JP2000271788A - Bevel filling material for simple one side surface submerged arc welding and welding method using this material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bevel filling material which has good welding workability and crack resistance and obtains the welded part having good low temp. ductility in a simple one side surface submerged arc welding for a steel used in the low temp., and a welding method using this bevel filling material. SOLUTION: In the bevel filling material for simple one side surface submerged arc welding, this material is contained by wt.% of <=0.07% C, <=0.05% Si, 0.6-1.5% Mn, <=0.015% P, <=0.01% S, 2.4-3.4% Ni, >0.03-0.4%; Al, <=0.005% N and has 4-6 bulk sp.gr. Further, the simple one side surface submerged arc welding method is executed by filling the bevel filling material and a bond flux having a prescribed component into the bevel and welding with a welding wire having a prescribed component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a so-called simple single-sided submerged arc welding mainly used in the field of shipbuilding. Simple single-sided submerged arc welding is single-sided welding using a backing material containing a solid refractory oxide as a main component,
The present invention relates to a groove filler used for this and a welding method using the same. More specifically, a groove filler used for simple single-sided submerged arc welding, which can provide a weld metal excellent in strength and low-temperature toughness at the time of single-sided single-layer welding for low-temperature steel used for an upper deck of an LPG ship and the like. The present invention relates to a low-temperature steel welding method using the same. The term “low-temperature steel” used here means JIS used for shipbuilding.
SLA325, SLA360 steel, etc. specified as “carbon steel sheet for low-temperature pressure vessels” in G3126 and the like, and have a strength equivalent to these, and have a Charpy test temperature of −40 to −60.
A steel material that satisfies toughness at ℃.

[0002]

2. Description of the Related Art Conventionally, single-sided submerged arc welding, which is excellent in welding efficiency, is generally used for welding thick steel plates for shipbuilding and the like, but the heat input is large, and the toughness of a weld tends to deteriorate. . Therefore, especially in the welding of low-temperature steels such as LPG ships, which have strict requirements for low-temperature toughness, in order to satisfy the low-temperature toughness of the welded portion, the welding heat input must be restricted to about 9 kJ / mm or less, and is applicable. The board thickness is about 16m
m or less.

However, in recent years, from the viewpoint of material development, the toughness of the heat-affected zone of the base metal when the low-temperature thick steel plate is subjected to single-sided submerged arc welding on the LPG ship or the like has been improved.
It is now possible to weld low-temperature thick steel plates up to mm. These low-temperature steels for single-sided submerged arc welding include, for example, TMCP (Thermo Mechani).
Cal Control Process technology has been put to practical use in which the low-temperature toughness of the heat-affected zone of the base material is improved by reducing the carbon equivalent and controlling the oxide using Ti deoxidation or composite deoxidation of Al and Ti.

[0004] As a single-sided submerged arc welding method generally used for large plate joint welding having a length of 20 m for shipbuilding or the like, a flux copper backing single-sided submerged arc welding method and a simple single-sided submerged arc welding method are used. The former uses a special device, sprinkles the granular back flux on the backing copper plate, places the steel plate to be welded on top of it, fills the groove route with the front flux and inserts the welding wire. This method is used for welding. In addition, the latter has SiO on a backing material containing a solid refractory oxide as a main component.
_In the state where about 4 to 8 glass tapes of which ₂ is the main component are arranged and they are in contact with the back side of the groove of the steel plate to be welded, when the front flux and the root gap of the groove are large, the opening of the steel grain is performed. This is a method in which a pre-filling material is filled and welding is performed using a welding wire.

Conventionally, as a groove filler used in the single-sided submerged arc welding method, for example, Japanese Utility Model Publication No.
No.-332 and JP-A-60-46895. However, the groove filler disclosed in Japanese Utility Model Publication No. 43-332 can be applied to mild steel and HT490 but cannot be applied to welding of low-temperature steel such as LPG ships that require low-temperature toughness of -60 ° C. It is. Also,
Japanese Patent Application Laid-Open No. Sho 60-46895 discloses a groove for single-sided subarc welding of low-temperature steel containing Pb or Bi for the purpose of improving slag peeling of a back bead when a glass tape-based backing material is used. Fillers have been proposed. However, in the single-sided submerged arc welding method where cooling from the backing material is fast,
The inclusion of these low-melting components is not preferred for the occurrence of hot cracking.

