WO2024095678A1 - Solid wire and gas-shielded arc welding method - Google Patents

Solid wire and gas-shielded arc welding method Download PDF

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Publication number
WO2024095678A1
WO2024095678A1 PCT/JP2023/036286 JP2023036286W WO2024095678A1 WO 2024095678 A1 WO2024095678 A1 WO 2024095678A1 JP 2023036286 W JP2023036286 W JP 2023036286W WO 2024095678 A1 WO2024095678 A1 WO 2024095678A1
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mass
less
wire
content
weld metal
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PCT/JP2023/036286
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French (fr)
Japanese (ja)
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晋也 磯野
英亮 高内
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株式会社神戸製鋼所
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Publication of WO2024095678A1 publication Critical patent/WO2024095678A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/23—Arc welding or cutting taking account of the properties of the materials to be welded
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium

Definitions

  • the present invention relates to a solid wire and a gas-shielded arc welding method.
  • 9Cr-1Mo-Nb-V steel steel made by adding Nb, V, etc. to 9Cr-1Mo steel, which contains 8% to 10% by mass of Cr and 0.85% to 1.20% by mass of Mo, is called 9Cr-1Mo-Nb-V steel.
  • Cr-Mo ferritic high-strength heat-resistant steels such as 9Cr-1Mo-Nb-V steel have excellent high-temperature properties and are used in boilers and pressure vessels for thermal and nuclear power plants.
  • Patent Document 1 discloses a welding material that can produce welds with excellent back-sealing and mechanical properties without using back shielding gas.
  • the welding material described in Patent Document 1 has specified contents of C, Cr, Mo, Ni, and Al, and the relationship between the Cr and Mn contents and the Si content, the relationship between the S content and the Mn content, and the total amount of the Al content and the O content are controlled, and the contents of P and S in the impurities are specified.
  • the weld metal of ferritic high-strength heat-resistant steel such as 9Cr-1Mo-Nb-V steel may be subjected to post-weld heat treatment (PWHT) for the purpose of improving toughness, etc.
  • PWHT post-weld heat treatment
  • the high-temperature transformation temperature (Ac1 transformation point) has not been considered in the welding material described in the above Patent Document 1, and depending on the PWHT temperature, it may not be possible to ensure the toughness of the weld metal.
  • Patent Document 1 does not fully consider the suppression of the formation of ⁇ -ferrite, and in order to form weld metal that is adequate for use in boilers and pressure vessels for thermal and nuclear power plants, it is important to further suppress the formation of ⁇ -ferrite.
  • the present invention was made in consideration of the above-mentioned problems, and aims to provide a solid wire and a gas-shielded arc welding method that can be used to weld steel containing 1% to 10% by mass of Cr, and that can produce a back wave with excellent appearance without using back shielding gas, and can also produce a weld metal with excellent mechanical properties.
  • a solid wire used for welding steel materials containing 1 mass% or more and 10 mass% or less of Cr For the total mass of wire, C: 0.05% by mass or more and 0.15% by mass or less, Si: 0.8% by mass or more and 1.7% by mass or less, Mn: 0.4% by mass or more and 1.2% by mass or less, Cr: 7.5% by mass or more and 13.0% by mass or less, Mo: 0.70% by mass or more and 1.5% by mass or less, Nb: 0.010% by mass or more and 0.10% by mass or less, V: 0.10% by mass or more and 0.50% by mass or less, N: 0.010% by mass or more and 0.070% by mass or less; P: 0.030% by mass or less, S: 0.030% by mass or less, Ni: 0.80 mass% or less, Ti: 0.025% by mass or less, Al: 0.020% by mass or less, Co: 0.70% by mass or less; The balance of the solid wire is Fe and unavoidable impurities.
  • the solid wire according to (1) comprising:
  • the above object of the present invention is achieved by the following configuration (4) of the gas shielded arc welding method.
  • the present invention provides a solid wire that can produce a back wave with excellent appearance without using back shielding gas, and can also produce a weld metal with excellent mechanical properties, as well as a gas-shielded arc welding method that uses this solid wire.
  • solid wire may be simply referred to as "wire.”
  • present invention is not limited to the embodiments described below, and can be modified as desired without departing from the gist of the present invention.
  • the solid wire according to the present embodiment is used for welding steel materials containing 1% by mass or more and 10% by mass or less of Cr.
  • a combination of 9% Cr steel and 2% Cr steel can be used to form a welded steel material, and the solid wire according to the present embodiment can also be applied to dissimilar material joints.
  • the solid wire according to the present embodiment is particularly preferably used for welding 9Cr-1Mo-Nb-V steel.
  • a Cr content of 8% by mass or more and 10% by mass or less may be referred to as 9% Cr steel.
  • the shape of the steel material used as the steel material to be welded is not particularly limited, and it can be used, for example, to weld steel plates, steel pipes, etc.
  • C is an important element that combines with Cr, Mo, V, and Nb to form carbides and ensure the strength of the weld metal. Furthermore, as an austenite-forming element, C contributes to suppressing the formation of ⁇ -ferrite in the weld metal. If the C content relative to the total mass of the wire is less than 0.05 mass%, the desired strength of the weld metal cannot be obtained. Therefore, the C content relative to the total mass of the wire is set to 0.05 mass% or more, preferably 0.06 mass% or more, and more preferably 0.07 mass% or more.
  • the C content relative to the total mass of the wire is set to 0.15% by mass or less, preferably 0.14% by mass or less, and more preferably 0.13% by mass or less.
  • Si has the effect of preferentially forming an oxide film on the uranami surface that has a low melting point and is unlikely to inhibit the solidification of the weld metal, and preventing poor uranami formation due to the oxidation of Cr during welding. If the Si content relative to the total mass of the wire is less than 0.8 mass%, the above effect cannot be sufficiently obtained and the uranami shape deteriorates. Therefore, the Si content relative to the total mass of the wire is set to 0.8 mass% or more, preferably 0.9 mass% or more, and more preferably 1.0 mass% or more.
  • the Si content relative to the total mass of the wire is set to 1.7 mass% or less, preferably 1.6 mass% or less, and more preferably 1.5 mass% or less.
  • Mn functions as a deoxidizer for the weld metal, and is an element that has the effect of improving the strength and toughness of the weld metal. Mn is also an austenite-forming element, and contributes to suppressing the formation of ⁇ -ferrite in the weld metal. If the Mn content relative to the total mass of the wire is less than 0.4 mass%, it causes insufficient deoxidation and is unable to fully suppress the residual ⁇ -ferrite in the weld metal, resulting in a decrease in the toughness of the weld metal.
  • the Mn content relative to the total mass of the wire is set to 0.4 mass% or more, preferably 0.5 mass% or more, and more preferably 0.6 mass% or more.
  • the Mn content exceeds 1.2 mass% relative to the total mass of the wire, the high-temperature strength of the weld metal deteriorates.
  • the solidification temperature of the segregation part decreases, and the transformation point decreases, making PWHT at high temperatures difficult.
  • Mn generates a complex oxide together with Cr, causing poor formation of the uranami. Therefore, the Mn content relative to the total mass of the wire is set to 1.2 mass% or less, preferably 1.1 mass% or less, and more preferably 1.0 mass% or less.
  • Cr 7.5 mass% or more and 13.0 mass% or less>
  • Cr is a main element of high Cr content welded steel material in which good uranami formation is difficult in welding using the solid wire according to this embodiment, and is an essential element for ensuring oxidation resistance at high temperatures and high-temperature strength of the weld metal. If the Cr content relative to the total mass of the wire is less than 7.5 mass%, the oxidation resistance and high-temperature strength of the weld metal become insufficient. Therefore, the Cr content relative to the total mass of the wire is set to 7.5 mass% or more, preferably 7.8 mass% or more, and more preferably 8.0 mass% or more.
  • the Cr content exceeds 13.0% by mass relative to the total mass of the wire, even if the Si content is controlled as described above, an oxide film that inhibits uniform solidification of the high melting point weld metal is formed on the back surface.
  • the Cr content relative to the total mass of the wire is set to 13.0% by mass or less, preferably 12.5% by mass or less, and more preferably 12.0% by mass or less.
  • Mo 0.70 mass% or more and 1.5 mass% or less> Mo is a solid solution strengthening element and also has the effect of increasing high-temperature strength by precipitation of carbides. If the Mo content relative to the total mass of the wire is less than 0.70 mass%, the high-temperature strength of the weld metal becomes insufficient. Therefore, the Mo content relative to the total mass of the wire is set to 0.70 mass% or more, preferably 0.75 mass% or more, and more preferably 0.80 mass% or more. On the other hand, if the Mo content exceeds 1.5 mass% relative to the total mass of the wire, it causes residual ⁇ -ferrite, which deteriorates the toughness and creep performance of the weld metal. Therefore, the Mo content relative to the total mass of the wire is set to 1.5 mass% or less, preferably 1.3 mass% or less, and more preferably 1.2 mass% or less.
  • Nb is an element that has the effect of improving the strength of the weld metal by solid solution strengthening and precipitating as nitrides. If the Nb content relative to the total mass of the wire is less than 0.010 mass%, the effect of improving the strength of the weld metal cannot be sufficiently obtained. Therefore, the Nb content relative to the total mass of the wire is set to 0.010 mass% or more, preferably 0.013 mass% or more, and more preferably 0.015 mass% or more. On the other hand, if the Nb content exceeds 0.10 mass% relative to the total mass of the wire, residual ⁇ ferrite is caused, and the toughness of the weld metal is significantly deteriorated. Therefore, the Nb content relative to the total mass of the wire is set to 0.10 mass% or less, preferably 0.09 mass% or less, and more preferably 0.08 mass% or less.
  • V is an element that precipitates in the weld metal as a carbonitride and has the effect of improving the strength of the weld metal. If the V content relative to the total mass of the wire is less than 0.10 mass%, the effect of improving the strength of the weld metal cannot be sufficiently obtained. Therefore, the V content relative to the total mass of the wire is set to 0.10 mass% or more, preferably 0.13 mass% or more, and more preferably 0.15 mass% or more. On the other hand, if the V content exceeds 0.50 mass% relative to the total mass of the wire, residual ⁇ ferrite is caused and the toughness of the weld metal is deteriorated. Therefore, the V content relative to the total mass of the wire is set to 0.50 mass% or less, preferably 0.40 mass% or less, and more preferably 0.30 mass% or less.
  • N is an element that contributes to solid solution strengthening and stabilization of strength by precipitating as nitrides. It is also an austenite forming element and has the effect of suppressing ⁇ -ferrite in the weld metal. If the N content relative to the total mass of the wire is less than 0.010 mass%, the above effect cannot be sufficiently obtained, the strength is reduced, and ⁇ -ferrite is generated. Therefore, the N content relative to the total mass of the wire is set to 0.010 mass% or more, preferably 0.015 mass% or more, and more preferably 0.020 mass% or more.
  • the N content with respect to the total mass of the wire exceeds 0.070 mass%, blowholes occur. Therefore, the N content with respect to the total mass of the wire is set to 0.070 mass% or less, preferably 0.065 mass% or less, and more preferably 0.060 mass% or less.
  • P is an impurity element and a component that increases hot cracking susceptibility. If the P content with respect to the total mass of the wire exceeds 0.030 mass%, there is a concern that hot cracking may occur. Therefore, the P content with respect to the total mass of the wire is set to 0.030 mass% or less, preferably 0.020 mass% or less, and more preferably 0.015 mass% or less.
