JP2006075853A - Laser-welded joint of austenitic alloy steel and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser-welded joint of an austenitic alloy steel having strength and creep strength equal to those of a base material, and to provide its production method. <P>SOLUTION: The laser-welded joint is composed of an austenitic alloy steel having a composition comprising, by mass, ≤0.2% C, ≤2% Si, ≤3% Mn, ≤0.03% P, ≤0.01% S, 15 to 35% Cr, 6 to 45% Ni, 0.001 to 0.01% B, 0.05 to 0.3% N and ≤0.03% Al, further comprising small quantity of one or more kinds selected from Nb, Ti and V, and, if required, comprising one or more kinds selected from Mo, W and Cu and is obtained by laser welding in one pass using no filler. In the shape of a weld metal, provided that the width of the surface is defined as W<SB>0</SB>and the width at a depth of 1/2 is defined as W<SB>1/2</SB>, W<SB>0</SB>/W<SB>1/2</SB>≥0.6 is satisfied. Further, provided that the output of a laser is defined as P(kW), the focal position of the laser is defined as f(mm), and the thickness of the base material is defined as t(mm), welding velocity v(cm/min) is controlled to the range within the formula. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a welded joint of austenitic alloy steel having excellent strength, creep strength and corrosion resistance, and a method for producing the same, which are used in high-temperature devices such as power generation boilers.

  Austenitic alloy steels with high Cr and high Ni are used for high-temperature equipment such as boilers for power generation. However, various alloy steels have been developed by considering the application under severer conditions due to recent efficiency improvements and changes in the usage environment. I came. When such a heat-resistant alloy steel material is used as a welded structure, the high-temperature strength and corrosion resistance of the welded portion are required to be comparable to the base material.

  Welded joints of these alloy steels are usually constructed by arc welding, but even if the same material as the base metal is used as is for the welding material, there are defects due to the fluidity of the molten metal during melting, and composition changes due to oxidation, etc. In addition, since it is in a solidified state after melting, the grain structure of the weld metal is coarse and segregation of the constituent elements occurs, and its strength and corrosion resistance are generally far inferior to those of the base material. Become.

  For this reason, a welding material having a composition close to that of the base material, excellent weldability, performance of the welded joint after construction, in particular, high temperature strength and creep strength equal to or higher than that of the base material, and the use thereof are used. Various welded joints have been proposed. For example, Patent Document 1 discloses an invention of a welding material in which Nb and Mo are added to a composition close to a base material of high Cr and high Ni, and further, the N is increased during welding to cause a decrease in strength. . Also, Patent Documents 2, 3 and 4 etc. also describe a welding material in which other component elements such as Nb and Mo are added based on steel having a composition close to that of the base material and the content range of specific elements is regulated. An invention has been proposed in which the strength and creep strength of a weld metal or weld joint is improved.

  However, these inventions are all based on the multi-layer welding method in which a welding material is used separately from the base material by TIG or MIG, and many passes are required to obtain a welded joint, and the efficiency of the welding operation is high. Absent.

  In recent years, high energy beam welding, such as electron beams and lasers, has rapidly become widespread. Since the electron beam and laser beam can be easily converged, the energy density at the time of heat input is about 1000 times that of an arc or the like, and welding having a melted portion having a deep penetration depth compared to the width is realized. it can. For this reason, the heat affected zone can be reduced, and precise welding with less welding deformation and distortion is possible. Electron beam welding needs to be performed in a vacuum and X-rays are generated, so that a vacuum chamber and protective equipment are required. However, laser beam welding can be performed in the atmosphere and does not generate X-rays. From such a point, it has been put to practical use in welding that requires joining of thin plates and fine parts.

  In the case of high-temperature austenitic alloy steel materials, medium-thickness materials with a thickness of about 4 to 25 mm are targeted, but multi-layer welding with TIG or the like is usually performed. On the other hand, in order to apply laser beam welding, the joint forming portion of the base material is abutted, and the beam is irradiated and melt-bonded along the abutting surface.

