JP3454354B2 - Austenitic / ferritic duplex stainless steel welding material and method for welding high Cr steel using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high Cr type stainless steel having high strength and high corrosion resistance, that is, 0.03% by weight of C.
When welding a steel containing 7 to 27% by weight of Cr (hereinafter, the weight% indicating the content of the chemical composition is simply referred to as “%”), a pre-heat treatment of the base metal and a heat treatment after welding are performed. TECHNICAL FIELD The present invention relates to an austenite / ferrite-based duplex stainless steel welding material that does not cause weld cracking, especially delayed cracking that occurs even after welding, and a welding method for high Cr stainless steel using the same.

[0002]

2. Description of the Related Art In recent years, along with the severer development conditions in oil fields,
As a steel pipe for oil well pipes and line pipes used there,
Austenite / ferrite duplex stainless steel or 13% Cr martensitic stainless steel, which has good corrosion resistance and strength, has come to be used. In particular, the latter 13% Cr martensitic stainless steel can be welded without preheating before welding and heat treatment immediately after welding (hereinafter referred to as "post heat treatment") due to the reduction of C and other improvements. It was

For example, it is highly preferable that welding can be carried out at the site of laying a line pipe without preheating or post heat treatment. However, recently, cracks (delayed cracks) that occur after a certain time has elapsed from the welding of joints of the above steel types that have been welded without heat treatment.

The phenomenon of delayed cracking (delayed fracture) in high strength steel has been known for a long time. This phenomenon is considered to be due to hydrogen embrittlement due to diffusible hydrogen. In particular, in the welded joint part, a portion having a high welding residual stress in a fusion line (hereinafter referred to as a bond) and a weld heat affected zone (hereinafter referred to as a HAZ), which is a boundary portion between a weld metal and a base metal, is a diffusible hydrogen trap site. Therefore, delayed cracking is likely to occur.

In order to prevent delayed cracking of the welded joint,
Conventionally, the weather at the time of welding construction is selected (for example, the welding operation is stopped during rainfall), the welding material is baked immediately before welding to remove water, and the water and oil in the weld groove are removed. Furthermore, measures have been taken to prevent hydrogen from entering the weld metal, such as employing gas shielded arc welding methods such as TIG or MIG welding using bare welding rods or wires with low hydrogen potential.

In addition to these, a method of reducing the cooling rate of the weld metal portion by pre-heating to promote hydrogen release from the weld metal portion, and a dehydrogenation of the weld metal portion by performing heat treatment immediately after welding Measures such as a method for preventing hydrogen accumulation at the trap site such as, are also effective.

However, in order to completely prevent the occurrence of delayed cracking in the welding of the above-mentioned high Cr type stainless steel,
Is not sufficient. Further, the heat treatments of and are not preferable in the welding of the base metal, which is advantageous in that such heat treatment is not necessary.

For the welding of these high Cr type stainless steels, if a welding material of stainless steel such as Y309L specified in JIS or austenitic Ni base superalloy such as YNiCr-3 is used, preheating Also, delayed cracking can be prevented without performing post heat treatment. The reason for this is that the weld metal formed of these welding materials has a face-centered cubic austenite structure, and the solid solution limit of hydrogen is large in that structure, and the diffusion coefficient of hydrogen is small. It is believed that this is because the diffusion of hydrogen into the bonds and HAZ hardly occurs. However, the austenitic welding material as described above has a relatively low strength and has a drawback that only a welded joint having an undermatching can be obtained as compared with the base material of the high Cr stainless steel.

[0009]

In order to increase the strength of a welded joint, a welding material of duplex stainless steel having both corrosion resistance, toughness and strength may be used. However, as compared with the above austenitic welding materials, this has a small austenite phase amount ratio of about 1/2, and as described above, the effect of preventing diffusion of hydrogen into the bonds and HAZ possessed by the austenitic structure is halved. May cause cracking.

A first object of the present invention is a welding material for high strength, high corrosion resistance, low C, high Cr stainless steel, in which delayed cracking occurs even if welding is performed without preheating and post heat treatment. Not to provide an austenitic / ferritic duplex stainless steel welding material.

A second object of the present invention is to provide a welding method using the above-mentioned welding material to obtain a welded joint of high Cr stainless steel which does not cause delayed cracking without performing preheating and post heat treatment. is there.

