Classifications

• • 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°C
  • B23K35/3053—Fe as the principal constituent
  • B23K35/3073—Fe as the principal constituent with Mn as next major constituent
• • 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
  • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
  • B23K35/0255—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in welding
  • B23K35/0261—Rods, electrodes or wires
• • 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
  • B23K35/36—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
  • B23K35/3601—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
  • B23K35/3602—Carbonates, basic oxides or hydroxides
• • 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
  • B23K35/36—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
  • B23K35/362—Selection of compositions of fluxes
• • 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
  • B23K9/18—Submerged-arc welding
• • 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
  • B23K9/18—Submerged-arc welding
  • B23K9/186—Submerged-arc welding making use of a consumable electrodes
• • 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
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • 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
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • 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
  • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
• • 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
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • 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
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • 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
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
• • 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
  • B23K35/40—Making wire or rods for soldering or welding
  • B23K35/406—Filled tubular wire or rods
  • B23K2035/408—Filled tubular wire or rods with welded longitudinal seam
• • 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
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/02—Iron or ferrous alloys
  • B23K2103/04—Steel or steel alloys
• • 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
  • B23K35/36—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
  • B23K35/3601—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
• • 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
  • B23K35/36—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
  • B23K35/3601—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
  • B23K35/3607—Silica or silicates
• • 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
  • B23K35/36—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
  • B23K35/3601—Selection of non-metallic compositions, e.g. coatings or fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
  • B23K35/361—Alumina or aluminates

Definitions

• the present invention relates to a metal cored wire for submerged arc welding, and more particularly to a metal cored wire suitable for submerged arc welding of high Mn content steel used in an extremely low temperature environment and a submerged arc welding method using the same.
• Liquefied natural gas (hereinafter also referred to as "LNG”) is said to be a clean fuel that does not generate air pollutants such as sulfides and oxides because it does not contain sulfur, and its demand is increasing.
• containers (tanks) for transporting or storing LNG are required to retain excellent cryogenic impact toughness at temperatures below -162°C, which is the liquefaction temperature of LNG. . Therefore, aluminum alloys, 9% Ni steels, austenitic stainless steels, etc. have conventionally been used as materials for containers and the like due to the need to maintain excellent cryogenic impact toughness.
• high Mn-containing steel materials containing Mn in the range of 10 to 35% by mass have been used as materials for containers for transporting or storing LNG.
• High-Mn steel has an austenitic phase metal structure even at extremely low temperatures, does not cause brittle fracture, and has a higher strength than austenitic stainless steel. Therefore, there has been a demand for the development of a welding material capable of stably welding such high-Mn steel.
• Patent Document 1 In response to such a demand, for example, in Patent Document 1, C: 0.15 to 0.8%, Si: 0.2 to 1.2%, Mn: 15 to 34%, Cr : 6% or less, Mo: 1.5 to 4%, S: 0.02% or less, P: 0.02% or less, B: 0.01% or less, Ti: 0.09 to 0.5%, N : 0.001-0.3%, TiO 2 : 4-15%, one or more selected from SiO 2 , ZrO 2 and Al 2 O 3 Total: 0.01-9%, K, Na and one or more selected from Li: 0.5 to 1.7%, one or more of F and Ca: 0.2 to 1.5%, the balance containing Fe and other inevitable impurities
• a flux-cored arc welding wire having a composition is disclosed.
• Welding using the flux-cored arc welding wire disclosed herein provides excellent low-temperature toughness with a Charpy impact test absorption energy of 28 J or more at a test temperature of -196 ° C. and high strength with a room temperature tensile strength of 400 MPa or more.
• the wire composition is adjusted to Mo: 1.5% or more, and it is possible to secure a welded joint having excellent hot crack resistance.
• Patent Document 2 in mass%, C: 0.2 to 0.8%, Si: 0.15 to 0.90%, Mn: 17.0 to 28.0%, P: 0.03 % or less, S: 0.03% or less, Ni: 0.01 to 10.00%, Cr: 0.4 to 4.0%, Mo: 0.01 to 3.50%, B: 0.0010% less than N: 0.12% or less, the balance has a basic composition consisting of Fe and unavoidable impurities, and if necessary, one or more selected from V, Ti and Nb, and further , Cu, Al, Ca and REM.