  • S has the effect of affecting convection in the molten pool, increasing the penetration depth, improving the stability of the arc, and forming a good backside wave.
  • the lower limit of the S content is not particularly limited and may be 0 mass %, but when S is contained in the wire for the purpose of further improving the backside wave formation ability, the S content relative to the total mass of the wire is preferably 0.003 mass % or more, and more preferably 0.005 mass % or more.
  • the S content relative to the total mass of the wire is set to 0.030% by mass or less, preferably 0.025% by mass or less, and more preferably 0.020% by mass or less.
  • Ni is an austenite-forming element and contributes to suppressing the formation of ⁇ -ferrite in the weld metal.
  • the lower limit of the Ni content is not particularly limited and may be 0 mass%, but when Ni is contained in the wire for the purpose of suppressing the formation of ⁇ -ferrite in the weld metal, the Ni content relative to the total mass of the wire is preferably 0.05 mass% or more, and more preferably 0.10 mass% or more.
  • the Ni content relative to the total mass of the wire is set to 0.80 mass% or less, preferably 0.60 mass% or less, and more preferably 0.50 mass% or less.
  • Ti forms an oxide film that inhibits uniform solidification of the weld metal, and deteriorates the formation of a good back bead shape. If the Ti content exceeds 0.025 mass% relative to the total mass of the wire, the back bead shape deteriorates. Therefore, the Ti content relative to the total mass of the wire is set to 0.025 mass% or less, preferably 0.018 mass% or less, and more preferably 0.015 mass% or less.
  • Al 0.020 mass% or less>
  • Al is an element that preferentially forms an oxide film on the uranami surface that has a low melting point and does not inhibit the solidification of the weld metal, but has a high slag generating ability, so there is a concern that slag inclusion may occur.
  • Al is a ferrite generating element, and excessive ⁇ ferrite is generated in the weld metal, which reduces the toughness of the weld metal.
  • Al preferentially forms nitrides over Nb and V, and therefore inhibits the generation of Nb and V nitrides that have the effect of ensuring high-temperature strength, resulting in a decrease in high-temperature strength. Therefore, the Al content of the wire is set to 0.020 mass% or less, preferably 0.015 mass% or less, and more preferably 0.012 mass% or less.
  • Co is an austenite-forming element like Ni and Mn, and contributes to suppressing the formation of ⁇ -ferrite in the weld metal, and the desired mechanical performance of the weld metal can be obtained by including Co in the wire.
  • the lower limit of the Co content is not particularly limited and may be 0 mass%, but when Co is included in the wire for the purpose of suppressing the formation of ⁇ -ferrite in the weld metal, the Co content relative to the total mass of the wire is preferably 0.005 mass%, more preferably 0.05 mass% or more, even more preferably 0.10 mass% or more, and particularly preferably 0.15 mass% or more.
  • the Co content relative to the total mass of the wire is set to 0.70% by mass or less, preferably 0.60% by mass or less, and more preferably 0.50% by mass or less.
  • the solid wire according to this embodiment may contain either Zr or Cu or both within the ranges shown below.
  • the contents of other components that the wire may further contain and the reasons for limiting them are explained below.
  • ⁇ Zr: 0.10 mass% or less> Zr, together with Si, is an element that preferentially forms an oxide film on the uranami surface that does not easily inhibit the solidification of the weld metal, so it is preferable to include Zr in the solid wire according to the present embodiment as necessary. If Zr is included in the wire in the range of 0.10 mass% or less, poor uranami formation due to oxidation of Cr during welding can be prevented without reducing toughness due to excessive generation of ⁇ ferrite. Therefore, when Zr is included in the solid wire according to the present embodiment, the Zr content relative to the total mass of the wire is 0.10 mass% or less, preferably 0.08 mass% or less, and more preferably 0.07 mass% or less. On the other hand, when Zr is contained in the wire in order to obtain the above-mentioned effect, the Zr content relative to the total mass of the wire is preferably 0.005 mass % or more, and more preferably 0.010 mass % or more.
  • the Cu content relative to the total mass of the wire is preferably 0.50 mass% or less, more preferably 0.40 mass% or less, and even more preferably 0.30 mass% or less.
  • the Cu content relative to the total mass of the wire is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.10 mass% or more.
  • the wire of this embodiment may be Cu-plated, and the Cu content includes the copper plating.
  • the balance of the solid wire according to the present embodiment is Fe and inevitable impurities.
  • the inevitable impurities refer to elements that are not intentionally added to the wire, and examples of elements other than those mentioned above include B, Sn, As, Sb, etc.
  • the total content of impurities in the solid wire is preferably 0.10 mass% or less, and more preferably 0.05 mass% or less.
  • the gas-shielded arc welding method according to the present embodiment is a welding method for welding steel materials containing 1% by mass or more and 10% by mass or less of Cr using the above-mentioned solid wire without using back shield gas.
  • the Cr content of the steel materials to be welded is, for example, 8% by mass to 10% by mass
  • the back wave is easily oxidized, and the shape and appearance of the back wave deteriorate.
  • a back wave having excellent back wave performance and mechanical performance can be formed not only for steel materials with a high Cr content in which the back wave is particularly easily oxidized, but also for steel materials containing 1% by mass to 10% by mass or less of Cr, without using back shield gas.
  • the type of welding is not particularly limited, and in addition to TIG (Tungsten Inert Gas) welding, MAG (Metal Active Gas) welding and MIG (Metal Inert Gas) welding can be used.
  • TIG Transmission Inert Gas
  • MAG Metal Active Gas
  • MIG Metal Inert Gas
  • the shielding gas used on the front side during welding with the solid wire according to this embodiment is not particularly limited, but may be, for example, Ar gas, carbon dioxide gas, a mixed gas of Ar gas and carbon dioxide gas, or a mixed gas of Ar gas and oxygen gas.
  • the flow rate of the gas is also not particularly limited, but may be, for example, 15 to 50 L/min.
  • the welding position using the solid wire according to the present embodiment is not particularly limited, and welding can be performed in various welding positions.
  • the wire diameter (diameter) of the solid wire according to the present embodiment is not particularly limited, but it can be applied to a wire having a diameter specified in a welding material standard such as AWS or JIS.
  • Solid wire manufacturing Solid wires were prepared so that the wires contained various amounts of the components.
  • the amounts (mass%) of the chemical components per total mass of the wires are shown in Table 1 below.
  • the remainder of the wires, excluding the chemical components shown in Table 1 below, is Fe and unavoidable impurities.
  • an area ratio of ⁇ -ferrite of less than 5% was rated as "A” (excellent), an area ratio of 5% or more but less than 10% was rated as “B” (good), and an area ratio of 10% or more was rated as “C” (bad).
  • Tensile test A tensile test piece having a diameter of 6 mm and a gauge length of 24 mm was taken from the center of the plate thickness of the obtained weld metal parallel to the weld line direction, and the room temperature tensile strength (TS: Tensile Strength) of the weld metal was measured in accordance with the tensile test method for metallic materials described in JIS Z 2241:2011.
  • the evaluation criteria were as follows: a tensile test result of 720 MPa or more was rated as “A” (excellent), a tensile test result of 620 MPa or more but less than 720 MPa was rated as "B” (good), and a tensile test result of less than 620 MPa was rated as "C” (poor).
  • the evaluation criteria for toughness based on Charpy impact value were as follows: a Charpy impact value of 60 (J/ cm2 ) or more, calculated by dividing the absorbed energy measurement result in a Charpy impact test at 20°C by the original cross-sectional area of the notch, was rated as "A"(excellent); a value of 34 (J/ cm2 ) or more and less than 60 (J/ cm2 ) was rated as "B"(good); and a value less than 34 (J/ cm2 ) was rated as "C" (poor).
  • the solid wire according to this embodiment can be applied in the same way when the Cr content of the welded steel material is 1% by mass or more and less than 8% by mass.
  • the Cr content of the welded steel material is 1% by mass or more and 10% by mass or less
  • a good weld metal can be obtained without using a back shielding gas.
  • Comparative Examples B1 to B7 the Si content in the solid wire was less than the lower limit specified in the present invention, and in Comparative Examples B5 to B7, the Ti content in the solid wire exceeded the upper limit specified in the present invention. Therefore, the evaluation result of the back wave was poor.
  • Comparative Example B8 the Si content in the solid wire exceeded the upper limit specified in the present invention, so the area ratio of ⁇ ferrite increased.
  • Comparative Examples B9 and B10 the Si content in the solid wire exceeded the upper limit specified in the present invention, so the area ratio of ⁇ ferrite increased and the evaluation result of the toughness was poor.

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Abstract

Provided is a solid wire with which a penetration bead with an excellent appearance and a weld metal having excellent mechanical performance can be obtained without using any back shielding gas. The solid wire, which is for use in welding steel materials having Cr contents of 1-10 mass%, contains, in terms of mass% with respect to the whole wire, 0.05-0.15% C, 0.8-1.7% Si, 0.4-1.2% Mn, 7.5-13.0% Cr, 0.70-1.5% Mo, 0.010-0.10% Nb, 0.10-0.50% V, and 0.010-0.070% N and has a P content of 0.030% or less, an S content of 0.030% or less, an Ni content of 0.80% or less, a Ti content of 0.025% or less, an Al content of 0.020% or less, and a Co content of 0.70% or less, with the remainder comprising Fe and unavoidable impurities.

Description

ソリッドワイヤ及びガスシールドアーク溶接方法Solid wire and gas shielded arc welding method
　本発明は、ソリッドワイヤ及びガスシールドアーク溶接方法に関する。 The present invention relates to a solid wire and a gas-shielded arc welding method.
　一般的に、Ｃｒ：８質量％～１０質量％及びＭｏ：０．８５質量％～１．２０質量％等を含有する９Ｃｒ－１Ｍｏ鋼に、Ｎｂ、Ｖなどが添加された鋼材は、９Ｃｒ－１Ｍｏ－Ｎｂ－Ｖ鋼といわれている。このような９Ｃｒ－１Ｍｏ－Ｎｂ－Ｖ鋼に代表されるＣｒ－Ｍｏフェライト系高強度耐熱鋼は、高温特性に優れており、火力発電、原子力発電のボイラや圧力容器等に使用されている。 　Generally, steel made by adding Nb, V, etc. to 9Cr-1Mo steel, which contains 8% to 10% by mass of Cr and 0.85% to 1.20% by mass of Mo, is called 9Cr-1Mo-Nb-V steel. Cr-Mo ferritic high-strength heat-resistant steels such as 9Cr-1Mo-Nb-V steel have excellent high-temperature properties and are used in boilers and pressure vessels for thermal and nuclear power plants.
　上記のような高Ｃｒ含有量の鋼材を、突合せ片側溶接継手としてガスシールドアーク溶接する場合に、裏波表面の高融点Ｃｒ酸化物の形成による裏波溶接ビードの外観不良を防止するために、初層の溶接には不活性ガスによるバックシールドが必要とされている。しかし、鋼材の裏側からバックシールドガスを流し続けることは、コストが上昇するとともに、対象とする鋼材が例えば管材である場合は、作業が煩雑になるという問題点がある。 When gas-shielded arc welding steel materials with high Cr content such as those described above to form one-sided butt welded joints, back shielding with inert gas is required for the first layer of welding to prevent poor appearance of the back bead due to the formation of high-melting-point Cr oxides on the back surface. However, continuously flowing back shielding gas from the back side of the steel material increases costs and, when the steel material in question is, for example, pipe material, there are problems in that the work becomes complicated.
