JPH08276273A - Butt welding method for clad steel - Google Patents

Abstract

PURPOSE: To enable even a double V groove to be welded by means of two layers of one run continuous welding on the high alloy side, in the butt welding of a clad steel, and to remarkably improve the efficiency of welding execution. CONSTITUTION: In this butt welding method for a clad steel, the abutting shape of the clad steel is a double V and in welding a high alloy steel 2 side, one run continuous welding is performed for the two layers, by combining GMAW method for the groove of a low alloy steel with a wire delta arranging type SAW method for the remaining groove of a high alloy steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butt welding method for clad steel.

[0002]

2. Description of the Related Art Clad steel is made of carbon steel and high-alloy steel layered on top of it. Unlike welding of ordinary carbon steel, it is necessary to use different welding materials for welding carbon steel and high-alloy steel. There is. In addition, even if the welding material is properly used, it is generally necessary to perform the welding in consideration of the following points when welding the clad steel.

First, in the welding of the carbon steel portion on the high alloy steel side, it is usually necessary to take care so that the carbon steel wire does not melt the high alloy steel portion. Because, if the high alloy steel portion melts even a little in the welding at this time, Ni, Cr, Mo, etc. of the high alloy steel are mixed in the weld metal,
This is because the composition forms a martensite structure or the like and leads to welding defects such as abnormally high hardness and cracks.

Next, a problem in welding a high alloy steel groove using a high alloy wire will be described. Usually, when selecting a wire to be applied to welding a groove portion of a high alloy steel of clad steel, that is, a welding material composition system, it is first necessary to grasp the composition of the high alloy steel which is a clad material. Next, the determination of the welding method is an important point, but at the same time, it is necessary to judge what to apply as the wire component system. For example, assuming that the composition system of the high alloy steel as the clad material is in the range from SUS316L system to INCOLOY825, JIS Z3324 (YS309Mo) is used for the former as a welding wire and JIS Z3334 (YNiCrMo-for the latter). 3) etc. are mentioned as candidates.

However, depending on the selection of the welding method, even if the above wire is applied, a sound welded portion may not always be obtained. This is because the welding of this portion also melts the groove portion of the high alloy steel of the clad material, but the weld portion of the carbon steel groove portion of the base material also melts at the same time, and the composition of the weld metal changes the composition of the wire and the alloy The tip portion and the carbon steel of the base are melted and agitated. Usually, the case where the wire components used in this way are mixed with carbon steel, high alloy steel or carbon steel to give a composition different from the original wire composition is called welding dilution. The degree of dilution (dilution rate) largely depends on the welding method, and the dilution rate is qualitatively determined from TIG, SMAW (covered arc welding), GMAW (gas shield arc welding), and SAW (submerged arc welding). Tend to grow in order.

Considering the above points, a special welding method is used in butt welding of clad steel. 5A to 5D are schematic views showing such a method. First, in FIG. 5 (a), after forming a groove on the carbon steel side 1, as shown in FIG. 5 (b), the high alloy steel portion 2 on the back side is formed.
Welding rod of carbon steel (SMA
Multi-layer welding using W). Next, as shown in FIG. 5 (c), after the butt portion on the high alloy steel side is chipped off, as shown in FIG. 5 (d), the welding rod (S
Weld using MAW).

As described above, the reason why the welding is performed with a small heat input on both the carbon steel side and the high alloy steel side is to keep the dilution rate low as described above, and the welding method is relatively small. The SMAW method, which allows welding with electric current, is often used. However, such a welding method is inefficient, and it seems that it will not be able to keep up with various demands for clad steel which will be increasingly required in the future.

