JP2018144060A - Filler metal for tig welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide filler metal for TIG welding, which suppresses excess hardness of weld metal causing a delayed crack in single-layer welding, and which satisfies the welding joint performance (strength, toughness and the like) required as a welding material for 400 MPa class steel in multilayer welding.SOLUTION: Filler metal for TIG welding according to the present invention includes 0.02-0.06 mass% C, 0.30-0.85 mass% Si, and 0.70-1.40 mass% Mn. Each of Ni, Cr, Mo, V, P, S and N contents is regulated to a predetermined value or below. Residues comprise Fe and inevitable impurities, and a carbon equivalent Ceq is in the range of 0.15-0.35.SELECTED DRAWING: None

Description

The present invention relates to a filler material for TIG (Tungsten Inert Gas) welding. More particularly, particularly useful as TIG welding material for low-strength steel having a 400 N / mm ² class tensile strength, it relates to TIG welding filler material.

  Conventionally, various steel materials have been used as rolled steel for welded structures. For example, steel materials having a tensile strength of 400 MPa class (400 MPa class steel) represented by rolled steel SM400 (JIS G3106) for welded structures are used. Yes. In the case of welding a structure, generally, when a load is applied to the structure, the structure is designed so that fracture occurs in the base material portion, not the welded portion. Therefore, generally, the welded portion is required to have higher strength than the base material. Here, in JIS Z3316, standards for TIG welding filler rods and solid wires for mild steel, high-tensile steel and low-temperature steel are defined.

  Here, in TIG welding of carbon steel, generally, high-purity argon (Ar) gas is used as a shielding gas. Since argon gas does not cause an oxidation reaction in the molten pool, the oxygen content of the weld metal is significantly lower than other welding methods. Therefore, TIG weld metal has a property of being excellent in strength and toughness with few inclusions such as oxides.

However, since carbon steel with a small amount of oxygen has the property that the hardenability is very high, there is a problem in that the strength and hardness of the original part of the weld metal are greatly increased. In particular, in the case of a thick plate, the cooling rate is faster than in the case of a thin plate, and the hardenability is further improved. As a result, there is a problem that excessive hardness is promoted.
Also, in areas that are not subjected to reheating due to welding, such as the final layer or single layer welding in multilayer welding, the structure becomes the original part, so the hardness may become excessively high, delayed cracking or sulfide stress corrosion cracking (SSCC) may occur. These cracks depend on the amount of diffusible hydrogen in the weld metal and the restraining force applied to the weld metal, but generally, cracks are likely to occur when the Vickers hardness of the weld metal is HV350 or higher. ing.

  Here, as a method for reducing the hardness of the welding material, a method is known in which the welding heat input is increased in order to reduce the cooling rate and the preheating temperature and the interpass temperature are increased. In addition, as post-weld heat treatment (PWHT), a method of tempering the structure by annealing the hardened original part and reducing the hardness is also known.

  However, these methods have the problem that man-hours increase, productivity decreases, and costs increase. Further, the increase in welding heat input has an effect on the heat affected zone (HAZ), and there is a problem that the joint strength cannot be secured. Furthermore, the post-weld heat treatment (PWHT) also has a facility restriction that it is difficult to apply the heat treatment depending on the size of the furnace and the size of the welded structure.

  As a welding material, for example, in Patent Document 1, C is 0.03% by weight or less, Si is 0.05% by weight or less, Mn is 0.80% by weight or less, Ti is 0.008% by weight or less, A solid wire for gas shielded arc welding is described in which O is regulated to 0.025% by weight or less, and the balance is made of Fe and inevitable impurities.

