JP2000079495A - Welding steel wire and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure superior bead height in multi-layer fillet welding between high electric currents and between high passes by obtaining arc stability and low spattering, in gas shielded arc welding. SOLUTION: The steel wire composition is such that it contains 0.035 wt.% or less C, 0.50-1.50 wt.% Si, 1.00-2.00 wt.% Mn, 0.22-0.50 wt.% Ti+Al, 0.0001-0.0030 wt.% K, and 0.015 wt.% or less O, and that the composition is adjusted so as to satisfy the formula, 0.1<=(K×C×100)/ O×(Ti+Al)}<=2.0. It is also desirable that the wire has the composition further containing Zr, Nb and V in the range not more than 0.55 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel wire for welding and a method of manufacturing the same, and more particularly to a gas shielded arc welding which stabilizes an arc and reduces the amount of spatters, and realizes an excellent bead shape. It is.

[0002]

2. Description of the Related Art A welding method using a shielding gas has been widely used in various fields such as automobiles, shipbuilding and construction due to the rapid spread of automatic welding. However, in actual welding work, there is a problem that spatter frequently occurs, and therefore, development of a low spatter wire has been awaited.

To meet the above demand, a method of reducing the amount of spatter generated by adding potassium has been proposed in Japanese Patent Application Laid-Open No. Hei 6-218574, but this method is effective in reducing spatter. Although you can see
Even so, it is difficult to say that it is sufficient, and there remains a problem in that a high bead height cannot be ensured in multilayer welding between high currents and high passes.

[0004]

As described above, the welding method using a shielding gas generates a large amount of spatter,
There was a problem that it was difficult to secure a bead shape. In particular,
In multi-layer fillet welding of steel plates at high currents and high passes, the bead shape and the goodness of the bulge are important factors that greatly affect work efficiency. The present invention has been developed in view of the above situation, and in gas shielded arc welding, it is possible to secure an appropriate bead height, not to mention stabilizing an arc and reducing spatter. With its advantageous manufacturing method.

[0005]

Means for Solving the Problems The inventors of the present invention have developed a welding wire which achieves a low spatter by adding K (potassium) as described above, while maintaining the spatter reducing effect while maintaining a high current and a high pass. As a result of intensive studies for the purpose of securing a good bead height in multi-layer fillet welding between steels, the following findings were obtained.

(1) In order to maintain the low spatter effect of a wire having K, further reduce the amount of spatter generated in a high current region, and secure the swelling of weld metal in fillet welding. , (Ti + Al) 0.22
wt% or more, C is set to 0.035 wt% or less, and (K × C × 10
It is necessary to adjust C, Ti, Al, K, and O so that 0) / {O × (Ti + Al)} is 0.1 or more and 2.0 or less.

(2) In particular, in order to secure the effect of reducing spatter in a high current region, it is preferable that Ca is contained at 0.0015 wt% or less, and the arc is stabilized by adjusting the amount of Ca to this range. In the high current region, further lower spattering is achieved.

(3) Further, if K exceeds 0.0030 wt%, the arc becomes unstable and the welding workability deteriorates. Therefore, it is necessary to limit the K content to 0.0030 wt% or less.

(4) Regarding the addition of K, an internal oxide layer is formed on the surface layer of the wire in an inert gas atmosphere during annealing during the wire drawing step, and K is diffused therein to stably maintain the oxide. Preferably.

(5) Thus, it is possible to further reduce the amount of spatter generated in a high current region while maintaining the effect of reducing spatter by the application of K, and to secure the swelling of the weld metal in fillet welding. Thus, it is possible to achieve both improvement in workability and high quality welding. The present invention
It is based on the above findings.

That is, according to the present invention, C: 0.035 wt% or less, Si: 0.50-1.50 wt%, Mn: 1.00-2.00 wt%, Ti + A
l: 0.22 to 0.50 wt%, K: 0.0001 to 0.0030 wt%, O: 0.0
15% by weight or less in a range satisfying the following formula (1) 0.1 ≦ (K × C × 100) / {O × (Ti + Al)} ≦ 2.0 --- (1), and the balance is substantially Fe It is a steel wire for welding characterized by becoming.

[0012] In the present invention, further in the wire
Ca: 0.0015wt% or less, and further Zr, Nb, V, Ti
+ Al + Zr + Nb + V: It is preferable to contain it in the range of 0.55% by weight or less.

