JPH04197596A - Flux-containing wire for arc welding excellent in weldability - Google Patents

Abstract

PURPOSE:To maintain the stability of welding arc by regulating the contact between a flux wire and a feeder tip to a value in a specific range and also regulating contact electric resistance to a value in a specific range. CONSTITUTION:A wire, finish-wiredrawn to 1.2mmphi by means of roller die drawing or swaging without using a wiredrawing lubricant, is used. the contact pressure between a feeder tip and this wire is regulated to 1-50g/mm<2> and also contact electric resistance at a wire surface is regulated to 0.001-0.1OMEGA, by which spatter can be reduced and wire melting rate can be increased under stable arc, and, as a result, extremely superior weldability can be obtained. A figure shows a result of experiment on wire melting rate (dotted line) with respect to contact electric resistance at wire surface and also the amount of generated spatter (solid line) with respect to the above.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a flux-cored wire for arc welding, which has an outer sheath filled with flux and has good welding workability.

<Prior Art> Most conventional flux-cored wires have been so-called seamless wires with copper plating on the surface of the wires or rolled-up flux-cored wires using cold-rolled steel sheets. Since the former wire is copper-plated, the manufacturing cost is high, and the contact electrical resistance on the wire surface is too small, which slows down the welding speed and reduces welding efficiency. On the other hand, the latter wire usually has a diameter of 1 or 2 mmφ
A so-called baking process is performed to remove the lubricant used during wire drawing. As a result, Fe50. An oxide film mainly composed of is formed, resulting in poor electrical conductivity at the power supply tip and poor welding workability.

Various flux compositions have been developed for a long time, including the one disclosed in JP-A-49-15653, which has good welding workability. There is a problem in that the flux-cored wire for arc welding (hereinafter referred to as FCW) of the tube laquive filled with the flux tends to fluctuate. In addition, when annealing is performed to improve workability during wire drawing, oxidation, alteration, and decomposition of the deoxidizer and arc stabilizer in the flux occur, causing welding work within the loft and between lots. This causes problems such as variations in properties and deterioration, and a rough arc and a lot of spatter.

In order to solve this problem, the applicant of the present application has
-66092 publication [The specific electrical resistance (〃Ω・cm) obtained from the relational expression between the electric resistance (μΩ) of a wire of length Lcm, the wire length (cll), and the outer skin cross-sectional area (d) is
We have proposed a flux-cored wire for arc welding in which the resistance is limited to a range of 20 to 40 μΩ·cm.

However, there is a problem in that this electrical resistance changes due to fluctuations in the pressure at which the wire comes into contact with the power supply tip due to the nature of the wire, etc. when the wire is fed.

<Problems to be Solved by the Invention> The present invention has been made in view of the above problems, and provides a flux-cored wire that can maintain arc stability even when the contact pressure of the wire changes during wire feeding. The purpose is to provide

Means for Solving the Problems> To achieve the above object, the present invention provides a flux-cored wire for arc welding in which the outer sheath is filled with flux, in which the contact pressure with the power supply tip when feeding the wire is A flux-cored wire for arc welding with good welding workability, characterized in that the wire surface has a contact electrical resistance of 0.001 to 0.1 Ω within a range of 1 to 50 g/-.

Effect> In the present invention, the contact pressure with the feeder knob is within the range of 1 to 50 g/m as described above by drawing the wire up to 1.2 φ without using a wire drawing lubricant. By setting the contact resistance of the wire surface to 0.001 to 0.1 Ω, a flux-cored wire for arc welding with good welding efficiency and good welding workability can be obtained. Note that, as a wire drawing method that does not use a wire drawing lubricant, a well-known processing method such as roller drag or swaging can be used.

In the present invention, the reason why the rolling force is first limited to 1 to 50 g/lj is because the load applied to the power supply tip during welding was actually measured and found to be within the above range.

Next, the lower limit of contact resistance was set to 0.001Ω because if the contact resistance is below this value, the resistance at the wire protrusion becomes too small, so the amount of Joule heat generation is small, and as a result, the wire melting speed is reduced. On the other hand, the reason why the upper limit value of contact resistance is set to 0.1Ω is that if the contact resistance exceeds this value, the electrical conductivity at the power supply tip will deteriorate, and the power supply will become slower. This is because it becomes defective and welding workability deteriorates.

FIG. 1 shows the influence of the electrical resistance of the present invention on the wire melting rate and welding workability (here, the amount of spunter generation is taken as a typical characteristic value). As is clear from this figure, the contact resistance on the wire surface is 0.001Ω.
If it is below, the resistance at the wire protrusion becomes too small, so the amount of Joule heat generation is small, resulting in a slow melting rate of the wire and a low welding rate. Also, if the contact resistance exceeds 0.1Ω, the power supply chia 1
It can be seen that the electrical conductivity in the welding area deteriorates, leading to poor power supply and poor welding workability.

<Example> A general-purpose cold-rolled steel plate (JISS PCC) was used as the outer skin material, and a flux having the composition shown in Table 1 was manufactured at a filling rate of 15. In order to change the contact electrical resistance of the wire surface, the wire drawing methods were hole die wire drawing using lubricant, roller die wire drawing without lubricant, and waging processing to 1°2.
Welding tests were conducted using wires that had been finished drawn to mmφ.

As shown in Fig. 2, the welding test method is as follows: A flux-cored wire 4 fed from a wire feeding device 2 is passed through a power feeding tip 3 to a rolled steel plate for welding structures (JISSM41A) as the material to be welded 1. The wire welding speed and the amount of spatter generated were examined by beat-on-plate welding by applying electric power from the welding power source 5 in a downward position. ? The results of the close contact test are shown in Table 2.

As shown in Table 2, according to the present invention, unlike the comparative example, the contact electrical resistance of the wire surface is 0.00 even if the contact pressure of the power supply tip during wire feeding varies within the range of 1 to 50 g/-.
It was in the range of 1 to 0.1 Ω, with good arc and little spatter, and very good welding workability was obtained.

<Effects of the Invention> As explained above, according to the present invention, the wire melting rate can be increased under a stable arc, and good welding with less spatter can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the contact electrical resistance (Ω) of the wire surface and the wire melting rate (g/min), and FIG. 2 is a schematic diagram showing the situation of the welding test. 1... Material to be welded, 2... Wire feeding device, 3
...Power supply chip, 4...Wire, 5...Welding power source. Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] In a flux-cored wire for arc welding in which the outer sheath is filled with flux, the contact electrical resistance of the wire surface is 0 when the contact pressure with the power feeding tip during wire feeding is within the range of 1 to 50 g/mm^2. A flux-cored wire for arc welding with good welding workability, characterized by having a resistance of .001 to 0.1 Ω.