• the amount of fume generation is small, and the yield strength at room temperature (0.2% yield strength) is high strength of 400 MPa or more, and the test temperature: - It is said that it is possible to produce welded joints with high strength and excellent cryogenic impact toughness such that the absorbed energy (vE ⁇ 196 ) in a Charpy impact test at 196° C. is 28 J or more.
• Patent Document 1 has a problem that a large amount of fume is generated during welding.
• the present invention solves the above-described problems of the prior art, generates less fume at the time of welding, and is suitable as a welding material for high Mn content steel materials used in cryogenic environments, high strength and excellent cryogenic temperatures.
• An object of the present invention is to provide a wire for submerged arc welding capable of forming a weld metal having both toughness and toughness.
• the phrase “the amount of fumes generated during welding is small” refers to the case where the amount of fumes generated during welding is 400 mg/min or less in accordance with JIS Z 3930-2013.
• “high strength” refers to the case where the room temperature yield strength (0.2% yield strength) of the weld metal manufactured in accordance with the provisions of JIS Z 3111 is 400 MPa or more
• “excellent cryogenic “Toughness” refers to the case where the absorbed energy (vE ⁇ 196 ) of a weld metal manufactured in accordance with JIS Z 3111 in a Charpy impact test at a test temperature of ⁇ 196° C. is 28 J or more.
• SAW submerged arc welding
• the inventors of the present invention have found that, in response to such problems, the stipulated 0.2% proof stress can be satisfied even if the crystal grains are coarsened by containing 3.5% or more of Mo in the welding material. . Furthermore, when the Mo content is 3.5% or more, the wire drawability of solid wires is remarkably lowered, making it difficult to manufacture.
• the present invention was completed based on these findings and further studies, and the gist of the present invention is as follows. [1] % by mass, C: 0.20 to 0.80%, Si: 0.15 to 0.90%, Mn: 17.0-28.0%, P: 0.030% or less, S: 0.030% or less, Ni: 0.01 to 10.00%, Cr: 0.4 to 4.0%, Mo: 3.50-10.00%, B: 0.0010% or less, A metal cored wire for submerged arc welding having a composition containing N: 0.200% or less and the balance being Fe and unavoidable impurities.
• the steel material to be welded is mass %, C: 0.20 to 0.80%, Si: 0.15 to 0.90%, Mn: 15.0-30.0%, P: 0.030% or less, S: 0.030% or less, Ni: 3.00% or less, Cr: 1.0 to 8.0%, with the balance being Fe and unavoidable impurities,
• the steel material in addition to the composition, further contains, in mass%, V: 2.0% or less, Ti: 1.0% or less, Nb: 1.0% or less, Al: 0.100% or less, N: 0.120% or less, O: 0.0050% or less, A submerged arc welding method containing one or more selected from B: 0.0020% or less and REM: 0.020% or less.
• V 2.0% or less
• Ti 1.0% or less
• Nb 1.0% or less
• Al 0.100% or less
• N 0.120% or less
• O 0.0050% or less
• a submerged arc welding method containing one or more selected from B: 0.0020% or less and REM: 0.020% or less.
• the present invention is a welding material for high Mn content steel, which is excellent in wire manufacturability, can be applied to submerged arc welding with little fume generation, and has high strength and cryogenic toughness even when used for welding with a large heat input. It is possible to provide a metal cored wire for submerged arc welding from which a weld metal having excellent ductility can be obtained, which has a remarkable industrial effect.
• the present invention is a submerged arc welding method for high Mn content steel.
• SAW submerged arc welding
• SAW is a welding method in which an electrode wire is continuously supplied in powdery flux that has been pre-dispersed on the base material, and an arc is generated between the tip of the electrode wire and the base material for continuous welding. is.
• This SAW has the advantage of being able to weld efficiently by applying a high current to increase the deposition rate of the wire.
• the wire As the wire, a solid wire or a flux-cored wire containing wire flux inside the wire is used, but in the present invention, a metal-cored wire is used.
• steel materials are butted together to form a 45° V groove, and a prepared wire (diameter 3.2 mm ⁇ ) is used to spray flux, then no preheating, downward posture current: 350-650A (AC), voltage: 28-36V, welding speed: 20-80cm/min, welding heat input: 0.7-8.0kJ/mm, interpass temperature: 100-150°C condition.
• the high Mn steel as the base material is butted together, and the metal cored wire and welding flux according to the present invention, which will be described later, are used to produce the weld metal that forms the welded joint.