The present inventors have also disclosed in Japanese Patent Application Laid-Open No. 10-263.
No. 881, Japanese Patent Application Laid-open No. 881/1999 discloses that as a groove filler for single-sided submerged arc welding of low-temperature steel, C, Si, Mn, Ni,
A grooved steel filler with Al, N, and O specified and a particle diameter of 45 μm to 180 μm was proposed. However, as a result of repeated examinations, it can be applied to the flux copper backing single-sided submerged arc welding method among the single-sided submerged arc welding methods, but the holding force of the backing material is lower than this method, and the cooling rate However, it was found that it was difficult to control the back bead shape on the back surface of the groove and secure low-temperature toughness by the simple single-sided submerged arc welding method, which is slow.

[0007] The simple single-sided submerged arc welding method can be easily carried out at an assembly site such as a shipbuilding, compared with the flux copper backing single-sided submerged arc welding method using a fixed device. There is a demand for the development of a welding method for low-temperature steel using steel.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, the present invention provides good single-sided submerged arc welding of low-temperature steel and good welding workability together with a weld metal excellent in low-temperature toughness. An object of the present invention is to provide a groove filler and a welding method using the same.

[0009]

Means for Solving the Problems The inventors of the present invention have studied variously to achieve the above object, and have found that a groove filler capable of obtaining a good back bead shape and a low-temperature toughness can be obtained. The inventors have found a welding method using a welding wire and a bond flux of a specific component, and have completed the present invention. The gist of the invention is as follows.

(1) In a simple one-sided submerged arc welding groove filler, in terms of% by weight, C: 0.07% or less, S
i: 0.05% or less, Mn: 0.6 to 1.5%, Ni:
2.4-3.4%, Al: 0.002-0.4%, P: 0.015% or less, S: 0.01% or less, N:
A steel grain with 0.005% or less and a bulk specific gravity of 4 to
6. A groove filler for simple single-sided submerged arc welding, characterized in that: (2) The groove filler for simple single-sided submerged arc welding according to (1), wherein the Al content of the steel grain is more than 0.03 to 0.4%. The groove filler for simple single-sided submerged arc welding according to (1) or (2), which has a length of 2 mm or less.

(4) A refractory acid is applied to the back of the groove of the steel plate for low temperature use.
A backing material mainly composed of
The simple single-sided submerged arc welding method
Groove filling according to any one of (1) to (3)
Material, and in weight%, SiO ₂: 10-20%, Mg
O: 20-33%, Al₂O₃: 13-25%, TiO
₂: 5 to 15%, CaF₂: 6-12%, CaCO₃:
5-8%, B₂O₃: Containing 0.2 to 0.5%, and
Bond having a Bn defined by the following formula of 0.8 to 1.5:
LUX and weight%, C: 0.01-0.1%, S
i: 0.05% or less, Mn: 0.6 to 1.6%, Ni:
2.4 to 3.4%, Al: 0.002 to 0.5%
P: 0.015% or less, S: 0.010% or less,
N: 0.005% or less, and the wire diameter is 4.4 to
Using a 6.6 mm steel welding wire,
Welding with a root gap of 6 mm or less
Simple one-sided submerged arc welding method for low temperature steel
Law. Bn = (0.108 [CaO] +0.068 [MnO]
+0.10 [MgO]) / (0.105 [SiO₂] +
0.002 [Al₂O₃])

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION
Based on the groove filler for single-sided submerged arc welding of low-temperature steel proposed in Japanese Patent No. 3881, the back bead shape and mechanical properties of the weld metal during simple single-sided submerged arc welding were investigated in more detail. As a result, it was found that there was a large difference in the back bead forming ability and the component design of the weld metal between the simple single-sided submerged arc welding method and the flux copper backing single-sided submerged arc welding method due to the difference in the backing method.