　特許文献１には、バックシールドガスを使用することなく、優れた裏波性能及び機械的性能を有する溶接部を施工しうる溶接材料が開示されている。上記特許文献１に記載の溶接材料は、Ｃ、Ｃｒ、Ｍｏ、Ｎｉ及びＡｌの含有量が規定され、Ｃｒ及びＭｎ含有量とＳｉ含有量との関係、Ｓ含有量とＭｎ含有量との関係、Ａｌ含有量とＯ含有量との合計量が制御されているとともに、不純物中のＰおよびＳの含有量が規定されたものである。 Patent Document 1 discloses a welding material that can produce welds with excellent back-sealing and mechanical properties without using back shielding gas. The welding material described in Patent Document 1 has specified contents of C, Cr, Mo, Ni, and Al, and the relationship between the Cr and Mn contents and the Si content, the relationship between the S content and the Mn content, and the total amount of the Al content and the O content are controlled, and the contents of P and S in the impurities are specified.
日本国特開平１０－２４３８８号公報Japanese Patent Application Publication No. 10-24388
　ところで、９Ｃｒ－１Ｍｏ－Ｎｂ－Ｖ鋼のようなフェライト系高強度耐熱鋼の溶接金属には、じん性の改善等を目的として溶接後熱処理（ＰＷＨＴ：Ｐｏｓｔ　Ｗｅｌｄ　Ｈｅａｔ　Ｔｒｅａｔｍｅｎｔ）が施されることがある。しかしながら、上記特許文献１に記載の溶接材料では、高温変態温度（Ａｃ１変態点）が検討されておらず、ＰＷＨＴの温度によっては、溶接金属のじん性を確保することができない可能性がある。また、裏波性能及び初層の機械的性能についても、更なる改善の余地があった。 Incidentally, the weld metal of ferritic high-strength heat-resistant steel such as 9Cr-1Mo-Nb-V steel may be subjected to post-weld heat treatment (PWHT) for the purpose of improving toughness, etc. However, the high-temperature transformation temperature (Ac1 transformation point) has not been considered in the welding material described in the above Patent Document 1, and depending on the PWHT temperature, it may not be possible to ensure the toughness of the weld metal. In addition, there is room for further improvement in the back-strip performance and the mechanical performance of the first layer.
　さらに、特許文献１においては、δフェライトの生成抑制についても十分に考慮されておらず、火力発電、原子力発電のボイラや圧力容器等に十分に対応できる溶接金属を形成するためには、δフェライトの生成をより一層抑制することが重要となる。 Furthermore, Patent Document 1 does not fully consider the suppression of the formation of δ-ferrite, and in order to form weld metal that is adequate for use in boilers and pressure vessels for thermal and nuclear power plants, it is important to further suppress the formation of δ-ferrite.
　本発明は、上述した問題点に鑑みてなされたものであり、１質量％以上１０質量％以下のＣｒを含有する鋼材の溶接に用いられ、バックシールドガスを使用することなく、優れた外観の裏波を得ることができるとともに、優れた機械的性能を有する溶接金属を得ることができるソリッドワイヤ、及びガスシールドアーク溶接方法を提供することを目的とする。 The present invention was made in consideration of the above-mentioned problems, and aims to provide a solid wire and a gas-shielded arc welding method that can be used to weld steel containing 1% to 10% by mass of Cr, and that can produce a back wave with excellent appearance without using back shielding gas, and can also produce a weld metal with excellent mechanical properties.
　本発明者らは、上記課題を解決するために鋭意研究した結果、裏波の形成不良の発生を抑制するために、特に、ソリッドワイヤ中のＳｉ含有量を制御することが重要であることを見出した。また、本発明者らは、ソリッドワイヤ中のＮｂ、Ｖ及びＣｏの含有量を制御することにより、δフェライトの生成を抑制し、所望の機械的特性を有する溶接金属を得ることができることを見出した。本発明は、この知見に基づいてなされたものである。 As a result of intensive research conducted by the inventors to solve the above problems, they discovered that in order to suppress the occurrence of poor formation of the uranami, it is particularly important to control the Si content in the solid wire. Furthermore, they discovered that by controlling the Nb, V and Co contents in the solid wire, it is possible to suppress the formation of δ-ferrite and obtain a weld metal with the desired mechanical properties. The present invention was made based on this knowledge.
　本発明の上記目的は、ソリッドワイヤに係る下記（１）の構成により達成される。 The above object of the present invention is achieved by the following configuration (1) relating to solid wire.
（１）　１質量％以上１０質量％以下のＣｒを含有する鋼材の溶接に用いられるソリッドワイヤであって、
　ワイヤ全質量に対して、
　Ｃ：０．０５質量％以上０．１５質量％以下、
　Ｓｉ：０．８質量％以上１．７質量％以下、
　Ｍｎ：０．４質量％以上１．２質量％以下、
　Ｃｒ：７．５質量％以上１３．０質量％以下、
　Ｍｏ：０．７０質量％以上１．５質量％以下、
　Ｎｂ：０．０１０質量％以上０．１０質量％以下、
　Ｖ：０．１０質量％以上０．５０質量％以下、
　Ｎ：０．０１０質量％以上０．０７０質量％以下を含有し、
　Ｐ：０．０３０質量％以下、
　Ｓ：０．０３０質量％以下、
　Ｎｉ：０．８０質量％以下、
　Ｔｉ：０．０２５質量％以下、
　Ａｌ：０．０２０質量％以下、
　Ｃｏ：０．７０質量％以下、であり、
　残部がＦｅ及び不可避的不純物からなることを特徴とするソリッドワイヤ。 (1) A solid wire used for welding steel materials containing 1 mass% or more and 10 mass% or less of Cr,
For the total mass of wire,
C: 0.05% by mass or more and 0.15% by mass or less,
Si: 0.8% by mass or more and 1.7% by mass or less,
Mn: 0.4% by mass or more and 1.2% by mass or less,
Cr: 7.5% by mass or more and 13.0% by mass or less,
Mo: 0.70% by mass or more and 1.5% by mass or less,
Nb: 0.010% by mass or more and 0.10% by mass or less,
V: 0.10% by mass or more and 0.50% by mass or less,
N: 0.010% by mass or more and 0.070% by mass or less;
P: 0.030% by mass or less,
S: 0.030% by mass or less,
Ni: 0.80 mass% or less,
Ti: 0.025% by mass or less,
Al: 0.020% by mass or less,
Co: 0.70% by mass or less;
The balance of the solid wire is Fe and unavoidable impurities.
　また、ソリッドワイヤに係る本発明の好ましい実施形態は、以下の（２）及び（３）に関する。 Furthermore, preferred embodiments of the present invention relating to solid wires relate to (2) and (3) below.
（２）　さらに、ワイヤ全質量に対して、
　Ｚｒ：０．１０質量％以下、
を含有することを特徴とする、（１）に記載のソリッドワイヤ。 (2) Furthermore, with respect to the total mass of the wire,
Zr: 0.10 mass% or less,
The solid wire according to (1), comprising:
（３）　さらに、ワイヤ全質量に対して、
　Ｃｕ：０．５０質量％以下、
を含有することを特徴とする、（１）又は（２）に記載のソリッドワイヤ。 (3) Furthermore, with respect to the total mass of the wire,
Cu: 0.50% by mass or less,
The solid wire according to (1) or (2), comprising:
　本発明の上記目的は、ガスシールドアーク溶接方法に係る下記（４）の構成により達成される。 The above object of the present invention is achieved by the following configuration (4) of the gas shielded arc welding method.
（４）　１質量％以上１０質量％以下のＣｒを含有する鋼材に対して、（１）～（３）のいずれか１つに記載のソリッドワイヤを用いて、バックシールドガスを使用せずに溶接することを特徴とするガスシールドアーク溶接方法。 (4) A gas-shielded arc welding method for welding steel containing 1% by mass or more and 10% by mass or less of Cr using a solid wire described in any one of (1) to (3) without using a back shielding gas.
　本発明によれば、バックシールドガスを使用することなく、優れた外観の裏波を得ることができるとともに、優れた機械的性能を有する溶接金属を得ることができるソリッドワイヤ、及びこのソリッドワイヤを使用したガスシールドアーク溶接方法を提供することができる。 The present invention provides a solid wire that can produce a back wave with excellent appearance without using back shielding gas, and can also produce a weld metal with excellent mechanical properties, as well as a gas-shielded arc welding method that uses this solid wire.
　以下、本発明を実施するための形態について詳細に説明する。なお、本明細書において、ソリッドワイヤを、単に「ワイヤ」ということがある。また、本発明は、以下に説明する実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲において、任意に変更して実施することができる。 Below, the embodiments for implementing the present invention will be described in detail. In this specification, solid wire may be simply referred to as "wire." Furthermore, the present invention is not limited to the embodiments described below, and can be modified as desired without departing from the gist of the present invention.
〔ソリッドワイヤ〕
　本実施形態に係るソリッドワイヤは、１質量％以上１０質量％以下のＣｒを含有する鋼材の溶接に用いられる。例えば、９％Ｃｒ鋼と２％Ｃｒ鋼との組合せで被溶接鋼材を構成することができ、本実施形態に係るソリッドワイヤは、異材継手にも適用することができる。本実施形態に係るソリッドワイヤは、９Ｃｒ－１Ｍｏ－Ｎｂ－Ｖ鋼の溶接に用いられることが特に好ましい。 [Solid wire]
The solid wire according to the present embodiment is used for welding steel materials containing 1% by mass or more and 10% by mass or less of Cr. For example, a combination of 9% Cr steel and 2% Cr steel can be used to form a welded steel material, and the solid wire according to the present embodiment can also be applied to dissimilar material joints. The solid wire according to the present embodiment is particularly preferably used for welding 9Cr-1Mo-Nb-V steel.
　以下、Ｃｒ含有量が８質量％以上１０質量％以下であるものを、９％Ｃｒ鋼ということがある。本実施形態において、被溶接鋼材として使用する鋼材の形状は特に限定されず例えば鋼板や鋼管等の溶接に適用することができる。 Hereinafter, a Cr content of 8% by mass or more and 10% by mass or less may be referred to as 9% Cr steel. In this embodiment, the shape of the steel material used as the steel material to be welded is not particularly limited, and it can be used, for example, to weld steel plates, steel pipes, etc.
　本実施形態に係るソリッドワイヤに含有される化学成分について、その含有理由及び数値限定理由を以下に詳細に説明する。 The chemical components contained in the solid wire according to this embodiment are explained in detail below, along with the reasons for their inclusion and the reasons for the numerical limitations.
