JPH07204885A - Welding material of ferritic steel with excellent resistance to hot cracking - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent hot cracking in welding with high heat input. Even when applied to a ferritic steel with a high Cr content of 10% or more and high temperature and high strength and high temperature and corrosion resistance, it provides the welded portion with the same high temperature strength and corrosion resistance as the base metal. Prevents deterioration of the toughness of the weld. A uniform weld bead having a width dimension with few welding defects is formed. [Composition] C: 0.03 to 0.15% by weight, Si: 0.1% by weight.
1-0.8%, Mn: 0.5-2%, P: 0.02% or less,
S: 0.001 to 0.008%, Cr: 10 to 13%, N
i: 0.1 to 1.5%, Mo: 0.01 to 0.3%, W: 1 to 2.
5%, Nb: 0.02 to 0.2%, V: 0.05 to 0.3%, C
u: 3% or less, Al: 0.005 to 0.05%, N: 0.00
2 to 0.07%, O: 0.01% or less, and Cr +
4Si-8.5 ≦ 4Ni + Cu is satisfied, and the balance is based on a component system consisting of Fe and inevitable impurities. At least one of Y, Ce and La is 0.00 to prevent welding hot cracking.
1 to 0.01% is added. Alternatively, Nb: 0.002-0.0
2% + V: 0.05 to 0.3% or Nb: 0.02 to 0.2%
+ V: As a combination of 0.008 to 0.05%, the composite degree of Nb and V is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferritic steel welding material having excellent high temperature crack resistance, high temperature strength and corrosion resistance, which is used for welding high Cr ferritic steel excellent in strength and corrosion resistance at high temperatures.

[0002]

2. Description of the Related Art As high temperature materials used for heat resistant and pressure resistant piping for boilers and chemical industries, low alloy steel such as 2.1 / 4Cr-1Mo steel, high Cr ferritic steel such as 9Cr-1Mo steel, 18Cr-8Ni, etc. Three austenitic stainless steels represented by steel are well known. Above all,
High-Cr ferritic steel is not only cheaper than austenitic stainless steel, but also has a high resistance to stress corrosion cracking and a small coefficient of thermal expansion, so it is excellent as a high-temperature material with low strain with respect to temperature changes. It also has the advantage.

However, steels having a so-called ferritic structure such as ferrite, bainite and martensite are
Its strength at high temperatures is lower than that of steel having an austenitic structure.

Therefore, in recent years, the amount of Mo, the amount of W, the amount of V, the amount of Nb, the amount of Ni, based on 8 to 13% Cr type ferritic steel,
Excellent high temperature strength (creep strength) by adjusting the amount of Al, etc.
New high Cr ferritic steels have been developed one after another (Japanese Patent Laid-Open Nos. 61-231139 and 62-62).
297435, JP-A-2-232345,
JP-A-3-97832).

The welding materials required when these new high Cr ferritic steels are used as welded structures are also disclosed in JP-A-63-188492 and JP-A-63.
New proposals have been made in Japanese Patent Laid-Open No. 76789, Japanese Patent Laid-Open No. 5-177383 and Japanese Patent Laid-Open No. 5-177384. In addition to these new welding materials, commercially available 13Cr-based ferrite welding materials and austenitic high-Ni alloy welding materials may be used.

[0006]

[Problems to be Solved by the Invention] The newly developed high C
In r-ferritic steel, the Cr content is particularly increased when importance is attached to corrosion resistance at high temperatures. However, such high-temperature materials, especially high-strength and high-corrosion, high-Cr ferritic steel having a Cr content of 10% or more (for example, JP-A-2-232345).
However, when the above-mentioned known welding material is used, the following problems occur.

When a commercially available 13Cr-based ferrite welding material such as JIS Y430 is used, the high temperature strength of the welded portion is significantly reduced as compared with the base metal. When a commercially available welding material of austenitic high Ni alloy is used, hot cracking of the weld is likely to occur, and C in the base metal shifts to the side of the weld metal (high Ni alloy) during use at high temperature, resulting in a decarburized layer. Occurs and reduces the creep strength.