  By adopting such a laser welding method, (1) high-efficiency and high-speed welding in one pass is possible, (2) the heat-affected zone can be narrowed, and (3) the same weld metal as the base metal The advantage that it can be formed is considered. However, the laser welding method has not yet been put to practical use as a welded joint for a high temperature austenitic alloy steel. The high temperature characteristics of the obtained welded joints are that there is no problem with corrosion resistance if the chemical composition of the weld metal is almost the same as that of the base metal, but regarding the soundness and strength of the weld, especially the creep strength at high temperatures. This is probably because it is not clear enough.

JP-A-6-142980 JP-A-8-71784 JP 11-277292 A JP 2004-58062 A

  The laser welding method has the advantage that the heat-affected zone of the joint is small and high-speed welding is possible, but it is not applied to austenitic alloy steel materials used at high temperatures. This is presumably because the high temperature strength of the welded joint is not always sufficient. An object of the present invention is to provide a laser-welded joint of austenitic alloy steel having the same strength and creep strength as the base metal and a method for producing the same.

The gist of the present invention is as follows.
(A) A welded joint of austenitic alloy steel used for heat resistance, which is a joint by laser welding of one pass without using a filler, and the shape of the weld metal has a bead width of the laser irradiation side surface of W ₀ , An austenitic alloy steel laser weld joint characterized in that the following equation (1) is satisfied when the width at a half depth position from the surface of the weld metal is W _1/2 .

W ₀ / W _1/2 ≧ 0.6 (1)
(B) In mass%, C: 0.2% or less, Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, Cr: 15 to 35%, Ni: 6-45%, B: 0.001-0.01%, N: 0.05-0.3%, Al: 0.03% or less, Nb: 0.01-1.5%, Ti : A welded joint containing one or more of 0.005 to 0.5% and V: 0.01 to 1%, with the balance being Fe and an austenitic alloy steel that is an impurity, and a filler In this case, the weld metal shape has a bead width W ₀ on the laser irradiation side surface and a width at a half depth position from the surface of the weld metal W _1/2 . A laser welded joint of austenitic alloy steel characterized by satisfying the following formula (1).
W ₀ / W _1/2 ≧ 0.6 (1)

(C) In mass%, C: 0.2% or less, Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, Cr: 15 to 35%, Ni: 6-45%, B: 0.001-0.01%, N: 0.05-0.3%, Al: 0.03% or less, Nb: 0.01-1.5%, Ti : 0.005 to 0.5% and V: 0.01 to 1% or more, Mo: 0.2 to 3%, W: 0.2 to 4%, and Cu: 0. 2 to 5% of 1 type or 2 types or more and the balance is a weld joint using Fe and impurities as austenitic alloy steel as a base material, and a joint by laser welding of one pass without using a filler, when the shape of the weld metal bead width of the laser irradiation surface W _0, the width at half depth position from the surface of the weld metal and W _1/2, the following ( ) Laser welded joint of austenitic steel alloy which is characterized in that, thereby satisfying the expression.
W ₀ / W _1/2 ≧ 0.6 (1)

・・・・・ （２） (D) With respect to the steel material having the thickness t (mm) of the austenitic alloy steel described in (a), (b) or (c) above, the output of laser welding is P (kW), and the focal position of laser irradiation is When f (mm) (however, the steel surface position is 0, the upper side from the surface is +, and the inner side is-), the welding speed v (cm / min) is defined as a range defined by the following equation (2). The method for producing a laser-welded joint of austenitic alloy steel according to (a), (b) or (c) above, wherein one-pass laser welding is performed without using a filler.

(2)

  The welded joint of the present invention has the same strength and creep strength as the base metal, and the laser welding method can be effectively applied to a welded structure of austenitic alloy steel material used at high temperatures. Is possible.

  The present inventors performed laser welding under various conditions on a welded joint that was laser-welded in one pass without using a filler to an austenitic alloy steel material used at high temperatures, preventing welding defects, ensuring strength, and Various conditions for obtaining joints with excellent creep strength were investigated. The reason why the one-pass through welding using no filler is considered to be advantageous for suppressing thermal deformation, preventing weld solidification cracking, and ensuring corrosion resistance, weld metal strength and creep strength.

  The welding method is keyhole type deep penetration welding in which cross sections to be welded are held together and irradiated with a laser beam along the abutting surface. Using austenitic alloy steel materials with different chemical compositions and plate thicknesses, and welding conditions such as welding speed and heat input were changed, and the resulting welded joints were subject to weld defects, weld metal shape, strength, and creep. The strength was investigated.