＜Ｃ：０．０５質量％以上０．１５質量％以下＞
　Ｃは、Ｃｒ、Ｍｏ、Ｖ及びＮｂと結合して炭化物を形成し、溶接金属の強度を確保する効果を有する重要な元素である。さらにオーステナイト形成元素として溶接金属におけるδフェライトの生成抑制に寄与する。ワイヤ全質量に対するＣ含有量が０．０５質量％未満であると、溶接金属の所望の強度を得ることができない。したがって、ワイヤ全質量に対するＣ含有量は０．０５質量％以上とし、０．０６質量％以上であることが好ましく、０．０７質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＣ含有量が０．１５質量％を超えると、偏析部の凝固温度が大きく低下し、高温割れが発生しやすくなる。また、炭化物の析出が過剰となり、溶接金属のじん性が低下する。したがって、ワイヤ全質量に対するＣ含有量は０．１５質量％以下とし、０．１４質量％以下であることが好ましく、０．１３質量％以下であることがより好ましい。 <C: 0.05% by mass or more and 0.15% by mass or less>
C is an important element that combines with Cr, Mo, V, and Nb to form carbides and ensure the strength of the weld metal. Furthermore, as an austenite-forming element, C contributes to suppressing the formation of δ-ferrite in the weld metal. If the C content relative to the total mass of the wire is less than 0.05 mass%, the desired strength of the weld metal cannot be obtained. Therefore, the C content relative to the total mass of the wire is set to 0.05 mass% or more, preferably 0.06 mass% or more, and more preferably 0.07 mass% or more.
On the other hand, if the C content exceeds 0.15% by mass relative to the total mass of the wire, the solidification temperature of the segregation portion is significantly lowered, and hot cracking is likely to occur. In addition, carbide is excessively precipitated, and the toughness of the weld metal is reduced. Therefore, the C content relative to the total mass of the wire is set to 0.15% by mass or less, preferably 0.14% by mass or less, and more preferably 0.13% by mass or less.
＜Ｓｉ：０．８質量％以上１．７質量％以下＞
　Ｓｉは、裏波表面に低融点かつ溶接金属の凝固を阻害しにくい酸化被膜を優先的に形成し、溶接時のＣｒの酸化による裏波形成不良を防ぐ効果を有する。ワイヤ全質量に対するＳｉ含有量が０．８質量％未満であると、上記効果を十分に得ることができず、裏波形状が劣化する。したがって、ワイヤ全質量に対するＳｉ含有量は０．８質量％以上とし、０．９質量％以上であることが好ましく、１．０質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＳｉ含有量が１．７質量％を超えると、溶接金属においてδフェライトが過剰に生成され、溶接金属のじん性が低下する。また、表ビードへのスラグ発生量が多くなり、スラグ巻込みが発生しやすくなる。したがって、ワイヤ全質量に対するＳｉ含有量は１．７質量％以下とし、１．６質量％以下であることが好ましく、１．５質量％以下であることがより好ましい。 <Si: 0.8 mass% or more and 1.7 mass% or less>
Si has the effect of preferentially forming an oxide film on the uranami surface that has a low melting point and is unlikely to inhibit the solidification of the weld metal, and preventing poor uranami formation due to the oxidation of Cr during welding. If the Si content relative to the total mass of the wire is less than 0.8 mass%, the above effect cannot be sufficiently obtained and the uranami shape deteriorates. Therefore, the Si content relative to the total mass of the wire is set to 0.8 mass% or more, preferably 0.9 mass% or more, and more preferably 1.0 mass% or more.
On the other hand, if the Si content exceeds 1.7 mass% relative to the total mass of the wire, an excessive amount of δ-ferrite is formed in the weld metal, which reduces the toughness of the weld metal. Also, the amount of slag generated in the surface bead increases, which makes slag inclusion more likely to occur. Therefore, the Si content relative to the total mass of the wire is set to 1.7 mass% or less, preferably 1.6 mass% or less, and more preferably 1.5 mass% or less.
＜Ｍｎ：０．４質量％以上１．２質量％以下＞
　Ｍｎは、溶接金属の脱酸剤として機能し、溶接金属の強度を向上させ、じん性を改善する効果を有する元素である。また、Ｍｎは、オーステナイト形成元素であり、溶接金属におけるδフェライトの生成抑制に寄与する。ワイヤ全質量に対するＭｎ含有量が０．４質量％未満であると、脱酸不足を引き起こすとともに、溶接金属中のδフェライト残留を抑制する効果を十分に得ることができず、溶接金属のじん性が低下する。したがって、ワイヤ全質量に対するＭｎ含有量は０．４質量％以上とし、０．５質量％以上であることが好ましく、０．６質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＭｎ含有量が１．２質量％を超えると、溶接金属の高温強度が劣化する。また、偏析部の凝固温度が低下するとともに、変態点が低下して、高温でのＰＷＨＴが困難となる。さらに、ＭｎがＣｒとともに複合酸化物を生成し、裏波形成不良を引き起こす。したがって、ワイヤ全質量に対するＭｎ含有量は１．２質量％以下とし、１．１質量％以下であることが好ましく、１．０質量％以下であることがより好ましい。 <Mn: 0.4 mass% or more and 1.2 mass% or less>
Mn functions as a deoxidizer for the weld metal, and is an element that has the effect of improving the strength and toughness of the weld metal. Mn is also an austenite-forming element, and contributes to suppressing the formation of δ-ferrite in the weld metal. If the Mn content relative to the total mass of the wire is less than 0.4 mass%, it causes insufficient deoxidation and is unable to fully suppress the residual δ-ferrite in the weld metal, resulting in a decrease in the toughness of the weld metal. Therefore, the Mn content relative to the total mass of the wire is set to 0.4 mass% or more, preferably 0.5 mass% or more, and more preferably 0.6 mass% or more.
On the other hand, if the Mn content exceeds 1.2 mass% relative to the total mass of the wire, the high-temperature strength of the weld metal deteriorates. In addition, the solidification temperature of the segregation part decreases, and the transformation point decreases, making PWHT at high temperatures difficult. Furthermore, Mn generates a complex oxide together with Cr, causing poor formation of the uranami. Therefore, the Mn content relative to the total mass of the wire is set to 1.2 mass% or less, preferably 1.1 mass% or less, and more preferably 1.0 mass% or less.
＜Ｃｒ：７．５質量％以上１３．０質量％以下＞
　Ｃｒは、本実施形態に係るソリッドワイヤを用いた溶接において、良好な裏波形成が困難である高Ｃｒ含有量の被溶接鋼材の主要元素であり、溶接金属の高温における耐酸化性や、高温強度を確保するために不可欠な元素である。ワイヤ全質量に対するＣｒ含有量が７．５質量％未満であると、溶接金属の耐酸化性及び高温強度が不十分となる。したがって、ワイヤ全質量に対するＣｒ含有量は７．５質量％以上とし、７．８質量％以上であることが好ましく、８．０質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＣｒ含有量が１３．０質量％を超えると、上述のとおりＳｉ含有量を制御した場合であっても、裏波表面に高融点溶接金属の均一な凝固を阻害する酸化被膜を生成する。また、Ｃｒはフェライト生成元素のため、δフェライトの残留を引き起こし、溶接金属のじん性やクリープ性能を劣化させる。したがって、ワイヤ全質量に対するＣｒ含有量は１３．０質量％以下とし、１２．５質量％以下であることが好ましく、１２．０質量％以下であることがより好ましい。 <Cr: 7.5 mass% or more and 13.0 mass% or less>
Cr is a main element of high Cr content welded steel material in which good uranami formation is difficult in welding using the solid wire according to this embodiment, and is an essential element for ensuring oxidation resistance at high temperatures and high-temperature strength of the weld metal. If the Cr content relative to the total mass of the wire is less than 7.5 mass%, the oxidation resistance and high-temperature strength of the weld metal become insufficient. Therefore, the Cr content relative to the total mass of the wire is set to 7.5 mass% or more, preferably 7.8 mass% or more, and more preferably 8.0 mass% or more.
On the other hand, if the Cr content exceeds 13.0% by mass relative to the total mass of the wire, even if the Si content is controlled as described above, an oxide film that inhibits uniform solidification of the high melting point weld metal is formed on the back surface. In addition, since Cr is a ferrite forming element, it causes δ ferrite to remain, which deteriorates the toughness and creep performance of the weld metal. Therefore, the Cr content relative to the total mass of the wire is set to 13.0% by mass or less, preferably 12.5% by mass or less, and more preferably 12.0% by mass or less.
＜Ｍｏ：０．７０質量％以上１．５質量％以下＞
　Ｍｏは、固溶強化元素であるとともに、炭化物の析出によって高温強度を高める効果を有する元素である。ワイヤ全質量に対するＭｏ含有量が０．７０質量％未満であると、溶接金属の高温強度が不十分となる。したがって、ワイヤ全質量に対するＭｏ含有量は０．７０質量％以上とし、０．７５質量％以上であることが好ましく、０．８０質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＭｏ含有量が１．５質量％を超えると、δフェライトの残留を引き起こし、溶接金属のじん性やクリープ性能が劣化する。したがって、ワイヤ全質量に対するＭｏ含有量は１．５質量％以下とし、１．３質量％以下であることが好ましく、１．２質量％以下であることがより好ましい。 <Mo: 0.70 mass% or more and 1.5 mass% or less>
Mo is a solid solution strengthening element and also has the effect of increasing high-temperature strength by precipitation of carbides. If the Mo content relative to the total mass of the wire is less than 0.70 mass%, the high-temperature strength of the weld metal becomes insufficient. Therefore, the Mo content relative to the total mass of the wire is set to 0.70 mass% or more, preferably 0.75 mass% or more, and more preferably 0.80 mass% or more.
On the other hand, if the Mo content exceeds 1.5 mass% relative to the total mass of the wire, it causes residual δ-ferrite, which deteriorates the toughness and creep performance of the weld metal. Therefore, the Mo content relative to the total mass of the wire is set to 1.5 mass% or less, preferably 1.3 mass% or less, and more preferably 1.2 mass% or less.
＜Ｎｂ：０．０１０質量％以上０．１０質量％以下＞
　Ｎｂは、固溶強化及び窒化物として析出することで溶接金属の強度を向上させる効果を有する元素である。ワイヤ全質量に対するＮｂ含有量が０．０１０質量％未満であると、溶接金属の強度を向上させる効果を十分に得ることができない。したがって、ワイヤ全質量に対するＮｂ含有量は０．０１０質量％以上とし、０．０１３質量％以上であることが好ましく、０．０１５質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＮｂ含有量が０．１０質量％を超えると、δフェライトの残留を引き起こし溶接金属のじん性を大きく劣化させる。したがって、ワイヤ全質量に対するＮｂ含有量は０．１０質量％以下とし、０．０９質量％以下であることが好ましく、０．０８質量％以下であることがより好ましい。 <Nb: 0.010 mass% or more and 0.10 mass% or less>
Nb is an element that has the effect of improving the strength of the weld metal by solid solution strengthening and precipitating as nitrides. If the Nb content relative to the total mass of the wire is less than 0.010 mass%, the effect of improving the strength of the weld metal cannot be sufficiently obtained. Therefore, the Nb content relative to the total mass of the wire is set to 0.010 mass% or more, preferably 0.013 mass% or more, and more preferably 0.015 mass% or more.
On the other hand, if the Nb content exceeds 0.10 mass% relative to the total mass of the wire, residual δ ferrite is caused, and the toughness of the weld metal is significantly deteriorated. Therefore, the Nb content relative to the total mass of the wire is set to 0.10 mass% or less, preferably 0.09 mass% or less, and more preferably 0.08 mass% or less.