In general, simple single-sided welding uses, as a backing material, a plate mainly made of powder containing a refractory oxide made of water glass, on which 4 to 8 glass tapes mainly composed of SiO2 are placed. They are welded by contacting them to the back surface of the groove of the steel plate to be welded. On the other hand, in the flux copper backing single-sided submerged arc welding method, the backing copper plate is arranged as a fixed device, and the steel plate to be welded is welded via the granular back flux scattered thereon. For this reason,
In the flux copper backing single-sided submerged arc welding method, the height of the back bead generated in the back flux is limited by the copper plate because the backside of the groove is held by the backing copper plate even when welding with a relatively large current. Be regulated. On the other hand, simple single-sided submerged arc welding holds the groove backside with a backing material mainly composed of a refractory oxide and a glass tape having a low fire resistance compared to the copper plate, so the back bead is made of glass. Produced in the tape and backing material, the holding power of the back bead is very small, and it is difficult to control the height of the back bead to prevent poor welding.

The backing material mainly composed of a refractory oxide used in the simple single-sided submerged arc welding method has a cooling effect of the weld metal as compared with the backing copper plate used in the flux copper backing single-sided submerged arc welding method. Since it is small, the strength and toughness of the weld metal are greatly deteriorated. From the above experimental results of the inventors, when welding low-temperature steel using simple single-sided submerged arc welding, compared to welding using flux copper backing single-sided submerged arc welding method,
It was found that stricter control of welding conditions was necessary.

[0015] The inventors of the present invention have investigated and studied in detail the welding conditions when welding low-temperature steel using simple one-sided submerged arc welding. As a result, compared to the flux copper backing single-sided submerged arc welding method, it was found that the following measures must be taken in simple single-sided submerged arc welding, in which the height of the back bead is more difficult to control and the cooling capacity of the weld metal is small. Was. That is, while ensuring toughness due to solid solution of the Ni matrix in the components in the groove filler, increasing the amount of Al controls oxides in the weld metal and adjusts the amount of oxygen to produce ferrite and refine the structure. It was found that by improving the low-temperature toughness without excessively increasing the strength, and by specifying the bulk specific gravity of the groove filler, a good back bead shape without the problem of poor welding can be obtained. . In the present invention, good toughness can be secured at -40 to -60 ° C by filling the above-mentioned filler and bond flux of a predetermined component into a groove, and welding low-temperature steel with a welding wire of a predetermined component. A simple one-sided submerged arc welding with a weld metal obtained and excellent welding workability such as a back bead shape is possible.

The details of the present invention will be described below. The groove filler of the present invention has a low C content as its basic component,
It contains Ni and Al in predetermined amounts and further defines Si, Mn, and N, whereby good toughness can be obtained at a low temperature. Further, since Ni is high, P and S are limited from the viewpoint of resistance to hot cracking. Further, the bulk specific gravity of the groove filler was specified so that a good back bead could be obtained when the groove was filled and welded. Also, in the present invention, when the low-temperature steel is subjected to simple single-sided submerged arc welding using the groove filler, in order to obtain good low-temperature toughness and good welding workability of the weld metal, the groove filling is performed. In addition to the material, the composition of the wire is regulated for the same reason, and the basicity: Bn of the bond flux is regulated.

First, the reasons for limiting the component composition of the groove filler of the present invention will be described. C needs to be 0.07% or less. C must be set low to obtain good toughness. In order to obtain good low-temperature toughness with the weld metal, the C content of the weld metal must be reduced to about 0.1% or less, and the steel sheet is 0.12% or less. The C content of the pre-filler was set to 0.07% or less.

The content of Si must be 0.05% or less. Si is useful as a deoxidizing element, but 0.05%
If the ratio exceeds the limit, the toughness of the weld metal deteriorates, so the upper limit was made 0.05%.

Mn needs to be 0.6 to 1.5%. Mn is necessary for securing the hardenability of the weld metal and generating transformation nuclei for intragranular ferrite. Such an effect of Mn can be obtained at 0.6% or more, but 1.5% or more.
If it exceeds, the hardenability of the weld metal becomes excessive and the toughness deteriorates.

Ni needs to be 2.4 to 3.4%. Ni forms a solid solution in the matrix of the weld metal to increase the toughness of the ferrite itself. Such an effect of Ni can be obtained at 2.4% or more in the present weld metal. on the other hand,
If it exceeds 3.4%, P and S are likely to precipitate at the grain boundaries,
Since high temperature cracking is likely to occur, the upper limit is set to 3.4%.

