KR100776181B1 - Shielding gas, welding method by using the same and weldment thereof - Google Patents

Abstract

An object of this invention is to set suitable welding conditions, and to aim at deepening melting of a weld metal part, without reducing welding quality. That is, the present invention uses a shielding gas containing oxygen gas of 0.2 vol.% Or more (preferably 0.4 vol.% Or more) and helium gas as a balance, and the oxygen concentration in the welding metal is 70 to 700 ppm to weld metal. The depth of melting of the part is deepened, and the dimension ratio D / W value of the weld metal part is increased. According to the present invention, by welding at least one of the welding conditions having a suitable range of welding current, welding speed, and arc length, welding can be achieved without further deteriorating the welding quality.

Arc, welding, shield gas

Description

Shield gas, welding method and welded material using the same {SHIELDING GAS, WELDING METHOD BY USING THE SAME AND WELDMENT THEREOF}

1 is a graph showing the relationship between the oxygen concentration in the shield gas, the D / W value, and the oxygen concentration in the weld metal as a result of Example 1. FIG.

FIG. 2 is a graph showing in detail the oxygen concentration in the shield gas shown in FIG. 1 up to 1.0 vol.%.

FIG. 3 is a photograph showing a cross section of a welded metal part as a result of Example 1. FIG.

4 is a graph showing the relationship between the welding current, the D / W value, and the oxygen concentration in the weld metal as a result of Example 2. FIG.

FIG. 5 is a photograph showing a cross section of a welded metal part as a result of Example 2. FIG.

FIG. 6 is a graph showing a relationship between a welding speed and a D / W value according to the result of Example 3. FIG.

FIG. 7 is a photograph showing a cross section and a plane of a weld metal part according to the result of Example 3. FIG.

FIG. 8 is a graph showing a relationship between an arc length and a D / W value according to the result of Example 4. FIG.

FIG. 9 is a photograph showing a cross section and a plane of a weld metal part according to the result of Example 4. FIG.

Fig. 10 is a photograph showing characteristic cross sections and planes of the results of the rate change test of 0.6 vol.% Carbon gas according to the modification.

TECHNICAL FIELD This invention relates to the shielding gas for non-consuming electrode type gas shield welding, such as TIG welding, a welding method, and a to-be-welded object using the same, for example.

This application claims priority on the basis of Patent Application 2005-233162 for which it applied to Japan on August 11, 2005, and accepts the content here.

Conventionally, MAG welding (metal-arc active gas welding), MIG welding (metal-arc inert gas) as a method of welding a structure using a steel-based material such as carbon steel, stainless steel as a base material Welding (Metal-arc Inert Gas Welding), plasma welding and the like. Such welding is used when a weld metal part is deep and a high welding efficiency is required.

However, in MAG welding and MIG welding, there are disadvantages such as poor welding quality and easy welding defects. In addition, in plasma welding, in addition to the improvement degree, the tolerance of construction conditions was small and there existed a fault which is difficult to use in the field.

Moreover, as a welding method of that excepting the above, TIG (tungsten inert gas welding) welding is mentioned. TIG welding can be welded relatively easily and is widely used as a welding method for structures in which high quality welded metal parts are obtained and high reliability is required.

However, TIG welding has a problem that the melting depth of the weld metal is shallow, and it is necessary to increase the number of passes in order to deepen the weld metal portion, which takes time. In particular, in the highly versatile austenitic stainless steel, excessive heat input weakens the corrosion resistance, which is characteristic of the material due to the characteristics of the material, and also increases welding skew and also causes problems in welding construction. In addition, in the case of stainless steel and the like which are used nowadays, the S (sulfur) component, which is an impurity component in the material, is often decreased, and in TIG welding, the welding metal part forms a wider and shallower melt, resulting in insufficient welding. there is a problem.

For this problem, in order to deepen the melting depth of about one pass, the use of a mixed gas in which a small amount of oxidizing gas is added to the inert gas used as the shielding gas has been studied (see Patent Document 1, for example). .

Patent Literature 1 is a shield gas in which a small amount of oxygen gas is added to an inert gas such as argon gas, and the concentration of oxygen gas in the shield gas is, for example, 0.1 to 0.4 vol.% To deepen dissolution. The dimension ratio "dissolution depth D / bead width W" (D / W value) of the weld metal part at this time is about 0.7.

