JPH0852572A - Gas shielded metal-arc welding method - Google Patents

Abstract

PURPOSE:To provide a highly efficient joint excellent in the mechanical proper ties by substantially eliminating the root gap of the groove, setting the wire deviation position at the first pass to the prescribed region, and arranging a surface plate in a groove by the prescribed dimension. CONSTITUTION:The solid wire or flux-cored wire of 1.2-2.0mm in diameter is combined with the shielding gas and a backing plate 3. A groove 4 of V- or Y-shape where the root gap is substantially zero and the surface plate side is open is provided, and a surface plate 5 interposed at the lower half part of the groove at the surface side with the length of 10-25mm is provided. The wire deviation position at the first pass is set in the range of 2-12mm along the groove surface of the second half back surface on the groove of a lower plate 2 to achieve the stringer welding or the weaving welding with the welding current of >=280A. The wire deviation position at the first pass is set to the prescribed region thereby, and the surface plate 5 is arranged in the groove with projection of the prescribed dimension to obtain the joint excellent in the cracking resistance, the bead appearance and shape, the mechanical properties of the weld metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal single-sided gas shielded arc welding method for welding a steel structure in a horizontal direction, and more particularly to a high-efficiency horizontal single-sided magnet welding method.

[0002]

2. Description of the Related Art In conventional horizontal one-sided gas shielded arc welding, the basic working conditions are as follows. A gap of about 5 mm is usually provided in the groove root portion. Mainly 1.2 mm diameter wire is used. Uranami welding of the first layer is usually performed at a low current and a low speed such as a welding current of 200 A and a welding speed of 10 cm / min. The second and subsequent layers are welded at a medium current of about 280A.

[0003]

However, this welding method has the following problems. Since a gap is provided at the groove root portion, the groove cross-sectional area is large. Since a wire having a diameter of 1.2 mm is used at low current and low speed or medium current, it is difficult to obtain a high welding amount. At the actual welding site, the gap between the groove root portions is likely to fluctuate, and when this groove root gap is reduced, weld cracking is likely to occur.

[0004] Due to these drawbacks, there is a drawback that the improvement of welding efficiency is hindered and the soundness of the joint is impaired.

The present invention has been made in view of the above problems, and solves the drawbacks of the prior art relating to welding efficiency, soundness of joints, etc., and has high efficiency and crack resistance, bead appearance shape and weld metal. It is an object of the present invention to provide a horizontal single-sided gas shielded arc welding method that can obtain a joint having excellent mechanical performance.

[0006]

In the gas shielded arc welding method according to the present invention, a horizontal one-sided surface is obtained by combining a solid wire or flux-cored wire having a diameter of 1.2 to 2.0 mm with a shield gas and a backing material. In the gas shielded arc welding method, the root interval is substantially zero.
Then, a V- or Y-shaped groove with an open front side is provided, and a cover material with a length of 10 to 25 mm is provided in the lower half of the groove on the front side, and the wire aiming position of the first pass is lowered. It is characterized in that a range of 2 to 12 mm is set on the plate groove from the back surface of the steel plate to the groove surface, and stringer welding or weaving welding is performed with a welding current of 280 A or more.

[0007]

The inventors of the present application repeated the various experimental studies in order to solve the above-mentioned drawbacks of the prior art, and as a result, achieved the object of the present invention by performing gas shield arc welding under the conditions specified in the claims. I have found what I can achieve.

In the present invention, as an example is shown in FIG. 1, an upper upper plate 1 and a lower lower plate 2 are vertically arranged as materials to be welded, and a V-shaped portion is formed at the abutting end thereof. Alternatively, a Y-shaped groove 4 is provided. The gap (root gap) between the grooves 4 on the back surfaces of the upper plate 1 and the lower plate 2 is substantially 0, and the groove 4 is open on the front surface side of the upper plate 1 and the lower plate 2.
Then, on the back surfaces of the upper plate 1 and the lower plate 2, the backing material 3 is attached to the groove portion.
And the cover member 5 is provided on the surface side of the groove 4 so as to intervene in the lower half of the groove. The protrusion height of the cover member 5 in the groove, that is, the length interposed in the lower half of the groove is 10 to 25 mm.