Al needs to be 0.002 to 0.4%. Al lowers the transformation temperature by lowering the oxygen content of the weld metal, and its oxide acts as a transformation nucleus of acicular ferrite which improves toughness. Such an effect of Al can be obtained at 0.002% or more.
If it exceeds 0.4%, bainite is formed, the strength of the weld metal becomes excessive, and the toughness deteriorates. In order to further enhance the above effects, the lower limit of the amount of Al added is preferably set to more than 0.03%.

P must be 0.015% or less, and S must be 0.01 or less. In the present invention, since a large amount of Ni is contained for improving the toughness of the weld metal, P and S
Is easily precipitated at the grain boundaries and the toughness is likely to be deteriorated.

N needs to be 0.005% or less. N is an element that deteriorates the toughness, and the toughness of the weld metal deteriorates, so the upper limit was made 0.005%.

Next, the reasons for limiting the bulk specific gravity of the groove filler of the present invention will be described. Even when the composition of the components is limited as described above, the bulk specific gravity needs to be specified in the range of 4 to 6 in order to obtain a good weld bead and a required amount of deposited metal. FIG. 1 shows the relationship between the bulk specific gravity of the groove filler of the present invention and the height of the back bead. As shown in the figure, when the bulk specific gravity is small, the back bead tends to come out, and as the size becomes large, there is a tendency that the back bead becomes less. When the fill thickness to the groove is 4 mm or less from the surface, the bulk specific gravity is 4 mm. If it is less than 10, the back bead becomes excessively large, so that the amount of weld metal is insufficient.However, if the bulk specific gravity exceeds 6, the back bead is difficult to come out and becomes too small. .

In the present invention, in order to improve the shape of the back bead, it is necessary to regulate the bulk specific gravity to the above range. However, if the particle size of the filler is small, the escape of gas generated from the weld metal during welding becomes worse. However, if it is too large, it will be difficult to dissolve. Therefore, it is preferable to further set the particle size of the filler to 0.5 to 2 mm.

Next, the reasons for limiting the welding method using the groove filler of the present invention will be described. The low-temperature steel to which the present invention is directed is mainly used for LPG ships in the field of shipbuilding, and is specified by JIS G3126 or equivalent thereto.
C: 0.05-0.12%, Si: 0.05-0.3
%, Al: 0.002 to 0.045%, Ti: 0.00
Steel containing 5 to 0.02% and N: 0.005% or less, with the balance being iron and unavoidable impurities. In the present invention,
It is assumed that a so-called simple single-sided submerged arc welding method, in which a steel sheet having the above-described composition is brought into contact with a refractory oxide-based backing material on the groove back surface and welded in one layer, is used.

According to the present invention, in the above simple single-sided submerged arc welding method, it is required that the groove filler is used and the welding wire and the flux are further defined. The reasons for the limitation will be described below. First, the reasons for limiting the component composition of the welding wire will be described.

C needs to be 0.01 to 0.1%. C must be set low to obtain good toughness. In order to obtain good low-temperature toughness with the weld metal, the C content of the weld metal must be reduced to 0.1% or less,
0.1% or less. However, if it is less than 0.01%, deoxidation becomes insufficient and toughness deteriorates.

The content of Si must be 0.05% or less. Si is useful as a deoxidizing element. However, in the present weld metal, if the content exceeds 0.05%, the toughness deteriorates. Therefore, the upper limit is set to 0.05%.

Mn needs to be 0.6 to 1.6%. Mn is necessary for securing the hardenability of the weld metal and generating transformation nuclei for intragranular ferrite. Such an effect of Mn can be obtained at 0.6% or more, but 1.6% or more.
If it exceeds, the hardenability of the weld metal becomes excessive and the toughness deteriorates.

Ni needs to be 2.4 to 3.4%. Ni forms a solid solution in the matrix of the weld metal to increase the toughness of the ferrite itself. Such an effect of Ni can be obtained at 2.4% or more in the present weld metal. on the other hand,
If it exceeds 3.4%, P and S are likely to precipitate at the grain boundaries,
Hot cracking is likely to occur.