[Patent Document 1] Japanese Patent Laid-Open No. 2003-19561

However, only the conditions using the shielding gas in which 0.1-0.4 vol.% Of oxygen gas is mixed in the argon gas disclosed in Patent Literature 1 will not only deepen the melting depth of the weld metal portion, but also ensure the welding quality. There was no problem. That is, because other welding conditions are unknown or insufficient, it is difficult to realize welding in which the above-described D / W value is deeply melted to a value larger than 0.7.

In view of the above problems, an object of the present invention is to provide a shield gas that deepens the melting of a weld metal portion without deteriorating welding quality by setting appropriate welding conditions, a welding method using the same, and a welded object.

In order to achieve the above object, the shield gas according to the present invention is 0.2 vol.% Or more in the shield gas for non-consuming electrode type gas shield welding, which is welded by generating an arc between the electrode and the object to be welded. (Preferably 0.4 vol.% Or more) of oxidizing gas and the balance of helium gas.

In the present invention, by using the main gas as helium gas, it is possible to suppress the force (force) in which the convection direction of the molten paper in the weld metal acts from the inside to the outside under the influence of plasma airflow, and is 0.2 vol.% Or more. By containing the oxidizing gas (preferably 0.4 vol.% Or more), the surface tension becomes larger in the center of the surface than the outer periphery with the increase in temperature, and the convection of the molten pool also acts in the inner direction. Therefore, the high temperature redundancy below an arc value flows in a depth direction, and it melts deeply, and it is possible to make the dimension ratio D / W value of the weld metal part at this time into 0.8 or more (preferably 1.0 or more).

Moreover, in the welding method using the shielding gas which concerns on this invention, the to-be-welded object is welded using the above-mentioned shield gas. The welded material (welded object) includes metal such as stainless steel, for example.

It is preferable that a welding current is 100 A or more.

It is preferable that a welding speed is 3.5 mm or less per second.

It is preferable that arc length is 2.5 mm or less.

In the present invention, welding is performed using an oxidizing gas of 0.2 vol.% Or more (preferably 0.4 vol.% Or more) and a shield gas containing helium gas in the remainder, so that the D / W value can be increased and the melting is performed. It is possible to increase the depth.

In addition, the to-be-welded material which concerns on this invention is a to-be-welded object welded by the welding method using the above-mentioned shield gas, It is characterized by the melt depth with respect to bead width being 0.8 or more (preferably 1.0 or more).

In the present invention, since the weld shape of the weld metal portion is deeply melted and the melt depth with respect to the bead width is large, it is possible to ensure high welding quality.

Moreover, the to-be-welded object which concerns on this invention is a to-be-welded object welded by the welding method using the above-mentioned shield gas, It is characterized by the oxygen concentration in a weld metal being 70-700 ppm.

In the present invention, when the oxygen concentration in the weld metal is in the range of 70 to 700 ppm, since the convection direction of the molten pool becomes the depth direction from the surface center portion of the weld metal, deep melting can be realized.

Here, oxygen concentration in a weld metal means oxygen concentration in the weld metal part after welding.

EMBODIMENT OF THE INVENTION Hereinafter, implementation of the shield gas of this invention, the welding method using this, and a to-be-welded object is demonstrated based on FIGS. 1-10.

Shielding gas and the welding method using the same according to the embodiment is a shield gas of the non-consumable electrode type for gas shielded welding, which welding by raising an arc between the electrodes and avoid welds, 0.2 vol.% Or more ( Preferably, 0.4 vol.%) Of oxidizing gas and a shield gas containing helium gas as the balance are used.

Here, an oxidizing gas is a gas which dissociates in a high temperature arc and shows oxidative property, and oxygen gas, a carbon dioxide gas, etc. are used in consideration of the influence on a human body, etc. The shield gas can be adjusted by simply adding an oxidizing gas to the helium gas.

Thus, by making the main gas into helium gas, it becomes possible to suppress the force (force) which the convection direction of the molten paper in a weld metal acts from inside to outside under the influence of plasma airflow, and is 0.2 vol.% Or more ( Preferably, by containing 0.4 vol.% Or more of an oxidizing gas, the surface tension accompanying the increase in temperature becomes larger than the outer peripheral portion, and the convection (marangoni convection) of the molten pool also acts in the inner direction.