Further, the present invention provides a method for producing a composition comprising: C: 0.035 wt% or less;
Si: 0.50-1.50 wt%, Mn: 1.00-2.00 wt%, Ti + Al: 0.
An aqueous solution of potassium salt is applied to the surface of a steel wire having a composition containing 22 to 0.50 wt%, and then annealed, and K and O are respectively K: 0.0001 to 0.0030 wt% O: 0.015 wt% or less. And, after forming an internal oxide layer containing a range satisfying the following expression (1) 0.1 ≦ (K × C × 100) / {O × (Ti + Al)} ≦ 2.0 --- (1)
This is a method for producing a welding steel wire, which comprises performing pickling, copper plating, and then drawing.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reason for limiting the wire composition to the above range in the present invention will be described. C: 0.035 wt% or less C is an important additive element for securing the strength of the weld metal, but has an adverse effect on the viscosity and fluidity of the molten steel. A satisfactory bead shape cannot be secured in fillet welding in the current range.
Therefore, the C content is set to 0.035 wt% or less.

Si: 0.50-1.50 wt% Si is an element which is indispensable mainly as a deoxidizing agent and for ensuring workability and slag removability.
If the amount is less than 0.50 wt%, these characteristics cannot be secured. On the other hand, if the content exceeds 1.50 wt%, the toughness of the weld metal cannot be ensured. Therefore, the amount was limited to the range of 0.50-1.50 wt%.

Mn: 1.00 to 2.00 wt% Mn, like Si, is an indispensable element for obtaining high strength and high toughness as a deoxidizing agent and also for ensuring workability. If it is less than wt%, these characteristics cannot be secured, while if it exceeds 2.0 wt%, sufficient slag releasability and bead shape cannot be secured, and the toughness of the deposited metal is reduced. Therefore, the Mn content is limited to the range of 1.00 to 2.00 wt%.

Ti + Al: 0.22 to 0.50 wt% Ti and Al are added as a deoxidizing agent and for the purpose of securing the strength of the weld metal and securing the weather resistance. In particular, in the high current range, it is effective for deoxidation, arc stabilization, and securing the bead height by improving the viscosity of the weld metal, but Ti + Al (Ti
And one or two selected from Al) is 0.22wt%
If it is less than 0.50 wt%, the effect is poor. On the other hand, excessive addition of more than 0.50 wt% causes a decrease in the toughness of the reheated portion of the weld metal.
The amount of Al was limited to the range of 0.22 to 0.50 wt%.

K: 0.0001 to 0.0030 wt% K reduces spatter, but tends to form a thin, convex bead by increasing the energy at the center of the arc. If K is less than 0.0001 wt%, the effect of reducing spatter is reduced. Addition in excess of 0.0030 wt% increases the arc length and spread, failing to obtain a satisfactory bead. Conversely, the occurrence of spatter is increased. Therefore, the amount of K is
It was limited to the range of 0.0001 to 0.0030 wt%. Since K has a low boiling point of about 760 ° C and has very low retention at the molten steel stage, it is extremely difficult for K to be present in the wire.
It can be added effectively by thermal diffusion in the annealing step described later.

O: 0.015 wt% or less O has an effect of reducing the amount of spatter,
There is a tendency that the oxidation of e and Ti is increased and the slag peeling property is hindered. If the content exceeds 0.015%, sufficient slag peeling property cannot be secured, and conversely, the generation of spatters increases. Therefore, the O content is 0.01
It was limited to 5 wt% or less.

Although the reasons for limiting the composition ranges of the respective components have been described above, it is not sufficient to simply limit the respective components to the above ranges in order to achieve the desired object of the present invention. In order to further reduce the amount of spatter generated in a high current region and to secure the swelling of the deposited metal in the fillet welding, the following equation (1) 0.1 ≦ (K × C × 100) / ｛O × (Ti + Al)｝ ≦ 2.0 --- It is necessary to adjust the amounts of C, Ti, Al, K and O so as to satisfy the relationship (1). In other words, if the value of equation (1) is less than the lower limit, there is no effect of reducing the amount of spatter generated in the high current region, and if the value of equation (1) exceeds the upper limit, welding occurs in high current fillet welding. It is not possible to secure the swell of metal. In particular, in fillet welding of high current using carbon dioxide gas as a shielding gas, in order to secure the swelling of the deposited metal, it is important to suppress the value of equation (1) to 2.0 or less. The gas shielded arc welding includes the above-described carbon dioxide gas shielded arc welding, as well as MAG welding using a mixed gas of Ar, CO ₂ , O ₂ , He and the like as a shielding gas.