Newly proposed welding materials, for example, JP-A-63-188492 and JP-A-63-7678.
When the welding material disclosed in Japanese Patent Publication No. 9 is used, although the creep strength equivalent to that of the base material is obtained, when the Cr content in the welding material is less than 10%, the high temperature corrosion resistance of the weld metal is higher than that of the base material. Is inferior. To ensure high temperature corrosion resistance,
It is necessary to increase the Cr content to 10% or more and the Si content to 0.25% or more, but in that case, high impact toughness cannot be obtained in the weld metal. Since a relatively large amount of Mo is added to secure the creep strength, the toughness also decreases. Weldability is poor regardless of the amount of Cr. That is, the width of the weld bead varies greatly, and welding defects are likely to occur.

Also, when the welding materials disclosed in JP-A-5-177383 and JP-A-5-177384 are used, the creep strength is similarly secured, but the amount of Cr in the welding material is When less than 10%,
The high temperature corrosion resistance of the weld metal is inferior to that of the base metal. Since the high temperature crack resistance of welding is not sufficient, problems remain in high heat input TIG welding and submerged arc welding. Since Mo is added in a relatively large amount of 0.3 to 1.6% to secure the creep strength, it cannot be said that the toughness is sufficient. A weld bead with a uniform bead width that does not easily cause weld defects cannot be obtained.

An object of the present invention is to solve all of these problems and to provide a welded portion of high Cr ferritic steel excellent in strength and corrosion resistance at high temperature with high temperature strength and high temperature corrosion resistance comparable to those of the base metal. It is an object of the present invention to provide a ferritic steel welding material which can impart excellent welding high temperature cracking resistance and toughness and can also obtain a weld bead in which a welding defect is unlikely to occur and whose width variation is small.

[0011]

In the welding of high Cr ferritic steel excellent in strength and corrosion resistance at high temperature, in order to impart high temperature strength and high temperature corrosion resistance comparable to the base metal to the welded portion, high welding material It is considered that Cr and high Si are indispensable. However, when a high Cr, high Si welding material is used, as described above, the impact toughness of the weld, particularly the weld metal, is reduced.

The decrease in toughness associated with high Cr content and high Si content is generally prevented by adjusting the chemical structure so as not to form the residual ferrite phase, which is the main factor thereof. It is very difficult to materialize.

For example, by adding a large amount of Ni,
It is possible to suppress the formation of residual ferrite phase to form a martensite single phase, but excessive addition of Ni lowers the austenite transformation point, and austenite transformation occurs during post-welding heat treatment, resulting in a decrease in creep strength. Invite. Further, Cu has also been considered to be effective in suppressing the formation of residual ferrite phase, but its effect on high Cr ferrite-based weld metal was unknown.

What is decisively different from the base metal in the weld metal is that the weld metal is used as it is in the rapidly solidified structure without any structure adjustment by the hot working and heat treatment processes.

In consideration of this point, the present inventors scrutinized the effect of Ni and Cu in high Cr high Si ferritic steel. As a result, it has been found that the composite addition of Ni and Cu corresponding to the amounts of Cr and Si makes it possible to suppress the formation of residual ferrite phase in the weld metal and obtain stable toughness.

Nb and V are very important elements for ensuring the creep strength. However, it has been found that the composite addition forms a eutectic having a low melting point with C and Fe, and causes hot cracking in the welding. Therefore, in the case where these elements are compositely added at a normal level, at least one of rare earth elements Y, La, and Ce is added. Then, the weld hot cracking susceptibility is lowered without lowering the creep strength. Further, instead of adding the rare earth element, the degree of composite of Nb and V may be lowered. Even in that case, since the creep strength is increased by other means, the weld hot cracking susceptibility is lowered while securing the sufficient creep strength. Decrease in Nb and V compositeness means to reduce one of them. If both are reduced, the creep strength is lowered.

