JPH0899179A - Submerged arc welding method for one side surface - Google Patents

Abstract

PURPOSE: To prevent the development of a large quantity of fume and malodor and obtain sound penetration bead at the same time of obtaining good welding work environment, in a submerged arc welding method for one side surface by using a steel plate and flux as the backing material. CONSTITUTION: The sheet-like solid flux having 2-6mm thickness is laid on the steel plate and further, on the upper layer of the solid flux, a cloth-like or mat-like glass fiber having 1.0-4.0mm thickness is laid. A copper plate is pushed to the material to be welded while interposing these glass fiber and solid flux and the backing material is brought into close contact with the back surface of the material to be welded, and the welding is executed from the front surface side. The glass fiber contains 50-75% SiO2 , 5-25% Al2 O3 , 10-30% CaO and the solid flux contains >=60% SiO2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a backing flux suitable for obtaining a sound back bead free from defects such as undercut in single-sided submerged arc welding using a copper plate and a flux as a backing material. The present invention relates to a single-sided submerged arc welding method in which odor and fumes generated from a backing flux are reduced as much as possible.

[0002]

2. Description of the Related Art The one-sided submerged arc welding method can finish a thick plate from one side only once.
Since it is an extremely highly efficient welding method, it has recently been generally applied to welding of many structures including welding of plate joints in shipbuilding.

However, since the one-sided welding forms the back bead by welding from the front side, if an improper backing material is used, a defect occurs in the back bead, and it takes time to repair it, resulting in high efficiency. The welding method also reduces the effect by half.

In single-sided submerged arc welding using a copper plate and a flux as a backing, since a copper plate is used as the backing, a high current can be used and a particularly efficient one-sided welding method, but an undercut occurs on the back bead. It has the drawback of being easy to do. Various studies have been conducted in the past for the purpose of preventing this, and as a result, it has been found that the use of a solid backing flux can greatly improve. However, the solid flux has poor adhesion to the steel sheet, and there are problems that casting burrs are generated on the back bead, and the back bead burns out. Therefore, until the backing flux is adhered to the back surface of the steel sheet, a backing flux containing a thermosetting binder is generally used so that the backing flux becomes solid when forming the back bead in powder or granular form. It is used.

[0005]

The undercut of the back bead, which was a major problem in single-sided submerged arc welding using a copper plate and a flux as a backing, has already been solved by the prior art. However, an organic thermosetting resin is used as the thermosetting binder that functions to solidify the flux by welding heat, and this is thermally decomposed during welding, and a large amount of fumes and odor are generated. This not only deteriorates the welding work environment, but also adversely affects the human body depending on the type and amount.

The present invention has been made in view of the above problems, and prevents a large amount of fumes and malodor during welding, which are problems of the conventional single-sided submerged arc welding method using a steel sheet and a flux as a backing material. However, it is an object of the present invention to provide a single-sided submerged arc welding method capable of producing a good welding work environment and at the same time obtaining a sound back bead.

[0007]

A single-sided submerged arc welding method according to the present invention is a single-sided submerged arc welding method in which a copper plate and a flux are used as a backing material, and a sheet shape having a thickness of 2 to 6 mm is formed on the copper plate. Of solid flux of 1.0 to 4.
Place 0mm thick cloth or matte glass fiber,
The glass plate and the solid flux are sandwiched between them to press a copper plate against the material to be welded to bring the backing material into close contact with the back surface of the material to be welded, and welding is performed from the front side.

[0008]

The present inventors have obtained the following findings as a result of repeating various experimental studies in order to solve the above-mentioned problems of the prior art. In order to obtain a back bead without undercut, it is necessary that the backing flux be in the solid state during the period after the molten pool on the back side is formed and then it is solidified to form the back bead. Is. However, as the thermosetting binder that functions to harden the flux by welding heat, other than the organic thermosetting resin, the effect is small. In addition, as a result of studying the flux that has been solidified in advance, the solid flux alone cannot secure the adhesion to the back surface of the steel sheet. Therefore, as a result of further various studies, a sheet-like solid flux having a thickness of 2 to 6 mm was placed on the steel plate, the shape and height of the back bead were stabilized at this portion, and 1. 0 to
By placing a 4.0mm glass fiber, it is possible to ensure the adhesion to the steel sheet, it is possible to obtain a familiar good penetration bead can not undercut, further SiO _2: 5
_{0~75%, Al 2 O 3:} 5~25%, CaO: 10~3
With glass fibers containing 0%, a shiny, slag-free back bead is obtained. If a solid flux containing 60% or more of SiO ₂ is used, a back bead having a more stable height can be obtained.

Next, the reasons for limitation in the above-mentioned constituent features of the present invention will be described.