  First, when examining the shape of the weld metal in a cross section perpendicular to the welding direction, if the welding speed is high and the heat input is small, melting that penetrates the entire thickness of the butt portion cannot be obtained, and partial melting occurs. It becomes a so-called pear-shaped shape in which the penetration width on the surface side irradiated with the beam is narrower than the penetration width inside. When it becomes such a shape, there exists a tendency for the solidification crack of a weld metal to generate | occur | produce easily.

  On the other hand, if the welding speed is low and the heat input is large, the weld metal melts down in severe cases, resulting in poor welding. It becomes a so-called bottle-shaped shape that widens widely. In such a welded joint, the strength is low, and the creep strength is also lower than that of the base material. This is presumably because the cooling rate after melting slows down and the crystal structure becomes coarse, or the evaporation of nitrogen in the alloy progresses.

Thus, when the relationship between the shape of the weld metal, the strength of the joint at normal temperature and the creep strength at high temperature is examined, the following has been clarified. That is, if the shape of the weld metal in a cross section perpendicular to the welding direction is represented as shown in FIG. 1, the bead width of the upper laser irradiation side surface is W ₀ , and 1 / of the penetration depth L from the surface of the weld metal. 2 When the width at the depth position is W _1/2 and satisfies the following formula (1), there is no welding defect such as solidification cracking, and the room temperature strength and high temperature creep strength are the same as the base metal. It becomes a welded joint.
W ₀ / W _1/2 ≧ 0.6 (1)

  If the heat input is too small with respect to the welding speed, not only deep penetration through the thickness cannot be obtained, but the shape of the weld metal becomes a pear-shaped shape as described above, and the equation (1) is not satisfied. Conversely, if the heat input is too much for the welding speed, the width at the center of the thickness becomes large and the equation (1) is not satisfied, but in that case the strength and creep strength are greatly inferior to the base material.

Therefore, if the shape of the weld metal of the joint satisfies the formula (1), the laser welded joint of austenitic alloy steel having the same strength and creep strength as the base metal is obtained. In addition, if such a weld metal shape is used, the occurrence of weld defects such as solidification cracks is suppressed. Here, when the depth from the surface of the weld metal penetrates through the thickness, the position of W _1/2 becomes a position of 1/2 of the thickness.

Note that the lower limit value 0.6 of W ₀ / W _1/2 is defined in the expression (1), and the upper limit value is not particularly restricted, but it can be realized in one-pass laser welding without using an actual filler. 3 is the limit.

・・・・・ （２）
ここで、Ｐはレーザ出力（ｋＷ）、ｆはレーザの焦点位置（ｍｍ）（ただし被溶接材の表面を０とし、上側を＋、内部側を−とする）、ｔは母材厚さ（ｍｍ）、ｖは溶接速度（ｃｍ／ｍｉｎ）である。なお、上記式はＰ：１〜５０ｋＷ、ｆ：−２〜＋６ｍｍ、ｔ：４〜２５ｍｍ程度の範囲で適用できる。 Based on the above results, the welding conditions for obtaining the weld metal having such a shape were further examined. The welding method is laser beam penetration welding in one pass. Using austenitic alloy steel plates with different thicknesses, welding is performed by changing the welding speed, laser output, and the focal point of the beam. As a result of measuring the shape of the metal and organizing the conditions when a weld metal having a shape satisfying the expression (1) was realized, the following expression (2) could be obtained.

(2)
Here, P is the laser output (kW), f is the focal position of the laser (mm) (where the surface of the welded material is 0, the upper side is +, the inner side is-), and t is the base material thickness ( mm) and v are welding speeds (cm / min). The above formula can be applied in the range of P: 1 to 50 kW, f: -2 to +6 mm, and t: 4 to 25 mm.

  When welding is performed at a speed lower than the welding speed range determined by the above formula (2), not only the weld metal having the shape shown by the formula (1) can be obtained, but the weld metal does not penetrate in the thickness direction and solidifies. Cracks are likely to occur. If welding is performed at a speed exceeding the welding speed range of the above formula (2), the weld metal having the shape shown by the formula (1) cannot be obtained, resulting in inferior strength and insufficient creep strength.