The reasons for limiting each numerical value in the present invention will be described below. (1) Wire diameter: 1.2 to 2.0 mm Wire diameter is less than 1.2 mm, and since the weight per unit length is small, wire feeding is required when using a commercially available welding power source. Even if the speed is set to the upper limit, a high deposition amount cannot be obtained. Further, since the spread of the arc is small, welding defects such as fusion failure are likely to occur when the target position of the wire is deviated. Further, since the wire has low rigidity, it is easy to cause a feeding failure such as buckling, which also causes a welding defect.

When the wire diameter exceeds 2.0 mm, when a large-diameter wire is used in a commercially available welding power source, the capacity (upper limit of welding current) is small and the wire feeding speed cannot be increased, so that a high welding amount can be obtained. I can't. Further, since the wire has high rigidity, the stability of feeding is lowered, and welding defects such as defective fusion are likely to occur. Therefore, the diameter of the wire is 1.2 to 2.0 mm.

(2) Gap root interval: A groove length of 0 mm is substantially reduced to shorten the welding time, and the management of the root interval is omitted to improve the efficiency of the entire welding work. The distance between the leading routes is 0 mm.

(3) Aiming position of wire in the first pass: lower plate opened
2 to 12 mm along the groove surface from the back of the steel plate
For location the first pass of the wire aim positions that GMA is melted excessively by the arc is less than 2 mm, or undercutting occurs toe of the penetration bead, there is a disadvantage that the molten pool falls melted.

On the other hand, when the target position exceeds 12 mm, the groove is less likely to be melted by the arc, so that a good backside beet is not formed and a crack is generated in some cases.

Therefore, the wire aiming position of the first pass is 2 to 12 mm from the lower surface of the lower plate groove.

(4) 1st pass carrying rod: stringer welding or
In the weaving welding stringer welding, the amount of spatter generated is slightly smaller than in the weaving welding, and the welding apparatus can be made smaller and lighter by omitting the weaver. For this reason, stringer welding (without weaving) is performed when the root gap of the groove is substantially 0 mm or close to it, and when the backside bead with good shape and excellent crack resistance is formed in combination with welding conditions. I do.

On the other hand, if the root interval becomes wide due to poor machining accuracy of the groove and the like, and undercut of the backside bead or melt-through of the molten pool cannot be prevented even in combination with welding conditions, weaving welding is performed.

(5) As a leak preventive material for molten metal,
The materials are arranged as shown in FIG. As shown in FIG. 1, this cover material 5 functions as a leak preventer for the molten metal accumulated in the groove 4. In the welding of the finish layer, it is usually difficult to increase the amount of deposition by a high current and a low speed from the viewpoint of preventing the molten metal from dripping. However, since the present invention uses the cover material 5 as a material for preventing leakage of molten metal, it is possible to perform welding with a high welding amount. In this case, the upper end of the cover member 5 is projected to the lower half of the groove in the range of 10 mm or more and 25 mm or less than the lower end of the groove.

When the amount of protrusion of the front cover material is less than 10 mm, the leakage prevention effect is limited to only the lowermost pass. The protrusion amount is set to 10 mm or more in order to enable welding with a high welding amount even after the next pass.

When the protrusion amount of the surface covering material exceeds 25 mm, the wire aiming position of the lowermost path is out of the proper range due to the interference with the surface covering material, so that defects such as defective fusion or defective bead appearance / shape occur. . Therefore, the amount of protrusion of the cover member is 10 to 25 mm from the lower end of the groove.