JP-A-11-221672

  The solid wire for gas shielded arc welding described in Patent Document 1 is effective for suppressing the excessive hardness of the weld metal in single layer welding. However, since the strength of the weld metal including the reheated portion such as multilayer welding is softer than the strength of the steel plate, the solid wire for gas shielded arc welding described in Patent Document 1 is required as a welding material for 400 MPa class steel. There is a problem that the welded joint strength cannot be satisfied. That is, all of the weld metals using the solid wire for gas shielded arc welding described in Patent Document 1 have a tensile strength lower than 400 MPa. In addition, although it is conceivable to reduce the hardness of the original part by performing only the final layer, which is excessively hard in multilayer welding, with the wire, there is a problem in terms of wire management and efficiency of welding work.

  In view of the above-described conventional problems, the present invention suppresses the excessive hardness of the weld metal that causes delayed cracking in single-layer welding, and weld joint performance (strength, required) as a welding material for 400 MPa class steel in multilayer welding. An object is to provide a filler metal for TIG welding that satisfies toughness and the like.

In order to achieve the object, the present invention contains C: 0.02-0.06 mass%, Si: 0.30-0.85 mass%, and Mn: 0.70-1.40 mass% Ni: 0.10 mass% or less (including 0 mass%), Cr: 0.10 mass% or less (however, including 0 mass%), Mo: 0.10 mass% or less (however, 0 V: 0.05 mass% or less (however, 0 mass% is included), P: 0.030 mass% or less (however, 0 mass% is not included), S: 0.030 mass% It is controlled to the following (however, not including 0% by mass) and N: 0.0100% by mass or less (however, not including 0% by mass), the balance is composed of Fe and inevitable impurities, and the following formula Provided a filler material for TIG welding in which the carbon equivalent Ceq represented by (1) is in the range of 0.15 to 0.35. That.
Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14 (1)
(However, [C], [Si], [Mn], [Ni], [Cr], [Mo] and [V] are the contents of C, Si, Mn, Ni, Cr, Mo and V, respectively ( Mass%).)

  Here, in the filler material for TIG welding of the present invention, the carbon equivalent Ceq may be within a range of 0.20 to 0.33.

Further, the filler metal for TIG welding of the present invention has Al: 0.10% by mass or less (including 0% by mass), Ti: 0.10% by mass or less (however, 0% by mass), Zr : At least one selected from the group consisting of: 0.10% by mass or less (including 0% by mass) and O: 0.0100% by mass or less (however, not including 0% by mass); In addition, the relationship of the following formula (2) may be satisfied.
[X] = ([Ti] + [Al] + [Zr]) × [O] × 10000 ≦ 10.0 (2)
(However, [Ti], [Al], [Zr], and [O] indicate the contents (mass%) of Ti, Al, Zr, and O, respectively.)

  Moreover, the filler material for TIG welding of this invention may further contain Cu: 0.50 mass% or less (however, 0 mass% is included).

  The filler metal for TIG welding according to the present invention suppresses the excessive hardness of the weld metal that causes delayed cracking in single layer welding, and also provides weld joint performance (strength, toughness) required as a welding material for 400 MPa class steel in multilayer welding. Etc.). Therefore, the filler material for TIG welding of the present invention is particularly useful as a TIG welding material for 400 MPa class steel.

FIG. 1 is a view showing the shape of a base material used for multi-layer welding (all-welded metal), FIG. 1 (a) is a plan view, and FIG. 1 (b) is a cross-sectional view. 2A and 2B are explanatory views showing a state of single-layer fillet welding, FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

The filler material for TIG welding of the present embodiment (hereinafter, also simply referred to as “the filler material”) is C: 0.02 to 0.06 mass%, Si: 0.30 to 0.85 mass%, and Mn: 0.70 to 1.40 mass%, Ni: 0.10 mass% or less (however, 0 mass% is included), Cr: 0.10 mass% or less (however, 0 mass% is included) , Mo: 0.10% by mass or less (including 0% by mass), V: 0.05% by mass or less (however, including 0% by mass), P: 0.030% by mass or less (however, 0% by mass) %), S: 0.030 mass% or less (however, 0 mass% is not included), and N: 0.0100 mass% or less (however, 0 mass% is not included). Is composed of Fe and inevitable impurities, and the carbon equivalent Ceq represented by the following formula (1) is 0.15 to 0.35. It is within the range.
Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14 (1)
(However, [C], [Si], [Mn], [Ni], [Cr], [Mo] and [V] are the contents of C, Si, Mn, Ni, Cr, Mo and V, respectively ( Mass%).)