The laser heat source used in the present invention is not particularly limited, but a YAG laser, a CO ₂ laser, or the like may be used.
Next, the austenitic alloy steel (base material steel) used for the welded joint of the present invention will be described. Hereinafter, the content of each element is mass%.

C: 0.2% or less C is an element effective for ensuring the strength and creep strength required for an austenitic alloy. In order to obtain the effect, the content is preferably 0.01% or more. However, if the content exceeds 0.2%, undissolved carbides remain in the solution treatment state, which not only contributes to the improvement of high-temperature strength, but also adversely affects mechanical properties such as toughness. Therefore, the content is made 0.2% or less. In addition, from a viewpoint of a hot workability fall or toughness degradation, it is good to set it as 0.12% or less desirably.

Si: 2% or less Si is used as a deoxidizer and is an element effective for improving the action of N added as a solid solution strengthening element, and is preferably contained in an amount of 0.1% or more. On the other hand, if the content increases, weldability and hot workability deteriorate, so the content is made 2% or less. Moreover, since N addition steel like this invention steel has the effect | action which reduces the solid solubility of N, it is desirable to set it as 0.8% or less.

Mn: 3% or less It is effective as a deoxidizing agent in the same manner as Si, has an action of suppressing hot workability deterioration due to the inclusion of S, and has a solid solubility of N added as a solid solution strengthening element. It is an effective element for the rise. However, excessive content causes embrittlement, so it is 3% or less. From the viewpoint of creep rupture strength and the like, it is not necessary to set a lower limit to the content, but it is preferable to contain 0.1% or more from the viewpoint of the above-described deoxidation effect and improvement of hot workability.

P: 0.03% or less Since it is an element that is mixed as an impurity and increases the weld solidification cracking susceptibility during welding, the smaller the better. However, since extreme reduction leads to deterioration of economic efficiency, the limit is set to 0.03% or less as a limit that does not have a significant adverse effect.

S: 0.01% or less As with P, it is an element that increases the susceptibility to weld solidification cracking during welding, and segregates at the grain boundary to lower the grain boundary fixing force, causing reheat cracking. Less is better. The limit of 0.01% or less is set as a limit at which no significant adverse effect appears.

Cr: 15-35%
Cr is an element necessary for securing strength at high temperatures, oxidation resistance, and corrosion resistance, and it is necessary to ensure a content of 15% or more in order to exert its sufficient effect. However, if it is excessively contained, the stability of the austenite structure decreases at high temperatures and the strength decreases, so the upper limit is made 35%.

Ni: 6 to 45%
Ni is an element necessary for stabilizing the austenite structure and improving the creep strength, and it is necessary to contain 6% or more. Furthermore, in order to ensure the stability of the structure at a high temperature and for a long time, the content is preferably 15% or more. However, the effect is saturated when a large amount is added, and the addition of more than that causes only an increase in cost, so it is limited to 45%. Preferably it is 35% or less, More preferably, it is 25% or less.

B: 0.001 to 0.01%
B is contained in a small amount because B is an element that improves the creep strength by strengthening dispersion precipitation of fine nitrides and strengthening grain boundaries. If the content is less than 0.001%, a sufficient effect cannot be obtained. On the other hand, if excessively added, the sensitivity to weld solidification cracking is remarkably increased, so 0.01% or less.

N: 0.05-0.3%
N has an effect of solid solution strengthening, and further forms NbN, NbCrN, TiN, VN and the like, and is an extremely effective element for improving strength and creep strength by precipitation strengthening thereof. In particular, in the non-filler laser welding in one pass of the present invention, the alloy component from the welding wire or the like is not replenished as in arc welding, so the N content of the weld metal is reduced due to evaporation dissipation during welding. In consideration, it is necessary to contain 0.05% or more. Further, since N has a solid solubility limit larger than that of C, even if it is contained in a relatively large amount, it can be dissolved in a solution state, and the toughness reduction accompanying nitride precipitation that occurs during aging is also relatively small. However, if the content is too large, the toughness is greatly deteriorated due to aging, and it causes welding defects such as blow holes, so the content is made 0.3% or less.