＜Ｖ：０．１０質量％以上０．５０質量％以下＞
　Ｖは、炭窒化物として溶接金属中に析出し溶接金属の強度を向上させる効果を有する元素である。ワイヤ全質量に対するＶ含有量が０．１０質量％未満であると、溶接金属の強度を向上させる効果を十分に得ることができない。したがって、ワイヤ全質量に対するＶ含有量は０．１０質量％以上とし、０．１３質量％以上であることが好ましく、０．１５質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＶ含有量が０．５０質量％を超えると、δフェライトの残留を引き起こし溶接金属のじん性が劣化する。したがって、ワイヤ全質量に対するＶ含有量は０．５０質量％以下とし、０．４０質量％以下であることが好ましく、０．３０質量％以下であることがより好ましい。 <V: 0.10 mass% or more and 0.50 mass% or less>
V is an element that precipitates in the weld metal as a carbonitride and has the effect of improving the strength of the weld metal. If the V content relative to the total mass of the wire is less than 0.10 mass%, the effect of improving the strength of the weld metal cannot be sufficiently obtained. Therefore, the V content relative to the total mass of the wire is set to 0.10 mass% or more, preferably 0.13 mass% or more, and more preferably 0.15 mass% or more.
On the other hand, if the V content exceeds 0.50 mass% relative to the total mass of the wire, residual δ ferrite is caused and the toughness of the weld metal is deteriorated. Therefore, the V content relative to the total mass of the wire is set to 0.50 mass% or less, preferably 0.40 mass% or less, and more preferably 0.30 mass% or less.
＜Ｎ：０．０１０質量％以上０．０７０質量％以下＞
　Ｎは、固溶強化及び窒化物として析出して強度の安定化に寄与する元素である。また、オーステナイト形成元素であり、溶接金属中のδフェライトを抑制する効果を有する元素である。ワイヤ全質量に対するＮ含有量が０．０１０質量％未満であると上記効果を十分に得ることができず、強度が低下しδフェライトが生成される。したがって、ワイヤ全質量に対するＮ含有量は０．０１０質量％以上とし、０．０１５質量％以上であることが好ましく、０．０２０質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＮ含有量が０．０７０質量％を超えると、ブローホールが発生する。したがって、ワイヤ全質量に対するＮ含有量は０．０７０質量％以下とし、０．０６５質量％以下であることが好ましく、０．０６０質量％以下であることがより好ましい。 <N: 0.010 mass% or more and 0.070 mass% or less>
N is an element that contributes to solid solution strengthening and stabilization of strength by precipitating as nitrides. It is also an austenite forming element and has the effect of suppressing δ-ferrite in the weld metal. If the N content relative to the total mass of the wire is less than 0.010 mass%, the above effect cannot be sufficiently obtained, the strength is reduced, and δ-ferrite is generated. Therefore, the N content relative to the total mass of the wire is set to 0.010 mass% or more, preferably 0.015 mass% or more, and more preferably 0.020 mass% or more.
On the other hand, if the N content with respect to the total mass of the wire exceeds 0.070 mass%, blowholes occur. Therefore, the N content with respect to the total mass of the wire is set to 0.070 mass% or less, preferably 0.065 mass% or less, and more preferably 0.060 mass% or less.
＜Ｐ：０．０３０質量％以下＞
　Ｐは、不純物元素であり、高温割れ感受性を高める成分である。ワイヤ全質量に対するＰ含有量が０．０３０質量％を超えると、高温割れの発生が懸念される。したがって、ワイヤ全質量に対するＰ含有量は０．０３０質量％以下とし、０．０２０質量％以下であることが好ましく、０．０１５質量％以下であることがより好ましい。 <P: 0.030 mass% or less>
P is an impurity element and a component that increases hot cracking susceptibility. If the P content with respect to the total mass of the wire exceeds 0.030 mass%, there is a concern that hot cracking may occur. Therefore, the P content with respect to the total mass of the wire is set to 0.030 mass% or less, preferably 0.020 mass% or less, and more preferably 0.015 mass% or less.
＜Ｓ：０．０３０質量％以下＞
　Ｓは、溶融池内の対流に影響を与え、溶込み深さを増加させるとともに、アークの安定性を向上させ、良好な裏波を形成する効果を有する。本実施形態においてＳ含有量の下限は特に限定されず、０質量％であってもよいが、より一層裏波形成能を向上させることを目的としてワイヤ中にＳを含有させる場合に、ワイヤ全質量に対するＳ含有量は０．００３質量％以上であることが好ましく、０．００５質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＳ含有量が０．０３０質量％を超えると、高温割れの発生が懸念される。したがって、ワイヤ全質量に対するＳ含有量は０．０３０質量％以下とし、０．０２５質量％以下であることが好ましく、０．０２０質量％以下であることがより好ましい。 <S: 0.030 mass% or less>
S has the effect of affecting convection in the molten pool, increasing the penetration depth, improving the stability of the arc, and forming a good backside wave. In this embodiment, the lower limit of the S content is not particularly limited and may be 0 mass %, but when S is contained in the wire for the purpose of further improving the backside wave formation ability, the S content relative to the total mass of the wire is preferably 0.003 mass % or more, and more preferably 0.005 mass % or more.
On the other hand, if the S content exceeds 0.030% by mass relative to the total mass of the wire, there is a concern that hot cracks may occur. Therefore, the S content relative to the total mass of the wire is set to 0.030% by mass or less, preferably 0.025% by mass or less, and more preferably 0.020% by mass or less.
＜Ｎｉ：０．８０質量％以下＞
　Ｎｉは、Ｍｎと同様にオーステナイト形成元素であり、溶接金属におけるδフェライトの生成抑制に寄与する。本実施形態においてＮｉ含有量の下限は特に限定されず、０質量％であってもよいが、溶接金属中のδフェライトの生成を抑制する目的としてワイヤ中にＮｉを含有させる場合に、ワイヤ全質量に対するＮｉ含有量は０．０５質量％以上であることが好ましく、０．１０質量％以上であることがより好ましい。
　一方、ワイヤ全質量に対するＮｉ含有量が０．８０質量％を超えると、溶接金属の高温強度が劣化する。また、変態点が低下して、高温でのＰＷＨＴが困難となる。したがって、ワイヤ全質量に対するＮｉ含有量は０．８０質量％以下とし、０．６０質量％以下であることが好ましく、０．５０質量％以下であることがより好ましい。 <Ni: 0.80 mass% or less>
Ni, like Mn, is an austenite-forming element and contributes to suppressing the formation of δ-ferrite in the weld metal. In the present embodiment, the lower limit of the Ni content is not particularly limited and may be 0 mass%, but when Ni is contained in the wire for the purpose of suppressing the formation of δ-ferrite in the weld metal, the Ni content relative to the total mass of the wire is preferably 0.05 mass% or more, and more preferably 0.10 mass% or more.
On the other hand, if the Ni content exceeds 0.80 mass% relative to the total mass of the wire, the high-temperature strength of the weld metal deteriorates. Also, the transformation point decreases, making PWHT at high temperatures difficult. Therefore, the Ni content relative to the total mass of the wire is set to 0.80 mass% or less, preferably 0.60 mass% or less, and more preferably 0.50 mass% or less.
＜Ｔｉ：０．０２５質量％以下＞
　Ｔｉは、溶接金属の均一な凝固を阻害する酸化被膜を生成し、良好な裏波形状の生成を劣化させる。ワイヤ全質量に対するＴｉ含有量が０．０２５質量％を超えると、裏波形状が劣化する。したがって、ワイヤ全質量に対するＴｉ含有量は０．０２５質量％以下とし、０．０１８質量％以下であることが好ましく、０．０１５質量％以下であることがより好ましい。 <Ti: 0.025 mass% or less>
Ti forms an oxide film that inhibits uniform solidification of the weld metal, and deteriorates the formation of a good back bead shape. If the Ti content exceeds 0.025 mass% relative to the total mass of the wire, the back bead shape deteriorates. Therefore, the Ti content relative to the total mass of the wire is set to 0.025 mass% or less, preferably 0.018 mass% or less, and more preferably 0.015 mass% or less.
＜Ａｌ：０．０２０質量％以下＞
　Ａｌは、Ｓｉとともに、裏波表面に低融点かつ溶接金属の凝固を阻害しにくい酸化被膜を優先的に形成する元素であるが、スラグ生成能が高いため、スラグ巻込みを生じさせる懸念がある。また、Ａｌはフェライト生成元素であり、溶接金属においてδフェライトが過剰に生成され溶接金属のじん性が低下する。さらに、ＡｌはＮｂ、Ｖよりも優先的に窒化物を形成するため、高温強度を確保する効果を有するＮｂ、Ｖ窒化物の生成を阻害し、高温強度の低下を招く。したがって、ワイヤ全質量に対するＡｌ含有量は０．０２０質量％以下とし、０．０１５質量％以下であることが好ましく、０．０１２質量％以下であることがより好ましい。 <Al: 0.020 mass% or less>
Al, together with Si, is an element that preferentially forms an oxide film on the uranami surface that has a low melting point and does not inhibit the solidification of the weld metal, but has a high slag generating ability, so there is a concern that slag inclusion may occur. In addition, Al is a ferrite generating element, and excessive δ ferrite is generated in the weld metal, which reduces the toughness of the weld metal. Furthermore, Al preferentially forms nitrides over Nb and V, and therefore inhibits the generation of Nb and V nitrides that have the effect of ensuring high-temperature strength, resulting in a decrease in high-temperature strength. Therefore, the Al content of the wire is set to 0.020 mass% or less, preferably 0.015 mass% or less, and more preferably 0.012 mass% or less.
＜Ｃｏ：０．７０質量％以下＞
　Ｃｏは、ＮｉやＭｎと同様にオーステナイト形成元素であり、溶接金属におけるδフェライトの生成抑制に寄与する元素であり、ワイヤ中にＣｏを含有させることにより、溶接金属の所望の機械的性能を得ることができる。本実施形態においてＣｏ含有量の下限は特に限定されず、０質量％であってもよいが、溶接金属中のδフェライトの生成を抑制する目的としてワイヤ中にＣｏを含有させる場合に、ワイヤ全質量に対するＣｏ含有量は０．００５質量％であることが好ましく、０．０５質量％以上であることがより好ましく、０．１０質量％以上であることがさらに好ましく、０．１５質量％以上であることが特に好ましい。
　一方、ワイヤ全質量に対するＣｏ含有量が０．７０質量％を超えると、変態点が低下し、高温でのＰＷＨＴが困難となる。したがって、ワイヤ全質量に対するＣｏ含有量は０．７０質量％以下とし、０．６０質量％以下であることが好ましく、０．５０質量％以下であることがより好ましい。 <Co: 0.70 mass% or less>
Co is an austenite-forming element like Ni and Mn, and contributes to suppressing the formation of δ-ferrite in the weld metal, and the desired mechanical performance of the weld metal can be obtained by including Co in the wire. In this embodiment, the lower limit of the Co content is not particularly limited and may be 0 mass%, but when Co is included in the wire for the purpose of suppressing the formation of δ-ferrite in the weld metal, the Co content relative to the total mass of the wire is preferably 0.005 mass%, more preferably 0.05 mass% or more, even more preferably 0.10 mass% or more, and particularly preferably 0.15 mass% or more.
On the other hand, if the Co content exceeds 0.70% by mass relative to the total mass of the wire, the transformation point decreases, making it difficult to perform PWHT at high temperatures. Therefore, the Co content relative to the total mass of the wire is set to 0.70% by mass or less, preferably 0.60% by mass or less, and more preferably 0.50% by mass or less.