  Below, the reasons for limitation such as the chemical composition of the filler material of the present embodiment will be described. In the following description, the percentage (%) in the description of the composition represents the percentage (mass%) based on mass unless otherwise specified. In this specification, it is assumed that mass% is the same as weight%.

(C: 0.02-0.06%)
C is an element having an effect of improving strength and hardness by dissolving in a weld metal. When the C content in the filler metal is 0.02% or more, the effect of improving the strength is sufficiently exhibited, and it becomes possible to ensure the strength of a weld metal suitable as a welding material for 400 MPa class steel. Further, when the C content in the filler material is 0.06% or less, the hardness does not become too high, and delayed cracks derived from excess hardness can be prevented.
The C content is preferably 0.03% or more. Further, the C content is preferably 0.05% or less.

(Si: 0.30 to 0.85%)
Si is an element having an effect of improving strength and hardness by dissolving in a weld metal. Si also has the effect of improving the familiarity of the bead toe. When the Si content in the filler metal is 0.30% or more, the effect of improving the strength is sufficiently exhibited, and it is possible to obtain an appropriate strength as a welding material for 400 MPa steel, and the familiarity of the bead toe portion. Can be good. Further, when the Si content in the filler material is 0.85% or less, the hardness does not become too high, and delayed cracks derived from excess hardness can be prevented.
The Si content is preferably 0.40% or more, more preferably 0.50% or more. Moreover, Si content becomes like this. Preferably it is 0.80% or less, More preferably, it is 0.70% or less.

(Mn: 0.70 to 1.40%)
Mn is an element having an effect of improving strength and hardness by dissolving in a weld metal. Mn also has the effect of improving toughness. When the Mn content in the filler material is 0.70% or more, the effect of improving the strength is sufficiently exhibited, and it is possible to obtain an appropriate strength as a welding material for 400 MPa class steel and to obtain excellent toughness. be able to. Further, when the Mn content in the filler material is 1.40% or less, the hardness does not become too high, and delayed cracks derived from excess hardness can be prevented.
The Mn content is preferably 0.80% or more, more preferably 1.00% or more. Further, the Mn content is preferably 1.30% or less, and more preferably 1.25% or less.

(Ni: 0.10% or less (including 0%), Cr: 0.10% or less (however, including 0%), Mo: 0.10% or less (however, including 0%), and V: 0.05% or less (including 0%))
Ni, Cr, Mo and V are elements having an effect of improving the hardness, but if contained excessively, the hardness becomes too high, and there is a possibility that delayed cracks derived from the excessive hardness occur.
Therefore, these elements may or may not be contained in the filler material, but even if contained, each content in the filler material is Ni. 0.10% or less, Cr is 0.10% or less, Mo is 0.10% or less, and V is 0.05% or less.
The Ni content is preferably regulated to 0.05% or less.
Further, the Cr content is preferably regulated to 0.05% or less.
Further, the Mo content is preferably regulated to 0.05% or less.
Further, the V content is preferably regulated to 0.02% or less.

(Carbon equivalent Ceq: 0.15-0.35)
In the filler material of this embodiment, the carbon equivalent Ceq represented by the following formula (1) is in the range of 0.15 to 0.35.
Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14 (1)
(However, [C], [Si], [Mn], [Ni], [Cr], [Mo] and [V] are the contents of C, Si, Mn, Ni, Cr, Mo and V, respectively ( Mass%).)