[0012]

The present inventors have found that low C and high
Using a duplex stainless steel solid wire as a base material of Cr stainless steel, TIG welding was performed without preheating, and the occurrence of delayed cracking was investigated without performing heat treatment immediately after welding.

As a result, the occurrence of delayed cracking in the welded joint is prevented by setting the hydrogen content in the steel of the welding material (wire) within an appropriate range according to the amount of ferrite (volume%) in the weld metal or weld metal. The inventors have found out what can be done and have completed the present invention.

The gist of the present invention resides in the following welding material (1) and the following welding method (2) using the welding material.

(1)% by weight, C: 0.03% or less, Cr: 7 to 2
A welding material for gas shielded arc welding of stainless steel containing 7%, in which the hydrogen content (Hw, ppm) in steel of the welding material and the amount of ferrite in the weld metal of the welding material (δd, where The product with δd ≧ 30% by volume is (1)
Austenitic / ferritic duplex stainless steel welding material that satisfies the formula.

Hw × δd ≦ 135 (1) The above welding materials are C: 0.08% or less, Si: 1.0% or less, M
n: 2.5% or less, P: 0.03% or less, S: 0.02% or less, Cr:
It is desirable to have a chemical composition containing 18 to 27%, Ni: 5 to 11%, Mo: 4% or less, W: 2.5% or less, N: 0.35% or less, and the balance being Fe and inevitable impurities.

(2) Weight%, C: 0.03% or less, Cr: 7 to 2
Stainless steel containing 7%, C: 0.08% or less, Si: 1.0%
Below, Mn: 2.5% or less, P: 0.03% or less, S: 0.02% or less, Cr: 18 to 27%, Ni: 5 to 11%, Mo: 4% or less, W:
Using a welding material containing 2.5% or less and N: 0.35% or less, and the balance being Fe and inevitable impurities, the amount of ferrite (δ
w, where δw ≧ 30% by volume) and the hydrogen content (Hw, ppm) in the steel of the above welding material are adjusted so that the product satisfies the following formula (2): Gas shielded arc welding method for stainless steel.

Hw × δw ≦ 154 (2) The material to be welded (base steel) to be welded using the welding material of the present invention is “weight%, C: 0.03% or less, Cr: Stainless steel containing 7 to 27%. " This base material steel is roughly classified into martensitic stainless steel and austenite-ferrite duplex stainless steel.

The former typical steel has a Cr content of 10.5 to 14%.
There is a so-called super martensitic steel containing about 2 to 6% Ni and about 2.5% or less Mo. 50
Strictly speaking, some steels have a volume% or less of ferrite and should be strictly called martensitic / ferritic steels, but including them, they are called martensitic stainless steels here.

The latter representative one is JIS SUS329J3.
L, same SUS329J4L duplex stainless steel, and JIS JIS SUS
There is a so-called super duplex stainless steel in which the contents of N and Mo are increased in 329J4L and alloys such as W are added to further improve corrosion resistance. For example, JP-A 8-260101 proposes an improved material of this type of steel.

Any of the above base steels has high strength and excellent corrosion resistance, and is suitable as a material for oil wells such as line pipes exposed to a corrosive environment containing hydrogen sulfide and carbon dioxide.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors used a martensitic stainless steel (reference numeral B1 in Table 1 below) and a preheat treatment using a duplex stainless steel solid wire (reference numeral W5 in Table 1 below). TIG welding without applying
Immediately after welding, when heat treatment was not performed and left for 168 hours, delayed cracking was observed.

Delayed cracking of the welded joint is cracking due to hydrogen. The crack involves the material factors of the weld metal and the base steel, and the residual stress generated after welding. Particularly large influence is diffusible hydrogen in the weld metal portion that enters during welding.

Then, the hydrogen content in the steel of the above duplex stainless steel solid wire and the diffusible hydrogen content in the weld metal part were measured. As a result, the hydrogen content in the steel was 6.6 ppm, and the diffusible hydrogen content was 1.99 ml / It was 100 gr. This was at a much higher level, whereas the amount of diffusible hydrogen when the conventional austenitic stainless steel wire was used was undetectable. This is for the following reason.

