JP2950390B2 - Low spatter solid wire for gas shielded arc welding and method for producing the same. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low spatter solid wire for gas-shielded arc welding in which the surface layer is enriched with oxygen.

[0002]

_2. Description of the Related Art A single gas such as Ar, CO ₂ , He, or A
Ar-CO ₂ , Ar-O consisting of mixed gas of r, He, CO ₂ , O ₂ etc.
_2, Ar-He-CO ₂ shielding gas -O ₂ or the like is used in gas shielded arc welding. In order to reduce spatter during gas shielded arc welding using these shielding gases, several techniques for generating an oxygen-enriched layer made of an oxide on the surface of a solid wire have been proposed. The oxide present in the surface layer of the wire lowers the surface tension of the droplet during welding, and makes the droplet finer. Also,
Oxide has the function of smoothing the transfer of droplets to the base material by the arc stabilizing action of oxygen itself, thereby reducing the amount of spatter generated.

The following method has been disclosed as an oxygen enrichment method. A method in which an oxide is mixed in advance with the final product of JP-A-60-40685 or the lubricating oil at the wire drawing stage. A method of plating while leaving one part of the scale formed on the surface layer by annealing or the like in JP-A-59-110496. A method of enriching oxides on the surface by performing a heat treatment after plating as disclosed in JP-A-58-187298. ; JP-A-58-128294, 59-61592, 59-66996, 60-40685
In the method disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, annealing is performed at 200 to 950 ° C. to cause grain boundary oxidation.

[0004]

However, according to the above-mentioned method, it is difficult to make a uniform and sufficient amount adhere to the surface layer of the wire. In other words, it is difficult to uniformly mix oxides in the lubricating oil with the method described above, and the amount of the lubricating oil in the final product is only about 0.1% of the wire weight, and it is sufficient for low spatter There is a problem that it is difficult to uniformly attach an object.

In the method (1), it is difficult to apply sound plating in a state where the scale is uniformly and evenly attached to the wire surface. Therefore, it is necessary to partially leave the scale. In this case, there is a problem that it is difficult to control the amount of residual scale. If a heat treatment is applied after plating in the method described above, oxidation of the plating layer is inevitable. The amount of oxide on the surface of the wire and the electrical conductivity are contradictory.If a sufficient amount of oxide is secured for reducing the spatter, the electrical conductivity deteriorates, the arc becomes unstable, and the spatter can be reduced sufficiently. Absent.
In addition, depending on the amount of the enriched oxide, spatter may be increased.

According to the method, plating is performed after heat treatment and pickling, so that the plating layer is sound, and the effect of reducing spatter can be expected to some extent due to the oxide at the grain boundaries inside the plating layer. However, since the occurrence of grain boundary oxidation depends on the grain boundary pitch of the surface layer, the occurrence is generally coarser at 5 μm or more in the C direction and 100 μm or more in the L direction, making droplet transfer finer and reducing spatter. There is a problem that is not enough to achieve.

The present invention solves the above-mentioned problems, and provides a method for enriching oxygen in a form effective for reducing spatter on the surface of a solid wire without impairing plating properties.

[0008]

Means for Solving the Problems As a result of intensive studies, the inventors have found that the oxides can be enriched in a finer and more uniform form than in the grain boundary oxidation method and in a form more concentrated in the surface layer, thereby achieving the target. As a result of examining whether or not it is possible to reduce the sputtering, it was found that the target sputtering can be reduced by having the intragranular oxide layer in the surface layer.

That is, in the present invention, 0.10% by weight of Si
And / or a steel solid wire containing 0.20% or more of Mn, wherein the intragranular oxide layer has a depth of 2.5 μm or more in the surface portion of the wire, and the intragranular oxide layer has a diameter of 0.2 μm or more .
1 to 4 μm granular intragranular oxide is reduced to 0.1 to 3 μm
It is a low spatter solid wire for gas shielded arc welding characterized by being deposited at a high pitch and having 10 or more per 100 μm ² in cross-sectional area. 0.10% by weight of Si
Or more and / or steel solid wire containing 0.20% or more of Mn at 1000 ° C or more for 10 seconds or more, and 0.1 to 1.5% of steam
A method for producing a low spatter solid wire for gas shielded arc welding, comprising heating in an N ₂ atmosphere containing N ₂ gas to form an intragranular oxide layer on a surface layer.

[0010]

As described above, in order to reduce spatter during gas shielded arc welding, it is necessary to make droplet transfer finer. To do so, lower the surface tension of the droplet surface,
In addition, it is necessary that the arc be stable at all times. Therefore, it is ideal that the oxide is present as close to the surface layer as possible and uniformly at a high density.