When the carbon equivalent Ceq is 0.15 or more, an appropriate strength improvement effect is obtained, and an appropriate strength can be obtained as a welding material for 400 MPa class steel. Further, when the carbon equivalent Ceq is 0.35 or less, the hardness does not become too high, and delayed cracking derived from excess hardness can be prevented.
The carbon equivalent Ceq is preferably 0.20 or more. The carbon equivalent Ceq is preferably 0.33 or less.

(P: 0.030% or less (excluding 0%), and S: 0.030% or less (excluding 0%))
P and S are elements inevitably present in the filler metal, but have the effect of increasing hot cracking susceptibility and decreasing toughness. Therefore, the P content in the filler metal is regulated to 0.030% or less, and the S content is regulated to 0.030% or less. The P content is preferably regulated to 0.025% or less. Further, the S content is preferably regulated to 0.025% or less. The P and S contents are preferably as small as possible, but it is usually difficult to prevent the filler material from containing these elements at all. Therefore, if the lower limit value of the contents of P and S is specified, it is, for example, more than 0%.

(N: 0.0100% or less (excluding 0%))
N is an element unavoidably present in the filler metal, but has an effect of reducing toughness. Therefore, the N content in the filler metal is regulated to 0.0100% or less. The N content is preferably regulated to 0.0070% or less. The N content is preferably as small as possible, but it is usually difficult to prevent the filler material from containing N at all. Therefore, if the lower limit value of the N content is specified, for example, it is over 0%.

  Moreover, in addition to each element mentioned above, the filler material of this embodiment may further contain the following elements as long as it is below a predetermined content.

(Al: 0.10% or less (including 0%), Ti: 0.10% or less (including 0%), Zr: 0.10% or less (however, including 0%), and O: at least one selected from the group consisting of 0.0100% or less (excluding 0%)
Al, Ti, and Zr are elements that have the effect of increasing the strength of the weld metal by solid solution and precipitation, etc., but on the other hand, they combine with O to form an oxide in the weld metal, thereby increasing the elongation and toughness. It is also an element that lowers. Moreover, when these are discharged | emitted out of a weld metal, slag will be formed, it will become welding defects, such as slag entrainment, and also will become a factor which inhibits a bead appearance. O is an element inevitably present in the filler metal. However, when a large amount of O is present, the above-described effects are promoted.
Therefore, Al, Ti, and Zr may be contained in the filler material, or may not be contained, but even in the case of inclusion, each content in the filler material is Al. 0.10% or less if Ti, 0.10% or less for Ti, and 0.10% or less for Zr.
The Al content is preferably 0.05% or more. Further, the Al content is preferably 0.01% or less.
The Ti content is preferably 0.05% or more. Further, the Ti content is preferably 0.01% or less.
The Zr content is preferably 0.05% or more. The Zr content is preferably 0.01% or less.
The O content is 0.0100% or less, preferably 0.0070% or less. The O content is preferably as small as possible, but it is usually difficult for the filler material to contain no O. Therefore, if the lower limit value of the O content is specified, it is, for example, more than 0%.

([X] ≦ 10.0)
Moreover, when the filler material of this embodiment contains at least 1 sort (s) of Al, Ti, Zr, and O within the said range, it is preferable to satisfy the relationship of following formula (2).
[X] = ([Ti] + [Al] + [Zr]) × [O] × 10000 ≦ 10.0 (2)
(However, [Ti], [Al], [Zr], and [O] indicate the contents (mass%) of Ti, Al, Zr, and O, respectively.)

  When [X] represented by the above formula (2) is 10.0 or less, the amount of slag formed can be satisfactorily suppressed, welding defects such as slag entrainment can be prevented, and the appearance is excellent. You can get a bead.

(Cu: 0.50% or less)
Cu is an element having an effect of improving the strength, but if added excessively, the strength becomes too high, and the hot cracking susceptibility increases. Therefore, Cu may be contained in the filler material or may not be contained, but even if it is contained, the Cu content in the filler material is 0.50% or less. .
The Cu content is preferably 0.35% or more. Note that the filler material of the present embodiment may be subjected to Cu plating as desired. Here, in this specification, when Cu plating is performed on the filler material, the Cu content is the Cu content in the filler material and the Cu plating film with respect to the total of the filler material and the Cu plating film. It shall mean content.