W and Mo as well as Nb and V are essential elements for obtaining high creep strength. However, none of these elements is preferable for toughness. It has been found that the limitation of Mo is particularly effective for suppressing the decrease in toughness. Even if Mo is limited, under the above-mentioned proper addition of Ni and Cu, high Cr and high S
Since i is effective in satisfying both the creep strength and the toughness, the decrease in creep strength due to the limitation is not a problem.

Regarding the uniformity of the weld bead width, the S content,
It was found that proper regulation of Si content and Al content is necessary.
That is, by keeping the S content and the Al content in appropriate ranges, the current path of the arc plasma is expanded, and the addition of Si enhances the fluidity of the oxide on the molten pool, which enables stable molten pool transfer. Therefore, the uniformity of the bead width is ensured.

The ferritic steel welding material of the present invention was developed on the basis of these findings, and it is
And C: 0.03 to 0.15%, Si: 0.1 to 0.8%, M
n: 0.5-2%, P: 0.02% or less, S: 0.001-0.
008%, Cr: 10-13%, Ni: 0.1-1.5%,
Mo: 0.01 to 0.3%, W: 1 to 2.5%, Nb: 0.02
~ 0.2%, V: 0.05-0.3%, Cu: 3% or less, A
1: 0.004 to 0.05%, N: 0.002 to 0.07%,
O: Contains 0.01% or less, and Cr + 4Si-8.5 ≦
It is based on a component system that satisfies 4Ni + Cu and the balance is Fe and inevitable impurities.

The ferritic steel welding material according to claim 1 further includes rare earth elements Y, Ce, La.
Of at least one of 0.001 to 0.01%. Further, the ferritic steel welding material according to claim 2,
Nb is reduced to 0.002 to 0.02% without adding a rare earth element, and the ferritic steel welding material according to claim 3 has V of 0.008 to 0.05 without adding a rare earth element. It has been reduced to%. These component operations are as described above.
This is for improving the high temperature weld crack resistance.

Further, in any of the welding materials, Mg 0.0005 to 0.1% or B 0.0001 to 0.01, as required.
% Can be added.

The ferritic steel (welding material) disclosed in Japanese Unexamined Patent Publication No. 5-177384 is 8 to 13% Cr and 0.1%.
Since it contains 05-1.2% Ni and 0.5-4% Cu, it can be used for welding ferritic steel with high temperature and high strength and high temperature and high corrosion resistance in which the amount of Cr is increased to 10% or more. It can be expected that the high temperature strength and high temperature corrosion resistance comparable to that of the material will be imparted to the welded portion, and at the same time, deterioration of the toughness of the weld metal can be prevented.

However, the total amount of Si is small, and it cannot be said that the high temperature corrosion resistance is sufficient. In addition, since no measures against welding hot cracking have been taken, there is a risk of welding hot cracking in high heat input welding. Further, since the amount of Mo is large and the amount of Ni and Cu commensurate with the amount of Cr and Si is not added, a sufficient and stable toughness improving effect cannot be obtained. Further, it is not possible to obtain a sufficient effect for making the bead width uniform.

[0024]

The function of each component in the welding material of the present invention and the reason for limiting the content will be described below.

C: 0.03 to 0.15% C combines with Cr, Mo, W, V and Nb to form a carbide, which contributes to the high temperature strength of the welded portion. Furthermore, as an austenite forming element, it contributes to the suppression of the formation of the δ ferrite phase. However, excessive addition of Cr, in the weld metal,
It forms a low melting point eutectic with Nb and V to cause hot welding cracking, and hardens martensite to cause welding cold cracking. Therefore, C is set to 0.03 to 0.15%. C
Desirable lower limit is 0.04%, more desirable lower limit is 0.05
%, The desirable upper limit is 0.13%, and the more desirable upper limit is 0.11%.

Si: 0.1 to 0.8% Si is an essential element for enhancing the oxidation resistance and high temperature corrosion resistance of the welded portion. Also, make the bead width uniform,
It also contributes to the improvement of welding workability. However, in the present invention, the addition of a large amount leads to a decrease in creep strength and a decrease in toughness after long-term use, accompanied by an increase in Ni and Cu. Therefore, S
i was 0.1 to 0.8%. Desirable lower limit of Si is 0.15
%, A more desirable lower limit is 0.2%, and a desirable upper limit is
0.6%, and a more desirable upper limit is 0.7%.

