JPH01150494A - Solid wire for gas-shielded arc welding - Google Patents

Abstract

PURPOSE:To maintain a stable arc, to smooth the transfer of globules, and to improve welding workability by specifying the composition of a wire, and concentrating a part of the components on the wire surface. CONSTITUTION:The wire contains, by weight, 0.01-0.15% C, 0.50-1.60% Si, 1.00-2.40% Mn, <=0.030% P, 0.004-0.030% S, 0.05-0.35% Ti, <=0.010% N, <=0.030% O, the balance iron, and other inevitable impurities. The wire surface is plated with copper. The content of at least one element among Si, Mn, S, and Ti and O is made higher than the average contents of the respective elements in the wire within a distance of 15mu of the wire surface to the wire center. As a result, the arc is soft, the globule formed on the wire tip diminishes in size, and the globule is smoothly transferred from the wire tip to the base metal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solid wire for arc welding used when performing arc welding using shielding gas, particularly when excellent welding workability is required during welding. This relates to solid wire for gas-shielded arc welding.

[Conventional technology]

When solid wire for arc welding is welded using shielding gas, relatively large-diameter droplets are formed at the tip of the wire.
This transfers to the base material due to grains or short circuits. This is because when the droplet migrates, large spatters are generated due to the effects of gas release from within the wire due to high temperature and arc force, and the arc condition is caused by the arc length, arc concentration, droplet migration state, etc. This is a phenomenon seen as a deterioration of arc stability.

There is a close relationship between this spatter generation and the arc condition.
As the droplets become larger, large spatter is more likely to occur.
Furthermore, when the droplets become large, the repulsive force of the arc causes the droplets to shake violently at the tip of the wire, making the arc unstable and disliked by welders.

There are also complaints that solid wire for gas-shielded arc welding has a harder bare arc than other welding materials using flux.

However, compared to arc welding that uses flux, such as welding with a coated arc welding rod or wire with a flank, solid wire for gas shielded arc welding does not use flux, the welding form is simple, and the wire is low cost. Currently, it is widely used because it is possible to weld continuously for a long time.

Therefore, a solid wire for gas shielded arc welding would be more preferred by welders if it had the above-mentioned so-called welding workability superior to that of the current state of the art.

As one of these solutions, for example, Japanese Patent Application Laid-Open No. 61-24
There is a wire described in Japanese Patent No. 2785. This is an example of an attempt to improve welding workability by improving the adhesion of lubricating oil on the wire surface to improve wire feeding during welding and to obtain a uniform arc condition. However, in this invention, the lubricating oil increases the amount of diffusible hydrogen in the weld metal, and there is a fear that the cracking resistance will deteriorate, so it cannot be said that it is necessarily a preferable wire.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned conventional drawbacks of solid wires for gas-shielded arc welding, and provides a wire that maintains a stable arc during welding, smoothes the transfer of droplets, and improves welding workability. It is something.

[Means for solving problems]

The gist of the present invention is that C: 0.01-0.15%, S
t: 0.50-1.60%, Mn: 1.00
~2.40%, P: 0.030% or less, S:
0,004-0.030%, Ti: 0.05-0.35
%.

N: 0.010% or less, O: 0.030% or less,
Or, in addition to this, Al1: 0.30% or less, the balance consists of iron and other inevitable impurities, the wire surface is copper plated, and the circumference is within 15μ from the wire surface excluding the copper plating in the direction of the wire center. Si in the inner part.

This is a solid wire for gas shielded arc welding, characterized in that the content of at least one element of Mn, S:T' i and 0 is higher than the average content of each element in the wire. That is, the solid wire for gas shielded arc welding of the present invention has its composition appropriately selected and limited, and
A part of the composition is concentrated on the surface of the wire.

[For production]

Next, the reason for limiting each component of the wire of the present invention will be described.

First, C tends to shorten the arc length and increase the number of short circuits due to an increase in Cl, thereby improving welding workability.