In the grain boundary oxidized state, Fe oxides in which Si and Mn are concentrated near the grain boundaries are continuously grown on the grain boundaries in a state where the oxide density is not so high in the grains. . On the other hand, in the wire according to the present invention, a granular intragranular oxide is generated at a very surface portion of the wire. In the present invention, the intragranular oxide is
The term "granular oxide precipitated in the crystal grains" refers to a region (layer) in which such intragranular oxides are present, referred to as an intragranular oxide layer. The constituent elements of the oxide are Si, Mn,
Although the contents of Fe and O are judged from the result of the microscope measurement, the amount of the oxide is about three to five times that of the grain boundary oxidation.

[0012] The depth of the intragranular oxide layer from the wire surface
If the thickness is less than 2.5 μm, a sufficient reduction in sputtering cannot be achieved due to an insufficient amount of the oxide. In order to achieve a sufficiently low sputter, the depth of the intragranular oxide layer needs to be 2.5 μm or more. Also,
A granular intragranular oxide is generated in the intragranular oxide layer.
The number of granular intragranular oxides in this intragranular oxide layer
10 or more per μm ² . If the number of intragranular oxides per 100 μm ² in the intragranular oxide layer is less than 10,
As in the case of grain boundary oxidation, the pitch of the oxide is coarse, and it is not possible to sufficiently reduce the sputtering. The number of intragranular oxides is measured using a microscope with respect to the intragranular oxide layer having a cross section perpendicular to the longitudinal direction of the wire, and the value converted into the number per 100 μm ^{2 of} cross sectional area is used.

As a steel component, Si is less than 0.10% and / or
When Mn is less than 0.20%, neither intragranular oxidation nor grain boundary oxidation is observed. Therefore, it is necessary to contain at least one of Si and Mn at 0.10% or 0.20% or more, respectively. Further, in order to obtain an intragranular oxide layer, heating at 1000 ° C. or more for 10 seconds or more is required. In at the heating time is less than 10 seconds less than 1000 ° C., less than the depth of the intragranular oxide layer is 2.5 [mu] m, and becomes sufficient intragranular oxide number of cross-sectional area 100 [mu] m ² per intragranular oxide layer is less than 10 Low spattering cannot be achieved.
Therefore, the depth of the intragranular oxide layer from the wire surface
Heating at 1000 ° C. or more for 10 seconds or more is required to generate 10 or more intragranular oxides per m or more and 100 μm ^{2 in} cross-sectional area. The heating is preferably performed in an N ₂ gas atmosphere containing 0.1 to 1.5% (vol%) of water vapor.

As a manufacturing process, the steps of hot rolling → intermediate drawing → intermediate annealing → pickling → plating → finish drawing are common. The application of the surface oxide is generally performed during this intermediate annealing step, but if it has a grain boundary oxide, it always has a connection with the surface, so that it is partially peeled off by pickling and adversely affects plating. Gives and produces unevenness. Also,
In the case of having a grain boundary oxide, a finish wire after plating causes a pine-like horizontal plating crack on the wire surface. on the other hand,
Since the intragranular oxide in the wire of the present invention does not have a connection with the surface, the intragranular oxide is not removed by pickling, there is no adverse effect on the plating treatment, and there is no pine-like plating crack. .

[0015]

EXAMPLE After intermediate drawing of a hot-rolled finished wire having a diameter of 5.5 mmφ to 2.5 mmφ, a predetermined heat treatment was carried out, followed by pickling and plating, finish-drawing to 1.2 mmφ, and measuring the amount of spatter generated. In heat treatment, water vapor is generated to cause intragranular oxidation.
The 0.1% ~ 1.5% (vol% ) containing N ₂ gas was performed min 50 l ～100L feeding feeds. Table 1 shows the welding conditions when measuring the amount of spatter generation. CO ₂ and Ar-20% as shielding gas composition
Each condition of CO ₂ was evaluated. Further, the total number of generated spatters is collected, and the amount of spatter generated is evaluated based on the weight. The amount of spatter generated was calculated as CO ₂
2.0g / min or less for welding condition No. 1 using Al, and 0.2 for welding condition No. 2 using Ar-20% CO ₂ as the shielding gas composition.
The target value was 5 g / min or less.

[0016]

[Table 1]

The test results using wires having the chemical composition shown in Table 2 are shown in Tables 3 and 4 for the case where CO ₂ and Ar-20% CO ₂ are used as the shielding gas composition, respectively.
The depth of the intragranular oxide layer and the number of intragranular oxides can be determined by observing a cross section (C cross section) perpendicular to the longitudinal direction of the wire with a microscope (optical microscope or electron microscope). The internal oxide layer depth and granular intragranular oxide in the intragranular oxide layer were measured. Further, the results in Tables 3 and 4 show the amount of spatter generated, the depth of the intragranular oxide layer, and the cross-sectional area of 100 μm ^2.
1 and _{2 for} the case where the shielding gas composition is CO ₂ , and FIGS. 3 and 4 for the case where the shielding gas composition is Ar-20% CO ₂ , respectively. .

As apparent from these figures and tables, the wire of the present invention satisfies the target value of the amount of spatter generated.

