Flux for use in submerged arc welding

Abstract

Provided is a flux for use in submerged arc welding, capable of reducing the moisture content in the flux and the amount of diffusible hydrogen in the welding metal, and exhibiting favorable welding activity, regardless of whether the welding power source is of the alternating current or the direct current type. The composition of this flux for use in submerged arc welding contains MgO in the amount of 25-35 mass%, F in the amount of 15-35 mass% when calculated as CaF2, Al2O3 in the amount of 10-25 mass%, SiO2 in the amount of 10-20 mass%, one or more of Na when calculated as Na2O, K when calculated as K2O, and Li when calculated as Li2O in the total combined amount of 0.5-6.5 mass%, Fe in the amount of 0.5-5 mass% when calculated as FeO, TiO2 in the amount of 1-5 mass%, CaO in the amount of 6 mass% or less (including 0 mass%), Mn in the amount of less than 2.0 mass% when calculated as MnO (including 0 mass%), water-soluble SiO2 in the amount of 1.0 mass% or less (including 0 mass%), water-soluble Na2O in the amount of 1.0 mass% or less (including 0 mass%), and water-soluble K2O in the amount of 0.8 mass% or less (including 0 mass%). In addition, the C content thereof is 0.2 mass% or less (including 0 mass%). Furthermore, the flux composition satisfies mathematical formula (I), given that the MgO content is [MgO], the Al2O3 content is [Al2O3], the F content when calculated as CaF2 is [CaF2], and the TiO2 content is [TiO2].

Description

technical field [0001] The present invention relates to a flux for submerged arc welding. Background technique [0002] Flux used for submerged arc welding can be broadly classified into melting type flux and firing type according to its form. Melting flux is produced by melting various raw materials in an electric furnace and crushing them. On the other hand, firing-type flux is produced by combining various raw materials with a binder such as alkali silicate, granulating them, and firing them. [0003] In addition, sintered flux is classified according to the firing temperature. Generally, those fired at 400°C or higher and lower than 600°C are called low-temperature sintered fluxes, and those fired at 600-1200°C are called high-temperature sintered fluxes. Furthermore, in low-temperature firing-type fluxes, various studies have been made in order to reduce the diffusion of hydrogen into the weld metal (see Patent Documents 1 to 3). For example, Patent Documents 1 to 3 ...

AI Technical Summary

Problems solved by technology

In addition, in the technology described in Patent Document 4, the specific surface area is attempted to be reduced, but the specific surface area of ​​the flux has a significant influence on the protective properties of the slag during welding.

Specifically, if the specific surface area of ​​the flux is reduced, the protective properties of the slag will be impaired, the nitrogen content in the weld metal will increase, and the toughness of the weld metal will deteriorate.

[0014] On the other hand, the technology described in Patent Document 5 regarding high-temperature sintered flux, in which the flux components are designed for the main purpose of dealing with AC welding power sources, is most likely to occur when using DC welding power sources. Sexual deterioration not considered

That is, with the flux described in Patent Document 5, if the welding power source is a direct-current type, the same effect as when an alternating-current type is used cannot be obtained.

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