Mn: 0.5-2% Mn fixes S, and if it is 0.5% or more, it has an effect of suppressing harmful effects of S such as weld cracking and creep embrittlement. But 2
If it exceeds%, the weld metal becomes brittle. Therefore, Mn is 0.
It was set to 5 to 2%. The desirable lower limit of Mn is 0.6%, the desirable lower limit is 0.7%, the desirable upper limit is 1.8%, and the desirable upper limit is 1.6%.

P: 0.02% or less P is 0.02% or less because it causes heat embrittlement of the weld metal. No lower limit is set, but extremely low P is accompanied by a large increase in cost, so 0.002% or more is desirable, and 0.002% or more is desirable.
5% or more is more desirable. Also, the desirable upper limit of P is 0.
015%, and a more desirable upper limit is 0.01%.

S: 0.001 to 0.008% S was originally treated as an unavoidable impurity in steel, but it is effective in improving the fluidity of the weld metal in the molten state, and 0.001% in the welding material. You need more than that. However, 0.0
Addition of more than 08% causes a decrease in the uniformity of the bead width, which easily causes welding defects. Therefore, S is 0.001 to 0.
It was set to 008%. The desirable lower limit of S is 0.002%, the desirable lower limit is 0.003%, and the desirable upper limit is 0.0.
06%, and a more desirable upper limit is 0.005%.

Cr: 10 to 13% Cr is an essential element for ensuring the oxidation resistance and the high temperature corrosion resistance of the welded portion at high temperature (550 to 650 ° C). However, in the present invention, the addition of a large amount leads to a decrease in creep strength and a decrease in toughness after long-term use, accompanied by an increase in Ni and Cu. Therefore, Cr is set to 10 to 13%. The desirable lower limit of Cr is 10.5%, the desirable lower limit is 11%, the desirable upper limit is 12.5%, and the desirable upper limit is 12%.
%.

Ni: 0.1 to 1.5% and 4Ni + Cu ≧ C
r + 4Si-8.5 Ni requires 0.1% or more to improve the toughness of the matrix, preferably 0.6% or more, and more preferably 0.8% or more. Further, from the viewpoint of suppressing the formation of residual δ ferrite phase and ensuring toughness as a martensite single phase structure, C
An addition satisfying the above formula is required together with u. However, on the other hand, it lowers the austenite transformation temperature (Ac ₁ point) and causes austenite transformation during post-welding heat treatment, resulting in lower creep strength. Therefore, the upper limit is 1.5
%, 1.4% or less is desirable, and 1.2% or less is more desirable.

Mo: 0.01-0.3% Mo solid-solution strengthens the matrix and precipitates as fine carbides, contributing to creep strength. The effect is increased by the combined addition of W. But 0.01
If it is less than 0.1%, the effect is small, while if it exceeds 0.3%, the toughness decreases. Therefore, Mo is set to 0.01 to 0.3%. The desirable lower limit of Mo is 0.02%, the desirable lower limit is 0.04%, the desirable upper limit is 0.25%, and the desirable upper limit is 0.2%.

W: 1 to 2.5% W strengthens the matrix in a solid solution like Mo, and
Precipitates as fine carbide and contributes to creep strength.
The effect is increased by the combined addition with Mo. However, excessive addition of W deteriorates the toughness of the weld metal.
Therefore, W is set to 1 to 2.5%. The desirable lower limit of W is 1.1%, and the desirable lower limit is 1.2%.
A desirable upper limit is 2%, and a more desirable upper limit is 1.8%.