For this reason, when welding clad steel, particularly in welding in a carbon steel groove on the high alloy steel side, a method for improving the welding efficiency while suppressing the dilution of the high alloy steel portion Is proposed. For example, such methods include those described in JP-A-59-137191, JP-A-61-226187, JP-A-63-10095 and the like. These methods are all U
This is a method of welding an OE clad steel pipe, but as shown in FIG. 6, the carbon steel 1 is provided with an X groove 3 '(a carbon steel groove outside the steel pipe),
3 "(the carbon steel groove inside the steel pipe) is provided, while the groove portion 4 (the inner high alloy steel groove) of the high alloy steel 2 is made wider than the groove 3" of the carbon steel 1 First, temporary welding 5 is performed on the groove 3'of the carbon steel 1 with the carbon steel wire,
Next, the groove 3 ″ of the carbon steel 1 is welded with a carbon steel wire from the high alloy steel 2 side to form a bead 6, and the remaining groove portion of the groove 3 ′ on the carbon steel side is further covered with the carbon steel wire. To form the bead 7, and finally, the groove portion 4 on the high alloy steel side is welded with the high alloy steel wire to form the bead 8. The welding method is the inner carbon steel. The SAW method (2 examples) and GMAW method (1 example) are applied to the groove, the SAW method is applied to all of the outer carbon steel grooves, and the SAW method using a strip electrode or a cored wire is applied to the inner high alloy steel groove. ing.

[0009]

However, the above method has the following problems. The first point is the problem of the groove shape. That is, when manufacturing a carbon steel pipe in the UOE process, the X-shaped groove is usually used. However, in the case of the above clad steel pipe, it is necessary to process the inner groove shape into a two-step groove, and it is not possible to use the existing bite (blade), so new capital investment and time loss required for changing the bite occur. Therefore, higher costs and lower manufacturing capacity are unavoidable.

The second problem is the groove shape and its weldability. First, when welding the inner carbon steel part, SA
Since the W method is adopted, there are problems from the following viewpoints. That is, the smoothness of the bead shape of the portion is important, and it is an essential condition that the high alloy steel portion is not melted. However, the welding arc is invisible in the SAW method. It is difficult to judge in real time whether the high alloy steel has melted. As a result, it was sometimes necessary to weld the high alloy steel groove before welding the high alloy steel groove and to rework the SAW bead with a grinder. Further, the SAW method using a strip electrode or a cored wire is applied in the welding of the groove portion of the next high alloy steel, but in the arc welding using the strip electrode, the arc is not uniform over the strip width, that is, wavy. The arc is likely to occur and a uniform weld may not be obtained. Furthermore, in SAW using a cored wire, the tip of the wire is placed in the center of the carbon steel weld bead in the front layer and welding is performed, so it is difficult to keep the dilution rate of the carbon steel weld low and perform welding.

The present invention has been made to solve the above-mentioned problems of the prior art. In butt welding of clad steel, the groove shape on the high alloy steel side is a versatile X type, and It is an object of the present invention to provide a welding method for a clad steel having a high efficiency and a low dilution rate, which enables one-run continuous welding in the two-layer welding on the high alloy steel side.

[0012]

In order to achieve the above object, the present invention has the following structures. (1) When butt welding the clad steel in which the high alloy steel is layered on the carbon steel, the width is 10 to 12 mm on the high alloy steel side,
While forming a groove whose depth from the surface of the high alloy steel is the sum of the high alloy steel thickness and the carbon steel thickness of 45 ± 5%, the root face thickness is 20 ± 5% of the carbon steel thickness and the carbon steel side For the X-shaped groove where the depth is the remainder of the carbon steel thickness and the angle is 70 to 120 °, the carbon steel groove on the high alloy steel side is used for the GMAW (gas shield arc). Welding), and the remaining high alloy steel groove is subjected to one arc continuous welding with high alloy steel wire, and then the carbon steel side groove is submerged with carbon steel wire. A butt welding method for clad steel characterized by welding.

(2) GMA of carbon steel groove on high alloy steel side
W uses a solid or cored wire having a diameter of 0.9 to 1.6 mm, welding current: 200 to 350 A, welding voltage: 26 to 38
The butt welding method for clad steel according to the above (1), wherein the butt welding is performed under the respective conditions of V.

(3) In the latent arc welding of the groove portion of the high alloy steel, the two wires connected to one power source are used as the leading electrodes, and the distance between the two wires is defined by the groove width of the above high alloy steel. 4 to 8 mm wide and arranged at right angles to the welding line direction. Further, one wire connected to one power source is used as a trailing electrode at the groove center and 5 to 20 m behind the leading electrode.
Place the wire at the position m, and the wire for both the leading electrode and the trailing electrode is 0.9 to 1.6 m.
Use solid or cored wire of m diameter, the condition of the leading electrode is current: 400-600A, voltage: 2
5 to 42 V, the following electrode has a current of 200 to 300 A,
The butt welding method for clad steel according to the above (1) or (2), which is carried out under each condition of voltage: 25 to 42V.