Therefore, the high temperature redundancy below the arc value flows in the depth direction to deepen the melting, and the dimension ratio D / W value of the weld metal part at this time is further improved than 0.7, which is disclosed in detail (described in detail in the examples). It is possible to set it to 0.8 or more (preferably 1.0 or more).

Also, since being so deep molten, thick blood weldment in Figure, or it can be welded in one pass to reduce the number of passes, it is possible to reduce the total heat input.

In the oxidizing gas concentration in the shielding gas, the D / W value is less than 0.8 when less than 0.2 vol.%. In addition, the oxidizing gas concentration in the shield gas has a constant D / W value between 8 and 10 vol.%. Since the degree of oxidation increases at the same time as the oxidizing gas increases, the upper limit of the oxidizing gas concentration is about 10 vol.%.

In addition, in the shield gas having a suitable oxidizing gas concentration, the welding current is 100 A or more (preferably 120 A or more), welding speed 3.5 mm / sec or less (preferably 2 mm / sec or less), arc length 2.5 mm or less (preferably Preferably, by welding while satisfying at least one of the welding conditions in the appropriate range of 1 mm or less), it is possible to improve the welding efficiency without increasing the welding quality and to increase the melting depth.

In addition, when the welding current is less than 100 A, the welding speed exceeds 3.5 mm / second, and the arc length exceeds 2.5 mm, the D / W value becomes less than 0.8.

The to-be-welded material which concerns on this embodiment is a to-be-welded material welded by the welding method using the shielding gas which has the appropriate oxidizing gas concentration mentioned above, and melt depth with respect to bead width is 0.8 or more (preferably 1.0 or more). At this time, the oxygen concentration in the weld metal is in the range of 70 to 700 ppm, and by setting it as this range, deep melting can be realized and high welding quality can be ensured.

Here, the oxygen concentration in the weld metal is the oxygen concentration of the weld metal part after welding as mentioned above. As a method of measuring the oxygen concentration in the weld metal, it is possible to measure the oxygen concentration of the weld metal part after welding, for example, using an inert gas fusion-infrared absorption method.

Thus, in order to support the shielding gas which concerns on this embodiment, the welding method using this, and a to-be-welded object, Examples 1-4 are demonstrated below.

EXAMPLE

First, the common conditions with respect to Examples 1-4 are demonstrated. As a to-be-welded material, SUS304 which is a low sulfur concentration (5 ppm of sulfur content, 10 ppm of oxygen content), and 10 mm of plate | board thickness stainless steel was used as a common prototype (base material). The components of the stainless steels are shown in Table 1.

TABLE 1

ingredient C Si Mn Ni Cr P S O Fe Content (mass%) 0.06 0.44 0.96 8.19 18.22 0.027 0.001 0.0038 Balance

In the welding method, the current polarity is DCEN, and the electrode material is W-2% ThO ₂ (tungsten electrode containing 2% tritium oxide), its electrode diameter is 2.4 mm, and the electrode tip angle is 60 °. It was set as the welding method. The shield gas is a mixed gas in which oxygen (O ₂ ), which is an oxidizing gas, is added to helium gas (He), which is an inert gas, in a shield gas for non-consumable electrode gas shield welding, and the flow rate thereof is 10 L / min. It was made. In addition, the nozzle used in Examples 1-4 was made into the single nozzle which makes a shield gas flow around the electrode.

Based on these common conditions, the oxygen gas concentration (vol.%) In the shield gas in Example 1, the welding current A in Example 2, the welding speed in mm 3 (mm / sec), the arc in Example 4 The length (mm) is changed for each of Examples 1 to 4, and the index indicating the obtained meltability, that is, the dimension ratio "melting depth D / bead width W" of the weld metal portion (hereinafter referred to as "D / W value"). The value of was confirmed. In addition, in the present Example, the D / W value obtained by Examples 1-4 is disclosed by Unexamined-Japanese-Patent No. 2003-19561, for example, and improved D / W value (bead width 5mm, 0.8 having an improvement value of 10% or more than 0.7, which is a melting depth of 3.5 mm), was evaluated as an index of the first criterion. Similarly, 1.0, in which the D / W value is 40% or more improved than 0.7, was used as the second criterion.