Nb: 0.02 to 0.2%, 0.002 to 0.02
% Nb forms Nb (C, N) and contributes to the improvement of creep strength. However, the precipitation of Nb (C, N) promotes hardening on the one hand and impairs toughness. Further, in the case of adding V in combination, welding hot cracking is caused. Therefore, from the viewpoint of reducing the degree of compositeness, when V is 0.008 to 0.05%, Nb
To a normal level of 0.02 to 0.2% and V of 0.05 to 0.3.
%, Nb was set to a low level of 0.002 to 0.02%. When a rare earth element described below is added,
V is set to a normal level of 0.05 to 0.3% and Nb is set to 0.02 to
As a normal level of 0.2%, a sufficient degree of complexity was secured.
When Nb is normal level, the desirable lower limit is 0.025%,
A more desirable lower limit is 0.03%, and a desirable upper limit is 0.03%.
19%, and a more desirable upper limit is 0.18%. Also, N
If b is low, a desirable lower limit is 0.0025%, a more desirable lower limit is 0.003%, and a desirable upper limit is 0.003%.
018%, and a more desirable upper limit is 0.015%.

V: 0.05-0.3%, 0.008-0.05% V forms V (C, N) and contributes to the creep strength, but excessive addition rather impairs the creep strength. . In addition, in the case of compound addition with Nb, high temperature welding cracking is caused.
Therefore, the normal level is set to 0.05 to 0.3% or the low level is set to 0.008 to 0.05% based on the degree of compositeness and the relationship with the rare earth element as described in Nb. When V is a normal level, a desirable lower limit is 0.055%, a more desirable lower limit is 0.06%, and a desirable upper limit is 0.25%.
A more desirable upper limit is 0.2%. When V is at a low level, a desirable lower limit is 0.01%, and a more desirable lower limit is
0.02%, a desirable upper limit is 0.045%, and a more desirable upper limit is 0.04%.

Cu: 3% or less and 4Ni + Cu ≧ Cr +
4Si-8.5 Cu suppresses the formation of residual δ ferrite phase by the combined addition of Ni and secures the toughness of the weld metal. However, excessive addition causes deterioration of toughness after long-term use. Therefore, C
u is not less than the above formula and not more than 3%. The desirable upper limit of Cu is
2.5%, and a more desirable upper limit is 2%.

Al: 0.004 to 0.05% Added as a deoxidizer. Excessive addition impairs weld bead width uniformity. Therefore, Al is 0.004 to 0.05%
And A desirable lower limit of Al is 0.005%, a more desirable lower limit is 0.006%, and a desirable upper limit is 0.04%,
A more desirable upper limit is 0.03%.

N: 0.005 to 0.07% N combines with Nb and V to precipitate a nitride and contributes to the creep strength. However, excessive addition causes coarsening of precipitates, which rather impairs creep strength. Therefore, N is
It was set to 0.005 to 0.07%. The desirable lower limit of N is 0.02
%, A more desirable lower limit is 0.03%, a desirable upper limit is 0.06%, and a more desirable upper limit is 0.05%.

O: 0.01% or less O remains in the weld metal as an oxide, leading to a decrease in toughness. In order to secure the toughness of the structure hardened by the addition of strengthening elements such as W, Nb, V and Mo, it is necessary to reduce the O content, and the content is made 0.01% or less. However, excessive reduction of O causes high cost. A desirable lower limit of O is 0.0005%, a more desirable lower limit is 0.001%, and a desirable upper limit is 0.0.
08%, and a more desirable upper limit is 0.007%.

Y, La, Ce: 0.001 to 0.01% These rare earth elements prevent an increase in weld hot cracking susceptibility when the degree of combination of Nb and V is increased. However, excessive addition impairs weldability. Therefore, Nb is 0.02 to 0.2
%, V is 0.05 to 0.3%, 0.001 to 0.01% of one or more of these elements is contained. The desirable lower limit of these elements is 0.002%, and the more desirable lower limit is 0.00
3%, a desirable upper limit is 0.009%, and a more desirable upper limit is 0.008%.

Mg: 0.0005 to 0.1% Mg is effective in improving the hot workability when processing into a wire and is expected to have the effect of fixing S, so Mg may be added. However, excessive addition reduces the cleanliness of the weld metal. Therefore, if added, 0.0005-0.1%
And A desirable lower limit of Mg is 0.001%, a more desirable lower limit is 0.005%, and a desirable upper limit is 0.08%,
A more desirable upper limit is 0.06%.