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

In Table 3, CO ₂ was used as the shielding gas composition.
In Comparative Examples Nos. 14 to 19 using welding conditions No. 1 and the intragranular oxide layer depth was as shallow as 2 μm or less in Nos. 15 to 18, and the number of intragranular oxides was as small as 9 or less in Nos. 15 to 18, respectively. The sputter generation amount is 2.1 g / min or more, and a sufficiently low sputter has not been achieved.

In Table 4, the shielding gas composition A
In Comparative Examples No. 31 to No. 35 of welding condition No. 2 using r-20% CO ₂ , the intragranular oxide layer depth is as small as 2 μm or less, respectively, and the number of intragranular oxides in the cross-sectional area of 100 μm ² is also small. Since each of them is as small as 9 or less, their sputter generation amount is not less than 0.25 g / min, and a sufficiently low spatter has not been achieved. Si content 0.
In Comparative Examples Nos. 29 and 30, which used a low wire chemical composition of 08% and a Mn content of 0.16%, the intragranular oxide layer depth was as shallow as 1 μm or less, and the number of intragranular oxides in a cross-sectional area of 100 μm ² was also small. Less than one.

Comparative Examples No. 17, 18, Heating Temperature Below 1000 ° C.
19, 34 and 35 each have a shallow intragranular oxide layer depth of 1 μm or less, and the number of intragranular oxides in a cross-sectional area of 100 μm ² is as small as 8 or less. Comparative examples with heating time less than 10 seconds No. 14, 15, 16, 3
1,32,33 be shallower than intragranular oxide layer depth 2μm respectively, intragranular oxide number in the cross-sectional area 100 [mu] m ² even No.14 except small as 9 or less. In the wire of Comparative Example No. 31 shown in FIG. 5, after heating at 1200 ° C. for 5 seconds, grain boundary oxidation occurs at about 15 μm, and the pitch is coarse. On the other hand, in the wire of Example No. 24 shown in FIG. 6, after the heat treatment at 1200 ° C. for 10 seconds, fine intragranular oxides were uniformly and finely generated on the surface layer. FIG. 7 also shows an electron micrograph (× 3000) of the surface layer after the heat treatment using the wire of Example No. 24. 0.1 ~
4 μm intragranular oxides are precipitated at a fine pitch of 0.1 to 3 μm.

[0025]

According to the present invention, a fine, uniform and high-density intragranular oxide layer can be formed on the very surface layer of a steel solid wire. If this wire is used for gas shielded arc welding, Spatter generation can be significantly reduced. As a result, the work of removing spatter adhered to the work or the nozzle of the welding torch was remarkably reduced, and significant effects such as reduction in the number of maintenance steps and improvement in the work environment were obtained.

[Brief description of the drawings]

FIG. 1 shows the relationship between spatter generation and intragranular oxide layer depth when a steel solid wire having the chemical composition shown in Table 1 is welded under welding conditions No. 1 using CO ₂ as a shielding gas. It is a characteristic diagram.

Fig. 2 Spatter generation and the number of intragranular oxides per 100 µm ² cross section when a steel solid wire having the chemical composition shown in Table 1 was welded under welding conditions No. 1 using CO ₂ as a shielding gas. FIG. 4 is a characteristic diagram showing a relationship between

FIG. 3 shows the relationship between spatter generation and intragranular oxide layer depth when a steel solid wire having the chemical composition shown in Table 1 was welded under welding conditions No. 1 using Ar-20% CO ₂ as a shielding gas. FIG. 4 is a characteristic diagram showing the relationship of FIG.

FIG. 4 shows the amount of spatter generated and the cross-sectional area per 100 μm ² when a steel solid wire having the chemical composition shown in Table 1 was welded under the welding condition No. 1 using Ar-20% CO ₂ as a shielding gas. FIG. 4 is a characteristic diagram showing a relationship with the number of grain oxides.

FIG. 5 is an optical micrograph (× 1000) showing a metal structure of a surface layer of a wire of Comparative Example No. 31.

FIG. 6 is an optical micrograph (× 1000) showing the metal structure of the surface layer of the wire of Example No. 24.

FIG. 7 is a 3000 × electron micrograph showing the metallographic structure of the surface layer of the wire of Example No. 24.

Claims (2)

(57) [Claims] 1. A steel solid wire containing at least 0.10% by weight of Si and / or at least 0.20% of Mn by weight%,
In the surface layer portion of the wire, the intragranular oxide layer has a depth of 2.5 μm or more, and the intragranular oxide layer precipitates granular intragranular oxide having a diameter of 0.1 to 4 μm at a fine pitch of 0.1 to 3 μm.
A low spatter solid wire for gas shielded arc welding, wherein the wire has at least 10 pieces per 100 μm ² in cross section. 2% or more of Si by weight% and / or
A steel solid wire containing 0.20% or more of Mn is heated at 1000 ° C. or more for 10 seconds or more in an N ₂ gas atmosphere containing 0.1 to 1.5% of steam to form an intragranular oxide layer on a surface layer. Of low spatter solid wire for gas shielded arc welding.