• C is an element that has the effect of increasing the strength of the weld metal by solid-solution strengthening, and C stabilizes the austenite phase and improves the cryogenic impact toughness of the weld metal.
• the content of 0.20% or more is required. Therefore, the C content is made 0.20% or more.
• the C content is preferably 0.30% or more.
• the C content is more preferably 0.40% or more.
• the C content is more preferably 0.45% or more.
• the C content should be 0.80% or less.
• the C content is preferably 0.70% or less.
• the C content is more preferably 0.60% or less.
• the C content is more preferably 0.55% or less.
• Si acts as a deoxidizing agent, increases the yield of Mn, increases the viscosity of the molten metal, stably maintains the bead shape, and has the effect of reducing the occurrence of spatter.
• the content of 0.15% or more is required. Therefore, the Si content is set to 0.15% or more.
• the Si content is preferably 0.20% or more.
• the Si content is more preferably 0.30% or more.
• the Si content is more preferably above 0.30%. However, if the content exceeds 0.90%, the cryogenic toughness of the weld metal is lowered.
• the Si content should be 0.90% or less.
• the Si content is preferably 0.80% or less.
• the Si content is more preferably 0.70% or less.
• the Si content is more preferably 0.60% or less.
• Mn is an element that stabilizes the austenite phase at low cost, and the present invention requires a content of 17.0% or more. If the Mn content is less than 17.0%, a ferrite phase is formed in the weld metal and the toughness at cryogenic temperatures is significantly reduced. Therefore, the Mn content is set to 17.0% or more.
• the Mn content is preferably 18.0% or more.
• Mn content is more preferably 20.0% or more.
• the Mn content is more preferably 21.0% or more.
• Mn is set to 28.0% or less.
• the Mn content is preferably 26.0% or less.
• Mn content is more preferably 24.0% or less.
• P is an element that segregates at grain boundaries and induces hot cracking. In the present invention, it is preferable to reduce P as much as possible, but if it is 0.030% or less, it is permissible. Therefore, the P content is set to 0.030% or less. The P content is more preferably 0.020% or less. In addition, excessive reduction causes a rise in refining cost. Therefore, it is preferable to adjust the P content to 0.003% or more.
• the S content is set to 0.030% or less.
• the S content is preferably 0.020% or less.
• S is preferably adjusted to 0.001% or more.
• Ni is an element that strengthens austenite grain boundaries, segregates at grain boundaries, and improves cryogenic impact toughness. In order to obtain such effects, Ni needs to be contained in an amount of 0.01% or more.
• the Ni content is preferably 1.00% or more.
• the Ni content is more preferably 1.50% or more.
• the Ni content is more preferably 1.80% or more.
• Ni also has the effect of stabilizing the austenite phase, so if the content is further increased, the austenite phase is stabilized and the cryogenic impact toughness of the weld metal is improved.
• Ni is an expensive element, and a content exceeding 10.00% is economically disadvantageous. Therefore, the Ni content should be 10.00% or less.
• the Ni content is preferably 8.00% or less.
• the Ni content is more preferably 4.00% or less. More preferably, the Ni content is 2.50% or less.
• Cr acts as an element that stabilizes the austenite phase at cryogenic temperatures and improves the cryogenic impact toughness of the weld metal. Cr also has the effect of improving the strength of the weld metal. Moreover, Cr raises the liquidus line of the molten metal and acts effectively to suppress the occurrence of hot cracks. Furthermore, Cr also effectively acts to improve the corrosion resistance of the weld metal. In order to obtain such effects, the content of Cr is required to be 0.4% or more. If Cr is less than 0.4%, the above effect cannot be ensured. Therefore, the Cr content is set to 0.4% or more. The Cr content is preferably 0.5% or more. The Cr content is more preferably 0.8% or more. The Cr content is more preferably 1.0% or more.
• Cr is set to 4.0% or less.
• the Cr content is preferably 3.5% or less.
• Cr content is more preferably 3.0% or less.
• the Cr content is more preferably 2.0% or less.
• Mo is an element that strengthens the austenite grain boundaries, segregates at the grain boundaries, and improves the strength of the weld metal. Such an effect becomes remarkable at a content of 3.50% or more. Furthermore, when the Mo content exceeds 3.50%, the 0.2% yield strength is also improved by solid solution strengthening. Therefore, Mo content shall be 3.50% or more. Mo content is preferably 4.00% or more. In addition, if the Mo content exceeds 5.00%, carbides precipitate and further contribute to the improvement of the 0.2% yield strength, so the Mo content is more preferably 5.00% or more. Mo content is most preferably 6.00% or more.