B: 0.0001 to 0.01% B may be added because it has the effect of dispersing and stabilizing the carbide and increasing the creep strength by adding a trace amount. When adding, it is 0.0001 to 0.01%. Excessive addition impairs processability. The desirable lower limit of B is 0.0005%, the desirable lower limit is 0.001%, and the desirable upper limit is 0.005%.
008%, and a more desirable upper limit is 0.006%.

[0043]

EXAMPLES Next, examples of the present invention will be shown, and the effects of the present invention will be clarified by comparison with comparative examples.

Outer diameter 300 mm × wall thickness 4 made of high Cr ferritic steel having the chemical composition shown in Table 1 and having a Cr content of 10% or more.
A 0 mm steel pipe and a steel pipe having an outer diameter of 200 mm and a thickness of 20 mm were used as base materials. A groove was provided in each base material, and circumferential welding was performed by TIG welding and submerged arc welding using various welding materials. This ferritic steel is 600 ° C-1
It has a high creep strength of about 17 kgf / mm ^{2 for} 10,000 hours, and has high oxidation resistance and high temperature corrosion resistance.

Table 3 shows the chemical composition of the welding material used for welding.
~ Shown in Table 6. All of the welding materials are wires having an outer diameter of 2.4 mm, which are manufactured by the processes of melting hot working and wire drawing. The welding condition is that the heat input is 25,000 with TIG welding.
J / cm, 30,000 J / cm by submerged arc welding
It was set so that After welding, post-weld heat treatment was performed at 740 ° C. Table 2 shows the chemical composition of the flux used for submerged arc welding.

The weld bead width of the obtained welded joint was measured, and the bending test piece, the Charpy impact test piece, the creep test piece and the corrosion resistance test piece shown in FIG. 1 were sampled from the joint, and each test piece was side-bent. The test, the Charpy impact test at 0 ° C., the creep test at 600 ° C., and the high temperature oxidation test were each performed.

In the side bending test, the test piece was bent 180 degrees at a bending radius twice the plate thickness, and the presence or absence of high temperature welding cracks in the welded metal portion was examined.

In the creep test, the high Cr ferritic steel as the base material is 5000 to 6000 h, and the general-purpose steel ASME
Stress of T91 steel showing a breaking life of about 100 h 18.5 kg
f / mm ² is added, and the breaking life is less than 4000h x 4
000h or more was marked with ◯.

In the high temperature oxidation test, 700 ° C. in steam
After heating for 1000 hours and measuring the scale thickness of the surface, the high temperature oxidation resistance as a boiler material was evaluated. The scale thickness of the base material in the same test was 80 μm.

Tables 7 to 9 show the results of each test and the results of investigating the variation rate of the bead width.

Nos. 1 to 15 are welding materials A1 to A of the present invention.
No. 15 to 15 are used for large heat input TIG welding (25000 J / cm), Nos. 16 to 30 are welding materials A1 to A15 of the present invention.
Is an example in which is used for submerged arc welding (30000 J / cm). It was confirmed that welding hot cracking did not occur in all the weld metal parts and that the welding material of the present invention was excellent in welding hot crack resistance. Further, although the base material was high in Cr and high in Si, creep strength and high temperature corrosion resistance comparable to those of the base material were obtained, and excellent toughness was also obtained. Furthermore, a weld bead with less fluctuation in width, which is unlikely to cause welding defects, was obtained.

On the other hand, Nos. 31 to 34 are examples in which comparative welding materials B1 to B4 were used for high heat input TIG welding. Since neither of the welding materials took measures against the decrease in the composite degree of Nb and V and the addition of rare earth elements, the welding hot crack resistance was not good.

Welding material B5 used for Nos. 35-37
Since B7 had a large amount of Mo, sufficient toughness could not be secured. B8 and B9 used in No. 38 and 39 are C
Since addition of Ni and Ca commensurate with the amounts of r and Si was not made, sufficient toughness could not be secured. In B10 used in No. 40, Ni was excessively added, and therefore sufficient toughness could not be secured.