However, the upper limit was set at 0.15% because a large amount of C would cause deterioration of cracking resistance such as frequent sputtering and a decrease in toughness. If the C content is kept low, the short-circuit transferability tends to decrease slightly, but the amount of spatter generated decreases and the work to remove spatter after welding becomes easier. In addition, the arc state is softened,
It has the effect of reducing rapid arc fluctuations due to short circuits, and this effect is noticeable at 0.01% or more. Therefore, the lower limit was set at 0.01%.

St is essential as a main deoxidizing element to ensure the cleanliness and toughness of the weld metal, and by containing it at 0.50% or more, the arc is stabilized and a sound weld metal can be obtained. However, even if it is contained in a large amount, the amount of spatter increases due to the increase in the number of short circuits, and the toughness deteriorates, so the upper limit was set at 1.60%.

Mn is an element that contributes as a deoxidizing agent and increases the strength of the weld metal, and its effect can be obtained by containing it in an amount of 1.00% or more. However, if it is contained in a large amount, the amount of sputtering will only increase, so the upper limit was set at 2.40%.

P is an impurity, and since an increase in P causes a decrease in toughness, it is desirable to have less P, and it should not exceed 0.030%.

S is not only effective in reducing the amount of slag and spatter, but also has the effect of improving the bead shape, and this effect is observed at 0.004% or more.

If it exceeds 0.030%, it will be less effective in terms of improving the bead shape (the upper limit should be set at 0.030% because the sensitivity to high temperatures increases).
%.

Ti is an element effective in improving toughness and reducing the amount of spatter. Up to a Ti content of 0.05%, the amount of sputtering shows a sharp decreasing tendency, but after that it becomes saturated. Therefore, the lower limit was set at 0.05%. Similarly, the arc condition rapidly improves as the Ti content increases as the droplets become finer, but even if the Ti content is too large, it tends to saturate, so the upper limit was set at 0.35%.

Lower N content reduces the amount of spatter, maintains the arc state,
The upper limit was set at 0.010% because it is effective in improving the performance, but if the content is large, it not only causes blowholes but also tends to deteriorate the arc condition.

O content improves droplet transferability and is effective in reducing the amount of spatter generation and uniformity of bead waves, but a large amount of O content significantly reduces the toughness of the weld metal, so the upper limit should be 0.030%.
And so.

Furthermore, Al can be added to have a deoxidizing effect, preventing the generation of pores in the weld bead and refining the grain size, but if it exceeds 0.30%, the metal will become over-deoxidized, resulting in welding. Since the metal hardens significantly, the upper limit was set at 0.30%.

The reasons for limiting the components of the wire of the present invention have been described in detail above. Therefore, [C: 0.07%, Si: 0.77%, M
n: 1.65%, P: 0.015%, S
: 0.014%, Ti: 0.25%, N:
[0.0068%, O: 0.0080%] was used as a basic component, and wires were prototyped in which at least one element of St, Mn, S, and Ti and 0 were concentrated in various widths from the wire surface. In addition, when making wire prototypes, after melting and forging, the wire diameter is 5.
, 5 n++nφ hot-rolled raw wire is cold-rolled to 1.
The wire was drawn to 2φ and manufactured. Approximately 700°C during wire drawing
The wires were annealed at extremely high temperatures, and were copper-plated in the same manner as conventional gas-shielded arc welding solid wires for rust prevention, etc., and then used for testing.

As a result of observing welding workability such as spatter amount and arc condition using prototype wires with various concentration widths, as shown in Figures 1 to 5, we found that a range of 15μ from the wire surface excluding copper plating in the direction of the wire center. over the inner part of the circumference, Si, M
A wire in which n+ S , Ti, and 0 were enriched more than the average content of each element in the wire exhibited very good welding workability.

According to the wire of the present invention in which a part of the wire composition is concentrated on the wire surface, the welding arc changes from the conventional hard state to a soft state, and the size of the droplet formed at the wire tip is reduced. The transfer of these droplets to the base metal becomes smooth, and welding workability is greatly improved.

〔Example〕

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples.

Implementation - Chemical composition of upper wire is C: 0.07%, Si:
0.77%.

Mn: 1.65%, P: 0.015%,
S: 0.014%, Ti.