In the following, Examples 1 to 4 will be described in detail.

(Example 1)

In Example 1, as a shield gas, oxygen gas was added to helium gas, and the oxygen concentration in the shield gas was changed in the range of 0 to 10 vol.% To measure the D / W value, and the cross section of the weld metal part was observed. . The welding electrode 160A, the welding speed were 2 mm / sec, and the arc length was 1.0 mm, and other test conditions were based on the above-mentioned common conditions.

1 is a graph showing the relationship between the oxygen concentration in the shield gas and the D / W value according to the result of Example 1, Figure 2 is a graph showing in detail up to 1.0 vol.% Oxygen concentration in the shield gas of FIG. 3 is a photograph showing a cross section of a welded metal part according to the result of Example 1. FIG. 1 and 2 side by side the relationship between the oxygen concentration in the shield gas and the oxygen concentration in the weld metal. Table 2 shows the measurement results of Example 1.

Here, the oxygen concentration in the weld metal and the oxygen concentration of the weld metal part after welding are measured based on the inert gas fusion-infrared absorption method (JIS H 1620 (5)).

TABLE 2

As shown in FIGS. 1 to 3 and Table 2, the D / W value rapidly increased when the oxygen concentration in the shield gas was between about 0.1 to 0.2 vol.%. In addition, when the oxygen concentration in the shield gas was 0.2 vol.% Or more, the D / W value satisfied 0.8 or more, which is the first criterion. Particularly, in the case of 0.4 vol.% Or more, the D / W value is slightly below 1.0, which is part of the second judging criterion, between 0.4 and 1.2 vol.%, But becomes stable near 1.0 value, satisfying almost 1.0 or more. I can say that.

As shown in FIG. 1, the higher the oxygen concentration in the shielding gas as a whole, the larger the D / W value. As shown in FIG. 3, the weld metal portion has a narrower bead width W and a deeper melting depth D. It was confirmed that there was a tendency to form.

Therefore, the oxygen concentration in the shield gas is preferably 0.2 vol.% Or more (preferably 0.4 vol.% Or more).

In addition, the following guesses can be made regarding the effect of the oxygen concentration in the shield gas on the weld metal.

Usually, in order to deepen melting in a weld metal part, it is necessary to make the direction of the convection of a paper inward (the direction which flows in a depth direction from the surface center part of a weld metal part, and flows to a surface through a to-be-welded metal part). .

In general, surface tension flows from small to large, and the surface tension decreases at higher temperatures. Therefore, the surface center portion of the weld metal portion below the arc value becomes hot and the surface tension becomes smaller than the low temperature portion of the outer circumference portion, so that the convection of the molten pool acts outward. By adding a certain amount of oxygen gas (the same as carbonic acid gas) to the stainless steel used in this common specimen, the surface tension becomes larger than the outer periphery with the increase in temperature, and the convection of the molten paper is also inward. It will work. Therefore, since the hot redundancy below the arc value flows in the depth direction, the melting becomes deep.

In the result of Example 1, the shielding gas with a large D / W value and a deep melting can be confirmed. The oxygen concentration in the weld metal was 70 ppm or more when the oxygen concentration was 0.2 vol.% Or more. And it turns out that it becomes an almost constant value (about 700 ppm) between 8-10 vol.%. From this, it can be estimated that the above-mentioned convection direction reverses from the outward direction to the inward direction in the oxygen concentration in the weld metal in the range of 70 to 700 ppm, and by setting it as this range, deep melting can be realized.

(Example 2)

Example 2 added oxygen gas to the helium gas to make the oxygen concentration in the shield gas 0.4 vol.%, The welding speed was 2 mm / sec, the arc length was 1.0 mm, and the welding current was changed in the range of 80 to 250 A. D / W value was confirmed and the cross section of the weld metal part was observed. In addition, other test conditions were based on the above-mentioned common conditions.

4 is a graph showing a relationship between a welding current and a D / W value according to the result of Example 2, and FIG. 5 is a photograph showing a cross section of the weld metal part according to the result of Example 2. FIG. 4, the relationship between the oxygen concentration in the shield gas and the oxygen concentration in the weld metal is shown side by side. Table 3 shows the measurement results of Example 2.

