JPS6046895A - Groove filler for one-side submerged arc welding - Google Patents

Abstract

PURPOSE:To form a weld zone having an excellent mechanical characteristic and resistance to crack in the stage of performing one-side submerged arc welding of steel for low temperature service by using a high Ni wire by using a groove filler compounded with Ni, Mo, Bi and Pb at specific ratios. CONSTITUTION:A groove filler for one-side submerged arc welding of steel for low temperature service by using a high Ni wire is formed of the compsn. consisting of >=30wt% Ni, >=15wt% Mo and 0.005-1wt% Bi and/or Pb alone and/or compd. thereof in terms of Bi or Pb. Bi2O3, Bi2(OH)3, BiF3, PbO, PbO2, PbF2, etc. are used as the compd. of Bi and Pb. Detachability of slag is thus improved and the penetration bead having a uniform shape is obtd. without slag burn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a groove filler for single-sided submerged arc welding, and more particularly, it provides a welded part with excellent mechanical properties and cracking resistance, and has good slag removability. The present invention relates to a groove filler for single-sided submerged arc welding that allows obtaining a uniformly shaped Uranami bead without slag burning.

When welding low-temperature steel such as 9% Ni steel, the submerged arc welding method is widely used due to its high efficiency, so after the welding inside the front side is completed, the top is lifted, and the back side welding is carried out. So-called double-sided welding is used.

On the other hand, in the field of thin plate welding where the problem of angular deformation is less likely to occur, welding is performed only from the front side in order to further improve welding efficiency. So-called single-sided submerged arc welding is being considered. However, when single-sided welding is used for thin plates, in the first layer welding part where the molten amount ratio of the base metal is relatively large, the degree of dilution by the molten base metal increases and the Fe content ratio in the weld metal increases. A problem arises in that the content ratio of the alloying elements supplied from the alloy decreases, and the mechanical properties deteriorate.

Furthermore, since a backing material is normally used in such single-sided submerged arc welding, in order to obtain a good and uniform uranami bead, it is necessary to use a backing material that has good adhesion to the base metal. Examples of the backing material include a glass tape-based backing material made of a combination of glass tape and Cu, or a combination of glass tape and fire-resistant solid flux. However, when this is used, the SiO2 in the glass tape tends to cause slag to burn onto the Uranami bead, resulting in poor slag removability and removal of the slag using a grinder, etc. after welding. The problem arises that work must be done. Regarding slag removability, various improvement methods have been studied, for example, B in flux for submerged arc welding.
The method of adding i etc. was published in Japanese Patent Publication No. 55-51677.
and JP-A-58-41695. It is true that this method improves the slag removability itself, but
For example, as passes are repeated in multi-layer welding, Bi and other substances accumulate in the weld metal and its content gradually increases, resulting in a marked deterioration in cracking properties, a decrease in bead spread, and impairing welding workability. appears. In other words, although slag peelability is a problem in the first layer welding part, in the disclosed method, the welding conditions (flux) for the first layer part and the second and subsequent layers are exactly the same, so when welding the first layer, Added Bi etc. act to improve slag removability, but
During welding after 2nd layer 1, the above-mentioned Bi etc. are mixed and accumulated as alloying elements in the weld metal by fermentation, so B in the weld metal
It is thought that the increase in gold content such as i has an adverse effect on crack resistance and impairs welding workability.

The present invention has been developed in view of these circumstances, and has excellent mechanical properties and cracking resistance, as well as a uniformly shaped uranami bead with good slag removability and no seizure. The present invention aims to provide a groove filler for single-sided submerged arc welding.

The groove filler for single-sided submerged arc welding of the present invention, which has achieved the above object, is a groove filler for single-sided submerged arc welding of low-temperature steel using a high Ni alloy wire, and has Ni: 30. % (meaning of weight %, the same applies hereinafter) or more Mo: 1
The gist is that it contains 0.005 to 1% in terms of Bi or Pb (substance and/or compound of Bi and/or Pb) of 5% or more. In other words, by intensively supplying Ni and Mo to the bottom of the groove, the deterioration of mechanical properties, which is a fundamental problem during first layer welding, can be solved, and by supplying Ni and Mo to the bottom of the groove.
It has become possible to improve the slag removability and maintain good crack resistance and welding workability of the mouth weld metal by intensively supplying Ni and Bi.

In the field of welding according to the present invention, that is, single-sided latent arc welding of low-temperature steel, such as 9% Ni steel, using high Ni wire, such as high Ni alloy wire such as Inconel or Hastelloy, the composition of the weld metal and base metal is This is extremely different metal welding, and as mentioned above, during first layer welding, the molten ratio of the base metal is large, so the degree of dilution by the molten base metal becomes high, and the composition of the first layer weld metal differs from the target composition. It's easy to become a thing.

Therefore, when welding the first layer weld, the inventors focused on a groove filler that can obtain a stable uranami bead even if there are variations in the groove gap or misalignment. ,
Even if the flux for submerged arc welding remains the same as before, it is possible to control only the composition of the first layer weld metal by devising the composition of the groove filler. As a result of repeated research, we were able to successfully achieve this objective by adopting the above configuration.

The composition of the groove filler according to the present invention will be explained below.

Ni and MO are components to maintain the composition of the first layer weld metal, which is highly diluted, to be the same as that of the second and subsequent layer weld metals, and prevent deterioration of the crack resistance and mechanical properties of the first layer weld metal. , good weldability.