Al needs to be 0.002 to 0.5%. Al lowers the oxygen content of the weld metal and its oxide acts as a transformation nucleus of acicular ferrite to improve toughness. Such an effect of Al is as follows.
In this weld metal, it can be obtained at 0.002% or more.
%, Bainite is formed, the strength becomes excessive and the toughness deteriorates.

P must be 0.015% or less, and S must be 0.01 or less. In the present invention, since a large amount of Ni is contained for improving the toughness of the weld metal, P and S
Is likely to precipitate at the grain boundaries and deteriorate in toughness, so the content is limited to 0.015% or less and 0.010 or less, respectively.

N needs to be 0.0050% or less. N is an element that degrades toughness, and the toughness is degraded even if other toughness measures are taken.
%.

The diameter of the welding wire is 4.4 to 6.6 mm.
It is necessary to be. When the thickness of the steel plate to be welded is small, the heat input is small, so that the smaller the diameter of the welding wire to be used, the more advantageous it is. When the welding wire diameter is less than 4.4 mm, the back bead is too large and the welding amount is insufficient. When the welding wire diameter exceeds 6.6 mm, the back bead is difficult to appear, and when the current is increased, the welding amount is excessive. Therefore, the range is defined as 4.4 to 6.6 mm.

In the welding method of the present invention, a bond flux is used as a flux in order to improve the toughness of the weld metal by controlling oxygen. Since the molten flux generally used for submerged arc welding contains an oxide as a main component, it is necessary to deoxidize the weld metal by using a welding wire.
Since the amount is limited low, deoxidation becomes insufficient, and improvement in toughness at low temperatures cannot be expected. On the other hand, the bond flux contains CO ₂ in the flux, and C is supplied to the molten metal by the flux, so that the deoxidation is improved.

In the present invention, the above-mentioned bond flux is employed, and from the viewpoint of controlling the oxygen of the weld metal, the basicity Bn of the flux defined by the following equation (1) is set to 0.8 to 1.5.
To That is, if Bn is less than 0.8, the amount of oxygen in the weld metal increases, and good toughness cannot be obtained. On the other hand, Bn
Exceeds 1.5, the oxygen content becomes too low and the toughness deteriorates. Bn = (0.108 [CaO] +0.068 [MnO] +0.10 [MgO]) / (0.105 [SiO ₂ ] +0.002 [Al ₂ O ₃ ]) (1)

The reason for limiting the composition of the flux in the present invention will be described. SiO ₂ is required to be 10 to 20%. SiO ₂ is the most important component for forming a good weld bead in large heat input welding, but when it is excessive, it deteriorates toughness. In other words, if it is less than 10%, the uniformity of the front bead is poor, resulting in a failure. If it exceeds 20%, good toughness cannot be obtained.

MgO needs to be 20 to 33%. MgO is a component useful for ensuring workability in large heat input welding. If it is less than 20%, the surface of the front bead becomes disordered and defective. On the other hand, if it exceeds 33%, a projecting bead is intermittently formed on the surface of the front bead.

Al ₂ O ₃ needs to be 13 to 25%. Al ₂ O ₃ is a component useful for ensuring the slag removability of the front bead. If it is less than 13%, the releasability of the front bead deteriorates, and if it exceeds 25%, it becomes a convex bead.

TiO ₂ needs to be 5 to 15%. TiO ₂ is a component useful for obtaining the surface smoothness of the front bead. In addition, it is effective in improving toughness. Such an effect can be obtained by adding 5% or more, but if it exceeds 15%, the rising angle of the edge of the front bead becomes large.

CaF ₂ needs to be 6 to 12%. Although CaF ₂ is effective in improving toughness, the smoothness of the surface bead surface is impaired in large heat input welding due to its low melting point. That is, if it is less than 6%, there is no effect in improving toughness. On the other hand, if it exceeds 12%, the front bead becomes defective.

CaCO ₃ needs to be 5 to 8%. CaCO ₃ is effective in reducing the amount of diffusible hydrogen in the weld metal. Such an effect can be obtained at 6% or more, but when it exceeds 12%, a pock mark is easily generated, and the front bead becomes defective. Note that the CaCO ₃ and the CaF ₂ are calculated by calculating the basicity Bn as described above.
It is converted to aO.