(6) Wire chemical component (flux containing flux
Ear and solid wire) C: 0.01 to 0.20% by weight C (carbon) is added for the purpose of forming a good backside bead, preventing the backside welding bead from cracking, adjusting the mechanical performance of the weld metal, etc. To do.

When C is less than 0.01% by weight, the potential gradient in the arc is small, so the welding voltage at the proper arc length becomes low. This reduces the penetration depth, making it difficult to form the back bead. C is an element that enhances the hardenability of the weld metal, but if it is less than 0.01% by weight, the ferrite grains become coarse and cracks are likely to occur in the backside weld bead. Furthermore, the strength and toughness of the weld metal are insufficient with respect to the base metal.

When C exceeds 0.20% by weight, precipitation of an austenite phase having a small solid solubility limit of impurities such as P and S increases, and the impurity concentration at grain boundaries increases. Further, the solidification temperature range of the molten metal is expanded. Due to these influences, the backside weld bead is likely to crack. On the other hand, due to the increase in strength, the toughness of the weld metal becomes insufficient with respect to the base metal. Further, CO is likely to be generated in the droplet or the molten pool. The CO in the droplet explodes to generate a large amount of spatter, and the CO in the melted place causes pore defects such as blowholes or pits. Therefore, the amount of C in the wire is 0.01 to 0.2.
0% by weight.

Si: 0.20 to 1.50 wt% Si (silicon) is added for the purpose of forming good backside beads, preventing the occurrence of pore defects, and adjusting the mechanical performance of the weld metal.

If the Si content is less than 0.01% by weight, the familiarity of the bead with the base material is deteriorated, and in particular, the shape defect of the back bead occurs. Further, if the amount of the other deoxidizer added is insufficient, pore defects are likely to occur. Furthermore, the strength of the weld metal is insufficient with respect to the base metal.

When Si exceeds 1.50% by weight, the strength of the weld metal becomes excessive and the toughness becomes insufficient with respect to the base metal. Therefore, the amount of Si in the wire is 0.20 to 1.50.
Weight%

Mn: 0.20 to 2.50 wt% Mn (manganese) is added for the purpose of preventing cracks in the backside weld bead, preventing pore defects, and adjusting the mechanical performance of the weld metal.

Like C, Mn enhances the hardenability of the weld metal and forms impurities S and MnS. But,
If the Mn content is less than 0.20% by weight, these effects are insufficient, the ferrite grains are coarsened, and the S content in the final solidification zone does not decrease. Become. Further, if the amount of the other deoxidizer added is insufficient, pore defects are likely to occur. Furthermore, the strength and toughness of the weld metal are insufficient with respect to the base metal.

When the Mn content exceeds 2.50% by weight,
The strength of the weld metal becomes excessive and the toughness becomes insufficient with respect to the base metal. Therefore, the amount of Mn in the wire is 0.20 to 2.50% by weight.

Ti: 0.01 to 0.50 wt% Ti (titanium) is added for the purpose of forming a favorable backside bead, preventing the occurrence of pore defects, and adjusting the mechanical performance of the weld metal.

When the Ti content is less than 0.01% by weight, deoxidation is insufficient and the oxygen content of the droplets is high, so the surface tension is reduced and the shape is elongated, causing irregular short circuit with the molten pool. To increase. This makes the shape of the molten pool or the convection of the molten metal unstable. Further, since the arc disappears when a short circuit occurs, the temperature of the molten pool or the heat input amount decreases. These effects make it difficult to form a good back bead.

If the amount of Ti exceeds 0.50% by weight, the hard slag covers the entire surface of the bead, and the weldability such as slag removal or continuous welding deteriorates. Further, the strength of the weld metal becomes excessive, and the toughness becomes insufficient with respect to the base metal. Therefore, the amount of Ti in the wire is 0.01 to 0.50% by weight.

Na, K, Ce compounds: Na, K, Ce
In the case of flux-cored wire: 0.005 to 0.35% by weight In the case of solid wire: 0.00002 to 0.00
The 3 wt% Na, K, Ce compound is added for the purpose of stabilizing the arc and droplet transfer.