• Mo should be 10.00% or less.
• the Mo content is preferably 9.00% or less.
• Mo content is more preferably 8.00% or less.
• Mo content is more preferably 7.00% or less.
• B segregates at the grain boundaries of the weld metal, thereby strengthening the grain boundaries, and has the effect of improving the toughness and yield strength. Since such an effect becomes remarkable at a B content of 0.0005% or more, the B content is preferably 0.0005% or more. On the other hand, if it is contained excessively, B carbonitrides may be precipitated at the grain boundaries to cause deterioration of toughness. Therefore, the B content should be 0.0010% or less.
• N is an element that is unavoidably mixed, but like C, it is an element that effectively contributes to improving the strength of the weld metal, stabilizes the austenite phase, and stably improves the cryogenic toughness. Since such an effect becomes remarkable at a N content of 0.010% or more, the N content is preferably 0.010% or more. The N content is more preferably 0.050% or more. The N content is more preferably 0.100% or more. However, when the content exceeds 0.200%, nitrides are formed and the low temperature toughness is lowered. Therefore, the N content is set to 0.200% or less. The N content is preferably 0.150% or less.
• the metal cored wire of the present invention has the basic composition described above, and in the present invention, in addition to this basic composition, as an optional composition, V: 0.040% or less, Ti : 0.040% or less and Nb: 0.040% or less, one or more selected from 0.040% or less, and if necessary, Cu: 1.00% or less, Al: 0.100% or less and REM : 0.020% or less.
• V, Ti, and Nb are elements that promote the formation of carbides and contribute to improving the strength of the weld metal, and one or more of them can be selected as necessary.
• V is a carbide-forming element that precipitates fine carbides and contributes to improving the strength of the weld metal. In order to obtain such effects, it is desirable to contain 0.001% or more. Therefore, when V is contained, the V content is preferably 0.001% or more. The V content is more preferably 0.005% or more. However, if the content exceeds 0.040%, the carbides become coarse and the cryogenic toughness is lowered. Therefore, when it is contained, V should be 0.040% or less. The V content is preferably 0.010% or less.
• Ti is also a carbide-forming element, precipitates fine carbides, and contributes to improving the strength of the weld metal.
• Ti precipitates carbides on solidification cell interfaces of the weld metal, and contributes to suppressing the occurrence of hot cracks.
• the Ti content is set to 0.040% or less.
• the Ti content is preferably 0.020% or less.
• the Ti content is more preferably 0.010% or less.
• Nb is also a carbide-forming element, precipitates fine carbides, and contributes to improving the strength of the weld metal.
• Nb precipitates carbides on solidification cell interfaces of the weld metal and contributes to suppression of hot cracking.
• the Nb content is desirably 0.001% or more. Therefore, when Nb is contained, the Nb content is preferably 0.001% or more.
• the Nb content is more preferably 0.005% or more.
• the content of Nb is set to 0.040% or less.
• the Nb content is preferably 0.030% or less.
• Cu is an element that contributes to austenite stabilization
• Al is an element that improves welding workability
• REM is an element that contributes to improvement of workability. It can contain one or more species.
• Cu is an element that stabilizes the austenite phase, and stabilizes the austenite phase even at cryogenic temperatures, thereby improving the cryogenic impact toughness of the weld metal.
• the Cu content is preferably 0.60% or less.
• Cu content is more preferably 0.50% or less.
• Al acts as a deoxidizing agent, increases the viscosity of the molten metal, maintains the bead shape stably, and has important effects of reducing the occurrence of spatter. Also, Al raises the liquidus temperature of the molten metal and contributes to suppressing the occurrence of hot cracks in the weld metal. Since such an effect becomes remarkable at a content of 0.005% or more, it is preferable to contain 0.005% or more of Al. Al content is more preferably 0.010% or more. Al content is more preferably 0.020% or more.
• the Al content is set to 0.100% or less.
• the Al content is preferably 0.060% or less. More preferably, it is 0.050% or less.
• REM refers to rare earth elements such as Sc, Y, La and Ce. It is a strong deoxidizer and exists in the form of REM oxides in the weld metal.
