JP2003326388A - Wire for gas-shielded arc welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire for gas-shielded arc welding of which the removability of slag can be improved without reducing the toughness of a weld metal. <P>SOLUTION: The wire for gas-shielded arc welding comprises, by mass, 0.03 to 0.10% C, 0.60 to 2.00% Si, 0.15 to 2.50% Mn, ≤0.03% P, ≤0.03% S, ≤0.03% O and 0.002 to 0.010% B, and the balance Fe with inevitable impurities, wherein the condition of 0.001<([Si%]/[Mn%])×[B%]≤0.005 is satisfied. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire for gas shielded arc welding, and more particularly, to an improvement in slag peelability without reducing the toughness of a weld metal. The present invention relates to a wire for gas shielded arc welding. [0002] A gas shielded arc welding method using carbon dioxide gas, argon gas and carbon dioxide gas as a shielding gas has a higher efficiency than other welding methods, and is therefore used for steel frames, truck frames and the like. Widely used for welding. The gas-shielded arc welding wire used in this welding method is required to have excellent toughness and weld cracking resistance of the weld metal, and also to have excellent slag peelability when coated on it. ing. [0003] slag generated by the gas shielded arc welding process, primarily serves a metal oxide of the SiO ₂ -FeO-MnO system, because it is non-conductive, when performing electrodeposition coating, in slag The paint does not spread on the covered part. Therefore, the slag remaining on the bead after welding is rubbed with a brush before painting, peeled off by hammering, or washed off with a water jet. It was necessary to spend and increase the water pressure of the water jet. [0004] Therefore, the present applicants have proposed a gas shielded arc welding wire having excellent slag releasability as follows:
0.12% or less, Si: 0.5 to 1.6%, Bi: 0.005 to 0.020% as required, Mn:
A compound containing 1.0% or less, P: 0.03% or less, S: 0.03% or less, and the balance consisting of Fe and unavoidable impurities was developed and filed as Japanese Patent Application Laid-Open No. 61-195793. [0005] Further, C: 0.15% or less, Si: 0.5
~ 2.5%, Mn: 1.0% or less, Zr, Ti and A
1 in total or two or more in total from 0.05 to 1.
0%, and if necessary, Bi, Sb and Nb.
One or two or more of them in total of 0.005 to 1.
A compound containing 0% and the balance consisting of Fe and inevitable impurities was developed, and a patent application was filed as Japanese Patent Application Laid-Open No. 62-124095. The above two inventions are both high Si-low M
By setting it to n, the generated slag is generally thin, fine, and easy to handle. Also, B
In the case where i, Sb or Nb is added, the slag is more easily peeled, and the occurrence of pits and blow holes is reduced, thereby preventing the occurrence of mechanical defects in the weld metal. However, those to which Bi was not added had a drawback that slag peeling properties were not sufficient, and those to which Bi and the like were added had a drawback that the weld crack resistance of the weld metal was reduced. Further, those to which Al and Ti are added have a disadvantage that slag removability is reduced. [0007] In order to improve the disadvantages of the above-mentioned Bi-added products, C: 0.10% or less, Si: 1.
20-1.80%, Mn: 0.15-0.85%, B
i: 0.03 to 0.20% and B: 0.001 to 0.
010%, P: 0.03% or less, S: 0.03%
%, Al: 0.02% or less, Ti: 0.02% or less, and the balance is made of a gas shielded arc welding wire composed of Fe and unavoidable impurities.
Patent No. 585 was filed. This wire for gas shielded arc welding has high Si-low Mn, and has improved the defect caused by adding Bi by adding B, that is, the decrease in welding crack resistance. However, the weld metal welded using the above-mentioned gas shielded arc welding wire has a problem that although the slag is easily peeled, the toughness is reduced. SUMMARY OF THE INVENTION An object of the present invention is to provide a wire for gas shielded arc welding capable of improving slag removability without reducing the toughness of a weld metal. In order to solve the above-mentioned problems, the present inventors have developed a method for removing slag without reducing the toughness of a weld metal welded using the above-mentioned gas-shielded arc welding wire. After diligent research on a method for improving the properties, ([Si%] / [Mn%]) × [B%]
Is set to more than 0.001 and 0.005 or less, it has been found that the slag removability is improved without reducing the toughness of the weld metal. The present invention has been made based on these findings. That is, in the wire for gas shielded arc welding of the present invention, C: 0.03 to 0.10%, S
i: 0.60 to 2.00%, Mn: 0.15 to 2.50
%, P: 0.03% or less, S: 0.03% or less, O:
0.03% or less and B: 0.002 to 0.010%, 0.001 <([Si%] / [Mn%]) ×
[B%] ≦ 0.005, with the balance being Fe and unavoidable impurities. Next, the components of the gas-shielded arc welding wire of the present invention and the reasons for limiting the content thereof will be described. C: 0.03 to 0.10% C is an element to be contained for improving the strength of the weld metal, promoting deoxidation, and suppressing the occurrence of blowholes. In order to obtain these effects, it is necessary to contain 0.03% or more.
If it exceeds 10%, spatters occur frequently and the welding workability deteriorates, so the content is made 0.03 to 0.10%. Si: 0.60 to 2.00% Si is added as a deoxidizing agent during the production of steel and improves the appearance of beets. Therefore, Si is an element to be contained therein. In order to obtain these effects, it is necessary to contain 0.60% or more.
If it exceeds 0%, the toughness of the weld metal deteriorates, so the content is set to 0.60 to 2.00%. Mn: 0.15 to 2.50% Mn is added as a deoxidizing agent in the production of steel, like Si, and also improves the toughness of the weld metal. Element. 0.15%, preferably 0.70% in order to obtain those effects.