For solid wires, these compounds are added by coating the surface of the wire as needed.

(A) Flux-cored wire: 0.005
0.35 wt% If less than 0.005 wt%, the arc and droplet transfer are unstable, which also reduces the stability of the molten pool. For this reason, the shape defect of the backside bead becomes remarkable. Also,
Increase of spatter generation or deterioration of bead appearance / shape occurs.

If the content exceeds 0.35% by weight, Na, K, C
Since the vapor pressure of the e compound is high, the vapor pressure in the arc increases excessively. As a result, the arc force decreases and the penetration shape becomes unstable and shallow, so the shape of the back bead deteriorates. Also, since the droplet size to be transferred becomes large,
A large amount of large spatters are generated.

Therefore, Na in the flux-cored wire,
The addition amount of the K and Ce compounds is 0.005 to 0.35% by weight in terms of Na, K and Ce.

(B) Solid wire: 0.00002-
0.003 wt% When adding a Na, K, Ce compound to a solid wire, the compound is mainly applied to the wire surface. Usually, since the arc is generated from the wire surface, the Na, K, Ce compound applied to the surface effectively acts to stabilize the arc.

If it is less than 0.00002% by weight, the remarkable effect of stabilizing the arc and droplet transfer cannot be obtained.

If it exceeds 0.003% by weight, the amount of adhesion on the surface of the wire increases, so that they are deposited in the wire feeding path and the wire feeding property is deteriorated. Therefore, the addition amount of Na, K and Ce compounds to the solid wire is N
The total amount of a, K, and Ce is set to 0.00002 to 0.003% by weight, and is applied to the wire surface as necessary.

Al, Mg: 0.05 to 1.00 in total
Weight% Al and Mg are added as needed for the purpose of reducing the oxygen content of the weld metal and improving the toughness. In addition, the addition of Mg to the solid wire is
Alternatively, it is carried out by applying a powder of a Mg compound and then applying Cu plating on the powder to cover it.

When Al and / or Mg is less than 0.05% by weight, no remarkable effect is observed in improving the toughness of the weld metal.

When Al and / or Mg exceeds 1.00% by weight, the vapor pressures of Al and Mg are high and the vapor pressure in the arc increases excessively. As a result, the amount of fumes generated increases and the size of the droplets to be transferred increases, so that a large amount of spatter is generated and workability deteriorates. Therefore,
The total amount of Al and Mg in the wire is 0.05 to 1.
It is set to 00% by weight.

Ni: 0.10 to 4.00 wt% Ni is added as necessary for the purpose of increasing the amount of austenite in the weld metal and improving toughness.

If the Ni content is less than 0.10% by weight, no remarkable effect is observed in improving the toughness of the weld metal. Ni is 4.0
If it exceeds 0% by weight, the solid solubility limit of impurities such as P and S becomes small like C, so that the precipitation of austenite phase increases and the impurity concentration of grain boundaries increases. Also, low melting point Ni
S is formed. Due to these influences, the backside weld bead is likely to crack. Therefore, N in the wire
The i amount is 0.10 to 4.00% by weight.

(7) Chemical composition of surface coating material (molten metal leak preventive material) Adjusting the fire resistance of solid matter, viscosity of slag, surface tension, fluidity, etc. to adjust the bead appearance and shape, and Si is used for the purpose of improving the slag removability.
A refractory material containing an appropriate amount of O ₂ , Al ₂ O ₃ , CaO, MgO, ZrO ₂ or the like is used for molding. The contents of these chemical components are as follows.

SiO ₂ : 30.0 to 60.0% by weight When SiO ₂ is less than 30.0% by weight, the refractory property of the solid matter is insufficient and the melting amount becomes large, so that the surplus of the finishing bead becomes excessive. . As a result, the bead shape is deteriorated, and the remaining amount of the groove cross-sectional area is increased to reduce the welding efficiency.