Solid Flux Since the solid flux plays a role of stabilizing the shape and height of the back bead as described above, S having a high degree of fire resistance is used.
It is preferable to use a material containing iO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ or the like as a main component, but among them, if one containing 60% or more of SiO ₂ that is the same component system as the upper glass fiber is used, The shape and height of the back bead are more stable. S
When iO ₂ exceeds 70%, the result is slightly different depending on the combination of other components, but the height of the back bead tends to be somewhat unstable.

The method of molding the solid flux is not particularly limited, but the raw material is put into a mold and fired at a high temperature to form a ceramic, or water glass or the like is used as an inorganic adhesive and dried. It may be molded. Further, commercially available refractories and the like can also be used.

Although the size is not particularly limited, it is safer that the width of the solid flux is 50 mm or more in consideration of bending and displacement of the welded joint. Further, the length of the solid flux may be appropriately selected according to the usability, but is 150 when considering the ease of handling.
About 600 mm is preferable.

The thickness of the solid flux is a major factor affecting the stability of the back bead. If the thickness is less than 2 mm, the arc directly blows to the lower copper plate even if the thickness of the upper glass fiber is controlled. The copper plate may be damaged or slag may be burned on the copper plate, so it is necessary to avoid it. Also, if the thickness exceeds 6 m, the back bead height becomes unstable even if the composition of the flux is taken into consideration, so the thickness is 6 m.
It must be m or less.

The glass fiber used for the upper layer of the glass fiber solid flux is not particularly limited and may be cloth-like or mat-like, and may have a certain degree of flexibility and shrinkability, but the composition is particularly SiO.
_{2: 50~75%, Al 2 O} 3: 5~25%, CaO: 1
With glass fibers containing 0 to 30%, a shiny, slag-free back bead is obtained. However,
The thickness of the glass fiber is an important factor for the stability of the back bead, and if it is less than 1.0 mm, the adhesion to the steel plate cannot be secured even if a highly flexible one is used, and the back bead has a casting burr. The thickness of the glass fiber needs to be 1.0 m or more, since this may cause burnout or burn through when a large current is used. On the contrary, when the thickness of the glass fiber exceeds 4 mm,
A solid bead having a high degree of refractory is used as a lower layer to increase the back bead height and make it unstable. Therefore, the thickness of the glass fiber is 4 mm or less.

[0015]

EXAMPLES Next, examples of the present invention will be described in comparison with comparative examples.

The steel sheets shown in Table 1 below, the welding wires shown in Table 2 below, and the flux shown in Table 3 below were used to weld under the groove shapes and welding conditions shown in Table 4 below.
The components of the glass fibers used in the experiment are shown in Table 5 below, the type of backing material is shown in Table 6, and the welding test results are shown in Table 7 below.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3] _{Other; CO 2, B 2 O 3} , Fe-Si, Fe-Mn , etc.

[0020]

[Table 4]

[0021]

[Table 5] Others are B ₂ O ₃ , MgO, K ₂ O and the like.

[0022]

[Table 6]

[0023]

[Table 7] * 1 There is seizure on the copper plate

As shown in Table 7, in Examples 1 to 6 satisfying all the requirements of the present invention, no defect was generated and a good back bead was obtained. In addition, there was almost no generation of foul odor fumes, which was a problem of conventional backing flux, and a good welding work environment was obtained.

On the other hand, in Comparative Example 7, the conventional backing flux was used, and although a good back bead was obtained, a lot of foul odors or fumes were generated. In Comparative Example 8, since the thickness of the glass fiber was smaller than the lower limit of the present invention, poor adhesion of the backing material to the back surface of the steel sheet occurred, and flashing occurred on the back bead. In Comparative Example 9, the thickness of the glass fiber exceeded the upper limit of the present invention, so the height of the back bead was high and it became unstable. In Comparative Example 10, since the thickness of the solid flux was less than the lower limit, the back bead was burned on a part of the copper plate.
In Comparative Example 11, the thickness of the solid flux exceeded the condition of the present invention, the height of the back bead was high, and it became unstable.

[0026]

As described above, according to the single-sided submerged arc welding method of the present invention, it is possible to prevent generation of fumes and bad odor during welding, and it is possible to obtain a good working environment and a sound back bead. .

Claims (3)

[Claims] 1. A single-sided submerged arc welding method using a copper plate and a flux as a backing material, wherein a sheet-like solid flux having a thickness of 2 to 6 mm is placed on the copper plate,
Further, cloth-like or mat-like glass fibers having a thickness of 1.0 to 4.0 mm are placed on the upper layer of the solid flux, and the copper plate is pressed against the material to be welded with the glass fibers and the solid flux sandwiched therebetween. Stick the backing material to the back surface of the material to be welded,
A single-sided submerged arc welding method characterized in that welding is performed from the front side. 2. The glass fiber is SiO ₂ : 50-7.
The single-sided submerged arc welding method according to claim 1, which contains 5%, Al ₂ O ₃ : 5 to 25%, and CaO: 10 to 30%. 3. The solid flux contains 60% of SiO _2.
The one-sided submerged arc welding method according to claim 1, comprising the above.