Al: 0.03% or less Al is used as a deoxidizer at the time of melting, and as a result, remains in the steel, but if it remains excessively, it forms inclusions in the weld metal and creep ductility In order to cause a decrease, the Al content is set to 0.03% or less. In addition, when it can fully deoxidize with other elements, such as Mn and Si, it is not necessary to add, In that case, it becomes an impurity level.

One or more of Nb: 0.01 to 1.5%, Ti: 0.005 to 0.5% and V: 0.01 to 1% These elements form carbonitrides, It has the effect of improving the strength and creep strength by fine precipitation and refinement of the structure and precipitation strengthening. Therefore, in order to make it contain and to exhibit the effect, it is necessary to contain 0.01% or more for Nb, 0.005% or more for Ti, and 0.01% or more for V. On the other hand, if excessively contained, the sensitivity to weld solidification cracking is increased, and weldability and workability are deteriorated. Therefore, Nb is 1.5% or less, Ti is 0.5% or less, and V is 1% or less. Must be limited to. In the case of Nb, NbN, NbCrN and NbC are formed at the same time and are finely deposited in the grains and grain boundaries of the solidified structure, and the effect of improving the strength and creep strength of the weld metal is great. When it contains, it is preferable to make it contain 0.1% or more.

One or more of Mo: 0.2-3%, W: 0.2-4% and Cu: 0.2-5% Mo, W, and Cu all have the effect of improving creep strength However, if necessary, one or more of these may be contained. The reason why the creep strength is improved is considered that Mo and W are due to the strengthening of the matrix by solid solution, and Cu is precipitated at a high temperature to strengthen the matrix. In order to exhibit such an effect, Mo, W, and Cu are contained by 0.2% or more, respectively. However, if the content is too large, not only is the effect saturated and wasted, but workability is deteriorated and susceptibility to solidification cracking at the time of welding increases, so Mo appears up to 3%. It is preferable that W is up to 4% and Cu is up to 5%.

  After austenitic alloy steel having the chemical composition shown in Table 1 was melted using a high-frequency heating vacuum melting furnace, the obtained ingot was subjected to heat treatment such as forging, rolling, solution treatment, etc. by a normal method, A plate-shaped test piece having a thickness of 6 to 10 mm, a width of 100 mm, and a length of 100 mm was prepared by cutting.

これらの試験片にて、同じ組成同じ板厚の母材の端面を突合わせ、突合わせ部にレーザビームを照射して１パスのレーザ溶接をおこなった。溶接熱源にＬＤ励起ＹＡＧレーザ溶接機を使用し、母材および板厚と、レーザ出力、焦点位置および溶接速度等の溶接条件とを変えて、溶接継手を作製した。表２に作製した継手の使用母材、溶接条件を示す。溶接条件の焦点位置は、板面を０とし、板面より上を＋、板面以下を−として示している。また、板厚、レーザ出力および焦点位置から定まる（２）式による溶接速度範囲についても、合わせて表２に示す。

With these test pieces, the end surfaces of the base materials having the same composition and the same thickness were butted together, and a laser beam was irradiated to the butted portion to perform one-pass laser welding. An LD-excited YAG laser welder was used as the welding heat source, and welding joints were produced by changing the base material and plate thickness, and welding conditions such as laser output, focal position and welding speed. Table 2 shows the base metal used and the welding conditions of the manufactured joint. The focal position of the welding conditions is indicated by 0 on the plate surface, + above the plate surface, and-below the plate surface. Table 2 also shows the welding speed range according to equation (2) determined from the plate thickness, laser output, and focal position.

  About the obtained joint test piece, the penetration shape and the solidification crack in a cross section, the measurement of hardness, and the creep test were done. The cross-sectional investigation is conducted at the central part (1/2) in the longitudinal direction of the weld and at 1/4 and 3/4 positions, and the hardness is 1 mm along the center of the plate thickness in the joint cross section as shown in FIG. The Vickers hardness with a test force of 9.807 N was measured at 14 points. In the creep test, the test piece having the shape shown in FIG. 3 is cut out so that the weld is in the center, and the fracture time in the base material is about 1000 hours, that is, 700 ° C. and 147. The break times were investigated under the conditions of 1 MPa, A4 and A5 materials at 700 ° C. and 156.9 MPa.