TABLE 3

As shown in FIGS. 4, 5, and 3, when the welding current exceeds about 90 A, the slope of the graph of the D / W value increases, and as the welding current increases, the D / W value also increases. It became. And by setting it as 100 A or more, D / W value became 0.8 or more which is a 1st judgment standard. By setting it as 120 A or more especially, D / W value became 1.0 or more which is a 2nd judgment standard. Therefore, the appropriate value of welding current is 100 A or more, Preferably it is 120 A or more.

In the case of the welding current 90A where the rate of increase of the D / W value becomes large, the oxygen concentration in the weld metal is about 75 ppm, and at this time, it can be estimated that the convection direction in the weld metal changes from outward to inward.

In addition, FIG. 4 shows the result of the case where the shield gas is helium gas (pure He), and accordingly, the oxygen concentration in the weld metal is constant at about 20 ppm in the welding current range of 80 to 250 A. The / W value is decreasing above 80A. As a result, if oxygen gas is not added to the shield gas, since the oxygen concentration is not in the range of 70 to 700 ppm of the preferred weld metal in the first embodiment, it can be seen that convection reversal does not occur and the melting depth becomes shallow.

(Example 3)

In Example 3, the shielding gas was the same as in Example 2, the welding current was 160A, the arc length was 1.0 mm, the welding speed was varied in the range of 0.75 to 5.0 mm / sec, and the D / W value was confirmed. The cross section was observed. In addition, other test conditions were based on the above-mentioned common conditions.

6 is a graph showing the relationship between the welding speed and the D / W value according to the result of Example 3, Figure 7 is a photograph showing a cross section and the plane of the welded metal part according to the result of Example 3. Table 4 shows the measurement results of Example 3.

TABLE 4

As shown in FIG. 6, FIG. 7 and Table 4, at the welding speed of 3.5 mm / sec or less, the D / W value becomes 0.8 or more, which is the first criterion, in particular, the D / W value is less than 2.0 mm / sec. It was confirmed that it could become more than 1.0 which is 2 judgment criteria. Therefore, it was confirmed that the slower the welding speed, the deeper the melting. Therefore, it is preferable to set the welding speed to 3.5 mm / sec or less (preferably 2.0 mm / sec or less).

And as shown in Table 4, it was confirmed that the oxygen concentration in the weld metal at this time is 70 ppm or more as a whole.

In addition, although the graph when carbonic acid gas (mixed concentration 0.6 vol.%) Is used for oxidizing gas is shown in FIG. 6, the detail is demonstrated in the following modification.

(Example 4)

In Example 4, the shield gas was the same as in Examples 2 and 3, the welding current was 160A, the welding speed was 2.0 mm / sec, and the arc length was changed in the range of 1-7 mm to confirm the D / W value. , The cross section of the weld metal part was observed. In addition, other test conditions were based on the above-mentioned common conditions.

FIG. 8 is a graph illustrating a relationship between an arc length and a D / W length according to the result of Example 4, and FIG. 9 is a photograph showing a cross section and a plane of the weld metal part according to the result of Example 4. FIG. Table 5 shows the measurement results of Example 4.

TABLE 5

As shown in Fig. 8, by setting the arc length to 2.5 mm or less, the D / W value can be 0.8 or more, which is the first criterion. In particular, by setting it to 1.0 mm or less, the D / W value is the second judgment criterion. It could be confirmed that phosphorus could be 1.0 or more (see Table 5). That is, as shown in Fig. 9, when the arc length is longer than 2.5 mm, the arc width becomes wider, so that the melting depth D becomes deeper, but the bead width W becomes wider and the D / W value becomes smaller than 0.8. Turned out. Therefore, it is preferable that the arc length is 2.5 mm or less (preferably 1.0 mm or less).

Next, the effect | action which used helium gas in Example 1-4 mentioned above is demonstrated.

When helium gas was added, it was confirmed that the pressure applied to the surface of the molten paper of the weld metal was lower than that of argon gas. From this, it is considered that the plasma airflow of helium gas is smaller than that of argon gas. That is, it is estimated that the force (referred to as manpower) that the convection under the influence of plasma airflow of helium gas acts from inward to outward is also smaller than that of argon gas, and the force inhibiting the convection (direction of melting action) inward. It is possible to reduce. In addition, the marangoni convection acts more strongly inwardly by increasing the temperature to the center of the molten pool surface due to the contraction of the arc and increasing the temperature gradient.