: 0.25%, N: 0.0068%, O:
0.0080%, covering the inner part of the circumference within a range of 15 μ in the direction of the wire center from the wire surface excluding copper plating,
St, Mn.

Using the wire of the present invention in which S, Ti, and 0 are concentrated in a higher amount than the average content of each element in the wire, and the comparative material in which these elements are not concentrated near the wire surface, the results shown in Table 1 were obtained. Downward bead welding was performed on 5M-50B steel under the welding conditions shown below, and the arc conditions of the two during welding were compared.

The arc state of the wire of the present invention is such that the droplet 2 formed at the tip of the wire 1 is small, and the droplet 2 does not shake violently at the tip of the wire 1, as shown in FIG. The transition was smooth, and there was little spatter. On the other hand, in the case of the comparative material, the droplet 2 formed at the tip of the wire 1 is large as shown in FIG. 4 also had large waves, and when the droplet 2 transferred to the base material 3, a phenomenon in which large spatter particles 6 were generated was observed. In addition, the wire of the present invention had less dull arc sound and a softer arc than the comparative material.

Ability side 1 2 C: 0.05%, Si: 0.80%, Mn:
1.80%, P: 0.009%, S: 0.0
11%, Ti: 0.13%, /l: 0.17%,
N: 0.0080%, O: 0.0124%
SB-50M wire was used under the welding conditions shown in Table 1.
Bead-on-plate welding was performed with the steel facing downward, and welding workability was compared. Although the wire of the present invention had a stable arc, little spatter, and good welding workability, it contained Si and Mn near the wire surface.

In the comparative material in which T1 and O were not concentrated, large spatter occurred, the arc was unstable, and the transfer of droplets was not smooth.

Table 1 Welding conditions [Effects of the invention] As described above, in the solid wire for gas-shielded arc welding of the present invention, the arc is soft and the droplets that form at the wire tip are small, and the droplets flow from the wire tip to the base metal. The transition will be smooth. Furthermore, it is easy for welders to use in semi-automatic welding, helps reduce fatigue during welding, and has extremely high utility value.

[Brief explanation of the drawing]

Figures 1 to 5 are diagrams showing the EPMA line analysis results measured from the wire surface to the center after removing the copper plating of the wire of the present invention, and Figures 6 and 7 are the arc states of the wire of the present invention and comparative materials. and FIG. 6 is a diagram showing a droplet transfer situation. 1... Wire, 2... Droplet, 3... Base material, 4...
- Molten pool, 5... arc, 6... spatter. Agent: Patent Attorney Masamitsu Akizawa and 1 other person Fig. 1 Fig. 71'2 Wire surface force/distance from (p7rL) Fig. 3 Wire surface force/distance from gtrn > Sui Otsu Fig. Distance from the surface with ヮFigure 7i'5 Figure Cpm from the wire surface

Claims (2)

[Claims] (1) C: 0.01-0.15% (weight%, same below)
, Si: 0.50-1.60%, Mn: 1.00-2.40%, P: 0.030% or less, S: 0.004-0.030%, Ti: 0.05-0. 35%, N: 0.010% or less, O: 0.030% or less, the balance consists of iron and other unavoidable impurities, the wire surface is copper plated, and the distance from the wire surface excluding the copper plating to the wire center direction is 15μ A solid wire for gas-shielded arc welding, characterized in that the content of at least one element of Si, Mn, S, and Ti and O in the circumferential inner part of the range is higher than the average content of each element in the wire. . (2) C: 0.01-0.15% (weight%, same below)
, Si: 0.50-1.60%, Mn: 1.00-2.40%, P: 0.030% or less, S: 0.004-0.030%, Ti: 0.05-0. 35%, N: 0.010% or less, O: 0.030% or less, and Al: 0.30% or less, with the balance consisting of iron and other unavoidable impurities, and the wire surface is copper plated. The content of at least one element of Si, Mn, S, and Ti and O in the circumferential inner part within a range of 15 μ in the wire center direction from the removed wire surface is higher than the average content of each element in the wire. Solid wire for gas shielded arc welding.