B ₂ O ₃ needs to be 0.2 to 0.5%. B ₂ O ₃ is effective in improving toughness. Such an effect can be obtained at 0.2% or more. On the other hand, when it exceeds 0.5%, the weld metal hardens and the toughness deteriorates.

The above are the limited conditions required in the simple single-sided submerged arc welding method of the present invention, and other conditions need not be particularly defined, but it is more preferable to perform welding under the following conditions. The thickness of the steel plate to be welded in the simple single-sided submerged arc welding of the present invention is 10 from the viewpoint of the heat-affected zone characteristics and the welding efficiency of the target low-temperature steel.
It is preferable to use a steel plate of up to 25 mm.

The groove angle and root gap of the steel plate to be welded need not be particularly specified, but the groove angle of the steel plate to be welded is 40 to 60 ° and the root gap is 6 mm.
It is more preferable to set the following. With respect to the root gap, a control effect of the back bead shape by the groove filler can be obtained at 1.5 to 6 mm. When the depth of the groove filler is more than 4 mm from the surface of the steel plate, the back bead becomes excessively large and the amount of deposited metal is insufficient.

[0047]

EXAMPLES The effects of the present invention will be more specifically shown by the following examples. Eight types of groove fillers A1 to A8 shown in Table 1 were produced. Of these, A1 to A4 are groove fillers of the present invention, and A4 to A8 are groove fillers of comparative examples for clarifying the effects of the present invention. Similarly, W1 to W shown in Table 2
5 were prepared. Of these, W1
W3 is a wire of the example of the present invention, and W4 and W5 are wires of a comparative example for clarifying the effect of the present invention. The wire diameter was 6.4 mm for all wires. In W1, 4.0, 4.8 and 7.2 mm were further prepared.

[0048]

[Table 1]

[0049]

[Table 2]

The flux was one of F1 to F11 shown in Table 3.
A bond flux of one composition was produced. Of these, F1 to F3 are fluxes of the present invention, and F4 to F13 are fluxes of comparative examples for clarifying the effects of the present invention. The flux was granulated with water glass, baked at 500 ° C. for 1 hour, sized to 12 × 100 mesh and tested.

[0051]

[Table 3]

The groove shown in FIG. 2 is constituted by the steel plates shown in Table 4, and the groove-filled iron alloy shown in Table 1 is sprayed into the groove using the groove conditions shown in Table 5, and the wire and the table shown in Table 2 are used. Using the flux of No. 3, welding was performed under the conditions shown in Table 5. The steel plate is SLA325 and is a low-temperature steel. In FIG. 2, 1 is a backing material mainly composed of a solid refractory oxide, and 2 is a glass tape.

[0053]

[Table 4]

[0054]

[Table 5]

After the welding was completed, the front bead and the back bead were evaluated. Thereafter, a mechanical test and a macro test were performed.
A JIS A1 tensile test piece and a JIS No. 4 V-notch Charpy test piece were each taken from the welded portion 7 mm below the plate surface and tested. In addition, the presence or absence of welding cracks was observed from the cross-sectional macrostructure. The results are shown in Tables 6 and 7.

[0056]

[Table 6]

[0057]

[Table 7]

In Tables 6 and 7, symbols B1 to B9 are examples of the present invention, and symbols B10 to B24 are comparative examples for clarifying the effects of the present invention. As a result, Examples B1 to B9 of the present invention showed good welding workability, no cracking, and good values of tensile strength and Charpy absorbed energy at -55 ° C.

Among the comparative examples, B10 contained too much C and Mn in the groove filler, resulting in excessive tensile strength, and Ni and Al.
Was insufficient and toughness was deteriorated. Of the comparative examples, B11 had an excessively small backing bead due to an excessively low bulk specific gravity of the groove filler, and a high-temperature crack occurred due to excessive amounts of Ni and P. Among the comparative examples, B12 contained excessive amounts of Mn and N in the groove filler, resulting in excessive tensile strength and further deterioration in toughness.

In Comparative Example B13, the bulk specific gravity of the groove-filled iron alloy was too large, and the back bead was hard to appear and was too small. Among the comparative examples, B14 had an excessively large wire diameter and hardly produced a back bead, and was too small. Among the comparative examples, B15 had an excessively small wire diameter and an excessively large back bead.