It is an essential ingredient for maintaining Ni is an element necessary to increase the mechanical strength of the weld metal and ensure low-temperature toughness, and if the content is less than 30%, the above effects cannot be fully exhibited.

Furthermore, MO is an effective element for improving the weld metal's cracking properties and increasing its mechanical strength, and if the content is less than 15%, the above effects cannot be fully exhibited.

In addition to these, the groove filler of the present invention contains Bi and/or Pb in an amount of 0.005 to 1.0% in terms of Bi or Pb.

That is, since the intermediate metals of Bi and Pb and their compounds have low melting points, adding them lowers the melting point of the molten slag, increases fluidity, and lowers the surface tension, which improves the interface with the weld metal. Tension increases. In addition, the metal vapor generated accelerates the separation of the slag,
Burnout of the slag is prevented and the releasability of the uranami bead from the slag is improved. If the content is less than 0.005%, the expected effect will not be exhibited, while if it exceeds 1.0%, the cracking resistance will be significantly reduced. Further, the above-mentioned Bi and Pb are added as intermediates or compounds, and examples of the above-mentioned compounds include Bi203, Bi2 (OH)3, BiF3. Bi
Cl3. B1Br3. BiI3, PbO1PbO2,P
bF2. Examples include PbC12.

The groove filler of the present invention is a composition containing the above-mentioned components as essential components, and there are no particular restrictions on the composition other than the above, such as Fe-3i, Fe-Al, Fe-Ti'; (7) Even if a deoxidizing agent and alloying elements such as Mn, Cr, and Nb are blended in arbitrary proportions, the characteristics of the groove filler according to the present invention will not be impaired. Further, each of the filler components described above is desirably blended as a powder of 250 pLm or less in order to prevent segregation within the weld metal.

When carrying out single-sided submerged arc welding of low-temperature steel using the groove filler of the present invention as described above, a glass tape-based backing material is brought into contact with the back surface of the base metal groove, and the groove is Sprinkle a necessary and sufficient amount of groove filler to immerse the first layer weld metal part, but not too much, and further sprinkle flux for submerged arc welding on top of it. Next, a wire made of high Ni alloy is inserted into the groove and multi-layered single-sided latent arc welding is performed.

The present invention is configured as described above, and can obtain the effects summarized below.

(1) Ni and M contained in the groove filler in a predetermined amount or more
Since O is supplied to the first layer weld metal during welding, the mechanical properties and crack resistance of the first layer weld metal will not deteriorate even if it is diluted by the molten base metal.

(2) Bi and/or Bi contained in the groove filler in a predetermined amount or more
Alternatively, the fluidity, surface tension, etc. of the molten slag are improved by the suspension of Pb and/or the compound, so that the peelability between the slag and the Uranami beads becomes good, and uniform and good Uranami beads can be obtained.

(3) Since Bi and/or Pb is not mixed in the beads in the second and subsequent layers, welding workability and crack resistance do not deteriorate in the second and subsequent layers.

Next, examples of the present invention will be shown.

The groove filler with the composition shown in Table 1 and the m-arc welding flux (granulated and fired with water glass as a fixing agent) with the composition shown in Table 2 are used, and the chemical composition shown in Table 3 is used. Single-sided submerged arc welding of 9% Ni steel having the chemical composition shown in Table 4 was performed in three layers using a wire having the composition, and welding workability, hot cracking susceptibility in the first layer, and mechanical properties were investigated. 6th result
Shown in the table. The groove shape of the welded part is as shown in Figure 1. A backing material made of glass tape G and copper plate A is brought into contact with the back side of the V-shaped groove, and the groove is extended to a height of 6 mm from the bottom of the groove. The filler B is spread, and the submerged arc welding flux C is also spread thereon, and the wire W is further inserted. The welding conditions are shown in Table 5.

Table 2 Table 3 of ω σO 3 Table 4 (%) Table 5 (%) 4 As shown in Tables 1 and 6, No. 8 and No.
In No. 09, the converted content of Bi and/or Pb in the groove filler was less than 0.005%, so slag burned onto the Uranami bead. On the contrary, in Nos. 10 to 2, hot cracking occurred in the initial layer bead because the converted content of Bi and/or Pb exceeded 1.0%. Moreover, this excess i or Pb had an adverse effect on the final bead (third pass layer), reducing the bead spreading and worsening welding workability. In No. 13, since the MO content was less than 15%, the Mo content in the first layer weld metal decreased too much due to base metal dilution, resulting in a decrease in crack resistance and mechanical strength. In No. 14, the Nf content was less than 30%, so the initial layer weld metal was strongly diluted from the base metal, resulting in a decrease in strength and a significant decrease in low-temperature toughness. For these, no.

Nos. 1 to 7 contained appropriate amounts of Ni, Mo, Bf, Pb, etc., and therefore had good welding workability, high temperature cracking susceptibility in the first layer, and mechanical properties.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view 7 showing the groove shape applied to the example. A...Copper plate B...Groove filler C...Flux for submerged arc welding G...Glass tape W...Wire applicant Kobe Steel, Ltd. 8

Claims (1)

[Claims] A groove filler for single-sided submerged arc welding of low-temperature steel using a high Ni wire, comprising Ni: 30% (meaning by weight %, the same applies hereinafter) or more Mo: 1
A groove filler for single-sided submerged arc welding, characterized in that it contains 5% or more of Bi and/or Pb alone and/or compounds: 5 to 1% of Theo and Oo in terms of Bi or Pb.