%, But if it exceeds 2.50%, preferably 2.2%, the slag removability deteriorates, so the content is made 0.15 to 2.50%. P: 0.03% or less, S: 0.03% or less Since P and S are elements that easily cause weld cracking and lower the toughness of the weld metal, it is preferable that P and S be as small as possible. If the content is 0.03% or less, preferably 0.02% or less, there is little effect, so the content is made 0.03% or less, preferably 0.02% or less. O: 0.03% or less O is an element that lowers the weld crack resistance and the toughness of the weld metal. Therefore, it is preferable that O is as small as possible. Since it is small, its content is set to 0.03% or less. B: 0.002 to 0.010% B is an element contained for improving the weld crack resistance. To obtain the effect, 0.0
It is necessary to make the content 0.2% or more, but if it exceeds 0.010%, many pits will be generated on the surface of the weld metal. Therefore, the content is made 0.002 to 0.010%. Since Al, Ti and Zr have a strong deoxidizing action, they enhance the cleanliness of the weld metal, refine the crystal grains, suppress the occurrence of blowholes, and improve the mechanical properties of the weld metal. May be contained, if necessary. However, if the amount is too large, the slag removability decreases, so the allowable amount is 0.05% or less. Further, Bi, Sb, Nb, Se, Te and V may be contained as necessary, since they improve the slag peelability after welding and improve the workability of welding. However, if the amount is too large, the mechanical properties of the weld metal deteriorate, so the allowable amount is 0.05% or less. 0.001 <([Si%] / [Mn%])
× [B%] ≦ 0.005 [Si%] / [Mn%]) × [B%] is made larger than 0.001 because if it is 0.001 or less, the removability of the slag decreases. Further, the reason for setting the content to 0.005 or less is that if the content exceeds 0.005, the toughness of the weld metal decreases. Using a gas-shielded arc welding wire having the above composition, carbon dioxide gas as a shielding gas,
If a normal gas shielded arc welding method is performed using argon gas and carbon dioxide gas, the slag removability can be improved without lowering the toughness of the weld metal. Next, an embodiment of the present invention will be described. A commercially available JIS SM50A steel sheet having a thickness of 20 mm and subjected to buttering welding on a groove surface using a welding wire used in the main welding was used as a test base material. Welding was performed under the following conditions using a gas shielded arc welding wire having a component composition and using carbon dioxide gas as a shielding gas. As shown in FIG. 1, an impact test piece was sampled from the welded metal so that the notch and the part to be broken consisted of a weld metal.
Using this test piece, an impact test was performed according to JIS Z2242. The results are shown in Table 1 below. Welding conditions Welding current: 250 A Arc voltage: 35 V Welding speed: 60 cm / min Temperature between passes: 100-1
50 ° C In addition, the slag peeling property is as follows. The slag amount obtained by gently wiping the surface of the welded bead to which the slag adhered with a gloved hand and separating the slag was taken as A, and then collecting all the remaining slag with a metal brush. A / A
+ B. [Table 1] According to these results, in the example of the present invention, the absorption energy of the impact test value was 81 to 98 J, and the slag peeling ratio was 0.86 to 0.99. On the other hand, the Si content is lower than that of the present invention, and [Si%] /
Comparative Example 1, in which [Mn%]) × [B%] (hereinafter referred to as “x value”) is 0.001 lower than the present invention, has an absorption energy of 168 J, which is higher than that of the present invention. 0.64, which was about 74% or less of the examples of the present invention. Comparative Example 2, in which only the x value is 0.001 lower than that of the present invention, has considerably higher absorbed energy at 195 J than that of the present invention, but has a slag peeling rate of 0.78 and is about 91% or less of the present invention. there were. Comparative Example 3 in which the B content is lower than that of the present invention and the x value is 0.001 lower than that of the present invention.
Has an absorption energy of 185 J, which is considerably higher than that of the examples of the present invention. Comparative Example 4 in which only the B content is lower than that of the present invention
Has an absorption energy of 100 J, which is slightly higher than that of the examples of the present invention. Only the x value is higher than the present invention by 0.008 and 0.0
In Comparative Examples 5 and 6, which were 09, the slag peeling ratios were 0.98 and 1.0, which were almost the same as those of the present invention, but the absorbed energy was 42 J and 32 J, which was about 52% or less of the present invention. 40%
It was below. The x value is 0.008, which is higher than the present invention,
In Comparative Example 7 in which the Nb content was 0.50%, which was higher than that of the present invention, the slag peeling rate was 1.0, which was almost the same as that of the present invention. %
It was below. Comparative Example 8 in which the content of Si and Mn is greater than that of the present invention and the x value is 0.006, which is slightly higher than that of the present invention, has an absorption energy of 71 J and is about 88
%, And the slag removal rate was 0.74, which was about 86% or less of the examples of the present invention. The wire for gas shielded arc welding of the present invention having the above-mentioned structure has an excellent effect that the slag peeling property can be improved without lowering the toughness of the weld metal. Play.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram for explaining a method for producing and collecting an impact test piece in an example of the present invention.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Akio Kaminaka             Aichi Prefecture Nagoya City Minami-ku Daidocho 2-chome 30             Daido Steel Co., Ltd. (72) Inventor Hirotaka Minamikawa             Aichi Prefecture Nagoya City Minami-ku Daidocho 2-chome 30             Daido Steel Co., Ltd.

Claims (1)

Claims 1. In mass% (the same applies hereinafter), C: 0.03 to
0.10%, Si: 0.60 to 2.00%, Mn: 0.
15 to 2.50%, P: 0.03% or less, S: 0.03
%, O: 0.03% or less and B: 0.002 to
0.010%, and 0.001 <([Si%] /
[Mn%]) × [B%] ≦ 0.005,
A wire for gas shielded arc welding, the balance being Fe and unavoidable impurities.