Of the comparative examples, B16 had insufficient Al in the wire and too much N, resulting in poor toughness. B in Comparative Example
In No. 17, the wire had too much Ni and P, and hot cracking occurred. B18 of the comparative example excessive tensile strength Bn flux becomes excessive, further SiO ₂ tables bead becomes uneven in under-table bead in further Al ₂ O ₃ is excessively becomes convex.

In the comparative example, B19 is flux SiO 2
₂ is excessive and Bn is too small to deteriorate toughness.
The gO was too small and the surface of the front bead was disturbed. B2 out of the comparative examples
0 intermittently projections in Table bead surface MgO of flux in excess occurs, TiO ₂ has poor smoothness of the table bead for under-. Among the comparative examples, B21 is flux CaF
No. ₂ and too little Bn resulted in toughness deterioration.

B22 of the comparative example was made of flux TiO.
₂ is excessive, the toe ends of the front bead are not uniform, and CaF ₂
Was excessive, and the smoothness of the front bead was poor. B2 out of the comparative examples
No. ₃ is excessive in B ₂ O 3 of the flux and the weld metal is hardened,
The tensile strength became excessive. Among Comparative Examples B24 is _B 2 _{O 3} in flux toughness in too little is deteriorated.

[0064]

According to the present invention as described above,
As shown in the examples, in the simple single-sided submerged arc welding method for low-temperature steel, a welded part having good welding workability and good back bead shape, no welding cracks, and good low-temperature toughness is obtained, and for welding large structures. It is a great place to contribute.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the bulk specific gravity of a groove-filled iron alloy and the height of a back head.

FIG. 2 is a sectional view showing a groove shape of a steel sheet used in an example of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noriyuki Ohama 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Corporation Technology Development Division (72) Inventor Naoaki Matsuya 20-1 Shintomi, Futtsu City, Chiba Prefecture New Japan F-term in the Technology Development Division of Steel Corporation (reference) 4E001 AA03 BB05 CA05 DC01 DC03 DC05 DF00 EA04 EA05 EA07 EA09 4E084 AA02 AA03 AA07 AA11 AA13 AA20 AA26 BA23 DA18 DA31 EA04 GA04 HA04

Claims (4)

[Claims] 1. In a simple one-sided groove filler for submerged arc welding, C: 0.07% or less and Si:
0.05% or less, Mn: 0.6 to 1.5%, Ni: 2.
4 to 3.4%, Al: 0.002 to 0.4%,
P: 0.015% or less, S: 0.01% or less, N: 0.
A groove filler for simple single-sided submerged arc welding, wherein the steel grain is 005% or less and the bulk specific gravity is 4 to 6. 2. The steel grain having an Al content of more than 0.03 to 0.4.
%. The groove filler for simple single-sided submerged arc welding according to claim 1, wherein 3. The groove filler for simple single-sided submerged arc welding according to claim 1, wherein the particle size is 0.5 to 2 mm. 4. A refractory oxide is provided on the back side of the groove of the steel plate for low temperature use.
A single-layer welding by contacting a backing material containing
In the easy single-sided submerged arc welding method, the groove
Is filled with the groove filler according to any one of claims 1 to 3.
And in weight%, SiO₂: 10 to 20%, MgO: 2
0-33%, Al₂O₃: 13-25%, TiO₂: 5
~ 15%, CaF₂: 6-12%, CaCO₃: 5-8
%, B ₂O₃: Containing 0.2 to 0.5%, and
A bond flux having a defined Bn of 0.8 to 1.5.
C: 0.01 to 0.1%, Si: 0.
05% or less, Mn: 0.6 to 1.6%, Ni: 2.4 to
3.4%, Al: 0.002-0.5%, P:
0.015% or less, S: 0.010% or less, N: 0.0
05% or less, and the wire diameter is 4.4 to 6.6 mm
Using a certain steel welding wire, the root gap of the groove is used.
Characterized in that welding is performed with a gap of 6 mm or less.
Simple one-sided submerged arc welding method for warm steel. Bn = (0.108 [CaO] +0.068 [MnO]
+0.10 [MgO]) / (0.105 [SiO₂] +
0.002 [Al₂O₃])