(4) GMA of carbon steel groove on high alloy steel side
Each condition of 1-run continuous welding of W and high alloy steel groove part of the arc welding is to set the welding speed to 30 to 60 cm / min, and to separate the gap between the GMAW and the preceding electrode of the latent arc welding by 300 mm or more. The butt welding method for clad steel according to any one of the above items (1) to (3), characterized in that

The present invention will be described in detail below. The clad steel targeted by the present invention has carbon steel as a base material, and has stainless steel or high Ni-based high alloy steel (for example, SU on its surface).
S304, Incoloy 825, etc.) are bonded as a joining material. In order to butt-weld clad steel, a groove is formed in the butt portion. FIG. 1 shows a groove shape according to the present invention. The clad steel Carbon steel 1 and thickness made of a high alloy steel 2 t ₂ (mm) of the thickness t ₁ (mm), the depth t ₃ in butting state 0.45 T ₁ ± 5%
+ T ₂ (mm), width W of high alloy steel surface is 10 to 12 mm
V-shaped groove 3 such that and t ₄ is 0.20 t ₁ ± 5
The angle θ ₂ to the carbon steel side through the root thickness of% (mm)
The V-shaped groove 4 is processed so that the angle becomes 70 to 120 °.

In the present invention, the basic shape of the groove is X as described above.
It is characterized in that it is made into a mold, but it has the following features on the high alloy steel side. That is, when the groove width W is set to 10 to 12 mm (constant) and the groove depth t ₃ is set within the above range, the groove angle θ ₁ ° changes depending on t ₁ and t ₂ . Normally, the thickness t ₂ of the high alloy steel portion of the clad steel is not likely to change as much as about ₂ to 4 mm, but t ₁ is highly likely to change depending on the use of the clad steel. In the present invention, the groove shape on the high alloy steel side is set in consideration of the change in the thickness of these clad steels. Incidentally, θ ₁ ° becomes smaller as t ₁ and t ₂ become larger,
_{As 1} and t ₂ become smaller, θ ₁ ° becomes larger.

The reason why the groove shape is within the above range will be described below. First, regarding the groove width W on the high alloy steel side,
This was set to 10 to 12 mm in combination with the arrangement of the special electrode during the latent arc welding of the high alloy steel described in the next section. Next, t ₃ was set to 0.45t ₁ ± 5% + t ₂ , but t ₃ was 0.
If it is less than 40 t ₁ + t _2, the groove cross-sectional area of the carbon steel part becomes too small, especially on the thin side of the total thickness of the clad steel, making it difficult to form good weld beads by the GMAW method described in the next section. Because. On the other hand, when t ₃ exceeds 0.50t ₁ + t ₂ , the groove cross-sectional area of the carbon steel portion becomes too large on the thick side of the total thickness of the clad steel, so that a good welding bead by the GMAW method is obtained. It is difficult to form.

Further, the root thickness t ₄ is 0.20t ₁ ± 5
%, But when t ₄ is less than 0.15 t ₁ , the GMA of the carbon steel groove portion on the thin side of the total thickness of the clad steel
This is because the frequency of burn-through in the W method increases, and conversely t
_{When 4} exceeds 0.25 t ₁ , the root thickness t ₄ becomes too large on the thick side of the total thickness of the clad steel, and a metal touch defect occurs during the latent arc welding from the last groove 4 side. Is.

Further, the groove angle θ ₂ ° on the carbon steel side is 70
The range was up to 120 °. This is because if θ ₂ ° is less than 70 °, the groove cross-sectional area becomes too small on the thin side of the total thickness of the clad steel, which makes it difficult to form good weld beads in latent arc welding. On the contrary, when θ ₂ ° exceeds 120 °, on the thick side of the total thickness of the clad steel,
This is because the groove cross-sectional area becomes too large, so that the welding speed must be reduced in order to secure the necessary amount of weld metal, and a decrease in welding efficiency cannot be avoided.