• the REM oxide serves as a nucleation site during solidification, thereby refining crystal grains and contributing to an improvement in the strength of the weld metal. Such an effect becomes remarkable at a content of 0.001% or more. Therefore, if REM is contained, the REM content is preferably 0.001% or more.
• the REM content is more preferably 0.005% or more. However, if the content exceeds 0.020%, arc stability is lowered. Therefore, when it is contained, REM shall be 0.020% or less.
• the REM content is preferably 0.015% or less.
• the remaining composition other than the composition described above consists of Fe and unavoidable impurities.
• unavoidable impurities include O (oxygen), Sn, Sb, As, Pb, and Bi. It is preferable that the amount of O (oxygen) in the wire is 0.15% or less, the amount of Sn, Sb, and As is each 0.005% or less, and the amount of Pb and Bi is each 0.0001% or less. .
• the inclusion of unavoidable impurity elements other than these is not prohibited, and such embodiments are also included in the technical scope of the present invention.
• any method of manufacturing a commonly used metal cored wire can be applied to the manufacturing of the metal cored wire of the present invention.
• a thin steel plate plate thickness 0.5 mm
• a composition of 0.1% C-0.2% Si-0.5% Mn-balance Fe is used as a steel outer skin material, and cold bending is performed in the width direction. to form a U shape.
• metal powder (and flux powder) whose components are adjusted so as to have a target wire composition is enclosed in the obtained steel outer sheath, and cold wire drawing is performed to obtain a metal cored wire (diameter: 3.2 to 4.0 mm).
• the above metal powder component composition can be obtained by adjusting metal powder or alloy powder having metal components to be supplemented in order to obtain the total composition of the metal cored wire with respect to the component composition of the steel outer covering material.
• the welding flux either commonly known molten flux or bonded flux can be used.
• chemical components of bond flux include SiO 2 : 10-60%, CaO: 10-60%, MgO: 20-70%, Al 2 O 3 : 10-60%, CaF 2 : 5-30. %, CaCO 3 : 2-20%, etc. can be used.
• the welding flux is not limited to this. In the case of bond flux, it is preferable to dry (200 to 300° C.) before welding.
• a metal cored wire having the composition described above the steel materials described later are butted together, the welding flux described above is sprayed, and then the wire is used to perform welding under the welding conditions described later to produce a weld metal. can be done.
• groove processing is performed so that the steel materials to be welded form a predetermined groove shape.
• the shape of the groove to be formed is not particularly limited, and typical V grooves, double grooves, X grooves, K grooves, etc. for welded steel structures can be exemplified.
• the steel used as the base material is a high Mn-containing steel.
• the steel materials obtained through the conventional steelmaking process and casting process are hot-rolled by adjusting the heating conditions and rolling reduction, and then cooled to produce steel materials (steel sheets). There are other ways to get it.
• the thickness of the steel sheet after rolling is, for example, 6 to 100 mm.
• the high Mn content steel material is a high strength steel material for cryogenic use, and preferably has a Mn content of 15.0 to 30.0%. Specifically, C: 0.20 to 0.80%, Si: 0.15 to 0.90%, Mn: 15.0 to 30.0%, P: 0.030% or less, S: 0.03%. 030% or less, Ni: 3.00% or less, Cr: 1.0 to 8.0%, and the balance is Fe and inevitable impurities. Furthermore, as optional components, V: 2.0% or less, Ti: 1.0% or less, Nb: 1.0% or less, Al: 0.100% or less, N: 0.120 % or less, O (oxygen): 0.0050% or less, B: 0.0020% or less, and REM: 0.020% or less. .
• C is an inexpensive and important element that has the effect of stabilizing the austenite phase.
• the content of C is required to be 0.20% or more. Therefore, the C content is made 0.20% or more.
• the C content is preferably 0.40% or more.
• the Cr content exceeds 0.80%, Cr carbides are excessively formed and the cryogenic impact toughness is lowered. Therefore, the C content should be 0.80% or less.
• the C content is preferably 0.60% or less.
• Si 0.15 to 0.90%
• Si is an element that acts as a deoxidizing agent and contributes to increasing the strength of the steel material by dissolving in steel and solid-solution strengthening. In order to obtain such an effect, the content of 0.15% or more is required. Therefore, the Si content is set to 0.15% or more.
• the Si content is preferably 0.30% or more.
• the Si content should be 0.90% or less.