　本実施形態に係るソリッドワイヤは、上記成分以外に、以下に示す範囲でＺｒ及びＣｕのいずれか一方又は両方を含有していてもよい。ワイヤがさらに含有していてもよい成分の含有量及びその限定理由について、以下に説明する。 In addition to the above components, the solid wire according to this embodiment may contain either Zr or Cu or both within the ranges shown below. The contents of other components that the wire may further contain and the reasons for limiting them are explained below.
＜Ｚｒ：０．１０質量％以下＞
　Ｚｒは、Ｓｉとともに、裏波表面に溶接金属の凝固を阻害しにくい酸化被膜を優先的に形成する元素であるため、本実施形態に係るソリッドワイヤに、必要に応じてＺｒを含有させることが好ましい。ワイヤ中に０．１０質量％以下の範囲でＺｒを含有させると、δフェライトの過剰な生成によってじん性を低下させることなく、溶接時のＣｒの酸化による裏波形成不良を防ぐことができる。したがって、本実施形態に係るソリッドワイヤにＺｒを含有させる場合に、ワイヤ全質量に対するＺｒ含有量は０．１０質量％以下とし、０．０８質量％以下が好ましく０．０７質量％以下であることがより好ましい。
　一方、上記効果を得るためにワイヤ中にＺｒを含有させる場合は、ワイヤ全質量に対するＺｒ含有量は０．００５質量％以上であることが好ましく、０．０１０質量％以上であることがより好ましい。 <Zr: 0.10 mass% or less>
Zr, together with Si, is an element that preferentially forms an oxide film on the uranami surface that does not easily inhibit the solidification of the weld metal, so it is preferable to include Zr in the solid wire according to the present embodiment as necessary. If Zr is included in the wire in the range of 0.10 mass% or less, poor uranami formation due to oxidation of Cr during welding can be prevented without reducing toughness due to excessive generation of δ ferrite. Therefore, when Zr is included in the solid wire according to the present embodiment, the Zr content relative to the total mass of the wire is 0.10 mass% or less, preferably 0.08 mass% or less, and more preferably 0.07 mass% or less.
On the other hand, when Zr is contained in the wire in order to obtain the above-mentioned effect, the Zr content relative to the total mass of the wire is preferably 0.005 mass % or more, and more preferably 0.010 mass % or more.
＜Ｃｕ：０．５０質量％以下＞
　Ｃｕは、いずれもＮｉやＭｎと同様にオーステナイト形成元素であり、溶接金属におけるδフェライトの生成抑制に寄与する元素であるため、本実施形態に係るソリッドワイヤに、必要に応じてＣｕを含有させることが好ましい。ワイヤ中に０．５０質量％以下の範囲でＣｕを含有させると、溶接金属の高温強度を劣化させることなく、所望の機械的性能を有する溶接金属を得ることができる。したがって、本実施形態に係るソリッドワイヤにＣｕを含有させる場合に、ワイヤ全質量に対するＣｕ含有量は０．５０質量％以下とすることが好ましく、０．４０質量％以下であることがより好ましく、０．３０質量％以下であることがさらに好ましい。
　一方、上記効果を得るためにワイヤ中にＣｕを含有させる場合は、ワイヤ全質量に対するＣｕ含有量は０．０１質量％以上であることが好ましく、０．０５質量％以上であることがより好ましく、０．１０質量％以上であることがさらに好ましい。なお、本実施形態のワイヤはＣｕめっきが施されていてもよく、Ｃｕ含有量は銅めっき分も含むものとする。 <Cu: 0.50 mass% or less>
Since Cu is an austenite forming element like Ni and Mn, and contributes to suppressing the formation of δ-ferrite in the weld metal, it is preferable to contain Cu in the solid wire according to the present embodiment as necessary. When Cu is contained in the wire in the range of 0.50 mass% or less, it is possible to obtain a weld metal having the desired mechanical performance without deteriorating the high-temperature strength of the weld metal. Therefore, when Cu is contained in the solid wire according to the present embodiment, the Cu content relative to the total mass of the wire is preferably 0.50 mass% or less, more preferably 0.40 mass% or less, and even more preferably 0.30 mass% or less.
On the other hand, when Cu is contained in the wire to obtain the above-mentioned effect, the Cu content relative to the total mass of the wire is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.10 mass% or more. Note that the wire of this embodiment may be Cu-plated, and the Cu content includes the copper plating.
＜残部：Ｆｅ及び不可避的不純物＞
　本実施形態に係るソリッドワイヤの残部は、Ｆｅ及び不可避的不純物である。不可避的不純物とは、ワイヤ中に意図的に添加されていないものを意味し、上記以外の元素として、例えばＢ、Ｓｎ、Ａｓ、Ｓｂ等が挙げられる。ソリッドワイヤ中の不純物の含有量は、合計で０．１０質量％以下であることが好ましく、０．０５質量％以下であることがより好ましい。 <Balance: Fe and inevitable impurities>
The balance of the solid wire according to the present embodiment is Fe and inevitable impurities. The inevitable impurities refer to elements that are not intentionally added to the wire, and examples of elements other than those mentioned above include B, Sn, As, Sb, etc. The total content of impurities in the solid wire is preferably 0.10 mass% or less, and more preferably 0.05 mass% or less.
〔ガスシールドアーク溶接方法〕
　本実施形態に係るガスシールドアーク溶接方法は、１質量％以上１０質量％以下のＣｒを含有する被溶接鋼材に対して、上記ソリッドワイヤを用いて、バックシールドガスを使用せずに溶接する溶接方法である。上述のとおり、被溶接鋼材のＣｒ含有量が、例えば８質量％～１０質量％である場合に、従来のソリッドワイヤを使用して溶接すると、裏波が酸化しやすくなり、裏波の形状及び外観が劣化する。しかし、少なくとも初層の溶接として、上記本実施形態に係るソリッドワイヤを使用することにより、特に裏波が酸化しやすい高Ｃｒ含有量の鋼材のみでなく、１質量％以上１０質量％以下のＣｒを含有する被溶接鋼材に対して、バックシールドガスを使用せずに、優れた裏波性能及び機械的性能を有する裏波を形成することができる。 [Gas shielded arc welding method]
The gas-shielded arc welding method according to the present embodiment is a welding method for welding steel materials containing 1% by mass or more and 10% by mass or less of Cr using the above-mentioned solid wire without using back shield gas. As described above, when the Cr content of the steel materials to be welded is, for example, 8% by mass to 10% by mass, if a conventional solid wire is used for welding, the back wave is easily oxidized, and the shape and appearance of the back wave deteriorate. However, by using the solid wire according to the present embodiment as at least the first layer of welding, a back wave having excellent back wave performance and mechanical performance can be formed not only for steel materials with a high Cr content in which the back wave is particularly easily oxidized, but also for steel materials containing 1% by mass to 10% by mass or less of Cr, without using back shield gas.
　なお、本実施形態に係るガスシールドアーク溶接方法において、溶接の種類は特に限定されず、ティグ（ＴＩＧ：Ｔｕｎｇｓｔｅｎ　Ｉｎｅｒｔ　Ｇａｓ）溶接の他に、マグ（ＭＡＧ：Ｍｅｔａｌ　Ａｃｔｉｖｅ　Ｇａｓ）溶接、ミグ（ＭＩＧ：Ｍｅｔａｌ　Ｉｎｅｒｔ　Ｇａｓ）溶接を使用することができる。 In the gas-shielded arc welding method according to this embodiment, the type of welding is not particularly limited, and in addition to TIG (Tungsten Inert Gas) welding, MAG (Metal Active Gas) welding and MIG (Metal Inert Gas) welding can be used.
＜シールドガスの種類及び流量＞
　本実施形態に係るソリッドワイヤによる溶接時に、表側において使用するシールドガスは特に制限されないが、例えばＡｒガス、炭酸ガス、Ａｒガスと炭酸ガスの混合ガス、Ａｒガスと酸素ガスの混合ガスを用いることができる。ガスの流量も特に制限されないが、例えば１５～５０Ｌ／分とすることができる。 <Type and flow rate of shielding gas>
The shielding gas used on the front side during welding with the solid wire according to this embodiment is not particularly limited, but may be, for example, Ar gas, carbon dioxide gas, a mixed gas of Ar gas and carbon dioxide gas, or a mixed gas of Ar gas and oxygen gas. The flow rate of the gas is also not particularly limited, but may be, for example, 15 to 50 L/min.
＜溶接姿勢、ワイヤ径＞
　また、本実施形態に係るソリッドワイヤを使用した溶接姿勢は特に限定されず、種々の溶接姿勢で溶接を実施することができる。さらに、本実施形態に係るソリッドワイヤのワイヤ径（直径）についても、特に限定されないが、ＡＷＳ又はＪＩＳ等の溶接材料規格に規定された直径のワイヤに適用することができる。 <Welding position, wire diameter>
In addition, the welding position using the solid wire according to the present embodiment is not particularly limited, and welding can be performed in various welding positions. Furthermore, the wire diameter (diameter) of the solid wire according to the present embodiment is not particularly limited, but it can be applied to a wire having a diameter specified in a welding material standard such as AWS or JIS.
　以下、本発明に係る発明例及び比較例を挙げて、本発明の効果を具体的に説明するが、本発明はこれに限定されるものではない。 The effects of the present invention will be specifically explained below using examples of the present invention and comparative examples, but the present invention is not limited to these.
［ソリッドワイヤの製造］
　ワイヤの含有成分が種々の含有量となるように、ソリッドワイヤを作製した。ワイヤ全質量あたりの化学成分の含有量（質量％）を下記表１に示す。なお、ワイヤ中の下記表１に示す化学成分を除く残部は、Ｆｅ及び不可避的不純物である。 [Solid wire manufacturing]
Solid wires were prepared so that the wires contained various amounts of the components. The amounts (mass%) of the chemical components per total mass of the wires are shown in Table 1 below. The remainder of the wires, excluding the chemical components shown in Table 1 below, is Fe and unavoidable impurities.
［ガスシールドアーク溶接（裏波評価用）］
　裏波の評価のための溶接を実施した。具体的には、板厚：１９ｍｍ、鋼種：ＡＳＴＭ　Ａ３８７　Ｇｒａｄｅ９１　Ｃｌａｓｓ２、開先角度：７０°の一対の鋼板を準備し、ティグ溶接により初層を形成した。溶接条件を以下に示す。 [Gas shielded arc welding (for back wave evaluation)]
Welding was carried out to evaluate the reverse side of the welded joint. Specifically, a pair of steel plates having a plate thickness of 19 mm, a steel type of ASTM A387 Grade 91 Class 2, and a groove angle of 70° were prepared, and a first layer was formed by TIG welding. The welding conditions are as follows.
＜溶接条件＞
　溶接方法：ティグ溶接
　ワイヤ径：２．４ｍｍ
　ルートギャップ：２～３ｍｍ
　溶接電流：９０～１１０Ａ
　アーク電圧：１０～１４Ｖ
　予熱：１５０～３００℃
　シールドガスの種類、流量：１００％Ａｒ、１５リットル／分
　バックシールドガス：無し
　溶接姿勢：下向 <Welding conditions>
Welding method: TIG welding Wire diameter: 2.4 mm
Root gap: 2-3mm
Welding current: 90-110A
Arc voltage: 10-14V
Preheat: 150-300℃
Shielding gas type and flow rate: 100% Ar, 15 liters/min. Back shielding gas: None. Welding position: Downward.