The microstructure of the weld metal portion formed of the duplex stainless steel welding material naturally exhibits a dual phase structure consisting of a ferrite phase and an austenite phase. For more information,
This two-phase structure is a structure in which the austenite phase generated by solid phase transformation is dispersed in the matrix of the ferrite phase. Therefore, the diffusion mode of hydrogen in duplex stainless steel is
Since it is largely controlled by the characteristics of the matrix (ferrite phase), it is more similar to the diffusion morphology in ferritic stainless steel than in austenitic stainless steel. That is, in the weld metal part of the duplex stainless steel, hydrogen diffuses and migrates like the ferrite single-phase steel.

As described above, since the solid solubility limit of hydrogen in the austenite phase is large and its diffusion coefficient is small,
Diffusible hydrogen that causes delayed cracking is mainly derived from hydrogen existing in the ferrite phase. Bond or HAZ when hydrogen potential in ferrite phase is high
It is considered that hydrogen diffuses and accumulates at the trap site (stress concentration part) of and causes delayed cracking.

However, in the same manner as the austenitic steel wire, the duplex stainless steel wire is subjected to solution heat treatment at about 1100 ° C. (generally called bright annealing in order to remove strain generated during wire drawing and improve the structure. ) Is given. This heat treatment is performed in a reducing gas atmosphere to prevent wire oxidation,
For example, it is carried out in an ammonia decomposition gas (gas containing about 75% by volume of hydrogen and about 25% by volume of nitrogen) or a pure hydrogen gas atmosphere. Hydrogen in this atmosphere gas penetrates into the wire during the heat treatment. Therefore, the more the bright annealing is performed on the wire, and the smaller the diameter is, the more hydrogen is absorbed,
The amount of dissolved hydrogen (hydrogen content in steel) increases. As described above, it was confirmed that the conventional duplex stainless steel wire has a substantially same dissolved hydrogen content (hydrogen content in steel), but a high diffusible hydrogen content, like the austenitic steel wire.

The inventor of the present invention conducts the tests shown in Examples to be described later in order to quantify the relationship between the hydrogen content in the steel of the welding material and the diffusible hydrogen in the weld metal and the relationship between them and delayed cracking. It was

FIG. 1 is a diagram showing the relationship between the ratio of the amount of diffusible hydrogen in the weld metal to the hydrogen content in the steel of the welding material and the amount of ferrite in the weld metal. This figure shows that the ratio of the diffusible hydrogen (Hd) in the weld metal part to the hydrogen content (Hw) in the steel of the welding material (Hd /
FIG. 4 is a diagram in which Hw) is plotted on the vertical axis and the ferrite amount (Δw) of the weld metal part is plotted on the horizontal axis. From this figure, the diffusible hydrogen content (Hd) of the weld metal and the hydrogen content (Hw) in the steel of the welding material
And the ratio (Hd / Hw) is the amount of ferrite in the weld metal (δ
It was found that it increased almost linearly with respect to w), and
The relationship of equation (a) was obtained.

Hd = Hw × 0.0046 × δw (ppm) (a) Next, a y-type weld cracking test using the same 13Cr-based high-strength martensitic stainless steel and duplex stainless steel as base materials ( From the results of JIS Z3158), the effects of the amount of ferrite in the weld metal, the amount of diffusible hydrogen and the hydrogen content in the steel of the welding material on the delayed weld cracking were investigated.

FIG. 2 is a diagram showing the influence of the ferrite content of the weld metal and the hydrogen content in the steel of the welding material on the delayed weld cracking. In the figure, ○ and ● marks are when 13Cr high strength martensitic stainless steel is used as the welding base metal, and □ and ■ marks are when duplex stainless steel is used as the welding base metal. O and □ marks indicate that no cracks were observed in the y-type weld cracking test, and ● and ■ marks indicate that cracks were observed in the y-type weld cracking test. As is clear from FIG. 2, the curve A can be used to stratify the cracks observed and the cracks not observed. This curve A
As a result of various attempts to identify, the relation graph of the reciprocal number (1 / δw) of the ferrite amount δw of the weld metal and the hydrogen content Hw in the welding material as shown in FIG. It was found that the straight line in equation (b) can be used for stratification.

1 / δw = Hw / 154 (b) By modifying this equation (b), the following equation (2) is obtained.

Hw × δw ≦ 154 (2) That is, if the product of the ferrite amount δw of the weld metal and the hydrogen content Hw in the steel of the welding material is smaller than 154, delayed cracking after welding It can be seen that this can be prevented.