2A and 2B are views showing the welding process of the present invention. In welding, first, the weld bead 5 is formed from the carbon steel groove to the groove 3 on the high alloy steel side with the carbon steel wire (FIG. 2 (a)), but at this time, the high alloy steel portion does not melt. Need to be welded. The reason is that if the high alloy steel part melts to some extent, components such as Ni, Cr, and Mo of the high alloy steel are mixed in the weld metal, and the solidified structure forms martensite. This is because the hardness becomes abnormally high and welding defects such as martensite cracking occur. Therefore, in the present invention, welding of this portion is performed by the GMAW method (including CO ₂ , MIG, MAG, etc.).
Weld with. The GMAW method is a visible arc welding method, and because the welding arc and molten pool can be easily observed during welding,
It is possible to perform welding so that the high alloy steel portion does not melt, and it is possible to adjust the welding conditions as necessary to form a smooth weld bead.

The welding wire diameter for GMAW used in the present invention is in the range of 0.9 to 1.6 mmφ. The reason for limiting the wire diameter as described above is that it is difficult to stabilize the wire feeding when the wire diameter is less than 0.9 mmφ, and when the wire diameter exceeds 1.6 mmφ, the welding current needs to be increased more than necessary. Since it is difficult to perform stable welding on the thin side where the tip cross-sectional area is small, the wire diameter for GMAW is set within the above range. Further, the type of welding wire may be solid or cored wire.

The welding condition range of GMAW is welding current: 2
The range is 00 to 350 A and the welding voltage is 26 to 38 V. This is because the welding current deviates from the above range and the welding becomes unstable on the low current side, and conversely, the high-speed feedability of the wire becomes unstable on the high current side when it exceeds 350A. If the welding voltage is less than 26V, the generation of spatter becomes remarkable on the relatively high current side, and if it exceeds 38V, the welding arc length becomes too long and the arc acts on the groove portion of the high alloy steel. The high alloy steel part melts. Therefore,
The range of welding current and voltage conditions is as described above.

On the other hand, in the case of the latent arc welding method, it is difficult to observe the molten pool because the arc is invisible welding, and it is difficult to completely avoid melting of the high alloy steel portion. It is almost difficult to form a smooth latent arc weld bead in it. In the present invention, when the welding bead 5 is formed, at the same time, a high alloy wire is applied to the remaining high alloy steel groove portion as a special electrode to form the latent arc welding bead 6. That is,
Another feature is that the groove on the high alloy steel side enables continuous welding of two layers. Two-layer, one-run continuous welding is possible only when the preceding welding is MAGW, and when the preceding welding is latent arc welding, the flux is melted to form slag, and the slag covers the bead surface. Before welding the groove, slag must be removed. Therefore, by applying GMAW to the leading electrode as in the present invention, it is possible to perform one-run continuous welding on the high alloy steel side of the clad steel, and it is expected that the welding efficiency will be greatly improved.

In the above-mentioned two-layer one-run continuous welding, G
The distance between the MAW welding electrode and the latent arc welding electrode must be 300 mm or more. If the interval is less than 300 mm, the weld metal of the carbon steel portion of the first layer GMAW is not completely solidified, so that the weld metal easily mixes with the latent arc weld metal of the high alloy steel wire of the second layer, resulting in dilution. This is because the rate increases.

Next, after welding the high alloy steel side, as shown in FIG. 2 (b), the groove 4 on the carbon steel side is welded by the combination of carbon steel wire and the latent arc welding method, and the bead 7 is welded. To complete the welding of the clad steel. It is needless to say that the latent arc welding here can be applied from one electrode to multi-electrode welding, and the welding efficiency is improved as the number of electrodes is increased. It is not particularly limited because there are no elements that change significantly.