In No. 41 using B11, the high temperature corrosion resistance was not good because Si in the welding material was insufficient. In No. 42 using B12, the welding material Cr
Since the amount was small, the high temperature corrosion resistance was still poor.
In Nos. 43 and 44 using B13 and B14, since the S content and the Al content in the welding material were not limited, the bead width variation was large.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

[0058]

[Table 4]

[0059]

[Table 5]

[0060]

[Table 6]

[0061]

[Table 7]

[0062]

[Table 8]

[0063]

[Table 9]

[0064]

As is apparent from the above description, the ferritic steel welding material of the present invention suppresses high temperature weld cracking in large heat input welding, which is a problem when Nb and V are added in combination.
Even when applied to ferritic steel with high-temperature high-strength and high-temperature high-corrosion resistance with a Cr content of 10% or more, it imparts high-temperature strength and high-temperature corrosion resistance comparable to that of the base metal to the weld to prevent deterioration of the toughness of the lap weld. You can In addition, it is possible to form a weld bead with a small fluctuation in width and prevent welding defects.

[Brief description of drawings]

FIG. 1 is a dimensional diagram of a test piece used for a performance test of a welded portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Matsumoto 1-17 Fuso-cho Amagasaki-shi Hyogo Sumikin Welding Co., Ltd. (72) Toshihiko Mizuta 1-17 Fuso-cho Amagasaki-shi Hyogo Sumikin Welding Within Kogyo Co., Ltd.

Claims (5)

[Claims] 1. C: 0.03 to 0.15% by weight, S
i: 0.1 to 0.8%, Mn: 0.5 to 2%, P: 0.02% or less, S: 0.001 to 0.008%, Cr: 10 to 13%,
Ni: 0.1 to 1.5%, Mo: 0.01 to 0.3%, W: 1 to
2.5%, Nb: 0.02 to 0.2%, V: 0.05 to 0.3%,
Cu: 3% or less, Al: 0.004 to 0.05%, N: 0.0
02-0.07%, O: 0.01% or less, Y, Ce,
Welding hot cracking resistance characterized by containing 0.001 to 0.01% of at least one kind of La and satisfying Cr + 4Si-8.5 ≦ 4Ni + Cu, with the balance being Fe and inevitable impurities. Excellent ferritic steel welding material. 2. C: 0.03 to 0.15% by weight, S
i: 0.1 to 0.8%, Mn: 0.5 to 2%, P: 0.02% or less, S: 0.001 to 0.008%, Cr: 10 to 13%,
Ni: 0.1 to 1.5%, Mo: 0.01 to 0.3%, W: 1 to
2.5%, Nb: 0.002 to 0.02%, V: 0.05 to 0.3
%, Cu: 3% or less, Al: 0.004 to 0.05%, N:
0.002 to 0.07%, O: 0.01% or less, and
Cr + 4Si-8.5 ≦ 4Ni + Cu is satisfied, and the balance is F
A ferritic steel welding material excellent in weld hot cracking resistance, which is characterized by comprising e and inevitable impurities. 3. C: 0.03 to 0.15% by weight, S
i: 0.1 to 0.8%, Mn: 0.5 to 2%, P: 0.02% or less, S: 0.001 to 0.008%, Cr: 10 to 13%,
Ni: 0.1 to 1.5%, Mo: 0.01 to 0.3%, W: 1 to
2.5%, Nb: 0.02 to 0.2%, V: 0.008 to 0.05
%, Cu: 3% or less, Al: 0.004 to 0.05%, N:
0.002 to 0.07%, O: 0.01% or less, and
Cr + 4Si-8.5 ≦ 4Ni + Cu is satisfied, and the balance is F
A ferritic steel welding material excellent in weld hot cracking resistance, which is characterized by comprising e and inevitable impurities. 4. A ferritic steel welding material which is excellent in welding hot cracking resistance and further contains Mg: 0.0005 to 0.1% in addition to the components described in claim 1, 2 or 3. 5. A ferritic steel welding material which is excellent in weld hot cracking resistance and further contains B: 0.0001 to 0.01% in addition to the components of claim 1, 2 or 3.