Strictly speaking, the weld metal portion formed by using the above-mentioned welding material must have a two-phase structure in which the amount of ferrite is 30% by volume or more. If the amount of ferrite is less than 30% by volume, it belongs to the category of austenitic stainless steel in a broad sense such as Y309MoL of JIS, and the advantage of duplex stainless steel in high strength is lost. The upper limit of the amount of ferrite is preferably about 75% by volume.

The amount of ferrite in the weld metal part is calculated by calculating Ni equivalent and Cr equivalent from the chemical composition of the welding material, for example, Es
py diagram (ASME Sec.II Part C SFA 5.9 Appendix Fig.A
It can be roughly predicted from 2). However, if the welding material contains components that are not included in the Ni equivalent and Cr equivalent formulas used in these figures, it is difficult to predict. Also,
The cooling rate due to welding conditions also has a large effect on the ferrite content. Therefore, the strict amount of ferrite in the weld metal is
It is desirable to actually measure by the method using the microscopic structure specified in JIS Z3119. Depending on the ferrite amount ratio,
The hydrogen content H in the welding material steel so that the formula (2) is satisfied.
Adjust w.

The reduction of the hydrogen content in the steel of the welding material can be achieved, for example, by performing the final bright annealing in a vacuum heating furnace instead of in the conventional heating in an ammonia decomposition gas atmosphere or pure hydrogen gas. . Welding material (wire)
Since the attached water is evaporated by the heat generation of the wire during the welding work, it hardly affects the hydrogen content in the steel. However, it is naturally desirable to prevent the wire from damp and prevent it from getting wet during welding.

Furthermore, when the relationship between the ferrite content δd of the deposited metal and the hydrogen content Hw in the steel which the welding material originally must have to satisfy the formula (2) was investigated, as shown in FIGS. 4 and 5, To reduce the susceptibility to delayed cracking, the amount of δd and H
The smaller the product of w amount, the better. It is necessary to secure at least 135 or less.

Hw × δd ≦ 135 (1) Next, a desirable composition of the welding material will be described.

C: C is an element which stabilizes the austenite phase like N described later. However, if its content exceeds 0.08%, carbides are likely to precipitate, and the pitting corrosion resistance of the weld metal part deteriorates. Therefore, the C content is 0.08%
The following is desirable. More desirable is 0.03% or less.

Si: Si is used as a deoxidizing element when the welding material is melted. However, during welding, the intermetallic compound (σ
Phase) and reduces the toughness of the weld metal. Therefore, the upper limit should be 1.0%. The lower limit may be the impurity level, but it is 0 to secure the effect of deoxidation.
1% or more is desirable.

Mn: Mn is used as a deoxidizing element during melting of the welding material, and also combines with S to improve hot workability,
Further, it is an element that increases the solubility of N. But Mn
If the content exceeds 2.5%, the pitting corrosion resistance of the weld metal part is reduced. Therefore, its content is preferably 2.5% or less.
The lower limit is preferably 0.2% or more in order to secure the effect of deoxidation.

P: P is an impurity element which is inevitably mixed during the melting of the welding material, and the smaller the content, the more desirable. If the content exceeds 0.03%, the pitting corrosion resistance and toughness of the weld metal deteriorate significantly, so the content should be 0.03% or less.

S: S, like P, is an element that is inevitably mixed during the melting of the welding material, and the smaller the content, the better. S deteriorates the hot workability of steel, makes it difficult to perform the rolling process into a wire rod, and becomes a sulfide to become a starting point of pitting corrosion.
Impairs pitting corrosion resistance of weld metal. Therefore, its content is 0.
It should be below 02%.

Ni: Ni stabilizes the austenite phase,
It is an important element that adjusts the balance between the austenite phase and the ferrite phase of the weld metal. However, its content is 5
If it is less than 100%, the ferrite phase becomes more than 75% and an appropriate phase balance cannot be obtained. However, if the Ni content exceeds 11%, precipitation of σ phase is promoted during welding, resulting in a decrease in toughness.
Therefore, the content is preferably in the range of 5 to 11%.

Cr: Cr is an element that enhances corrosion resistance. If the content is less than 18%, the same corrosion resistance of the weld metal as the base metal cannot be obtained. However, excessive Cr promotes the precipitation of intermetallic compounds (σ phase etc.), and deteriorates the workability during wire processing. Further, the toughness is reduced by precipitating a σ phase in the weld metal portion during welding. Therefore, the content is preferably in the range of 18 to 27%.