If the SiO ₂ content exceeds 60.0% by weight, the fluidity of the slag becomes excessive, defects such as undercut or slag entrainment occur, and the appearance and shape of the bead become uneven. Therefore, the amount of SiO ₂ in the refractory is 30.0
To 60.0% by weight.

Al ₂ O ₃ : 5.0 to 40.0% by weight When Al ₂ O ₃ is less than 5.0% by weight, the fire resistance of solids is insufficient as in the case of SiO _2. Is too large. As a result, the bead shape is deteriorated, and the remaining amount of the groove cross-sectional area is increased to reduce the welding efficiency.

When Al ₂ O ₃ exceeds 40.0% by weight, the fire resistance becomes excessive and the surplus of the finishing bead becomes small.
In this case, an overlap occurs at the boundary with the portion where the cover material does not work. Therefore, Al ₂ 0 ₃ content in the refractory is 5.0
To 40.0% by weight.

CaO: 0.01 to 40.0% by weight If CaO is less than 0.01% by weight, SiO ₂ , Al ₂ O ₃
Similarly, the fire resistance of solids is insufficient, and the excess of finishing beads is excessive. As a result, the bead shape is deteriorated, the remaining amount of the groove cross-sectional area is increased, and the welding efficiency is reduced. Further, the surface tension of the slag is increased and the covering is deteriorated, so that the bead appearance is deteriorated.

If CaO exceeds 40.0% by weight, Al
Similar to ₂ O ₃ , the fire resistance becomes excessive and the surplus of the finishing bead becomes small, so that an overlap occurs at the boundary with the portion where the cover material does not work. Therefore, the amount of CaO in the refractory is 0.01 to 40.0% by weight.

MgO: 0.01 to 20.0% by weight If MgO is less than 0.01% by weight, SiO ₂ , Al
_{As with 2} O ₃ and MgO, the solid materials lack fire resistance, so
Excessive amount of finishing beads. As a result, the bead shape is deteriorated, and the remaining amount of the groove cross-sectional area is increased to reduce the welding efficiency. Also, the slag removability deteriorates.

On the other hand, when the content of MgO exceeds 20.0% by weight, the fire resistance becomes excessive as is the case with Al ₂ O ₃ and CaO, and the extra amount of the finishing bead becomes small, so that the portion with which the surface coating material does not work is formed. Overlap occurs at the boundary. Therefore, the amount of MgO in the refractory is 0.01 wt% or more and 20.0 wt% or more.
Below.

ZrO ₂ : 0.01 to 20.0% by weight ZrO ₂ adjusts the fire resistance of solids and optimizes the extra size of the finishing bead like SiO ₂ , Al ₂ O ₃ , MgO and MgO. . The excess is too large when ZrO ₂ is less than 0.01% by weight and too small when it exceeds 20.0% by weight. Therefore, the amount of ZrO ₂ in the refractory is 0.01 to 20.0% by weight.

[0055]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Table 1 below shows welding conditions.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

[0059]

[Table 4]

Table 5 below shows the chemical composition of the refractory which constitutes the table material.

[0061]

[Table 5]

[0062]

[Table 6]

[0063]

[Table 7]

[0064]

[Table 8] See Table 6 for the welding conditions for the first layer.

[0065]

[Table 9] See Table 7 for welding conditions.

As shown in Table 8, in the examples satisfying the conditions of the present invention, the arc stability, the appearance shape of the back bead, the spatter generation amount, and the
All of the crack resistance was excellent. On the other hand, in the case of the comparative example which is out of the condition of the present invention, any of these performances was inferior.

As is clear from Table 9, the plate thickness is 1
Even in the case of welding a 6 mm welded material, in the case of an example satisfying the conditions of the present invention, arc stability, bead appearance shape, spatter generation amount, crack resistance of the first layer, mechanical properties of weld metal All the performances of were excellent. On the other hand, in the case of the comparative example which deviates from the conditions of the present invention, the performance of any of these was inferior.

