Flux cored wire for gas-shielded arc welding

Abstract

A flux cored wire, which is obtained by filling the inside of a steel outer skin with a flux, is configured to have a composition that contains, in mass% relative to the total mass of the wire, 0.01-0.12% of C, 0.05% or more but less than 0.30% of Si, 1.0-3.5% of Mn, 0.1% or more but less than 1.0% of Ni, 0.10-0.30% of Mo, 0.1-0.9% of Cr, 4.5-8.5% of TiO2, 0.10-0.40% of SiO2, 0.03-0.23% of Al2O3 and 80% or more of Fe.

Description

technical field [0001] The invention relates to a gas-shielded arc welding flux-cored welding wire. More specifically, it relates to a gas-shielded arc welding flux-cored wire used for welding steel materials having a tensile strength of 490 to 670 MPa. Background technique [0002] Conventionally, various studies have been conducted for the purpose of improving welding workability and improving the mechanical properties of the weld metal in flux-cored welding wires used for gas-shielded arc welding of steel materials with a tensile strength of 490 to 670 MPa. (For example, refer to Patent Documents 1 and 2.). [0003] Patent Document 1 proposes a flux-cored wire for gas-shielded arc welding, which has good welding operability in all postures, and obtains a weld metal excellent in strength and low-temperature toughness in the as-welded state (AW) and after heat treatment (PWHT). , and the wire composition is limited. The flux-cored welding wire described in Patent Documen...

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Problems solved by technology

[0010] However, in the flux-cored welding wire of the above-mentioned Patent Document 1, in order to ensure excellent low-temperature toughness, 0.1 to 3.0 mass % of Ni is added, and the Ni content of the weld metal may exceed 1 mass %, which cannot sufficiently cope with NACE. Require

In addition, the flux-cored welding wire described in Patent Document 1 lacks research on heat treatment conditions, and it is not clear whether a weld metal that is still excellent in yield strength, strength, and low-temperature toughness can be obtained when heat treatment is performed under more severe conditions.

[0011] In addition, the flux-cored wire described in Citation 2 also contains Ni at 1.0 to 3.0% by mass, so it cannot meet the requirements of NACE.

In addition, in this flux-cored welding wire, the performance of the weld metal after heat treatment has not been studied, and similar to the flux-cored welding wire described in Citation 1 above, if heat treatment is performed under stricter conditions, whether the strength and Weld metals that are still excellent in low temperature toughness are not clear

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