Although the essential components have been described above, other components described below can be contained as required in the present invention. Ca: 0.0015 wt% or less Ca contributes effectively to the stabilization of the arc when added in a small amount. However, when added in excess of 0.0015 wt%, not only the slag peeling property is impaired, but also the amount of spatter generated increases. There is a tendency. Therefore, Ca is contained at 0.0015 wt% or less.

Ti + Al + Zr + Nb + V: 0.55 wt% or less All of Zr, Nb and V are added as necessary for the purpose of securing the strength of the weld metal and securing the weather resistance, similarly to Ti and Al. However, since excessive addition causes a decrease in toughness, when it is contained, it is contained in a range where the total amount of (Ti + Zr + Al + Nb + V) is 0.55 wt% or less.

In addition, Cr, Ni, Mo, Cu, B and the like can be added as needed for the purpose of securing the strength of the weld metal and securing the weather resistance. However, excessive addition causes a decrease in toughness.
%, Ni: 3.0 wt% or less, Mo: 0.50 wt% or less, Cu: 3.
The content is preferably not more than 00 wt% and B: not more than 0.005 wt%.

Incidentally, impurities such as P, S, and N are as follows.
Since the toughness of the weld metal is reduced, it is preferable to reduce as much as possible. In particular, S reduces the viscosity of the molten metal and has a bad effect on the bead shape in fillet welding in a high current region. Therefore, S is desirably 0.035 wt% or less, preferably 0.010 wt% or less.

The molten steel adjusted to the above-mentioned preferable composition is preferably made into a billet by continuous casting, and then into a steel wire by hot rolling. Then, after cold drawing and annealing by dry method, pickling, copper plating and wire drawing are performed to obtain a product. In the present invention, in the above annealing step,
As shown in FIG. 1, it is most effective to form an internal oxide layer on the surface layer of the wire and to hold K as a constituent element. This is because it is extremely difficult for K to be present in the wire because K has a low boiling point of about 760 ° C and the yield in the molten steel stage is extremely low. This is because K can be effectively contained.

The atmosphere in the above annealing treatment is as follows.
An inert atmosphere such as nitrogen gas is preferable. In this inert gas atmosphere, the moisture of the wire, the oxide film on the surface, or a small amount of oxidizing gas (CO ₂ , H ₂ O, O ₂ ) contained in the atmosphere
Thereby, an internal oxide layer is formed on the surface layer of the steel strand, and K is diffused into the internal oxide layer to stably maintain it as an oxide. As for the application of K, means for applying to the final product or applying from a wire drawing lubricant is also an effective means, although the stability and uniformity of K are somewhat lacking. Thereafter, the product may be subjected to pickling, copper plating, and wire drawing according to a conventional method to obtain a product.

[0027]

EXAMPLE A steel bloom (Cu) having the composition shown in Tables 1 and 2 was used.
(Including the adhesion amount by subsequent plating) was made into a steel wire of 5.5 to 7.0 mmφ by hot rolling, and then the wire diameter was set to 2.0 to 2.8 mmφ by cold drawing. Then 2-30
% Aqueous solution of 3 potassium citrate, then O ₂ : 20
0 ppm or less, CO ₂ : 0.1% or less in N ₂ atmosphere (dew point: −
(2 ° C or less) to 750 to 950 ° C, and adjust the wire diameter, potassium salt concentration, and the heating temperature and time to adjust the amount of oxygen and potassium due to the internal oxidation of the wire. The steel wire for welding of 1.2 mmφ was manufactured by performing wire drawing. The surface of the welding steel wire is coated with 0.4 to 1.7 g of lubricating oil per 10 kg of wire.