[0068]

As described above, according to the present invention,
The groove root interval is set to substantially 0, the wire aiming position of the first pass is set to a predetermined area, and the cover material is arranged so as to project in the groove with a predetermined dimension. Therefore, horizontal one-sided gas shield arc welding is performed. With high efficiency, crack resistance, bead appearance
A joint excellent in shape and mechanical performance of weld metal can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of the present invention.

FIG. 2 is a diagram showing welding conditions.

FIG. 3 is a diagram showing welding conditions.

[Explanation of symbols]

 1: Upper plate 2: Lower plate 3: Backing material 4: Groove 5: Front material

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C22C 38/00 301 Y 38/14 (72) Inventor Susumu Imaoka Fujisawa-shi, Kanagawa 100 No. 1 Urakawachi Urakawachi Ceremony Company Kobe Steel Fujisawa Office

Claims (6)

[Claims] 1. A horizontal one-sided gas shielded arc welding method in which a solid wire or a flux-cored wire having a diameter of 1.2 to 2.0 mm is combined with a shield gas and a backing material, and a root interval is substantially zero. , A V- or Y-shaped groove with an open front side is provided, and an intervening front cover material with a length of 10 to 25 mm is provided on the lower half of the groove on the front side, and the wire target position of the first pass is the lower plate. Set on the groove from the back surface of the steel plate along the groove surface to a range of 2 to 12 mm, and
A gas shielded arc welding method comprising performing stringer welding or weaving welding with a welding current of 80 A or more. 2. The flux-cored wire, based on the total weight of the wire, is C: 0.01 to 0.20% by weight, and Si:
0.20 to 1.50% by weight, Mn: 0.20 to 2.50
% By weight, Ti: 0.01 to 0.50% by weight, Na, K,
Ce compound: 0.00 in total when converted to Na, K, Ce
The gas shielded arc welding method according to claim 1, which contains 5 to 0.35% by weight. 3. The solid wire comprises C: 0.01 to 0.20 wt% and Si: 0.20 with respect to the total weight of the wire.
~ 1.50% by weight, Mn: 0.20 to 2.50% by weight,
Ti: 0.01 to 0.50% by weight, balance Fe
The gas shielded arc welding method according to claim 1, wherein the gas shielded arc welding method has a composition including an unavoidable impurity. 4. The flux-cored wire, C: 0.01 to 0.20% by weight, Si:
0.20 to 1.50% by weight, Mn: 0.20 to 2.50
% By weight, Ti: 0.01 to 0.50% by weight, Na, K,
Ce compound: 0.00 in total when converted to Na, K, Ce
5 to 0.35 wt%, Al, Mg: 0.05 to 1.00 wt% in total, Ni: 0.10 to 4.
The gas shielded arc welding method according to claim 1, which contains 100% by weight of one kind or two kinds. 5. The solid wire comprises C: 0.01 to 0.20 wt% and Si: 0.20 with respect to the total weight of the wire.
~ 1.50% by weight, Mn: 0.20 to 2.50% by weight,
Ti: 0.01 to 0.50 wt%, Na, K, Ce compound: 0.00002 in total when converted to Na, K, Ce
In addition to containing 0.003% by weight, Al and Mg: 0.05 to 1.00% by weight in total, Ni: 0.10 to 4.0
The gas shielded arc welding method according to claim 1, characterized in that it contains 0% by weight of one or two kinds, and the balance thereof is Fe and inevitable impurities. 6. The cover material is SiO ₂ : 30.0-6.
0.0 wt%, Al ₂ O ₃ : 5.0-40.0 wt%, C
aO: 0.01 to 40.0 weight, MgO: 0.01 to 2
The gas shielded arc welding method according to claim 1, wherein the refractory material has a composition of 0.0 wt% and ZrO ₂ : 0.01 to 20.0 wt%. .