  In addition, the remainder in the filler material of this embodiment consists of Fe and an unavoidable impurity. Inevitable impurities other than the above elements include elements such as Nb, Sn, and B. These elements increase the strength of the weld metal by solid solution and precipitation and increase hot cracking susceptibility, so it is preferable to reduce as much as possible, but the content of each element is up to 0.1% If it is within the range, inclusion is allowed.

  As a form of the filler material of this embodiment, a welding rod, a wire, etc. are mentioned, for example. In the present embodiment, the presence / absence of Cu plating on the surface of the filler material, the surface form such as grain boundary oxidation, and the properties of the surface coating oil are not particularly limited. Further, in the present embodiment, the winding shape of the wire is not particularly limited, and for example, a spool winding wire, a packed wire, or the like can be used.

  In addition, when manufacturing the filler material of this embodiment, conventionally well-known various methods can be applied without a restriction | limiting as a manufacturing method of a filler material.

  The filler metal of this embodiment suppresses the excessive hardness of the weld metal that causes delayed cracking in single-layer welding, and weld joint performance (strength, toughness, etc.) required as a welding material for 400 MPa class steel in multilayer welding. Satisfied. Therefore, the filler material of the present embodiment is particularly useful as a TIG welding material of 400 MPa class steel. In addition, the filler material of this embodiment can be suitably used also as TIG welding materials for various steels other than 400 MPa class steel. Further, the filler material of the present embodiment can be appropriately applied to various welding methods other than TIG welding.

  EXAMPLES Hereinafter, although the Example and comparative example of this invention are given and this invention is demonstrated more concretely, this invention is not limited to these Examples.

(All weld metal tensile test, Charpy impact test and slag evaluation)
FIG. 1 is a view showing the shape of a base material used for multi-layer welding (all-welded metal), FIG. 1 (a) is a plan view, and FIG. 1 (b) is a cross-sectional view. As shown in FIG. 1, first, two JIS G3106 SM400B steel plates 1 having notches inclined on the end surface are prepared, the inclined surfaces 1a are opposed to each other, and the tip of the inclined surface 1a is separated by 10 mm. By arranging the steel plates 1, a groove 2 having a groove angle of 45 ° was formed between the two steel plates 1. Next, after placing the backing material 3 made of JIS G3106 SM400B on the back side of the groove 2, the filler material (wire) having various compositions shown in Tables 3 and 4 with respect to the groove 2. Was used to perform multilayer welding (total deposited metal) under the welding conditions shown in Table 1 below. In this test, the plate thickness of the steel plate 1 was 16 mm, the length in the direction parallel to the inclined surface 1 a of the steel plate 1 was 300 mm, and the length in the direction orthogonal to the inclined surface 1 a was 125 mm. The plate thickness of the backing material 3 was 6 mm. In Tables 3 and 4, “-” indicates that the component amount was less than the detection limit. The balance of the composition is Fe and inevitable impurities.

Next, the tensile strength (MPa), 0.2% proof stress (MPa), and elongation (%) were obtained by conducting a tensile test of all the weld metals on the obtained weld metal under the conditions shown in Table 2 below. Measured and evaluated. These results are shown in Tables 5 and 6.
Here, about the tensile strength, the case where it exists in the range of 430-600 MPa was judged favorable, and the case other than that was evaluated as bad.
About 0.2% yield strength, the case of 330 MPa or more was evaluated as good, and the case of less than 330 MPa was evaluated as defective.
Regarding the elongation, the case of 20% or more was evaluated as good, and the case of less than 20% was evaluated as defective.