Mo: Mo is an element which improves the pitting corrosion resistance of the weld metal part, like Cr. However, Mo content is 4.0%
If it exceeds, the action of facilitating the precipitation of intermetallic compounds is strong like Cr, which causes embrittlement of the raw material during manufacturing, and makes wire processing difficult. In addition, during welding, precipitation of σ phase is promoted in the weld metal portion, which causes embrittlement of the joint portion. Therefore, its content is preferably 4% or less. Especially when it is added to enhance pitting corrosion resistance and crevice corrosion resistance, its content should be 2.
It is desirable to set it to 0 to 4.0%.

W: W is an element that improves the corrosion resistance of the weld metal part, especially the resistance to pitting corrosion and crevice corrosion, similar to Mo, and is a stable oxide that does not reduce the pitting corrosion resistance even in a low pH environment. To form. Also, it is an element that improves pitting corrosion resistance like Cr, Mo and N.
The effect of promoting the precipitation of phases is relatively small. That is, Cr,
It is possible to increase the pitting corrosion resistance by reducing the Mo content. Therefore, W can be added if necessary, and when it is added, its content is preferably 1.5% or more. However, the effect is saturated even if the content exceeds 2.5%.

N (Nitrogen): N forms austenite and improves pitting corrosion resistance. When a large amount of ferrite-forming elements such as Cr and Mo are contained in the welding material of the present invention, the N content is 0.12 in order to make the balance between the ferrite phase and the austenite phase of the weld metal part proper. It is desirable to set it to be at least%. Furthermore, N is Cr, Mo
And, like W, improve pitting corrosion resistance. But 0.35
%, Blowhole defects occur in the weld metal. Further, the toughness and corrosion resistance of the weld metal part are deteriorated due to the formation of nitrides due to the heat effect during welding. Therefore,
The upper limit of N content should be 0.35%.

[0049]

[Example] Using a 13Cr high-strength martensitic stainless steel and a duplex stainless steel (both API-X80 grade) shown in Table 1, a y-type weld cracking test plate (plate thickness: according to JIS Z3158) 25 mm, root gap: 2 mm) was prepared. Further, as shown in Table 2, an austenite / ferrite type duplex stainless steel wire (diameter = 1.2 mm) having a changed amount of hydrogen was automatically fed and a 1 pass bead was welded by the TIG welding method.

The wire was subjected to solution heat treatment in a hydrogen gas atmosphere to increase the hydrogen content in the steel, and dehydrogenation heat treatment was performed in a vacuum atmosphere to reduce the hydrogen content in the steel. . In addition, the hydrogen content in steel of the wire is obtained by washing the wire with an organic solvent such as acetone in advance and then heating it in an inert gas, and detecting the hydrogen released at that time using gas chromatography (inert Gas extraction / dissolution-column decomposition-heat conduction method). Thus measured is the total amount of hydrogen dissolved in the wire (hydrogen content in steel). In addition, each wire was used to form a deposited metal on the surface of austenite-ferrite duplex stainless steel, and the amount of ferrite was measured from the microstructure, and the results are shown in Table 2.

[0051]

[Table 1]

[0052]

[Table 2]

The welding was performed without any pre-heat treatment and immediate heat treatment, and the welding conditions were set as follows.

Welding current: 180 A, Arc voltage ・ ・ ・ 14V, Welding speed: 10 cm / min, Wire feeding speed ... 8g / min, Atmosphere: Temperature 20 ° C, relative humidity 60%.

Shield gas (including back shield)
Used a first-grade argon gas according to JIS K 1105.
The gas flow rate of the welding torch was 10 liters / min, and the gas flow rate of the back shield was 5 liters / min.

The diffusible hydrogen content (Hd), the ferrite content (δw) and the delayed cracking of the weld metal portion of the obtained welded portion were investigated and shown in Table 3.

[0057]

[Table 3]

The amount of diffusible hydrogen (Hd) was measured by a gas chromatograph method specified in JIS Z3118.

Ferrite amount δw (volume%) of the weld metal part
Was measured from the microscopic structure.

To evaluate delayed cracking, the welded test piece was kept at room temperature for 168 hours, and then cracking in the cross section was observed. The case where no crack was observed was shown as pass (none), and the case where crack was observed was shown as fail (present).