［裏波の評価試験］
＜評価項目＞
　各ソリッドワイヤを使用して得られた溶接金属について、溶接の裏側（裏波外観）を目視で観察するとともに、溶接金属の断面マクロを目視で観察し、裏波の評価を実施した。裏波の外観については、酸化の度合い、溶け落ちの有無及び凹ビードの有無を観察した。断面マクロについては、裏波の高さ、裏波の窪みの深さ、及び母材と裏波との境界部分の形状を観察した。各評価項目の測定結果及び評価結果を下記表２に示す。 [Uranami evaluation test]
<Evaluation items>
For the weld metal obtained using each solid wire, the back side of the weld (appearance of the back wave) was visually observed, and the cross-sectional macro of the weld metal was visually observed to evaluate the back wave. For the appearance of the back wave, the degree of oxidation, the presence or absence of burn-through, and the presence or absence of a concave bead were observed. For the cross-sectional macro, the height of the back wave, the depth of the depression in the back wave, and the shape of the boundary between the base metal and the back wave were observed. The measurement results and evaluation results for each evaluation item are shown in Table 2 below.
＜評価方法及び評価基準＞
（裏波の外観）
　裏波の外観については、裏波幅が揃っており、蛇行や凹凸が無いとともに、酸化による変色や凹凸がなく、さらに、溶け落ち及び凹ビードが確認されなかったものを良好とした。一方、裏波幅が不揃いであり、凹凸が激しいもの、裏波が酸化によって変色していたか若しくは凹凸が確認されたもの、又は、溶け落ち若しくは凹ビードが発生したものを不合格とし、不合格と判断されたものについては、測定結果の欄に外観の状態を記載した。 <Evaluation method and criteria>
(Exterior of Uranami)
Regarding the appearance of the back wave, those that had a uniform width, no meandering or unevenness, no discoloration or unevenness due to oxidation, and no burn-through or concave beads were confirmed were rated as good. On the other hand, those that had an uneven width and severe unevenness, those that had discoloration or unevenness due to oxidation, or those that had burn-through or concave beads were rated as failing, and for those that were judged to be failing, the appearance condition was recorded in the measurement results column.
（裏波の高さ）
　断面マクロ観察において、裏波の高さを測定した。本実施例においては、裏波の高さが０．５ｍｍ以上のものを合格とし、裏波の高さが０．５ｍｍ未満のものを不合格とし、測定結果の欄には裏波の高さを記載した。 (Height of back wave)
In the cross-sectional macro observation, the height of the back wave was measured. In this example, a back wave height of 0.5 mm or more was considered to be acceptable, and a back wave height of less than 0.5 mm was considered to be unacceptable. The height of the back wave was recorded in the measurement result column.
（窪みの深さ）
　裏波の幅方向端部付近について、窪みの有無を観察し、窪みがあるものについては窪みの深さを測定した。本実施例においては、母材裏面に対して０．５ｍｍ以上の深さの窪みがないものを合格とし、０．５ｍｍ以上の窪みが発生したものを不合格とし、測定結果の欄には窪みの深さを記載した。 (Depth of the recess)
The presence or absence of dents was observed near the widthwise end of the back side, and the depth of dents was measured for those that had dents. In this example, those that did not have dents with a depth of 0.5 mm or more on the back side of the base material were considered to have passed, and those that had dents of 0.5 mm or more were considered to have failed, and the depth of the dents was recorded in the measurement results column.
（母材と裏波との境界部分の形状）
　断面マクロにおいて母材と裏波との境界部分の形状を観察し、母材から裏波に向かってなだらかな凸形状になっているものを良好（合格）、母材と裏波との境界部分で、裏波が急激に盛り上がった凸形状となっているものを不良（不合格）と判断し、測定結果の欄には「良好」又は「不良」と記載した。なお、溶け落ちが発生したものについては、母材と裏波との境界部分で裏波が急激に盛り上がった凸形状となる傾向にあった。 (Shape of the boundary between the base material and the back wave)
The shape of the boundary between the base material and the back wave was observed in the cross section macro, and those with a gentle convex shape from the base material to the back wave were judged as good (passed), and those with a sudden convex shape at the boundary between the base material and the back wave were judged as bad (failed), and "good" or "bad" was entered in the measurement results column. Note that for those where burn-through occurred, there was a tendency for the back wave to suddenly rise convex at the boundary between the base material and the back wave.
（裏波の総合評価）
　そして、裏波の評価としては、上記全ての項目が合格であったものを、評価「Ａ」とし、１つ以上の項目が不合格であったものを、評価「Ｃ」とし、評価結果を裏波の評価結果欄に記載した。 (Overall rating of the back waves)
In assessing the back side of the wave, a wave that passed all of the above items was given a rating of "A", and a wave that failed one or more items was given a rating of "C", and the evaluation results were recorded in the back side evaluation result column.
［ガスシールドアーク溶接（溶接金属評価用）］
　溶接金属の評価のための溶接を実施した。具体的には、板厚が１２ｍｍである、ＪＩＳ　Ｇ３１０６：２０２０に記載のＳＭ４９０Ａ鋼材の開先角度を４５°に加工し、作製したソリッドワイヤを使用して開先内及び裏当て金を２層以上バタリングした後、ルート間隔を６．５ｍｍとして、ティグ溶接により多層溶接にて溶接金属を形成した。溶接条件を以下に示す。 [Gas shielded arc welding (for weld metal evaluation)]
Welding was carried out to evaluate the weld metal. Specifically, the groove angle of SM490A steel material described in JIS G3106:2020, which has a plate thickness of 12 mm, was processed to 45°, and the inside of the groove and the backing metal were buttered in two or more layers using the prepared solid wire, and then the weld metal was formed by multi-layer welding using TIG welding with a root spacing of 6.5 mm. The welding conditions are shown below.
＜溶接条件＞
　溶接方法：ティグ溶接
　ワイヤ径：１．２ｍｍ
　溶接電流：１６０～１８０Ａ
　アーク電圧：１０～１６Ｖ
　シールドガスの種類、流量：１００％Ａｒ、２５リットル／分
　溶接姿勢：下向
　ＰＷＨＴ温度、時間：７６０℃、２時間 <Welding conditions>
Welding method: TIG welding Wire diameter: 1.2 mm
Welding current: 160-180A
Arc voltage: 10-16V
Shielding gas type and flow rate: 100% Ar, 25 liters/min. Welding position: Downward PWHT temperature and time: 760°C, 2 hours
［溶接金属の機械的性能評価試験］
＜評価項目＞
　各ソリッドワイヤを使用して得られた溶接金属について、Ａｃ１変態点を測定することによりＰＷＨＴの温度設定の裕度を評価するとともに、δフェライトの面積率を測定した。また、引張試験及びシャルピー衝撃試験を実施することにより、機械的性能を評価した。各評価項目の測定結果及び評価結果を下記表２に併せて示す。なお、裏波が不良となったもののうち、一部の試験片に対しては、溶接金属の機械的性能評価試験を実施しなかった。 [Mechanical performance evaluation test of weld metal]
<Evaluation items>
For the weld metal obtained using each solid wire, the Ac1 transformation point was measured to evaluate the PWHT temperature setting tolerance, and the area ratio of δ-ferrite was measured. In addition, a tensile test and a Charpy impact test were performed to evaluate the mechanical performance. The measurement results and evaluation results for each evaluation item are shown in Table 2 below. Note that, for some test pieces with poor back-beam, the mechanical performance evaluation test of the weld metal was not performed.
＜評価方法及び評価基準＞
（Ａｃ１変態点の測定）
　得られたＰＷＨＴ前の溶接金属から、直径が８ｍｍ、長さが１２ｍｍである丸棒状の試験片を採取し、高周波誘導加熱方式による加熱中の試験片の体積変化を測定することにより、Ａｃ１変態点を測定した。
　なお、Ａｃ１変態点よりも高い温度でＰＷＨＴを実施した場合に、溶接金属が逆変態によって高強度、低じん性のフレッシュマルテンサイトを含有した組織となり、溶接継手性能が劣化するため、Ａｃ１変態点が高い方がＰＷＨＴの温度設定の裕度を大きくすることができる。したがって、評価基準としては、Ａｃ１変態点が８００℃以上であったものを評価「Ａ」（優良）とし、７８０℃以上、８００℃未満であったものを評価「Ｂ」（良好）とし、７８０℃未満であったものを評価「Ｃ」（不良）とした。 <Evaluation method and criteria>
(Measurement of Ac1 transformation point)
A round bar-shaped test piece having a diameter of 8 mm and a length of 12 mm was taken from the obtained weld metal before PWHT, and the Ac1 transformation point was measured by measuring the volume change of the test piece during heating by a high-frequency induction heating method.
In addition, when PWHT is performed at a temperature higher than the Ac1 transformation point, the weld metal undergoes reverse transformation to become a structure containing high-strength, low-toughness fresh martensite, and the performance of the welded joint deteriorates, so a higher Ac1 transformation point allows for a larger margin in the temperature setting of the PWHT. Therefore, as the evaluation criteria, those with an Ac1 transformation point of 800°C or higher were rated "A" (excellent), those with an Ac1 transformation point of 780°C or higher and less than 800°C were rated "B" (good), and those with an Ac1 transformation point of less than 780°C were rated "C" (poor).
（δフェライト面積率の測定）
　得られたＰＷＨＴ前の溶接金属から、溶接方向に直角方向の断面の最終パス原質部を含む１２ｍｍ角の試験片を採取し、適切に研磨・腐食することで最終パス原質部のミクロ組織を観察して、１００倍の視野でδフェライトの面積率を測定した。面積率の測定には点算法を用い、１視野につき６００点以上の格子点から面積率を算出した。
　なお、δフェライトは溶接中にオーステナイトに変態せず残留したものであり、強度やじん性に悪影響を及ぼし、溶接継手性能が劣化するため、面積率が小さいほうが良好である。したがって、評価基準としては、δフェライトの面積率が５％未満であったものを評価「Ａ」（優良）とし、５％以上、１０％未満であったものを評価「Ｂ」（良好）とし、１０％以上であったものを評価「Ｃ」（不良）とした。 (Measurement of δ-ferrite area ratio)
A 12 mm square test piece including the final pass original part of the cross section perpendicular to the welding direction was taken from the obtained weld metal before PWHT, and the microstructure of the final pass original part was observed by appropriately polishing and corroding it, and the area ratio of δ-ferrite was measured in a field of view of 100 times. The point counting method was used to measure the area ratio, and the area ratio was calculated from 600 or more lattice points per field of view.
In addition, δ-ferrite is a material that does not transform into austenite during welding and remains, and since it adversely affects strength and toughness and deteriorates the performance of the welded joint, the smaller the area ratio, the better. Therefore, as the evaluation criteria, an area ratio of δ-ferrite of less than 5% was rated as "A" (excellent), an area ratio of 5% or more but less than 10% was rated as "B" (good), and an area ratio of 10% or more was rated as "C" (bad).