  Moreover, the absorbed energy (J) was measured and evaluated about the obtained weld metal by implementing the Charpy impact test on the conditions shown in Table 2 below. The results are shown in Tables 5 and 6. Here, the case where the absorbed energy was 100 J or more was evaluated as good, and the case where the absorbed energy was less than 100 J was evaluated as defective.

  Moreover, about the obtained weld metal, the amount of slag was evaluated by visual observation. The results are shown in Tables 5 and 6. Here, the case where it is evaluated that the slag amount is small and the appearance is evaluated is good (◯), the slag amount is large and the appearance is inferior. The case was evaluated as defective (x).

(Vickers hardness test)
2A and 2B are explanatory views showing a state of single-layer fillet welding, FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view. As shown in FIG. 2, a JIS G3106 SM400B steel plate having a width of 150 mm × a length of 200 mm × a plate thickness of 50 mm as the steel plate 4 and a JIS G3106 SM400B steel plate having a width of 70 mm × a length of 200 mm × a plate thickness of 6 mm as the steel plate 5. Prepared. Using these fillers (wires) having various compositions shown in Tables 3 and 4 for the lower plate and the standing plate, the single-layer fillet weld 6 is formed under the welding conditions shown in Table 1 below. Produced.

  Next, about the obtained weld metal, the Vickers hardness HV was measured and evaluated by implementing the Vickers hardness test of the cross-sectional center part of a weld metal on the conditions shown in Table 2 below. The results are shown in Tables 5 and 6. Here, the case where the Vickers hardness was HV350 or less was evaluated as good, and the case where the Vickers hardness exceeded HV350 was evaluated as defective (x).

Experimental Examples 1 to 11 are examples, and Experimental Examples 12 to 25 are comparative examples.
As shown in Tables 3-6, each filler material of Experimental Examples 1-11 has an appropriate chemical composition, so the tensile strength in the tensile test of all weld metals is in the range of 430-600 MPa. In addition, good mechanical performance with a 0.2% proof stress of 330 MPa or more and an elongation of 20% or more was obtained. Furthermore, the Vickers hardness of the single layer fillet weld metal was HV350 or less, which was good. Therefore, each filler material of Experimental Examples 1 to 11 suppresses the excessive hardness of the weld metal that causes delay cracking in single-layer welding, and weld joint performance (as a welding material for 400 MPa class steel in multilayer welding) ( Strength, toughness, etc.).
In Experimental Examples 4 and 9, since [X] was as large as 12.7 and 11.9, respectively, the amount of slag generation was large and the appearance was inferior.

On the other hand, in Experimental Example 12, the Mn content is smaller than the range defined in the present invention, and Ceq is smaller than the range defined in the present invention. Therefore, the 0.2% proof stress and tensile strength of all the deposited metals were insufficient, and the evaluation results were poor.
In Experimental Example 13, the Si content is smaller than the range specified in the present invention. Therefore, the tensile strength of all the weld metals was insufficient, and the evaluation results were poor.
In Experimental Example 14, the C content and the Mn content are smaller than the ranges specified in the present invention, and Ceq is smaller than the ranges specified in the present invention. Therefore, the 0.2% proof stress and tensile strength of all the deposited metals were insufficient, and the evaluation results were poor.

In Experimental Example 15, the C content, the Si content, the Mn content, and the Mo content are larger than the range specified in the present invention, and Ceq is larger than the range specified in the present invention. Therefore, the tensile strength of all the deposited metals was high, the evaluation result was poor, the Vickers hardness exceeded HV350, and the evaluation result was also poor.
In Experimental Example 16, the Si content and the Mn content are larger than the range specified in the present invention, and Ceq is larger than the range specified in the present invention. Therefore, the tensile strength of all the deposited metals was high, the evaluation result was poor, the Vickers hardness exceeded HV350, and the evaluation result was also poor.
In Experimental Example 17, the C content is larger than the range specified in the present invention, and Ceq is larger than the range specified in the present invention. Therefore, the tensile strength of all the deposited metals was high, the evaluation result was poor, the Vickers hardness exceeded HV350, and the evaluation result was also poor.