• the Si content is preferably 0.60% or less.
• Mn is a relatively inexpensive element that has the effect of stabilizing the austenite phase, and is an important element in the present invention for achieving both high strength and excellent cryogenic toughness.
• the content of 15.0% or more is required. Therefore, the Mn content is set to 15.0% or more.
• the Mn content is preferably 20.0% or more.
• the content exceeds 30.0% even if the content exceeds 30.0%, the effect of improving the cryogenic toughness is saturated, and the effect commensurate with the content cannot be expected, which is economically disadvantageous.
• the Mn content is set to 30.0% or less. Mn content is more preferably 26.0% or less.
• P as an impurity, is an element that segregates at grain boundaries and becomes a starting point for stress corrosion cracking. Therefore, the P content should be 0.030% or less.
• the P content is preferably 0.028% or less. More preferably, it is 0.024% or less.
• P is preferably 0.002% or more.
• S 0.030% or less
• S exists as sulfide-based inclusions in steel and lowers the ductility and cryogenic toughness of steel materials and weld metals. Therefore, it is desirable to reduce S as much as possible, but 0.030% or less is permissible. Therefore, the S content should be 0.030% or less.
• the S content is preferably 0.010% or less.
• S is preferably 0.0005% or more.
• Ni is an element that strengthens austenite grain boundaries, segregates at the grain boundaries, and improves cryogenic impact toughness.
• the content is preferably 0.01% or more.
• Ni also has the effect of stabilizing the austenite phase, so if the content is further increased, the austenite phase is stabilized and the cryogenic impact toughness of the weld metal is improved. Therefore, the Ni content is preferably 0.01% or more.
• the Ni content is more preferably 1.00% or more.
• Ni is an expensive element, and a content exceeding 3.00% is economically disadvantageous. Therefore, Ni should be 3.00% or less.
• Cr 1.0 to 8.0%
• Cr is an element that stabilizes the austenite phase and effectively contributes to the improvement of cryogenic toughness and steel strength. Also, it is an effective element for forming a fine crystal region.
• the content of Cr is required to be 1.0% or more. Therefore, the Cr content is set to 1.0% or more.
• the Cr content is preferably 3.5% or more.
• Cr content is preferably 6.5% or less.
• Optional composition of steel The above-described components are the basic composition of the steel material. : 0.100% or less, N: 0.120% or less, O (oxygen): 0.0050% or less, B: 0.0020% or less, and REM: 0.020% or less, or A steel material composition containing two types may also be used.
• V is an element that contributes to the stabilization of the austenite phase and also to the improvement of strength and cryogenic toughness of steel materials. In order to obtain such an effect, when V is contained, it is preferable to contain 0.001% or more of V. The V content is more preferably 0.003% or more. On the other hand, if the V content exceeds 2.0%, coarse carbonitrides increase and become fracture starting points, resulting in a decrease in cryogenic impact toughness. Therefore, when it is contained, V should be 2.0% or less. The V content is preferably 1.7% or less. The V content is more preferably 1.5% or less.
• Ti 1.0% or less
• Ti has the same effect as V, but when it is contained in excess of 1.0%, the carbide coarsens and not only becomes a starting point of fracture, but also coarsening of crystal grains is suppressed, and the cryogenic toughness is improved.
• Ti is contained in an amount of 1.0% or less when it is contained.
• the Ti content is preferably 0.5% or less.
• the Ti content is more preferably 0.3% or less.
• the lower limit is not particularly limited, and may be 0%.
• Nb 1.0% or less
• Nb also has the same effect as V, but when it is contained in an amount exceeding 1.0%, the carbide becomes coarse, and not only does it become the starting point of fracture, but also the coarsening of crystal grains is suppressed, and the cryogenic toughness is reduced. If it is contained, it should be contained at 1.0% or less.
• the Nb content is preferably 0.5% or less.
• the Nb content is more preferably 0.3% or less.
• the lower limit is not particularly limited, and may be 0%.
• Al acts as a deoxidizing agent and is the most commonly used element in the molten steel deoxidizing process for steel materials.
• Al content is more preferably 0.020% or more.
• Al content is more preferably 0.030% or more.
• Al content is made 0.100% or less.
• Al content is more preferably 0.060% or less.
• Al content is more preferably 0.040% or less.
• N is an element that has the effect of stabilizing the austenite phase and effectively contributes to the improvement of cryogenic toughness.