From Table 3, in Test Nos. 1 to 9 of the present invention, the product (Hw × δw) of the hydrogen content Hw (ppm) in the steel of the welding material and the ferrite amount δw (volume%) of the weld metal part was obtained. Left side of equation (2) 154
It became the following, and delayed cracking was not recognized.

On the other hand, test numbers 10 to 15 of Comparative Examples
Indicates that the product (Hw x δw) of the hydrogen content Hw (ppm) in the welding material and the ferrite amount δw (volume%) in the weld metal exceeds 154, and delayed cracking is observed in the base metal HAZ or bond. It was This is because the amount of diffusible hydrogen in the weld metal increased.

[0063]

INDUSTRIAL APPLICABILITY The welding material of the present invention has a hydrogen content in steel equal to or lower than the allowable upper limit value calculated according to the ferrite content of the deposited metal (the product of the hydrogen content in steel of the welding material and the ferrite content). Is less than 135). By using this welding material, it is possible to prevent the occurrence of delayed cracking in gas shielded arc welding of high-strength, high-corrosion-resistant, high-Cr stainless steel without performing preheat treatment and immediate heat treatment.
Further, since the welding method of the present invention uses the welding material in which the hydrogen content in the steel is adjusted according to the amount of ferrite in the weld metal part, the occurrence of delayed cracking can be prevented without performing preheat treatment and immediate heat treatment.

As a result, the welding method of the present invention can be effectively used for on-site welding of oil country tubular goods and line pipes that are difficult to perform preheat treatment and immediate heat treatment.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the ratio of the amount of diffusible hydrogen in the weld metal to the hydrogen content in the steel of the welding material and the amount of ferrite in the weld metal.

FIG. 2 is a diagram showing influences of a ferrite content of a weld metal part and a hydrogen content in steel of a welding material on a delayed welding crack.

FIG. 3 is a diagram showing the relationship between the reciprocal of the amount of ferrite in the weld metal and the hydrogen content in the steel of the welding material.

FIG. 4 is a diagram showing influences of a ferrite content of a deposited metal and a hydrogen content in steel of a welding material on a delayed welding crack.

FIG. 5 is a diagram showing the relationship between the reciprocal of the amount of ferrite in the deposited metal and the hydrogen content in steel of the welding material.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Soyasu Tsukamoto 1-17 Fuso-cho Amagasaki-shi Hyogo Sumikin Welding Co., Ltd. (56) Reference JP-A-8-260101 (JP, A) JP-A 8-90281 (JP, A) JP 59-218295 (JP, A) JP 57-154395 (JP, A) JP 9-94694 (JP, A) JP 6-155080 (JP, A) JP-A-59-163097 (JP, A) International Publication 97/12072 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 35/30 B23K 9/14-9 / 235

Claims (3)

(57) [Claims] 1. By weight%, C: 0.03% or less, Cr: 7 to 27%
Is a welding material for gas shielded arc welding of stainless steel containing, and the hydrogen content (Hw, ppm) in the steel of the welding material and the amount of ferrite in the weld metal of the welding material (δd, where δd ≧ Austenite / ferrite type duplex stainless steel welding material characterized by satisfying the following equation (1) with the product (30% by volume). Hw × δd ≦ 135 (1) 2. The chemical composition in% by weight, C: 0.08% or less, S
i: 1.0% or less, Mn: 2.5% or less, P: 0.03% or less, S:
Claims characterized by comprising 0.02% or less, Cr: 18 to 27%, Ni: 5 to 11%, Mo: 4% or less, W: 2.5% or less, N: 0.35% or less, and the balance Fe and inevitable impurities. Item 2. An austenitic / ferritic duplex stainless steel welding material according to Item 1. 3. By weight%, C: 0.03% or less, Cr: 7 to 27%
A method of gas shield arc welding stainless steel containing C, 0.08% or less, Si: 1.0% or less, Mn: 2.5%
Below, P: 0.03% or less, S: 0.02% or less, Cr: 18-27
%, Ni: 5 to 11%, Mo: 4% or less, W: 2.5% or less,
N: 0.35% or less is used, and the balance is Fe and inevitable impurities are used as the welding material, and the amount of ferrite in the weld metal part of the welded joint formed by it (δw, where δw
≧ 30% by volume and hydrogen content (Hw, p in steel of the above welding materials)
pm) is adjusted so as to satisfy the following formula (2), a gas shielded arc welding method for high Cr stainless steel. Hw × δw ≦ 154 (2)