Next, a latent arc welding method using a special electrode in the groove portion of the high alloy steel on the high alloy steel side will be described. FIG. 3 is a diagram showing an outline of a welding device for obtaining the welding beads 6. The welding tip 8 has two welding wires 1 for high alloy steel fed from a wire feeder 10 connected to a welding power source 9.
1 and 12 are held and the welding tip 13 has a welding power source 14
One welding wire 16 for high alloy steel fed from the wire feeding device 15 connected to the above is held, and the tip of each wire is projected on the surface of the high alloy steel to have a length of 15 to 25.
Set so that it is in the range of mm. At that time, the distance between the two wires 11 and 12 fed from the welding tip 8 is
The groove width of the high alloy steel is set to be 4 to 8 mm wider and set so as to be perpendicular to the welding line. Wire 1
The reason why the lower limit of the distance between 1 and 12 is 4 mm is that in order to prevent this, the welding arc from the wire directly acts on the carbon steel and the dilution ratio of the carbon steel and the welded portion becomes large below this. On the contrary, if the distance exceeds 8 mm, it becomes difficult to secure a good weld bead shape. In addition, the wire 16 fed from the welding tip 13
5 to 15 m behind the welding line of the wires 11 and 12
The wire protrusion length is set to be in the range of 15 to 25 mm at an intermediate position of m, and the latent arc welding of the groove portion of the high alloy steel is performed.

FIG. 4 shows wires 11, 12 and wire 16.
4A, the wires 11 and 12 are arranged at right angles to the seam welding direction (arrow), and the wire 16 is 5 to 20 mm behind the wires 11 and 12.
Wire 11 and wire 1 at the position
It is the basis of the present invention that it is arranged at an intermediate position between two intervals (hereinafter, the method is referred to as a wire delta type arrangement of a latent arc welding method). That is, by arranging in this manner, the preceding two wires 11 and 12 melt the high alloy steel so that the welding arc does not directly act on the weld portion of the carbon steel portion, and are fused with the welding wire. To fill both ends of the groove of the high alloy steel to form the molten pool 17. Further, the one welding wire 16 in the trailing portion acts to increase the amount of welding of the molten pool 17 formed of the leading wire, and thus the welding speed can be easily improved. However, as shown in FIG. 4 (b), when the leading electrode and the trailing electrode are arranged too far apart from each other, the molten pool formed by the leading electrode and the molten pool formed by the trailing electrode are independent of each other. Formed, and welding defects such as slag inclusion easily occur. On the contrary, when the arrangement distance is extremely close, as shown in FIG. 4 (c), there is only one molten pool, but since the welding arc of the trailing electrode directly acts on the weld metal of the carbon steel portion, The dilution ratio of the low alloy portion increases, and the corrosion resistance, which is a main characteristic of the weld metal, is impaired. Therefore, the dimensions of the wire delta arrangement are in the above range.

According to the present invention, since the welding arc of the leading electrode does not act directly on the carbon steel portion in this way, and the welding arc of the trailing electrode acts on the molten pool formed by the leading electrode, the low dilution rate is obtained. Weld metal can be obtained, and since a high welding amount can be secured, it is possible to improve welding efficiency. on the other hand,
As the welding wire, a high alloy type welding wire containing a larger amount of alloying elements than the high alloy steel is used. For example, the component of the high alloy steel portion of the clad steel is Incoloy 825 (40% Ni).
-20% Cr-3% Mo), the welding material is Inconel 625 (60% N) considering dilution from the carbon steel part.
i-20% Cr-9% Mo) system is used. The diameter of the wire is set in the range of 0.9 to 1.6 mmφ for both the leading electrode and the trailing electrode, and the type of wire may be solid or cored wire. The reason for setting the wire diameter in the above range is the same as in the case of GMAW.

The welding conditions are as follows: welding current of the leading electrode is 400-600 A, welding voltage is 25-42 V, welding current of the trailing electrode is 200-300 A, welding voltage is 25-4.
The range is 2V. On the high current side where the welding currents of the leading electrode and the trailing electrode deviate from the above range, the penetration depth increases and the dilution rate of the welded portion of carbon steel increases, which is not preferable.
On the contrary, on the low current side outside the above range, the dilution rate is small, but the welding speed must be extremely slowed down in order to obtain an appropriate amount of welding, resulting in inefficiency. The reason for setting the welding voltage in the above range was determined from the viewpoint of bead shape forming ability and internal quality.