• the N content is preferably 0.005% or more.
• the N content is more preferably 0.006% or more.
• the N content is more preferably 0.020% or more.
• the N content is set to 0.120% or less.
• the N content is preferably 0.040% or less.
• O (oxygen) exists as oxide-based inclusions in steel and reduces the cryogenic toughness of the steel material. Therefore, it is preferable to reduce O (oxygen) as much as possible, but 0.0050% or less is permissible. Therefore, when O (oxygen) is contained, the content of O (oxygen) is set to 0.0050% or less. The O content is preferably 0.0045% or less. On the other hand, in order to extremely reduce O (oxygen) to less than 0.0005%, refining is required for a long time, and the refining cost rises. Therefore, from the viewpoint of economy, when O (oxygen) is contained, the content of O (oxygen) is preferably 0.0005% or more. The O content is more preferably 0.0010% or more.
• B is an element that segregates at grain boundaries and contributes to improving the toughness of steel materials.
• the B content is preferably 0.0001% or more.
• the B content is set to 0.0020% or less.
• the B content is preferably 0.0015% or less.
• the B content is more preferably 0.0010% or less.
• REM 0.020% or less
• REM is an element that has the effect of improving toughness, ductility, and sulfide stress corrosion cracking resistance of steel materials through morphology control of inclusions.
• REM is contained, it is preferably contained in an amount of 0.0010% or more in order to obtain the above effects.
• the REM content is more preferably 0.0015% or more.
• the REM content is more preferably 0.005% or more.
• the content exceeds 0.020%, the amount of nonmetallic inclusions increases, and toughness, ductility, and resistance to sulfide stress cracking decrease. Therefore, when it is contained, REM is made 0.020% or less.
• the balance other than the above components consists of Fe and unavoidable impurities.
• unavoidable impurities include Ca, Mg, Cu, and Mo, and a total content of 0.05% or less is permissible.
• a steel sheath and a metal cored wire with metal powder enclosed in the steel sheath were produced.
• a thin steel plate (thickness 0.5 mm) having a composition of 0.1% C-0.2% Si-0.5% Mn-balance Fe in mass% is used as a steel outer skin material, and cold-rolled in the width direction. It was bent into a U shape. Then, metal powder (and flux powder) whose components are adjusted so as to have the wire composition shown in Table 1 is enclosed in the obtained steel outer sheath, and cold drawing is performed to obtain a metal cored wire for welding. (diameter: 3.2 mm).
• the composition shown in Table 1 is the total value of the steel outer covering and the metal powder.
• a high Mn content steel material for cryogenic use (plate thickness: 20 mm) is butted together to form a 45° V groove, and submerged arc welding is performed using the obtained metal cored wire as a welding material. , the weld metal was obtained in the groove described above.
• the cryogenic high Mn content steel used as the test steel is 0.5% C-0.4% Si-25% Mn-0.02% P-0.01% S-3 in mass%.
• Submerged arc welding was performed using each metal cored wire (diameter 3.2 mm) having the composition shown in Table 1, without preheating, in a downward position, current: 450 to 650 A (AC), voltage: 28 to 36 V, welding speed. : 20 cm/min, interpass temperature: 100 to 150°C.
• the tensile test was performed at room temperature for each of three pieces, and the average value of the obtained values (0.2% yield strength) was taken as the tensile property of the weld metal using the wire.
• the Charpy impact test was performed three times each, the absorbed energy (vE -196 ) at the test temperature of -196°C was determined, and the average value was taken as the cryogenic impact toughness of the weld metal using the wire.
• the V-notch position of the Charpy impact test piece was set at the center of the weld metal with a plate thickness of 1/2t.
• Joint No. 1 to No. 10, No. 19 to No. All of the 21 examples of the present invention have a yield strength (0.2% yield strength) at room temperature of 400 MPa or more even in welding with a large heat input, and the test temperature: -196 ° C.
• the absorbed energy (vE -196 ) was a welding material capable of obtaining a weld metal having both high strength and excellent cryogenic toughness of 28 J or more.
• weld cracks occurred and the hot cracking resistance decreased, or the 0.2% yield strength at normal temperature was less than 400 MPa, or the absorbed energy ( vE ⁇ 196 ) was less than 28 J, the desired amount of fume generation during welding was small, and a weld metal having both high strength and excellent cryogenic toughness could not be obtained.

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