Thus, in the present invention, the main gas is helium gas, so that the attraction force can be suppressed, and the melting depth is reduced by setting the welding current value, the welding speed, and the arc length in the preferred ranges identified in Examples 1 to 4 described above. It is possible to enlarge.

Next, the shielding gas of this invention, the welding method using the same, and the modification by the to-be-welded object are demonstrated based on FIG.

10 is a photograph showing characteristic cross sections and planes of the results of a rate change test of 0.6 vol.% Carbon dioxide gas according to a modification.

The oxidizing gas according to the present invention can exemplify carbon dioxide gas or the like in addition to oxygen gas. In a modification, the welding speed is changed in the same manner as in Example 3 by replacing the oxidizing gas of the shield gas used in the example from oxygen gas to carbon dioxide gas. The D / W value at the time of change was confirmed (refer FIG. 6).

The test conditions of the carbon dioxide gas shown in FIG. 10 are the welding speed of 2 mm / sec, and the welding current 160A. At this time, it was found that the melting depth became slightly shallow when compared with the result of the same conditions of 0.4 vol.% Oxygen gas (see FIG. 7).

In addition, the 0.6 vol.% Carbon dioxide gas shown in FIG. 6 had a smaller D / W value than the 0.4 vol.% Oxygen gas. Therefore, the effect that oxygen gas melts deeper than carbon dioxide gas is large. Therefore, it can be inferred that carbon dioxide gas needs to be added more than oxygen gas.

In addition, the 0.6 vol.% Carbon gas shown in FIG. 6 showed a graph trend almost identical to the 0.4 vol.% Oxygen gas. From this, it is conceivable that the carbon dioxide gas has almost the same effect as that of the oxygen gas. However, the same test as in Examples 1, 2, and 4 described above was performed on the shield gas to which carbon gas was added. It is desirable to confirm appropriate welding conditions such as current and arc length.

As mentioned above, although the shielding gas by this invention, the welding method using this, and embodiment and modified example of a to-be-welded thing were demonstrated, this invention is not limited to said embodiment and a modified example, The range which does not deviate from the meaning It is possible to deform in moderation.

For example, although it was set as the TIG welding method in embodiment and a modification, it is not limited to this. According to the results of Examples 1 to 4, it was confirmed that the effect of deep melting is an effect of helium gas, and the deep melting by adding an oxidizing gas to helium gas is caused by the change of the convection caused by oxygen in the weld metal and the melting. It was confirmed by the effect of reducing the attraction of the ground surface.

From this, the welding method is not limited to TIG welding and may be gas shielded arc welding in addition to MIG welding or MAG welding.

In addition, although the single nozzle was used in embodiment and a modification, it is not limited to this. For example, since the shield gas contains an oxidizing gas, the electrode tends to be lost by oxidation. In order to prevent this, a double nozzle consisting of an inner nozzle which supplies a shield gas from the periphery of the electrode generating an arc and doubles it in a concentric circle around the electrode, and an outer nozzle which supplies the shield gas from the outside of the inner nozzle It is preferable to use. For example, it is possible to flow a single helium gas from an inner nozzle close to the electrode, and to prevent the weakening of the electrode by adding oxygen gas or carbon dioxide gas to the outer nozzle on the outer periphery thereof, together with the D / W value. It is possible to make a higher value.

In this regard, in the first additional test, helium gas is combined with the inner nozzle, helium gas and oxygen gas is combined with the outer nozzle, and helium gas is combined with the inner nozzle, and helium gas and carbonic acid gas are combined with the outer nozzle in the second additional test. In the same manner as in Examples 1 to 4 described above, it is effective to check the concentration of the oxidizing gas, the welding current, the welding speed, and the arc length in the appropriate shield gas.

In addition, when helium alone is used as the shielding gas supplied from the inner nozzle, the starting property of the arc is poor. Therefore, it is preferable to improve the starting property by adding an appropriate amount of argon gas.