On the other hand, the welding speed of the two-layer one-run continuous welding is set in the range of 30 to 60 cm / min. The basic feature of the present invention is that the two-layer welding of the carbon steel groove portion and the high alloy steel groove portion on the high alloy steel side is completed by continuous welding for one run. In order to make this possible, as described above, the groove shape and the welding method were examined. In that case, from the viewpoint of weldability, especially in the GMAW method of the carbon steel part, spatter generation and bead forming ability, and in the latent arc welding method of high alloy steel, the dilution rate of the carbon steel portion, the bead forming ability, and the internal quality etc. As a result of ascertaining the welding speed limit that enables continuous one-run welding of both, it was found that good results can be obtained within the above range. This is because if the welding speed is less than the above lower limit, the welding speed is slow and the efficiency is remarkably reduced, and if the welding speed is higher than the upper limit, it is necessary to further increase the welding current.
W is not preferable because it causes frequent spatter and a high dilution rate in latent arc welding.

In order to make the present invention more effective, it is preferable to arrange the electrode angles of GMAW and latent arc welding at right angles to the seam welding line direction. This angle is acceptable up to a range of 5 ° in the front and back. If this angle is too large, the welding arc becomes unstable and the bead shape deteriorates. Further, the flux for latent arc welding may be either melt type or bond type.

[0033]

EXAMPLES Incoloy 8 having a total thickness of the components shown in Table 1 of 20 mmt (carbon steel thickness of 17 mm, high alloy steel thickness of 3 mm)
The 25 clad steel was processed by assembling various butt-shaped grooves as shown in Table 2 and assembled, and tab materials were attached to both ends of the welding line for testing (symbols of each groove are shown in FIG. 1). Corresponding to, test material length 1000mm, tab length 50
0 mm). Here, the reason why the butt groove shape is set as described above is that the two-layer, one-run continuous welding is an important point particularly for welding on the high alloy steel side.

The groove section A material has a groove depth t ₃ on the high alloy steel side.
Is set so as to be on the lower limit side of the range of the present invention, and conversely, for material B, t ₃ is set so as to be on the upper limit side of the range of the present invention. Further, the D and E materials were processed for comparison, and the D material was set so that t ₃ was less than the lower limit and the E material was set so that t ₃ exceeded the upper limit. The root thickness t ₂ and the groove width W on the high alloy steel side were constant at 3 mm and 11 mm, respectively. Furthermore, the groove angle on the carbon steel side is t ₃ so that the cross-sectional area of the groove does not change extremely.
The groove angle is small when the groove depth is small, that is, when the groove depth on the carbon steel side is deep, the angle is narrow, and conversely, when t ₃ is large, the angle is wide.

The welding was carried out by first performing continuous welding of two layers on the groove on the high alloy steel side of each groove material. The welding electrodes are arranged by placing the low alloy steel wire and the GMAW method at the welding start point in the center of the groove of carbon steel, and arranging them behind the welding line 4
SAW with wire delta arrangement on tab material at 00 mm position
The electrode is placed and the SAW flux is 50m in front of the electrode.
It was supplied from above the m position and welded. The wire arrangement of the wire delta arrangement type SAW has a wire interval of the leading electrode of 15 m.
m, the distance between the leading electrode and the trailing electrode of the SAW was 13 mm, and the protruding length of the wire from the welding tip was 20 mm.

The welding condition is that the welding speed for each groove is 2 for an arbitrary range of 30 to 50 cm / min.
The welding current and voltage were adjusted on the premise of continuous one-run welding of the layer. In particular, in the low alloy steel GMAW, the current was adjusted so that the amount of the deposited metal was 0.5 to 1 mm lower than the boundary with the high alloy steel so that the high alloy steel portion did not melt. After continuously welding the high alloy steel side, the groove portion on the carbon steel side was welded by latent arc welding with two electrodes, and welding of the clad steel was completed. Two
The conditions of the electrode SAW were such that the welding speed was changed according to each groove cross-sectional area to adjust the bead shape. The types of welding materials used are summarized in Table 3, and the welding conditions and results are summarized in Tables 4 and 5 (continued from Table 4).

