Flux-cored wire for gas shielded arc welding

Abstract

A flux-cored wire for gas shielded arc welding according to the present invention is formed by filling a steel casing with flux, wherein: the flux contains, by mass percentage to the total mass of the wire, titanium dioxide: 4.0 to 8.0%, alkali metal fluoride (fluorine equivalence): 0.02 to 0.40%, and PTFE (fluorine equivalence): 0.02 to 0.40%; the fluorine equivalence of alkali-earth metal fluoride is regulated to 0.01% or less by mass; and the fluorine equivalence of alkali metal fluoride and the fluorine equivalence of PTFE satisfy the following expressions; (fluorine equivalence of alkali metal fluoride) / (fluorine equivalence of polytetrafluoroethylene) 1, and (fluorine equivalence of alkali metal fluoride + 0.35) / (fluorine equivalence of polytetrafluoroethylene) >=1. By the configuration, diffusible hydrogen is prevented from intruding into a weld during arc welding and the wire is excellent in resistance to hygroscopicity and further shows good welding operability.

Description

technical field [0001] The present invention relates to a powder-cored welding wire for gas-shielded arc welding, which makes it possible to delay cracking until after welding is almost non-existent by: making flux particles hardly adhering to water molecules and thus hardly absorbing moisture; reducing intrusion into the weld metal hydrogen in ; and thereby reducing diffusible hydrogen. Background technique [0002] So far, there has been a problem that hydrogen atoms are trapped in the weld metal due to moisture absorption by the welding material and this leads to hydrogen embrittlement of the weld. In order to deal with this problem, attempts have been made to reduce adhering water by calcining welding materials at high temperatures, and welding wires of seamless structure have been put into practical use as cored welding wires for the purpose of making welding materials hardly absorb moisture. However, there is a problem in that the production cost of the seamless struc...

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Problems solved by technology

[0002] So far, the problem has been that hydrogen atoms are trapped in the weld metal due to moisture absorption by the welding material and this leads to hydrogen embrittlement of the weld

[0006] However, in the case of the technology described in JP-B No. 110432 / 1995, although PTFE powder is mixed in the flux for the purpose of reducing diffusible hydrogen, the problem with this technology is that the moisture absorption resistance is not improved, and welding is operable Performance deteriorates due to mixing with PTFE powder

[0007] Furthermore, in the case of the conventional technique described in JP-A No. 224883 / 2002, although the moisture absorption resistance of welding wire is improved by mixing resin powder with flux, the problem of reducing diffusible hydrogen is not considered at all

In addition, although the amount of spatter generated is suppressed to the limit by reducing the amount of mixed resin powder required to improve moisture absorption resistance as much as possible, there is a problem in that it is difficult to achieve both improvement of moisture absorption resistance and suppression of moisture absorption. The amount of spatter generated, therefore, poor welding operability such as arc stability

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