unstable during welding. At this time, the amount of spatter generated increases and metal dripping occurs in the upright posture,
Slag removability and bead shape deteriorated.

[0012] The wire symbol W2 cannot cover the fluctuation of the alkali component in the flux because the content of the alkali component in the coating is too small, and there is a portion where the arc state becomes unstable during welding. Metal sagging occurred in an increased amount and in a standing position. For the wire symbol W7, since the wire did not contain any of the arc stabilizers Na and K, the welding workability was extremely poor. For the wire symbol W11, since the total amount of Na and K in the coating formed on the inner surface of the steel sheath was too large, the amount of spatter generated was large, and metal dripping occurred in the upright posture.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

As described above, according to the flux-cored wire for gas shielded arc welding of the present invention, the arc stabilizer is coated almost uniformly on the inner surface of the steel sheath in the longitudinal direction of the wire. It is possible to obtain a flux-cored wire for gas shielded arc welding that is stable and has good welding workability such as a small amount of spatter.

[Brief description of the drawings]

1 (a), (b), (c) and (d) are views showing a cross-sectional shape of a wire according to the present invention.

FIGS. 2 (a) and (b) show Na and K in Examples.
It is a schematic diagram which shows the method of making each contain.

[Description of Signs] 1 steel outer skin 2 flux 3 steel outer skin inner coating 4 steel pipe 5 water glass 6 strip steel 7 coating equipment

Continuation of front page (56) References JP-A-6-304782 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/368 B23K 35/02

Claims (1)

(57) [Claims] 1. A flux-cored wire for gas shielded arc welding comprising a steel sheath filled with a flux, wherein one or two types of Na and K are added to the inner surface of the steel sheath with respect to the total weight of the wire. A flux-cored wire for gas shielded arc welding, wherein a coating containing 0.005 to 0.15% is formed.