（引張試験）
　得られた溶接金属の板厚中央から、溶接線方向に平行に直径６ｍｍ、標点距離２４ｍｍの引張試験片を採取し、ＪＩＳ　Ｚ　２２４１：２０１１に記載の金属材料引張試験方法に準拠して、溶接金属の室温引張強さ（ＴＳ：Ｔｅｎｓｉｌｅ　Ｓｔｒｅｎｇｔｈ）を測定した。
　なお、評価基準としては、引張試験による測定結果が７２０ＭＰａ以上であったものを評価「Ａ」（優良）とし、６２０ＭＰａ以上７２０ＭＰａ未満であったものを評価「Ｂ」（良好）とし、６２０ＭＰａ未満であったものを評価「Ｃ」（不良）とした。 (Tensile test)
A tensile test piece having a diameter of 6 mm and a gauge length of 24 mm was taken from the center of the plate thickness of the obtained weld metal parallel to the weld line direction, and the room temperature tensile strength (TS: Tensile Strength) of the weld metal was measured in accordance with the tensile test method for metallic materials described in JIS Z 2241:2011.
The evaluation criteria were as follows: a tensile test result of 720 MPa or more was rated as "A" (excellent), a tensile test result of 620 MPa or more but less than 720 MPa was rated as "B" (good), and a tensile test result of less than 620 MPa was rated as "C" (poor).
（シャルピー衝撃試験）
　得られた溶接金属の板厚中央から、溶接線方向に垂直に２ｍｍＶノッチシャルピー衝撃試験片を採取し、ＪＩＳ　Ｚ　２２４２：２００５に記載の金属材料のシャルピー衝撃試験方法に準拠して、２０℃におけるシャルピー衝撃値を測定した。
　なお、シャルピー衝撃値によるじん性の評価基準としては、２０℃におけるシャルピー衝撃試験による吸収エネルギーの測定結果を切り欠き部の原断面積で除したシャルピー衝撃値が６０（Ｊ／ｃｍ２）以上であったものを評価「Ａ」（優良）とし、３４（Ｊ／ｃｍ２）以上６０（Ｊ／ｃｍ２）未満であったものを評価「Ｂ」（良好）とし、３４（Ｊ／ｃｍ２）未満であったものを評価「Ｃ」（不良）とした。
  (Charpy impact test)
A 2 mm V-notch Charpy impact test piece was taken perpendicular to the weld line direction from the center of the plate thickness of the obtained weld metal, and the Charpy impact value at 20° C. was measured in accordance with the Charpy impact test method for metallic materials described in JIS Z 2242:2005.
The evaluation criteria for toughness based on Charpy impact value were as follows: a Charpy impact value of 60 (J/ cm2 ) or more, calculated by dividing the absorbed energy measurement result in a Charpy impact test at 20°C by the original cross-sectional area of the notch, was rated as "A"(excellent); a value of 34 (J/ cm2 ) or more and less than 60 (J/ cm2 ) was rated as "B"(good); and a value less than 34 (J/ cm2 ) was rated as "C" (poor).
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
［評価結果］
　上記表１及び２に示すように、発明例Ｎｏ．Ａ１～Ａ７は、一般的に良好な裏波形成が困難である高Ｃｒ含有量の鋼板同士を溶接した例であるにもかかわらず、使用したソリッドワイヤの化学成分が本発明で規定する数値範囲内であった。したがって、バックシールドガスを使用することなく、優れた外観の裏波を得ることができるとともに、優れた機械的性能を有する溶接金属を得ることができた。８質量％～１０質量％のＣｒ含有量の鋼板の溶接において、裏波ビードの外観不良は鋼板および溶接材料の高Ｃｒ含有量に起因するものであるため、被溶接鋼材のＣｒ含有量が１質量％以上８質量％未満である場合も同様に、本実施形態にかかるソリッドワイヤを適用することができる。すなわち、被溶接鋼材のＣｒ含有量が１質量％以上１０質量％以下である場合に、本発明に係るソリッドワイヤを用いることにより、バックシールドガスを使用することなく良好な溶接金属を得ることができる。 [Evaluation results]
As shown in Tables 1 and 2 above, in the invention examples No. A1 to A7, although steel plates with a high Cr content, which is generally difficult to form a good uranami, were welded together, the chemical composition of the solid wire used was within the numerical range specified in the present invention. Therefore, it was possible to obtain a uranami with excellent appearance and a weld metal with excellent mechanical performance without using back shielding gas. In welding of steel plates with a Cr content of 8% by mass to 10% by mass, the poor appearance of the uranami bead is caused by the high Cr content of the steel plate and the welding material, so the solid wire according to this embodiment can be applied in the same way when the Cr content of the welded steel material is 1% by mass or more and less than 8% by mass. In other words, when the Cr content of the welded steel material is 1% by mass or more and 10% by mass or less, by using the solid wire according to the present invention, a good weld metal can be obtained without using a back shielding gas.
　一方、比較例Ｎｏ．Ｂ１～Ｂ７は、ソリッドワイヤ中のＳｉ含有量が本発明で規定する下限値未満であり、さらに比較例Ｎｏ．Ｂ５～Ｂ７は、ソリッドワイヤ中のＴｉ含有量が本発明で規定する上限値を超えていた。したがって、裏波の評価結果が不良となった。また、比較例Ｎｏ．Ｂ８はソリッドワイヤ中のＳｉ含有量が本発明で規定する上限値を超えていたため、δフェライトの面積率が増加した。さらに比較例Ｎｏ．Ｂ９及びＢ１０は、ソリッドワイヤ中のＳｉ含有量が本発明で規定する上限値を超えていたため、δフェライトの面積率が増加するとともに、じん性の評価結果が不良となった。 On the other hand, in Comparative Examples B1 to B7, the Si content in the solid wire was less than the lower limit specified in the present invention, and in Comparative Examples B5 to B7, the Ti content in the solid wire exceeded the upper limit specified in the present invention. Therefore, the evaluation result of the back wave was poor. In Comparative Example B8, the Si content in the solid wire exceeded the upper limit specified in the present invention, so the area ratio of δ ferrite increased. In Comparative Examples B9 and B10, the Si content in the solid wire exceeded the upper limit specified in the present invention, so the area ratio of δ ferrite increased and the evaluation result of the toughness was poor.
　以上、各種の実施の形態について説明したが、本発明はかかる例に限定されないことは言うまでもない。当業者であれば、特許請求の範囲に記載された範疇内において、各種の変更例又は修正例に想到し得ることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。また、発明の趣旨を逸脱しない範囲において、上記実施の形態における各構成要素を任意に組み合わせてもよい。 Although various embodiments have been described above, it goes without saying that the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components in the above embodiments may be combined in any manner as long as it does not deviate from the spirit of the invention.
　なお、本出願は、２０２２年１１月２日出願の日本特許出願（特願２０２２－１７６３８６）に基づくものであり、その内容は本出願の中に参照として援用される。 This application is based on a Japanese patent application (Patent Application No. 2022-176386) filed on November 2, 2022, the contents of which are incorporated by reference into this application.

Claims (5)

  1. 　１質量％以上１０質量％以下のＣｒを含有する鋼材の溶接に用いられるソリッドワイヤであって、
    　ワイヤ全質量に対して、
    　Ｃ：０．０５質量％以上０．１５質量％以下、
    　Ｓｉ：０．８質量％以上１．７質量％以下、
    　Ｍｎ：０．４質量％以上１．２質量％以下、
    　Ｃｒ：７．５質量％以上１３．０質量％以下、
    　Ｍｏ：０．７０質量％以上１．５質量％以下、
    　Ｎｂ：０．０１０質量％以上０．１０質量％以下、
    　Ｖ：０．１０質量％以上０．５０質量％以下、
    　Ｎ：０．０１０質量％以上０．０７０質量％以下を含有し、
    　Ｐ：０．０３０質量％以下、
    　Ｓ：０．０３０質量％以下、
    　Ｎｉ：０．８０質量％以下、
    　Ｔｉ：０．０２５質量％以下、
    　Ａｌ：０．０２０質量％以下、
    　Ｃｏ：０．７０質量％以下、であり、
    　残部がＦｅ及び不可避的不純物からなることを特徴とするソリッドワイヤ。     A solid wire used for welding a steel material containing 1 mass% or more and 10 mass% or less of Cr,
    For the total mass of wire,
    C: 0.05% by mass or more and 0.15% by mass or less,
    Si: 0.8% by mass or more and 1.7% by mass or less,
    Mn: 0.4% by mass or more and 1.2% by mass or less,
    Cr: 7.5% by mass or more and 13.0% by mass or less,
    Mo: 0.70% by mass or more and 1.5% by mass or less,
    Nb: 0.010% by mass or more and 0.10% by mass or less,
    V: 0.10% by mass or more and 0.50% by mass or less,
    N: 0.010% by mass or more and 0.070% by mass or less;
    P: 0.030% by mass or less,
    S: 0.030% by mass or less,
    Ni: 0.80 mass% or less,
    Ti: 0.025% by mass or less,
    Al: 0.020% by mass or less,
    Co: 0.70% by mass or less;
    The balance of the solid wire is Fe and unavoidable impurities.
  2. 　さらに、ワイヤ全質量に対して、
    　Ｚｒ：０．１０質量％以下、
    を含有することを特徴とする、請求項１に記載のソリッドワイヤ。     Furthermore, for the total mass of the wire,
    Zr: 0.10 mass% or less,
    2. The solid wire according to claim 1, comprising:
  3. 　さらに、ワイヤ全質量に対して、
    　Ｃｕ：０．５０質量％以下、
    を含有することを特徴とする、請求項１又は２に記載のソリッドワイヤ。     Furthermore, for the total mass of the wire,
    Cu: 0.50% by mass or less,
    3. The solid wire according to claim 1, further comprising:
  4. 　１質量％以上１０質量％以下のＣｒを含有する鋼材に対して、請求項１又は２に記載のソリッドワイヤを用いて、バックシールドガスを使用せずに溶接することを特徴とするガスシールドアーク溶接方法。 A gas-shielded arc welding method for welding steel containing 1% to 10% by mass of Cr using the solid wire described in claim 1 or 2 without using back shielding gas.
  5. 　１質量％以上１０質量％以下のＣｒを含有する鋼材に対して、請求項３に記載のソリッドワイヤを用いて、バックシールドガスを使用せずに溶接することを特徴とするガスシールドアーク溶接方法。 A gas-shielded arc welding method for welding steel containing 1% by mass or more and 10% by mass or less of Cr using the solid wire described in claim 3 without using back shielding gas.
PCT/JP2023/036286 2022-11-02 2023-10-04 Solid wire and gas-shielded arc welding method WO2024095678A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0796390A (en) * 1993-09-29 1995-04-11 Kobe Steel Ltd Wire for welding 9cr-1mo steel
WO2012014932A1 (en) * 2010-07-30 2012-02-02 新興プランテック株式会社 Method for welding austenitic stainless steel
JP2016022504A (en) * 2014-07-18 2016-02-08 株式会社神戸製鋼所 TANDEM SUB-MERGE ARC WELDING METHOD FOR HIGH Cr GROUP CSFE STEEL
JP2022135634A (en) * 2021-03-05 2022-09-15 株式会社神戸製鋼所 One-side welding method and flux-cored wire

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0796390A (en) * 1993-09-29 1995-04-11 Kobe Steel Ltd Wire for welding 9cr-1mo steel
WO2012014932A1 (en) * 2010-07-30 2012-02-02 新興プランテック株式会社 Method for welding austenitic stainless steel
JP2016022504A (en) * 2014-07-18 2016-02-08 株式会社神戸製鋼所 TANDEM SUB-MERGE ARC WELDING METHOD FOR HIGH Cr GROUP CSFE STEEL
JP2022135634A (en) * 2021-03-05 2022-09-15 株式会社神戸製鋼所 One-side welding method and flux-cored wire

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