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

In welding on the high alloy steel side, the test symbols A1 to A3 and B1 to B3 using the groove shape of the present invention are good two-layer one-run continuous welding in the welding speed range of 30 to 60 cm / min. Was possible. However, when the groove classification of the comparative method is C material, since the groove depth is shallow, the cross-sectional area of the groove portion of the low alloy steel becomes too small, and the occurrence of spatter and defective bead shape due to the use of low welding current. Occurrence of welding speed from 31 cm / min (test code C1) to 58c
Good welding could not be performed up to m / min (test code C2). On the contrary, in the groove section D material in which the groove depth is deeper than the above-mentioned appropriate range, in the case of the test symbol D1 where the welding speed is 30 cm / min, a defective fusion defect occurs in the GMAW part of the low alloy steel. , Test symbol D with a welding speed of 59 cm / min
In No. 2, burn-through (penetration of the welding arc on the back side) occurred at the GMAW welding stage, and it was difficult to perform continuous welding of two layers in one run.

[0043]

As described above, according to the present invention, in butt welding of clad steel, two layers of one run continuous welding can be performed on the high alloy steel side even with the X groove, and welding efficiency can be greatly improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a view showing a groove shape of clad steel.

FIG. 2 is a diagram showing a welding process of the present invention.

FIG. 3 is a diagram showing an outline of a welding device for an inner laminated material of a clad steel pipe according to the present invention.

FIG. 4 shows a welding wire arrangement according to the present invention.

FIG. 5 is a diagram showing a groove shape used in Examples.

FIG. 6 is a schematic diagram showing a welding method of a UOE clad steel pipe according to a conventional method.

[Explanation of symbols]

 1 carbon steel 2 high alloy steel 3 groove on high alloy steel side 4 groove on carbon steel side 5 GMAW bead on carbon steel groove on high alloy steel side 6 latent arc welding bead on high alloy steel groove 7 carbon Steel side latent arc welding bead 8 Welding tip of leading electrode 9 Welding power source of leading electrode 10 Wire feeding mechanism of leading electrode 11, 12 Welding wire of leading electrode 13 Welding tip of trailing electrode 14 Welding power source of trailing electrode 15 Wire feeding mechanism of trailing electrode 16 Welding wire of trailing electrode 17 Weld pool

Claims (4)

[Claims] 1. When butt welding a clad steel obtained by layering a high alloy steel on a carbon steel, the width is 10 to 1 on the high alloy steel side.
2 mm, the depth from the surface of the high alloy steel is provided with a groove consisting of the total of the high alloy steel thickness and the carbon steel thickness of 45 ± 5%,
The root face thickness is 20 ± 5% of the carbon steel thickness, and the depth is the remainder of the carbon steel thickness, and the angle is 70 to 1 on the carbon steel side.
For an X-shaped groove with an angle of 20 °, a carbon steel groove on the high alloy steel side is welded by a GMAW (gas shield arc welding) method using a carbon steel wire, and the remaining high alloy steel groove Part is made of high alloy steel wire and subjected to submerged arc welding by one run continuous welding,
Thereafter, a butt welding method for clad steel, characterized in that the groove portion on the carbon steel side is subjected to latent arc welding with a carbon steel wire. 2. GMAW of carbon steel groove on high alloy steel side
Uses a solid or cored wire with a diameter of 0.9 to 1.6 mm, welding current: 200 to 350 A, welding voltage: 26 to 38
The butt welding method for clad steel according to claim 1, wherein the butt welding is performed under the respective conditions of V. 3. In the arc welding of the groove of the high alloy steel, two wires connected to one power source are used as leading electrodes, and the distance between the two wires is larger than the groove width of the high alloy steel. 4-8 mm wide and arranged at right angles to the welding line direction. Further, one wire connected to one power source is used as a trailing electrode at the groove center and 5 to 20 m behind the leading electrode.
Place the wire at the position m, and the wire for both the leading electrode and the trailing electrode is 0.9 to 1.6 m.
Use solid or cored wire of m diameter, the condition of the leading electrode is current: 400-600A, voltage: 2
5 to 42 V, the following electrode has a current of 200 to 300 A,
The butt welding method for clad steel according to claim 1 or 2, wherein the voltage is set to 25 to 42 V under each condition. 4. The one-run continuous welding of the GMAW of the carbon steel groove on the high alloy steel side and the latent arc welding of the high alloy steel groove is performed at a welding speed of 30 to 60 cm / min. The butt welding method for clad steel according to any one of claims 1 to 3, wherein the arc welding is performed under the respective conditions of separating the leading electrodes by 300 mm or more.