In addition, since the oxidizing gas is mixed with the helium gas, the surface of the hot welding portion is oxidized. Therefore, the oxidation can be improved and the appearance can be improved by, for example, adding 9% or less of hydrogen gas, preferably 3 to 7%. Therefore, the outer nozzle can obtain the same effect by putting an oxidizing gas into the gas of an inner nozzle.

In this regard, according to the above, helium gas and hydrogen gas are combined in the inner nozzle in the third additional test, helium gas and carbon dioxide gas in the outer nozzle, and helium gas and argon gas and the outer nozzle are in the inner nozzle in the fourth additional test. It is conceivable to combine helium gas, argon gas and carbon dioxide gas, and to combine helium gas and carbon dioxide gas in the outer nozzle, as well as helium gas, hydrogen gas and argon gases in the inner nozzle in the fifth additional test. Also in the same manner as in Examples 1 to 4, it is effective to confirm the concentration of the oxidizing gas, the welding current, the welding speed, and the arc length in the appropriate shield gas.

According to the shielding gas of the present invention, it is possible to make the melt depth deeper than the conventional improvement, and to increase the dimension ratio D / W value of the weld metal portion. Further, by deep melting in this way, even in the case of a thick welded object, it is possible to weld one pass or to reduce the total number of heat inputs because the number of passes can be reduced.

In addition, according to the welding method using the shielding gas of the present invention, D / W is welded by using an oxidizing gas of 0.2 vol.% Or more (preferably 0.4 vol.% Or more) and a shield gas containing helium gas as a balance. It is possible to increase the value and to increase the melting depth. In addition, by adding the oxidizing gas concentration contained in the shielding gas under appropriate conditions, for example, satisfies at least one of a welding current value, a welding speed, and an arc length within an appropriate range, thereby increasing the melting depth. It is possible.

Moreover, according to the to-be-welded object of this invention, since the welding shape of a weld metal part melts deeply, and becomes a shape with a big melting depth compared with bead width, it is possible to ensure high welding quality. And melting | fusing can be implemented deep by setting the oxygen concentration in a weld metal to the range of 70-700 ppm.

Claims (18)

delete delete delete A welding method for welding a welded object by using a shield gas containing 0.2 to 10.0 vol.% Of an oxidizing gas and a balance of helium gas, the welding method being 100 to 250 A, wherein the welding current is 100 to 250 A. . In the welding method for welding a welded object using a shield gas containing 0.2 to 10.0 vol.% Of an oxidizing gas and a balance of helium gas, the welding speed is 0.75 to 3.5 mm per second. welding method. A welding method for welding a welded object using a shield gas containing 0.2 to 10.0 vol.% Of an oxidizing gas and a balance of helium gas, the arc length being 1.0 to 2.5 mm, wherein the welding is performed using a shield gas. Way. delete The to-be-welded object welded by the welding method using the shielding gas of any one of Claims 4-6 WHEREIN: Melt depth with respect to bead width is 1.0-1.80, The to-be-welded object. delete The method according to any one of claims 4 to 6, The concentration of the oxidizing gas is 0.2 ~ 10.0 vol.% Welding method using a shield gas, characterized in that. The method according to any one of claims 4 to 6, A welding method using a shield gas, characterized by using a single nozzle. The method according to any one of claims 4 to 6, A welding method using a shield gas, characterized by using a double nozzle. The method of claim 4, wherein Welding method using a shielding gas, characterized in that the welding speed is 0.75 ~ 3.5mm per second. The method according to any one of claims 4, 5 and 13, Welding method using a shield gas, characterized in that the arc length is 1.0 ~ 2.5mm. A to-be-welded object welded by the welding method using the shielding gas according to any one of claims 4 to 6 and 13, wherein the weld depth to bead width is 1.0 to 1.80. The to-be-welded object welded by the welding method using the shielding gas of Claim 14 WHEREIN: The melted depth with respect to bead width is 1.0-1.80, The to-be-welded object. The welded object welded by the welding method using the shielding gas according to any one of claims 4 to 6 and 13, wherein an oxygen concentration in the weld metal is 70 to 700 ppm. The to-be-welded object welded by the welding method using the shield gas of Claim 14 WHEREIN: The to-be-welded object is 70-700 ppm of oxygen concentration in a weld metal.

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