  In Experimental Example 18, the N content is larger than the range specified in the present invention. Therefore, the absorbed energy of all the deposited metals was insufficient, and the evaluation results were poor.

  In Experimental Example 19, the Si content is smaller than the range defined in the present invention, and the S content is larger than the range defined in the present invention. Therefore, the tensile strength and absorbed energy of all the deposited metals were insufficient, and the evaluation results were poor.

  In Experimental Example 20, the Mn content is smaller than the range defined in the present invention, and the Ni content is larger than the range defined in the present invention. Therefore, the tensile strength and 0.2% proof stress of all the deposited metals were insufficient, and the evaluation results were poor.

In Experimental Example 21, the Cr content is larger than the range specified in the present invention, and Ceq is also larger than the range specified in the present invention. Therefore, the tensile strength and Vickers hardness of all the deposited metals were high, and the evaluation results were poor.
In Experimental Example 22, the Mo content is larger than the range specified in the present invention. Therefore, the tensile strength and Vickers hardness of all the deposited metals were high, and the evaluation results were poor.
In Experimental Example 23, the Cr content, the V content, and the N content are larger than the ranges specified in the present invention. Therefore, the absorbed energy of all the deposited metals is insufficient, the Vickers hardness is high, and the evaluation result is poor.

  In Experimental Example 24, the C content is larger than the range specified in the present invention, and Ceq is also larger than the range specified in the present invention. Therefore, the tensile strength and Vickers hardness of all the deposited metals were high, and the evaluation results were poor.

  In Experimental Example 25, the P content is larger than the range specified in the present invention. Therefore, the absorbed energy of all the deposited metals was insufficient, and the evaluation results were poor. Moreover, there was much slag generation | occurrence | production amount and it was inferior to the external appearance.

DESCRIPTION OF SYMBOLS 1 Steel plate 1a Inclined surface 2 Groove 3 Backing material 4 Lower plate 5 Standing plate 6 Weld metal

Claims (4)

C: 0.02-0.06 mass%,
Si: 0.30-0.85 mass%, and Mn: 0.70-1.40 mass%,
Ni: 0.10% by mass or less (including 0% by mass),
Cr: 0.10 mass% or less (however, 0 mass% is included),
Mo: 0.10 mass% or less (however, 0 mass% is included),
V: 0.05 mass% or less (however, 0 mass% is included),
P: 0.030 mass% or less (however, 0 mass% is not included),
S: 0.030% by mass or less (excluding 0% by mass) and N: 0.0100% by mass or less (excluding 0% by mass), respectively,
The balance consists of Fe and inevitable impurities, and
The filler metal for TIG welding whose carbon equivalent Ceq represented by following formula (1) is in the range of 0.15-0.35.
Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14 (1)
(However, [C], [Si], [Mn], [Ni], [Cr], [Mo] and [V] are the contents of C, Si, Mn, Ni, Cr, Mo and V, respectively ( Mass%).)   The filler for TIG welding according to claim 1, wherein the carbon equivalent Ceq is in a range of 0.20 to 0.33. Al: 0.10% by mass or less (including 0% by mass),
Ti: 0.10% by mass or less (however, 0% by mass is included),
Zr: 0.10 mass% or less (however, 0 mass% is included), and O: 0.0100 mass% or less (however, 0 mass% is not included)
The filler material for TIG welding according to claim 1 or 2, further comprising at least one selected from the group consisting of and satisfying the relationship of the following formula (2).
[X] = ([Ti] + [Al] + [Zr]) × [O] × 10000 ≦ 10.0 (2)
(However, [Ti], [Al], [Zr], and [O] indicate the contents (mass%) of Ti, Al, Zr, and O, respectively.)   The filler material for TIG welding according to any one of claims 1 to 3, further containing Cu: 0.50 mass% or less (including 0 mass%).

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