The multi-layer fillet welding between the high current and high pass was performed using the welding steel wire thus obtained.
Table 3 shows the results of investigation on the amount of spatter and the bead shape. The welding was performed at a rate of 20 l / min using 100% CO ₂ as a shielding gas, and the welding current: 380 A, voltage: 38 V, welding speed: 35 cm /
Under the condition of min, fillet welding of three layers and six passes was performed on a T joint having a thickness of 19 mm. Here, the amount of spatter
It was set to 1.5 g / min or less. In particular, it was rated good (○) when it was 1.2 g / min or less, acceptable (/) when it exceeded 1.2 g / min and 1.5 g / min or less, and unacceptable (x) when it exceeded 1.5 g / min. The target value of the height (H) with respect to the width (W) of the bead was set to 0.4 or more. In particular, a value of 0.5 or more was regarded as good (○), a value of less than 0.5 was considered as acceptable (△), and a value of less than 0.4 was considered unacceptable (×).

FIGS. 2 and 3 show (K ×
The relationship between C × 100) / {O × (Ti + Al)}, H / W, and the amount of spatter is shown.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

As is evident from Table 3, when steel wires (Nos. 1 to 32) satisfying the requirements of the present invention are used, the amount of spatter generated is small, and the welding is also excellent at high speed. A bead shape was obtained.

On the other hand, among the comparative examples, No. 37 and No. 40 were spattered frequently because (K × C × 100) / {O × (Ti + Al)} was less than 0.1, and No. 41 was ( K × C × 100
) / {O × (Ti + Al)} was more than 2.0, so that a satisfactory bead shape could not be obtained. No.34, 35
Since (Ti + Al) <0.22 wt%, spattering occurred frequently and a satisfactory bead shape could not be obtained. Further, in No. 33, spatter occurred frequently because C> 0.35 wt%. In addition, No. 36 has a Ca content of more than 0.0015 wt%, and No. 37 has a K content of less than 0.0001 wt%.
Since the K content exceeded 0.0030 wt%, spatter occurred frequently in each case. In No. 39, the effect of reducing spatter could not be obtained because the O content exceeded 0.020 wt%.

[0035]

As described above, according to the present invention, in gas shielded arc welding, the arc stability is excellent, the amount of spatter generated is extremely small, and the amount of spatter generated in a high current region can be effectively reduced. Rather, it is possible to secure the swelling of the weld metal in fillet welding, and as a result, it is possible to achieve both improvement in workability and improvement in welding quality.

[Brief description of the drawings]

FIG. 1 is a view showing an internal oxide layer in a wire surface layer portion.

FIG. 2 is a graph showing a relationship between (K × C × 100) / {O × (Ti + Al)} and a bead shape (H / W).

FIG. 3 is a graph showing the relationship between (K × C × 100) / {O × (Ti + Al)} and the amount of spatters generated.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/14 C22C 38/14 (72) Inventor Shuichi Sakaguchi 1-chome Mizushima Kawasaki-dori (Kurashiki City, Okayama Prefecture) (In) Mizushima Works, Kawasaki Steel Co., Ltd. (72) Inventor Yoshitaka Sasa 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome Kawasaki-dori (without address) F-term (reference) at Kawasaki Steel Corporation Mizushima Works 4E084 AA24 AA44 CA24 CA25 CA38 DA33 HA01

Claims (4)

[Claims] C: 0.035 wt% or less, Si: 0.50-1.50 wt%, Mn: 1.00-2.00 wt%, Ti + Al: 0.22-0.50 wt%, K: 0.0001-0.0030 wt%, O: 0.015 wt% or less In the range satisfying the following formula (1): 0.1 ≦ (K × C × 100) / {O × (Ti + Al)} ≦ 2.0 --- (1), and the balance substantially becomes Fe. A steel wire for welding, characterized in that: 2. The method of claim 1, wherein the wire further comprises Ca:
A welding steel wire having a composition containing 0.0015 wt% or less. 3. The welding steel wire according to claim 1, wherein the wire further has a composition containing Zr, Nb, V in the range of Ti + Al + Zr + Nb + V: 0.55% by weight or less. 4. A potassium salt is formed on the surface of a steel wire having a composition containing C: 0.035% by weight or less, Si: 0.50 to 1.50% by weight, Mn: 1.00 to 2.00% by weight, and Ti + Al: 0.22 to 0.50% by weight. After applying the aqueous solution, annealing is performed so that K and O are respectively K: 0.0001 to 0.0030 wt% O: 0.015 wt% or less, and the following formula (1) 0.1 ≦ (K × C × 100) / ｛O × (Ti + Al)｝ ≦ 2.0 --- After forming an internal oxide layer containing a range satisfying (1),
A method for manufacturing a steel wire for welding, comprising performing pickling, copper plating, and then drawing.