  The test results are shown in Table 2. With respect to the penetration shape, those having a penetration penetration shape are indicated as “good”, those having no penetration penetration shape and those having a penetration penetration shape are indicated as “bad”.

With regard to cracking, “no” was given when no solidification cracking was found in the weld metal, and “yes” when cracking occurred. Further, W ₀ / W _1/2 defined by the equation (1) was determined from the cross-sectional shape of the weld metal, and the value was shown. For joint hardness, the hardness distribution measurement result from the base metal to the weld metal indicates that the weld metal hardness is 90% or more of the base metal hardness. The mark was described. In such a measurement, when the hardness of the weld metal shows a value of 90% or more of the base metal hardness, the strength of the joint shows a value equal to or higher than that of the base material when a joint tensile test is performed.

  When the creep strength shows a rupture time of 80% or more, that is, 800 hours or more with respect to the rupture time of the base material, it is judged that the creep strength is good. Note that the creep strength was not measured when the penetration shape was poor or when cracks occurred.

As is apparent from the results in Table 2, when welding is performed within the range where the welding speed is regulated by the formula (2), the penetration shape defect that the penetration is not penetrated or the burnout occurs is There has been obtained a joint which does not occur, has no solidification cracking, and has a value of W ₀ / W _1/2 of 0.6 or more.

In the laser welded joint of the present invention in which the value of W ₀ / W _1/2 is 0.6 or more, that is, the shape of the weld metal satisfies the formula (1), the hardness or the strength estimated from the hardness And the creep strength is equivalent to that of the base material.

It is a schematic diagram of a weld metal shape showing the measurement positions of W ₀ and W _1/2 . It is a figure which shows the measurement position of the hardness of the weld metal of a coupling. It is a figure explaining the test piece which measures the creep strength of a coupling.

Claims (4)

This is a welded joint made of austenitic alloy steel used for heat resistance as a base material, and is a joint by laser welding of one pass without using a filler, and the shape of the weld metal has a bead width W ₀ on the laser irradiation side surface. A laser welded austenitic alloy steel characterized by satisfying the following formula (1) when the width at the 1/2 depth position from the surface of the weld metal is W _1/2 .
W ₀ / W _1/2 ≧ 0.6 (1) In mass%, C: 0.2% or less, Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, Cr: 15 to 35%, Ni: 6 -45%, B: 0.001-0.01%, N: 0.05-0.3%, Al: 0.03% or less, Nb: 0.01-1.5%, Ti: 0.00. One or more of 005 to 0.5% and V: 0.01 to 1%, with the balance being a welded joint made of austenitic alloy steel, which is Fe and impurities, with no filler This is a joint by laser welding of one pass, and when the shape of the weld metal is W ₀ on the laser irradiation side surface and the width at the 1/2 depth position from the surface of the weld metal is W _1/2 A laser weld joint of austenitic alloy steel characterized by satisfying the formula (1).
W ₀ / W _1/2 ≧ 0.6 (1) In mass%, C: 0.2% or less, Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, Cr: 15 to 35%, Ni: 6 -45%, B: 0.001-0.01%, N: 0.05-0.3%, Al: 0.03% or less, Nb: 0.01-1.5%, Ti: 0.00. One or more of 005 to 0.5% and V: 0.01 to 1%, Mo: 0.2 to 3%, W: 0.2 to 4%, and Cu: 0.2 to 5 %, And the balance is a welded joint made of austenitic alloy steel, which is Fe and impurities, and is a joint by laser welding of one pass without using a filler. W ₀ to bead width shape the laser irradiation surface, the width at half depth position from the surface of the weld metal when a W _1/2, the following equation (1) Laser welded joint of austenitic steel alloy, characterized in that it is intended to satisfy.
W ₀ / W _1/2 ≧ 0.6 (1) 4. For the steel material of thickness t (mm) of the austenitic alloy steel according to claim 1, 2 or 3, the laser welding output is P (kW) and the focal point of laser irradiation is f (mm) (however, the steel material When the surface position is 0, the upper side from the surface is +, and the inner side is-), the welding speed v (cm / min) is set to a range defined by the following equation (2), and a one-pass laser that does not use a filler The method for manufacturing a laser welded joint of austenitic alloy steel according to claim 1, 2 or 3, wherein welding is performed.

(2)

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